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Cardiac Disease in Pregnancy
Medical Problems in Pregnancy
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Cardiac Disease in Pregnancy John C. Cianopoulos, MD*
The approach to the patient with cardiovascular disease antedating pregnancy (or developing during pregnancy) must be undertaken with knowledge of the underlying physiologic alterations of pregnancy. The cardiovascular system undergoes numerous physiologic alterations that may place the patient with cardiac disease at risk.
PHYSIOLOGIC CARDIOVASCULAR ALTERATIONS OF PREGNANCY Cardiac Output One of the most significant changes in cardiovascular physiology in pregnancy is the increase in cardiac output. Cardiac output begins to rise in the first trimester and continues a steady increase to peak at 30 to 50 per cent of pre-existing levels, at 32 weeks' gestation. 2.20 This rise in output is affected by both increases in heart rate and stroke volume. There is a rise in endogenous circulating catecholamines (which produce a positive inotropic) as well as a positive chronotropic, myocardial response. 2.3,38,72 Left end-diastolic volume increases by an expanding plasma volume leading to an increased myocardial con tractility, also serving to increase stroke volume.
Plasma Volume Plasma volume increases by 40 to 50 per cent of pre-existing levels 54 ; this increase in plasma volume is at a greater magnitude than red cell mass (which increases by 20 to 30 per cent), producing a dilutional "physiologic" anemia of pregnancy. 12
Systemic Vascular Resistance The placental bed serves as a large arterio-venous shunt that produces a lowered systemic vascular resistance. There is physiologic vasodilatation
*Assistant
Professor, Division of Maternal-Fetal Medicine, Department of Obstetrics and Gynecology, Loyola University Medical Center, Maywood, Illinois
Medical Clinics of North America-Vo!' 73, No. 3, May 1989
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in the arteriolar vascular bed due to hormonal influences (believed to be secondary to endothelial prostacyclin and circulating progesterone). Mean arterial pressure in normal pregnancy is slightly reduced during a cardiac cycle, secondary to arteriolar vasodilation. 6.14 Blood Flow The changes in cardiac output and systemic vascular resistance lead to an increased blood flow to the renal vascular bed, the uterus, the breasts, and the skin. The most dramatic increase in flow occurs in the uterine artery with a peak flow of 500 to 600 ml per minute at term.24 Pulmonary Circulation Similar alterations occur in the pulmonary circulation as are seen in the systemic circulation. There is vasodilatation with an increased volume of capacitance. 23 However, the volume and the capacitanic changes almost equal each other, leading to virtually no change in mean pulmonary artery pressures and wedge pressures remain in the normal range (4.5 to 6.5 mm Hg).6 The reserve of the pulmonary circulation for increased volume is reduced. The pregnant patient is, therefore, at greater risk for the development of pulmonary edema in a variety of stressing conditions. COUNSELING THE PREGNANT PATIENT WITH CARDIAC DISEASE Due to the physiologic alterations of pregnancy, the patient with preexisting cardiovascular disease is at risk during pregnancy. The risk of perinatal mortality, maternal morbidity, and maternal mortality are dependent upon three factors: (1) the underlying cardiac lesion; (2) the functional derangement produced by the lesion; and (3) development of pregnancy-related complications-that is, pregnancy-induced hypertension, hemorrhage, and infection. The risks of maternal morbidity or mortality are dependent upon the underlying cardiac lesion. Patients with uncomplicated septal defects, tricuspid disease, or corrected aortic coarctation have less than a 1 per cent maternal mortality.32.58 Patients with conditions leading to hemodynamically Significant pulmonary hypertension have as much as a 50 per cent chance of mortality and a 60 to 70 per cent chance of significant functional morbidity during pregnancy. Clar~2,58 has recently classified the risk of mortality associated with specific cardiac lesions (Table 1). The potential for a successful outcome of pregnancy is also determined by the functional derangement with which the patient enters pregnancy. Those patients entering pregnancy with New York Heart Association (NYHA) functional class I or 11 (Table 2) lesions usually do well during pregnancy. Patients entering pregnancy with NYHA functional class III and IV lesions have a 30 to 50 per cent chance of Significant hemodynamic morbidity, and a 25 to 50 per cent chance of maternal mortality.6,58 These patients should be advised against becoming pregnant. As pregnancy progresses, specific pregnancy-related complications may
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Table 1.
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Risk of Mortality Associated with Specific Cardiac Lesions Low Risk of Maternal Mortality (less than 1%) Septal defects New York Heart Association classes I and Il Patent ductus arteriosus Pulmonic/tricuspid lesions Moderate Risk of Maternal Mortality (5-15%) NYHA classes III and IV mitral stenosis Aortic stenosis Marfan's syndrome with normal aorta Uncomplicated co-arctation of the aorta Past history of myocardial infarction High Risk of Maternal Mortality (25-50%) Eisenmenger's syndrome Pulmonary hypertension Marfan's syndrome with abnormal aortic root Periportal cardiomyopathy
Adapted from Clark SL: Labor and delivery in the pregnant patient with structural cardiac disease, Clin Perinatol 13:697, 1986.
occur that may produce significant hemodynamic changes. The development of pre-eclampsia, vaginal hemorrhage, or infections are examples of conditions that stress the cardiovascular system and thus may alter the patient's functional compensation, The patient with pre-existing cardiac disease must be carefully observed throughout the pregnancy to assure such complications do not develop, The patient with cardiac disease must also be assessed individually and counseled as to the risks she and her fetus will undertake during pregnancy, Patients with lesions amenable to surgical correction are best served by undergoing surgical correction prior to pregnancy. Patients with congenital heart disease must be advised as to the risks of their offspring inheriting a congenital lesion, The majority of these lesions Table 2.
NYHA Functional Classification of Cardiac Disease
Class I No functional limitation of activity No symptoms of cardiac decompensation with activity Class Il Mild amount of functional limitation Patients are asymptomatic at rest Ordinary physical activity results in symptoms Class III Limitation of most physical activity Asymptomatic at rest Minimal physical activity results in symptoms Class IV Severe limitation of physical activity Patients may be symptomatic at rest Any physical activity results in cardiac symptoms Adapted from The Criteria Committee of the New York Heart Association Nomenclature and Criteria for Diagnosis of Diseases of the Heart and Great Vessels, ed 8. New York, New York Heart Association, 1979; with permission.
