Prospective randomized trial of OKT3- versus horse antithymocyte globulin-based immunosuppressive prophylaxis in heart transplantation

To compare monoclonal anti-T3-receptor antibody (OKT3) and horse antithymocyte globulin (HATG) immunoprophylaxis, 23 heart transplant recipients were randomized to OKT3 (N = 12) 5 mg IV x 14 days of HATG (N = 11) 5 mg/kg IV x 10 days and followed up for 216 +/- 137 days receiving triple immunosuppression. Recipient groups were demographically and clinically similar. First rejection occurred later in OKT3 recipients vs HATG recipients (31.7 +/- 18.3 vs 15.1 +/- 2.3 days; p less than 0.01), but the first rejection necessitating intensified immunosuppression occurred at similar times (30.9 +/- 14.6 vs 21.9 +/- 10.2 days; NS). Phenotypic characterization of peripheral blood lymphocytes by flow cytometry revealed that OKT3 and HATG recipients had similar decreases in total T lymphocytes and lymphocyte subpopulations. During the follow-up period rejection rates in the OKT3- and in the HATG-treated patients were 3.4 +/- 2.7 and 5.9 +/- 4.7, respectively (NS). The number of rejection episodes per recipient treated with intensified immunosuppression was 1.4 +/- 1.2 in the OKT3- and 2.0 +/- 3.1 in the HATG-treated patients (NS). Infection rates were 4.9 +/- 5.2 in the OKT3- and 2.7 +/- 1.7 in the HATG-treated patients (NS). The number of infection episodes that necessitated intravenous antimicrobial therapy was 2.7 +/- 2.3 in the OKT3- and 1.6 +/- 1.3 in the HATG-treated recipients (NS). The number and length of hospitalizations were similar in patients given OKT3-based or HATG-based immunoprophylaxis. We conclude that immunosuppressive prophylaxis with OKT3 vs HATG in heart transplant recipients is associated with a slightly lower incidence and severity of rejection and slightly higher infection rates.

Cardiac lymphoma associated with superior vena caval syndrome and cardiac tamponade: case history

A sixty-three-year-old patient with malignant histiocytic lymphoma of the heart presented with both superior vena cava syndrome and cardiac tamponade. A two-dimensional echocardiogram showed a large tumor mass in the right atrium and pericardial effusion with right ventricular compression. Superior and inferior vena cavagrams disclosed a lobulated tumor located in the right atrium that extended into and obstructed the superior vena cava. After the pericardial effusion was drained and the diagnosis was established, the patient was irradiated and given chemotherapy with resolution of the tamponade and superior vena cava obstruction.

Risk of thromboembolism during diagnostic and interventional cardiac procedures with nonionic contrast media

To investigate the relationship between clot formation and thromboembolism, canine blood was withdrawn into catheter-syringe or catheter-steerable wire systems containing either contrast medium or normal saline as used in debubbling techniques. The contrast media used were iohexol, iopamidol, ioxaglate, and diatrizoate. Without the use of heparin, after a 30-minute incubation, blood clots were harvested from all catheter-syringe systems except those with diatrizoate and from all catheter-steerable wire systems. Significantly more blood clot was harvested from the catheter-steerable wire system. With use of heparinized blood, no clot was found in any system. Twelve dogs that underwent coronary angiography were divided into two groups; one received heparin (5,000 IU) and the other did not. Thromboembolism occurred in all nonheparinized dogs that underwent angiography with iohexol or iopamidol but not in any other group. The authors found that in a dog model nonionic contrast media are more thrombogenic than ionic contrast media, especially in the catheter-steerable wire system. The blood clot in the catheters is associated with thromboembolism during angiography. The authors maintain that in this setting, blood clotting and thromboembolism with nonionic agents can be eliminated with heparin.

