Reduction in ventricular endocardial and epicardial potentials during acute increments in left ventricular dimensions

Area of Science:

• Cardiovascular Physiology
• Electrophysiology
• Cardiac Mechanics

Background:

• Cardiac potentials recorded from the endocardium and epicardium provide insights into myocardial electrical activity.
• Acute changes in ventricular dimensions can influence these recorded potentials.

Purpose of the Study:

• To investigate the relationship between acute changes in left ventricular (LV) dimension and corresponding endocardial and epicardial potentials.
• To determine if changes in ventricular volume affect cardiac electrical recordings.

Main Methods:

• Unipolar potentials were recorded from the endocardium and epicardium of canine ventricles.
• Left ventricular anteroposterior diameter was measured using implanted ultrasonic crystals.
• Acute changes in LV dimension were induced by blood transfusion.

Main Results:

• An 11% increase in LV diameter resulted in a 28% decrease in LV endocardial potentials and a 15% decrease in LV epicardial potentials.
• Right ventricular potentials also decreased significantly with increased LV volume.
• The observed negative linear relationship between potentials and LV diameter was independent of hematocrit.

Conclusions:

• Endocardial and epicardial potentials primarily reflect the electrical activity of immediately adjacent tissues.
• Increased ventricular volume, leading to wall stretching and thinning, may reduce the effective tissue mass contributing to the recorded signal.
• Changes in ventricular potentials may serve as an indicator of acute shifts in left ventricular volume in clinical settings.