Essay: Cardiac disease and pregnancy

Pregnancy imposes unique physiological strains on the cardiovascular system which are magnified in presence of heart diseases. Maintaining maternal cardiovascular stability with adequate placental perfusion can be challenging. Many mothers are asymptomatic and the physiological changes of pregnancy may precipitate decompensation. The risk and the preferred anesthetic techniques differ amongst the various cardiac conditions. Goal of anesthetic management is to maintain hemodynamic parameters within a narrow therapeutic range. The risk in mother and fetus doubles increasing the peripartum morbidity and mortality. Thus multidisciplinary planning should be at the helm of pre, peri and post partum management.1
INTRODUCTION
Cardiac disease in pregnancy accounts for 0.1-4% in the developed nations of which 70-80% are patients with congenital heart disease who survive to adulthood because of better surgical techniques and newer and better drugs. As women present at a much advanced age in recent times ischemic heart disease also may complicate pregnancies .1 There is usually deterioration by 1 grade (NYHA class) during pregnancy in patients with pre existing cardiac disease.1 (Table 1)
While assessing a pregnant patient certain warning signs may point to a cardiac pathology in an otherwise unsuspected case.
• A rising pulse rate may be a harbinger of cardiac decompensation. The radial pulse is difficult to detect when the heart rate is fast or irregular. Hence auscultating the heart with a stethoscope is more prudent and accurate.
• The blood pressure (BP) should be recorded with the woman sitting comfortably with a manual sphygmomanometer with an appropriate sized cuff. The arm should be at an angle and supported to ensure that the cuff is at the level of the left atrium.
• Crackles may sometimes develop in late pregnancy due to the splinting effect of the enlarged uterus resulting in poor lung expansion. These crackles disappear on asking the woman to take several deep breaths and then cough several times. Crackles posteriorly in the lung bases may be pathognomic of incipient cardiac failure.1
The risk and the preferred anesthetic techniques differ amongst the various cardiac conditions which are enumerated below. (Table 2) The FDA classifies drug risk during pregnancy based on available data (Table 3).
The various cardiac conditions complicating pregnancy and their management are discussed below.
17.1 CONGENITAL HEART DISEASE
Grown up with Congenital Heart Disease (GUCH) is now becoming the most common cardiac disease in pregnant patients as due to improved medical and surgical management as many congenital heart disease (CHD) patients reach childbearing age.2 Maternal and fetal mortality varies depending upon the lesion associated. If complete repair and normal cardiovascular function is achieved by successful surgery during childhood then patients often require no special management except antibiotic prophylaxis as per the current recommendations. Some patients present during pregnancy with uncorrected lesion or partially corrected lesion, which may decompensate during the course of pregnancy and labor and their management is a challenge.2 -4
Major categories of CHD are
• Left to right shunts which includes atrial septal defect (ASD), patent ductus arteriosus (PDA), ventricular septal defect (VSD).
• Right to left shunts includes tetralogy of fallots (TOF), Eisenmenger’s syndrome.
• Congenital valvular and vascular lesions- aortic stenosis, pulmonary stenosis and coarctation of aorta
In these entire lesion the anesthetic goal should include antibiotic prophylaxis, avoid factors which can cause reversal of shunts such as hypoxia and hypercarbia.
Left-to-Right Shunts
Either small ASD, VSD or PDA with modest left to right shunt without pulmonary hypertension is often well tolerated during pregnancy. However mortality is high with coexisting pulmonary hypertension. Physiological changes during pregnancy may increase left-to-right shunt and worsen the degree of pulmonary hypertension. There may be increased risk of preeclampsia and small for gestational age babies in case of unrepaired lesions. 2-4
There is increased incidence of Supraventricular arrhythmias (Atrial fibrillation and flutter) due to
• Chamber enlargement
• Pulmonary hypertension (PH)
Paradoxical embolus is common during pregnancy as
• Respiratory efforts may increase due to physiological changes in pregnancy
• Straining during parturition
Management of ASD in a woman of childbearing age
Anesthesia Management:
The major goal in peripartum management is maintenance of systemic vascular resistance (SVR) and pulmonary vascular resistance (PVR) ratio as alteration in them may lead to ventricular failure, shunt reversal and hypoxia. 5 Continuous monitoring (standard monitoring plus trans-esophageal echocardiography [TEE] if available) and supplemental oxygen therapy is essential.6 Accidental intravenous infusion of air bubbles should be avoided.