Effects of ionic and nonionic contrast media on bradyarrhythmia during coronary angiography: a comparison of Renografin-76, Hypaque-76, and Isovue-370

Contrast media occasionally produce bradyarrhythmias defined as a 25% decrease in heart rate and/or developing atrioventricular block during coronary angiography. Twelve left coronary angiographies and seven right coronary angiographies were performed with 10 ml of diatrizoate meglumine and diatrizoate sodium (Renografin-76 [R76] or Hypaque [H76]) or iopamidol (Isovue 370 [ISO]) in a blinded randomized fashion. Heart rate decreased significantly from 135 +/- 5 to 120 +/- 5 beats/min (p less than 0.001) with R76, to 127 +/- 7 beats/min (p less than 0.01) with H76, and to 130 +/- 6 beats/min (p less than 0.05) with ISO in left coronary angiographies; more profound decrease was observed in right coronary angiographies from 134 +/- 4 to 87 +/- 18 beats/min (p less than 0.001) with R76, to 99 +/- 14 beats/min (p less than 0.001) with H76, and to 125 +/- 7 beats/min (p less than 0.01) with ISO. In 12 left coronary angiographies bradyarrhythmia was observed in five cases with R76, two with H76, and none with ISO. In seven right coronary angiographies it occurred in six with R76, three with H76, and none with ISO. The differences in the incidence of bradyarrhythmia between R76 and ISO were significant during left and right coronary angiographies (p less than 0.05 and p less than 0.01, respectively). Thus ionic contrast media produced more marked bradyarrhythmias than nonionic contrast media in coronary angiography, especially R76. Right coronary angiography resulted in more profound bradyarrhythmias than left coronary angiographies. This study suggested that nonionic contrast media (ISO) might be preferable to ionic contrast media (R76 or H76) for coronary arteriography.

Catecholamine sensitive right ventricular outflow tract tachycardia: intraoperative mapping and ablation of a free-wall focus

A patient with catecholamine-sensitive right ventricular outflow tract tachycardia refractory to pharmacological therapy underwent intraoperative mapping and cryoablation. Epicardial and endocardial mapping demonstrated earliest ventricular activation in the free-wall of the outflow tract, and cryoablation of the area resulted in surgical cure. No histologic abnormalities at the site of tachycardia origin were detected. Catecholamine sensitivity does not appear to result from a diffuse myocardial process, and permanent ablation of the tachycardia in this group of patients with a regional procedure is feasible.

The mechanism and significance of ventricularization of intracoronary pressure during coronary angiography

Ventricularization of pressure during coronary angiography has been said to identify the presence of left main coronary artery disease, but the hemodynamic features and the mechanism of this process have not been studied. Twenty consecutive patients with ventricularization were identified prospectively in our laboratory. Four patients had a discrete ostial left main stenosis and 16 patients had stenosis of the entire length of the left main coronary artery. The degree of pressure drop upon cannulation of the diseased left main coronary artery was highly variable; the systolic pressure decreased by 9 to 94 mm Hg, and the diastolic pressure decreased by 6 to 60 mm Hg. The morphology of the ventricularized pressure was distinct. It had a presystolic deflection resembling an a wave. The upstroke of this waveform was slower and the downstroke was steeper than that of the aortic pressure. An identical waveform was observed in dogs after partial occlusion of the left main coronary artery with a balloon-tipped catheter. The waveform of the so-called ventricularized pressure is derived from the aortic pressure, which is altered by its transmission across the left main coronary stenosis. The appearance of ventricularization is an important clue to the presence of left main coronary artery disease.

