Altered left ventricular-arterial coupling precedes pump dysfunction in early heart failure.

Area of Science:

• Cardiovascular Physiology
• Heart Failure Pathophysiology
• Hemodynamics

Background:

• Heart failure (HF) is characterized by impaired ventricular-arterial (V-A) coupling.
• The timing of V-A coupling derangements relative to left ventricular (LV) dysfunction in tachycardia-induced HF is not well understood.

Purpose of the Study:

• To define early alterations in V-A coupling during the development of tachycardia-induced HF.
• To investigate the temporal relationship between V-A coupling defects and overt LV dysfunction.

Main Methods:

• Studied six anesthetized dogs before and after 24 hours of rapid ventricular pacing (RVP).
• Measured V-A coupling using end-systolic elastance (E(ES)) and effective arterial elastance (E(A)).
• Assessed mechanical efficiency via stroke work (SW) and pressure-volume area (PVA).

Main Results:

• After RVP, arterial load (E(A), R(T)) increased without significant LV dysfunction.
• V-A coupling (E(ES)/E(A)) and mechanical efficiency (SW/PVA) declined significantly under stress (phenylephrine, dobutamine).
• A loss of V-A coupling reserve was observed during afterload and inotropic challenges post-RVP.

Conclusions:

• V-A coupling defects emerge early in tachycardia-induced HF, preceding significant pump dysfunction.
• These defects are primarily revealed under hemodynamic and inotropic stress.
• Early identification of V-A coupling alterations may be crucial for understanding HF progression.