|Year : 2012 | Volume
| Issue : 1 | Page : 47-49
Central neuraxial anesthesia for caesarean section in parturients with uncorrected tetralogy of fallot: Two cases
Dalim K Baidya, Ritma Dhir, Maya Dehran, Bishnu P Mahapatra
Department of Anaesthesia and Intensive Care, All India Institute of Medical Sciences, New Delhi, India
|Date of Web Publication||4-Aug-2012|
Dalim K Baidya
Department of Anesthesia and Intensive Care, 8/67, All India Institute of Medical Sciences, New Delhi - 110029
Source of Support: None, Conflict of Interest: None
Tetralogy of fallot (TOF) is the most commonly encountered congenital cyanotic heart disease in pregnant females and maternal mortality approaches 10% in unrepaired TOF. General anesthesia is classically considered the technique of choice for incidental surgery in TOF and neuraxial anesthesia is considered relatively contraindicated. However, general anesthesia for caesarean section can increase maternal morbidity. We report two cases of caesarean section performed under combined spinal epidural (CSE) anesthesia and epidural anesthesia respectively in patients with uncorrected TOF. Adequate preloading to maintain hydration, continuous invasive monitoring, gradual extension of neuraxial blockade by epidural/CSE technique, and judicious use of phenylephrine infusion enabled us to successfully manage both the cases without any complication.
Keywords: Caesarean section, spinal-epidural anesthesia, uncorrected tetralogy of fallot
|How to cite this article:|
Baidya DK, Dhir R, Dehran M, Mahapatra BP. Central neuraxial anesthesia for caesarean section in parturients with uncorrected tetralogy of fallot: Two cases. J Obstet Anaesth Crit Care 2012;2:47-9
|How to cite this URL:|
Baidya DK, Dhir R, Dehran M, Mahapatra BP. Central neuraxial anesthesia for caesarean section in parturients with uncorrected tetralogy of fallot: Two cases. J Obstet Anaesth Crit Care [serial online] 2012 [cited 2023 Jan 29];2:47-9. Available from: https://www.joacc.com/text.asp?2012/2/1/47/99325
| Introduction|| |
Tetralogy of fallot (TOF) is the most common congenital cyanotic heart disease in pregnancy and unrepaired TOF is associated with significant fetal and maternal mortality (10%).  Neuraxial anesthesia is considered contraindicated in TOF patients,  and general anesthesia for caesarean section can increase both maternal and fetal morbidity.  We report caesarean section in two patients with uncorrected TOF under central neuraxial blockade.
| Case Reports|| |
A 20-year 50-kg primigravida presented during first trimester of pregnancy with dyspnea gradeI-II, clubbing, cyanosis, and ejection-systolic murmur. TOF was diagnosed and oral metoprolol 25 mg twice daily was started.
In the third trimester, dyspnea worsened to grade II-III. Her pulse was 80/min, blood pressure (BP) 126/72 mmHg; airway - Mallampatti class (MMP)-III, retrognathia, thyromental distance 3.5 cm. Hematocrit was 53%; other hematological and biochemical investigations and electrocardiography (ECG) were normal. Echocardiography revealed TOF with large ventricular septal defect (VSD), infundibular pulmonary stenosis, aortic-override more than 50%, and right ventricular hypertrophy (RVH) with normal biventricular function. Room-air arterial blood gas (ABG) showed pH 7.38, pO 2 46 mmHg, pCO 2 40 mmHg, SaO 2 84%. Oxygen saturation (SpO 2 ) on room air was 85% and 88% on oxygen.
She was taken up for emergency caesarean section at 36th week because of intra-uterine growth retardation and intermittent non-reassuring fetal heart rate pattern. Anti-aspiration and infective endocarditis prophylaxis was administered. Ringer's lactate 500 mL was infused while radial artery cannula and peripheral central line (PICC) were placed. Central venous pressure (CVP) was 9 mmHg. Combined spinal-epidural anesthesia (CSE) was put at L 2-3 level; 0.5% hyperbaric bupivacaine 6.25 mg with fentanyl 25 μg was injected intrathecally. T 10 sensory level was achieved, but BP, SpO 2 , and CVP decreased to 88/46, 78%, and 3 mmHg, respectively. Phenylephrine infusion was started at 50 μg/min after 50 μg bolus. Within 3-4 min, BP and SpO 2 improved. A bolus of 2% lignocaine 5 mL was given through epidural catheter and within 8 min a sensory block till T 4 level was achieved and surgery was started. After 10 min, a 2.1 kg healthy male baby was born. Oxytocin was not required as uterus contracted well. Intraoperative heart rate was between 75 and 90/min, BP 105/68-122/72 mmHg, SpO 2 87-90% and CVP 5-8 mmHg, urine output 250 mL. Blood loss of 400 mL was replaced with ringer's lactate 1 L and 500 mL tetrastarch. She was monitored in the intensive care unit (ICU) after surgery. Phenylephrine was tapered and stopped after 2 h. Post-operative analgesia was adequate with epidural morphine 3 mg every 12 h and oral paracetamol 1 g three times a day. Epidural catheter was removed after 72 h. Postoperative echocardiography showed normal ventricular function and no change in shunt fraction.