Predictors of late acute orthotopic heart transplant rejection

To identify predictors of late acute rejection after orthotopic heart transplantation (OHT), 53 patients who received transplants between March 1984 and March 1987 and who survived at least 1 year postoperatively were followed up for 402-1,151 days (mean, 841 days). Fourteen patients experienced 22 moderate or severe rejection episodes more than 1 year after OHT (LR); 39 were nonrejectors (NR). Twelve of 14 (86%) LR and only 14 of 39 (36%) NR had two or more moderate or severe rejection episodes within the first year after OHT (p less than 0.001). The LR had significantly higher numbers of infections more than 1 year after OHT (2.0 vs. 0.9; p less than 0.05). Nine of 22 (40%) late acute rejection episodes followed within 1 month of infection. Human leukocyte antigen reactivity before OHT, follow-up hemodynamics, length of survival, incidence of diabetes mellitus, coronary artery disease 1 year after OHT, mean cyclosporine levels, and mean daily prednisone doses were similar in LR and NR patients. We conclude that 1) OHT recipients with two or more moderate or severe rejection episodes in the first year after OHT are at higher risk of developing late acute rejection and may require closer long-term rejection surveillance and more aggressive maintenance immunosuppression and 2) the possible relation between infection and subsequent acute rejection episodes in OHT recipients requires further investigation.

Placement of intra-aortic balloon pump allows definitive biliary surgery in patients with severe cardiac disease

This study reviews the cases of 15 patients with severe cardiac disease treated with the intra-aortic balloon pump (IABP) to improve cardiac status so that they could undergo definitive cholecystectomy. The 14 men and one woman ranged in age from 49 to 74 years. Indications for cholecystectomy included acute cholecystitis in nine patients and chronic cholecystitis in six patients. All patients had prior myocardial infarction, and in two patients this had occurred within 2 months of operation. All patients were Goldman's Class IV. Eight had severe cardiomyopathy. Mean ventricular ejection fraction was 21% +/- 3%. Cardiac index was 2.2 +/- 0.2 L/m/m2, and pulmonary artery pressure (PAP) was 51 +/- 5/23 +/- 2 mm Hg. After IABP placement, pulmonary wedge pressure decreased in all patients, from 24 +/- 3 mm Hg to 16 +/- 2 mm Hg (p less than 0.01). PAP systolic pressure decreased to 38 +/- 3 mm Hg (p less than 0.01), and PAP diastolic pressure decreased to 18 +/- 2 mm Hg (p less than 0.05). All patients had cholecystectomy. Five patients had intraoperative cholangiography. One of these five patients had a common bile duct exploration, and another underwent cystgastrostomy. Two patients died postoperatively of arrhythmias. Thirteen patients are alive 3 months to 7 years after operation, without biliary symptoms. Three patients have had orthotopic heart transplants. We conclude that IABP significantly improves cardiac performance so that many patients who have severe cardiac disease can undergo definitive biliary surgery.

Constrictive pericarditis after cardiac surgery

Forty-five patients were identified as having constrictive pericarditis after cardiac surgery. The mean patient age was 61 years (range, 40 to 77 years). Twenty-three of 37 patients with adequate clinical information were reported to have had a diagnosis of postpericardiotomy syndrome after the original surgery. The mean interval from original surgery to presentation with constriction was 23.4 months (range, 1 to 204 months). Computerized tomography was helpful in establishing a diagnosis of constriction in 23 of 29 patients (79%). Bypass graft patency was 93% (85 of 91 grafts). Severe pulmonary hypertension (pulmonary artery systolic pressure greater than or equal to 60 mm Hg) was present in nine patients; 8 had coexistent valvular disease (seven cases of mitral valve disease, and aortic valve disease in one). Thirty-seven of the 45 patients underwent pericardial stripping, 28 of whom experienced marked symptomatic improvement. One patient had persistent right heart failure, which was not documented to be secondary to constriction. Four patients had persistent constrictive physiologic conditions. Three of these patients had more extensive pericardial stripping and showed clinical improvement. Four patients (11%) died within 30 days of stripping. Eight patients received medical therapy alone. The decision to treat patients medically was based either on favorable response to medical therapy (five patients), or poor general clinical status.

