Comparison Between Invasive and Noninvasive Methods to Estimate Subendocardial Oxygen Supply and Demand Imbalance

Abstract

Background Estimation of the balance between subendocardial oxygen supply and demand could be a useful parameter to assess the risk of myocardial ischemia. Evaluation of the subendocardial viability ratio (SEVR, also known as Buckberg index) by invasive recording of left ventricular and aortic pressure curves represents a valid method to estimate the degree of myocardial perfusion relative to left ventricular workload. However, routine clinical use of this parameter requires its noninvasive estimation and the demonstration of its reliability. Methods and Results Arterial applanation tonometry allows a noninvasive estimation of SEVR as the ratio of the areas directly beneath the central aortic pressure curves obtained during diastole (myocardial oxygen supply) and during systole (myocardial oxygen demand). However, this “traditional” method does not account for the intra‐ventricular diastolic pressure and proper allocation to systole and diastole of left ventricular isometric contraction and relaxation, respectively, resulting in an overestimation of the SEVR values. These issues are considered in the novel method for SEVR assessment tested in this study. SEVR values estimated with carotid tonometry by "traditional” and "new” method were compared with those evaluated invasively by cardiac catheterization. The “traditional” method provided significantly higher SEVR values than the reference invasive SEVR: average of differences±SD= 44±11% (limits of agreement: 23% – 65%). The noninvasive “new” method showed a much better agreement with the invasive determination of SEVR: average of differences±SD= 0±8% (limits of agreement: ‐15% to 16%). Conclusions Carotid applanation tonometry provides valid noninvasive SEVR values only when all the main factors determining myocardial supply and demand flow are considered.

Reply to ‘Known unknowns of sex differences in cardiovascular physiology – can arterial waveforms provide answers?’

“…However, a noninvasively measured SEVR has a high correlation coefficient (0.85) with left ventricular subendocardial to subepicardial blood flow ratio [8]. Moreover, a noninvasive aortic diastolic pressure decay index appears to be no different from an invasive one [7]. Namely, the noninvasive assessments of SEVR and aortic diastolic pressure decay index used in our study are valid and our article provides direct evidence that the predisposition to myocardial ischemia in women is attributable to accelerated diastolic pressure decay.…”

“…As Picone et al [1] pointed out, the SEVR measured noninvasively may be overestimated compared with that measured invasively [6]. A noninvasively measured SEVR does not account for the intraventricular diastolic pressure and proper allocation to systole and diastole of left ventricular isometric contraction and relaxation, respectively [7]. However, a noninvasively measured SEVR has a high correlation coefficient (0.85) with left ventricular subendocardial to subepicardial blood flow ratio [8].…”

Arterial Stiffness, Subendocardial Impairment, and 30-Day Readmission in Heart Failure Older Patients

“…After the achievement of clinical stability, the improvement in ventricular workload as a consequence of the medical therapy, and, the reduced wall stress, may play a compelling role in increasing subendocardial perfusion. Corrected SEVR has been considered a feasible and reproducible technique, aimed at detecting preclinical organ damage in patients with HF (14); furthermore, as far as we could demonstrate with our data, corrected SEVR may be also useful to test eventual improvement after proper medical treatment.…”

“…Lately, several studies shed light on subendocardial perfusion impairment, which can be easily estimated by using subendocardial viability ratio (SEVR) provided by pulse wave analysis (PWA) (14), as the ratio between diastolic pressure time index (DPTI) and systolic pressure time index (SPTI) (15). Considering DTPI, which is the area under the diastolic phase in the aortic pulse wave profile, as an estimation of myocardial oxygen supply, STPI (the area under the systolic phase) as an index of cardiac tissue oxygen consumption (16), and SEVR represents myocardial workload, oxygen supply, and perfusion (17).…”

Arterial Stiffness in Thyroid and Parathyroid Disease: A Review of Clinical Studies

“…Additionally, an increase in heart rate worsens the pressure supply–demand balance, which may cause ischemia of the heart and of tissues with high blood flow supply. These conditions have been widely associated with aortic stiffening [ 88 ].…”