TRICUSPID VALVE DISEASE

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TRICUSPID VALVE DISEASE Clinical Evaluation, Physiopathology, and Management Alvin S. Blaustein, MD, and Anand Ramanathan, MD

This article discusses the recognition and management of major disorders of the tricuspid valve in the context of altered anatomy and physiology. Firkt, selected congenital lesions in which the tricuspid valve is an important, often primary component of the complex are discussed, then acquired causes of valvar insufficiency and finally restricted inflow are discussed. Ultrasound imaging and Doppler flow interrogation allow bedside analysis of the pathoanatomy and altered physiology, correlate beautifully with careful physical examination, and provide insight into cause and severity that are important factors in clinical decision making. FUNCTIONAL ANATOMY The tricuspid valve is part of the right ventricular inflow tract: great systemic veins, right atrium, and tricuspid valve with supporting apparatus. Its components include a fibrous annular ring, leaflet tissue, chordae tendineae, and papillary muscles (Fig. 1).The tricuspid orifice is larger (11.0 cm circumference on average) than the mitral and is occluded by three triangular or trapezoidal leaflets arising from a continuous membranous curtain inserted into the annulus. The

anterior leaflet extends anteriorly from the infundibulum beneath the pulmonary valve to the inferolateral wall. The septal leaflet attaches to both membranous and muscular portions of the septum and is displaced toward the apex relative to the anterior mitral leaflet. The posterior cusp runs from the septum to inferolateral wall. Each cusp has a strong central fibrous portion and filamentous, translucent perimeter into which chordae are inserted. Adjacent margins of leaflets are connected by chordae tendineae, which also attach to the strong central portion of the leaflets. They then join, extending to papillary muscles or ventricular wall. Lying beneath the commissures, the posterior and septal muscles emanate directly from the ventricular myocardium, whereas the anterior papillary muscle arises from the moderator band as well as the wall. Unique features of the tricuspid valve apparatus (three leaflets, dual origin of anterior papillary muscle, and apical displacement of the septal leaflet) identify the morphologic right-sided structures in some forms of congenital heart disease.l", Iho, lh4 The tricuspid valve serves to guard and regulate flow into the right ventricle and to direct flow toward the outflow segment during systole. Functionally, it parallels the mitral valve, depending on atrial and ventricular

From the Cardiac Non-Invasive Laboratory, VA Medical Center (ASB), Department of Medicine (ASB), and Division of Cardiovascular Medicine (AR), Baylor College of Medicine, Houston, Texas

CARDIOLOGY CLINICS VOLUME 16 * NUMBER 3 * AUGUST 1998

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Figure 1. Cross-section of the adult heart at the base illustrating the tricuspid leaflets and their relation to adjoining structures.

myocardium, papillary muscles, annulus, leaflets, and chordae to coordinate and sustain function. Disorders that restrict inflow or permit regurgitation affect right ventricular output and cause important secondary changes in the right atrium and systemic venous circulation. Conditions that enlarge the right-sided chambers as well as those that alter structure or geometry of the other elements effect important alterations in valvular function. An almost invariable consequence of tricuspid valve disease is elevated right atrial pressure. In addition to promoting systemic venous congestion, elevations in right atrial pressures may facilitate right-to-left shunting when the anatomic correlates are present. Despite sometimes dramatic clinical findings, however, it is not usually the functional or anatomic tricuspid abnormalities that determine prognosis. In congenital lesions, the accompanying malformations have an important impact on clinical presentation, course, and therapy; in acquired diseases, outcomes are linked primarily to the underlying cardiac, pulmonary, or systemic disease. CONGENITAL ABNORMALITIES

Congenital abnormalities are as follows: Tricuspid atresia Tricuspid stenosis Ebstein’s anomalv Congenital tricuspid regurgitation Atrioventricular septal defect

Developmental Considerations

The tricuspid valve forms in two phases.71 In the first, occurring as early as 6 weeks of gestation, a myocardial gully guides atrial blood toward the middle of the ventricle. Initially the gully has a single orifice pointed toward the outflow section of the chamber, but at 7 weeks, a second orifice develops forming the inflow segment. The septal and inferior leaflets develop from this gully. Around the same time, the endocardia1 ridges transform into myocardium, the upper part of which forms the interventricular septum. The low portion forms the anterior tricuspid leaflet. It appears that abnormalities in the first phase account for Ebstein’s anomaly and tricuspid atresia, whereas atrioventricular septal defects represent errors of the second phase. In utero, there is functionally a single circulation with parallel pulmonary and systemic circulations. The right ventricle provides 55% of systemic perfusion through a series of shunts. Venous return is exclusively from systemic veins and enters the right ventricle, a comparatively thick-walled chamber, through the tricuspid valve. After birth, the pulmonary circulation opens, shunts close, and the two circulations assume their series configuration. Relief of alveolar hypoxia and accompanying pulmonary vasoconstriction rapidly lowers resistance to right ventricular ejection in the neonate. Thereafter the lungs and vessels grow resulting in a further decrease in pulmonary vascular resistance; the right ven-

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tricle begins a slow involution." Ultimately the impedance of the systemic arterial resistance may be eight times greater than that of the pulmonary circulation. The most common tricuspid abnormalities restrict inflow, resulting in hypoplastic right heart. When the predominant lesion is an intracardiac shunt or right ventricular outflow obstruction, the right ventricle may hypertrophy impressively. This right ventricular predominance is evident in the electrocardiograms of these lesions. In contrast, if loads are applied to the right ventricle after its period of involution, its capacity to hypertrophy is relatively modest, and the electrocardiogram still reflects an important if not preponderant influence of the left ventricle. Tricuspid Atresia and Congenital Stenosis

Tricuspid atresia is the third most common cyanotic congenital 1esi0n.l~~ The systemic venous return crosses the atrial septum (usually through a patent foramen ovale) from a morphologic right atrium to a morphologic left atrium. There, it mixes with pulmonary venous flow, crosses an atrioventricular valve, and enters the only functioning ventricle, which distributes blood to both pulmonary and systemic circulation^."^ This physiology occurs with many anatomic combinations, which share the following features: no physiologic or anatomic connection between morphologic right atrium and ventricle, hypoplasia of the right ventricle, interatrial communication, and often a ventricular septal de132 The left atrium accompanies fect (VSD).113, a morphologic left ventricle. The ventricular origins of the aortic and pulmonary arteries and the degree of obstruction to pulmonary blood flow vary. The anatomic classification into those with and without transposition of the great arteries is summarized in Table 1.

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Classification depends on the positions of the great arteries. In type I, vessels are normally positioned; in types I1 and 111, there is D or L transposition. Microscopic rudiments of the valve and annulus generally exist in all cases.71 All systemic and pulmonary venous blood ultimately returns to the left atrium, although there is inconsequential left-to-right shunting because of instantaneous pressure gradients at the atrial level. Excessive pulmonary flow results when the VSD is not restrictive and pulmonary resistance is low. A restrictive VSD or hypoplastic pulmonary trunk protects the left ventricle, but the patient becomes cyanotic. Most infants with tricuspid atresia present with cyanosis because more than 90% have normally related great arteries and a small VSD, which may close spontaneously. A smaller number usually with transposed great vessels and unrestricted pulmonary flow develop congestive heart failure. Congenital tricuspid stenosis may be a form of atresia in which there is a small tricuspid valve with leaflets and chordae well formed. Clinical Findings

A prominent right atrial jugular venous wave with slow descent characterizes the examination as blood flows from right to left through a relatively restrictive patent foramen. A large u wave also predominates in congenital tricuspid stenosis, but the pressure descends more rapidly than in atresia, and a normal v wave follows. If left ventricular failure develops, mitral regurgitation produces a regurgitant wave transmitted to the right atrium, mimicking tricuspid regurgitation. The absence of a detectable right ventricular impulse in a cyanotic child strongly supports tricuspid atresia. In the most common variant, there is a single (mitral) first heart sound and a loud precordial systolic murmur resulting from flow across the restrictive VSD.

