LAW No. 167 of 16 JULY 1997 OF THE REPUBLIC OF KAZAKHSTAN THE CRIMINAL CODE OF THE REPUBLIC OF KAZAKHSTAN 2 page

CONGENITAL COMPLETE HEART BLOCK

CONGENITAL COMPLETE HEART BLOCK. This uncommon congenital conduction defect permits survival into childbearing age, and about one-half of the patients are female.5 Asymptomatic young women usually experience an uneventful pregnancy, provided that the QRS duration is not prolonged and the rate response to exercise is satisfactory.159,163,164 Stokes-Adams attacks occasionally occur during gestation, and the heart and circulation may not respond appropriately to the volatile demands of labor and delivery.

EBSTEIN’S ANOMALY OF THE TRICUSPID VALVE

EBSTEIN’S ANOMALY OF THE TRICUSPID VALVE. About half of the patients with this malformation are women, and the majority reach adulthood.5 The functionally inadequate right ventricle, already volume-overloaded by tricuspid regurgitation, copes poorly with the gestational increase in cardiac output.165 Atrial tachyarrhythmias occur in approximately one-third of nonpregnant patients with Ebstein’s anomaly and are potential hazards during pregnancy.166 Wolff-Parkinson-White bypass tracts set the stage for excessively rapid ventricular rates in response to atrial fibrillation or flutter (Fig. 30–7 Fig. 30–7 ). The consequences can be catastrophic. Cyanosis in Ebstein’s anomaly (right-to-left interatrial shunt) may first become manifested during pregnancy because of a rise in right ventricular filling pressure. The right-to-left shunt increases the risk of paradoxical embolization, and the hypoxemia increases the risk to the fetus.

THE POSTOPERATIVE PATIENT

There is a consensus that successful surgery before gestation can be pivotal in reducing maternal risks of congenital heart disease. Surgery should therefore be anticipatory. The objectives of reparative surgery are to increase the safety and success of pregnancy, to preserve the health of the mother, and to reduce the risk to the fetus. Closure of an ostium secundum atrial septal defect in children or young adults permits pregnancy without maternal risk. The complication of paradoxical embolization from the inferior vena cava is eliminated. However, an increase in incidence of atrial tachyarrhythmias should be considered when the defect is closed after young adulthood.

Division of a small nonpulmonary hypertensive patent ductus early in life is curative. Division of a nonrestrictive or moderately restrictive ductus is sometimes followed by incomplete resolution of elevated pulmonary vascular resistance or by less than adequate functional recovery of the volume-overloaded left ventricle, important residua that might confront the pregnant woman. In any event, division of a patent ductus eliminates the risk of infective endocarditis.

Successful response of congenital pulmonary valve stenosis to balloon dilatation or to direct repair permits the pregnant woman to anticipate a normal pregnancy except for a low, if not altogether absent, risk of infective endocarditis. Mild-to-moderate low-pressure postinterventional pulmonary regurgitation is not a concern, with few exceptions. Balloon dilatation has proven efficacious during pregnancy (Fig. 30–9 Fig. 30–9 ).

After repair of coarctation of the aorta, the risk of pregnancy depends on relief of the isthmic obstruction (and reduction of systemic blood pressure), the surgical technique, and whether or not a bicuspid aortic valve coexists. To what extent correction of coarctation reduces the hazard of gestational rupture of an aneurysm of the circle of Willis is open to question. The histology of the aorta immediately distal to the coarctation resembles that of cystic medionecrosis, and balloon dilatation injures this already vulnerable aortic segment.20 Relief of the isthmic obstruction by partial resection and roofing with a graft leaves the vulnerable postcoarctation aortic segment largely in place. The procedure of choice in women is resection that includes the segment of aorta distal to the coarctation, with end-to-end anastomosis. Should a bicuspid aortic valve coexist, two additional postoperative concerns persist: susceptibility to infective endocarditis and the risk inherent in the histological abnormalities of the aortic root.

