Left ventricular asynchrony: an indicator of regional myocardial dysfunction

Area of Science:

• Cardiology
• Physiology

Background:

• Assessing regional myocardial dysfunction is challenging due to natural variations in wall thickening.
• Absolute values of systolic wall thickening are unreliable for detecting localized dysfunction.

Purpose of the Study:

• To investigate if left ventricular asynchrony can quantify regional myocardial dysfunction severity during ischemia and reperfusion.
• To determine if asynchrony measures are useful when baseline function is unknown.

Main Methods:

• Used sonomicrometry in dogs to measure regional myocardial wall thickness under control, ischemic, and reperfusion conditions.
• Calculated two indexes of left ventricular asynchrony: postejection thickening (PET) and phase difference (PD).

Main Results:

• Systolic wall thickening decreased significantly with increasing ischemia severity.
• PET and PD increased progressively with ischemia severity.
• Inverse linear relationships were found between systolic wall thickening and both PET and PD (r = -0.86 and -0.87, respectively).
• Inotropic stimulation affected wall thickening but not asynchrony levels.
• PET and PD did not correlate with late reperfusion contractile function recovery.

Conclusions:

• Left ventricular asynchrony (PET and PD) can reliably quantify regional myocardial dysfunction severity, even without known baseline function.
• Asynchrony measures are valuable for assessing myocardial dysfunction during ischemia and reperfusion.
• PET and PD are not predictive markers for the functional recovery of myocardium after reperfusion.