handgrip

Handgrip maneuver involves sustained isometric muscle contraction (e.g., squeezing a dynamometer) which triggers a reflex sympathetic response, increasing systemic vascular resistance (afterload), heart rate, and blood pressure without significantly changing venous return (preload) as dynamic exercise would. This differs from isotonic (dynamic) exercise, which primarily increases cardiac output and venous return.

Clinical utility: Handgrip is a classic bedside test used during cardiac auscultation to help differentiate heart murmurs based on their response to increased afterload: - Increases intensity of: mitral regurgitation, aortic regurgitation, ventricular septal defect murmurs (all worsen with increased afterload/resistance to forward flow). - Decreases intensity of: aortic stenosis murmur (paradoxically may seem softer as gradient changes), and notably decreases the murmur of hypertrophic obstructive cardiomyopathy (HOCM) and mitral valve prolapse click/murmur timing (delays click, decreases intensity) because increased afterload reduces the pressure gradient across the outflow tract obstruction and increases ventricular volume, reducing the dynamic obstruction.

Mechanism: Increased afterload increases resistance to left ventricular ejection, which increases the volume of regurgitant flow through incompetent valves or shunts (MR, AR, VSD), thus increasing their murmur intensity. In contrast, conditions with dynamic outflow obstruction (HOCM) benefit from increased afterload because it increases LV volume and reduces the pressure gradient across the obstruction, thus decreasing murmur intensity.

This is tested alongside other maneuvers such as Valsalva, standing (which decrease preload and increase HOCM/MVP murmurs), and passive leg raise (which increases preload and decreases HOCM/MVP murmurs), forming a common comparison table for boards.

Additionally, in stress cardiac physiology testing, handgrip can be used to elicit signs of coronary ischemia or diastolic dysfunction under increased afterload conditions, relevant in exercise physiology and cardiac stress testing correlations.