Incremental intravenous nitroglycerin for control of afterload during anesthesia in patients undergoing myocardial revascularization.

In 25 patients undergoing coronary artery bypass grafting hemodynamic measurements (including values obtained with Swan-Ganz catheterization in 21 of the patients) were made before and after administering a bolus injection of 64 or 96 mcg of nitroglycerin to relieve intraoperative hypertension. This pharmacological agent reduced afterload and preload without raising heart rate. The effect was apparent within 1-3 min and lasted 5-10 min. Untoward hypotension was not encountered in any instance. This intervention appears to be a safe approach to the treatment of intraoperative hypertension in patients with coronary artery disease.

Hemodynamic assessment of the glutaraldehyde-preserved porcine heterograft in the aortic and mitral positions.

Although glutaraldehyde-preserved porcine heterograft (PH) valves may have a lowered incidence of thromboembolism compared to mechanical valves, data concerning postoperative function in PH valves are incomplete. Accordingly, 26 patients receiving PH in the aortic (AO) or mitral position (MIT) were studied at cardiac postoperative catheterization (mean 19 weeks). The 12 AO patients had an average peak systolic gradient of 19 mm Hg (range 3-52 mm Hg); mean valve area (VA) 1.33 cm2 (0.75-2.5; two patients had postoperative aortic insufficiency. The 14 MIT patients had a mean gradient of 7.9 mm Hg (0-13.1); VA 1.84 cm2 (0.70-3.2; postoperative mitral regurgitation occurred in two patients. AO stent diameter (SD) related to VA, r = 0.85; and peak gradient, r = -0.75. However, MIT SD did not relate to VA or peak gradient. At the 14-month follow-up examination 9 of 11 AO and 7 of 11 MIT patients improved by at least one functional class. Thus, with the advantage of reduced thromboembolism and generally satisfactory valve hemodynamics, further clinical trial of glutaraldehyde-preserved porcine heterografts is justified.

Determination of improved myocardial perfusion after aortocoronary bypass surgery by exercise rubidium-81 scintigraphy.

Practical and noninvasive means are needed for evaluating efficacy of coronary bypass surgery (CBS) in improving blood flow (CBF) to ischemic myocardium in coronary patients. Revascularization was assessed in 15 patients by pre- and post-CBS rest and exercise rubidium-81 myocardial images with a scintillation camera equipped with pinhole collimator and high-energy shield. Ischemic areas were detected by decreased 81Rb activity after exercise compared to rest. Before CBS all patients had exercise angina (EA), positive treadmill ECG (TECG), and abnormal exercise 81Rb scans. After CBS all 15 patients had increased physical activity before angina or completion of treadmill exercise with increased heart rate-blood pressure product (HRBP) (+ 63 +/- 3.2 X 10(2) bpm - mm Hg) in 14 of 15 patients indicating increased CBF; four had positive TECG, and five had EA. The increased HRBP in 14 patients was associated with improved post-CBS exercise 81Rb scans: six had normal patterns while nine were improved with less ischemic patterns. Further, lack of angina and increased exercise tolerance correlated closely with increased 81Rb myocardial perfusion. Thus pre- and postoperative rest and exercise 81Rb scintigraphy gives an accurate, noninvasive, objective approach for evaluation of CBF following CBS and demonstrates the usefulness of this revascularization procedure in coronary patients.

Rapid overdrive pacing of refractory tachyarrhythmias in patients after open-heart surgery.

The efficacy of rapid ventricular pacemaker overdrive in the treatment of supraventricular and ventricular tachyarrhythmias is presented as a new approach to the management of these rhythm disorders inpatients after cardiac surgery. This mode of therapy is exemplified in the control of heart rate and return of normal sinus rhythm in patients with both types of tachyarrhythmias refractory to conventional antiarrhythmic agents. In addition, the pathogenesis and mechanisms of pacemaker overdrive in termination these rhythm disturbances are delineated.

Improvement of reduced left ventricular diastolic compliance in ischemic heart disease after successful coronary artery bypass surgery.

To determine the effects of myocardial revascularization on decreased left ventricular diastolic compliance consequent to chronic stable coronary artery disease, 15 patients with patent coronary artery bypass grafts (Group I) were compared with 8 patients with occluded grafts (Group II) studied before and after operation. In addition, eight normal patients served as controls. Left ventricular diastolic compliance was assessed by: (1) total observed diastolic compliance: stroke volume (V) related to left ventricular diastolic pressure (P) change (deltaV/deltaP) normalized for end-systolic volume; (2) left ventricular stiffness index of passive elastic modulus (a equals slope of deltaP/deltaV related to mean left ventricular diastolic pressure); and (3) fractional pattern of left ventricular filling. All patients had normal sinus rhythm and none had preoperative or postoperative mitral regurgitation. The two groups with coronary disease were well matched preoperatively for ventricular function, volumes, mass, segmental contraction and compliance. Ejection fraction increased in Group I (0.56 preoperatively to 0.65 postoperatively, P less than 0.05) but was unchanged in Group II (0.63 To 0.61, P greater 0.05). Postoperative indexes of left ventricular compliance improved in Group I: (1) 0.110 to 0.150 (P less 0.05); (2) 0.030 TO 0.019 (P less 0.05); and (3) 37 to 30 percent filling during last one third of diastole (P less 0.05). These indexes were unchanged postoperatively in Group II: (1) 0.109 to 0.102 (P greater 0.05); (2) 0.033 to 0.039 (P greater than 0.05); and (3) 36 to 41 percent (P greater 0.05). Compliance indexes were not altered (P greater 0.05) in a subset of seven patients in Group I with preoperative or intercurrent myocardial infarction. Thus, this investigation demonstrates the relatively reversible nature of abnormal left ventricular compliance after successful coronary artery bypass surgery in certain patients with ischemic heart disease.