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Abnormal segmental contraction velocity in coronary artery disease produced by isometric exercise and atrial pacing
Insights
Combining atrial pacing and handgrip exercise effectively reveals coronary artery disease by unmasking temporary myocardial dysfunction. This stress test is more sensitive than pacing alone for identifying ischemic contraction disorders.
Area of Science:
- Cardiology
- Physiology
Background:
- Coronary artery disease (CAD) can impair myocardial function.
- Assessing regional myocardial contraction performance is crucial for diagnosing CAD.
- Existing stress tests may not always reveal subtle ischemic dysfunction.
Purpose of the Study:
- To evaluate the efficacy of combined atrial pacing and sustained handgrip exercise as a stress maneuver.
- To identify temporarily dysfunctioning myocardial segments in patients with CAD.
- To compare the diagnostic sensitivity of combined stress versus atrial pacing alone.
Main Methods:
- Two groups of patients (10 controls, 10 with CAD) underwent left heart catheterization and cineangiography.
- Measurements included resting, atrial pacing, and combined atrial pacing and handgrip exercise conditions.
- Regional myocardial contraction was assessed using mean segmental shortening velocities (VSB, VSM, VSA).
Main Results:
- Atrial pacing alone caused significant decreases in VSM and VSA in the CAD group compared to controls.
- Combined pacing and handgrip exercise accentuated these differences, significantly decreasing all three velocities in the CAD group.
- Individual patient analysis revealed abnormal shortening velocities in segments of CAD patients during stress, with new abnormalities appearing during combined stress.
Conclusions:
- Combined atrial pacing and handgrip exercise is a valuable stress test for detecting temporary myocardial dysfunction in CAD patients.
- This combined maneuver is more effective than atrial pacing alone in inducing and identifying ischemic contraction disorders.
- The technique aids in identifying compromised myocardial segments not evident under less strenuous conditions.
Abstract:
Since isometric exercise by sustained handgrip leads to a sizable increase in aortic pressure this maneuver was used in addition to atrial pacing to increase the imbalance between oxygen demand and supply in two groups of patients. Both groups were studied by left heart catheterization and cineangiography in the right anterior oblique projection, at rest, during atrial pacing and during combined pacing and handgrip exercise. Group 1, the control group, consisted of 10 patients without coronary artery disease having an ejection fraction of 0.61 to 0.82. Group 2 was composed of 10 patients with definite obstructive disease of one or more of the three main coronary arteries. At rest, ejection fraction was normal or nearly normal (range 0.54 to 0.78). Regional myocardial contraction performance was assessed by determining mean segmental shortening velocities at the basal (VSB), middle (VSM) and apical (VSA) short ventricular axes. Whereas at rest there was no significant difference between the two groups or any of the three velocities, during pacing, VSM and VSA were significantly smaller in Group 2 than in Group 1 (P smaller than 0.02). During pacing combined with handgrip exercise the difference between the two groups was clearly accentuated, all three velocities being highly significantly decreased in Group 2 (VSB, P smaller than 0.01; VSM and VSA, P smaller than 0.001). When evaluated individually the patients of Group 2 had in 9 segments during pacing values for VSB, VSM and VSA that were below the range of the normal subjects. During pacing combined with handgrip a newly abnormal shortening velocity was observed in 12 segments (VSB abnormal in 3 of 7, VSM in 4 of 7 and VSA in 5 of 7 instances). In conclusion, the combination of atrial pacing and handgrip exercise appears to be a useful stress maneuver to identify temporarily dysfunctioning segments in patients with coronary artery disease in whom atrial pacing alone is not sufficient to induce ischemic contraction disorders.