EVALUATION OF THE PEDIATRIC PATIENT WITH A CARDIAC MURMUR

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PEDIATRIC CARDIOLOGY

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EVALUATION OF THE PEDIATRIC PATIENT WITH A CARDIAC MURMUR Andrew N. Pelech, MD

This article provides a framework for the general assessment and evaluation of pediatric patients recognized to have cardiac murmurs. Cardiac murmurs are a common finding in children and represent the most frequent reason for referral to a cardiology subspecialist. The majority of these patients can be adequately evaluated clinically, yet increasingly more extensive studies are being used in this assessment. The reasons for this pattern of practice are many, including reduced confidence in auscultatory skills, increased availability of diagnostic technology, the increasingly competitive nature of pediatric practice, and increased medicolegal concerns. The only definitive mechanism of diagnosing an innocent murmur is by physical examination. In the majority of patients with a cardiac murmur, a careful history and physical examination should serve to guide further referral and directed evaluation. An inappropriate echocardiographic assessment may rule out significant structural cardiac anomalies but does not provide parents an explanation for the cause of the cardiac murmur. This has resulted in unresolved patient and parental anxiety and inappropriate limitation from sports involvement or inappropriate use of antibiotic prophylaxis. Potentially problematic are adult echocardiographic laboratories unskilled in the evaluation of congenital cardiac anomalies. These laboratories may perform unsedated and inadequate evaluations that may provide a false impression of the absence of a significant cardiac anomaly. PATIENT AGE AT REFERRAL An understanding of the fetal, transitional, and neonatal adaptations of the circulation is important in the evaluation of the pediatric cardiovascular system

From the Division of Pediatric Cardiology, The Medical College of Wisconsin, Milwaukee, Wisconsin PEDIATRIC CLINICS OF NORTH AMERICA VOLUME 46 * NUMBER 2 * APRIL 1999

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because most organic heart disease is evident in association with the circulatory changes occurring at birth. The majority of significant structural congenital heart disease is recognized in the first few weeks of life.I9 The patient’s age at recognition or referral often dictates the nature of the cardiac anomaly and the urgency with which assessment is necessary. In the fetus (Fig. l), oxygen is derived from the placenta, returns via the umbilical vein and through the ductus venosus to enter the right atrium. Preferentially, flow is directed across the foramen ovale to enter the left atrium and subsequently the left ventricle. Deoxygenated blood returning from the superior vena cava and upper body segment is preferentially directed by the flap of the eustachian valve to enter the right ventricle and then, via the ductus arteriosus, to enter the descending aorta to return via the umbilical arteries to the placenta. The pressures within both ventricles are essentially equal because both chambers pump to the systemic circulation; however, in utero, the right ventricle does the majority of the work, pumping 66% of the combined cardiac At transition, with the first breath, pulmonary arterial resistance begins to decrease and the lungs begin the process of respiration. Pulmonary venous return to the left atrium closes the flap of the foramen ovale. Through mechanical and chemical mechanisms,’ the ductus arteriosus begins to close. In normal term infants, this is normally accomplished by 10 to 15 hours of age. Intermittent right-to-left atrial level shunting through the foramen ovale may occur, particularly if pulmonary vascular resistance fails to decrease. In addition, structural cardiac abnormalities requiring patency of the ductus arteriosus for maintenance of either pulmonary blood flow (e.g., pulmonary atresia) or systemic blood flow (e.g., hypoplastic left heart syndrome) most often present within the first few days of life. Thus, the timing of presentation of pediatric patients for evaluation influences the spectra of heart disease to be considered. Ductal-dependent abnormalities, such as pulmonary atresia, transposition of the great arteries, coarctation of the aorta, hypoplastic left heart, or significant outflow obstructions, such as aortic valve stenosis, present in the first few days of life. In the absence of an associated anomaly, hemodynamically significant ventricular septal defects seldom present before 2 weeks of age. Atrial septal defects are seldom symptomatic in infancy. HISTORY

The historical assessment of pediatric patients referred for the evaluation of cardiac murmurs should include questions about family history, pregnancy, perinatal course, and symptoms of cardiovascular disease in the patient. Structural heart disease is frequently seen in association with recognizable syndromes (Table 1). A family history of sudden death, rheumatic fever, sudden infant death syndrome, or a structural cardiac abnormality in a first-degree relative Figure 1. Fetal (A), transitional (B), and neonatal (C) circulations. The course of the circulation in the heart and great vessels of late gestation in the fetal lamb; a newborn is presented within a few hours of delivery. The figures in the circles within the chambers and vessels represent oxygen saturation percentages. The numbers alongside the chambers and vessels are pressures in mm Hg related to amniotic fluid pressure as zero. DA, ductus arteriosus; Ao, aorta; PA, pulmonary artery; RV, right ventricle; LV, left ventricle; RA, right atrium; LA, left atrium; and DV, ductus venosus. (Adapted from Rudolph AM: Congenital Disease of the Heart. Chicago, Year Book Medical Publishers, 1974, pp 3, 16-19; with permission.)

EVALUATION OF THE PEDIATRIC PATIENT WITH A CARDIAC MURMUR

C Figure 1. See legend on opposite page

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Table 1. SYNDROMES OR SYNDROME COMPLEXES ASSOCIATED WITH CONGENITAL HEART DISEASE Syndrome Alagille (arteriohepatic dysplasia) Asplenia .... Carpenter's CHARGE

......

