Blood pressure, arterial waveform, and arterial stiffness during hemodialysis and their clinical implications in intradialytic hypotension

Research Progress and Clinical Value of Subendocardial Viability Ratio

Cardiovascular disease remains the leading cause of morbidity and mortality worldwide, with ischemic heart disease being a major contributor, either through coronary atherosclerotic plaque-related major vascular disease or coronary microvascular dysfunction. Obstruction of coronary blood flow impairs myocardial perfusion, which may lead to acute myocardial infarction in severe cases. The subendocardial viability ratio, also known as the Buckberg index, is a valuable tool for evaluation of myocardial perfusion because it reflects the balance between myocardial oxygen supply and oxygen demand. The subendocardial viability ratio can effectively evaluate the function of the coronary microcirculation and is associated with arterial stiffness. This ratio also has potential value in predicting adverse cardiovascular events and mortality in various populations. Moreover, the subendocardial viability ratio has demonstrated clinical significance in a range of diseases, including hypertension, aortic stenosis, peripheral arterial disease, chronic kidney disease, diabetes, and rheumatoid arthritis. This review summarizes the applications of the subendocardial viability ratio, its particular progress in the relevant research, and its clinical significance in cardiovascular diseases.

Effect of Intradialytic Exercise on Cardiovascular Outcomes in Maintenance Hemodialysis: A Systematic Review and Meta-Analysis

Key Points

Individuals receiving hemodialysis have high rates of cardiovascular disease not explained by traditional cardiovascular risk factors. Intradialytic exercise improves cardiovascular outcomes, including arterial resistance, BP, and heart rate variability. Clinicians should consider including intradialytic aerobic exercise programs in hemodialysis care to supplement broader treatment plans.

Background

Cardiovascular disease is the leading cause of death among people with kidney failure on hemodialysis, for whom improving cardiovascular health is a research priority. Intradialytic myocardial stunning is common and associated with adverse cardiovascular events. Intradialytic exercise may mitigate intradialytic myocardial stunning and improve cardiovascular structure and function. This systematic review investigated the effect of intradialytic exercise on cardiovascular outcomes in adults undergoing maintenance hemodialysis (PROSPERO CRD42018103118).

Methods

Following Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines, we systematically searched MEDLINE, Embase, Cochrane CENTRAL, SportDiscus, and PEDro databases from 1960 until June 2022, for randomized and nonrandomized studies investigating the effect of intradialytic exercise programs on objective cardiovascular outcomes, prespecified as primary or secondary outcomes. The primary outcome was arterial resistance.

Results

Of 10,837 references identified, 32 met eligibility criteria. These studies investigated the effect of intradialytic exercise on arterial resistance (eight studies), BP (20 studies), myocardial structure and function (seven studies), endothelial function (two studies), sympathetic overactivity (nine studies), biomarkers of cardiac injury (three studies), and cardiovascular hospitalization and mortality (two studies). Most studies used aerobic exercise as the intervention and usual care (no exercise) controls. Meta-analysis of intradialytic exercise versus usual care resulted in a statistically significant reduction in arterial resistance measured by pulse wave velocity with mean difference −1.63 m/s (95% confidence interval, −2.51 to −0.75). Meta-analyses for diastolic BP, left ventricular ejection fraction, and low-frequency/high-frequency ratio measure of heart rate variability also showed statistically significant improvements with exercise. There was no significant difference in change in systolic BP, augmentation index, and left ventricular mass index between groups.

Conclusions

Intradialytic exercise programming resulted in a clinically meaningful improvement to pulse wave velocity, a component of arterial resistance. Improvements in several physiologic measures of cardiovascular health, including diastolic BP, left ventricular ejection fraction, and heart rate variability measured by the low-frequency/high-frequency ratio were also observed. The effects of intradialytic exercise on major adverse cardiovascular events remains uncertain.