Verapamil induced ventricular hypertrophy in conscious dogs

Area of Science:

• Cardiology
• Pharmacology
• Veterinary Medicine

Background:

• Verapamil is a calcium channel blocker used for cardiac conditions.
• Long-term effects of verapamil on ventricular mass are not well-established.
• Hypertrophic cardiomyopathy is a condition where verapamil is clinically applied.

Purpose of the Study:

• To investigate the long-term effects of verapamil on ventricular mass and function in conscious dogs.
• To assess changes in cardiac hemodynamics and ventricular hypertrophy following chronic verapamil administration.

Main Methods:

• Conscious dogs underwent hemodynamic monitoring, including heart rate, aortic and left ventricular pressures, and cardiac output.
• Ventricular function was assessed using methoxamine-induced stress tests and left ventriculography.
• Verapamil was infused subcutaneously for a mean of 7.2 months at doses of 0.005 or 0.01 mg.kg-1.min-1.

Main Results:

• Chronic verapamil infusion did not alter resting hemodynamic variables or left ventricular ejection fraction.
• A significant, reversible depression in the slope of the stress ventricular function test was observed.
• Total ventricular weight increased by 22%, with significant hypertrophy in the right ventricle (25%), septum (26%), and left ventricular free wall (19%).
• Increased ventricular weights were not attributed to fibrosis or edema.

Conclusions:

• Chronic verapamil administration in dogs leads to reversible depression of stress ventricular function.
• The study demonstrates significant biventricular and septal hypertrophy following long-term verapamil infusion.
• Verapamil's long-term use may induce cardiac remodeling without affecting resting hemodynamics.