Surgical relief or balloon dilatation of congenital bicuspid aortic stenosis (Fig. 30–10 Fig. 30–10 ) significantly lowers the risk of pregnancy (see earlier), but not the risk of infective endocarditis. In the presence of hemodynamically significant bicuspid aortic regurgitation, it is usually better to advise pregnancy before aortic valve replacement, provided that left ventricular function is normal or nearly normal. If a stenotic or incompetent aortic valve requires replacement in a woman of childbearing age, a tissue valve has the advantage of good hemodynamics without the need for anticoagulants (but with the caveats commented upon later).

Pregnancy after repair of Fallot’s tetralogy is accompanied by a gratifyingly small risk, especially when outflow obstruction is relieved without inducing significant low-pressure pulmonary regurgitation. Elimination of cyanosis increases the probability of successful conception,167 improves the stability of pregnancy, and results in normal fetal growth and development. Postoperative electrophysiological sequelae cannot be ignored but are comparatively infrequent when successful repair is accomplished at a young age (see [For More Information] ).

Closure of a nonrestrictive or moderately restrictive perimembranous ventricular septal defect in infancy or early childhood serves to preclude the development of pulmonary vascular disease and to relieve the left ventricle of volume overload. Pregnancy can be anticipated with optimism. Postoperative electrophysiological sequelae are exceptional.

A pacemaker is occasionally required in young women with congenital complete heart block, but with relative confidence that pregnancy can then safely proceed if ventricular function is normal, which is usually the case. Although a dual-chamber pacemaker is preferable, a fixed-rate system provides satisfactory physiological support.

Surgical repair of Ebstein’s anomaly of the tricuspid valve ideally takes the form of reconstruction using the large mobile anterior tricuspid leaflet to create a competent unicuspid atrioventricular valve. Active or potential bypass tracts are eliminated by surgical dissociation of right atrium from right ventricle (Fig. 30–7 Fig. 30–7 ). The maternal risk of pregnancy, including susceptibility to infective endocarditis, is reduced but not eliminated.

Pregnancy after repair of certain forms of complex cyanotic congenital heart disease is now a practical objective. However, menstrual patterns of women who were cyanotic before operation differ significantly from normal women, implying abnormalities of gynecological endocrinology that may influence fertility.167 After a Fontan procedure, a twofold increment in cardiac index can usually be achieved in response to isotonic exercise.168 The corollary is that women who have undergone successful Fontan repairs and have good if not normal ventricular function confront the physiological burden of pregnancy with circulations that potentially possess adequate hemodynamic reserve. However, other variables may influence outcome.133

Medical Management of the Pregnant Woman with Congenital Heart Disease

PRENATAL CARE

PRENATAL CARE. A major objective of medical management is to minimize the factors that encroach upon the limited circulatory reserve of pregnant women with heart disease. Cardiac reserve is encroached upon by the hemodynamic burden of pregnancy and by the heart disease itself. Anxiety is a special concern in the primigravida as she anticipates her first gestational experience. The expectant mother should be prepared for what awaits her during pregnancy, labor, delivery, and puerperium in order to decrease if not eliminate fear of the unknown. Diuretics can be used judiciously for the edema of cardiac failure but should not be used for the edema of normal pregnancy.159 The pregnant woman with heart disease should limit herself to moderate isotonic exercise. Heat and humidity add to the hemodynamic burden; a dry cool atmosphere is therapeutic. The physiological anemia of pregnancy must be distinguished from pathological anemia, and the latter assiduously addressed. Meticulous leg care reduces the gestational tendency for lower-extremity venous stasis and the attendant risk of thromboembolism. Passive standing should be avoided, the supine position minimized (compression of the inferior vena cava by the enlarged uterus), and the pregnant woman should minimize or avoid sitting with knees flexed and legs dependent. As term approaches, an important element in reducing anxiety is assurance that the pain of labor and delivery will be minimized.

The efficacy of oxygen administration during gestation in cyanotic women is open to question, with little or no convincing evidence of benefit to the mother. There is less-than-convincing evidence that oxygen administration exerts a favorable effect on growth retardation of the fetus in cyanotic women.

