Harsha A*, Pardeshi S**, Gupta AS***.
(* Second Year Resident, ** Assistant Professor, *** Professor. Department of Obstetrics and Gynecology, Seth GS Medical College and KEM Hospital, Mumbai, India.)
Rheumatic mitral stenosis constitutes a major cause of acquired heart disease complicating pregnancy in India. Here, a rare case of a pregnant woman undergoing balloon mitral valvuloplasty, for severe mitral stenosis, leading to rupture of mitral valve leaflet and eventually surviving mitral valve replacement is being discussed, she could continue the pregnancy till term and had an elective cesarean section.
Heart disease complicates nearly 1% of all pregnancies and now is one of the leading causes of indirect maternal mortality. In presence of maternal heart disease, the circulatory changes may lead to death of the mother or the fetus, cardiac failure being most common cause of maternal mortality in such cases. Rheumatic heart disease is the most common heart disease in pregnancy and otherwise in developing counties.
A 27 years old female, married since 9 years, with previous lower segment cesarean section (for meconium stained amniotic fluid), at 25 weeks and 3 days of gestation with critical mitral valve stenosis came to emergency with complaints of grade 4 breathlessness. On examination, pulse rate was 100 per minute, blood pressure was recorded to be 90/70 mm of Hg. In cardiovascular system examination, first and second heart sounds were heard normally along with a mid diastolic murmur and pansystolic murmur. All lung fields were clear and air entry was bilaterally equal on respiratory system examination. She was a diagnosed case of rheumatic heart disease, having severe mitral valve stenosis (MS), with severe mitral valve regurgitation (MR), moderate tricuspid valve regurgitation (TR), and severe pulmonary hypertension (PH), diagnosed during her previous pregnancy, 8 years back. She was admitted, 2-D echocardiography was done. The ejection fraction was 60%, mitral valve area was 0.7/0.8 mm2 , it showed severe MR (central jet), severe MS, severe TR and severe PH. She was stabilized and started on antidiuretics. She underwent balloon mitral valvuloplasty, during which she sustained left commissural and anterior leaflet rupture, she became unstable, and an emergency mitral valve replacement (MVR) had to be done for her. Native mitral valve was excised, MVR was done using Sorin 25 mm mechanical valve following which she was kept under observation in cardiac ICU for 5 days on ventilator support. She was put on digoxin, frusemide, spironolactone and aspirin. For anticoagulation, she was put on warfarin 5 mg OD and 7.5 mg on two days in a week. She got discharged against medical advice on day 6 of the surgery. She followed up in antenatal OPD fortnightly. In her routine antenatal investigations, fasting blood sugar was 67 mg/dl, and postprandial blood sugar was 104 mg/dl. Her TSH level was 1.52 IU/L. She tested negative for HIV, HBsAg, HCV and VDRL. She received 2 doses of tetanus toxoid. In the malformation scan however, hydrocephalus (isolated) with involvement of the lateral ventricles was identified in the fetus along with a raised amniotic fluid index of 37 cm.
Later she got readmitted at 35 weeks of gestation in preterm labor. Oral warfarin was replaced with intravenous heparin in the dose of 5000 IU qid. APTT was monitored, maintained between 2 to 3 by titrating the dose of heparin to up to 7500 IU qid.
She had polyhydramnios and fetal anomaly scan showed isolated hydrocephalus. Preterm labor did not progress and pregnancy continued till 36 weeks 5 days, when she went into labor. She underwent a LSCS as she was not willing for a trial of vaginal birth after a cesarean section. Heparin was stopped before LSCS and was restarted after 6 hours post operatively. She gave birth to a 2.308 kg female child who was assessed by the neonatologists. The neonate did not have hydrocephalus and was neurologically normal. She was stable in the post operative period. On day 5 of LSCS, oral warfarin 5 mg OD was restarted, along with overlapping heparin. APTT was monitored. Eventually heparin was omitted and oral warfarin was continued. She was advised to follow up with the cardiologist, neonatologist and us. Sutures were removal on day 14. Wound had healed well.
Pregnancy induced physiological changes in cardiovascular system has a profound effect on underlying heart disease. Cardiac output increases by more than 40%, heart rate increases and there is a decrease in both systemic and pulmonary vascular resistance. Almost half of the increase in the cardiac output takes place by as early as 8 weeks and all of it by mid pregnancy. Increase in the cardiac output continues to occur throughout pregnancy to up to approximately 40% of the non pregnant state. Women with underlying heart disease are unable to accommodate to these changes and cardiogenic heart failure may occur. Though it is advisable to perform percutaneous balloon mitral valvuloplasty (PBMV) before pulmonary hypertension (PH) has set in, in patients who have MS with established PH, PBMV still remains an effective option with less procedure time. Balloon valvuloplasty may be employed as a bridge to delivery in pregnant women when a definitive corrective surgery in the form of valve replacement is usually done after delivery. There is a substantial risk of fetal death if cardiac operation under cardiopulmonary bypass (CPB) is required, so open heart surgery during pregnancy is suggested only in extreme conditions. Emergency and redo operations have significant surgical risks even under mechanical circulatory support. Second trimester is more appropriate time for cardiac surgery with good fetal prognosis and lesser chance of fetal anomaly, however poor maternal condition may necessitate intervention in early pregnancy with associated procedural risk to the fetus in the form of anomalies or abortion.[6,7] One such successful case has been published from KEM hospital of mitral valve replacement during pregnancy done at 25 weeks of gestation due to cardiac failure in patient with severe MS with MR with severe pulmonary hypertension, patient survived the procedure, continued pregnancy till term and delivered a live issue by normal vaginal delivery. Fetal prognosis improves if cardiac surgeries are planned later in the pregnancy as reported by Weiss and colleagues. Surgical intervention during pregnancy is done after a serious consideration because of requirement of anticoagulation especially with mechanical prosthetic valves. Porcine valves are preferred during pregnancy. During pregnancy, platelet number and activation of coagulation cascades increases, but contrast fibrinolytic activity decreases. This increases risk of thrombosis in mechanical prosthetic valves (0.7%-6%), so it important to appropriately maintain proper anticoagulation. The procedure of CPB doesn't affect the maternal survival as much as fetal outcome. Maternal outcome in pregnancy is almost equal to that in non pregnant state (1.47%) whereas a fetal mortality of around 16-33% has been still recorded. In a survey done over 35 years in Mayo Clinic 21 pregnant patients who underwent cardiothoracic surgeries during that period were considered. Out of these, 52% of them had premature deliveries and 3 were fetal deaths (14%). The various neonatal complications were growth retardation (5%), respiratory distress syndrome (33%) and developmental delay (14%). There haven't been many studies performed on the fetal circulation during CPB. CPB results in poor placental perfusion and poor respiratory gas exchange due to lower placental flow and pressure along with hypothermia which further worsens the fetal perfusion.  Cardiac surgery can be performed with relative safety during pregnancy by adopting normothermic, high flow rate circulation and continuous fetal activity monitoring.
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Harsha A, Pardeshi S, Gupta AS. Successful Outcome With Mitral Valve Replacement In Pregnancy. JPGO 2017. Volume 4 No.11. Available from: http://www.jpgo.org/2017/11/successful-outcome-with-mitral-valve.html