title: Effect of increasing heart rate in patients with aortic regurgitation. Effect of incremental atrial pacing on scintigraphic, hemodynamic and thermodilution measurements.
abstract: This study was performed to assess the effect of pacing-induced tachycardia in patients with aortic regurgitation. In 12 patients (5 men and 7 women with a mean age of 53 years) with aortic regurgitation, left ventricular end-diastolic and end-systolic volume indexes were measured with multigated equilibrium blood pool imaging, and forward cardiac index was determined with thermodilution, both at rest (mean heart rate +/- standard deviation 72 +/- 8 beats/min) and during atrial pacing at 100 and 120 beats/min. Pacing caused a decremental reduction in left ventricular end-diastolic and end-systolic volume indexes and radionuclide-determined stroke volume index but no change in radionuclide-determined cardiac index or left ventricular ejection fraction. Forward cardiac index increased incrementally from the baseline value at rest to that at 120 beats/min despite a decremental reduction in stroke volume index. There was a stepwise decrease in regurgitant volume/stroke (46 +/- 20 ml/m2 at baseline, 27 +/- 15 at 120 beats/min; p less than 0.05) but no change in regurgitant volume/min (3.38 +/- 1.80 liters/min per m2 at baseline, 3.22 +/- 1.78 at 120 beats/min; difference not significant [NS]) or regurgitant fraction (0.54 +/- 0.13 at baseline, 0.49 +/- 0.13 at 120 beats/min; NS). Mean femoral arterial, pulmonary arterial and pulmonary capillary wedge pressures did not change with pacing.
mesh_terms: D001022:Aortic Valve Insufficiency / Q000175:diagnosis / Q000503:physiopathology*; D001794:Blood Pressure; D006328:Cardiac Catheterization; D002302:Cardiac Output; D002304:Cardiac Pacing, Artificial; D004912:Erythrocytes; D005260:Female; D006321:Heart / Q000000981:diagnostic imaging; D006339:Heart Rate; D006801:Humans; D008297:Male; D008875:Middle Aged; D011877:Radionuclide Imaging; D013670:Sodium Pertechnetate Tc 99m; D013318:Stroke Volume; D013667:Technetium; D013815:Thermodilution
chemical_list: D013667:Technetium; D013670:Sodium Pertechnetate Tc 99m