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Diastolic pressure-volume relationship during handgrip exercise in patients with coronary artery disease
T Yoshikawa1, T Miyazaki, M Akaishi
1Department of Medicine, Keio University School of Medicine, Tokyo, Japan.
Insights
Isometric handgrip exercise causes an upward shift in the left ventricular diastolic pressure-volume curve in patients with coronary artery disease. This shift is linked to impaired ventricular relaxation and viscoelasticity due to ischemia.
Area of Science:
- Cardiology
- Physiology
Background:
- Mechanisms of left ventricular diastolic pressure-volume curve shifts during ischemia are debated.
- Ischemia can affect diastolic function and ventricular properties.
Purpose of the Study:
- To investigate the effects of isometric handgrip exercise on the left ventricular diastolic pressure-volume curve in patients with coronary artery disease (CAD).
- To explore potential mechanisms underlying observed shifts in the diastolic pressure-volume curve.
Main Methods:
- Constructed left ventricular pressure-volume curves from digitized data in 21 CAD patients and 6 controls during handgrip exercise.
- Analyzed changes in diastolic pressure-volume curve position, left ventricular end-diastolic pressure, ejection fraction, and relaxation parameters.
- Assessed cardiac asynergy and rate-pressure product gain.
Main Results:
- An upward shift in the diastolic pressure-volume curve occurred in 12/21 CAD patients (Group 1) but not in 9/21 CAD patients (Group 2) or controls.
- Group 1 showed increased left ventricular end-diastolic pressure and reduced ejection fraction, with a prolonged time constant for relaxation.
- Group 1 exhibited more extensive cardiac asynergy compared to Group 2.
Conclusions:
- Isometric handgrip exercise can induce an upward shift in the diastolic pressure-volume curve in some CAD patients.
- Incomplete left ventricular relaxation and altered viscoelastic properties associated with ischemia are likely contributors to this phenomenon.
Abstract:
There is some controversy regarding the mechanisms of an upward shift in the left ventricular diastolic pressure-volume curve during ischemia. The effects of handgrip exercise on the pressure-volume curve were examined in 21 patients with coronary artery disease and in 6 control subjects. Pressure-volume curves were constructed from digitized left ventricular pressure and volume derived from biplane left ventriculogram. Diastolic pressure-volume curve shifted upward in 12 patients with coronary artery disease during handgrip exercise (Group 1), but not in the other 9 patients who were similarly afflicted (Group 2). The upward shift did not occur in any control subject. No difference was observed in rate-pressure product gain during exercise. In Group 1, left ventricular end-diastolic pressure increased (p less than 0.01) and ejection fraction was reduced (p less than 0.01), although it did not change in Group 2. In Group 1, the time constant was prolonged (p less than 0.01) with no change in the coefficient for elastic modulus. In Group 2, these parameters remained unchanged. Group 1 was accompanied by more extensive asynergy than Group 2. Thus, isometric handgrip exercise resulted in an upward shift in the diastolic pressure-volume curve in patients with coronary artery disease. Incomplete relaxation and/or the viscoelastic properties of the left ventricle associated with ischemia could be responsible for this phenomenon.