|Year : 2022 | Volume
| Issue : 1 | Page : 74-77
Anaesthetic management of a patient with sub-valvular aortic stenosis for emergency lower segment caesarean section: A case report
Anita R Chhabra1, Prajakta D Shinde1, Vijay L Shetty1, Atul M Ganatra2
1 Department of Anaesthesia, Fortis Hospital, Mulund, Mumbai, Maharashtra, India
2 Department of Obstetrics and Gynaecology, Fortis Hospital, Mulund, Mumbai, Maharashtra, India
|Date of Submission||23-Jun-2021|
|Date of Acceptance||15-Dec-2021|
|Date of Web Publication||14-Mar-2022|
Dr. Anita R Chhabra
1603/1604, Marathon Galaxy 1, LBS Road, Mulund (West), Mumbai - 400 080, Maharashtra
Source of Support: None, Conflict of Interest: None
Sub-valvular aortic stenosis (SAS) occurs due to a fibrous membrane or a muscular narrowing causing left ventricular outflow tract obstruction. The physiological changes of pregnancy may exacerbate the cardiac condition posing significant challenges for anaesthesia and surgery. A 34 years primigravida, with 32 weeks gestation, a known case of sub-valvular aortic stenosis presented in the emergency room in view of leaking/bleeding per-vagina. Risk factors such as tachycardia, decrease in afterload, preload and increased left ventricle contractility lead to exacerbation of the obstruction and should be avoided. We report a successful anaesthetic management of her lower segment cesarean section while balancing the physiological changes of pregnancy superimposed by pathology of the disease.
Keywords: Caesarean section, general anaesthesia, sub-valvular aortic stenosis
|How to cite this article:|
Chhabra AR, Shinde PD, Shetty VL, Ganatra AM. Anaesthetic management of a patient with sub-valvular aortic stenosis for emergency lower segment caesarean section: A case report. J Obstet Anaesth Crit Care 2022;12:74-7
|How to cite this URL:|
Chhabra AR, Shinde PD, Shetty VL, Ganatra AM. Anaesthetic management of a patient with sub-valvular aortic stenosis for emergency lower segment caesarean section: A case report. J Obstet Anaesth Crit Care [serial online] 2022 [cited 2022 Dec 9];12:74-7. Available from: https://www.joacc.com/text.asp?2022/12/1/74/339543
| Introduction|| |
Sub-valvular aortic stenosis (SAS) represents a spectrum of anomalies ranging from simple fibrous membrane, fibromuscular ridge to tunnel like fibromuscular channel along the left ventricular outflow tract (LVOT) causing obstruction. It accounts for 6.5% of all adult congenital heart diseases. It is the second most common type of aortic stenosis, accounting for 14% of LVOT obstruction in the general population, however its incidence in pregnant patients is unknown. SAS can be either fixed stenosis resulting from subaortic membrane or dynamic stenosis because of hypertrophic cardiomyopathy.
Frequently found as an isolated lesion, it has also been observed to be related to other cardiac defects (60%). It is often considered as an acquired disease, since it is seldom diagnosed during infancy and typically manifests in the first decade of life with symptoms of LVOT obstruction, left ventricular hypertrophy (LVH) and aortic regurgitation (AR).
Pregnancy is usually well tolerated in many patients with SAS, although the physiological circulatory changes may unmask the symptoms of LV obstruction and peripartum palpitations and congestive heart failure may occur.
In this case report we describe the anaesthetic management of a parturient with dynamic subaortic stenosis posted for emergency lower segment caesarean section.
| Case History|| |
A 34-years primigravida at 32 weeks gestation presented in the emergency room with preterm labour, bleeding and leaking per-vagina (PV). She was a known case of sub-aortic stenosis and had been operated for cardiac myomectomy at 13 years of age with no past records. Her ante-natal period was unremarkable and safe confinement was planned at 38 weeks. She had received two doses of dexamethasone for baby's lung maturity in the previous week.
She was conscious and oriented, having mild breathlessness (New York Heart Association class 2) associated with dry cough. On examination, it was noted that she was afebrile having heart rate (HR) of 100/min, blood pressure (BP) of 120/70 mm Hg, SpO2 of 100% on room air, clear chest and a mild systolic murmur in the aortic area. Her blood reports were within normal limits.