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follow a polygenic/multifactorial mode of inheritance with a 2 to 5 per cent risk of recurrence. (A few important exceptions are Marfan's syndrome and idiopathic hypertrophic subaortic stenosis that follow an autosomal dominant mode of inheritance.) SPECIFIC CARDIAC LESIONS Aortic Stenosis Patients with mild to moderate degrees of aortic stenosis tolerate pregnancy well. The major functional problem associated with this lesion is the maintenance of adequate cardiac output. Most patients experience an improved cardiac output with the plasma volume increases of pregnancy. Patients with severe disease (aortic gradients of greater than 100 mm Hg) are at significant risk in pregnancy; the reported mortality in these patients is 17 per cent. 5 Significant decreases in preload will lead to a fall in cardiac output and, potentially, myocardial ischemia, cerebral ischemia, and sudden death. Hypovolemia and hypotension must be avoided in these patients. Spinal anesthetic agents are contraindicated, because the resultant sympathetic block may produc~ hypotension. The greatest risk to these patients is during delivery or termination of pregnancy. 5 A 40 per cent maternal mortality has been reported with voluntary interruption of pregnancy in the early second trimester. Labor and delivery in these patients is best managed with invasive cardiac monitoring. Adequate preload must be maintained and hypotension avoided. Pulmonary capillary wedge pressures are best maintained at a slightly higher level to serve as a preload reserve against potential blood loss during delivery. 12 These patients require bacterial endocarditis prophylaxis. It is advisable that patients with hemodynamically significant degrees of aortic stenosis undergo corrective surgery (either valvuloplasty or valve replacement) prior to becoming pregnant. Aortic Insufficiency Aortic insufficiency is well tolerated by the pregnant patient. This lesion, however, is often associated with mitral valvular lesions as a result of rheumatic fever. If a patient demonstrates signs of pulmonary congestion, therapy should be directed at physical activity restriction and volume reduction. Digitalis and diuretics are sometimes required in the management of these patients. Mitral Stenosis Mitral stenosis is most often rheumatic in origin. This lesion may become life-threatening during pregnancy, as left atrial outflow obstruction leads to decreased left ventricular diastolic filling resulting in a fixed cardiac output. With increased pulmonary vascular volume in pregnancy, pulmonary congestion and pulmonary edema may result. With large increases in left atrial volume, atrial arrhythmias (atrial flutter/fibrillation) are seen. Stagnant blood within the distended left atrium may lead to thrombus formation and systemic arterial emboli. Patients with atrial fibrillation may benefit from hep-
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arin anticoagulation. Functional decompensation during pregnancy is treated wtih fluid restriction, digitalis, and possibly diuretic therapy. Labor, delivery, and the immediate postpartum period provide the most critical stress for these patients. The 300 to 500 ml autotransfusion from the utero-placental circulation that occurs at the time of delivery may produce acute pulmonary edema. Those patients with NYHA classes III and IV disease should be monitored with invasive pulmonary artery catheterization; fluid status should also be closely followed. It is important to remember that, in patients with mitral stenosis, pulmonary capillary wedge pressure is not an adequate estimate ofleft ventricular diastolic filling pressure. Monitoring of cardiac output is indicated to assess left ventricular function, especially if volume reduction with diuretics is undertaken. 15,16 The ideal mode of delivery is vaginal with regional anesthesia (epidural) for pain reduction in the first and second stage of labor. Tachycardia must be avoided as left ventricular end-diastolic volume may become reduced. In the past, elective mid-forceps operations (with a shortened second stage of labor) have been advocated. With close hemodynamic monitoring, these potentially harmful operations may be avoided, and these patients may be allowed to valsalva during the second stage of labor to help effect fetal expulsion. In hemodynamically severe forms of mitral stenosis, mitral commissurotomy or valve replacement may be undertaken during pregnancy.17 Recently, a successful percutaneous balloon valvuloplasty has been performed at our institution in a pregnant patient with hemodynamically significant mitral stenosis at 34 weeks' gestation. 25 This new technology may prove beneficial in the management of pregnant patients with severe disease. These procedures may reduce the need for invasive thoracic procedures during pregnancy. Mitral Insufficiency Patients with mitral regurgitation do well in pregnancy. Unlike mitral stenosis, rheumatic etiologies are rare. Echocardiography is often helpful in identifying the underlying etiology.ll Mitral valve prolapse (that occurs in approximately 10 per cent of pregnancies) is a well-tolerated, benign form of mitral insufficiency. Therapeutic interventions are rarely necessary. .56 Patients who have vegetative endocarditis as the underlying etiology of their valvular lesion require prolonged antibiotic prophylaxis throughout pregnancy with penicillin or erythromycin, as endocarditis is a common complication. Congenital Heart Disease Congenital cardiac disease is becoming the most common cardiac problem encountered in the perinatal patient. This is probably because corrective surgical procedures have allowed these patients to reach child-bearing age. It is important to recognize the genetic nature of these lesions and that children of affected individuals are at risk for having similar cardiac lesions, as well as other congenital malformations. 4 S,49 In utero echocardiography may be beneficial in the antenatal diagnosis of these conditions. Genetic counseling is required because of the possibility of transmission of these cardiac defects to the offspring.
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LEFT-TO-RIGHT SHUNTS Ventricular Septal Defect (VS D) Most patients with VSDs are diagnosed in childhood with a loud systolic murmur characteristic of this lesion. The majority of these patients undergo corrective surgery prior to reaching the child-bearing ages. Patients with uncorrected lesions, in the absence of pulmonary hypertension, do well in pregnancy. Care in management to avoid fluid overload is needed. Most VSD lesions are inherited via the polygenic/multifactorial route; the risk of fetal congenital lesion is 3 to 5 per cent. Finally, prophylaxis for bacterial endocarditis is needed at the time of delivery. Atrial Septal Defects (ASD) Atrial septal defects of the ostium secundum are one of the most common congenital cardiac lesions found in women of child-bearing age. 49 Pregnancy is well tolerated in these patients. The risk of developing bacterial endocarditis with ASD is low, and antibiotic prophylaxis at the time of delivery is not warranted. There is a 2 to 3 per cent chance of fetal congenital heart disease in patients with this cardiac lesion. 49 Patent Ductus Arteriosus Those patients with patent ductus arteriosus tolerate the hemodynamic stress of pregnancy well. When pulmonary hypertension is associated with this lesion, however, the patient is at significant risk (see pulmonary hypertension). Bacterial seeding is common in these patients and antibiotic prophylaxis is necessary during delivery. The risk of fetal congenital heart disease is 3 to 4 per cent. 49 RIGHT-TO-LEFT SHUNTS Coarctation of the Aorta Patients with surgically corrected aortic coarctation withstand the stress of pregnancy with little difficulty. 18.27 Those rare patients who enter pregnancy with an uncorrected lesion are at risk for aortic dissection, cerebral hemorrhage, and end-organ hypertensive complications. The risk of cerebral hemorrhage is noted in those individuals with associated cerebral vascular aneurysms. The risk of maternal mortality is 3 to 6 per cent. 18 Occasionally, a bicuspid aortic valve is correlated with aortic coarctation. These patients have the highest risk during pregnancy. 57 The risk of associated fetal congenital heart lesion is 2 per cent. 49 Tetralogy of Fallot Tetralogy of Fallot is the most common right-to-Ieft shunt found in women of child-bearing age. 1S . 4S The lesion is composed of the tetrad of pulmonic valvular stenosis, right ventricular hypertrophy, an overriding aorta, and a ventricular septal defect. Pregnant patients with tetralogy of Fallot have a risk of increased shunting as systemic vascular resistance decreases. Patients who have high hematocrit, greater than 65 per cent, syn-