..............................................

..................................................

Cri-du-chat (deletion 5p) ...................... de Lange's ... DiGeorge ..... Down ........................................................ Ellis-van Creveld Fanconi's .............. Fetal alcohol

......

Fragile X ...... Goldenhar's Holt-Oram ................................................ Hydantoin ................................................ Infant of diabetic mother ...................... Laurence-Moon-Biedl Marfan's ................................................... Mulibrey nanism ..................... Multiple lentigenes (leopard) Noonan's .................................................. Polycystic kidney disease ..................... Polysplenia .............. ...... Rubella

......................................................

Rubinstein-Tayba .................................... Scimitar ..................................................... Smith-Lemli-Opitz

..................................

Thrombocytopenia-absent radius (TAR) Trisomy D ......................................... Trisomy E

........

.................................................

Velocardiofacial ....................................... Williams ................................................... Wolf

Peripheral pulmonary stenosis Complex cyanotic heart disease, anomalous veins, pulmonary atresia Patent ductus arteriosus, ventricular septal defect Ventricular, atrioventricular, and atrial septal defects Variant forms of congenital abnormalities Tetralogy of Fallot, ventricular septal defect Aortic arch anomalies, tetralogy of Fallot Atrioventricular septal defects, ventricular septal defect Single atrium Patent ductus arteriosus, ventricular septal defect Ventricular septal defect, atrial septal defect, tetralogy of Fallot Mitral valve prolapse, aortic root dilation Tetralogy of Fallot Atrial or ventricular septal defect Atrial or ventricular septal defect, coarctation Hypertrophic cardiomyopathy, ventricular septal defect Tetralogy of Fallot, ventricular septal defect Aortic root dissection, mitral valve prolapse Pericardial thickening, constrictive pericarditis Pulmonary stenosis Pulmonic stenosis, atrial septal defect Mitral valve prolapse Complex acyanotic lesions, azygous continuation Patent ductus arteriosus, peripheral pulmonary stenosis Patent ductus arteriosus Hypoplasia of the right lung, anomalous pulmonary drainage Ventricular septal defect, patent ductus arteriosus Atrial septal defect, tetralogy of Fallot Ventricular septal defect, patent ductus arteriosus Ventricular septal defect, patent ductus arteriosus Coarctation of the aorta, bicuspid aortic valve Coarctation, hypoplastic left heart Ventricular septal defect, right aortic arch Supravalvular aortic stenosis, peripheral pulmonary stenosis Atrial septal defect, ventricular septal defect

Data from Bemstein D. The cardiovascular system. In Behnnan RE,Kleigman Rh4, Arvin AM (eds): Nelson's Textbook of Pediatrics. Philadelphia, WB Saunders, 1996, p 1262; and Moss A]: Clues in diagnosing heart disease. West J Med 156395,1992.

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may have diagnostic relevance. In patients suspected to have rheumatic heart disease, the family history is more often positive than that associated with congenital heart disease. A family history of a first-degree relative with hypertrophic cardiomyopathy is associated with such a high incidence of inheritance (> 20%) and may be sufficiently subtle that echocardiographic screening is mandatory.21 A maternal history of gestational diabetes mellitus may be associated with a transient hypertrophic cardiomyopathy in addition to other congenital structural abnormalities in as many as 30% of infants.32Additional relevant pregnancy history may include the presence of chronic or acute maternal illness, congenital infections, or drug use, which may be associated with significant structural heart disease (Table 1). Unexplained fever, lethargy, or recent dental work should arouse suspicion of possible endocarditis. SYMPTOMS AND SIGNS OF HEART DISEASE

The general health of children with suspected cardiac malformations is important. Particularly relevant are the rate of growth and development, and the history of past illnesses. Although symptoms of failure to thrive are nonspecific, patterns of growth reflect duration, severity of the disease, and effectiveness of treatments. In infants, feeding difficulties are often the first evidence of congestive heart failure (CHF).CHF occurs in 30% of infants and children with congenital heart disease.38Feeding problems are common manifestations of cardiac disease and may be evidenced as disinterest, excessive fatigue, diaphoresis or a change in the pattern of respiration, tachypnea, or dyspnea. Obtaining a measure of caloric intake by quantitating number or volume of feedings is important. Some index of exertional tolerance should be sought in all children as an index of cardiovascular fitness and finest sign of functional capability. This should be age relevant and in infants might include assessment of the vigor, duration of feeding, and time period of interactive play. For toddlers, this might include the ability to climb stairs or walk for extended periods, such as in the shopping mall. In older children, a comparison with peer sporting interactions, level of function in physical education, and an index of aerobic ability should be sought. Respiratory rates should be assessed in quiet, fasting infants. The rate and pattern of breathing should be assessed for a full minute because rates may vary considerably with activity and feeding. Tachypnea occurs as a consequence of increased pulmonary blood flow. With increasing pulmonary congestion, particularly obstruction to the pulmonary venous drainage, dyspnea, manifest as grunting, flaring of the alae nasi, and intercostal, suprasternal and subcostal retractions, progressively occurs. Cardiac asthma or exercise inducible reactive airway disease may occur as a consequence of passive or active pulmonary congestion. Compression of airways by plethoric vessels may contribute to stasis of secretions and atelectasis and predispose to respiratory tract infections (RTIs). Cyanosis in association with a cardiac murmur suggests a structural lesion with restriction to pulmonary blood flow. Cyanosis, or a blue skin discoloration evident as a consequence of reduced hemoglobin (> 3-5gmY0) is evident in one third of infants with potentially lethal congenital heart disease.I5Central cyanosis is distinguished from acrocyanosis or peripheral cyanosis by involvement of the warm mucous membranes, including the tongue and buccal mucosa in the former. Acrocyanosis or peripheral cyanosis is generally confined to the perioral, perinasal skin, and nail beds and occurs in children who are cold, vasoconstricted, or at rest. A distinctive feature is that central cyanosis generally worsens with activity and increasing cardiac output, whereas acrocyanosis generally improves or resolves with increased activity.

