Cardiac evaluation in hypotension-prone and hypotension-resistant hemodialysis patients

Hypotension during hemodialysis occurs frequently, but the precise mechanism remains unclear. In this study, the presence of myocardial ischemia and myocardial contractile reserve during infusions of the beta-adrenergic receptor agonist dobutamine was assessed by means of dobutamine-atropine stress echocardiography (DSE) in hypotension-prone (HP) and hypotension-resistant (HR) hemodialysis patients.

Eighteen HP patients (age 53 +/- 6 years) were compared with 18 HR patients (age 53 +/- 3 years), matched with respect to the duration of hemodialysis and cardiovascular history. New wall abnormalities during dobutamine stress reflect the presence of myocardial ischemia, whereas the increase in stroke index and cardiac index reflects myocardial contractile reserve.

Wall motion score at rest (1.42 +/- 0.53 vs. 1.44 +/- 0.57) and dobutamine-induced new wall motion abnormalities (4 vs. 3 patients) between HP and HR patients were similar, but responses of cardiac index, stroke index, and systolic blood pressure to do butamine between the two groups were different. Not withstanding a similar cardiac index at rest (2.4 +/- 1.1 liter/min/m2 in HP and 2.8 +/- 1.2 liter/min/m2 in HR patients), dobutamine-induced increments in the cardiac index were considerably smaller in the former (0.8 +/- 1.3 liter/min/m2) than in the latter patients (2.3 +/- 1.6 liter/min/m2, P = 0.002), predominantly because of a progressive decrease in the stroke index in the HP patients.

Impaired myocardial contractile reserve rather than ischemia is predominant in HP patients. This impaired myocardial contractile reserve may play a role in the development of hemodialysis-induced hypotension.