Adrenergic influences on ischemic and reperfusion arrhythmias in a canine model with diminished collateral blood flow

To examine the role of adrenergic influences on genesis of ischemic and reperfusion arrhythmias, the left anterior descending coronary artery (LAD) was cannulated and perfused by a shunt from the left carotid artery in 38 open-chest pentobarbital-anesthetized dogs. Ischemia was produced by shunt occlusion and retrograde diversion of collateral flow from the LAD. The diverted blood was collected and returned to the animal by intravenous (i.v.) injection. The shunt was opened and the ischemic myocardium reperfused after 30 min of ischemia. Microsphere injections in six dogs during shunt occlusion and retrograde bleeding showed that blood flow to the ischemic zone was less than 1.5% of normal zone flow. The remaining 32 dogs were randomized into four treatment groups. Dogs (n = 8) were treated before shunt occlusion with either saline, nadolol (1 mg/kg), prazosin (0.2 mg/kg), or bilateral stellate transection. As compared with saline treatment, nadolol and stellate transection significantly reduced heart rate (HR), and prazosin significantly reduced mean arterial blood pressure (MAP) (p less than 0.05). However, none of the antiadrenergic interventions significantly reduced the number or frequency of ectopic beats during either the 1a or 1b phases of ischemia. None of the 32 dogs developed ventricular fibrillation (VF) during ischemia, but all dogs fibrillated within 30 s of reperfusion. The size of the ischemic zone ranged from 21 to 38% of the left ventricle, and there were no differences among the four treatment groups. The results suggest that when ischemia is severe, the adrenergic nervous system does not play a significant role in genesis of ischemic-induced ectopy or reperfusion-induced VF.

Long-term follow-up of heart transplant recipients treated with murine antihuman mature T cell monoclonal antibody (OKT3): the Loyola experience

We describe the long-term follow-up of 25 patients treated with murine antihuman mature T cell (OKT3) monoclonal antibody at Loyola University Medical Center. After OKT3 rescue therapy, 12 patients were monitored for 16.5 +/- 6.5 months. Twenty-two moderate and three severe rejection episodes occurred 11 to 469 days (166.8 +/- 126.0) after OKT3 therapy in nine of 12 patients. During the follow-up period three patients died, and one required retransplantation because of recurrent rejection. The coronary arteries of three failed allografts had severe intimal thickening and infiltration with lymphocytes. Thirteen patients received OKT3 for prophylactic immunosuppression, and their course was compared to that of 13 patients who underwent transplantation during the same period but were given prophylactic horse antihuman thymocyte globulins (HATG). There were no differences between the two drugs with respect to long-term incidence and severity of rejection and infection, cardiac allograft function, and survival. Our results indicate that, despite successful reversal with OKT3, heart transplant recipients with refractory rejection remain plagued by recurrent rejection. Cardiac allografts in recipients who die as a result of recurrent rejection show evidence of immune-mediated vasculitis, which results in severe and diffuse coronary luminal narrowing. OKT3 and HATG appear to be equally effective for rejection prophylaxis.

Long term survival of class IV heart failure patients treated with oral amrinone

The purpose of this study was to evaluate the effect of amrinone on the survival of a group of 51 Class IV congestive heart failure patients as well as changes in exercise capacity, hemodynamics, and clinical status. In those 22 patients able to exercise before treatment with amrinone, exercise duration increased from 4.15 minutes to 6.58 minutes on the treadmill. In those 19 patients first treated with intravenous amrinone, there was an increase in cardiac index from 1.9 to 2.6 L/min/m2. Thirty seven patients (72%) died in the follow-up period, most in the first four months. In this group of Class IV heart failure patients, there were two subsets of patients: one with a stable course (Group I) and one with a malignant course (Group II). The Group II patients accounted for much of the mortality in the follow-up. Patients with coronary artery disease did worse than patients with idiopathic dilated cardiomyopathies. There was no evidence that amrinone shortened or prolonged the survival of these Class IV patients.