Table 1. CLASSIFICATION OF TRICUSPID ATRESIA

Pulmonary atresia Pulmonary stenosis present Pulmonary stenosis absent

Transposition Present

Transposition Absent

Pulmonary blood flow depends on PDA or arterial collaterals Valvular or subvalvular obstruction influences pulmonary blood flow Pulmonary vascular resistance determines pulmonary flow

Pulmonary blood flow depends on PDA or arterial collaterals Small slitlike VSD limits flow to hypoplastic pulmonary trunk Nonrestrictive VSD. Pulmonary vascular resistance determines pulmonary flow

PDA = Patent ductus arleriosus; VSD

=

ventricular septal defect.

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There may not be any murmur with pulmonary atresia or after spontaneous closure of a VSD. A continuous murmur may accompany arterial collaterals. The examination differs with other unusual anatomic variants. An electrocardiogram showing left ventricular predominance and right atrial enlargement in a cyanotic infant provides valuable confirmation of tricuspid atresia. Left axis deviation indicates the most common anatomic variant with morphologic left ventricle accepting the venous return. A vertical or right axis with adult progression of the QRS is a marker of a large VSD and a morphologic functioning right ventricle.

to-pulmonary artery shunt) secures survival to later ages when more definitive corrective surgery can be performed.13,46, Ebstein’s Anomaly and Congenital Tricuspid Regurgitation

First described in 1864, Ebstein’s anomaly accounts for about 40% of congenital tricuspid valve abnormalities. Three major anatomic features characterize it: 1. Leaflets: Normally attached anterior cusp and apical displacement of the septal and posterior leaflets with shortened chordae that restrict movement occur. Rarely the septal leaflet may be absent. Echocardiography 2. Atrialized right ventricle: The portion of the right ventricle above the displaced Anatomic and Doppler information estableaflets is functionally integrated into the lishes the absence of a tricuspid valve and atrium. This segment is frequently identifies the positions of the great arteries.164 thinned and dilated, in part owing to a With atresia, a thick band of tissue replaces decreased number of myocytes, and has the tricuspid valve; with stenosis, the leaflets a ventricular electrogram. and annulus may be small but well formed 3. Patent foramen ovale: The majority of and arrayed around a tiny annulus. Doppler Ebstein’s anomalies have a patent fora113 The right confirms the absence of men ovale, although some have a secunatrium is enlarged and hypertrophied, and dum defect.*l,ll3, 161 there is flow across a patent foramen ovale or The main determinants of the pathophysiless commonly a secundum atrial septal deology are: fect (ASD). When the defect restricts flow (more common with transposition), the inThe degree of tricuspid incompetence (or, teratrial septum bulges into the left atrium more rarely, stenosis resulting from parand may even obstruct mitral valve inflow.lo8 tially fused or imperforate commissures) This important finding identifies a need for The amount of ventricle incorporated into balloon septostomy. Obstruction to pulmothe right atrium nary flow results not only from the slitlike The extent of shuntingls,19, *l, 113, 16* VSD, but also from infundibular or valvular At birth, the high pulmonary vascular resisstenosis; several sites may coexist. The VSD tance exaggerates the impact of the tricuspid may be in the membranous or muscular sepvalve pathology. Incompetence, the most tum, and its size is proportional to the pulmocommon pathophysiology, worsens because nary artery. The extent of right ventricular the right ventricular systolic pressure is elehypoplasia is closely related to the size of vated. The high atrial pressure increases the the VSD. When the VSD is small, the right right-to-left shunt, but there is seldom a reventricular outflow is absent or underdevelgurgitant atrial wave because the effective oped; it approaches normal when the VSD is atrium is so large. When the valve is stenotic large. The septum and great arteries should or imperforate, cyanosis is more likely. The be examined, the former for hypertrophy, anleft side of the heart is often deformed by eurysm, or adhesion of the mitral apparatus, bulging of the ventricular septum, which disall of which restrict flow, and the great vessels places the mitral apparatus causing prolapse for their origins and sizes and sites of obstrucof the leaflets and impeding filling. On occation. sion, regional dysfunction identifies hearts with increased fibrous content. Management Clinical Findings Although a few cases of survival into adulthood have been reported, initial palliative In severe cases, infants are cyanotic and surgery with a Fontan procedure (right atrialtachypneic. This may resolve as pulmonary

TRICUSPID VALVE DISEASE

vascular resistance falls, leading to an acyanotic period that may extend into adulthood. Older patients appear normal, although they may experience intermittent periods of cyanosis. The jugular pulse is normal except with stenotic lesions that are marked by giant a waves. Later, when right ventricular failure develops, atrial and regurgitant waves may appear. The tricuspid (second) component of the first sound is accentuated because of a conduction delay, hypokinetic right ventricle, and the prolonged excursion of the large anterior leaflet. Tricuspid regurgitation in Ebstein's anomaly produces a grade 2 to 3 systolic murmur just to the left of the sternal border, generally insensitive to respiration because of right ventricular dysfunction. Wide splitting of S2 results from the conduction delay. Patients have exercise intolerance resulting from right ventricular dysfunction and persistent hypoxia, which can improve after surgery in which both valve and atrial septal defect are repaired.82 The electrocardiogram has distinctive features supporting the diagnosis. About a third of patients have a supraventricular tachycardia, at times associated with a preexcitation pattern (type B Wolff-Parkinson-White[WPW]). I' waves are tall and broad, and in the absence of preexcitation, the P-R interval is prolonged and followed by a wide QRS, usually a form of right bundle-branch block. Less often the conduction delay does not fit a specific pattern and may produce a pseudoinfarction pattern in the anterior leads. Echocardiography Ebstein's anomaly can be diagnosed by ultrasound in utero as one cause of tricuspid reg~rgitation.~~ Downward displacement of the septal leaflet, a hallmark finding, is best seen in the apical four-chamber view.'05 The criteria for this displacement in children is 15 mm and in adults 20 mm, or a normalized value of greater than 8 mmM2.'64The severity of the lesion is best quantified by evaluating the relative sizes of the atrialized and functional portions of the right ventricle.18 When the functional right ventricle is less than 35% of the total, patients are likely to require valve replacement. Other views may be best to visualize the leaflet anatomy, position, and geometry. The discovery of extensive leaflet tethering may identify patients who require replacement rather than repair. The short axis demon-

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strates the size of the right ventricle of the dilated outflow tract. Scanning down toward the apex visualizes the paradoxic septal motion associated with right ventricular volume overload. Color and scalar Doppler can provide an accurate classification of the severity of tricuspid regurgitation. The patent foramen ovale is often best visualized in the subcostal long axis, especially in adults, in whom apical views falsely suggest a defect. Management The management of Ebstein's anomaly is evolving. Survival into adulthood is not unusual, with symptoms evolving in the 20s and 3 0 ~ . 585~Symptomatic , (class 3 and 4) patients and those with cardiac enlargement should be considered for surgery, but with earlier diagnosis and improving surgical techniques, more patients may be suitable candidates for anatomic correction (reconstruction with free wall plication and annuloplasty), prosthetic valve (homografts may be preferred), and Fontan procedure in a small minority when a p p r ~ p r i a t e 86 .~~, Congenital Tricuspid Regurgitation