Early lumbar epidural analgesia for labor and vaginal delivery is desirable to avoid pain and resulting increase in SVR. 5 For caesarean section slow graded segmental epidural anesthesia is preferred. During epidural space localization loss of resistance to saline is preferable than air as identification of the epidural space with air might result in systemic air embolization especially in pregnancy due to high epidural venous pressure and engorged veins. General anesthesia is also well tolerated and combined opioid and inhalation technique is preferred. 5-7 Oxytocin is used to induce uterine contractions and reduce bleeding following delivery of the baby. This should be given as slow intravenous infusion and not as a bolus.
Presence of isolated ventricular septal defects (VSD) possesses a low risk during pregnancy. However when complicated by pulmonary hypertension and or Eisenmengerisation there is a high risk of cardiac complications. If the VSD has been repaired prior to the development of pulmonary hypertension risk is minimal.
General precautions during transcatheter closure of ASD during pregnancy
• Should be performed during second trimester
• Long venous sheath to reduce radiation dose to pelvic area
• Intracardiac echocardiography for balloon sizing and deployment of device reduces radiation dose
Key points
• Avoid accidental injection of air
• Treat arrhythmia promptly
• Infective endocarditis prophylaxis
Right-to-Left Shunts
Eisenmenger’s Syndrome – Uncorrected left to right shunt (ASD, VSD or PDA) may result in right ventricular hypertrophy, elevated pulmonary artery pressure and eventually right ventricular dysfunction. The conglomeration of these signs and symptoms are known as Eisenmenger’s Syndrome. After irreversible pulmonary hypertension occurs, correction of primary lesion does not help. Patients with Eisenmenger’s syndrome who become pregnant should be consulted to terminate pregnancy as there are chances of sudden profound hypoxemia and death. Maternal mortality is as high as 30-50 % in these patients.2, 7
Management includes early hospitalization, continuous oxygen administration, pulmonary vasodilators and prophylactic anticoagulation. Patient may however not respond to above treatment and pregnancy may be fatal. [21]
Anesthetic management
Supplemental oxygen must be provided to combat the hypoxia and prevent further increase in PA pressures. Continuous monitoring including central venous and intra arterial catheter facilitates rapid detection of sudden changes in hemodynamics and cardiac filling pressures. However a pulmonary artery catheter is relatively contraindicated as it is difficult to position and carries the risk of pulmonary artery rupture. Trans-esophageal echocardiography (TEE) is preferred.
For labor analgesia, as anticoagulation may contraindicate regional techniques, intravenous remifentanil infusion or patient controlled analgesia (PCA) may be the modalities of choice.8, 9 If not contraindicated epidural or intrathecal opioid or cautious segmental epidural analgesia provided the SVR is maintained, can be considered. 8 For emergency caesarean section general anesthesia is the anesthesia of choice .However few authors mention use of slow onset epidural anesthesia for elective caesarean .9 It is essential to maintain preload, SVR and oxygen saturation. To maintain adequate venous return avoid aorto-caval compression and judicious intravenous crystalloids and small doses of phenylephrine are considered.
