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Mueller maneuver and LV function in coronary artery disease
S M Scharf1, B O Woods, R Brown
1Department of Medicine, Brockton/West Roxbury VA Medical Center, MA 02132.
Insights
Coronary artery disease (CAD) alone does not cause left ventricular (LV) wall akinesis during the Mueller maneuver. Prior transmural myocardial infarction (MI) is necessary for LV akinesis to develop in patients with CAD.
Area of Science:
- Cardiology
- Physiology
Background:
- Decreased pleural pressure during the Mueller maneuver increases left ventricular (LV) transmural pressure, potentially affecting LV function.
- Patients with coronary artery disease (CAD) may exhibit LV wall akinesis during this maneuver, possibly due to ischemia or mechanical inhibition from prior myocardial infarction (MI).
Purpose of the Study:
- To differentiate between ischemia and prior MI as causes of regional LV akinesis during the Mueller maneuver in patients with CAD.
- To determine if CAD alone is sufficient to induce regional akinesis or if prior MI is a prerequisite.
Main Methods:
- Utilized first-pass radionuclide ventriculography (RVG) to assess LV ejection fraction (EF), volumes (EDV, ESV), heart rate, and regional wall motion during the Mueller maneuver.
- Compared four groups: normal subjects, patients with CAD without MI, patients with prior nontransmural MI, and patients with prior transmural MI.
Main Results:
- LV ejection fraction decreased significantly in all patient groups but not in normals during the Mueller maneuver.
- LV wall akinesis during the Mueller maneuver was observed only in patients with prior transmural MI (17/36), not in those with CAD alone or prior nontransmural MI.
- Akinetic segments identified during RVG were not always apparent on routine contrast ventriculography.
Conclusions:
- Prior transmural myocardial infarction, not just coronary artery disease, is necessary for the development of left ventricular wall akinesis during the Mueller maneuver.
- The Mueller maneuver can unmask regional LV dysfunction not evident during routine ventriculography in patients with prior transmural MI.
Abstract:
Decreasing pleural pressure impedes the ejection of blood from the left ventricle (LV), may lead to decreased LV compliance because of interdependence effects and leads to increased transmural LV systolic and diastolic pressure. Previous work from this laboratory has shown that patients with coronary artery disease (CAD) often develop akinetic segments of the LV wall during the Mueller maneuver. In the presence of increased LV transmural pressure regional akinesis could be caused either by the development of regional ischemia or by mechanical inhibition of motion of an area of nonfunctional myocardium as would be caused by previous myocardial infarction (MI). The present study was designed to distinguish between these two mechanisms by determining if the presence of CAD alone is sufficient to lead to regional akinesis or if prior MI is necessary. We used first pass radionuclide ventriculography (RVG) in the 30 degrees LAD supine position to measure LV ejection fraction (EF), end-diastolic (EDV) and end-systolic (ESV) volumes, heart rate and to assess regional wall motion during the Mueller maneuver. This was done in four groups of subjects: 13 normal subjects, 25 patients with CAD but no prior MI, 13 patients with prior nontransmural MI and 36 patients with prior transmural MI. All subjects had angina pectoris and underwent contrast coronary arteriography. Most also underwent routine contrast left ventriculography as well. There were no significant differences among the three patient groups as regards medications, extent and severity of CAD, and response to routine exercise tolerance testing. EF decreased significantly in the three patient groups (4%-9%, p less than 0.01) but not in the normals during the Mueller maneuver. Heart rate increased (5-10 bpm, p less than 0.05) in the normals and in patient groups 2 and 4. EDV decrease in all four subject groups (8%-10%, p less than 0.01), while ESV remained unchanged. Akinesis of the LV wall developed during the Mueller maneuver only in one group-2 patient, but did so in 17/36 patients with prior transmural MI (group 4, p less than 0.001). One-half of the akinetic LV wall segments seen during the Mueller maneuver on RVG were not seen on routine contrast ventriculography. We tested the effects of posture (supine versus upright) on the response to the Mueller maneuver in six normal subjects and found no changes in the response of EDV and ESV to the Mueller maneuver.(ABSTRACT TRUNCATED AT 400 WORDS)