Effects of cardiac resynchronization therapy on coronary blood flow: evaluation by transthoracic Doppler...

Area of Science:

• Cardiology
• Cardiovascular Physiology

Background:

• Limited data exist on cardiac resynchronization therapy's (CRT) impact on coronary blood flow (CBF).
• Conflicting evidence necessitates further investigation into CRT's effects on myocardial perfusion.

Purpose of the Study:

• To assess changes in left anterior descending coronary artery (LAD) flow under various CRT pacing modes.
• To utilize transthoracic Doppler echocardiography (TTE) for evaluating LAD flow dynamics during CRT programming.

Main Methods:

• Twenty-two CRT responders with idiopathic dilated cardiomyopathy were studied.
• Transthoracic echocardiography (TTE) assessed LAD flow and Tissue Velocity Imaging during four pacing modes: intrinsic conduction (IC), right ventricular (RV) pacing, simultaneous biventricular pacing (BVP), and BVP with left ventricular (LV) pre-activation.

Main Results:

• Simultaneous BVP and BVP with LV pre-activation significantly increased mean coronary flow velocity (CFV) compared to IC.
• Peak CFV and LAD flow velocity/time integral were highest during BVP with LV pre-activation.
• Both simultaneous BVP and BVP with LV pre-activation reduced septal-to-lateral delay and increased basal septal peak systolic velocity.

Conclusions:

• CRT, specifically simultaneous BVP and BVP with LV pre-activation, enhances LAD flow in responders with idiopathic dilated cardiomyopathy.
• These pacing strategies improve regional myocardial contraction and decrease intraventricular dyssynchrony.
• TTE is a valuable tool for assessing CRT-induced changes in coronary hemodynamics.