Isometric handgrip echocardiography: A noninvasive stress test to assess left ventricular diastolic function

Abstract

Background: Cycle exercise echocardiography is a useful tool to "unmask" diastolic dysfunction; however, this approach can be limited by respiratory and movement artifacts. Isometric handgrip avoids these issues while reproducibly increasing afterload and myocardial oxygen demand.

Hypothesis: Isometric handgrip echocardiography (IHE) can differentiate normal from abnormal diastolic function.

Methods: First recruited 19 young healthy individuals (mean age, 24 ± 4 years) to establish the "normal" response. To extend these observations to a more at-risk population, we performed IHE on 17 elderly individuals (mean age, 72 ± 6 years) with age-related diastolic dysfunction. The change in the ratio of mitral valve inflow velocity to lateral wall tissue velocity (E/e'), a surrogate for left ventricular filling pressure, was used to assess the diastolic stress response in each group.

Results: In the young subjects, isometric handgrip increased heart rate and mean arterial pressure (25 ± 12 bpm and 26 ± 17 mmHg, respectively), whereas E/e' changed minimally (0.6 ± 0.9). In the elderly subjects, heart rate and mean arterial pressure were similarly increased with isometric handgrip (19 ± 16 bpm and 25 ± 11 mmHg, respectively), whereas E/e' increased more dramatically (2.3 ± 1.7). Remarkably, 11 of the 17 elderly subjects had an abnormal diastolic response (ΔE/e': 3.4 ± 1.1), whereas the remaining 6 elderly subjects showed very little change (ΔE/e': 0.3 ± 0.7), independent of age or the change in myocardial oxygen demand.

Conclusions: IHE is a simple, effective tool for evaluating diastolic function during simulated activities of daily living.

Keywords: Aging; Diastolic Function; Diastolic Stress Test; Isometric Handgrip; Stress Echocardiography.

Figure 1

Representative heart rate and arterial BP response to IHE in young healthy individuals, showing (A) a representative ECG tracing for a healthy young individual at rest and during isometric handgrip exercise stress at 40% MVC; (B) average group heart rate response at rest and during IHE; (C) representative arterial BP tracing at rest and during IHE; and (D) average group MAP response at rest and during IHE. Grouped data shown as mean and 95% CI. Abbreviations: BP, blood pressure; CI, confidence interval; ECG, electrocardiogram; IHE, isometric handgrip echocardiography; MAP, mean arterial blood pressure; MVC, maximal voluntary contraction

Figure 2

Example of a Doppler mitral inflow velocity tracing for a representative responder (1) at rest and (3) during isometric handgrip exercise stress at 40% MVC, along with tissue Doppler tracing from the lateral wall of the same individual taken (2) during rest and (4) during isometric handgrip exercise stress at 40% MVC. Also shown is change in (A) heart rate, (B) MAP, and (C) LV early mitral inflow velocity to early annular tissue velocity (E/e') from rest to IHE in nonresponders and responders. Each specific symbol represents data from a single individual and is consistent across parameters. Heart rate and BP responded similarly between both groups; however, the responders had an abnormal rise in E/e' (defined as >1.5), a surrogate measure of LV filling pressure, in response to isometric handgrip stress. Abbreviations: BP, blood pressure; IHE, isometric handgrip echocardiography; LV, left ventricular; MAP, mean arterial blood pressure; MVC, maximal voluntary contraction