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Impaired right ventricular filling in old myocardial infarction
H T Bai1, K Fujitani, H Fukuzaki
1First Department of Internal Medicine, Kobe University School of Medicine, Japan.
Insights
Myocardial infarction impacts ventricular filling and function. Anterior infarction indirectly impairs right ventricular filling, while inferior infarction directly affects it due to wall motion abnormalities.
Area of Science:
- Cardiology
- Cardiovascular Physiology
- Medical Imaging
Background:
- Myocardial infarction (MI) can lead to significant alterations in cardiac function.
- Understanding ventricular interactions and filling dynamics post-MI is crucial for patient management.
Purpose of the Study:
- To evaluate ventricular filling and right and left ventricular interactions in patients with old myocardial infarction.
- To compare these parameters in patients with anterior MI versus inferior MI.
Main Methods:
- Cineangiographic analysis of right and left ventricular time-volume curves in 3 groups: normal subjects, old anterior MI, and old inferior MI.
- Calculation of ventricular volumes, peak ejection rates, peak filling rates, and atrial kick rates using Simpson's method.
- Normalization of parameters by end-diastolic volume; analysis of correlations between ventricular function parameters.
Main Results:
- Patients with old anterior and inferior MI showed significantly lower left ventricular ejection fractions compared to controls.
- Reduced peak ejection and filling rates were observed in both anterior and inferior MI groups.
- In anterior MI, right ventricular filling correlated with left ventricular filling and ejection fraction, suggesting indirect impairment.
- In inferior MI, reduced right ventricular filling correlated with wall motion abnormalities, indicating direct impairment.
Conclusions:
- Old anterior myocardial infarction leads to indirect impairment of right ventricular filling, linked to left ventricular dysfunction.
- Old inferior myocardial infarction causes impaired right ventricular filling due to direct right ventricular wall motion abnormalities.
- Ventricular interactions are significantly altered following myocardial infarction, with distinct mechanisms depending on infarct location.
Abstract:
To evaluate ventricular filling and interactions between right and left ventricles in patients with old myocardial infarction, right and left ventricular time-volume curves were analyzed from a cineangiographic study of 10 normal subjects (Group 1), 10 patients with old anterior myocardial infarction (Group 2) and 10 patients with old inferior myocardial infarction (Group 3). Volumes of both ventricles were calculated from each frame over an entire cardiac cycle using Simpson's method. From time-volume curves, peak ejection rates, peak filling rates and atrial kick rates were obtained for both ventricles and these parameters were normalized by end-diastolic volume. All patients were in sinus rhythm with heart rates less than 80 beats/min. There were no significant differences among the 3 groups in end-diastolic pressure of both ventricles and mean pulmonary artery pressure. Left ventricular ejection fractions were significantly lower in Groups 2 and 3 than in Group 1 (p less than 0.001, p less than 0.005, respectively), although there were no significant differences in end-diastolic volume indexes of either ventricle among the 3 groups. Peak left ventricular ejection rate and peak filling rates of the left and right ventricles were lower in Group 2 than in Group 1 (p less than 0.01, p less than 0.05, p less than 0.01, respectively) and peak filling rate of the right ventricle in Group 2 correlated with the peak filling rate of the left ventricle and left ventricular ejection fraction (r = 0.64, r = 0.64, respectively). Peak filling rate of the right ventricle in Group 2 correlated inversely with left ventricular peak negative dp/dt (r = -0.72), but no correlation was found between peak filling rate of the right ventricle and left ventricular end-diastolic volume index or mean pulmonary artery pressure. Peak ejection rate of the left ventricle and peak filling rates of both ventricles in Group 3 were lower than in Group 1 (p less than 0.02, p less than 0.02, p less than 0.01, respectively) and no correlation was found between peak filling rates of both ventricles. Wall motion of the right ventricular septal portion was slightly reduced in 5 patients in Group 2. In all patients in Group 3, right ventricular wall motion centering around the right ventricular diaphragmatic portion was reduced. These results suggest that in old inferior myocardial infarction, right ventricular wall motion abnormality results in impaired right ventricular filling, whereas in old anterior myocardial infarction, right ventricular filling is reduced indirectly due to impaired left ventricular filling.