Subendocardial Viability Ratio Estimated by Arterial Tonometry: A Critical Evaluation in Elderly Hypertensive Patients With Increased Aortic Stiffness

Abstract

1. Increased aortic stiffness predisposes to myocardial ischaemia by increasing the systolic tension-time index and by decreasing aortic pressure throughout diastole. The tonometric subendocardial viability ratio (SEVR) is a non-invasive estimate of myocardial perfusion relative to cardiac workload. The hypothesis that SEVR is impaired in elderly hypertensives with high aortic pulse pressure (PP) was tested in the present study. 2. The SEVR was calculated by radial applanation tonometry in 203 subjects. In addition, diastolic time (DT), systolic time (ST) and mean diastolic and systolic aortic pressures (Pd and Ps, respectively) were calculated. First, 60 subjects matched for age and gender were analysed (20 controls, 20 hypertensives with pulse pressure (PP) < or = 60 mmHg, 20 hypertensives with PP > 60 mmHg; mean (+/-SD) age 64 +/- 9 years; 24 women, 36 men). The remaining 143 subjects, aged 53 +/- 10 years, were analysed subsequently. 3. The SEVR was similar in the three elderly groups (1.39 +/- 0.34, 1.39 +/- 0.28 and 1.35 +/- 0.25, in controls and hypertensive patients with PP < or = 60 and > 60 mmHg, respectively). The SEVR was positively related to DT/ST (r(2) = 0.89) and to DT (r(2) = 0.73) and was negatively related to heart rate (r(2) = 0.56; P < 0.001 each). However, SEVR was not related to ST, PP, mean Pd or mean Ps. At a given DT/ST, SEVR tended to be lower in hypertensives with PP > 60 mmHg than in hypertensives with normal PP. The positive linear relationship between SEVR and DT/ST was confirmed in the remaining 143 subjects (r(2) = 0.90), with no influence of aortic pressure. 4. The tonometric SEVR was not impaired in elderly hypertensive patients with increased aortic stiffness. In resting elderly and middle-aged individuals, the tonometric SEVR was mainly related to DT/ST ratio, not to aortic pressure.

Changes in Subendocardial Viability Ratio With Acute High-Altitude Exposure and Protective Role of Acetazolamide

“…26,32 Ferro et al 27 showed a close relation between ischemic threshold and degree of coronary stenosis during diastolic perfusion time, but no correlation was found when explored throughout the whole cardiac cycle. In a recent invasive study, Chemla et al 30 confirmed these observations and showed that diastolic time/left ventricular ejection time ratio is the main factor affecting SEVR and is responsible for 81% of the variability of SEVR in resting humans.…”

“…14,30,31 The importance of diastolic perfusion time as a determinant of subendocardial perfusion has been well demonstrated in experimental studies. 26,32 Ferro et al 27 showed a close relation between ischemic threshold and degree of coronary stenosis during diastolic perfusion time, but no correlation was found when explored throughout the whole cardiac cycle.…”

Subendocardial viability ratio as an index of impaired coronary flow reserve in hypertensives without significant coronary artery stenoses

“…Finally, the calculation of the tonometric SEVR was as provided by the manufacturer and did not include a non-invasive estimate of LV enddiastolic pressure as it is required in patients known or suspected to exhibit elevated LV filling pressure. 30,31 However, none of the studied patients exhibited E/Em values 415, which constitutes a consistent index of increased LV filling pressures.…”

“…In particular, diastolic time fraction is a determinant of both SEVR and coronary flow increase when the autoregulatory mechanism is exhausted because larger fractional diastolic time occurs at lower perfusion pressure, in the presence as well as in the absence of coronary stenosis. 6,14,[30][31][32][33] Alternatively, impaired CFR may provoke diastolic dysfunction as it has been shown that delayed myocardial relaxation associated with less early diastolic filling due to ischaemia occurs early in the setting of reduced CFR before evidence of wall motion abnormalities. 26 The current study is cross-sectional; therefore, causation cannot be determined for any of the observed relationships.…”

Assessment of Vascular Function by Using Cardiac Catheterization

“…Thus, it can be a comprehensive determinant of the cardiac afterload against the pulsatile blood flow. TAC decreases in response to increased arterial stiffness (e.g., due to aging) and is reported to be associated with essential hypertension [27] and the myocardial oxygen demand-supply balance [28].…”