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PHYSICAL EXAMINATION

Developing an organized routine in the performance of the cardiac examination is necessary so that important points are not missed or neglected. Although aspects of the examination may sometimes be performed out of order, such as auscultating the sleeping infant when the opportunity arises, an effort should be made to perform all aspects of the physical examination in every patient. In each routine examination, critical evaluation of signs should be performed so that when an abnormality arises, it is readily recognized. Examination of toddlers may be best performed on their parents' laps. In older patients, allowing a few minutes of conversation with the parents or child to gain the child's confidence is often best. OVERALL APPEARANCE

The height and weight should be measured and plotted on a growth An assessment of the child's overall growth, appearance, and state of distress serves to guide the urgency of further investigation and management. Sick infants often appear anxious, fretful, diaphoretic, pale, or breathless and are seldom consolable. Evidence of cyanosis, pallor, clubbing, pattern of respiration, and possible dysmorphic features that may suggest specific structural cardiac anomalies should be looked for. VITAL SIGNS

Vital signs should be recorded for each patient, most comparably and reproducibly in the resting state. Normal resting heart and respiratory values for age are presented in Table 2. Appropriately sized cuffs, in which the width of the inflatable bag covers two thirds of the full length of the arm or in which just enough room is left for the application of the head of the stethoscope, should be used to ensure accurate blood pressure measurement. In general, blood pressures obtained by palpation or the flush technique are significantly less accurate than auscultation. The blood pressure cuff should be applied snugly because more pressure may have to be applied to occlude arterial flow with a loose-fitting cuff. The systolic pressure is recorded as the first audible Korotkoff sound, with the diastolic pressure correlating best with the muffling phase or fourth Korotkoff sound.6Increasingly, automated oscillometric methods allowing digital printouts of systolic, mean, and diastolic pressures are being used for blood pressure meas~rernents.'~ This is generally reliable, although inaccuracies Table 2. NORMAL VALUES OF RESPIRATORY AND HEART RATES IN INFANTS AND CHILDREN Rate

Birth4 wk

6wk-2y

40/min Respiratory 45-60/min Heart 125230/min 115&25/min

2-6 Y

6-1Oy

Over10y

30/min 100t20/min

25/min 902 15/min

20/min 8 5 a 15/min

Data from Bemstein D. The cardiovascular system. In Behrman RE, Kleigman RM, Arvin AM (eds): Nelson's Textbook of Pediatrics. Philadelphia, WB Saunders, 1996, p 1266; and Duff DF, McNamara DG: History and physical examination of the cardiovascular system. In Garson A, Bricker JT, McNamara DG (eds): The Science and Practice of Pediatric Cardiology. Philadelphia, Lea and Febiger, 1990, p 674.

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can occur with movement. Every child should have a comparison of upper and lower blood pressures on at least one occasion in their lives. This is generally performed most reproducibly by calf cuff application to the upper leg and Doppler assessment of the popliteal systolic pressure. Because of the artifact of reflectance waves or filtering of the lower-frequency components of the complex arterial pulse waveform, the lower-limb systolic blood pressure is normally 10 mm Hg higher than the upper-limb pressure. Because the subclavian arteries sometimes arise aberrantly beyond the site of ductal ligament insertion, both upper-limb pressures should be measured and compared with the lower-limb pressure. Normal values for blood pressure in children are presented in Figure 2. RESPIRATORY ASSESSMENT

A review of the respiratory system should be a part of any assessment of the cardiovascular status. In addition to noting the rate, depth, and effort of respiration, the inspection should include observation for evidence of air trapping, increased chest diameter, or the presence of Harrison’s sulci as an indication of chronic upper airway ob~truction.~ An allergic malar facies may also suggest upper airway obstructive disease with predisposition to hypercapnea and associated pulmonary hypertension. CARDIOVASCULAR ASSESSMENT Arterial Examination