Congenital tricuspid regurgitation results from tricuspid or biventricular atrioventricular valve d y s p l a ~ i a . ~ ~ The , leaflets are thickened, the chordae are shortened, and at times there is focal leaflet malposition. Regurgitation in these cases persists and may be severe. Infants may present with transient severe tricuspid insufficiency, a condition often associated with perinatal stress, and occasionally cyanosis (right-to-left shunting from high right atrial pressures). There may be ischemic ST-T changes on the electrocardiogram and a typical murmur. Limited anatomic data indicate the tricuspid valve is disproportionately enlarged. Almost always, the condition resolves spontaneously after several weeks, suggesting it may be due to a reversible myo58, 144 Eichorn et a132recardial dy~function.~~, ported a small series of adults with severe tricuspid insufficiency thought to have Ebstein's anomaly. All had cleft tricuspid leaflets. Atrioventricular Septa1 Defects

The normal atrioventricular septum separates the right atrium from the left ventricular

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outflow tract. The principal reason for including this complex, also known as endocardial cushion defects, arises from the pathoanatomy of the tricuspid orifice and leaflets, and the confusion of some of the clinical signs with tricuspid pathology or other septal defects. The defects may be principally interatrial or interventricular or, more rarely, a complete common atrioventricular canal. All share these features: Common malformation of a single atrioventricular valve, orifice, and fibrous ring A superiorly displaced left ventricular outflow tract Disproportion between inflow and outflow portions of the chamber Two leaflets are associated with the right ventricle, one with the left, and the anterior and posterior leaflets bridge the septum attached to it by chordae. The common valve can have one common or two separate openings.164 The configuration of the five-leaflet valve varies considerably but can be classified into three fundamental categories:

1. Anterior leaflet committed largely to left ventricle and attached to the crest of the septum. There are two valve openings, and the shunt occurs at atrial level. This is known as ostium primurn defect or partial atrioventricular canal. 2. Chordal attachments extend from anterior leaflet to anomalous papillary muscle in the right ventricle and leaflets are attached to atrial septum. This variant also has a separate orifice for each ventricle, but the shunt is at the ventricular level. The term transitional atrioventricular canal is sometimes applied to this anatomy. 3. Rightward displacement of the anterior leaflet, whichfloats over the crest of the septum. This is present with common atrioventricular canals with a single valve orifice. The two valve openings are generally equal in size, but in some cases the tricuspid orifice overrides a malaligned septum (straddling), which reduces its effective orifice size, and has chordae to both sides of the 162, 164 Rarely the tricuspid or mitral valve may have a double orifice with no VSD.62The configuration of the left atrioventricular valve has an important impact on surgical correction because abnormalities of the anterior

leaflet are associated with more severe mitral reg~rgitation.~~ The major hemodynamic consequences of atrioventricular septal defects depend on the degree of shunting and valvular incompetence. The shunt flow is determined by the size and location of the septal defects, pulmonary vascular resistance, and presence of severe mitral regurgitation that promotes left-to-right shunting. Patients with Down syndrome tend to develop more extensive vascular disease and have underdeveloped pulmonary circulations. Seldom is isolated tricuspid regurgitation clinically important except in common atrioventricular canal or when it develops as a result of infective endocarditis. Clinical Findings A large regurgitant wave in the jugular venous often signifies mitral rather than tricuspid insufficiency. Direct flow across the atrioventricular defect and flow across the ASD from mitral regurgitation converge in the right atrium. In complete atrioventricular canal, the precordium is hyperdynamic because of substantial right ventricular volume overload. The first heart sound is single, a thrill is evident with significant mitral regurgitation, and the murmur radiates to the right of the sternum toward the right atrium, following the path of the septal defect. Middiastolic murmurs arise from flow across the mitral or tricuspid valves or restrictive ASD.lI3 The classic electrocardiogram includes a prolonged PR interval, a markedly leftward axis, and a counterclockwise inscription of the QRS beginning with Q in leads 1 and aVL. The precordial leads display a prominent R wave in leads V, and V3,.Il3 Echocardiography The apical and subcostal windows demonstrate the atrial and ventricular defects well and, with appropriate scanning, their relationship to the anterior and posterior 146 To classify the complex properly, leaflets.100, chordal attachments to the posterior cusps must be identified. The parasternal short axis reveals the cleft mitral leaflet or the common leaflet spanning a subaortic defect. This view also shows abnormal chordal attachments to the septum, but the parasternal vantage is superior for visualizing the defect.'64A gooseneck deformation of the left ventricular out-

TRICUSPID VALVE DISEASE

flow tract results from its anterior displacement and elongation, and a subaortic ring or coarctation is present in about 5% of cases.l13 The transesophageal approach is superior to transthoracic in identifying the dominant ventricle and its diastolic f ~ n c t i 0 n . Finally, l~~ the echo is vital in establishing ventricular dominance because cases best suited for repair have anatomically balanced ventricles.122 ACQUIRED ABNORMALITIES

Acquired abnormalities are as follows: Tricuspid insufficiency Tricuspid stenosis Tricuspid pseudostenosis Tricuspid Insufficiency

Physical examination and echocardiography and Doppler findings are illustrated in Figure 2, and anatomic classification of disorders is illustrated in Figure 3. Physiopathology Tricuspid insufficiency results from alterations in the anatomy of the leaflets and

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chordae or from changes in the geometry of the annulus or function of the muscular elements. Tricuspid insufficiency, defined as retrograde systolic flow from the right ventricle to the right atrium, is principally a volume overload lesion of the right atrium and ventricle and is associated with enlargement of these chambers. When leaflet pathology causes tricuspid insufficiency, the enlargement results from the hemodynamic lesion, whereas insufficiency with normal leaflets is a consequence of right ventricular enlargement or injury resulting from pulmonary hypertension, myopathy, or infarct. Annular enlargement and cusp malalignment f o l l o ~ . ~ ~ ~ The cusps may fail to coapt normally.24,43, 96, lZ3,135 If the lesion is severe (and usually persistent), right ventricular failure eventually develops with chronically elevated venous pressure and engorgement sometimes causing organ dysfunction, edema, and ascites. Tricuspid insufficiency affects the motion of the interatrial and interventricular septae 164 The volume load (ventricular interacti~n).~~? causes the right ventricle to enlarge and assume a more spherical configuration. During diastole, the interventricular septum flattens, and the left ventricle assumes a D shape demonstrated on echocardiography from the

Figure 2. Key clinical features of tricuspid valve stenosis and regurgitation. Included are venous waveforms visible in the jugular veins, the configuration and location of murmurs, and ultrasound findings. Findings in mild and severe regurgitation are differentiated.

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Figure 3. Longitudinal section of the tricuspid valve opened in the middle of the posterior leaflet (represented at both left and right extremes of the figure). Major disorders affecting the components of the tricuspid valve are grouped.

parasternal short-axis window. Septa1 displacement indicates a reversed transseptal pressure gradient (right > left).36,7K The septal shift is most pronounced at the base, reducing the septal-free wall shortening. When the ventricles contract, the pressure in the left ventricle during systole generally exceeds that of the right ventricle, moving the septum toward the right and restoring a more normal left ventricular geometry. This sharp movement of the septum during systole might contribute to right ventricular ejection. When pulmonary hypertension is severe, however, abnormal septal position may be sustained throughout systole. Less apparent and more difficult to demonstrate is a reversal of atrial septal motion in late systole. Observations in patients with significant tricuspid regurgitation demonstrate its effect on left ventricular function. When the tricuspid valve is extirpated for infective endocarditis, left ventricular filling, particularly the atrial contribution, 77, 7K The interatrial septum moves is affected.36, toward and compromises the left atrium, and the displaced interventricular septum compresses the left ventricle. This reduces left ventricular ejection fraction, although this is only partially explained by decreased preload. Clinical Findings Venous Pulsations. Examination of the jugular vein waves in sinus rhythm reveals three positive waves with troughs between.

