Atrioventricular Septal Defect (AVSD) – Hemodynamics

Preoperative Hemodynamics

In atrioventricular septal defect (AVSD), both atrial and ventricular septa are deficient, and a common atrioventricular valve contributes to abnormal flow dynamics.

• Left-to-right shunting occurs at both atrial and ventricular levels, leading to excessive pulmonary blood flow.
• This results in right atrial and right ventricular volume overload, predisposing to dilation and eventual dysfunction.
• The increased pulmonary flow also heightens the risk of pulmonary hypertension (PH), particularly if repair is delayed.
• Atrioventricular valve regurgitation, especially of the left AV valve component, is common and causes left atrial and left ventricular volume overload.
• Collectively, these abnormalities lead to chamber enlargement: RA, RV, LA, and sometimes LV.

Postoperative Hemodynamics

Definitive surgical repair includes closure of the atrial and ventricular septal components and reconstruction of the common AV valve into separate right and left valves.

• Elimination of shunts relieves the RA and RV volume burden, improving hemodynamics.
• However, long-term outcomes depend heavily on the integrity of the AV valve repair:
• Residual regurgitation can result from incomplete cleft closure.
• Valve stenosis may occur if the repair is overly restrictive.
• Additional risks include pulmonary artery stenosis, particularly in patients who previously underwent pulmonary artery banding (PAB).

Clinical Summary

• Before repair: AVSD produces bi-ventricular volume overload due to atrial and ventricular shunting, compounded by AV valve regurgitation and risk of pulmonary hypertension.
• After repair: Hemodynamic burden is relieved by shunt closure, but careful long-term monitoring is required for AV valve competence and pulmonary artery stenosis.