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copal episodes, a Pa0 2 less than 70 mm Hg, and high right heart pressures have a poor prognosis in pregnancy.1S Venous return and right-sided enddiastolic volume are critical in maintaining adequate hemodynamic function in these patients. The times of most physiologic stress to these patients are during labor, delivery, and the immediate postpartum period. Blood loss with postpartum hemorrhage is particularly dangerous, as venous return is impaired. 3 .5 ,4,5 Surgically corrected patients with normal oxygen saturation are able to successfully complete pregnancy with minimal risks. The fetal risk of congenital heart disease is 4 per cent.48 Eisenmenger's Syndrome Patients with high pulmonary vascular resistance due to intracardiac shunting (Eisenmenger's syndrome) are unable to withstand the hemodynamic stress of pregnancy. Sudden death due to hypoxemia (secondary to impaired pulmonary perfusion) can occur ante-, intra-, or postpartum. The published maternal mortality with this lesion is 50 to 70 per cent. 26,47 Patients with Eisenmenger's syndrome should be advised not to become pregnant. Voluntary termination of pregnancy may be considered in these patients because of an extremely high maternal, as well as perinatal, mortality rate. 26,47 Patients who maintain pregnancy require anticoagulation and endocarditis antibiotic prophylaxis during delivery, 53 Gleicher et al26 have reported a 34 per cent maternal mortality with vaginal delivery and a 75 per cent maternal mortality associated with cesarean section. This observation is due to an increased blood loss and decreased venous return, in patients undergoing cesarean section, Pulmonary Hypertension Patients with hemodynamically significant pulmonary hypertension, regardless of etiology, should be advised not to become pregnant. These patients have as much as a 50 per cent risk of maternal mortality and a 40 to 50 per cent risk of perinatal mortality. 32,41 As with Eisenmenger's syndrome, voluntary termination of pregnancy may be considered. First trimester terminations with dilatation and curettage are well tolerated. Patients in the second trimester have a greater risk associated witb the termination procedure; the procedure of choice is dilatation and evacuation, Abortifacients, such as prostaglandins and hypertonic saline, are contraindicated. 41 Patients with pulmonary hypertension must be carefully monitored during lab or. Blood loss and hypotension should be avoided and invasive pulmonary artery catheterization is indicated, Pulmonary capillary wedge pressures are best maintained at elevated levels to insure adequate left ventricular preload. 17 Regional anesthetics should be used with caution since sympathetic blockage with vasodilation will reduce venous return. Recent reports have advocated an anesthetic technique utilizing epidural narcotic agents (such as morphine or fentanyl) that do not effect peripheral vasodilatation, I This may be the anesthetic of choice in these patients. As with Eisenmenger's syndrome, the vaginal route of delivery is safer and is preferred over cesarean section.
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Peripartum Cardiomyopathy Patients with peripartum cardiomyopathy present with sudden onset of congestive heart failure with a history of no previous cardiac disease in the last 4 weeks of pregnancy or the first 6 months postpartum. The etiology of this condition remains unknown. The diagnosis is established by demonstrating decreased cardiac output due to impaired left ventricular function. 19 These patients require investigation for other conditions leading to dilated congestive cardiomyopathy-that is, viral cardiomyopathy, ischemic heart disease, and amyloidosis. A characteristic histologic picture is observed on myocardial biopsy.36.42 The "classic" patient is in her mid-30s, black, multiparous, with a multiple gestation; this condition, however, has been observed in many varied patients. The diagnosis is primarily one of exclusion; only after all other causes of sudden congestive failure have been ruled out can the diagnosis of peripartum cardiomyopathy be assigned. These patients are best managed with sodium and fluid restriction, decreased physical activity, positive inotropic agents (digitalis), and diuretic therapy. Over 60 per cent of patients will recover and return to normal cardiac function. If the symptoms persist for 6 months beyond delivery, the prognosis is poor,42.71 and cardiac transplantation may become necessary. Patients with periportal cardiomyopathy should be advised that there is a 50 to 60 per cent recurrence risk and that future pregnancy is not advisable. Coronary Artery Disease Pregnant patients with ischemic heart disease are uncommon since coronary artery disease is rare in women of child-bearing age. In a review of 68 cases of myocardial infarction during pregnancy, Hankins et apo reported that only nine patients (13 per cent) had known coronary artery disease antedating their pregnancy. The majority of patients who suffer ischemic heart disease during pregnancy will have their first manifestation of their disease during pregnancy. The hemodynamic demands of pregnancy upon the myocardium may serve as a stress to the coronary circulation producing ischemia in patients with previously asymptomatic disease. The overall mortality in these patients is 35 per cent with patients who present with ischemia in the third trimester having the highest mortality, 45 per cent.30 Management consists of oxygen, vasodilator therapy, and pain relief. The stress of labor is best avoided, and elective induction within 2 weeks of infarction is contraindicated. Delivery is managed with conduction anesthesia and a shortened second stage, with elective forceps delivery being indicated to minimize myocardial demands during the process of delivery. 31 Cardiac Arrhythmias Patients with cardiac dysrhythmias that antedate pregnancy are able to tolerate pregnancy. The major concern with these patients is the alteration of their cardiotoxic drugs for both fetal and maternal indications. Digitalis, procainamide, and quinidine have not been shown to be teratogenic or harmful to the fetus and thus may be used. 59 Beta-blockers also may be used, although there is a risk of transient neonatal hypoglycemia and hypotonia. Controversy exists whether beta-blockers are implicated in impaired fetal