u wave: represents atrial contraction and is

followed by a plateau c wave: represents ventricular contraction and associated with movement of the tricuspid valve superiorly x descent: atrial pressure initially falls with atrial relaxation and descent of the base D wave: pressure rises as systemic venous return fills the atrium followed by a gradually rising y wave y descent and trough: fall in atrial pressure associated with opening of the tricuspid valve followed by a relaxation trough (z) When tricuspid insufficiency is mild, there are subtle changes in the contour and amplitude of the D component of the jugular veins. Its height first approximates and, as the lesion becomes more severe, exceeds that of the a wave. The troughs are still evident, and mean venous pressures are mildly elevated. As the lesion progresses, a regurgitant component precedes and merges with the D wave forming a ventricularized Y or regurgitant wave, an event that can be palpable as an hepatic pulsation. Severe insufficiency causes the atrial pressure to rise during ventricular systole; the wave actually begins before the physiologic D wave and is not strictly a giant D wave. Atrial fibrillation often accompanies severe tricuspid insufficiency, obfuscating the usual waves and troughs, but the regurgitant wave is easily detected and displays a mark-

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edly different contour than the carotid pulse, which can be simultaneously palpated. In contrast to other lesions that may increase the amplitude of the v wave, the slope of the y descent is rapid with tricuspid insufficiency, and the trough deepens noticeably with inspiration. Precordial Pulsations. Normally, there are no prominent impulses at the third through fifth intercostal spaces near the sternum, although children can have a subtle outward pulsation and adults a mild retraction. With tricuspid insufficiency, a thrill rarely accompanies the murmur, but often a prominent outward thrust is evident. The thrust is forceful but brief with compensated tricuspid regurgitation and more sustained with right ventricular failure or milder degrees of regurgitation accompanying significant pulmonary hypertension. When the right ventricle enlarges and hypertrophies secondary to severe isolated mitral stenosis or other causes of pulmonary hypertension, it displaces the left ventricular apex posteriorly and mimics a prominent left ventricular impulse. Auscultation. Primary tricuspid regurgitation does not predictably alter the first heart sound, but S, is affected by secondary causes (e.g., mitral stenosis or first-degree heart block). A loud S,P frequently signifies existing pulmonary hypertension, and an SB gallop followed by a flow rumble indicates a large inflow volume caused by severe regurgitation. The right ventricular gallop is heard best near the lower sternal edge immediately to the left or right of the sternum. Both the gallop and the rumble intensify with inspiration. Myxomatous valves are identified by late systolic murmurs, whoops, or honks often in conjunction with nonejection clicks, sounds also described in association with pacing electrodes. Milder degrees of insufficiency may not have an audible murmur despite suggestive venous pulsations and evidence of pulmonary hypertension. Murmurs indicating moderate to severe regurgitation are pansystolic and loudest at the left lower sternal border. When the right ventricle has enlarged substantially, the murmur can radiate prominently to the left midclavicular line but not to the axilla, differentiating it from mitral insufficiency. Its intensity increases with inspiration (Carvallo's sign) or firm abdominal pressure. This finding distinguishes it from mitral insufficiency and VSD, other holosystolic murmurs. As mentioned earlier, a diastolic flow rumble indicates either mixed stenosis

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and regurgitation or torrential inflow from severe reg~rgitation.~~ Doppler Echocardiography This technique of measuring and displaying the Doppler shift resulting from moving blood particles now comprises the principle means of diagnosing tricuspid regurgitation. The lesion causes systolic flow disturbance behind the tricuspid valve in the right atrium, which can be displayed as a velocity-time profile (scalar pulsed or continous wave) or as a color-coded map of velocity at each point in the region of interrogation (color flow). The peak velocity of the signal is proportional to the pressure difference between the right ventricle and atrium and provides an estimate of pulmonary artery systolic pressures. Even without Doppler, tricuspid regurgitation can be inferred after a peripheral injection of sono-opaque contrast. After the bubbles enter the right atrium, they can be followed as they move from the right atrium into the inferior vena cava during systole. Generally, contrast material is used now only to enhance weak jets of tricuspid regurgitation, improving estimates of right ventricular systolic pressures.66 Methods used to assess the severity of tricuspid insufficiency are similar from those validated more extensively for mitral and aortic regurgitation. Jet velocity, momentum, proximal jet characteristics, and area are all useful for evaluating severity. Techniques relying on jet area can underestimate the volume flow because the Doppler signal reflects momentum, a function of both mass and velocity. When the pressure difference driving the jet is large (e.g., mitral regurgitation), the area may reflect largely velocity, whereas at the tricuspid valve, the pressure gradient between RV and right atrium may be relatively small, exaggerating the contribution of jet mass (or regurgitant volume) on measured area. Other methods use the continuity equation (which requires a normal reference valve), proximal acceleration, and measurement of the vena c o n t r a ~ t a .124-126, ~ ~ , 155 158 These methods are volumetric and are generally preferred but lack extensive clinical validat i ~ n . ' ~Visual l estimates of the color Doppler signal by experienced readers correlate reasonably well with more quantitative appr~aches.'~~ The flow pattern in the hepatic veins and inferior vena cava provides qualitative infor-

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mation useful for evaluating severity. Normally a forward systolic and diastolic wave, followed by a small atrial reversal, characterizes caval flow toward the right atrium. With moderate or severe tricuspid insufficiency, however, the systolic wave first flattens and even reverses. Doppler techniques can detect tricuspid patients with normal hearts, even before birth. In utero and childhood, the prevalence is 6% to 8%, but with adulthood prevalence increases with age and activity, reaching 90% in several studies.', 40, 72, 115, 156, lb8 Generally the jets identified indicate minimal regurgitation, characterized by a central location with little projection into the right atrium. Tricuspid Stenosis and Pseudostenosis

Physical examination and echocardiography and Doppler findings are illustrated in Figure 2, and anatomic classification is classified in Figure 3. Physiopathology

Pure tricuspid stenosis is a rare lesion occurring primarily as a component of multivalvular rheumatic disease and rarely from carcin ~ i d .92,~I6O~ In , one surgical series examining 363 patients with tricuspid valve disease, only 2% had pure stenosis, and 23% had mixed stenosis and regurgitation: 92% of these patients had postinflammatory disease.48If tricuspid stenosis dominates the clinical picture, pulmonary congestion is absent, and therefore patients do not have orthopnea or paroxysmal nocturnal dyspnea. Even when mitral stenosis is important, the tricuspid disease limits pulmonary flow and reduces the impact of left ventricular inflow obstruction. In cases of pseudostenosis, masses may intermittently or progressively obstruct tricuspid valve inflow and simulate tricuspid stenosis or even precipitate syncope. These are discussed subsequently. Clinical Findings

Venous Pulsations. The principal pulsation is an a wave generally to midneck and occasionally to the jaw. The high atrial pressures during atrial contraction may also be evident as an hepatic pulsation. Although the x descent is steep, the cu waves are normal, and

the y descent is unremarkable. As with other aspects of the examination, the impact of concurrent valvular disease may predominate. Precordial Pulsations. The precordium is generally quiet because the systemic flow into the right ventricle is reduced. Thus, the combination of a giant a wave with a quiet precordium suggests tricuspid stenosis. Leftsided valvular lesions may result in precordial abnormalities because of mitral or aortic lesions. Auscultation. The first heart sound is usually unaltered or accentuated, although its intensity is variable when atrial fibrillation occurs. Respiration does not alter the splitting of the second heart sound because right ventricular inflow is more or less constant. The opening snap is frequently inaudible, and with sinus rhythm the diastolic rumble occurs late in diastole, heard best at the left lower sternal border. The rumble increases with inspiration as transmural right atrial pressure, and therefore the transvalvular gradient increases. A systolic murmur suggests tricuspid regurgitation, which may be the dominant lesion, accentuating the diastolic rumble because of the high flow. Doppler Echocardiography

The stenotic rheumatic tricuspid valve has morphologic features similar to those of the mitral. Most characteristic is doming best visualized from the parasternal right ventricular inflow or apical positions. Motion of the thickened leaflets is restricted. Planimetry, although theoretically possible from the subcostal or transgastric (transesophageal) positions, is not validated. Doppler interrogation illustrates turbulent flow in the ventricle near the annular plane, and continuous-wave envelopes demonstrate the characteristic slow decline of the E wave and a high A velocity in sinus rhythm. Both pressure half-time and continuity equation have provided estimates correlating well with hemodynamic evaluation.* When right atrial pressure is higher than pulmonary artery diastolic pressure, tricuspid inflow may begin before pulmonary outflow has ceased. The echocardiogram is also useful in identifying causes of pseudostenosis, including a variety of primary and secondary cardiac malignancies, native and prosthetic valve endocarditis, and thrombus. *References 1, 35, 40, 69, 72, 111, 115, 120, 156, 168.