Hemodynamic abnormalities during coronary angiography: comparison of Hypaque-76, Hexabrix, and Omnipaque-350

The hemodynamic effects induced by coronary angiography in dogs with low osmolar ionic dimer Hexabrix (HB) and nonionic Omnipaque-350 (OM) were compared to the standard ionic contrast medium, Hypaque-76 (H76), both in the normal heart and in one with simulated severe cardiac disease. Left coronary angiography was performed in 12 "normal" closed-chest dogs with 10-cc injections of H76, HB, and OM in a randomized, blinded fashion. The maximal change in the left ventricular (LV) systolic pressure (SP), mean aortic pressure (MAP), left ventricular end diastolic pressure (LVEDP), and LV dp/dt were recorded. The LVSP and MAP fell 30 +/- 3 mm Hg and 26 +/- 4 mm Hg with H76, 22 +/- 2 mm Hg and 19 +/- 2 mm Hg with HB, and 7 +/- 1.5 mm Hg and 5 +/- 1 mm Hg with OM (P less than .001). The LVEDP increased 4.8 +/- 0.5 mm Hg with H76, 3 +/- 0.5 mm Hg with HB, but only 0.2 mm Hg with OM (P less than .001). The LV dp/dt decreased 392 +/- 63 mm Hg/sec with H76 and 235 +/- 21 mm Hg/sec with HB, but increased 411 +/- 50 mm Hg with OM (P less than .001). In eight additional open-chest dogs, left coronary angiography was performed 1 hr after occlusion of the proximal LAD coronary artery and in the presence of a critical circumflex coronary artery (CX) stenosis.(ABSTRACT TRUNCATED AT 250 WORDS)

The potential risk of thrombosis during coronary angiography using nonionic contrast media

The influence of contrast media on coagulation has an important association with thromboembolic complication during coronary angiography. In this study, whole blood was methodically mixed with nonionic contrast medium, Iohexol (IOH), conventional ionic contrast medium, Hypaque-76 (H76), and low osmolar ionic dimer Hexabrix (HB) in vitro. The thrombotic propensity of contrast agents can be evaluated by measuring the clot formation of the mixtures. The experiments were repeated with whole blood after systemic heparinization. In the in vitro study, 5 ml of canine (N = 10) and 3 ml of human (N = 11) whole blood was incubated for 30 min in glass tubes with equal volumes of IOH, H76, HB, and 0.9% NaCl before heparinization. Clot formation with IOH and 0.9% NaCl were seen both in dogs (4.0 +/- 0.7 gm and 5.6 +/- 0.8 gm) and in patients (1.4 +/- 0.9 gm and 2.9 +/- 1.3 gm), whereas no clot was seen with H76 or XB. Following heparinization, no clot was visualized in any mixture of whole blood with contrast media or 0.9% NaCl. Similar results were observed in the catheter-syringe system with canine blood (N = 11) mixed with the contrast agents. Blood clots found in 15 min and 30 min of IOH were 0.07 +/- 0.08 gm and 0.44 +/- 0.20 gm (P less than 0.01) and of NaCl were 0.29 +/- 0.37 gm and 0.69 +/- 0.38 gm (P less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Pacing lead fracture after a deceleration injury

Acute pacemaker malfunction is potentially lethal. A high index of suspicion must be maintained in physicians caring for traumatized patients utilizing permanent pacing systems. We present a case of transvenous pacemaker lead fracture sustained in a vehicular deceleration injury.

Coronary revascularization and implantation of the automatic cardioverter/defibrillator: reliability of immediate intraoperative testing

Concomitant coronary revascularization and implantation of the automatic cardioverter/defibrillator is an increasingly common procedure. To determine whether cardioversion/defibrillation thresholds measured after weaning patients from cardiopulmonary bypass are sufficient to justify immediate implantation of the pulse generator, we prospectively compared postpump values to those obtained 1 week later in five patients. R-wave amplitudes during both sinus rhythm and ventricular tachycardia, lead impedance, defibrillation thresholds and cardioversion thresholds remained stable or improved from the postpump to the 1 week values. Five other patients had the generator implanted at the time of revascularization. Immediate postbypass cardioversion thresholds (mean 10 +/- 8 joules) in these ten patients did not significantly differ from those of 20 nonpump implantations (VT mean 7 +/- joules; VF 15 +/- 4 joules and defibrillation thresholds mean 17 +/- 6 joules). These findings suggest that the residual effects of cardioplegia, core-cooling and operative ischemia have no significant effects on intraoperative testing of implanted defibrillators. This clinical experience supports the practice of immediate implantation of the pulse generator at the time of revascularization.

