Left ventricular function during isometric hand grip and cold stress in normal subjects.

Area of Science:

• Cardiology
• Nuclear Medicine
• Physiology

Background:

• Isometric exercise and cold stress are proposed alternatives to dynamic exercise for diagnosing obstructive coronary artery disease (CAD).
• Accurate assessment of left ventricular ejection fraction (LVEF) is crucial for cardiovascular evaluation.

Purpose of the Study:

• To evaluate the reproducibility and discriminative ability of isometric exercise and cold stress tests.
• To measure changes in LVEF during these stress protocols in normal subjects.

Main Methods:

• A non-imaging nuclear probe continuously measured LVEF and relative left ventricular volumes.
• 24 normal subjects underwent isometric hand grip and cold water hand immersion tests.
• Repeat testing was performed in 9 subjects to assess reproducibility.

Main Results:

• Both isometric exercise and cold stress induced significant, transient falls in LVEF.
• Mean maximal LVEF fall was 10% during isometric exercise and 7% during cold stress.
• Reproducibility of LVEF changes was acceptable under controlled conditions.

Conclusions:

• Isometric exercise and cold stress tests demonstrate acceptable reproducibility for LVEF assessment in normal individuals.
• The transient and protocol-dependent nature of LVEF changes limits their discriminative ability for obstructive CAD.
• Methodological differences in stress protocols may explain discrepancies in published studies.