TRICUSPID VALVE DISEASE Table 2. CAUSES OF TRlCUSPlD VALVE DYSFUNCTION Tricuspid Insufficiency: Abnormal Leaflets Infective endocarditis Rheumatic heart disease Floppy (myxomatous degeneration) Noninfectious vegetations Trauma Blunt chest trauma Biopsy induced Pacemaker Carcinoid Medication induced Tricuspid Insufficiency: Normal Leaflets Pulmonary hypertension Acute and chronic cor pulmonale Primary pulmonary hypertension Left ventricular failure Mitral and aortic valvular diseases Right ventricular infarction Loeffler’s endocarditis Electrode/catheter induced Tricuspid Stenosis and Pseudostenosis Rheumatic Malignancies Primary Secondary Prosthetic valve stenosis (noninfectious) Infective and noninfective vegetations Thrombi

SPECIFIC CAUSES OF TRICUSPID VALVE DYSFUNCTION

In this section, we review some causes of tricuspid valve dysfunction. The diagnoses are listed in Table 2 and discussed as specific entities subsequently. Anatomic correlates are illustrated in Figure 3. Note that some entities might cause either stenosis or regurgitation. Infective Endocarditis Clinical Features

Endocarditis can result in tricuspid stenosis (large obstructing leaflet vegetations) or regurgitation (vegetations prevent coaptation or cause leaflet destruction) with the latter much more common. In general, tricuspid valve endocarditis accounts for a minority of all cases, occurring at an incidence roughly in proportion to the chamber pressures. The incidence is considerably higher (>50% versus 15%) in patients who inject illicit drugs.16,20, 4y In the drug-free group, most have devices, indwelling catheters, or other infected valves, with primary infection accounting for only about

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1%of all bacterial infective endocarditis.20, Io2, Pulmonary infiltrates, fever, and microscopic hematuria represent a common clinical triad in primary infection.Io3Neurologic complications are relatively uncommon in tricuspid valve endocarditis and are related to the virulence of the organism. Pleural effusions are generally exudative and ~teri1e.I~~ Discrete events suggest embolism and a patent foramen ~ v a l eThe . ~ ~spectrum of causative organisms differs, with Staphylococcus aureus and gram-negative organisms accounting for a high proportion. Fungal infection is also more common, particularly Candida species. Reasons intravenous drug users principally infect the tricuspid valve are speculative and include a large innoculum eluding the reticuloendothelial system, persistent subcutaneous infections, and valve injury from nonpharmacologic vehicles. The examination generally reveals only a hyperdynamic circulation in a febrile patient because murmurs are not universally present, and the degree of insufficiency varies widely. Patients present with an acute febrile illness and a chest radiograph indicative of embolization with focal, widely distributed infiltrates. Io3, 154

Echocardiography

The hallmark of infective endocarditis is the vegetation, which may appear as a sessile or pedunculated mass or strands, attached to either atrial or ventricular valve surfaces, or to its margins. Generally, tricuspid vegetations are larger than mitral or aortic, although this is also influenced by their cause; Staphylococcus and Candida tend to form exuberant vegetations. Vegetation size, however, correlates poorly with outcome.y,4y, 87 When there is a pacemaker electrode or catheter present, the vegetations may also involve the foreign body. In part because the vegetations are larger and the valve can be interrogated from at least five different vantages, transthoracic echocardiography more reliably detects tricuspid valve infection than either mitral or aortic. The incremental value of transesophageal echocardiography for diagnosis is therefore reduced.138Transesophageal echocardiography, however, is critical for evaluating the mechanism of tricuspid regurgitation: interposed vegetations, disrupted tensor apparatus, or damaged leaflets. ‘

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Management

Whether the infection resides in those who use illicit drugs or drug-free patients, princi4y* lZ1 pal therapy is antibiotic management.20* There is little convincing evidence that either pulmonary embolism or large vegetations should alter this approach. In otherwise uncomplicated tricuspid valve endocarditis, short courses of intravenous antibiotics followed by outpatient oral therapy or oral agents alone are successful and gaining popularity in this era of medical cost containment.”, 50, When there is no compelling hemodynamic imperative, recurrences should also be treated with antibiotics, attending to considerations of emerging antibiotic resistance or a new pathogen.y0Abscesses are rare, involving the interventricular septum when they do occur. Surgery is rarely required acutely, but in persistent infection despite appropriate therapy, either vegectomy or valve excision may assist in obtaining bacterial cure.8,6o If the right ventricle and septum function normally, patients can live for months or even years without the valve and have few if any symptoms, although all eventually develop right ventricular failure.5.8Valve replacement or repair can be postponed and undertaken electively when the patient is clearly cured and social rehabilitation ensured.2,29, 31* ’01, 116, lI7, 142 Rheumatic Tricuspid Valve Disease

when pressures are measured directly at catheterization, significant stenosis may not be evident without the use of volume stress.48* 119,161 In contrast to the mitral valve in which pure stenosis occurs with little if any regurgitation, significant regurgitation is common for the tricuspid valve limiting the use of balloon valvotomy. Echocardiography

Echocardiography shows echodense leaflets that are thick with limited, almost mechanical motion.”’, 164 Coaptation is often incomplete, accounting for the regurgitation. Doppler interrogation identifies whether stenosis or regurgitation is more prominent, although mixed disease complicates the analysis. Management

Management of the tricuspid disease by itself almost always involves treating the patient symptomatically and repairing associated lesions. When severe tricuspid stenosis or insufficiency accompanies mitral stenosis, the tricuspid valve should be replaced. Correcting the mitral lesion rarely resolves the tricuspid lesion, and the patient’s exercise capacity remains markedly limited.41,134 The result of mitral valvotomy in reducing pulmonary artery pressures and tricuspid regurgitation may be different in a younger population whose disease is of shorter d ~ r a t i 0 n . l ~ ~

Clinical Features

Acute carditis is uncommon in North America. Its stigmata are evident years after infection affects one or several valves and can produce stenosis or regurgitation, a result of proliferative and exudative inflammation involving collagen. There is diffuse fibrous thickening of leaflets at the margins of closure. Location and extent of leaflet and chordal involvement determine whether stenosis or regurgitation predominates. Chordal fusion and thickening are less severe and calcium deposition less intense in tricuspid than mitral disease. Rheumatic tricuspid valve disease is exceedingly rare as an isolated lesion, and the clinical picture is dominated by manifestations of the mitral valve disease. Stenosis occurs in less than 5% of patients with mitral stenosis, whereas moderate-to-severeregurgitation is present in 35% to 40%.48, Even

Clinical Features

The prevalence of tricuspid prolapse is 0.3% to 3.2% in the general population but 20% in patients with mitral prolapse.” The collagenous degeneration and excess myxomatous tissue results in large, redundant leaflets that prolapse into the atrium. Often the annulus dilates as well. The disorder occurs twice as often in women and accompanies heritable connective tissue disorders such as Marfan’s syndrome. It is also associated with secundum ASDs and Ebstein’s anomaly. Although a clinical syndrome has been described (dizziness, palpitations, and syncope), the diagnosis depends on auscultatory nonejection clicks and a late systolic murmur that varies with respiration.