Safety and efficacy of esmolol for unstable angina pectoris

Esmolol is a rapidly metabolized cardioselective beta-adrenergic blocker that provides steady state beta-adrenergic blockade when administered by continuous intravenous infusion. To determine the efficacy of esmolol in the management of unstable angina, 23 patients with known coronary artery disease, who averaged 3.7 +/- 2.7 daily episodes of chest pain at rest, were randomized to receive either a continuous infusion of esmolol (n = 12) or oral propranolol (n = 11), as an adjunct to concomitant antianginal therapy. Patients with systolic blood pressure less than 110 mm Hg, heart rate less than 60 beats/min or known contraindications to beta blockade were excluded. Esmolol was titrated in a step-wise fashion from 2 to 24 mg/min at 5-minute intervals up to a 30% reduction in heart rate and systolic blood pressure double-product. The propranolol dose was increased every 6 hours by 50 to 100% to achieve a similar reduction in heart rate and blood pressure. When compared with their 24-hour baseline periods, both groups achieved a significant reduction in episodes of chest pain, from 4.6 +/- 3.3 to 1.4 +/- 1.5 in the esmolol group (p less than 0.02) and 2.6 +/- 1.4 to 1.0 +/- 1.5 in the propranolol group (p less than 0.02) during the subsequent study period. The cardiac event rate and incidence of drug side effects were similar between the 2 groups; however, side effects seen with esmolol did not require treatment after drug discontinuation. Thus, maximally tolerated beta blockade is an effective therapy for unstable angina.(ABSTRACT TRUNCATED AT 250 WORDS)

The duration of coronary occlusion influences adrenergic contributions to reperfusion ventricular arrhythmias

To study the role of the adrenergic nervous system in the genesis of nonlethal reperfusion arrhythmias, the proximal left anterior descending coronary artery was occluded for either 1 or 3 hours in 48 open-chest dogs anesthetized with alpha-chloralose. Heart rate was controlled (90 to 110 beats/min) by bilateral vagotomy and continuous right vagal stimulation. Dogs were treated with either saline, timolol (0.1 mg/kg), or prazosin (0.5 mg/kg) 15 minutes prior to reperfusion. Reperfusion after 1 hour of occlusion in saline-treated dogs evoked sustained polymorphic ventricular tachycardia (204 +/- 9 beats/min) that reverted to sinus rhythm by 15 minutes of reperfusion. The maximum rate of ventricular tachycardia was significantly reduced by both prazosin and timolol. Both drugs also caused about a 50% reduction in the total number of ectopic beats in the first 10 minutes of reperfusion. With a 3-hour occlusion, reperfusion in saline-treated dogs caused sustained polymorphic ventricular tachycardia (135 +/- 15 beats/min) which persisted for several hours. Neither timolol nor prazosin significantly altered the ventricular ectopic rate in these dogs. Furthermore, bilateral stellate transection, left stellate stimulation, isoproterenol (0.5 mg/kg), or methoxamine (100 ug/kg) all failed to alter the ventricular ectopic rate in the saline-treated dogs. Ventricular ectopy induced by reperfusion after a 1- or 3-hour occlusion was overdriven in all dogs by rapid atrial pacing. The results suggest that the nature of reperfusion-induced ventricular ectopy is highly dependent upon the preceeding duration of coronary occlusion.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of contrast media on the conducting system of the heart during coronary angiography. A comparison of Renografin-76 to Hypaque-76