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growth. Recent data suggest that the underlying disease state, and not the beta-blockers, are the etiology of the correlation between these drugs and intrauterine growth retardation. 67 When indicated, calcium channel blockers may be used in pregnancy. There have been isolated case reports implicating these agents with sudden intrauterine fetal death. Other recent reports have indicated that oral antiarrhythmic agents with action against ventricular ectopy, such as flecainide and mexiletine, may be used in pregnant patients with recurrent ventricular tachyarrhythmias. 28 Although no adverse fetal complications have been reported to date, these agents must be used with caution because the number of patients exposed to these drugs in pregnancy remains small. Patients with supraventricular tachyarrhythmias resistant to medical therapy may undergo Die cardioversion during pregnancy, as the risk to the fetus with low to moderate energy settings appears small. 62 Prosthetic Heart Valves (Anticoagulation) Patients who have undergone corrective surgery for valvular heart disease who have regained normal cardiac hemodynamic function usually tolerate pregnancy well, although their pregnancies remain at higher risk. 4.10.11.50 Patients with mechanical prosthetic valves require full anticoagulation and bacterial endocarditis prophylaxis during pregnancy. As there is a physiologic increase in coagulation factors during pregnancy, these patients are at greater risk for valvular thrombosis and sudden death. 37.51.61 Anticoagulation with warfarin and its derivatives are contraindicated during pregnancy since these agents readily cross the placenta and are teratogenic to the fetus. First trimester exposure to warfarin has been associated with the condition termed warfarin embryopathy. 8.13.29.64 This syndrome includes mid-face hypoplasia, mental retardation, optic atrophy, blindness, and chondrodysplasia punctata (stippled epiphyses).63,64,74 Previously, second and early trimester warfarin use had been advocated, but recent data suggest that warfarin use during pregnancy may cause central nervous system abnormalities (believed secondary to intrauterine intracranial bleeding). It is therefore recommended that warfarin be avoided throughout pregnancy. The anticoagulant of choice is heparin. Due to its molecular structure, heparin does not cross the lipoprotein membranes of the placenta and is associated with no adverse fetal effects. Adverse maternal side effects associated with prolonged heparin administration in pregnancy have been reported. These include reversible bone demineralization, thrombocytopenia, hyperkalemia, and adverse dermatologic reactions I4 ,21,33; these reactions, fortunately, are uncommon. The subcutaneous route of administration will allow for outpatient management. Heparin may be administered as two to three subcutaneous boluses of 10,000 to 20,000 units to maintain the activated partial thromboplastin time (aPPT) 1. 5 to 2 times above normal. 46 As subcutaneous absorption may lead to wide fluctuations in the coagulation times, an alternative method of continuous subcutaneous heparin administration via an infusion pump has been shown to be useful. 46 Patients may resume warfarin therapy in the postpartum period since only small amounts of warfarin have been shown to be excreted in breast milk. These patients may breast-feed their infants if they wish. 74 However, it is essential to observe these patients
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Table 3. American Heart Association Recommendations for Bacterial Endocarditis Prophylaxis at the Time of Deli1Jery Ampicillin, 2 g, IV Gentamicin, 1.5 mg/kg, IV/I~l In Penicillin-allergic Patients: Vancomycin, 1 g, IV Gentamicin, 1.5 mg/kg, IV/I M To be administered in three doses every 8 hours
carefully, as there is a risk of valvular thrombosis and sudden death if their anticoagulation becomes subtherapeutic. LABOR AND DELIVERY MANAGEMENT
The management oflabor and delivery in the patient with cardiac disease is dictated by the functional status of the patient. Those patients with NYHA functional classes I and 11 may be allowed to labor and deliver with minimal intervention. Close observation of intake, output, and cardiac rate and rhythm are important. Pain relief with conduction regional anesthetic is indicated to prevent tachycardiac responses. Postpartum hemorrhage and excessive blood loss should be avoided. Invasive cardiac monitoring may be used on an individual basis when indicated, although it is not commonly needed in these patients. Patients with NYHA functional classes III or IV, or patients with hemodynamically significant pulmonary hypertension, are at higher risk during labor and delivery. The optimal route of delivery is a controlled vaginal delivery with very close observation of fluid status. As volume shifts and blood losses are greater for cesarean section, these procedures should be performed only for the usual fetal or obstetrical indications. The preload, afterload, and myocardial work must be carefully observed. Invasive monitoring with pulmonary artery catheters and radial artery catheters are often indicated to maintain close hemodynamic observation of these patients. Pain relief is essential and regional anesthetics may be used; epidural narcotic anesthesia may be useful during labor. I When indicated, bacterial endocarditis prophylaxis should be administered following the delivery of the fetus (Table 3). CONCLUSION
With a thorough understanding of the hemodynamic alterations of pregnancy and the pathophysiology of cardiac disease, the clinician can best serve patients with cardiac disease. Prior to undertaking pregnancy, patients with cardiac disease require complete investigation and counseling regarding the risks they shall undertake in pregnancy. Investigative procedures, drug therapy, and invasive maternal procedures may become necessary during pregnancy. It is important to understand both the maternal and fetal risks associated with these procedures. Labor, delivery, and the immediate
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postpartum period are times of particular stress in a number of cardiac lesions. Techniques of invasive hemodynamic monitoring have improved the prognosis and management of patients with significant cardiac lesions in pregnancy.
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59. Rotmensch HH, Elkayam U, Frishman \V: Antiarrhythmic therapy during pregnancy. Ann Intern Med 98:487-497, 1983 60. Hubin PC: Beta-blockers in pregnancy. N Engl J ~led 305:1323-1326, 19tH 61. Salazar EL, Zajarias A, Cutierrez N, et al: The prohlem of cardiac valve prostheses, anticoagulants, and pregnancy. Circulation 70(suppl 1):1-169-1-177, 1984 62. Schroeder JS, Harrison DC: Repeated cardioversion during pregnancy: Treatment of refractory paroxysmal atrial tachycardia during three successive pregnancies. Am J Cardiol 27:445, 1971 63. Shaul WL, Emery H, Hall JC: Chondrodysplasia punctata: Maternal warfarin use during pregnancy. Am J Dis Child 129:360-362, 1975 64. Sherman S, Hall BD: Warfarin and fetal abnormalitv. Lancet 1:692, 1976 65. Shulman ST, Amren DP, Bisno AL, et al: Prevention' ofhacterial endocarditis: A statement for health professionals hy the Committee on Hheumatic Fever and Infective Endocarditis of the Conncil on Cardiovascular Disease in the Young. Circulation 70: 1123A-1127A, 1984 66. Spearing C, Fraser I, Turner C, et al: Long-term self administered subcutaneous heparin in pregnancy. Br Med J 1:1457, 1978 67. Stevenson RE, Burton ~1, Ferlanto CJ, et al: Hazards of oral anticoagulants during pregnancy. JAM A 243:1549, 1980 68. The Criteria Committee of the New York Heart Association: Nomenclature and Criteria for Diagnosis of Diseases of the Heart and Creat Vessels, ed 8. New York, New York Heart Association, 1979 69. Ue!and K, Novy M], Metcalfe J: Hemodynamic responses of patients with heart disease to pregnancy and exercise. Am J Obstet Cynecol 113:47, 1972 70. Ueland K, Novy M, Peters on EN, et al: Maternal cardiovascular dynamics. Am J Obstet Cynecol 104:856-864, 1969 71. Veille JC: Peripartum cardiomyopathies: A review. Am J Obstet Cynecol 148:805-818, 1984 72. Waiters WAW, MacCregor WC, Hills M: Cardiac output at rest during pregnancy and the puerperium. Clin Sci 30:1-11, 1966 73. Wang RYC, Lee PK, Chow JSF, et al: Efficacy' of low-dose subcutaneously administered heparin in treatment of pregnant women with artificial heart valves. Med J Aust 2:126, 1983 74. Wessler S, Citel SN: Warfarin: From bedside to hench. N Engl J Med 311:645-652, 1984 75. Zimran A, Shilo S, Fisher D, et al: Histomorphometric evaluation of reversible heparininduced osteoporosis in pregnancy. Arch Intern ~lcd 146:386-388, 1986 Division of Maternal-Fetal ~ledicine Loyola University Medical Center 2160 S. First Avenue Maywood , IL 60153
002.5-712.5/89
$0.00 + .20
Cardiac Disease in Pregnancy John C. Cianopoulos, MD*
The approach to the patient with cardiovascular disease antedating pregnancy (or developing during pregnancy) must be undertaken with knowledge of the underlying physiologic alterations of pregnancy. The cardiovascular system undergoes numerous physiologic alterations that may place the patient with cardiac disease at risk.
