ROBERTO M. LANG, M.D.; SUSAN K. FELLNER, M.D.; ALEXANDER NEUMANN, B.S.; DAVID A. BUSHINSKY, M.D.; KENNETH M. BOROW, M.D.
Study Objective: To determine the effect of variations in blood ionized calcium (Ca2+) on myocardial contractility independent of changes in loading conditions and other biochemical variables.
Design: Hemodialysis done in a randomized, double-blind manner with dialysates differing in calcium concentration only. Left ventricular contractility was assessed using the load- and heart rate-independent relationship between end-systolic wall stress (<es) and rate-corrected velocity of fiber shortening (Vcfc).
Setting: In-hospital dialysis unit and echocardiography laboratory of a university medical center.
Patients: Seven patients with stable, chronic renal failure maintained on regular hemodialysis.
Interventions: Each patient was hemodialyzed three times within 1 week with dialysates differing in calcium concentration only. Ultrafiltration was adjusted to achieve the same postdialysis weight. Immediately after dialysis, two-dimensionally targeted M-mode echocardiographic and calibrated carotid pulse tracings were recorded over a wide range of left ventricular end-systolic wall stress values (a measure of left ventricular afterload) generated by either methoxamine or nitroprusside.
Measurements and Main Results: After dialysis, three statistically distinct levels of Ca2+ were achieved. When Ca2+ was 1.34 ± 0.03 mmol/L, Vcfc, calculated at a common level of afterload (<es = 50 g/cm2), was 1.01 ± 0.05 circ/sec; at low Ca2+ (1.02 ± 0.02 mmol/L), Vcfc fell to 0.89 ± 0.04 circ/sec (P < 0.001 compared with medium); at high Ca2+ (1.68 ± 0.07 mmol/L) Vcfc rose to 1.10 ± 0.03 circ/sec (P < 0.001 compared with medium and low).
Conclusion: Variations in Ca2+ are directly correlated with clinically significant changes in myocardial contractility.
ROBERTO M. LANG, SUSAN K. FELLNER, ALEXANDER NEUMANN, DAVID A. BUSHINSKY, KENNETH M. BOROW. Left Ventricular Contractility Varies Directly with Blood Ionized Calcium. Ann Intern Med. 1988;108:524–529. doi: 10.7326/0003-4819-108-4-524
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Published: Ann Intern Med. 1988;108(4):524-529.
Cardiac Diagnosis and Imaging, Cardiology, Nephrology, Renal Replacement Therapy.
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