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[Interrelationship of cardiac output and myocardial contractility]
Insights
Stroke volume changes in ischemic heart disease patients without heart failure symptoms do not correlate with disease severity. However, stress test stroke volume trends depend on left-ventricular asynergy and initial cardiac output.
Area of Science:
- Cardiology
- Cardiovascular Physiology
Background:
- Ischemic heart disease (IHD) is a major cause of morbidity and mortality.
- Assessing left-ventricular (LV) function is crucial for managing IHD.
- Early detection of LV dysfunction is vital, even in asymptomatic patients.
Purpose of the Study:
- To investigate the relationship between stroke volume (SV) changes during stress testing and clinical/coronarographic findings in IHD patients.
- To determine factors influencing SV response to stress in IHD.
- To evaluate the sensitivity of LV function curves and SV-total peripheral resistance (TPR) feedback in detecting LV dysfunction.
Main Methods:
- Cardiac output measurement using thermodilution in 56 individuals (52 with IHD).
- Calculation of stroke work index, TPR, and LV segmental contractility.
- Assessment of SV changes during stress testing and left ventriculography.
Main Results:
- SV changes during stress testing did not correlate with clinical or coronarographic IHD severity in the absence of circulatory insufficiency symptoms.
- The pattern of SV changes during stress testing was influenced by the extent of LV asynergy.
- Initial cardiac output values significantly affected SV changes.
- LV function curves and SV-TPR feedback demonstrated high sensitivity in identifying LV dysfunction.
Conclusions:
- SV response to stress testing is not a reliable indicator of IHD severity in asymptomatic patients.
- LV asynergy and baseline cardiac output are key determinants of SV behavior during stress in IHD.
- LV function curves and SV-TPR feedback are sensitive tools for detecting subclinical LV dysfunction in IHD.
Abstract:
On examination of 56 persons, 4 were found to have no abnormalities of the cardiovascular system, in all of the others the diagnosis of ischemic heart disease was confirmed. The cardiac output was determined by means of a thermodiluter. The stroke work index, the total peripheral resistance, and the segmental contraction of the left-ventricular wall were calculated. Changes in the stroke volume in response to a stress test, left ventriculography, were studied. It was found that changes in the stroke volume do not correlate with the clinical and coronarographic manifestations of the disease and the condition of the contractility of segments of the left-ventricular wall in the absence of clinical symptoms of circulatory insufficiency. The trend of stroke volume changes recorded during the stress test showed a dependence on the volume and degree of left-ventricular asynergy. Changes in the stroke volume were determined by the initial value of the cardiac output. High sensitivity of the left-ventricular function curve in detecting dysfunction of the left ventricle as well stroke volume-total peripheral resistance feedback were revealed.