PHYSIOLOGIC CARDIOVASCULAR ALTERATIONS OF PREGNANCY Cardiac Output One of the most significant changes in cardiovascular physiology in pregnancy is the increase in cardiac output. Cardiac output begins to rise in the first trimester and continues a steady increase to peak at 30 to 50 per cent of pre-existing levels, at 32 weeks' gestation. 2.20 This rise in output is affected by both increases in heart rate and stroke volume. There is a rise in endogenous circulating catecholamines (which produce a positive inotropic) as well as a positive chronotropic, myocardial response. 2.3,38,72 Left end-diastolic volume increases by an expanding plasma volume leading to an increased myocardial con tractility, also serving to increase stroke volume.
Plasma Volume Plasma volume increases by 40 to 50 per cent of pre-existing levels 54 ; this increase in plasma volume is at a greater magnitude than red cell mass (which increases by 20 to 30 per cent), producing a dilutional "physiologic" anemia of pregnancy. 12
Systemic Vascular Resistance The placental bed serves as a large arterio-venous shunt that produces a lowered systemic vascular resistance. There is physiologic vasodilatation
*Assistant
Professor, Division of Maternal-Fetal Medicine, Department of Obstetrics and Gynecology, Loyola University Medical Center, Maywood, Illinois
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in the arteriolar vascular bed due to hormonal influences (believed to be secondary to endothelial prostacyclin and circulating progesterone). Mean arterial pressure in normal pregnancy is slightly reduced during a cardiac cycle, secondary to arteriolar vasodilation. 6.14 Blood Flow The changes in cardiac output and systemic vascular resistance lead to an increased blood flow to the renal vascular bed, the uterus, the breasts, and the skin. The most dramatic increase in flow occurs in the uterine artery with a peak flow of 500 to 600 ml per minute at term.24 Pulmonary Circulation Similar alterations occur in the pulmonary circulation as are seen in the systemic circulation. There is vasodilatation with an increased volume of capacitance. 23 However, the volume and the capacitanic changes almost equal each other, leading to virtually no change in mean pulmonary artery pressures and wedge pressures remain in the normal range (4.5 to 6.5 mm Hg).6 The reserve of the pulmonary circulation for increased volume is reduced. The pregnant patient is, therefore, at greater risk for the development of pulmonary edema in a variety of stressing conditions. COUNSELING THE PREGNANT PATIENT WITH CARDIAC DISEASE Due to the physiologic alterations of pregnancy, the patient with preexisting cardiovascular disease is at risk during pregnancy. The risk of perinatal mortality, maternal morbidity, and maternal mortality are dependent upon three factors: (1) the underlying cardiac lesion; (2) the functional derangement produced by the lesion; and (3) development of pregnancy-related complications-that is, pregnancy-induced hypertension, hemorrhage, and infection. The risks of maternal morbidity or mortality are dependent upon the underlying cardiac lesion. Patients with uncomplicated septal defects, tricuspid disease, or corrected aortic coarctation have less than a 1 per cent maternal mortality.32.58 Patients with conditions leading to hemodynamically Significant pulmonary hypertension have as much as a 50 per cent chance of mortality and a 60 to 70 per cent chance of significant functional morbidity during pregnancy. Clar~2,58 has recently classified the risk of mortality associated with specific cardiac lesions (Table 1). The potential for a successful outcome of pregnancy is also determined by the functional derangement with which the patient enters pregnancy. Those patients entering pregnancy with New York Heart Association (NYHA) functional class I or 11 (Table 2) lesions usually do well during pregnancy. Patients entering pregnancy with NYHA functional class III and IV lesions have a 30 to 50 per cent chance of Significant hemodynamic morbidity, and a 25 to 50 per cent chance of maternal mortality.6,58 These patients should be advised against becoming pregnant. As pregnancy progresses, specific pregnancy-related complications may
CARDIAC DISEASE IN PREGNANCY
Table 1.
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Risk of Mortality Associated with Specific Cardiac Lesions Low Risk of Maternal Mortality (less than 1%) Septal defects New York Heart Association classes I and Il Patent ductus arteriosus Pulmonic/tricuspid lesions Moderate Risk of Maternal Mortality (5-15%) NYHA classes III and IV mitral stenosis Aortic stenosis Marfan's syndrome with normal aorta Uncomplicated co-arctation of the aorta Past history of myocardial infarction High Risk of Maternal Mortality (25-50%) Eisenmenger's syndrome Pulmonary hypertension Marfan's syndrome with abnormal aortic root Periportal cardiomyopathy
Adapted from Clark SL: Labor and delivery in the pregnant patient with structural cardiac disease, Clin Perinatol 13:697, 1986.
occur that may produce significant hemodynamic changes. The development of pre-eclampsia, vaginal hemorrhage, or infections are examples of conditions that stress the cardiovascular system and thus may alter the patient's functional compensation, The patient with pre-existing cardiac disease must be carefully observed throughout the pregnancy to assure such complications do not develop, The patient with cardiac disease must also be assessed individually and counseled as to the risks she and her fetus will undertake during pregnancy, Patients with lesions amenable to surgical correction are best served by undergoing surgical correction prior to pregnancy. Patients with congenital heart disease must be advised as to the risks of their offspring inheriting a congenital lesion, The majority of these lesions Table 2.
NYHA Functional Classification of Cardiac Disease
Class I No functional limitation of activity No symptoms of cardiac decompensation with activity Class Il Mild amount of functional limitation Patients are asymptomatic at rest Ordinary physical activity results in symptoms Class III Limitation of most physical activity Asymptomatic at rest Minimal physical activity results in symptoms Class IV Severe limitation of physical activity Patients may be symptomatic at rest Any physical activity results in cardiac symptoms Adapted from The Criteria Committee of the New York Heart Association Nomenclature and Criteria for Diagnosis of Diseases of the Heart and Great Vessels, ed 8. New York, New York Heart Association, 1979; with permission.
