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Uncorrected Double Outlet Right Ventricle with Fallot’s physiology in pregnancy

Author Information

Madhavi J*, Panchbudhe S**, Mali K**, Satia MN***.
(Second Year Resident, Assistant Professor, Professor. Department of Obstetrics and Gynaecology, Seth G. S. Medical College and KEM Hospital, Mumbai, India.)

Abstract

The incidence of congenital heart disease in India is 8-10/1000 live births. They constitute an important cause of perinatal morbidity and mortality. Successful pregnancy outcomes with cardiac lesions in patients are in an increasing trend due to better diagnostic and available surgical correction techniques. We present a case report of a 26 year old primigravida with uncorrected Double Outlet Right Ventricle (DORV) with Ventricular Septal Defect (VSD) with pulmonary stenosis (PS) with Fallot’s physiology who underwent an emergency lower segment cesarean section and delivered a full term growth restricted baby at 37 weeks of gestation and was discharged after an uneventful postoperative course in ward.

Introduction

The incidence of Double Outlet Right Ventricle is less than 1 in 3000 live births.[1] DORV is a rare congenital cardiac lesion involving the great arteries in which both aorta and pulmonary artery arise from the right ventricle.[2] The left ventricle has no outlet or communicates to the right ventricle in the form of a VSD. In some rare cases there is no VSD, and the left ventricle is extremely hypoplastic. It is usually not an isolated cardiac malformation, but is often associated with other anatomic variations,[3] most common being DORV with subaortic VSD with PS, aorta being to the right of pulmonary trunk with Fallot’s physiology,[4] as was seen in our case. Other variations include DORV with aorta to the right and subpulmonic VSD (Taussig Bing malformation), DORV with subaortic VSD without PS. Less common variants are subaortic VSD with aorta to the left of pulmonary trunk, atrial appendages causing ambiguous atrioventricular connections. DORV is most likely the result of a malformation in the outlet portion of the embryonic ventricular loop at 3-4 weeks of gestation.[5,6] Most cases are sporadic but genetic causes have also been reported. Diagnostic test of choice is Echocardiography. Surgical correction is possible in most patients,[7] and uncorrected patients survive due to compensation by other associated lesions.

Case Report

A 26 year old primigravida, married since one year, known case of Tetrology of Fallot (TOF) with pulmonary atresia which was diagnosed at 19 years of age presented to our antenatal outpatient department for registration at 25 weeks of gestation. The patient had history of dyspnea on exertion since 19 years of age but did not consult a doctor. Her symptoms worsened and when she had dyspnea on day to day activities, she visited a cardiologist in 2012 when a 2D ECHO was done. It was suggestive of  subaortic ventricular septal defect(VSD) with aortic overriding with valvular infundibular pulmonary stenosis (PS) with absent left pulmonary artery and aortic root dilatation suggestive of Tetrology of Fallot. Significant aortopulmonary collaterals were also present, with fair biventricular function. She was started on tablet propranolol 10 mg 2-1-2 and had regular follow up in cardiology outpatient department (OPD). She visited our antenatal OPD at 25 weeks of gestation and was admitted for further evaluation and management. On admission, her general condition was fair, pulse rate 82/min, blood pressure 100/60 mm Hg, grade II clubbing present in both hands and feet with peripheral cyanosis. Cardiovascular system examination revealed loud ejection systolic murmur in aortic area with single 2nd heart sound, no jugular venous pulsations. Respiratory and central nervous system examination was normal. Obstetric examination revealed uterus corresponding to 24 weeks size with fetal heart sounds present. All routine investigations were sent. Her hemoglobin was 15.8 g/dl and hematocrit was 42.6%. Elecrocardiography revealed right axis deviation. Cardiology reference was taken. 2D ECHO was done, which was suggestive of large sized nonrestrictive malaligned, subaortic VSD with bidirectional shunt, severe valvular  pulmonary stenosis with gradient of 64 mm of mercury across the pulmonary valve, aorta being to the right of pulmonary artery and with good biventricular function suggestive of congenital heart disease with Double Outlet Right Ventricle with TOF physiology. The patient was advised to continue tablet propranolol 10 mg 2-1-2. Her serum TSH was 6.44 microunits/ml, endocrine reference taken and patient was started on tablet thyronorm 50 μg once daily. Obstetric ultrasonography, fetal 2D ECHO and anomaly scan were normal. She was discharged after 10 days and was advised regular follow up in antenatal and cardiology OPD. Obstetric Doppler was done at 28 weeks which was normal. She was lost to follow up and presented to antenatal OPD at 37.2 weeks of gestation with a history of decreased fetal movements since one day. Obstetric examination revealed uterus corresponding to 32-34 weeks with clinically severe oligohydromnios. Ultrasonography for amniotic fluid index was done, which was 4.1.  Non stress test was done which was non reactive. Decision of emergency lower segment cesarean section was given in view of fetal distress. Hence, an urgent Cardiology opinion was taken regarding fitness for the same which was given with high cardiac risk. Patient was taken up for emergency lower segment cesarean section in view of fetal distress. Infective endocarditis prophylaxis was given. Spo2 was 84%. Epidural anaesthesia with 3 ml of 2% xylocaine, 6 ml of 0.375% bupivacaine, 4 ml of 0.25% bupivacaine and 2 ml of 0.5% bupivacaine and injection Fentanyl 50 μg was given, these doses being given at an interval of 10-15 min via epidural catheter. She delivered a female child of 1.390 kg. She tolerated the procedure and anesthesia well. Post operatively cardiology reference was taken. She was advised to continue tablet propranolol 10 mg 2-1-2 and to follow up in cardiology OPD after six weeks for corrective surgery. The baby was transferred to neonatal intensive care unit in view of severe intrauterine growth restriction and very low birth weight. Patient and baby were discharged on Day 15 of surgery.