Pulses should be assessed for rate, rhythm, volume, and character. The dynamic character of the pulse may provide information about the cardiac output. A clinical index of cardiac output includes the warmth of the digits and measured capillary refill time. This is obtained by blanching the nail bed or digit and estimating the time to full reperfusion, normally less than 2 or 3 seconds.34 Initially, the radial and brachial pulses should be assessed simultaneously in the upper limb (Fig. 3). By palpating the pulse at two sites and altering the pressure applied by the palpating fingers, a more accurate assessment of the rate of arterial pressure rise, volume, and contour may be obtained. Assessment of the femoral pulse requires that infants be quiet or at least happy. Palpating parallel to the inguinal crease and allowing the leg to continue to flex is generally less disturbing than extending and holding the limb for a perpendicular approach. Whenever possible, the radial pulse should be brought in close apposition to the femoral pulse to compare for any delay (Fig. 4).This enables a more accurate appreciation of any temporal delay and enables more accurate detection of the presence of coarctation of the aorta. The presence of a palpable femoral pulse is an inadequate screen for coarctation because collateral vessels, particularly in older children, may provide delayed perfusion. Previous arterial instrumentation, injury, or congenital variability may account for a reduction in palpable peripheral pulses. Venous Examination

The jugular venous pulse as an index of right atrial pressure elevation is generally difficult or impossible to assess in infants and children. It is a skill

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PERCENTILE

95 90 75 50 25 10 5

95 90 75 50 25 10 5

2

A

4

6

8

10

12

14

16

18

AGE

Figure 2. Normal blood pressure percentiles for (A) boys and (B) girls, aged 2 to 18 years. Korotkoff IV used for diastolic BP. (Courtesy of The National High Blood Pressure Education Program, The National Heart, Lung and Blood Institute, Bethesda, MD. Report of the Second Task Force on Blood Pressure Control in Children, 1987. Pediatrics Vol 79:1, 1987). Illustration continued on following page

that requires considerable experience to interpret and p e r f e ~ t In . ~ infants and small children, the liver character and size offer a more reliable indicator of systemic congestion. The position, size, and consistency of the liver should be assessed. The abdominal examination is best performed in a patient, unhurried manner. By gently palpating for the tone of the rectus muscles, the lateral margin in the midclavicular line can be located. The liver edge can be located and felt by uplifting the fingers with quiet inspiration. The character of the normal liver margin is generally likened to the cartilage of the external auricular pinna and should be sharp and angulated. In newborns, the liver may be normally palpable at 2.5 cm to 3.0 cm below the right costal margin in the midclavicular line. This decreases to approximately 1 cm to 2 cm by 1 year of age and remains just palpable to school age. In the presence of CHF, the liver enlarges and distends

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PERCENTILE

95 90

75 50 25

10 5

2

4

B

6

8

10

12

14

16

18

AGE Figure 2. Continued

downward. The congested liver margin becomes rounded and firm and may often be more difficult to feel. An enlarged liver may be tender, and aggressive palpation may cause discomfort and tensing of the abdominal musculature, making accurate assessment difficult or impossible. The enlarged spleen should always be sought and suggests endocarditis in patients with heart murmurs. Splenic enlargement in association with CHF is unusual. Precordial Examination Inspection of the chest may suggest the presence of a precordial bulge of longstanding right ventricular volume overload. The entire palm and hand should be warmed and then fully applied to the chest wall to maximize the ability to detect thrills or heaves. Whereas the fingertips are best used to localize an abnormality, the palmar surface of the metacarpals and first phalanges are more sensitive for the detection of low-frequency events. The fingertips should

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Figure 3. Simultaneous palpation of the radial and brachial pulse allows better appreciation of rate of rise, pulse volume, and presence of notching. (Adapted from Constant J: Arterial pulses and pressures. In Bedside Cardiology, 4th Ed. Boston, Little, Brown and Company, 1993, pp 30, 59; with permission.) Figure 4. Close approximation of the radial and femoral pulses optimizes ability to detect pulse waveform delay.

be used to localize the most lateral displacement of the apical impulse. At all ages, the apical impulse should be confined to one intercostal interspace and would be described as diffuse if equally dynamic in two or more interspaces. The lateral displacement of the apex should be compared with existing landmarks and is normally located in the midclavicular line. A dynamic or thrusting character apical impulse may be detected in association with an elevated cardiac output or various forms of obstruction to left ventricular outflow. Occasionally, an apical filling impulse, coinciding with an audible third heart sound (S3), may be detected normally, particularly in adolescents or athletes with a relative bradycardia and increased stroke volume. A thrill, or palpable murmur, should be sought in the precordial and suprasternal areas. Although the palmar surface of the hand is most sensitive for the detection of a thrill, only the tips of the digits fit in the suprasternal notch. Rarely, a palpable second heart sound (52)indicative of a significant level of pulmonary hypertension may be detected as a sharp or distinctive impulse in the pulmonary outflow. In general, percussion of the heart is of negligible diagnostic value. Auscultation

No other specialty demands the auscultatory skills to the degree of pediatrics. The majority of structural cardiac abnormalities and virtually all innocent

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murmurs are detected in pediatric patients. Auscultatory skills and confidence may be acquired through an understanding of cardiac mechanics, proper techniques, and training and sustained through continued application. Computeraided instructional auscultation programsz8 are increasingly available and valuable as a source of high-fidelity, digitally recorded sounds and graphic instruction. Auscultation of infants and children should be performed under optimal conditions in the supine, sitting, and standing positions. The ability to detect subtle sounds in the accompaniment of ventilators, incubators, monitors, and active siblings is limited. The examining physician should develop a routine of listening systematically to all components of the cardiac cycle and all auscultatory areas with both the bell and diaphragm. As is described later for innocent murmurs but equally applicable in organic or pathologic murmurs, the effects of dynamic maneuvers (including respiration, Valsalva, exercise, and postural changes) provide important diagnostic information.16,35, 36 When first auscultating the patient, attention should be directed toward the normal heart sounds in sequence. The effects of inspiration and expiration on the heart sounds should be appreciated. Additional heart sounds and murmurs should then be addressed. Any variability that occurs with a change of body position should be described. First Heart Sound