Regardless of the anesthetic technique, many life-threatening complications may occur in the postpartum period mainly hypoxemia, cardiac dysrhythmias, and thromboembolic events . Hence continued use of invasive monitoring, oxygen, inhaled nitric oxide and extreme vigilance is recommended in the peripartum period. 7, 9
Key Point
• Maintain in SVR : PVR ratio
• Prevent hypoxia, hypercapnia, acidosis
Tetralogy of Fallot (TOF)
It is the most common right-to-left shunt lesion in women of childbearing age. Four components of TOF include VSD, overriding of aorta, infundibular or right ventricular outflow tract obstruction, and right ventricular hypertrophy. Presence of cyanosis, history of syncope, polycythemia (hematocrit > 60), decreased arterial oxygen saturation (<80%), right ventricular hypertension, and congestive heart failure indicates poor prognosis .2,10 Goals of management should include • Avoid decrease in SVR • Maintain adequate intravascular volume and venous return • Avoid myocardial depressants • Infective endocarditis prophylaxis For labor analgesia and vaginal delivery in these patients systemic or intrathecal opioids, or pudendal block may be considered. Segmental epidural analgesia is not recommended because of chances of decrease in SVR. For forceps-assisted deliveries low dose ketamine may be considered. Anesthesia of choice for caesarean section is general anesthesia with invasive monitoring and TEE. Patients with corrected TOF, even if asymptomatic, 2 D echocardiography is must along with 12 lead electrocardiogram (ECG) as they may have residual lesions and atrial and ventricular arrhythmias due to surgical injury to the cardiac conduction system. 11 Management of TOF in a woman of childbearing age is as follows: Key points • Regional anesthesia may lead to worsening of right to left shunt and should be avoided • In corrected TOFs, RV and RVOT should be assessed 17.2 PRIMARY PULMONARY HYPERTENSION It is a rare disease entity affecting young women of child bearing age with very high mortality reaching nearly 30%. 12 There is reduction in vascular nitric oxide and prostacyclin synthesis. At the same time there is increase in endothelin and thromaboxane production . The pulmonary artery pressure (PAP) is raised above 25 mmHg at rest without any obvious cause. Pregnancy should be avoided as far as possible. However use of oral contraceptives in unadvisable as they are known to accelerate the progression of the disease. 13 Management Any factors which increase the pulmonary vascular resistance (PVR) should be avoided such as hypoxia, hypercarbia and acidosis. Avoidance of myocardial depression and aortocaval compression and maintenance of SVR , intravascular volume and venous return should be the goal. Anticoagulation is a must in any patient with primary pulmonary hypertension. As Warfarin is known to be teratogenic ,subcutaneous Enoxaparin (1 mg/kg twice daily) is recommended.13 Oxygen to counter the hypoxia and diuretics for right heart failure should be administered. IV epoprostenol should be administered by continuous infusion as it has a very short half life of less than 6 minutes and can cause rebound increase in pressures if abruptly discontinued. Endothelin receptor antagonists are contraindicated .Calcium channel blockers are not favoured because of their negative inotropic effects.12 Timing of delivery: The delivery should ideally be carried out between 32 to 34 weeks . 14 Vaginal delivery using low dose epidural analgesia would be the safest mode. If elective caesarean section is planned single shot spinal anesthesia should be avoided as the RV may not be able to respond to deceased venous return. In fact it is prudent to avoid regional anesthesia in any form. Vasopressors are to avoided as they increase the pulmonary artery pressure. Stress associated with laryngoscopy and intubation may also increase the PVR.6 Careful titration of oxytocin is required as it may decrease the SVR. Carboprost should be avoided because of its pulmonary side effects and methergin should be avoided as it causes vasoconstriction. Fluid management in these patients is challenging as neither hypovolemia nor hypervolemia are tolerated. Fluid should be administered monitoring the central venous pressure or echocardiography. Right ventricular diastolic dysfunction is best treated with diuretics or haemofiltration.12 Inotropic agents may be required for systolic failure of the RV. Dobutamine at doses less than 10µk/kg/min decreases the pulmonary vascular resistance but at higher doses may have a detrimental effect on vasculature. Dopamine is avoided for its propensity of causing tachyarrhythmias. Phosphodiesterase inhibitors like milrinone have been known to reduce the pulmonary vascular resistance. Nebulised milrinone has the advantage of direct effect on pulmonary vasculature with less incidence of systemic hypotension.12 Vasopressors like norepinephrine may be used to maintain the systemic vascular resistance above the pulmonary vascular resistance. However their effect is offset by the rise in pulmonary vascular pressure which may result in RV failure. Also the effect of α adrenergic agents on the α receptors of the uterus may result in reduced uterine blood flow.12 Patients should be monitored in high dependency units