Discussion

Maternal heart disease complicates 0.2 to 3% of pregnancies, and congenital heart lesions now constitute at least half of all these cases.[8] Tetrology of Fallot is the most common cyanotic congenital heart disease. It is a tetrad of lesions that includes overriding of aorta, a large malaligned ventricular septal defect, infundibular pulmonic stenosis and right ventricular hypertrophy. Lesions with a large ventricular septal defect (or single ventricle) and severe pulmonary stenosis so that there is right to left shunt across the VSD and low pulmonary blood flow due to the pulmonary stenosis are classified as Fallot’s physiology. Our patient with DORV with VSD with PS also had Fallot’s physiology. The clinical picture is indistinguishable from classic Tetrology of Fallot. Patients usually present with dyspnea, difficulty in weight gain, cyanosis, a murmur due to pulmonary stenosis (systolic ejection murmur), from the VSD (regurgitant murmur), or both. In moderate to severe PS, cyanosis is prominent due to decreased pulmonary blood flow, thus resembling TOF. If uncorrected, cyanosis leads to polycythemia and digital clubbing. Cyanosis is due to three separate mechanisms which include inadequate pulmonary blood flow, right to left shunting or intrinsic pulmonary disease. In TOF and Fallot’s physiology, cyanosis results from a right-to-left shunt at the level of ventricles and inadequate pulmonary blood flow. The outflow obstruction causes the blood ejected from the right ventricle to cross the VSD and enter the aorta that arises from the same ventricle. This reduces the amount of pulmonary blood flow available for oxygenation and adds desaturated blood to the systemic circulation, leading to near equalization of the right ventricle and the systemic pressure.[9] Chronic hypoxemia in these patients leads to polycythemia, increased blood viscosity, risk of thromboembolic episodes, vasodilatation, hyperventilation and chronic respiratory alkalosis. These adaptive mechanisms limit cardiac reserve and oxygen delivery during stress conditions such as labor.[10] Hence, cyanotic heart disease leads to decreased fertility and fetal loss, as cyanosis worsens in pregnancy with decreasing peripheral vascular resistance.
Antenatal complications include spontaneous abortions, stillbirths, preterm births, intra uterine growth restriction and infective endocarditis. The most important risk factor for adverse fetal outcome in cyanotic patients is the degree of cyanosis. An arterial oxygen saturation >85% and a hemoglobin concentration <18 g/dl would more likely result in live birth as was seen in our case, whereas hemoglobin concentrations >20 g/dl is associated with poor foetal prognosis.[11] A hematocrit above 65% is almost completely associated with fetal loss.[12] The principle danger in a pregnant woman with Fallot’s physiology is cardiac decompensation due to additional demands imposed by the physiological changes of pregnancy and parturition. The chances of a good outcome depend on cardiac capacity, correction prior to pregnancy and associated cardiac lesions. In our case, the patient had an uncorrected disease. A multidisciplinary approach in a tertiary centre is more important as hypotension and volume overload state during labor and puerperium are poorly tolerated.  Hypotension and decreased peripheral vascular resistance during late pregnancy and puerperium lead to an increase in right to left shunt and further cyanosis. Anesthesia carries considerable risk in Fallot’s patients and accordingly the management is based on avoiding changes that would increase the magnitude of right to left shunt, avoiding dehydration at the same time to prevent further blood viscosity.[13] Hence, Epidural analgesia was given in our case. Medical management throughout pregnancy includes drugs to increase peripheral vascular resistance - propranolol as was given in this case. Surgical strategy depends on the relation of VSD to the great vessels and distribution of coronary arteries. A biventricular repair is done with creation of an intracardiac tunnel to connect the left ventricle to the aorta and creation of an intracardiac or an extracardiac route to connect the right ventricle to the main pulmonary artery.[14]  Timing for this surgery depends on the size and clinical condition of the patient, but it is generally completed by the age 4-6 months. This was a case of uncorrected DORV with Fallot’s physiology whose antepartum and postpartum course was uneventful due to multidisciplinary approach involving an obstetrician, cardiologist and anesthesiologist at a tertiary care centre.

References
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Citation

Madhavi, Panchbudhe S, Mali K, Satia MN. Uncorrected Double Outlet Right Ventricle with Fallot’s physiology in pregnancy. JPGO 2015. Volume 2 No. 6. Available from: http://www.jpgo.org/2015/06/uncorrected-double-outlet-right.html