Author + information
- Tomoaki Murakami, MD, PhD∗ ( and )
- Koichiro Niwa, MD, PhD
- ↵∗Department of Cardiology, Chiba Children’s Hospital, 579-1 Heta-cho, Midori-ku, Chiba 266-0007, Japan
We read with great interest the article by Redheuil et al. (1), which reported that proximal aortic distensibility was an independent predictor of all-cause mortality and incidence of further cardiovascular events. Concerning congenital heart diseases, there are lots of reports about the decreased distensibility of native and post-operative aortas. We previously reported the decreased ascending aortic distensibility in patients with transposition of the great arteries after arterial switch procedure (2). The decreased aortic distensibility increases the afterload of the left ventricle and is a disadvantage for coronary circulation (3). Therefore, we also examined the subendocardial viability ratio in those patients (4). The subendocardial viability ratio is the ratio of the aortic diastolic pressure time integral and the aortic systolic pressure time integral (tension time index), that is, a measure of hemodynamic capacity for supply divided by myocardial oxygen demand. In that study, the tension time index, which indicates the myocardial oxygen demand, was higher than that in the control subjects, although the subendocardial viability ratio was the same. This pattern of the aortic pressure waveform, an elevated tension time index without a decrease of the subendocardial viability ratio, is similar to that in elderly people, although the patients in our study were elementary school–aged children.
Because preserving the coronary supply–demand balance is essential to sustain life, the subendocardial viability ratio should be maintained constant even in conditions with decreased aortic distensibility. Because the decreased aortic distensibility increases left ventricular workload, it is necessary to increase “supply,” although the stiff aorta is a disadvantage for coronary circulation (3). In our opinion, 1 of the solutions to the problem is aortic dilation. Although the aortic distensibility is decreased, an expanded aorta may be able to store enough blood during systole, which resembles the compensation of a failing heart; that is, although the left ventricular ejection fraction is decreased, the increased left ventricular end-diastolic volume can maintain sufficient cardiac output. Actually, our patients demonstrated aortic dilation (2) (so-called “aortopathy” in congenital heart diseases ). In addition, it is well known that the aortas in elderly people are not only stiff, but also dilated (3).
We would like to know whether the aortic diameter was related to its distensibility in Redheuil et al.’s study (1). Moreover, we are interested in the subendocardial viability ratio and the tension time index of the patients in their study.
Please note: Both authors have reported that they have no relationships relevant to the contents of this paper to disclose.
- American College of Cardiology Foundation
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