[Left ventricular wall stress and contractile function immediately after arterial switch operation in neonates]

Area of Science:

• Pediatric Cardiology
• Cardiac Surgery
• Echocardiography

Background:

• Left ventricular function dynamics post-arterial switch operation (ASO) in neonates are not well understood.
• Assessing myocardial contractility and ventricular load is crucial for managing these complex congenital heart defects.

Purpose of the Study:

• To evaluate left ventricular end-systolic wall stress (ESWS) and the stress-velocity index (S-V Index) immediately after ASO in neonates.
• To determine if preoperative left ventricular characteristics predict postoperative function.

Main Methods:

• Echocardiography was used to measure ESWS and rate-corrected mean velocity of fiber shortening (mVcfc) in 11 neonates post-ASO.
• The S-V Index, a load-independent measure of contractility, was calculated.
• Preoperative echocardiographic parameters were correlated with postoperative S-V Index and ESWS.

Main Results:

• The mean S-V Index was normal (0.80 +/- 3.11) immediately after ASO, with normalization within 12 hours in most cases.
• One case of acute heart failure due to elevated afterload showed delayed S-V Index recovery.
• Preoperative end-diastolic posterior wall thickness and LVPWTd/LVDd ratio correlated significantly with postoperative S-V Index and ESWS.

Conclusions:

• Left ventricular function, assessed by the S-V Index, is generally preserved immediately after ASO in neonates.
• Preoperative left ventricular geometry is a significant predictor of postoperative myocardial contractility and load.
• These findings can inform surgical strategies and postoperative management for neonates undergoing ASO.