for 72 hours post partum as the fluid shifts associated with delivery may decompensate the right ventricle. Key points: • Factors which increase pulmonary artery pressures must be avoided • Pulmonary vasodilators and oxygen form the mainstay of therapy • Anticoagulation is must • Regional anesthesia should be avoided as decrease in systemic vascular resistance may result in RV ischemia • Inotropic agents which do not increase the PVR should be used 17.3 HYPERTROPHIC OBSTRUCTIVE CARDIOMYOPATHY (HOCM) It is a genetically transmitted cardiac disease characterised by left ventricular hypertrophy. There is reduced left ventricular size and compliance. Chest pain , dyspnoea and palpitations which may be confused with normal symptoms of pregnancy are the hallmark of HOCM Any reduction in the preload or the afterload can result in increased outflow gradient and decreased left ventricular filling. Thus regional anesthesia is relatively contraindicated in these patients. Invasive monitoring is indicated and any hypotension should be promptly treated with fluids and phenylephrine. Since it is a pure α agonist it does not have a positive inotropic effect and at the same time it slows the heart which may be advantageous for the perfusion of the hypertrophied ventricle. The morbidity directly correlates with the preconception NYHA status of the patient. 15 Tachyarrhythmias including atrial fibrillation should be aggressively treated.2 Beta blockers should be continued throughout the pregnancy. In patients with history of syncope an automatic implantable cardiac defibrillator (AICD) should be implanted preconception. Key points • Chest pain , dyspnoea and palpitations are the hallmark of HOCM • Phenylephrine and beta blockers are the drugs of choice • Adequate intravascular volume, maintain SVR and avoiding increase in myocardial contractility and pulse rate are the goals in anesthesia management 17.4 ISCHEMIC HEART DISEASE It is uncommon in pregnancy with an incidence of 1 in 10000 pregnancies. Myocardial infarction can commonly occur in third trimester or in the puerperium of the first or second pregnancies. The mortality may be very high up to 45% if myocardial infarct occurs within 2 weeks postpartum. The presenting symptoms are usually ischemic chest pain , with ECG abnormalities and elevated cardiac troponin I levels ( > 0.15 ng/ml ). Creatinine kinase levels may increase during normal labour and is not a sensitive indicator . In 78% of the women there is no predisposing cause. However increasing maternal age , smoking amongst young women and prevalence of type 2 diabetes mellitus may be some of the contributory causes.
Differential diagnosis are pre-eclampsia, acute pulmonary embolism , sickle crisis haemorrhage and aortic dissection
Management consists of early coronary angiography as spontaneous coronary dissection is the most common cause. 84% of the lesions involve left anterior descending artery. Coronary stenting or coronary artery bypass grafting may be the treatment options. Thrombolysis using tissue plasminogen activator (TPA) 100mg over 90minuts may be used. However its use in early post partum period is contraindicated due to the risk of haemorrhage.
Intramuscular or intravenous ergometrine may be associated with myocardial infarction due to coronary artery spasm. It would be best to avoid ergometrine in patients at risk of ischemic heart disease and to use it intramuscularly or small incremental intravenous doses if required in high risk patients. Ergometrine acts rapidly with 2 minutes of intravenous administration. Glyceryl trinitrate 10 -400 mg/min injected immediately intravenously or sublingually 300mg may be used to prevent infarct if coronary artery spasm is suspected. If this is not effective immediate coronary angiography and intracoronary injection of GTN or aspiration of thrombus may be undertaken.
Another rare cause of myocardial infarction is the use of nifedipine for the treatment of preterm labour where the cause may be either hypotension or reflex tachycardia associated with it.15
Differential diagnosis are pre-eclampsia, acute pulmonary embolism, sickle crisis haemorrhage and aortic dissection. Diagnosis can be confirmed by ischemic chest pain, with ECG abnormalities and elevated cardiac Troponin I levels ( > 0.15 ng/ml ).
Key points
• Ergometrine to be avoided if there is risk of myocardial ischemia
• Early thrombolysis
• Coronary stenting or coronary artery bypass grafting may be the treatment options
17.5 VALVULAR DISORDERS
Valvular heart diseases are most frequently encountered in pregnant women in developing nations. Many of these women are asymptomatic and the physiological changes of pregnancy may precipitate failure. Rheumatic mitral stenosis is the most commonly encountered valvular lesion during pregnancy. Complications during pregnancy include failure, atrial dysrhythmias, systemic or pulmonary embolism, and infective endocarditis. Regurgitant lesions are well tolerated during pregnancy due to physiological changes of pregnancy, however stenotic lesions are poorly tolerated due to the risk of failure and pulmonary edema.16
Goal of anesthetic management is to maintain hemodynamic parameters within a narrow therapeutic range. Patients with symptomatic disease warrant invasive monitoring.