Her electrocardiogram (ECG) revealed wide QRS complex, LVH, left axis deviation with ST elevation in anterior leads. Her 2D- echocardiogram revealed normal LV, left ventricle ejection fraction (LVEF) of 55%, a normal tri-cuspid aortic valve (AV), with mild AR, LV outlet turbulence with a high gradient of 134/77 mm Hg across AV suggesting SAS.
Multidisciplinary teams were involved including the obstetrician, cardiologist, obstetrics and cardiac anaesthesiologists, cardiac surgery team and intensivists. Emergency caesarean delivery was planned in view of her obstetrics complaints. She was starving adequately. The team of obstetric and cardiac anaesthesiologist planned general anaesthesia with invasive monitoring including trans-oesophageal echocardiography (TEE). Cardiologist advised caution with fluids administration and meticulous haemodynamics control perioperatively. An informed high-risk consent was obtained. A peripheral vein was secured using a 20G Jelco with Ringer's lactate infusion on flow. Premedication for aspiration prophylaxis, injection pantopraozole, 40 mg IV and injection ondansetron 4 mg IV was administered in the ward. In the operation theatre standard ASA monitors (Blood pressure, ECG, SPO2) were attached and a wedge was placed under the right buttock to avoid aorto-caval compression. Prior to induction, invasive lines were secured (right radial artery and right internal jugular vein) under local anaesthesia and ultrasound guidance. Emergency drugs (like inotropes) and resuscitation equipment were kept ready. Cardiac surgery team with standby Extra Corporeal Membrane Oxygenator (ECMO) were available throughout the duration of the surgery Baseline arterial blood gases (ABG) revealed a normal pH of 7.437 with a mild respiratory alkalosis.
Modified rapid sequence intubation was done using injection fentanyl 50 mcg IV slowly to attenuate her sympathetic response followed by injection etomidate (14 mg IV) and injection rocuronium (50 mg IV). A 7.0 mm cuffed endotracheal tube was placed under direct laryngoscopic vision. After intubation, her HR and BP rose briefly to 120/min and 180/110 mm Hg, respectively but were controlled with injection metoprolol 2 mg IV. Post induction HR and BP came down to 94/min and 124/82 mm Hg respectively. A TEE probe was inserted after endotracheal intubation for continuous echocardiographic monitoring. Hundred percent oxygen was administered until the baby was delivered followed by anaesthesia maintenance with air, sevoflurane and injection fentanyl 100 mcg IV. Muscle relaxant top-ups were not required for the duration of the surgery (50 minutes). A 1.7 kg male baby with good APGAR (9 and 10 at 1 and 5 minutes respectively) was delivered. Injection Oxytocin 20 IU in 500 ml kabilyte was given as slow infusion at the rate of 60 ml/hour after delivery.
Her perioperative TEE findings revealed the presence of turbulent flow in LVOT on colour Doppler along with mild mitral regurgitation [Figure 1]. LVOT peak/mean gradient of 32/20 mm Hg under anaesthesia was lower than the pre-operative 2D-echo. Post-delivery the TEE findings remained unchanged. However, no cardiac intervention was needed.
Her intraoperative haemodynamics were unremarkable. Blood loss was approximately 500-600 ml.
At the end of surgery, an ultrasound guided transverse abdominis plane (TAP) block using 20 ml of 0.2% Ropivacaine on either side was administered. Her post-operative ABG showed metabolic acidosis (pH – 7.17, pCO2 – 47.5 mm Hg, HCO3- - 16.9 mmol/L, base excess - -11.1 mmol/L, Lactates – 2.5 mmol/L) for which injection sodium-bicarbonate 50 meq IV was administered. As per our hospital anaesthesia protocol regarding high-risk cardiac cases, we decided to electively ventilate her overnight. After confirming normal ABG and hemodynamic parameters, she was weaned off ventilator the following morning and shifted to ward by evening. Multimodal analgesia including paracetamol and tramadol was administered as per protocol. Her subsequent recovery was unremarkable and she was discharged from hospital after 5 days.
| Discussion|| |
The primary hemodynamic effect on the left ventricle is one of increased afterload, resulting in increased intracavitary pressure and wall stress. The physiological hyperdynamic changes of pregnancy further exacerbate the compromised cardiac status of the patient.
