Anesthetic management of a child with complete atrioventricular septal defect and single ventricle posted for noncardiac surgery

Abstract

Congenital heart defects are associated with various physiological disturbances. They pose anesthetic challenges for both cardiac and noncardiac surgeries. Atrioventricular septal defects are due to a developmental failure in the separation of atria and the ventricles into separate chambers and failure in the separation of mitral and tricuspid valves. We present a case of a child (1½ years), weighing 10 kg, diagnosed as congenital hydrocephalus who was planned for ventriculoperitoneal shunt. Child was having an oxygen saturation of 76% on room air. Anesthesia was induced with morphine and propofol. After tracheal intubation, saturation improved to 93%. Anesthesia was maintained with a combination of oxygen and nitrous oxide along with isoflurane. Measures were taken to maintain normovolemia and avoid hypotension, hypoxia, tachycardia, cardiac dysrhythmias and acidosis. The patient remained hemodynamically stable, maintaining arterial blood gasses within normal limits. The overall intraoperative course remained uneventful. At the end of the procedure, patient was reversed with neostigmine 60 mcg/kg and glycopyrrolate 10 mcg/kg. Extubation was done after the child was alert and opening eyes and was shifted to intensive care on oxygen inhalation for further monitoring.

INTRODUCTION

Congenital heart defects present with physiological disturbances and hence pose anesthetic challenges for cardiac and noncardiac surgeries. Atrioventricular (AV) septal defect results from a lack of separation of atria and the ventricles into separate chambers and lack of separation of mitral and tricuspid valves resulting in a large connection between atria and ventricles. A single ventricle has to maintain both the systemic and the pulmonary blood circulation, which is not connected in series but parallel. Such a circuit has disadvantages of arterial desaturation and a chronic volume overload due to the single ventricle. We report a case of complex heart disease with mixed lesions posted for ventriculoperitoneal shunt.

The aim of our anesthetic management was to facilitate the smooth conduct of the procedure and plan for the repair of the definitive cardiac lesion after the patient would recover from the noncardiac surgery. The definitive procedure was delayed in view of the semi-emergent nature of the noncardiac surgery.

CASE REPORT

A 1½-year-old female child, weighing 10 kg, presented with swelling of the head since birth. The baby was sluggish in activity with a history of delayed milestones. On room air, the baby was cyanosed with an oxygen saturation of 76%. She had pulse rate of 110 beats/min and respiratory rate of 36 breaths/min. The child had associated arachnodactyly and clubbing. Cardiovascular examination revealed an ejection systolic murmur. There was no associated organomegaly. Chest roentgenogram showed increased cardiothoracic ratio with bilateral hilar haziness. Echocardiography showed a complete AV septal defect which was associated with an atrial septal defect, ventricular septal defect, pulmonic stenosis and mitral regurgitation. Both aorta and pulmonary trunk were connected to the right ventricle. Computed tomography of the head showed dilatation of both lateral ventricles and third ventricle due to congenital hydrocephalus.

The baby was planned for ventriculoperitoneal shunt. Baby was kept fasting for 6 h before surgery, and an infusion of Ringers lactate was given at 40 ml/h intravenously. Baby was shifted to the operating room on oxygen inhalation. Standard monitors in the form of electrocardiogram, noninvasive blood pressure, and pulse oximetry were connected. Anesthesia was induced with glycopyrrolate 4 mcg/kg, morphine 100 mcg/kg, propofol 2 mg/kg. Atracurium was used at a dose of 0.5 mg/kg to facilitate tracheal intubation. Oxygen saturation improved to 93% after tracheal intubation. Anesthesia was maintained using a combination of oxygen and nitrous oxide along with isoflurane 0.8–1%. Unfortunately due to nonavailability of medical air we were compelled to use nitrous oxide. Furthermore, immediately after endotracheal intubation, the arterial blood gases improved so that we could use nitrous oxide safely.

Muscle relaxation was maintained using bolus doses of 1.5 mg of atracurium using a nerve stimulator measuring two twitches of train of four stimulator. Ventilation was adjusted to maintain normocapnia. Normovolemia was maintained, and measures were taken to avoid hypotension, hypoxia, tachycardia, cardiac dysrhythmias, and acidosis. The central venous pressures were maintained in the range of 7–8 cm of water [Table 1]. The intraoperative course remained uneventful, the patient being hemodynamically stable and arterial blood gasses were within normal limits. The serial arterial blood gasses are tabulated in Table 2.

Table 1.

Central venous pressures

Table 2.

Arterial blood gasses

At the end of the procedure, the patient was reversed using neostigmine 60 mcg/kg and glycopyrrolate 10 mcg/kg. Tracheal extubation was done when the baby was alert and was opening eyes. The patient was shifted to intensive care unit on oxygen inhalation for overnight monitoring.

DISCUSSION

Children with congenital heart disease undergoing noncardiac surgery are at increased risk of perioperative morbidity and mortality compared with other children.[1,2] Preoperative risk factors associated with perioperative complications include poor general health, cyanosis, congestive cardiac failure, and younger age. In case of mixed lesions, there is an unpredictable hemodynamics.

Atrial septal defect associated with left to right intracardiac shunt has minor anesthetic implications. An increase in systemic vascular resistance increases the magnitude of left to right shunt at atrial level. Conversely, a decrease in systemic vascular resistance as produced by volatile anesthetics or increase in pulmonary vascular resistance due to positive pressure ventilation of lungs, tend to decrease magnitude of left to right shunt.[3]

Similarly with an associated ventricular septal defect, pharmacokinetics of inhaled and injected drugs is not significantly altered. However, acute and persistent increases in systemic vascular resistance or decreases in pulmonary vascular resistance are undesirable. In this regard, volatile anesthetics (which decrease systemic vascular resistance) and positive pressure ventilation (which increases pulmonary vascular resistance) are well tolerated.[4]

With an associated pulmonic stenosis management of anesthesia is designed to avoid increases in right ventricular oxygen requirements. Therefore, an undesirable increase in heart rate is avoided. The increase in pulmonary vascular resistance due to positive-pressure ventilation of the lungs is unlikely to produce significant increases in the right ventricular afterload and oxygen requirements. Hypotension, cardiac dysrhythmias or increases in heart rate that become hemodynamically significant should be rapidly corrected.[5]

In our patient, we had a mixed lesion with single ventricle resulting in mixing of blood from pulmonary and systemic circulations manifesting as cyanosis and arterial hypoxemia. Oxygenated blood goes into the left atrium and then into the single ventricle that finally empties into the systemic circulation.[6] The mixing of blood from both circulations results into higher oxygen saturation of pulmonary arterial blood than that of systemic venous blood. The systemic arterial blood has lower oxygen saturation than that of pulmonary venous blood.[5]

Intravascular volume being the main determinant of central venous pressure, hypovolemia is poorly tolerated. Other complications to be taken care of include arrhythmias,[7] thromboembolism,[8] and ventricular dysfunction.[9]

To our best knowledge, we did not come across any case in literature where a child with complete AV septal defect and single ventricle was operated for noncardiac surgery.

CONCLUSION

The anesthetic management of patients with congenital heart diseases coming in for noncardiac surgery needs a good understanding of the physiology of the underlying disease and detailed knowledge about the pharmacological effects of anesthetic drugs in such pathological situations. Normovolemia needs to be maintained, and hypercarbia, hypoxia, and acidosis should be avoided for optimal outcome of the patient.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.