The first heart sound (Sl) arises from closure of the atrioventricular (mitral and tricuspid) valves in early isovolumic ventricular contraction and consequently is best heard in the tricuspid and mitral areas. Mitral valve closure occurs slightly in advance of tricuspid valve closure, and occasionally near the lower left sternal edge two components (splitting) of the S1 may be heard. Normally, it is heard as a single sound. The S1 is most easily heard when the heart rate is slow because the interval between the S1 and S2 is clearly shorter than the interval between the S2 and subsequent S1. The intensity of the S1 is influenced by the position of the atrioventricular valve at the onset of ventricular contraction. If the valve’s leaflets are far apart, the increased excursion to accomplish valve closure increases the intensity of the S1. Second Heart Sound

Shortly after the onset of ventricular contraction, the semilunar valves (aortic and pulmonary) open and permit ventricular ejection. Normally, this opening does not generate any sound. The atrioventricular valves remain tightly closed during ventricular ejection. As ventricular ejection nears completion, the pressure begins to fall within the ventricles, and the semilunar valves snap closed. This prevents regurgitation from the aorta and pulmonary artery back into the heart. The closure of the semilunar valves generates the S2. Normally, the second heart sound consists of a louder and earlier aortic valve closure followed by a later and quieter pulmonary valve closure sound. One can appreciate normal physiologic splitting or variability most easily in the pulmonary area during or near the end of inspiration. During expiration, the aortic and pulmonary valves close almost synchronously and produce a single or narrowly split S2. Normal splitting of the S2 is caused by (1)increased right heart filling during inspiration because of increased blood volume returning via the vena cava and

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(2) diminished left heart filling because blood is retained within the small blood vessels of the lungs when the thorax expands. During inspiration, when the right ventricle is filled more than the left, it takes slightly longer to empty. This causes the noticeable inspiratory delay in pulmonary valve closure relative to aortic valve closure. Splitting of the S2 during inspiration is thus a normal finding and should be sought in all patients. Classification of Cardiac Murmurs

Heart murmurs, audible sound waves in the range of 20 Hz to 2000 Hz, are the consequence of turbulent blood flow; however, not all cardiac murmurs indicate structural or physiologic cardiac problems. One should be able to determine and describe the following characteristics of heart murmurs: Timing: The relative position within the cardiac cycle and with relationship to S1 and S2 Intensity or loudness: Murmurs are graded as: Grade 1: Heard only with intense concentration Grade 2: Faint, but heard immediately Grade 3: Easily heard, of intermediate intensity Grade 4: Easily heard and associated with a thrill (a palpable vibration on the chest wall) Grade 5: Very loud, thrill present, and audible with only the edge of the stethoscope on the chest wall Grade 6 Audible with the stethoscope off the chest wall Location on the chest wall with regard to: Area where the sound is loudest (point of maximal intensity) Area over which the sound is audible (extent of radiation) Duration: The length of time of the murmur from beginning to end Configuration: The dynamic shape of the murmur Pitch: The frequency range of the murmur Quality: The presence of harmonics and overtones

Systolic Murmurs Systolic murmurs begin with or follow the S1 and end before the 52 (Fig. 5). They may be classified as: Holosystolic murmurs: Begin abruptly with S1 and continue at the same intensity to S2; can be shown graphically as a rectangular symbol. This murmur occurs when a regurgitant atrioventricular valve is present (tricuspid or mitral) or in association with the majority of ventricular septal defects. Ejection murmurs: Crescendo-decrescendo or diamond-shaped murmurs that may arise from narrowing of the semilunar valves or outflow tracts. The rising and falling nature of the murmur reflects the periods of low flow at the beginning and end of ventricular systole. Innocent murmurs are almost exclusively ejection systolic in nature. They are generally soft, never associated with a palpable thrill, and are subject to considerable variation with positioning changes. Early systolic murmurs: Start abruptly with S1 but taper and disappear before the S2 and are exclusively associated with small muscular ventricular septal defects.

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Figure 5. Four types of systolic heart murmurs. The holosystolic or pan-systolic murmur begins abruptly with the first heart sound and proceeds at the same intensity to the second heart sound. The ejection systolic or crescendo-decrescendo murmur begins with the onset of volume ejection from the heart. As the flow increases, the murmur varies both in intensity and frequency, and subsequently tapers as the period of ejection ceases before the second heart sound. Early systolic murmur begins as does the holosystolic murmur, abruptly with S1, but terminates in midsystole with the cessation of shunt flow. Late systolic murmur begins well after S1, commencing in mid- to late-systole in association with the development of valve insufficiency and proceeds at this intensity to S2. (From Pelech AN: The cardiac murmur. Pediatr Clin North Am 45(1):107-122, 1998; with permission.)

