Related Experiment Videos
Depressed myocardial contractility and normal ejection performance after aortic valve replacement in patients with
K Taniguchi1, S Nakano, H Matsuda
1First Department of Surgery, Osaka University Medical School, Japan.
Insights
Aortic valve replacement improves systolic function in most patients with aortic regurgitation. However, some patients retain depressed myocardial contractility, indicated by abnormal stress-volume relationships post-surgery.
Area of Science:
- Cardiology
- Cardiac Surgery
- Biomedical Engineering
Background:
- Chronic aortic regurgitation leads to left ventricular volume overload and dysfunction.
- Assessing myocardial contractility in these patients is crucial for surgical outcomes.
Purpose of the Study:
- To evaluate the effects of aortic valve replacement on left ventricular function and contractility in patients with chronic aortic regurgitation.
- To identify predictors of persistent myocardial dysfunction after surgery.
Main Methods:
- Left ventricular cineangiography and pressure measurements were performed in 33 patients pre- and post-aortic valve replacement.
- Patients were stratified into three groups based on preoperative end-systolic volume index.
- Afterload and contractility were assessed using end-systolic stress and the stress-to-volume index ratio.
Main Results:
- Aortic valve replacement normalized elevated afterload (end-systolic stress) in all patient groups.
- Systolic pump function (ejection fraction) improved postoperatively, particularly in groups with lower preoperative end-systolic volume index.
- The ratio of end-systolic stress to end-systolic volume index improved but remained subnormal in patients with higher preoperative volumes, indicating persistent depressed contractility.
Conclusions:
- Aortic valve replacement effectively reduces afterload and improves systolic function in many patients with aortic regurgitation.
- A subgroup of patients exhibits persistent myocardial contractility impairment despite improved ejection fraction, highlighting the importance of stress-strain relationship analysis.
Abstract:
Left ventricular cineangiography and pressure measurement were performed in 33 patients with chronic aortic regurgitation before and after aortic valve replacement and in 25 normal control subjects. Stress and volume were analyzed. The 33 patients were divided into three groups based on preoperative end-systolic volume index: 15 with an index of less than 100 ml/m2 (group I), 12 with an index of 100 to 200 ml/m2 (group II), and six with an index of more than 200 ml/m2 (group III). Afterload estimated as end-systolic stress, which was significantly elevated in all groups before operation, returned to normal postoperatively. Systolic pump function improved postoperatively in all groups; group I and group II showing the most improvement with group III still having an abnormal ejection fraction. The ratio of end-systolic stress to end-systolic volume index, which is an index of contractile state that is relatively independent of preload and afterload, was abnormal in each group preoperatively. Postoperatively, the ratio improved in each group (from 2.8 +/- 0.5 to 4.8 +/- 0.9 for group I, from 1.4 +/- 0.3 to 3.2 +/- 0.6 for group II, and from 0.8 +/- 0.2 to 2.6 +/- 0.8 for group III, compared with 5.9 +/- 1.0 for control subjects). Group I had normal values whereas group II and group III had subnormal ratios, suggesting a depressed contractility. All 15 patients in group I had values that fell within the 95% confidence limits of the linear inverse relationship between ejection fraction and end-systolic stress for control subjects. Nine of the 12 patients in group II and all six in group III had values that fell below the 95% confidence limits of the normal ejection fraction-end-systolic stress relationship. Aortic valve replacement may reduce afterload and improve systolic pump function in many patients with aortic regurgitation. However, there is a subgroup of patients who, despite normal or near-normal pump performance as assessed by ejection fraction, have depressed myocardial contractility characterized by an abnormal relationship between end-systolic stress and either ejection fraction or end-systolic volume.