A 29 year 5th gravida presented in the 1st trimester with dyspnea grade-II, clubbing, and cyanosis. She was diagnosed to have TOF at 12 years of age and was asymptomatic following corrective surgery. Her four previous pregnancies resulted in two spontaneous abortions and two intrauterine deaths; all managed conservatively in rural hospitals without any maternal complications. Echocardiography revealed partially corrected TOF with large residual VSD, severe right ventricular outflow-tract-obstruction (RVOTO), RVH, and left ventricular ejection fraction 44%. Tab digoxin and furosemide were started.
On admission at 34th week, she had dyspnea grade-II, pulse 76/ min, BP 115/74 mmHg; airway-MMP-II. Her hematology, biochemistry, and ECG were normal. However, hematocrit was 51%, SpO 2 was 83-85% in room air, and 86% on oxygen. ABG showed pH 7.41, pO 2 49 mmHg, pCO 2 36 mmHg, SaO 2 85%. Repeat echocardiography showed ejection fraction of 53%.
Elective caesarean section was planned at 36th week. Anti-aspiration and infective endocarditis prophylaxis was administered. In the operating room, radial artery cannula and PICC were inserted, Ringer's lactate infusion was started and oxygen was provided. An epidural catheter was placed at L 3 -L 4 level and 3 mL of 2% Lignocaine + adrenaline (5 μg/ mL)was injected followed by 8 mL 2%Lignocaine in 4 mL aliquots over 10 min. SpO 2 and BP decreased to 80% and 96/52 mmHg, respectively. Phenylephrine bolus 50 μg was given and infusion started at 30 μg/min. BP and SpO 2 improved to 105/64 mmHg and 87%, respectively. Her sensory level was T 10 which increased to T 6 after 4 mL of 2% Lignocaine was injected. A 1.9 kg healthy male baby was born. Oxytocin 10 unit was slowly infused over 1 h as the uterus was not readily contracted. Blood loss of 600 mL was replaced with 1.5 L Ringer's lactate and 500 mL tetrastarch. Urine output was 300 mL. There was no further desaturation or hypotension. Intermittent ventricular ectopics were observed on monitor during surgery. The patient was transferred to ICU; phenylephrine infusion was stopped after 4 h. Repeat echocardiography showed no change in shunt fraction or ventricular function. Epidural morphine 3 mg 12 hourly and oral paracetamol 1 g 8 hourly were provided for post-operative analgesia. She had good pain relief and epidural catheter was removed after 72 h.
| Discussion|| |
Uncorrected TOF is associated with poor feto-maternal outcome. Severe maternal hypoxemia and polycythemia lead to miscarriage, fetal growth retardation (36%), fetal death (14%), and maternal death (10%). At hematocrit >65%, pregnancy wastage is 100%. ,
Anesthetic goals in TOF are to maintain venous return, SVR, and normal contractility and to prevent rise in PVR and heart rate so that right-to-left shunt does not increase. General anesthesia is considered the technique-of-choice though it can cause rise in PVR due to hypoxia, hypercarbia, acidosis, hypothermia, and positive pressure ventilation; a decrease in SVR due to various anesthetic drugs and thereby increases the risk of cyanotic spells.  Spinal anesthesia is considered contraindicated as it causes sudden fall in SVR,  but it allows spontaneous respiration with little disruption of ventilation-perfusion relationship and no rise in PVR.
Low dose CSE or graded epidural anesthesia allows gradual fall in SVR which can be counter-balanced by adequate intravenous fluids and vasopressors. Intrathecal bupivacaine 5-7 mg as part of CSE provide effective anesthesia for caesarean section and avoid maternal hypotension.  Gradual extension of epidural anesthesia with local anesthetics in small aliquots provided similar advantages in the second patient.
Both the patients received at least 500 mL of crystalloid at the onset of neuraxial blockade. Phenylephrine is the vasopressor of choice as it is pure α1 agonist and maintains BP by increasing SVR without causing tachycardia. Moreover, phenylephrine-induced rise in BP is associated with increased pulmonary blood flow and improved oxygenation in patients with TOF.  However, in spite of intravenous volume loading and early initiation of phenylephrine, there were episodes of transient hypotension and worsening of right to left shunt. Oxytocin bolus should be avoided as it causes hypotension and tachycardia; slow infusion may be given if required as in the second patient. 
In the first patient, the presence of difficult airway could increase the likelihood of maternal respiratory complications and hemodynamic fluctuations had general anesthesia been planned. In view of emergent nature of surgery, CSE was preferred over epidural to achieve early onset of sensory-motor blockade.
Adequate preloading, continuous invasive monitoring, controlled use of phenylephrine infusion, and gradual extension of neuraxial blockade by epidural/CSE technique enabled us to successfully manage both the cases. However, in both the patients, baseline SpO 2 was ≥83-85%. SpO 2 > 85% and a hemoglobin <18 g/dl were associated with less maternal and fetal complications in cyanotic mothers.  Whether the parturients with more severe degree of TOF can tolerate epidural based central neuraxial anesthesia remains unanswered.
In conclusion, epidural/CSE can be a safe and efficacious alternate anesthetic technique for caesarean section in patients with uncorrected TOF.
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