Electrocardiographic changes induced by ionic contrast media can cause complications during coronary angiography. A conduction delay through various parts of the heart is one factor in the genesis of asystole or ventricular fibrillation. Hypaque-76 (H76) and Renografin-76 (R76) are nearly identical ionic contrast media except that R76 binds more calcium than H76 because of the presence of sodium citrate and EDTA in R76. To determine whether the calcium binding additives in ionic contrast media contribute to the cardiac conduction abnormalities, we examined conduction time through the atrioventricular (AV) nodal tissue (via bipolar His bundle electrograms) and through the distal part of the conduction system (recording the QRS complex from the ECG) during coronary angiography. We injected 10 mL of H76 and R76 in 19 closed chest dogs in a blinded, randomized fashion during coronary angiography. The effects of H76 and R76 on heart rate, AH interval, HV interval, V interval and PR interval, and QRS complex duration were recorded. In 14 nonatrial pacing dogs, compared with H76, R76 produced a greater increase in the AV interval (32.9 +/- 6 milliseconds vs 12.4 +/- 2 milliseconds, P less than .01) and the PR interval (29.6 +/- 6 milliseconds vs 11.9 +/- 4 milliseconds, P less than .02). Additionally, the heart rate decreased 13.9 +/- 3.5 beats/minute from control with R76 compared with a decrease of 4.2 +/- 2.6 beats/minute from control with H76 (P less than .05). There was no significant difference between the prolongation of the HV interval and V interval, or QRS complex duration generated by R76 and H76.(ABSTRACT TRUNCATED AT 250 WORDS)

Coronary angiography during acute myocardial infarction in dogs: comparison of the hemodynamic effects of ionic and nonionic contrast media

We compared the hemodynamic effects during coronary angiography of three nonionic contrast media, iopamidol, iohexol, and ioversol, with each other as well as with the standard ionic contrast medium containing 66% diatrizoate meglumine and 10% diatrizoate sodium (Hypaque-76) in the presence of a left anterior descending coronary artery occlusion in dogs. In 13 opened-chest anesthetized dogs, we recorded the maximal change in left ventricular systolic pressure (LVSP), mean aortic pressure (MAP), left ventricular diastolic pressure (LVDP) and rate of rise in left ventricular pressure (LV dp/dt) during left main coronary artery injections of 10 ml each of Hypaque-76, iopamidol, iohexol, and loversal 1 hour after left anterior descending coronary artery occlusion. The changes in LVSP and MAP were, respectively, -29 +/- 12 mm Hg and -21 +/- 11 mm Hg with Hypaque-76, 3 +/- 6.6 mm Hg and -0.2 +/- 3.6 mm Hg with iopamidol, 4.8 +/- 8.6 mm Hg and 0.5 +/- 4 mm Hg with iohexol, and -0.8 +/- 6 mm Hg and -1.5 +/- 33 mm Hg with ioversal (p less than 0.001). The change in LVDP was 5.4 +/- 4.4 mm Hg with Hypaque-76 but -1.5 +/- 3.1 mm Hg with iopamidol, -1.7 +/- 2.4 mm Hg with iohexol, and -0.5 +/- 2.5 mm Hg with ioversol (p less than 0.001). The LV dp/dt decreased 682 +/- 318 mm Hg/sec with Hypaque-76, but increased 412 +/- 297 mm Hg/sec with iopamidol, 350 +/- 214 mm Hg/sec with iohexol, and 293 +/- 191 mm Hg/sec with ioversol (p less than 0.001). Thus, each nonionic agent produced significantly fewer hemodynamic abnormalities than Hypaque-76. There was no significant difference between any of the nonionic agents on any hemodynamic parameter. These agents may be preferable in patients with acute myocardial infarction or significantly impaired myocardial function.

