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Ischemia in aortic stenosis: hemodynamic prediction
Insights
Hemodynamic indexes, specifically the diastolic pressure-time index/tension-time index ratio, can predict myocardial ischemia in aortic stenosis patients. This helps differentiate ischemia causes and aids in clinical assessment.
Area of Science:
- Cardiology
- Cardiovascular Physiology
Background:
- Aortic stenosis can lead to myocardial ischemia.
- Predicting ischemia in these patients is clinically important.
Purpose of the Study:
- To evaluate hemodynamic indexes for predicting myocardial ischemia in aortic stenosis patients.
- To assess the role of coronary artery disease in ischemia development.
Main Methods:
- Review of 12 patients with aortic stenosis studied before and after isoproterenol infusion.
- Calculation of diastolic pressure-time index (DPTI) and tension-time index (TTI).
- Assessment of myocardial lactate metabolism and calculation of the DPTI/TTI supply/demand ratio.
Main Results:
- Patients with aortic stenosis alone showed ischemia when DPTI/TTI < 0.30.
- Patients with aortic stenosis and coronary artery disease exhibited abnormal lactate metabolism with varying DPTI/TTI ratios.
- Aortic valve areas were comparable across groups.
Conclusions:
- The DPTI/TTI ratio is a useful index for predicting ischemia in aortic stenosis.
- This ratio can help distinguish the contribution of coronary artery disease.
- It serves as an adjunct to valve area calculation, without needing regurgitation quantitation.
Abstract:
The records of 12 patients with aortic stenosis previously studied by Fallen et al. in 1967 before and after infusion of isoproterenol were reviewed to assess the value of hemodynamic indexes in predicting myocardial ischemia--defined as less than 5 percent transmyocardial lactate extraction or lactate production. Potential subendocardial blood supply was estimated from a diastolic pressure-time index (DPTI), calculated from the tension-time index (TTI). The ratio DPTI/TTI was used to estimate the supply/demand relation. Of eight patients with aortic stenosis but without associated coronary artery disease, four (Group A) metabolized lactate normally after administration of isoproterenol, and four (Group B) had biochemical evidence of ischemia. Three of four patients (Group C) with aortic stenosis and associated coronary artery disease had abnormal glycolysis after administration of isoproterenol. Calculated aortic valve areas were comparable in all groups. In patients with aortic stenosis alone, abnormal lactate metabolism occurred whenever DPTI/TTI was less than 0.30 (P smaller than 0.01) (Group B). Two of three patients with aortic stenosis and associated coronary artery disease (Group C) showed abnormal lactate metabolism when DPTI/TTI was greater than 0.6; this ratio was below 0.3 in the third patient. These results suggest that the supply/demand relation calculated from these readily obtained indexes may be useful (1) in predicting in which patients with aortic stenosis ischemia will develop, (2) in distinguishing the role played by associated coronary artery disease, and (3) as an adjunct to calculation of valve area since the quantitation of associated aortic regurgitation is not necessary.