V. R. R Chari, MD*, Chhaya M. Suryawanshi, MD*, Preety Sahu**
*Professor, **Postgraduate Resident
Dept of Anesthesiology, Padm. Dr. D. Y. Patil Medical College College & Research Centre, Sant Tukaram Nagar, Pimpri,Pune-18, Maharashtra-411018 (India)
Correspondence: Dr. Preety Sahu, Dept of Anesthesiology, Padm. Dr. D. Y. Patil Medical College College & Research Centre, Sant Tukaram Nagar, Pimpri,Pune-18, Maharashtra-411018 (India); Phone: 08087582578; E-mail: preety.sahu@yahoo.com
ABSTRACT
Atrial septal defect (ASD) is the most common congenital acyanotic heart disease in adults and accounts for 10% of congenital cardiac defects in adults. It is the most commonly seen congenital cardiac lesion in women of child-bearing age and the pregnancy is usually well tolerated. Pulmonary hypertension is defined as a mean pulmonary arterial pressure greater than 25mm Hg at rest or greater than 30mm Hg during exercise. We report a case of a large ASD with mild pulmonary hypertension in a patient who underwent emergency caesarean section under general anesthesia for failure to progress. During the general anesthesia for the procedure our objectives were to avoid hypotension, hypoxemia, hypercarbia, hypothermia, reversal of shunt (Eisenmenger’sHYPERLINK “http://en.wikipedia.org/wiki/Eisenmenger’s_syndrome” syndrome) and fluid overload. The patient had an eventful perioperative course and discharged from the hospital on the 8th postoperative day in good physical condition.
Key words: Atrial septal defect; Pulmonary arterial hypertension; Caesarean section; hypotension; hypoxemia; hypercarbia; Eisenmenger’s syndrome
Citation: Chari VRR, Suryawanshi CM, Sahu P. Anesthetic management of a case of a large atrial septal defect with mild pulmonary hypertension for emergency cesarean section. Anaesth Pain & Intensive Care 2013;17(2):182-184
INTRODUCTION
Atrial septal defect (ASD) is the most common congenital acyanotic heart disease in adults and accounts for up to 10% of cases of congenital acyanotic cardiac defects in adults. There are three distinct types of ASD namely, osteum primum, osteum secundum and sinus venosus defect. The osteum secundum accounts for 70% of ASD cases, with a male:female ratio 1:2.1ASD causes left to right intracardiac shunt with right ventricular volume overload, increased pulmonary blood flow (PBF), pulmonary hypertension, right ventricular hypertrophy and eventually congestive heart failure (CHF). We present a parturient mother known to have osteum secundum type of ASD since childhood and who underwent emergency caesarean section under general (intra venous) anesthesia for failure to progress. Anesthetic management and perioperative strategies are discussed.
CASE REPORT
A 26-years old primigravida, in labor at 37 weeks of gestation with failure to progress during labor was transferred from a private hospital and an emergency cesarean section was planned. Patient was a known case of osteum secundum type of ASD since childhood with the medical history of repeated upper respiratory infections (URTI), moderate breathlessness (NYHA II), but no history of chest pain, palpitations or fatigue. On physical examination pulse was 88/min (Regular), BP was 130/90 mmHg, bilateral pitting pedal edema was present, but the jagular venous pressure (JVP) was not raised on clinical examination. CVS examination revealed pansystolic murmur in the pulmonary and mitral area (suggesting mild mitral regurgitation), wide split and fixed second heart tone (S2). The rest of the physical examination was unremarkable. All the biochemical, hematological and coagulation tests were within normal limits. ECG showed right axis deviation, incomplete RBBB. 2D Echo revealed grossly dilated left and right atrium and right ventricle, large osteum secondum ASD (24 mm in diameter), left to right shunt, mild pulmonary hypertension with an estimated right ventricle systolic pressure of 40 mmHg and ejection fraction of 60%.
Anesthetic management
The patient was transferred to the operating room; a peripheral intravenous (IV) catheter was inserted using a 20G IV cannula and lactated ringer’s solution was started at maintenance. Heart rate, non-invasive BP, ECG, SpO2 and EtCO2 were monitored throughout the anesthesia. As it was an emergency situation, invasive monitoring was not done and fluid assessment was done clinically.
Patient was premedicated with glycopyrrolate 0.2 mg, metoclopramide 20 mg, ondansetron 4 mg and ranitidine 150 mg. The patient was then preoxygenated with 100% oxygen for 3 mins. Anesthesia was induced with propofol 50 mg, ketamine 50 mg and suxamethonium chloride 100 mg. The patient was intubated orally with a 7.0 mm cuffed endotracheal tube. Rocuronium 40 mg was given as a neuromuscular blockade agent. The right hip was elevated with a soft pillow in order to prevent supine hypotension syndrome. Anesthesia was maintained with oxygen 40%, isoflurane 0.6-0.8%, and controlled ventilation. The end-tidal CO2 (EtCO2) was maintained around 32-35 mmHg.
