Atrioventricular Septal Defect (AVSD)

Anesthesia Implications

Anesthesia Implications

This is a left-to-right (acyanotic) heart defect. Symptoms are typically mild or absent altogether. Most anesthetic plans will not change with these defects unless the patient is demonstrating congestive heart failure. However, caution should always be taken. Broad anesthetic implications of acyanotic congenital heart defects (CHD) include:

Get a detailed medical history – understand all you can about what defect the patient has and how severe the symptoms are. Get surgical history, daily medications, hemodynamic status, and cardiac and lung function.

Reduce left-to-right shunt – Increases in SVR will worsen left-to-right shunting. Sudden increases or decreases in pulmonary vascular resistance or SVR will also be tolerated poorly. Volatile anesthetics, propofol, etomidate, and barbiturates all decrease SVR – so use cautiously.

Limit stress – or anything that would stimulate sympathetic response. Opioids are often used to reduce/eliminate sympathetic responses to pain, laryngoscopy, etc. Use a slow/cautious induction.

Maintain MAP and SVR – Arterial lines and/or central lines are ideally employed to keep tight controls. These patients will not have optimal cardiac reserve.

Avoid shunt reversal – Airway obstruction, hypoventilation, hypoxia, and pulmonary hypertension create greater pressures on the right side of the heart and can reverse the shunt (making it a cyanotic shunt). This is otherwise called Eisenmenger Syndrome.

Debubble – avoid any bubbles in venous lines. These can lead to a paradoxical embolus.

Cardiac bypass – complex congenital defects sometimes require this. Be aware that this may result in hemodilution!

Endocarditis prophylaxis – for 6 months post-surgical repair of the cardiac defect.

Pathophysiology

This condition is categorized as an acyanotic congenital heart disease (CHD).

This particular condition is characterized by incomplete development of the septal tissue surrounding the AV valves or defects in the valves themselves. This defect can result in large shunts at the atrial and ventricular levels.

This is one of the most common CHDs in Down Syndrome patients.

Signs and Symptoms – may include a systolic murmur, right ventricular hypertrophy (RVH), left ventricular hypertrophy (LVH), an enlarged pulmonary artery, weak pulses, cyanosis, poor weight gain, and fatigue.

Repair – performed anywhere between 2 months – 5 years of age. The age of repair depends on the severity of the defect.

References

Nagelhout. Nurse anesthesia. 5th edition. 2014.
Butterworth. Morgan & Mikhail’s Clinical Anesthesiology. 2013. p. 425
Centers for Disease Control. Facts about atrioventricular septal defects. 2019. link