Maternal mortality in pregnant women with heart disease has been coupled with functional class. Symptoms associated with congenital heart disease, especially cyanotic, have prompted the use of the functional classification shown in Table 30–1 Table 30–1 . In addition to and apart from symptoms and functional limitations, certain congenital cardiac malformations impose such a formidable threat to maternal survival that pregnancy is proscribed or should be interrupted. Of the two major maternal cardiac risks—pulmonary vascular disease and pulmonary edema—the former is more relevant to congenital heart disease. Primary pulmonary hypertension epitomizes this risk (see Chap. 25 ), but pulmonary vascular disease in any context is a major hazard, limiting if not precluding rapid adaptive responses to the circulatory changes of pregnancy and to the volatile changes during labor, delivery, and the puerperium.

LABOR AND DELIVERY

LABOR AND DELIVERY. In women with functionally mild unoperated lesions and in patients after successful cardiac surgery, management of labor and delivery is the same as for normal pregnant women. The need for infective endocarditis prophylaxis during routine delivery in pregnant cardiac patients has been questioned because of the low incidence of bacteremia that accompanies a normal uncomplicated vaginal delivery.169 It should not be assumed, however, that a given delivery will be uncomplicated. An episiotomy and vacuum extraction are, strictly speaking, not “normal.” Accordingly, pregnant women with cardiac lesions susceptible to infective endocarditis should receive appropriate antibiotic prophylaxis from the onset of labor through the third or fourth postpartal day.170

For pregnant women with functionally important congenital cardiac disease—unoperated or operated—the management of labor, delivery, and the puerperium is crucial if risk is to be minimized. The first necessity is to underscore the beneficial effects of induced vaginal delivery. Cesarean section should be reserved for cephalopelvic disproportion, for breech presentation, or for preterm labor in a woman receiving coumadin anticoagulation. Cesarean section results in about twice the blood loss as vaginal delivery, in addition to the risks of wound and uterine infection, thrombophlebitis (delayed ambulation), and potential postoperative complications.

Amniocentesis around the 37th week determines whether or not fetal lung maturity has been achieved and whether induced delivery can safely proceed. The pregnant woman is then admitted for induction, with delivery planned as far as possible during the working day so that a high-risk obstetrician, neonatologist, and cardiologist can more readily be available. On admission, prostaglandin vaginal gel is applied to soften and dilate the cervix.159 Laminaria, derived from the stems of a special seaweed, can be used for the same purpose because of its hydrophilic properties. Oxytocin may be required for augmentation of uterine contractions that are usually initiated by absorbed prostaglandin. The sequence of cervical softening and dilatation precedes the onset of uterine contractions, as in normal spontaneous vaginal delivery.

After contractions are under way, artificial rupture of the membranes is performed. The woman should labor in a lateral decubitus position in order to attenuate the hemodynamic fluctuations provoked by major uterine contractions in the supine position. Meperidine is used selectively for relief of pain and apprehension. The anesthetic of choice is a lumbar epidural preparation, such as fentanyl, that exquisitely controls pain without reducing the strength of uterine contractions, which are monitored together with fetal rate (Fig. 30–9A Fig. 30–9A ). The fetus is allowed to pass through the pelvis in response to the force of uterine contractions unsupplemented by straining in order to avoid the undesirable circulatory effects of the Valsalva maneuver. Delivery is assisted by vacuum extraction and low forceps.

Systemic arterial pressure should be monitored during labor, because lumbar epidural anesthetics may cause hypotension. In patients with Fallot’s tetralogy or Eisenmenger’s complex, a sudden fall in systemic vascular resistance poses a special threat. Use of a flotation catheter for hemodynamic monitoring is an individual cardiological decision, rather than routine policy. In Eisenmenger’s complex, for example, the risks of a flotation catheter far outweigh the benefits.171 Oxygen is often intuitively administered during labor, especially in cyanotic women, although without proven efficacy.

After expulsion of the placenta, bleeding is reduced by uterine massage. If intravenous oxytocin is used, the drug should be administered slowly because of its potential hypotensive effect. In the postpartum period, meticulous leg care, use of elastic support stockings, and early ambulation are important preventive measures that reduce the risk of thromboembolism.

BREAST FEEDING

BREAST FEEDING. This practice may encroach upon cardiac reserve and increase the risk of mastitis and bacteremia. Nursing should therefore be advised with caution in patients with congenital cardiac disease, and its duration should be minimized. Engorgement of the breasts and suppression of lactation are managed with binding, cold packs, and analgesics rather than with bromocriptine, which can cause hypotension.