Comparison of the effects of acute and chronic beta-blockade on infarct size in the dog after circumflex occlusion

In order to compare the effects of acute and chronic beta-blockade on infact size, the left circumflex coronary artery was occluded for 6 hours in 33 anesthetized dogs. The dogs (18 to 22 kg) were divided into three groups; group 1 (N = 10) served as controls, group 2 received intravenous nadolol (average dose 1.25 mg/kg) just prior to coronary occlusion, and group 3 received oral nadolol (80 mg) twice daily for 16 days prior to coronary occlusion. To ensure equivalent degrees of beta-blockade at the time of occlusion, group 2 and 3 dogs were given incremental doses of intravenous nadolol to abolish the chronotropic response to isoproterenol (2 mu/kg IV). Left ventricular pressure, its first derivative (dP/dt), and heart rate were monitored. The anatomic risk region was determined antemortem by Evan's blue staining while the infarct zone was delineated postmortem by tetrazolium staining. Compared to Group 1, heart rate was 22% lower in group 2 and 15% lower in group 3 dogs 6 hours after occlusion (p less than 0.05). There were no differences among groups in peak left ventricular systolic pressure or mean arterial pressure. Infarct size as a function of the area at risk was 68 +/- 3% in group 1, 52 +/- 7% in group 2, and 44 +/- 8% in group 3. A significant difference was found only between groups 3 and 1. The data suggest that chronic beta-blockade provides greater protection against ischemic-induced necrosis than does acute beta-blockade. The greater protective effect of chronic beta-blockade may be due to chronic adaptive changes in either blood flow or metabolism.

The effects of rapid volume expansion on the right and left cardiac filling pressures after coronary artery bypass surgery

Rapid volume expansion is a diagnostic procedure which can reveal typical hemodynamics of pericardial constriction in patients with pericardial disease who have normal hemodynamics in their baseline state. We studied 20 patients with previous coronary artery bypass surgery in order to determine whether this operation results in some degree of pericardial constriction which could be demonstrated by rapid volume expansion. After infusing 1 L of physiologic saline solution over six minutes, the right atrial pressure increased by 5 +/- 2 mm Hg, the right ventricular diastolic pressure by 4 +/- 3 mm Hg, the pulmonary capillary wedge pressure by 7 +/- 3 mm Hg, and the left ventricular diastolic pressure by 7 +/- 4 mm Hg (mean +/- SD). Equalization of the left and right cardiac pressures was not observed, and the normal respiratory variation of the pressures was not altered by rapid volume expansion. Thus, the pericardial manipulation associated with the performance of coronary artery bypass surgery does not commonly result in the development of subclinical pericardial constriction.

Contrast media-induced ventricular fibrillation. A comparison of Hypaque-76, Hexabrix, and Omnipaque

Contrast media occasionally produce ventricular fibrillation during coronary angiography. We compared the fibrillatory propensity of the conventional ionic contrast medium, Hypaque-76 (H76) to the low osmolar ionic dimer Hexabrix (HB) and to the nonionic agent Omnipaque (OM) in 20 open chest anesthetized dogs. Intracoronary injection of 6 mL of contrast medium produced spontaneous ventricular fibrillation in four of ten dogs with H76, compared with two of ten with HB, and zero of ten with OM (P = .07). The induction of two premature beats by programmed stimulation of the myocardium during injection of 4 mL of contrast medium produced ventricular fibrillation in ten of ten dogs with H76, compared with three of ten with HB, and zero of ten with OM (P less than .001). Both H76 and HB produced ventricular fibrillation in ten of ten dogs when three premature beats were induced, compared with two of ten dogs with OM (P less than .001). Four mL H76 produced a 109 +/- 18 msec increase in the QT interval, compared with an 82 +/- 17 msec increase with HB, and a 45 +/- 12 msec increase with OM. We conclude that both low osmolar HB and OM are less fibrillatory than the conventional ionic medium H76, and that the nonionic medium OM is less fibrillatory than the ionic dimer contrast medium HB.