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Left ventricular end-diastolic volume during supine exercise in patients with healed myocardial infarction
Insights
Patients with prior myocardial infarction exhibit reduced left ventricular compliance, not heart failure, during exercise. Their hearts maintain functional reserves despite advanced coronary heart disease.
Area of Science:
- Cardiology
- Cardiovascular Physiology
Background:
- Patients with a history of myocardial infarction (MI) and without heart failure signs require evaluation during exercise.
- Assessing left ventricular (LV) function in these patients is crucial for understanding disease progression.
Purpose of the Study:
- To investigate the hemodynamic and functional responses of the left ventricle during exercise in men with previous MI.
- To differentiate between diminished ventricular compliance and heart failure in this cohort.
Main Methods:
- Investigated 18 men with prior MI at rest and during supine exercise.
- Measured left ventricular end-diastolic volume using 133Xe washout and precordial scintillation counting.
- Assessed cardiac index, stroke index, LV work, LV stroke indices, and LV end-diastolic pressure.
Main Results:
- Cardiac index increased with heart rate acceleration; stroke index remained unchanged during exercise.
- Elevated LV end-diastolic pressure at rest reached higher values during exercise.
- LV end-diastolic and residual volumes decreased during exercise, with a simultaneous increase in systolic ejection fraction.
- Patients with LV aneurysm or dyskinesis showed similar end-diastolic volumes compared to others.
Conclusions:
- The left ventricle in patients with advanced coronary heart disease and prior MI demonstrates diminished compliance rather than overt heart failure during exercise.
- Despite limitations, the left ventricle retains some functional reserves during adequate exercise.
- Angina pectoris during exercise did not correlate with significant hemodynamic differences.
Abstract:
Eighteen men with myocardial infarction in their history and without signs of heart failure were investigated at rest and during standard supine exercise. In nine patients aneurysma or diskinesis of the left ventricular wall were found. The left ventricular end-diastolic volume was determined from the wash-out of 133Xe injected into the left ventricle by means of precordial scintillation counting. During exercise the cardiac index rose owing to acceleration of the heart rate, whereas the stroke index remained unchanged, and the left ventricular work and stroke indices increased. The left ventricular end-diastolic pressure, elevated at rest, reached high values during exercise. The left ventricular end-diastolic and residual volumes decreased during exercise in most patients, and simultaneously the systolic ejection fraction increased. In patients with aneurysma or diskinesis the end-diastolic volume both at rest and during exercise does not differ from EDV of other patients. Six patients developed angina pectoris during exercise, but their haemodynamics did not differ significantly. It is concluded that the left ventricle in patients with advanced coronary heart disease and previous myocardial infarction shows the signs rather of diminished compliance than of heart failure during adequate exercise and still possesses some functional reserves.