TRICUSPID VALVE DISEASE

Echocardiography

Echocardiography demonstrates the prolapse, predominantly of the anterior leaflet, seen best in the parasternal images.15The regurgitation is usually mild. Management

Management is seldom necessary except when there is severe regurgitation or endocarditis. Currently, antibiotic prophylaxis is recommended for mitral prolapse with regurgitation or murmur, but not for isolated tricuspid disease. Carcinoid

Clinical Features

Malignant carcinoid generally metastasizes from the small intestine, usually ileum, to the liver. About 50% of patients with spread to the liver exhibit the syndrome of episodic flushing, bronchospasm, and diarrhea. Carcinoid involves the endocardium of the right atrium and ventricle and the pulmonary valve and vessels. Anatomically the white, fibrous plaques sheath the valvular endocardium and chordae, and there is evidence of collagen and smooth muscle cell proliferation.l60, Serotonin (5-HIAA) is the presumed mediator of the fibrous plaques.37 The plaques, most often on the septal and anterior leaflets, result in impaired mobility.55Although either stenosis or regurgitation can occur, the latter is significantly more common. Patients with valvular manifestations have higher levels of serotonin metabolites than those without and have a poorer progno~is.55~128 Echocardiography

Echocardiography shows leaflet thickening, sometimes producing a club-shaped anterior tricuspid leaflet, and chordal fusion.81,11* Doppler interrogation determines the nature and severity of the valvular lesion. Ultrasonography assists in the detection of endocarditis, a complication of carcinoid valvopathy.95 Management

Management involves treatment of the tumor and palliation of the valvular disease.

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Severe hepatic engorgement is often the most disturbing clinical manifestation. Balloon Valvotomy is preferable to surgery for stenosis because carcinoid lesions can affect bioprosthetic valves, and valvopathy represents an advanced stage of the tumor, however, largely regurgitant tricuspid valves must be re27, 80, Io6 Medical therapy is ineffective placed.22, in preventing progression of carcinoid heart disease. Medication-Induced Valve Disease

Clinical Features

Medications have historically been a rare cause of valvular, particularly tricuspid valve, disease. Two classes of drugs have been associated with valve disease-therapy for migraine headaches, including methysergide and ergotamines, and anorectics, most recently the combination of dexfenfluramine or fenfluramine and phentermine, or the former agent Ergotamines and methysergide rarely involve the right side of the heart. The lesions are similar to those found in carcinoid 51 The structural homology of heart disease.47, serotonin with these drugs forms the presumed link. Both the endocardia1 and the Valvular lesions are similar to carcinoid, encasing then distorting leaflets and tensor apparatus. The anorectic (dex)fenphen combination results in both primary valvular disease and pulmo25, 88, 153 Tricuspid disease nary hypertension.l4< did not occur alone but was seen almost exclusively in patients with serious left-sided valvular heart disease or pulmonary hypertension.25One series shows a higher proportion of anatomic tricuspid disease and demonstrates histopathology similar to carcinoid. In this series, referred for clinical findings, the incidence of serious valvular disease requiring intervention was high. Other medications, including amphetamines, cocaine, and toxic oil, cause pulmonary hypertension and cause right ventricular failure and tricuspid regurgitation with normal leaflets.&,139 Echocardiography

Echocardiography parallels pathoanatomy. The septal leaflet is thickened and may be adherent to the endocardium; movement of the anterior leaflet was restricted and doming described. This combination resulted in a failure of the valve to coapt properly with resulting ins~fficiency.~~

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Management

lation between the number of biopsies and the likelihood of moderate-to-severe regurgiErgot alkaloids have largely been replaced t a t i ~ n .149 ~~, by other migraine remedies, although some Electrodes cause tricuspid regurgitation by of these operate by altering serotonin levels. restricting leaflet or chordal mobility or leaflet The anorectic combination has been withperforation or in association with infective drawn from the market, although phenter131, 136 Restricted movement selend~carditis.~~, mine is available and may still be implicated. dom results in significant regurgitation. EnAs yet, the prevalence of serious valvular disdocarditis may involve the leaflets or the elecease or pulmonary hypertension is not trode and generally requires device removal known. A series of recommendations is being as well as antibiotic therapy4,68 Insufficiency considered for the use of echocardiography is more common when patients are paced and for antibiotic prophylaxis in patients exfrom the ventricle (nonsynchronous atrial posed to anorectic drugs in this class. Until contraction) than with synchronous atrioventhese are published, any patient exposed to tricular activation, but even in the absence of the drug combination or either alone with tricuspid insufficiency, the examiner may be symptoms or murmur should be referred for misled by the jugular venous pulsations.39,y8 echocardiography and followed at 6- to 12Echocardiography provides an anatomic asmonth intervals. sessment of the cause in blunt chest trauma. TEE can discriminate among leaflet, chordal, and papillary muscle injury and guide deciTrauma sions regarding valvular repair or replacement. Some authors have suggested its use Clinical Features to guide posttransplant biopsies, preventing Three types of trauma may result in tricusaccidental injury to the valvular apparatusP pid insufficiency: blunt chest trauma, compliFor device-related endocarditis, careful examcations of cardiac transplantation, and elecination of the valve and electrode usually retrode placement for implantable pacing or quires the transesophageal approach when cardioverting devices. In a Mayo Clinic resignificant tricuspid insufficiency arises, espeview, less than 1%of tricuspid valve replacecially with suspected infection. Vegetations ment was the result of blunt chest trauma.157 may appear on the leaflets, electrode, or both, The presumed mechanism is a sudden rise in and myocardial abscess has been reported. right ventricular pressure because of comGenerally the device must be removed to cure pression of the thorax. This causes strain on the infection regardless of the site of the vegethe tensor apparatus and leaflets. Most often, tation. the injury involves the chordae or papillary muscles, but injury to the interatrial septum with right-to-left shunting has also been reMyocardial Infarction ported; cyanosis may also occur when a jet of insufficiency crosses a patent foramen ~ v a l e . ~ , Clinical Features 76,99,163 The initial cardiac injury may go unrecognized because of accompanying trauma, Acute right ventricular infarction often reand it may be months or years before the sults in hypotension and on occasion cardioconsequences of the induced injury is evigenic shock. Generally associated with infedent.54van Son et a1 reported a median time rior wall injury and right coronary artery between injury and presentation of 17 occlusion, its occurrence increases overall risk years.157 of significant myocardial events. The shock Tricuspid insufficiency after cardiac transsyndrome with right ventricular infarction plantation may result from distortion of the usually represents a low-output state retricuspid annulus or later and progressively sulting from extensive right ventricular and after multiple endomyocardial biopsies.59,118, septa1 injury or even aneurysm formation.26 159, 166 It has been proposed that the tricuspid In some cases, however, tricuspid regurgitaannulus is shifted in the transplanted heart 43* 151 Dobutamine tion contributes as resulting in more direct access of the biopincreases cardiac output and stroke volume tome to the valvular apparatus. In addition, in patients with ischemic right ventricular chordae arise from the septum, a favored bidysfunction, but not when significant tricusopsy site.12Two studies demonstrate a correpid regurgitation is present.28 Chordal rup-

TRICUSPID VALVE DISEASE

565

ture, papillary muscle rupture, and extensive injury to the posterior septum and right ventricular free wall have all been described as causes in the setting of ischemic disease. Echocardiography demonstrates the pathoanatomy, revealing enlarged right ventricle with regional dysfunction or papillary muscle injury and showing the severity of the valvular ins~fficiency.'~~ In most cases, left ventricular function is not severely impaired.2s

the downstream side of leaflets than with infectious endocarditis and may involve the tensor apparatus as well.