The incidence of complications is greater in
1. Patients with prior history of arrhytmias, heart failure, transient ischemic attacks or stroke
2. If the baseline NYHA class is III or more or presence of cyanosis.
3. Ejection fraction less than 40%
4. Pulmonary artery pressure 50% of systemic pressure
5. Patients with aortic or mitral regurgitation who have NYHA class III or IV symptoms
Mitral stenosis (MS)
The normal area of the mitral valve is 4-6 cm2. The symptoms of MS begin to appear when the valve area is reduced to less than 2 cm2. As a result of MS the filling of the left ventricle from the left atrium is hindered. This results in decreased stroke volume and cardiac output. A state of fixed cardiac output ensues and it is difficult for the heart to meet the increased cardiac output demanded by the pregnant state. 17
The increased heart rate in pregnancy limits the time for diastolic filling with the resulting increased left atrial pressure and the propensity for pulmonary edema. Thus there is a downhill course and the patients NYHA status usually worsens by one grade. The situation becomes further grim with the onset of atrial fibrillation and there is 80% incidence in systemic emboli in these patients.
There is a sudden increase in preload due to autotransfusion immediately after delivery and there is high incidence of pulmonary edema and death which can occur in the immediate peripartum and postpartum period and require close monitoring.
Medical management
Bed rest, oxygen therapy and diuretics form the basis of therapy. Beta blockers can be used to reduce the heart rate. They reduce the incidence of maternal cardiac failure without adverse effects on the fetus. Recent evidence does not show any beneficial role of digoxin in treatment of cardiac failure. If there is atrial fibrillation then aggressive treatment with digoxin, beta blockers and anticoagulation is required. Anticoagulation has proven to be beneficial even in the absence of atrial fibrillation.
The standard guidelines for anticoagulation during pregnancy are:
• Up to 12 weeks antepartum SC/IV heparin (aPTT 1.5-2.5 times the normal)
• Between 12-36 weeks warfarin ( INR 2.5-3.0)
• After 36 weeks SC/IV heparin
Unfractionated heparin has been replaced by low molecular weight heparin. When anticoagulation is necessary, especially in women with mechanical valves, warfarin or low-molecular-weight heparin should be replaced by unfractionated heparin 36 h before induction of labour. Unfractionated heparin should be discontinued 4—6 h before delivery and restarted 4—6 h after delivery. Antibiotic prophylaxis for bacterial endocarditis is reserved for those patients who have previous history of endocarditis or in presence of infection.
Surgical Management
Mitral commissurotomy is preferred if mitral stenosis is diagnosed prior to pregnancy
Percutaneous valvuloplasty is the treatment of choice during the second trimester in pregnant women. After valvulopasty the valve area increases to 1.5cm2 with a 100% success rate. Foetal loss is high in open commissurotomy though maternal outcome is same for both the procedures. In severe cases where there is a calcified valve or thrombus, valve replacement may be indicated. In open valve replacement there are high chances of losing the fetus 16-33%. Maternal mortality may be also as high as 1.5 -5%.18, 19
Anesthesia management
For vaginal delivery, labour analgesia is a must as it attenuates pain and associated sympathetic response which might precipitate failure. Segmental lumbar epidural analgesia is gold standard.
For caesarean section plain epidural or combined spinal epidural (CSE) techniques are preferred as it produces controlled hemodynamics. Spinal anesthesia is contraindicated as sympathetic blockade produced by single shot can lead to cardiovascular collapse in severe MS. 14 However general anesthesia is the method of choice in cases of decompensated heart failure, obstetric emergency or when patient is on anticoagulation. Avoiding tachycardia, hypotension and judicious fluid management along with ICU care in postoperative period is the key to management.
