Standing transthoracic echocardiography: a feasibility study

Orthostatic hypotension (OH) is associated with cardiovascular disease, particularly among older adults. While a standing transthoracic echocardiogram (TTE) could theoretically identify changes in cardiac output to diagnose cardiogenic OH, there are no established protocols for orthostatic TTEs and their feasibility is unknown.

We recruited 115 patients scheduled for elective outpatient TTE. Consenting participants, who were able to stand safely, underwent their scheduled recumbent TTE, followed by a standing TTE, performed within 1-2 minutes of standing. The focused TTE used the apical window to measure velocity time integral across the aortic valve to assess cardiac output. Blood pressure (BP) was measured in the supine and standing positions and patients were asked about symptoms of dizziness and lightheadedness. OH was defined as a change in standing minus supine systolic BP ≤-20 mm Hg or in diastolic BP of ≤-10 mm Hg. Of the 115 enrolled participants, 102 (89%) completed the standing echocardiogram protocol. Among those completing, mean age was 63.4 (SD, 14.8) years (38% were ≥ 70 years), 48% women, and 34% had a BMI ≥ 30 kg/m². There were 21% with OH. Upon standing, systolic BP changed by -5.9 mm Hg (95% CI: -9.5, -2.2), diastolic BP by 2.4 mm Hg (-0.1, 4.8), and cardiac output by -0.4 L/min (95% CI: -0.7, -0.1). Change in cardiac output (per 1 L/min) was associated with a higher odds of systolic OH (OR: 1.60; 95% CI: 1.05, 2.42), but not diastolic OH (OR: 1.21; 95% CI: 0.63, 2.32).

Standing TTE is safe, well-tolerated, and feasible in the ambulatory setting. Moreover, TTE changes in cardiac output are associated with systolic OH. This clinical assessment shows promise for distinguishing OH etiologies and could inform further research on treatments to prevent OH.