Management

Tumors and Thrombi

Most cases require only transient support with inotropes, but when hypotension persists or right ventricular failure develops early or later, surgical intervention may be warranted.61,150 Antiphospholipid Syndrome

Clinical Features The antiphospholipid syndrome (APS) is defined by the presence of antiphospholipid antibodies and venous or arterial thrombosis, recurrent pregnancy loss, or thrombocytopenia. It has been associated with a variety of connective tissue disorders, occurs sporadically, and occurs as part of paraneoplastic syndromes. Echocardiographic studies have disclosed heart valve abnormalities in about 56 Sysa third of patients with primary APS.38* temic lupus erythematosus patients with antiphospholipid antibodies have a higher prevalence of valvular involvement than those without these antibodies.lz9Valves affected in patients with antiphospholipid antibodies have either masses (nonbacterial vegetations) or thickening. The predominant functional abnormality is regurgitation. The mitral and aortic valves are most often affected. In one publication, the tricuspid valve was more often echocardiographically abnormal (4% of patients) than in matched controls; however, mitral or aortic abnormalities were present in 61% of patients. Cerebral thromboembolism occurs almost exclusively in patients with valvular involvement. Pulmonary thrombosis or thromboembolism has been reported in patients with APS and may result in pulmonary hypertension with secondary tricuspid regurgitation. Echocardiography Echocardiography shows valve thickening or vegetations. The latter are more often on

Management Currently, there is no specific management except for antiplatelet therapy and treatment of the underlying disorder.

Clinical Features Primary (lipomas, myxomas, chondromas, sarcomas, rhabdomyomas) and secondary (metastatic myomas, melanoma) tumors and thrombi may cause intermittent or chronic valvular obstruction and syndromes combining features of tricuspid stenosis with pulmonary embolism similar to infective endocarditis.* Rhabdomyomas in infants can be associated with tuberous sclerosis and preexcitation syndromes, and lipomatous tumors of the valves may have pulmonary embolism. Thrombi may mimic tumors, especially myxomas, in immunologic syndromes (systemic lupus, vasculitis) and on pacing electrodes and may become secondarily infected.73,I3O, 149 Persistent trauma to leaflets from thrombi or tumors may cause sufficient damage to require repair or replacement. Echocardiography Echocardiography can effectively detect masses and often the sites from which they arise. The technique is unreliable for distinguishing histopathology, although certain pathoanatomic features suggest specific diagnoses. Insufficiency with Normal Leaflets

Pathophysiologic Principles Tricuspid leaflets are anatomically normal in this group of disorders. The principal disease entity determines the dominant clinical features in functional tricuspid regurgitation. All are characterized by pulmonary hypertension of varying degrees, typically (but not invariably) most severe in primary pulmo*References 10, 17, 30, 70, 93, 114, 129, 145, 149, 158.

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nary hypertension and mitral stenosis and less so in chronic mitral regurgitation or pulmonary diseases. Ordinarily the impedance of the normal pulmonary circulation is one eighth that of the systemic arterial circulation. At lower blood flow and lung volumes, resistance remains low and even drops because of recruitment of underperfused vessels and distention of extraparenchymal vessels. It is not, however, a particularly elastic circulation because it is largely intraparenchymal. Distention is therefore opposed by surrounding alveoli, and at higher lung volumes (e.g., emphysema) or higher pulmonary vascular pressures, the circulation is not compliant, and impedance rises sharply. Acting separately or in concert, vasoconstrictor influences (alveolar hypoxia and acidosis), and changes in vessel architecture (obstruction or destruction by parenchymal lung diseases) reduce vascular cross-sectional area, causing or contributing to pulmonary hypertension. For simplicity, causes of pulmonary hypertension are classified as precapillary and postcapillary. Precapillary causes primarily involve the parenchymal vessels (e.g., primary pulmonary hypertension and pulmonary diseases) and are characterized by elevated pulmonary vascular resistance with normal pulmonary venous pressure. In contrast, pulmonary venous pressure is elevated with postcapillary causes such as mitral valve disease or left ventricular failure, although there may be a separate pulmonary vascular (reactive) component as well. Elevated pulmonary vascular resistance induces changes in right ventricular function and, over a longer period, structure and geometry. The acute application of even a modest pulmonary vascular load on a previously normal right ventricle reduces stroke volume sharply and may result in acute tricuspid regurgitation. If applied gradually and progressively, the right ventricle remodels and capably sustains function until failure supervenes. At this point, the right atrium, ventricle, and tricuspid annulus dilate producing an orifice larger than the pulmonary outflow tract, and tricuspid insufficiency dominates the hemodynamic picture. The diagnosis of pulmonary hypertension, regardless of cause, ultimately depends on direct pressure measurements for accurate quantification and physiologic assessment. Helpful but inconsistent features on examination (right ventricular prominence, accentuated S,P), electrocardiogram (see later), and

chest radiography (right main pulmonary artery >16 mm, left >18 mm often with underperfusion more peripherally) have given way to Doppler assessment. By quantifying velocity profiles of tricuspid regurgitation, converting the peak velocity to pressure using an (over)simplified version of the Bernoulli equation, and adding an estimate of right atrial pressure, one can derive an estimate of peak right ventricular pressure and in the absence of pulmonic stenosis therefore peak pulmonary artery pressure. Although correlations with actual measurements have generally been good, the absolute agreement is considerably less accurate, and both overestimates and underestimates have been well documented in the literature. Errors result from inadequate interrogation or alignment with the regurgitant jet, the inability of the simplified approach to account for different degrees of regurgitation, estimates of the correction for atrial pressures, and the impact of orifice geometry. A more qualitative sign is rapid acceleration and deceleration or midsystolic notching of the pulmonary valve velocity profile. Even allowing for inaccuracies, however, Doppler estimates are helpful at least in a semiquantitative way. Acute Massive or Large Pulmonary Embolism The patient is breathless, often transiently hypotensive, and cyanotic. Examination may show regurgitant waves in the jugular venous pulses and a systolic murmur along the left sternal border. An accentuated pulmonic closure may precede aortic closure. A large pulmonary embolism induces right ventricular pressure loading and alveolar hypoxia. If sufficient, the load dilates the right ventricle and, combined with the hypoxia, incites myocardial ischemia leading to acute tricuspid regurg i t a t i ~ n .79,~ 91 ~ ,As a result, the electrocardiogram shows right ventricular strain. Forward stroke volume falls, reducing cardiac output and aortic pressure and decreasing coronary perfusion pressure. Coronary flow through the right coronary artery decreases as the vasodilatory reserve is exhausted. Echocardiography shows evidence of acute cor pulmonale: ventricular interaction, right ventricular dilation with dysfunction primarily of the free 63, 64, 79, 91 wall, and valvular regurgitati~n.~~, Analysis of jet velocity confirms and quantifies pulmonary hypertension, which may be higher in patients with right ventricular hy-

