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Left ventricular response to graded isometric exercise in patients with coronary heart disease
Insights
Isometric exercise reveals progressive left ventricular dysfunction in coronary artery disease (CAD) patients. Echocardiography detected deteriorating cardiac performance during graded handgrip maximal voluntary contraction (MVC) in CAD, unlike in healthy individuals.
Area of Science:
- Cardiology
- Exercise Physiology
- Diagnostic Imaging
Background:
- Left ventricular (LV) function assessment is crucial in coronary artery disease (CAD).
- Isometric exercise elicits cardiovascular responses that can unmask underlying cardiac impairments.
- Echocardiography is a non-invasive tool for evaluating cardiac structure and function.
Purpose of the Study:
- To characterize the effects of graded isometric exercise on left ventricular performance in patients with CAD.
- To compare the echocardiographic responses to isometric exercise between CAD patients and healthy subjects.
- To determine if echocardiography can detect exercise-induced left ventricular dysfunction in CAD.
Main Methods:
- 11 male patients with CAD and 12 healthy subjects underwent echocardiography.
- Subjects performed isometric handgrip exercise at 40% and 60% of maximal voluntary contraction (MVC).
- Echocardiographic indices including LV dimensions and mean velocity of circumferential fiber shortening (mVCF) were measured at rest and during exercise.
Main Results:
- Heart rate and blood pressure increased significantly in both groups during isometric exercise.
- In CAD patients, LV end-diastolic and end-systolic dimensions increased significantly with increasing MVC, while mVCF decreased.
- Healthy subjects showed no significant changes in LV dimensions or mVCF during isometric exercise.
Conclusions:
- Graded isometric exercise progressively deteriorates left ventricular function in patients with CAD.
- Echocardiography effectively detects these exercise-induced functional changes in CAD.
- Isometric exercise serves as a valuable stress test for identifying left ventricular dysfunction in coronary artery disease.
Abstract:
The effects of graded isometric exercise on left ventricular performance were characterized in 11 male patients (53 +/- 2 years) with coronary artery disease (CAD) and in 12 normal subjects (11 male and one female 35 +/- 5 years). The echocardiographic indices of left ventricular function at rest were similar in both groups. Heart rate and blood pressure increased significantly in both groups in response to 40 and 60% of handgrip maximal voluntary contraction (MVC). Left ventricular end-diastolic dimension increased significantly (from 50 +/- 1 to 56 +/- 1 mm; P less than 0.01) with 60% of MVC in CAD group but not in the healthy subjects. The patients with CAD also exhibited significant (P less than 0.01) increases in end-systolic dimension (from 34 +/- 1 to 40 +/- 2 with 40% and to 44 +/- 1 mm with 60% MVC). End-diastolic and end-systolic dimensions did not change during isometric exercise in the healthy subjects. In the CAD group mVCF decreased significantly (from 1.08 +/- 0.06 to 0.86 +/- 0.06 with 40% and to 0.74 +/- 0.04 d . s-1 with 60% MVC; P less than 0.01). At comparable mean blood pressures, mVCF was significantly lower in the CAD group than in normal subjects. These results demonstrate that progressive deterioration of left ventricular function during increasing levels of isometric exercise in patients with CAD can be detected with echocardiography.