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follow a polygenic/multifactorial mode of inheritance with a 2 to 5 per cent risk of recurrence. (A few important exceptions are Marfan's syndrome and idiopathic hypertrophic subaortic stenosis that follow an autosomal dominant mode of inheritance.) SPECIFIC CARDIAC LESIONS Aortic Stenosis Patients with mild to moderate degrees of aortic stenosis tolerate pregnancy well. The major functional problem associated with this lesion is the maintenance of adequate cardiac output. Most patients experience an improved cardiac output with the plasma volume increases of pregnancy. Patients with severe disease (aortic gradients of greater than 100 mm Hg) are at significant risk in pregnancy; the reported mortality in these patients is 17 per cent. 5 Significant decreases in preload will lead to a fall in cardiac output and, potentially, myocardial ischemia, cerebral ischemia, and sudden death. Hypovolemia and hypotension must be avoided in these patients. Spinal anesthetic agents are contraindicated, because the resultant sympathetic block may produc~ hypotension. The greatest risk to these patients is during delivery or termination of pregnancy. 5 A 40 per cent maternal mortality has been reported with voluntary interruption of pregnancy in the early second trimester. Labor and delivery in these patients is best managed with invasive cardiac monitoring. Adequate preload must be maintained and hypotension avoided. Pulmonary capillary wedge pressures are best maintained at a slightly higher level to serve as a preload reserve against potential blood loss during delivery. 12 These patients require bacterial endocarditis prophylaxis. It is advisable that patients with hemodynamically significant degrees of aortic stenosis undergo corrective surgery (either valvuloplasty or valve replacement) prior to becoming pregnant. Aortic Insufficiency Aortic insufficiency is well tolerated by the pregnant patient. This lesion, however, is often associated with mitral valvular lesions as a result of rheumatic fever. If a patient demonstrates signs of pulmonary congestion, therapy should be directed at physical activity restriction and volume reduction. Digitalis and diuretics are sometimes required in the management of these patients. Mitral Stenosis Mitral stenosis is most often rheumatic in origin. This lesion may become life-threatening during pregnancy, as left atrial outflow obstruction leads to decreased left ventricular diastolic filling resulting in a fixed cardiac output. With increased pulmonary vascular volume in pregnancy, pulmonary congestion and pulmonary edema may result. With large increases in left atrial volume, atrial arrhythmias (atrial flutter/fibrillation) are seen. Stagnant blood within the distended left atrium may lead to thrombus formation and systemic arterial emboli. Patients with atrial fibrillation may benefit from hep-
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arin anticoagulation. Functional decompensation during pregnancy is treated wtih fluid restriction, digitalis, and possibly diuretic therapy. Labor, delivery, and the immediate postpartum period provide the most critical stress for these patients. The 300 to 500 ml autotransfusion from the utero-placental circulation that occurs at the time of delivery may produce acute pulmonary edema. Those patients with NYHA classes III and IV disease should be monitored with invasive pulmonary artery catheterization; fluid status should also be closely followed. It is important to remember that, in patients with mitral stenosis, pulmonary capillary wedge pressure is not an adequate estimate ofleft ventricular diastolic filling pressure. Monitoring of cardiac output is indicated to assess left ventricular function, especially if volume reduction with diuretics is undertaken. 15,16 The ideal mode of delivery is vaginal with regional anesthesia (epidural) for pain reduction in the first and second stage of labor. Tachycardia must be avoided as left ventricular end-diastolic volume may become reduced. In the past, elective mid-forceps operations (with a shortened second stage of labor) have been advocated. With close hemodynamic monitoring, these potentially harmful operations may be avoided, and these patients may be allowed to valsalva during the second stage of labor to help effect fetal expulsion. In hemodynamically severe forms of mitral stenosis, mitral commissurotomy or valve replacement may be undertaken during pregnancy.17 Recently, a successful percutaneous balloon valvuloplasty has been performed at our institution in a pregnant patient with hemodynamically significant mitral stenosis at 34 weeks' gestation. 25 This new technology may prove beneficial in the management of pregnant patients with severe disease. These procedures may reduce the need for invasive thoracic procedures during pregnancy. Mitral Insufficiency Patients with mitral regurgitation do well in pregnancy. Unlike mitral stenosis, rheumatic etiologies are rare. Echocardiography is often helpful in identifying the underlying etiology.ll Mitral valve prolapse (that occurs in approximately 10 per cent of pregnancies) is a well-tolerated, benign form of mitral insufficiency. Therapeutic interventions are rarely necessary. .56 Patients who have vegetative endocarditis as the underlying etiology of their valvular lesion require prolonged antibiotic prophylaxis throughout pregnancy with penicillin or erythromycin, as endocarditis is a common complication. Congenital Heart Disease Congenital cardiac disease is becoming the most common cardiac problem encountered in the perinatal patient. This is probably because corrective surgical procedures have allowed these patients to reach child-bearing age. It is important to recognize the genetic nature of these lesions and that children of affected individuals are at risk for having similar cardiac lesions, as well as other congenital malformations. 4 S,49 In utero echocardiography may be beneficial in the antenatal diagnosis of these conditions. Genetic counseling is required because of the possibility of transmission of these cardiac defects to the offspring.
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LEFT-TO-RIGHT SHUNTS Ventricular Septal Defect (VS D) Most patients with VSDs are diagnosed in childhood with a loud systolic murmur characteristic of this lesion. The majority of these patients undergo corrective surgery prior to reaching the child-bearing ages. Patients with uncorrected lesions, in the absence of pulmonary hypertension, do well in pregnancy. Care in management to avoid fluid overload is needed. Most VSD lesions are inherited via the polygenic/multifactorial route; the risk of fetal congenital lesion is 3 to 5 per cent. Finally, prophylaxis for bacterial endocarditis is needed at the time of delivery. Atrial Septal Defects (ASD) Atrial septal defects of the ostium secundum are one of the most common congenital cardiac lesions found in women of child-bearing age. 49 Pregnancy is well tolerated in these patients. The risk of developing bacterial endocarditis with ASD is low, and antibiotic prophylaxis at the time of delivery is not warranted. There is a 2 to 3 per cent chance of fetal congenital heart disease in patients with this cardiac lesion. 49 Patent Ductus Arteriosus Those patients with patent ductus arteriosus tolerate the hemodynamic stress of pregnancy well. When pulmonary hypertension is associated with this lesion, however, the patient is at significant risk (see pulmonary hypertension). Bacterial seeding is common in these patients and antibiotic prophylaxis is necessary during delivery. The risk of fetal congenital heart disease is 3 to 4 per cent. 49 RIGHT-TO-LEFT SHUNTS Coarctation of the Aorta Patients with surgically corrected aortic coarctation withstand the stress of pregnancy with little difficulty. 18.27 Those rare patients who enter pregnancy with an uncorrected lesion are at risk for aortic dissection, cerebral hemorrhage, and end-organ hypertensive complications. The risk of cerebral hemorrhage is noted in those individuals with associated cerebral vascular aneurysms. The risk of maternal mortality is 3 to 6 per cent. 18 Occasionally, a bicuspid aortic valve is correlated with aortic coarctation. These patients have the highest risk during pregnancy. 57 The risk of associated fetal congenital heart lesion is 2 per cent. 49 Tetralogy of Fallot Tetralogy of Fallot is the most common right-to-Ieft shunt found in women of child-bearing age. 1S . 4S The lesion is composed of the tetrad of pulmonic valvular stenosis, right ventricular hypertrophy, an overriding aorta, and a ventricular septal defect. Pregnant patients with tetralogy of Fallot have a risk of increased shunting as systemic vascular resistance decreases. Patients who have high hematocrit, greater than 65 per cent, syn-
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copal episodes, a Pa0 2 less than 70 mm Hg, and high right heart pressures have a poor prognosis in pregnancy.1S Venous return and right-sided enddiastolic volume are critical in maintaining adequate hemodynamic function in these patients. The times of most physiologic stress to these patients are during labor, delivery, and the immediate postpartum period. Blood loss with postpartum hemorrhage is particularly dangerous, as venous return is impaired. 3 .5 ,4,5 Surgically corrected patients with normal oxygen saturation are able to successfully complete pregnancy with minimal risks. The fetal risk of congenital heart disease is 4 per cent.48 Eisenmenger's Syndrome Patients with high pulmonary vascular resistance due to intracardiac shunting (Eisenmenger's syndrome) are unable to withstand the hemodynamic stress of pregnancy. Sudden death due to hypoxemia (secondary to impaired pulmonary perfusion) can occur ante-, intra-, or postpartum. The published maternal mortality with this lesion is 50 to 70 per cent. 26,47 Patients with Eisenmenger's syndrome should be advised not to become pregnant. Voluntary termination of pregnancy may be considered in these patients because of an extremely high maternal, as well as perinatal, mortality rate. 26,47 Patients who maintain pregnancy require anticoagulation and endocarditis antibiotic prophylaxis during delivery, 53 Gleicher et al26 have reported a 34 per cent maternal mortality with vaginal delivery and a 75 per cent maternal mortality associated with cesarean section. This observation is due to an increased blood loss and decreased venous return, in patients undergoing cesarean section, Pulmonary Hypertension Patients with hemodynamically significant pulmonary hypertension, regardless of etiology, should be advised not to become pregnant. These patients have as much as a 50 per cent risk of maternal mortality and a 40 to 50 per cent risk of perinatal mortality. 32,41 As with Eisenmenger's syndrome, voluntary termination of pregnancy may be considered. First trimester terminations with dilatation and curettage are well tolerated. Patients in the second trimester have a greater risk associated witb the termination procedure; the procedure of choice is dilatation and evacuation, Abortifacients, such as prostaglandins and hypertonic saline, are contraindicated. 41 Patients with pulmonary hypertension must be carefully monitored during lab or. Blood loss and hypotension should be avoided and invasive pulmonary artery catheterization is indicated, Pulmonary capillary wedge pressures are best maintained at elevated levels to insure adequate left ventricular preload. 17 Regional anesthetics should be used with caution since sympathetic blockage with vasodilation will reduce venous return. Recent reports have advocated an anesthetic technique utilizing epidural narcotic agents (such as morphine or fentanyl) that do not effect peripheral vasodilatation, I This may be the anesthetic of choice in these patients. As with Eisenmenger's syndrome, the vaginal route of delivery is safer and is preferred over cesarean section.