Mid-to-late systolic murmurs: Begin midway through systole and are often heard in association with the midsystolic clicks and insufficiency of mitral valve prolapse. Diastolic Murmurs

Diastole, the period between closure of the semilunar valves (S2) and subsequent closure of the atrioventricular valves (Sl), is normally silent because of little turbulence associated with low-pressure flow through relatively large valve orifices; however, regurgitation of the semilunar valves, stenosis of an atrioventricular valve, or an increased flow across an atrioventricular valve can all cause turbulence and may produce diastolic heart murmurs (Fig. 6). Early diastolic murmurs are decrescendo in nature and arise from either aortic or pulmonary valve insufficiency (regurgitation). Mid-diastolic murmurs

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Figure 6. The early diastolic or decrescendo murmur occurs in association with closure of the semilunar valves (52) and tapers through part or all of diastole. The mid-diastolic murmur rises and falls in intensity with atrial volume entering the ventricle. The late systolic or crescendo diastolic murmur occurs late in diastole with atrial contraction, prior to systole and ascends to the first heart sound. (From Pelech AN: The cardiac murmur. Pediatr Clin North Am 45(1):107-122, 1998; with permission.)

are diamond shaped and occur because of either increased flow across a normal tricuspid or mitral valve or normal flow across a n obstructed or stenotic tricuspid or mitral valve. Late diastolic or crescendo murmurs are created by stenotic or narrowed atrioventricular valves and occur in association with atrial contraction. Continuous Murmurs

Flow through vessels or channels or communications beyond or distal to the semilunar valves is not confined to systole and diastole. Thus, turbulent flow may occur throughout the cardiac cycle. The resulting murmurs extend up to and beyond the S2 (Fig. 7). Continuous murmurs can be heard through part or all of diastole. Continuous murmurs are generally pathologic. The venous hum is a notable exception. PEDIATRIC MURMUR EVALUATION

Beyond the newborn period, a normal murmur may be detected in the The clinical diagnosis of a normal or majority of children before school

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s1

I

I

181

s2

I

I I 1

I I 1

I

S Figure 7. The continuous murmur begins in systole and proceeds up to and though the second heart sound proceeding through part or all of diastole. (from Pelech AN: The cardiac murmur. Pediatr Clin North Am 45(1):107-122, 1998; with permission.)

innocent murmur should occur in the setting of an otherwise normal history, physical examination, and appearance. Thorough auscultation in cooperative patients should include listening in the principal areas of the precordium (i.e., tricuspid, pulmonary, mitral, and aortic valves) with both the bell and diaphragm with the patient in the supine, sitting, and standing positions. Four areas serve as a guide to auscultation of the heart (Fig. 8). These are the optimal sights for listening to sounds that arise within the chambers and great vessels. Physicians should not feel constrained by these guidelines and should also listen between and beyond these areas: 1. The tricuspid area is represented by the fourth and fifth intercostal spaces along the left sternal edge but often extends to the right of the sternum and downward to the subxiphistemal area. 2. The pulmonary area is the second intercostal space along the left sternal border. Murmurs that are best heard in this area may also extend to the left infraclavicular area or often lower, along the left sternal edge to the third intercostal space. 3. The mitral area involves the region of the cardiac apex, and generally is at the fifth intercostal space in the midclavicular line. This area may also extend medially to the left sternal edge and also laterally to the region of the axilla. 4. The aortic area, although centered at the second right intercostal space, may extend to the suprastemal area and neck and inferiorly to the third left intercostal space. The margins of these areas are ill defined, and auscultation should not be limited to these sites but may extend to the axillae, neck, back, or infraclavicular areas.

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/

area

Tricuspid

area Figure 8. The four primary areas of auscultation represent the general regions where heart sounds and murmurs of the four cardiac valves are often best heard and defined. Note that the areas overlap considerably and that sounds and murmurs are not limited to these sites, often extending to the lateral chest wall, abdomen, and back. (From Pelech AN: The cardiac murmur. Pediatr Clin North Am 45(1):107-122, 1998; with permission.)

No matter how experienced the examiner, step-by-step auscultation first for heart sounds, subsequently for systolic murmurs, and then separately for diastolic murmurs is essential. In the cardiac assessment of children, the ability to clearly characterize the S2 is perhaps more crucial than any other sound, and the effects of respiration are important in both normal and abnormal cardiac assessment. The components of the S2 in childhood are normally split with inspiration and are single on expiration. A loud pulmonary closure sound suggests the possibility of pulmonary artery hypertension. The S2 may be widely split or fixed in association with right ventricular volume overload or delayed right ventricular conduction. Normal inspiratory splitting of the S2 should be sought and established in all patients but may be difficult in some cases. In infants with rapid respiratory rates, the presence of splitting at any time during the respiratory cycle may be accepted as normal. An ejection click or sharp sound present at the left upper sternal border, louder with expiration or heard only on expiration, is characteristic of pulmonary valve stenosis. The ejection click follows the period of isovolumic contraction and occurs as a consequence of restricted semilunar (aortic or pulmonary) valve excursion at the onset of ventricular ejection. When the ejection sound occurs at the right upper sternal border or at the apex, a bicuspid or stenotic

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aortic valve is suggested. In contrast to ejection clicks, right-sided cardiac murmurs are accentuated with inspiration. Left heart auscultatory abnormalities vary little with the respiratory cycle. INNOCENT MURMURS OF CHILDHOOD