After the delivery of a 2.8 kg female baby with an Apgar scores of 8 (1min) and 10 (5min), oxytocin infusion, 15 units in 500 ml saline, was administered over 20 minutes followed by fentanyl (50mcg) by slow IV push. The procedure lasted 45 minutes. Intraoperatively pulse was 90-110 beats/min, BP was 110/60-140/90mm Hg, SpO2-100%. Lactated ringer’s solution 500 ml and normal saline were given during anesthesia. The urine output was 150 ml during the 45 min procedure. The estimated blood loss during the procedure was 400 ml.
For reversal of neuromuscular block neostigmine + glycopyrrolate was given. Neostigmine was repeated after five minutes to avoid residual neuromuscular block and to improve recovery. Post extubation patient was conscious, responding to verbal commands, normal muscle power, stable BP, HR and SpO2. Patient was monitored in recovery room for 1 hour and then transferred to ICU and discharged on 8thpostoperative day. Her hospital stay was uneventful.
DISCUSSION
We present a case of secondum ASD in a parturient patient who successfully underwent emergency caesarean section for failure to progress. We employed the usuall anaesthetic approach with particular attention to control of factors that may lead sudden pulmonary hypertension with resultant hypoxemia and the potential for the development of acute heart failure, which would have been detrimental to the mother and the fetus.
There are three types of ASD. The sinus venosus type occurs high in the atrial septum near the entry of superior vena cava (SVC) into the right atrium(RA) and is frequently associated with anomalous pulmonary venous connection from the right lung to SVC/RA. Osteum primum anomalies lie adjacent to AV valves either of which may be deformed / regurgitant. Osteum secundum ASD,which accounts for 70% of cases of ASD, involves the fossa ovalis and is midseptal in location.11
It enables blood flow between the left and right atria via the inter-atrial septum , which may not be clinically significant. Patients are usually asymptomatic during childhood. However, symptoms appear later in life and by age 40, 90% of untreated patients have symptoms of exertional dyspnea, fatigue, palpitation or sustained arrhythmia.3 Complications of uncorrected secundum type of ASD include pulmonary arterial hypertension, right sided heart failure, atrial fibrillation/flutter, stroke and Eisenmenger’s syndrome.4
Large ASD (>9mm), may result in a clinically remarkable left-to-right shunt. This extra blood from the left atrium may cause a volume overload of both the right atrium and ventricle. If untreated, it can result in enlargement of the right side of the heart and ultimately heart failure. Changes in SVR during the perioperative period have important implications for patients with ASD.5 The magnitude of left to right shunt depends on size of ASD, ventricular diastolic properties and the relative impedance in pulmonary and systemic circulation.6
The echocardiography can establish the size and location of the ASD, magnitude and hemodynamic impact of the left to right shunt, and the presence and the degree of pulmonary hypertension.7,8 Pulmonary hypertension is classified as mild (36-49 mmHg systolic), moderate (50-59 mmHg), severe (>60 mmHg) based on the estimated right ventricular systolic pressure gradient calculated from Doppler echocardiography.4
Anticipated problems during general anesthesia include air embolism during vascular access, dysrhythmias (5- 10%), heart failure, heart block and infective endocarditis.
Anesthetic techniques commonly used for lower segment caesarean section (LSCS) include regional anesthesia i.e. spinal/epidural anesthesia. However, these techniques carry the risk of sudden and uncontrolled hypotension and unstable hemodynamics with the possibility of reversal of intra cardiac shunt.
We preferred general anesthesia (GA) with controlled ventilation because our patient had arrived in emergency and patient was in labour and in agony. GA provides better haemodynamic stability. 100% oxygen can be given, as the patient had mild pulmonary hypertension. Hypercarbia can be avoided by mechanical ventilation and adjusting tidal volume and respiratory rate. Inflation of the lungs with intermittent positive pressure ventilation (IPPV) leads to release of endogenous nitric oxide and prostaglandins which cause pulmonary vasodilatation.10 IPPV of lungs is well tolerated when there is increased pulmonary blood flow.5 Intraoperatively we reamained vigilant to avoid hypothermia, hypercarbia and hypoxaemia were avoided as these factors can cause reversal of shunt.
Our aim during GA was to maintain adequate preload, avoid increase in the shunt fraction, maintain optimum cardiac contractility, maintain normal SVR and PVR (achieved in this case by administration of ketamine ), near normal heart rate and close monitoring to detect atrial arrhythmias.
Balanced GA in this clinical scenario is unlikely to cause drastic changes in SVR / PVR with minimum effect on shunt. GA will maintain systemic blood flow within normal limits so that pharmacokinetics of inhaled anesthetic is not altered. Intravenously administered medications may be diluted due to increased pulmonary blood flow, however this is s unlikely to alter the clinical response to these medications because the pulmonary circulation time is very short. Perioperative antibiotic cover was provided to prevent subacute bacterial endocarditis.
CONCLUSION
In patients with ASD we should tailor anesthesia technique to avoid increase in pulmonary vascular resistance, decrease in systemic vascular resistance, hypotension, tachycardia, hypoxia, hypercarbia and hypothermia.
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