Mitral Insufficiency/ regurgitation (MR)
Mitral valve regurgitation is the second commonest valvular lesion in pregnancy. Though most patients with MR tolerate pregnancy well some present with atrial fibrillation, bacterial endocarditis, systemic embolization, and pulmonary edema during late pregnancy. However if associated with coexisting MS morbidity and mortality increases significantly.18 Congenital mitral valve prolapse (MVP) is well-tolerated during pregnancy and therapeutic interventions are thus rarely necessary.18,20
In MR, regurgitation through an incompetent mitral valve results in chronic volume overload of the left atrium and dilatation with resultant pulmonary venous congestion. Physiologic decrease in SVR improves forward flow. However increases in SVR due to sympathetic stimulation during labor pain, uterine contractions, or surgical stimulation, may lead to acute left ventricular failure.
Anesthetic management
Adequate analgesia for labor will decrease peripheral vasoconstriction and thus attenuate the increase in left ventricular afterload and forward flow. Segmental lumbar epidural analgesia is the preferred technique. Controlled sympathetic blockade which decrease SVR and is beneficial. However to augment preload adequate intravenous fluid infusion to maintain left ventricular filling volume is must.
For caesarean section plain epidural or combined spinal epidural (CSE) technique can be considered. Graded epidural supplementation produces minimal sympathetic blockade and hemodynamic changes with the advantage of better pain relief in the post operative period.
Keypoints MS MR
Prevent Tachycardia
Avoid fluid overload
Avoid Decrease in SVR and increase in PVR Maintain sinus rhythm
Prevent Bradycardia
Avoid increase in SVR
Avoid myocardial depression
Maintain sinus rhythm
Aortic stenosis and regurgitation (AS, AR)
Rheumatic mitral stenosis is the most commonly encountered valvular lesion during pregnancy, but aortic valvular involvement has greater functional significance. Mild to moderate aortic stenosis during pregnancy can rapidly deteriorate the hemodynamics and precipitate congestive heart failure, carrying a high risk of maternal and foetal mortality.
Bicuspid aortic valve is the most common congenital cardiac malformation occurring in 1 – 2% of the population.18 It can present either as a regurgitant or stenotic pathology. Calcification of the bicuspid aortic valve occurs at an early age due to degeneration caused by mechanical strains on the valve. 21 However it is a rare entity in child bearing age. Regurgitant valvular lesions are well tolerated during pregnancy, whereas stenotic lesions have a greater potential for decompensation and left ventricular failure. 22, 23 There is a higher incidence of preterm birth (44%), intrauterine growth retardation (22%), and lower birth weight in these patients. 19, 20
Anesthesia goals in aortic stenosis include maintenance of intravascular volume and preload, avoiding aorto-caval compression, cardiac arrhythmias and myocardial ischaemia. Regional and general anesthesia have been used successfully. General anesthesia in patients with stenotic valvular heart diseases should be induced with high dose opioid technique, which is detrimental for the fetus. Volatile agents also have a depressant effect on the fetus. However general anesthesia is the method of choice in emergency or when anticoagulation has been instituted or in case of decompensated heart failure.
Profound sympathetic blockade produced by single shot spinal anesthesia can lead to cardiovascular collapse and is contraindicated in severe aortic stenosis. 14 In the immediate postpartum period cardiac output and stroke volume increases by 80% due to autotransfusion and relief of venacaval compression. 24 To counteract this, induced controlled diuresis with furosemide should be considered. Major cause of post partum haemorrhage is uterine atony, the primary treatment of which is a titrated infusion of uterotonic drugs. Rapid infusion of IV oxytocin (>5U over 5mins) can cause hypotension, tachycardia and fluid retention leading to heart failure. 25 Hence oxytocin should be used slowly (an infusion pump is preferred over drip) with vigilance.
The argument of general versus regional anesthesia for complex valvular diseases in pregnancy is still inconclusive and is based on anecdotal case reports and theoretical risks. Repeated reassessments of the cardiovascular system should dictate the management. Anesthetic plan for delivery should include use of invasive monitoring throughout labor and delivery, with provision of high-dependency postpartum care. Multidisciplinary and comprehensive antenatal care of these patients is essential and should involve the anesthesiologist, obstetrician and cardiologist.