TRICUSPID VALVE DISEASE

pertrophy owing to chronic cardiopulmonary disease. The findings of right ventricular dilation, tricuspid insufficiency, and limitation of left ventricular filling portend a poor prognosis and mandate thrombolytic therapy or thrombectomy. Chronic Pulmonary Diseases Diseases that result in sustained hypoxia ultimately effect changes in pulmonary architecture, increase pulmonary vascular resis~ ~Io9, When tance, and result in coy p ~ l r n o n a l e .84, sustained, right ventricular failure and tricuspid regurgitation mark the terminal phase of cor pulmonale, and the patient exhibits symptoms of low output and systemic venous congestion. Using broad categories, disorders include those of the neuromuscular apparatus and chest wall, impaired ventilatory control, central airway obstruction, and chronic restrictive and obstructive parenchymal diseases. The physical examination in these patients may be difficult to interpret because wide swings of intrathoracic pressures alter assessment of jugular venous waveforms, chest wall configuration may interfere with adequate auscultation, and pathologic lung sounds may mimic those of left-sided heart disease.53The electrocardiogramoften but not invariably shows rightward QRS axis, SIQ3 or S1S2S3pattern, P-pulmonale or rightward P vector, and R/S in V, greater than 1. Low voltage, complete right bundle-branch block, and pseudoinfarct patterns are more common in chronic obstructive diseases.ll Cardiac ultrasound directly measures right atrial and ventricular size and geometry in many patients, but acoustic access to cardiac and vascular structures may be limited by chest wall deformities and pulmonary fibrosis or hyperaeration. The right ventricle is systematically larger and pulmonary pressures higher in patients with advanced chronic airways disease. There is no reliable correlation, however, between either of these variables and the degree of desaturation or nocturnal desaturation. Left ventricular geometry, systolic function, I4O Doppler and filling may also be impaired.97, estimates of pulmonary artery pressures assist in determining whether pulmonary pressures are elevated and the degree of tricuspid regurgitation. Other Causes of Pulmonary Hypertension Elevated pulmonary pressures result from primary or secondary abnormalities of the

567

pulmonary circulation. A small number of patients have either an inherited or sporadic genetic cause or tendency identified clinically by a surprisingly consistent set of clinical features grouped as primary pulmonary hypertension. Abnormal vasoreactivity and structural obliteration (muscular, fibrotic, and thrombotic) contribute to pulmonary vascular obstruction and ultimately marked elevation of pulmonary pressures. In addition to a familial tendency, some have other predisposing factors: exposure to anorectics, systemic hypertension, elevated pulmonary blood flow, and portal hypertension. Arteritis, veno-occlusive disease, and capillary hemangiomatosis may also affect the pulmonary circulation primarily. Syncope and exercise intolerance begin at a relatively young age in women much more often than men. The exercise intolerance reflects both underfilling of a stiff, hypertrophied right ventricle and afterload excess as pulmonary pressures rise further with higher pulmonary blood flow. Almost half of patients die of progressive right heart failure with accompanying tricuspid regurgitation. Right ventricular failure is probably ischemic from a reduced central aortic and therefore coronary driving pressure and severe pressure overload. Left ventricular systolic and diastolic failure, regardless of cause, eventually elevates pulmonary artery pressures and causes right 11, 33, 67,75* 89, 133* The develventricular fail~re.~, opment of tricuspid regurgitation portends a poorer prognosis. Some of the causes have been discussed here, but more detailed analysis is well beyond the focus of this article. References 1. Akasaka T, Yoshikawa J, Yoshida K, et al: Agerelated valvular regurgitation: A study by pulsed Doppler echocardiography. Circulation 76262-265, 1987 2. Allen MD, Slachman F, Eddy AC, et a1 Tricuspid valve repair for tricuspid valve endocarditis: Tricuspid valve "recycling." Ann Thorac Surg 51:593598, 1991 3. Appleton CP, Hatle LK, Popp RL: Demonstration of restrictive ventricular physiology by Doppler echocardiography. J Am Coll Cardiol 11:757-768, 1988 4. Arber N, Pras E, Copperman Y, et al: Pacemaker endocarditis: Report of 44 cases and review of the literature. Medicine 73299-305, 1994 5. Arbulu A, Holmes RJ, Asfaw I: Tricuspid valvulectomy without replacement: Twenty years' experience. J Thorac Cardiovasc Surg 102917-922, 1991 6. Bagger J P Modification of myocardial biopsy technique with long sheath [letter]. Am J Cardiol 78:860, 1996

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7. Banning AP, Durrani A, Pillai R Rupture of the atrial septum and tricuspid valve after blunt chest trauma. Ann Thorac Surg 64:240-242, 1997 8. Barbour DJ, Roberts WC: Valve excision only versus valve excision plus replacement for active infective endocarditis involving the tricuspid valve. Am J Cardiol 57:475478, 1986 9. Bayer AS, Bloinquist IK, Bello E, et al: Tricuspid valve endocarditis due to Staphylococcus aureus: Correlation of two-dimensional echocardiography with clinical outcome. Chest 93:247-253, 1988 10. Benvenuti LA, Mansur et al: Primary lipomatous tumors of the cardiac valves. South Med J 89:10181020, 1996 11. Braunwald E (ed): Heart Disease: A Textbook of Cardiovascular Medicine, ed 5. Philadelphia, WB Saunders, 1996 12. Braverman AC, Coplen SE, Mudge GH, et al: Ruptured chordae tendineae of the tricuspid valve as a complication of endomyocardial biopsy in heart transplant patients. Am J Cardiol 66:111-113, 1990 13. Breisch EA, Wilson DB, Laurenson RD, et al: Tricuspid atresia (type la): Survival to 21 years of age. Am Heart J 106(1 Pt 1):149-151, 1983 14. Brenot F, Herve P, Petitpretz P, et al: Primary pulmonary hypertension and fenfluramine use [see comments]. Br Heart J 70:537-541, 1993 15. Brown AK, Anderson V Two dimensional echocardiography and the tricuspid valve: Leaflet definition and prolapse. Br Heart J 49:495-500, 1983 16. Burns JM, Hogg KJ, Hillis WS, et al: Endocarditis in intravenous drug abusers with staphylococcal septicaemia. Br Heart J 61:356-357, 1989 17. Carrel T, Linka A: Tricuspid valve obstruction caused by plasmacytoma metastasis. Ann Thorac Surg 54:352-354, 1992 18. Celermajer DS, Cullen S, Sullivan ID, et al: Outcome in neonates with Ebstein’s anomaly. J Am Coll Cardiol 19:1041-1046, 1992 19. Celermajer DS, Dodd SM, Greenwald SE, et a1 Morbid anatomy of neonates with Ebstein’s anomaly of the tricuspid valve: Pathophysiologic and clinical implications. J Am Coll Cardiol 19:1049-1053, 1992 20. Chan P, Ogilby JD, Segal B: Tricuspid valve endocarditis. Am Heart J 1171140-1146, 1989 21. Choi YH, Park JH, Choe YH, et al: MR imaging of Ebstein’s anomaly of the tricuspid valve. AJR Am J Roentgen01 163:539-543, 1994 22. Codd JE, Drozda J, Merjavy J: Palliation of carcinoid heart disease. Arch Surg 122:1076-1077, 1987 23. Come PC: Echocardiographic evaluation of pulmonary embolism and its response to therapeutic interventions. Chest 101(4 suppl):151S162S, 1992 24. Come PC, Riley M F Tricuspid anular dilatation and failure of tricuspid leaflet coaptation in tricuspid regurgitation. Am J Cardiol 55:599-601, 1985 25. Connolly HM, Crary JL, McGoon MD, et al: Valvular heart disease associated with fenfluramine-phentermine [see comments]. N Engl J Med 337581588, 1997 26. DArcy B, Nanda NC: Two-dimensional echocardiographic features of right ventricular infarction. Circulation 65167-173, 1982 27. Defraigne JO, Jerusalem 0, Soyeur D, et al: Successful tricuspid valve replacement and pulmonary valvulotomy for carcinoid heart disease. Acta Chir Belg 96~170-176,1996 28. Dhainaut JF, Ghannad E, Villemant D, et al: Role of tricuspid regurgitation and left ventricular damage

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