Normal murmurs of childhood are comprised of six systolic and two continuous types: Systolic murmurs Vibratory Still's murmur Pulmonary flow murmur Peripheral pulmonary arterial stenosis murmur Supraclavicular systolic murmur Aortic systolic murmur Continuous murmurs Venous hum Mammary arterial souffle Normal murmurs are never solely diastolic. The intensity or loudness of the murmur is grade 3 or less and consequently is never associated with a palpable thrill. The majority of all murmurs, both innocent and organic, are accentuated by fever, anemia, or increased cardiac output. Systolic Murmurs Vibratory Still's Murmur

The most common innocent murmur in children is the vibratory systolic murmur described by StiW in 1909, frequently retaining the eponym "Still's murmur." The murmur is most typically audible between ages 2 and 6 years but may be present as late as adolescence or as early as infancy. The murmur is low to medium in pitch, confined to early systole, generally grade 2 (range, 1-3), and maximal at the lower left sternal edge and extending to the apex. The murmur is generally loudest in the supine position and often changes in character, pitch, and intensity with upright positioning. The most characteristic feature of the murmur is its vibratory quality, initially described by Still as "a twanging sound, very much like that made by twanging a piece of tense string."41This vibratory quality is attributable to the presence of harmonic overtones or multiples of the baseline sound frequency (70-150 cycles/sec), giving a pleasing or musical character to the murmur. The quality of the murmur can thus never be described as "noisy" or "rough." Quite characteristically, the intensity of the murmur diminishes and the pitch changes with upright positioning but seldom disappears. The origin of the murmur remains obscure. Its origins have been ascribed to vibration of the pulmonary valves during systolic ejection,23vibrations arising from the shift in blood mass in the dynamically contracting ventricle,'8 physiologic narrowing of the left ventricular outflow and most likely attributable to the presence of ventricular false tendons.3I Phonocardiographic recordings have shown innocent murmurs to arise from either the right v e n t r i c ~ l a or r~~ left ventricularm outflow tracts. The prevalence of false tendons remains high in adults (16.8%)and was more frequently associated with innocent systolic ejection

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murmurs,22although the typical vibratory quality of the Still's murmur is seldom appreciated beyond adolescence. Pulmonary Flow Murmur

An innocent pulmonary outflow tract murmur may be heard in children, adolescents, and young adults. The murmur is a crescendo-decrescendo, early to mid-peaking ejection systolic murmur that is confined to the second and third interspace at the left sternal border. It is of low intensity (grade 2-3) and transmits to the pulmonary area. It is rough and dissonant without the vibratory musical quality of the Still's murmur. The murmur is best heard in the supine position and is exaggerated by the presence of a pectus excavatum; a straight back, or kyphoscoliosis, which results in compression or approximation of the right ventricular outflow tract to the chest wall. The murmur is augmented in full exhalation while the patient is supine, rarely resulting in the perception of a palpable thrill, and is diminished by upright positioning and held inspiration. The murmur of an atrial septa1 defect is attributable to increased flow through the pulmonary outflow tract and may be indistinguishable from the innocent pulmonary flow murmur; however, the hyperdynamic right ventricular impulse, wide splitting of the pulmonary component of the 52, and the presence of a mid-diastolic flow rumble should enable distinction. The murmur of pulmonary valve stenosis may be distinguished from the innocent pulmonary flow murmur by the frequent presence of a systolic thrill, higher pitch, longer duration, or presence of an ejection click. The presence of an ejection click signifies the improper opening of a semilunar valve and is always of pathologic origin. In patients with pulmonary stenosis the S2 may be widely split, and the P2, when audible, is of diminished intensity. Peripheral Pulmonary Arterial Stenosis Murmur

A common murmur heard frequently in newborns and infants fewer than 1 year of age is the audible turbulence of peripheral branch pulmonary arterial stenosis, angulation, or narrowing. These ejection character murmurs are typically grade 1 or 2, low to moderately pitched, beginning in early to midsystole, and extending up to and occasionally just beyond the S2. These murmurs are most often present in normal newborns but may be associated with viral lower RTIs and reactive airway disease in older infants. In fetuses, the pulmonary trunk is a relatively dilated, domed structure because it receives the majority of combined cardiac output from the high-pressure right ventricle. Right and left pulmonary artery branches arise from this major trunk as comparatively small lateral branches that receive little intrauterine flow because the lungs are relatively collapsed. When the lungs expand at birth, the relative disparity transiently persists. In addition, the branches arise at comparatively sharp angles from the main pulmonary trunk, accounting for turbulence and a recognized physiologic drop in pressure from the main to the proximal branch pulmonary arteries? In older infants, in association with an RTI, regional vascular reactivity and pulmonary blood flow redistribution may account for the reappearance of the murmur beyond the neonatal period. Characteristically, the murmurs are often best heard peripherally in the axillae and back, with both regional and temporal variability. Because of the rapid respiratory rate of infants, similar sound frequency composition of breath sounds and peripheral location of the murmurs, these murmurs are often missed or overlooked. For reasons that are unclear, they are often most evident in the