Medical Management of the Fetus

Maternal congenital heart disease exposes the fetus to risks that threaten its intrauterine viability and to risks of potential congenital and developmental malformations.172 Intrauterine viability is influenced by the functional class of the mother (with the qualifications noted above), by maternal cyanosis, and by oral anticoagulants. Maternal cyanosis threatens the growth, development, and viability of the fetus and materially increases fetal wastage, dysmaturity, and prematurity. The risk to the fetus of oral anticoagulants has not been satisfactorily resolved, so the need for anticoagulation should be minimized (see [For More Information] ). Valve reconstruction is recommended in women of childbearing age. A bioprosthetic valve obviates the need for anticoagulants but subjects the patient to subsequent reoperation. In addition, there is concern that pregnancy itself might accelerate degeneration of a bioprosthetic valve because of the inherent gestational changes in connective tissue. Aspirin is not a viable alternative to anticoagulants because of its potential for closing the fetal ductus and because of low efficacy.

There is no consensus on how best to administer anticoagulants. It is currently believed that the risk of fetal wastage from heparin is not of the same order as from coumadin,173 previous reports notwithstanding. Whichever regimen of heparin and/or coumadin is chosen, the patient and her partner should be so advised before conception. There is a mounting consensus that warfarin should be replaced with heparin before conception in order to avoid the teratogenic risk of coumadin in early gestation.

The change from coumadin to heparin is best accomplished in the hospital. A nurse specialist instructs the patient and her partner on the technique of subcutaneous administration of heparin using a short 25-gauge needle and an abdominal site for injection at right angles to the elevated skin surface. The needle should be withdrawn slowly, and the site should not be massaged.

Heparin can either be continued throughout gestation (provided that the anticoagulant response is carefully monitored) or replaced with warfarin in the second trimester, returning to heparin in the 36th week. Because of harmful effects that coumadin might exert on the fetal central nervous system—which continues to develop throughout gestation—it has been argued that heparin is the preferred drug because it does not cross the placental barrier and is therefore not teratogenic either during initial organogenesis or during subsequent maturation of the higher centers of the brain. That is, the risk of coumadin lies not only in warfarin embryopathy but potentially in the effect of the oral anticoagulant on central nervous system development.174 In light of concern that the risk of embryopathy varies directly with blood level, warfarin dosage should be monitored using the International Normalized Ratio (INR) in order to achieve a therapeutic range at the lowest possible dose.175

Preterm labor in a pregnant woman taking warfarin threatens the fetus with fatal hemorrhage because fetal anticoagulation cannot be promptly reversed. Emergency cesarean section is required if the fetus is to be saved. Maternal administration of vitamin K and infusion of fresh frozen plasma do not reverse fetal anticoagulation quickly enough to obviate fatal hemorrhage, but fresh frozen plasma should be administered to the newborn. There are, however, four concerns regarding the administration of heparin throughout pregnancy173: (1) greater difficulty in achieving a stable therapeutic response; (2) the inconvenience of parenteral administration, an inconvenience that the woman may not be prepared to sustain; (3) the risk of heparin-induced thrombocytopenia; and (4) the risk of bone demineralization.

Extracorporeal circulation is associated with a high incidence of fetal wastage, but cardiac surgery is rarely employed during gestation, especially in the pregnant woman with congenital heart disease. Should cardiac surgery be necessary, it is best to await the 25th to 26th week of gestation.

In addition to threats to its intrauterine viability, the fetus is exposed to risks that take the form of genetic parental transmission, teratogenic effects of certain cardiac drugs, and the harmful effects of certain environmental toxins. A substantial majority of congenital heart diseases cannot be attributed to either a syndrome or a single-gene defect that exhibits mendelian inheritance.172 A number of studies have concluded that the risk of recurrence of congenital cardiac defects in offspring is greater if the mother rather than the father is the affected parent.172 A hypothesis that might account for this pattern is cytoplasmic or maternal inheritance based on the observation that mitochondrial DNA is inherited only from the mother.172 A second hypothesis, “parental imprinting” or “genomic imprinting,” refers to gene expression that varies according to its maternal or paternal origin.176 The imprinting factor is believed to be DNA methylation.