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Peripartum Cardiomyopathy Patients with peripartum cardiomyopathy present with sudden onset of congestive heart failure with a history of no previous cardiac disease in the last 4 weeks of pregnancy or the first 6 months postpartum. The etiology of this condition remains unknown. The diagnosis is established by demonstrating decreased cardiac output due to impaired left ventricular function. 19 These patients require investigation for other conditions leading to dilated congestive cardiomyopathy-that is, viral cardiomyopathy, ischemic heart disease, and amyloidosis. A characteristic histologic picture is observed on myocardial biopsy.36.42 The "classic" patient is in her mid-30s, black, multiparous, with a multiple gestation; this condition, however, has been observed in many varied patients. The diagnosis is primarily one of exclusion; only after all other causes of sudden congestive failure have been ruled out can the diagnosis of peripartum cardiomyopathy be assigned. These patients are best managed with sodium and fluid restriction, decreased physical activity, positive inotropic agents (digitalis), and diuretic therapy. Over 60 per cent of patients will recover and return to normal cardiac function. If the symptoms persist for 6 months beyond delivery, the prognosis is poor,42.71 and cardiac transplantation may become necessary. Patients with periportal cardiomyopathy should be advised that there is a 50 to 60 per cent recurrence risk and that future pregnancy is not advisable. Coronary Artery Disease Pregnant patients with ischemic heart disease are uncommon since coronary artery disease is rare in women of child-bearing age. In a review of 68 cases of myocardial infarction during pregnancy, Hankins et apo reported that only nine patients (13 per cent) had known coronary artery disease antedating their pregnancy. The majority of patients who suffer ischemic heart disease during pregnancy will have their first manifestation of their disease during pregnancy. The hemodynamic demands of pregnancy upon the myocardium may serve as a stress to the coronary circulation producing ischemia in patients with previously asymptomatic disease. The overall mortality in these patients is 35 per cent with patients who present with ischemia in the third trimester having the highest mortality, 45 per cent.30 Management consists of oxygen, vasodilator therapy, and pain relief. The stress of labor is best avoided, and elective induction within 2 weeks of infarction is contraindicated. Delivery is managed with conduction anesthesia and a shortened second stage, with elective forceps delivery being indicated to minimize myocardial demands during the process of delivery. 31 Cardiac Arrhythmias Patients with cardiac dysrhythmias that antedate pregnancy are able to tolerate pregnancy. The major concern with these patients is the alteration of their cardiotoxic drugs for both fetal and maternal indications. Digitalis, procainamide, and quinidine have not been shown to be teratogenic or harmful to the fetus and thus may be used. 59 Beta-blockers also may be used, although there is a risk of transient neonatal hypoglycemia and hypotonia. Controversy exists whether beta-blockers are implicated in impaired fetal
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growth. Recent data suggest that the underlying disease state, and not the beta-blockers, are the etiology of the correlation between these drugs and intrauterine growth retardation. 67 When indicated, calcium channel blockers may be used in pregnancy. There have been isolated case reports implicating these agents with sudden intrauterine fetal death. Other recent reports have indicated that oral antiarrhythmic agents with action against ventricular ectopy, such as flecainide and mexiletine, may be used in pregnant patients with recurrent ventricular tachyarrhythmias. 28 Although no adverse fetal complications have been reported to date, these agents must be used with caution because the number of patients exposed to these drugs in pregnancy remains small. Patients with supraventricular tachyarrhythmias resistant to medical therapy may undergo Die cardioversion during pregnancy, as the risk to the fetus with low to moderate energy settings appears small. 62 Prosthetic Heart Valves (Anticoagulation) Patients who have undergone corrective surgery for valvular heart disease who have regained normal cardiac hemodynamic function usually tolerate pregnancy well, although their pregnancies remain at higher risk. 4.10.11.50 Patients with mechanical prosthetic valves require full anticoagulation and bacterial endocarditis prophylaxis during pregnancy. As there is a physiologic increase in coagulation factors during pregnancy, these patients are at greater risk for valvular thrombosis and sudden death. 37.51.61 Anticoagulation with warfarin and its derivatives are contraindicated during pregnancy since these agents readily cross the placenta and are teratogenic to the fetus. First trimester exposure to warfarin has been associated with the condition termed warfarin embryopathy. 8.13.29.64 This syndrome includes mid-face hypoplasia, mental retardation, optic atrophy, blindness, and chondrodysplasia punctata (stippled epiphyses).63,64,74 Previously, second and early trimester warfarin use had been advocated, but recent data suggest that warfarin use during pregnancy may cause central nervous system abnormalities (believed secondary to intrauterine intracranial bleeding). It is therefore recommended that warfarin be avoided throughout pregnancy. The anticoagulant of choice is heparin. Due to its molecular structure, heparin does not cross the lipoprotein membranes of the placenta and is associated with no adverse fetal effects. Adverse maternal side effects associated with prolonged heparin administration in pregnancy have been reported. These include reversible bone demineralization, thrombocytopenia, hyperkalemia, and adverse dermatologic reactions I4 ,21,33; these reactions, fortunately, are uncommon. The subcutaneous route of administration will allow for outpatient management. Heparin may be administered as two to three subcutaneous boluses of 10,000 to 20,000 units to maintain the activated partial thromboplastin time (aPPT) 1. 5 to 2 times above normal. 46 As subcutaneous absorption may lead to wide fluctuations in the coagulation times, an alternative method of continuous subcutaneous heparin administration via an infusion pump has been shown to be useful. 46 Patients may resume warfarin therapy in the postpartum period since only small amounts of warfarin have been shown to be excreted in breast milk. These patients may breast-feed their infants if they wish. 74 However, it is essential to observe these patients