Hypovolemia, aortocaval compression due to supine position and Valsalva manoeuvre also aggravate obstruction by making the LV cavity smaller.
Our patient was operated for cardiac myomectomy at the age of 13 years with satisfactory outcome. Her past echo reports were not available to us. Her current 2D-echocardiogram showed normal LV and AV with high gradient across the LVOT suggesting recurrence. SAS have been reported to recur in 37% cases after surgical resection. There is scant literature detailing SAS in pregnancy, however data extrapolated from valvular aortic stenosis suggest high risk for cardiac complications including heart failure and even mortality.
General anaesthesia with invasive hemodynamic monitoring with continuous TEE was planned. We chose to administer general anaesthesia as the patient had bleeding PV. GA also offers the advantage of better control of haemodynamics and allowed us to insert TEE for continuous echocardiographic monitoring.
Regional anaesthesia has the disadvantage of causing reduction in SVR and precipitate outflow obstruction. Chen et al. have reported aortocaval compression resulting in sudden loss of consciousness associated with bradycardia and hypotension during caesarean section in a patient with subvalvular aortic stenosis who had been given epidural anaesthesia. Modified RSI was done and injection fentanyl, 50 mcg IV was administered as it helps to control the sympathetic surges of intubation with added analgesia. Injection etomidate has cardio-stable properties and was the inducing agent of choice. Injection rocuronium, a rapid acting non-depolarizing muscle relaxant was preferred over succinylcholine as it has little or no cardiovascular adverse effects and presents equally good intubation conditions.
The cardiac surgery team was on standby in preparedness for any impending cardiac decompensation. The use of ECMO aids rapid resuscitation in event of cardiac failure. The target while managing these patients is to maintain optimal preload, systemic vascular resistance (SVR) and HR. Systolic anterior motion (SAM) of the anterior mitral valve leaflet causes LVOT obstruction and increases the LV stress along with mitral regurgitation, diastolic dysfunction and dysarrythmias. TEE is significant to demonstrate beat-to-beat intra-cardiac volume filling, LV contractility, detecting SAM and cardiac failure besides guiding the precise hemodynamic management. SAM is known to cause unexplained sudden hypotension perioperatively. Increased LV contractility combined with decreased preload and SVR increases LVOT gradient with resultant increased SAM due to Bernoulli effect. The LVOT diameter and distance from the mitral coaptation point to the septum (C-sept distance) are also measured, both at the onset of systole. A narrow LVOT (<2.0 cm) and a short C-Sept (<2.5 cm) both increase the likelihood of SAM. [Figure 2] Echocardiography can thus help to diagnose the condition that generally responds to fluid loading, beta-blockers and vasopressors. Optimum anaesthetic management with adequate fluid administration helped to maintain cardio-stability of our patient, hence averting the need for cardiac intervention.
Beta-blockers are recommended for managing hemodynamic surges; however, one must watch for neonatal bradycardia, hypoglycaemia, hypotonia and hypotension, which this baby did not suffer.
Oxytocin was administered as a slow infusion to avoid tachycardia and hypotension. Post-surgery pain management was done using multimodal analgesia including bilateral TAP block in the OT and other IV and oral analgesics during her rest of stay in the hospital.
Our patient suffered metabolic acidosis possibly due to neurohumoral stress response to surgery. She was mechanically ventilated overnight postoperatively as per our hospital policy of management of high-risk cardiac cases. The immediate postpartum period is critical as heart failure has been reported even 48 hours postoperatively, hence full therapeutic and monitoring support in a critical care area should be provided.
Prognosis after SAS surgical correction is usually excellent. However, the LVOT gradient still increases slowly over time especially in females and patients over 30 years. Preconception counselling should stratify the risk in pregnancy, inform possible complications and discuss strategies to ensure safe delivery. Mothers with congenital heart defects have an approximately 3% to 12% risk of passing them on to their children compared with a background risk of 0.8% for the general population, hence it's advisable to get timely genetic counselling and screening.
| Conclusion|| |
Successful management of a parturient with sub-valvular aortic stenosis for emergency caesarean delivery involves multidisciplinary approach including careful planning, comprehensive understanding of cardiac pathophysiology, judicious titration of anaesthetic agents and fluid management guided by advanced invasive monitoring (TEE) to detect LVOT obstruction.
Declaration of patient consent
The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2]