Keypoint
Single shot spinal anesthesia is contraindicated in severe aortic stenosis
Keypoints AS AR
Avoid decrease in SVR
Avoid Bradycardia
Maintain preload and ventricular filling Avoid marked increase in SVR
Avoid Bradycardia
Avoid myocardial depression
17.6 PERIPARTUM CARDIOMYOPATHY (PPCM)
This entity may present in late pregnancy or in early puerperium. However it has also been known to occur up to as late as five months post partum. There should be a high index of suspicion in pregnant or a puerperal woman who complain of increasing shortness of breath especially on lying flat or at night. There may be confusion with preeclampsia as 25% of the females may be hypertensive. 26 The incidence ranges from 1:1500 to 1:4000 live births and the mortality may reach as high as 18- 56% 1
The exact etiology is not known. However viral, autoimmune and idiopathic have all been implicated. Predisposing factors include advanced maternal age, multiple gestations, associated preeclampsia, prolonged tocolysis, multiparity, diabetes, obesity and Afro- Caribbean descent. 1, 27, 28An urgent electrocardiogram (ECG) , Echocardiogram (Echo) and X ray chest is volunteered in all these patients.26 PPCM is an entity which is diagnosed mainly by exclusion.
Terbutaline when used for prolonged tocolysis has been implicated as one of the causative factors. However it is still unknown whether β agonist therapy is a causative agent or it simply unmasks a clinically silent heart disease.15
Conditions which may mimic PPCM and a high degree of suspicion are required in diagnosis include myocardial infarction , severe pre eclampsia, sepsis, pulmonary thromboembolism and amniotic fluid embolism. 15
The criteria for PPCM were first put forth by Demakis in the year 1971 27
• Absence of any heart disease before the last month of pregnancy
• No known etiology
• Heart failure in the last month of pregnancy or the one which may develop within the first five months in the post partum period.
To this the echocardiographic evidence has also been added which include 27
• Ejection fraction < 45% • Left ventricular end diastolic dimensions > 2.7 cm/m 2
• Fractional shortening < 30%
Electrocardiography
• Normal sinus rhythm , sinus tachycardia or dysrhythmias may be present
• Other changes which may include left ventricular hypertrophy, inverted T waves, non specific ST changes and Q waves may be present.
Xray chest usually shows cardiomegaly. Thus diagnosis lays mainly on echocardiographic findings and there should be a low threshold for taking the patient for echocardiography.
In cases where diagnosis is unclear an endomyocardial biopsy if performed will show myocarditis in 76% of the patients.15
Treatment includes supportive management. Symptoms may improve significantly with the delivery of the fetus. Salt restriction and diuretics to decrease the pulmonary congestion and volume overload are recommended. Vasodilators are needed to decrease the afterload in patients with systolic dysfunction. Because of risk of teratoginicity , neonatal anuric renal failure and even neonatal death the use of angiotensin converting enzyme inhibitors are contraindicates in pregnancy. Hydralazine in addition to amlodipine or nitrate is the drug of choice. Angiotensin converting enzyme inhibitors are the drug of choice in the postpartum period even in breast feeding mothers. Carvedilol , a beta blocker improves survival in PPCM. Other newer modalities of treatment include immunosuppressive therapy and use of pooled polyclonal human antibodies .
Digoxin is used to treat atrial arrhythmias. It also has positive inotropic effect. Amiodarone is avoided as it may result in fetal hypothyroidism and premature delivery. Fetal bradycardia, hypotension and heart blocks may be some of the side effects of verapamil . Anticoagulation is necessary in patients with poor cardiac function (EF< 35%) as there is a risk of thromboembolism in these patients. Unfractionated or low molecular weight heparin may be used. 1,15
Anesthetic management: The best option is vaginal delivery with low dose epidural analgesia. Blood pressure and fluid status need vigilant monitoring. General anesthesia with invasive monitoring should be provided for caesarean sections
Key Points
• Echocardiography with EF< 45% is diagnostic
• Diuretics to decrease pulmonary congestion and vasodilators like hydralazine, amlodipine and nitrates are the treatment of choice.