Exercise Before and After Surgery or Interventional Catheterization

Certain types of congenital disorders of the heart or circulation expose patients to the risk of complications or sudden death during strenuous exercise or competitive sports.177 Consideration must be given to (1) the type, intensity, and duration of exercise; (2) the risk of body collision inherent in a given type of athletic activity; (3) the training program (conditioning) required for a given sport; (4) the emotional stress that the participant experiences in anticipation of or during a particular sport event; (5) the risk of injury to either the participant or spectators if the athletic activity induces loss of consciousness; and (6) the sometimes arbitrary distinction between competitive and recreational athletics.178

Two general types of exercise are recognized: isotonic (dynamic) and isometric (static).2 Isotonic exercise is associated with changes in muscle length and with rhythmic muscular contractions that develop comparatively little force. A steady state can be achieved. Isometric exercise results in sudden development of a comparatively large force with little or no change in muscle length; a steady state cannot be achieved, even temporarily. There is usually a continuum between the two types, with most physical activity incorporating isotonic and isometric components. The risk incurred by conditioning (training) may equal or exceed the risk of the competitive event itself. The heightened emotional response of an athlete before or during a sporting event may trigger a disturbance in cardiac rhythm and a loss of consciousness, putting the athlete, as well as bystanders, at risk of injury. Central to the following discussion are the type and severity of a given congenital malformation, whether or not the patient had undergone cardiac surgery, and, if so, the type and success of the operation.

CONGENITAL HEART BLOCK

CONGENITAL HEART BLOCK. Patients with congenital complete heart block occasionally perform optimally,5 but prolonged, high-intensity isotonic exercise is ill advised, and strenuous isometric exercise is unwise, even if tolerated. If a pacemaker is required, patients are allowed isotonic or isometric exercise within the limits of sensible moderation and according to the type of pacemaker used. Contact sports risk damage to the pacemaker.

ABERRANT CORONARY ARTERY BETWEEN THE AORTA AND RIGHT VENTRICULAR OUTFLOW TRACT

ABERRANT CORONARY ARTERY BETWEEN THE AORTA AND RIGHT VENTRICULAR OUTFLOW TRACT (see Fig. 8–28 Fig. 8–28 ). This uncommon anomaly can cause angina pectoris, myocardial infarction, and sudden death.179 The risk is greatest, especially in men, when the left coronary artery arises from the right aortic sinus and passes between the aorta and right ventricular outflow tract (Fig. 30–16 Fig. 30–16 ). Sudden death typically accompanies or immediately follows relatively strenuous physical effort. Expansion of the aortic root and pulmonary trunk during exercise is believed to increase preexisting acute angulation of the proximal course of the aberrant coronary artery and to reduce its lumen, especially if the lumen is slit-like.180,181 If the coronary anomaly is identified and surgically corrected, subsequent athletic activity is not restricted, provided that flow is unobstructed and myocardial ischemia is absent.

COARCTATION OF THE AORTA

COARCTATION OF THE AORTA. In this condition the proximal aorta is less distensible than is the postcoarctation aorta, accounting, in part, for the disproportionate rise in systolic blood pressure in the proximal compartment.5 The excessive rise in systolic blood pressure during isotonic exercise represents an exaggeration of the disproportionate systolic hypertension in the resting state. A disproportionate exercise-induced postoperative rise in systolic pressure is in large part related to age at the time of repair and the adequacy of repair.

CONGENITAL AORTIC STENOSIS

CONGENITAL AORTIC STENOSIS. Unoperated patients with mild congenital aortic valve stenosis (resting gradient 20 mm Hg or less) are not restricted, provided that the electrocardiogram (ECG) is normal, the response to exercise stress testing is normal, left ventricular function is normal or supernormal, and no significant disturbances in rhythm are recorded during 24-hour ambulatory electrocardiography. Patients with moderate congenital aortic stenosis (resting gradients higher than 20 but less than 50 mm Hg), especially those at the upper range, should confine athletics to low-intensity isotonic exercise. Isometric exercise, by increasing aortic root systolic pressure, reduces the gradient, but increases an already elevated left ventricular afterload. Peak systolic gradients in excess of 50 mm Hg warn against high-intensity isotonic or isometric exercise or competitive sports.

