ABSTRACT
We hypothesized that pacing at sites other than the right ventricular (RV) apex or at two or more ventricular sites would activate the myocardium more rapidly and improve cardiac function in patients undergoing coronary revascularization or aortic valve replacement. Epicardial electrodes were placed on the right atrium (A), RV paraseptal area close to the RV apex (B), RV outflow tract (C), LV apex (D), in patients undergoing bypass surgery. At constant rate and AV delay, we measured CO during A pacing, DVI pacing at B, C, D, and various combinations of sites in random order in ten patients with EF > 50% and 27 patients with EF < or = 50%. When pacing at two sites, we made one electrode a cathode and one an anode and noted two distinct thresholds by careful observation of the 12-lead ECG. There were no significant differences in CO, systemic vascular resistance, systolic, or mean arterial pressure. Significant differences were noted in QRS duration, which increased progressively going from AAI to 3-site, 2-site, and single site pacing (P < 0.05 each comparison). Thus: (1) QRS duration correlated inversely with the number of ventricular sites paced; (2) despite this, CO did not improve irrespective of baseline EF; (3) multisite pacing produced multiple distinct thresholds which appeared to be related to the number of sites paced, and (4) unique ECG patterns confirmed multisite pacing.
Subject(s)
Aortic Valve/surgery , Cardiac Pacing, Artificial , Electrocardiography , Heart Valve Prosthesis Implantation , Hemodynamics/physiology , Myocardial Revascularization , Postoperative Complications/therapy , Cardiac Output/physiology , Electrodes , Heart Rate/physiology , Humans , Postoperative Complications/physiopathology , Prospective Studies , Systole/physiology , Treatment Outcome , Ventricular Function, Left/physiologyABSTRACT
A 62-year old patient was admitted with a 24-hour history of ischemia in both legs caused by acute distal aortic occlusion and had had a total loss of sensitivity and motor function for 8 hours. Preoperative serum creatine phosphokinase level was 10,900 IU/ml. During aortofemoral reconstruction, both limbs were reperfused with a potassium-free, blood-cardioplegia-like perfusate. Fasciotomies were not necessary. After operation, maximal serum creatine phosphokinase levels remained below 10,000 IU/ml. Limb sensitivity and motor function were normal. Even for prolonged acute aortoiliac occlusion, a simplified controlled limb-reperfusion may preserve skeletal muscle and nerve function and prevent local and systemic complications caused by reperfusion damage.