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Table 3. American Heart Association Recommendations for Bacterial Endocarditis Prophylaxis at the Time of Deli1Jery Ampicillin, 2 g, IV Gentamicin, 1.5 mg/kg, IV/I~l In Penicillin-allergic Patients: Vancomycin, 1 g, IV Gentamicin, 1.5 mg/kg, IV/I M To be administered in three doses every 8 hours
carefully, as there is a risk of valvular thrombosis and sudden death if their anticoagulation becomes subtherapeutic. LABOR AND DELIVERY MANAGEMENT
The management oflabor and delivery in the patient with cardiac disease is dictated by the functional status of the patient. Those patients with NYHA functional classes I and 11 may be allowed to labor and deliver with minimal intervention. Close observation of intake, output, and cardiac rate and rhythm are important. Pain relief with conduction regional anesthetic is indicated to prevent tachycardiac responses. Postpartum hemorrhage and excessive blood loss should be avoided. Invasive cardiac monitoring may be used on an individual basis when indicated, although it is not commonly needed in these patients. Patients with NYHA functional classes III or IV, or patients with hemodynamically significant pulmonary hypertension, are at higher risk during labor and delivery. The optimal route of delivery is a controlled vaginal delivery with very close observation of fluid status. As volume shifts and blood losses are greater for cesarean section, these procedures should be performed only for the usual fetal or obstetrical indications. The preload, afterload, and myocardial work must be carefully observed. Invasive monitoring with pulmonary artery catheters and radial artery catheters are often indicated to maintain close hemodynamic observation of these patients. Pain relief is essential and regional anesthetics may be used; epidural narcotic anesthesia may be useful during labor. I When indicated, bacterial endocarditis prophylaxis should be administered following the delivery of the fetus (Table 3). CONCLUSION
With a thorough understanding of the hemodynamic alterations of pregnancy and the pathophysiology of cardiac disease, the clinician can best serve patients with cardiac disease. Prior to undertaking pregnancy, patients with cardiac disease require complete investigation and counseling regarding the risks they shall undertake in pregnancy. Investigative procedures, drug therapy, and invasive maternal procedures may become necessary during pregnancy. It is important to understand both the maternal and fetal risks associated with these procedures. Labor, delivery, and the immediate
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postpartum period are times of particular stress in a number of cardiac lesions. Techniques of invasive hemodynamic monitoring have improved the prognosis and management of patients with significant cardiac lesions in pregnancy.
REFERENCES 1. Abboud JK. Raya J, Noueihed R, et al: Intrathecal morphine for relief of labor pain in a parturient with severe pulmonary hypertension. Anesthesiology 59:477, 1983 2. Adams JQ, Alexander AY!: Alterations in cardiovascular physiology during labor. Am J Obstet Gynecol 12:542~549, 1958 3. Ansell JE, Price JM, Shah S, et al: Heparin-induced thrombocytopenia: What is its real frequency? Chest 88:878~882, 1985 4. Antunes MJ, Myer IG, Santos LP: Thrombosis of mitral valve prosthesis in pregnancy: Y!anagement by simultaneous caesarean section and mitral valve replacement. Case report. Br J Obstet Gynaecol 91:716~ 718, 1984 5. Arias F, Pineda J: Aortic stenosis and pregnancy. J Reprod Med 20:229, 1978 6. Bader RA, Bader ME, Rose DJ, et al: Hemodynamics at rest and during exercise in normal pregnancy as studied by cardiac catheterization. J Clin Invest 34:1524, 1955 7. Barron WM, Lindheimer MD: Renal sodium and water handling in pregnancy. Obstet Gynecol Ann 13:35~69, 1984 8. Becker MH, Geniesser NB, Finegold Y!, et al: Chondrodysplasia punctata: Is maternal warfarin therapy a factor? Am J Dis Child 129:356~359, 1975 9. Bonnar J: Longterm self-administered heparin therapy for prevention and treatment of thromboembolic complications in pregnancy. In Kakkar VV, Thomas DP (eds): Heparin Chemistry and Clinical Usage. New York, Academic Press, 1976 10. Buxbaum A, Aygen MM, Shabin W, et al: Pregnancy in patient with prosthetic heart valves. Chest 59:639, 1971 11. Casenegra P, Auiles G, Maturana G, et al: Cardiovascular management of pregnant women with a heart valve prosthesis. Am J Cardiol 36:802, 1975 12. Caton WL, Roby CC, Reid DE, et al: The circulating red cell volume and body hematocrit in normal pregnancy and the puerperium. Am J Obstet Gynecol 61:1207, 1951 13. Chong MKB, Harvey D, DeSwiet M: Follow-up study of children whose mothers were treated with warfarin during pregnancy. Br J Obstet Gynaecol 91:1070~1O73, 1984 14. Christianson RE: Studies on blood pressure during pregnancy. l. Influence of parity and age. Am J Obstet Gynecol 125:509~513, 1976 15. Clark SL, Ph elan JP, Greenspoon J, et al: Labor and delivery in the presence of mitral stenosis: Central hemodynamic observations. Am J Obstet Gynecol 152:984, 1985 16. Clark SL: How labor and delivery influence mitral stenosis. Con temp Ob/Gyn 27: 127, 1986 17. Clark SL: Labor and delivery in the pregnant patient with structural cardiac disease. Clin Perinatol 13:697, 1986 18. Deal K, Wooley CF: Coarctation of the aorta and pregnancy. Ann Intern Y!ed 78:706, 1973 19. Demakis JG, Rahimtoola SH: Peripartum cardiomyopathy. Circulation 44:964~968, 1971 20. DeSwiet M: The cardiovascular system. In Hytten FE, Chamberlain GVP (eds): Clinical Physiology in Obstetrics. Oxford, Blackwell Scientific, 1980, pp 3~42 21. DeSwiet M, Dorrington WP, Fidler J, et al: Prolonged heparin therapy in pregnancy causes bone demineralization. Br J Obstet Gynaecol 90:1129~1134, 1983 22. Dresdale DT, Schultz M, Michtom RJ: Primary pulmonary hypertension. 1. Clinical and hemodynamic study. Am J Med 11:686~705, 1951 23. Elkayam U, Gleicher N: Cardiovascular physiology of pregnancy. In Elkayam U, Gleicher E (eds): Cardiac Problems in Pregnancy. New York, Alan R Liss, 1982, pp 5-26 24. Ferris TF, Stein JH, KauHinan J: Uterine blood flow and uterine renin secretion. J Clin Invest ,sl:2827~2833, 1972 205. Gianopoulos JG, Leya F, Meyer W: Mitral balloon valvuloplasty in pregnancy. [Submitted for pu hlication 1 26. Gleicher N, Midwall J, Hochberger D, et al: Eisenmenger's syndrome and pregnancy. Obstet Gynecol Surv 34:721, 1979
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