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recovery phase of a respiratory illness. Importantly, the murmur of peripheral branch stenosis changes with heart rate variability, increasing in intensity, with heart rate slowing as the stroke volume increases and conversely diminishing with tachycardia and reduction in stroke volume. The normal peripheral branch stenosis murmur may be indistinguishable from the peripheral murmur of significant stenosis of the branch pulmonary vessels seen in the Williams or rubella syndromes or accompanying hypoplasia or narrowing of the pulmonary arteries. Murmurs of significant anatomic narrowing may be distinguished by their higher pitch and extension beyond the S2 and occur in children beyond the first few months of life. The pulmonary flow murmur of an atrial septa1 defect may mimic this murmur but characteristically is not seen in this age group. Proximal pulmonary valve or right ventricular outflow obstruction may also closely resemble this murmur but is often of louder intensity, possibly associated with an ejection click and heard maximally lower along the left sternal border. Supraclavicular or Brachiocephalic Systolic Murmur

A supraclavicular systolic crescendo-decrescendo murmur may be heard in children and young adults.39This systolic murmur is audible maximally above the clavicles and radiates to the neck but may present to a lesser degree on the superior chest. The murmur is low to medium in pitch, of abrupt onset, brief, and maximal in the first half or two thirds of systole. High pitch or extension into diastole is unusual and suggests significant vascular obstruction. The murmur is present with the patient supine and sitting but varies with hyperextension of the s h o ~ l d e r s The . ~ ~ shoulders can be hyperextended, with the elbows brought behind the back until the shoulder girdle is taut. When this maneuver is done rapidly, the murmur diminishes or disappears a l t ~ g e t h e r . ~ ~ Supraclavicular systolic murmurs are thought to arise from the major brachiocephalic vessels as they arise from the aorta.20 Aortic Systolic Murmur

Innocent systolic flow murmurs may arise from the outflow tract in older children and adults. The murmurs are ejection in character, confined to systole and audible maximally in the aortic area. In children, these murmurs may arise secondarily to extreme anxiety, anemia, hyperthyroidism, fever, or any other condition of increased systemic cardiac output. In trained athletes, slower heart rates with increased stroke volume may give rise to short crescendo-decrescendo murmurs of low to medium pitch. Physical examination may suggest a relatively displaced thrusting apex and physiologic S3.Ib These murmurs must be distinguished from the systolic murmur of hypertrophic cardiomyopathy and additional fixed obstructions of the left ventricular outflow tract. The presence of a family history for hypertrophic cardiomyopathy, history of unexplained death in a young individual, particularly if associated with activity, is justification for referral. A systolic murmur that gets louder with performance of the Valsalva maneuver is considered almost diagnostic of hypertrophic cardiomyopathy with systolic anterior motion of the mitral valve. A reduction in venous return results in closer apposition of the septum and mitral valve and dynamic narrowing of the left ventricular outflow tract. By contrast, rapid squatting improves venous return; the left ventricular chamber size is enlarged, the mitral valve and septum are farther apart, and the murmur

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of hypertrophic cardiomyopathy gets softer.= The cause of this type of murmur is often difficult to determine, and often referral and further investigations may be indicated.

Normal Continuous Murmurs Venous Hum

The most common type of continuous murmur heard in children is the innocent cervical venous hum. First described by Potah%in 1867, this continuous murmur is most audible on the low anterior part of the neck just lateral to the sternocleidomastoid muscle but often extends to the infraclavicular area of the anterior chest wall. The murmur is generally louder on the right than on the left, louder with the patient sitting than lying, and is accentuated in diastole. Intensity varies from faint to grade 6, and occasionally patients are aware of a loud hum.5 The murmur is quite variable in character, often described as whining, roaring, or whirring. The venous hum is best accentuated or elicited with the patient in a sitting position and looking away from the examiner. The murmur often resolves or changes in character with lying down and may be eliminated or diminished by gentle compression of the jugular vein or turning the patient’s head toward the side of the murmur. The murmur is thought to arise from turbulence at the confluence of flow as the internal jugular and subclavian veins enter the superior vena cava or perhaps from angulation of the internal jugular vein as it courses over the transverse process of the atlas.s Mammary Arterial Souffle

The mammary souffle was first described by van den Bergh in 190879aand occurs most commonly late in pregnancy and in lactating women but rarely occurs in adolescence. The murmur arises in systole but may extend well into diastole, being audible maximally on the anterior chest wall over the breast. A distinct gap is usually present between the S1 and the origin of the murmur, thought to relate to the delayed arrival of cardiac stroke volume at the peripheral vasculature. The murmur is generally high pitched and has an unusual superficial character but may vary considerably from day to day. The murmur is thought to be arterial in origin, arising from the plethoric vessels of the chest wa11j2 The murmur must be distinguished from the continuous high-pitched murmur of an arteriovenous fistula or a patent ductus arteriosus; however, characteristically, the mammary souffle varies significantly from day to day, presents in a most distinctive patient population (described earlier), and resolves with termination of lactation.

SUMMARY

In conclusion, the evaluation of cardiac murmurs represents one of the most skilled and demanding aspects of the pediatric physical assessment. It does provide a significant service to patients and a level of satisfaction for competent practitioners, and referral is not always warranted. The decision for referral is based on the presumed diagnosis, confidence of the examiner, and level of

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parental anxiety. Most often, referral to a cardiologist for directed investigation rather than direct echocardiographic assessment serves patients best.

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Address reprint requests to Andrew N. Pelech, MD Division of Pediatric Cardiology The Medical College of Wisconsin 8701 Watertown Plank Road PO Box 26509 Milwaukee, WI 53226-0509