The potential risk of sudden death is a legitimate concern when advising exercise limitations in patients with aortic stenosis. Syncope that precedes sudden death is believed to be initiated by left ventricular baroreceptors activated by an exercise-induced increase in left ventricular pressure or stretch, which causes vasodilatation in skeletal muscle followed by systemic hypotension.182 Malignant ventricular arrhythmias seldom initiate syncope but are thought to be the chief cause of death after a faint. Syncope-induced hypotension is more likely to provoke disturbances in ventricular rhythm in adults with coexisting coronary artery disease than in younger patients with normal coronary arteries and no myocardial ischemia.

After valvotomy or valvuloplasty for congenital aortic stenosis, recommendations based on the above criteria do not necessarily apply, because risk is not determined by the gradient, even when it is relatively small. Athletic activity should be limited to low or moderate intensity when left ventricular internal dimensions at end diastole are increased, when aortic regurgitation is more than mild, when the scalar ECG shows residual abnormalities of repolarization at rest or with exercise, or when important disturbances in ventricular rhythm are present at rest, with exercise, or on 24-hour ambulatory ECG. These recommendations are appropriate even if left ventricular systolic function is within normal range.

PULMONARY STENOSIS

PULMONARY STENOSIS. Patients with mild pulmonary valve stenosis (peak systolic gradient <25 mm Hg) are allowed unrestricted athletic activity. When obstruction is moderate (gradient between 25 and 50 mm Hg), high-intensity competitive sports are unwise even if tolerated, because right ventricular systolic pressure can rise appreciably. When the resting peak systolic gradient exceeds 50 mm Hg—especially if there is impaired right ventricular function—isotonic exercise should be limited to mild intensity and short duration. After successful balloon dilatation or valvotomy, patients generally need few restrictions, and, as a rule, may safely participate in high-intensity competitive athletics, provided that right ventricular size, wall thickness, and function are normal. If postinterventional obstruction to right ventricular outflow is moderate or greater, athletic activity should be limited to noncompetitive low-to-moderate–intensity exercise, especially if right ventricular internal dimensions are increased and systolic function is less than normal.

ATRIAL SEPTAL DEFECT

ATRIAL SEPTAL DEFECT. The majority of young adults with uncomplicated ostium secundum atrial septal defect are asymptomatic and often have relatively normal tolerance to exercise. High-intensity competitive sports may be tolerated but are probably unwise. When surgery abolishes the shunt in childhood or young adulthood, long-term outlook is excellent, and athletic activity is unrestricted, provided that pulmonary vascular resistance is normal, sinus node function and atrioventricular conduction are normal, and the right atrial and right ventricular volumes are normal or nearly so.

VENTRICULAR SEPTAL DEFECT

VENTRICULAR SEPTAL DEFECT. A restrictive ventricular septal defect with a functionally normal heart imposes no exercise limitations. Although patients can safely participate in competitive sports without restriction, adults in this category are uncommon. An important variation on the theme is the adult who had a moderately restrictive perimembranous ventricular septal defect that decreased in size or closed spontaneously in infancy. There is consensus that such patients are physiologically normal and should be permitted unrestricted physical activity. However, two-dimensional echocardiography with Doppler interrogation and color flow imaging should be performed to determine whether the defect closed by formation of a “septal aneurysm.”5 Although there is no evidence that strenuous athletic exercise, especially isotonic, risks rupturing a septal aneurysm, it is prudent to be aware of the morphological substrate.

After surgical closure of a moderate-to-large ventricular septal defect, recommendations regarding physical activity and competitive sports depend on the postoperative pulmonary arterial pressure; the absence of significant disturbances in ventricular rhythm during maximal exercise stress testing and during 24-hour ambulatory electrocardiography; and two-dimensional echocardiographic evidence of an intact ventricular septum together with normalization of left ventricular and left atrial size and left ventricular function. It is also desirable that the 12-lead scalar ECG exhibit little or no evidence of left ventricular volume overload or right ventricular pressure overload. If these criteria are met, patients are permitted unrestricted exercise. Persistent postoperative elevation of pulmonary arterial pressure, especially if accompanied by exercise-induced right ventricular ectopic rhythms, requires limitation to isotonic physical activity of low intensity and short duration.

Date: 2014-12-21; view: 1278