Bypass surgery versus stenting for the treatment of multivessel disease in patients with unstable angina compared with stable angina.

BACKGROUND: Earlier reports have shown that the outcome of balloon angioplasty or bypass surgery in unstable angina is less favorable than in stable angina. Recent improvements in percutaneous treatment (stent implantation) and bypass surgery (arterial grafts) warrant reevaluation of the relative merits of either technique in treatment of unstable angina. Methods and Results- Seven hundred fifty-five patients with stable angina were randomly assigned to coronary stenting (374) or bypass surgery (381), and 450 patients with unstable angina were randomly assigned to coronary stenting (226) or bypass surgery (224). All patients had multivessel disease considered to be equally treatable by either technique. Freedom from major adverse events, including death, myocardial infarction, and cerebrovascular events, at 1 year was not different in unstable patients (91.2% versus 88.9%) and stable patients (90.4% versus 92.6%) treated, respectively, with coronary stenting or bypass surgery. Freedom from repeat revascularization at 1 year was similar in unstable and stable angina treated with stenting (79.2% versus 78.9%) or bypass surgery (96.3% versus 96%) but was significantly higher in both unstable and stable patients treated with stenting (16.8% versus 16.9%) compared with bypass surgery (3.6% versus 3.5%). Neither the difference in costs between stented or bypassed stable or unstable angina ($2594 versus $3627) nor the cost-effectiveness was significantly different at 1 year. CONCLUSIONS: There was no difference in rates of death, myocardial infarction, and cerebrovascular event at 1 year in patients with unstable angina and multivessel disease treated with either stented angioplasty or bypass surgery compared with patients with stable angina. The rate of repeat revascularization of both unstable and stable angina was significantly higher in patients with stents.

Current status of sensor-modulated rate-adaptive cardiac pacing.

In one third of patients requiring permanent cardiac pacing, sinoatrial response to exercise is inadequate. This has led to the development of a number of nonatrial sensors capable of increasing stimulation rate in response to metabolic demand. Initial sensor-modulated pacemakers were designed for use in the ventricle. This review was undertaken to compare ventricular rate-adaptive pacing with dual chamber and nonrate-adaptive atrial modes. Rate-adaptive ventricular pacing is primarily indicated in patients with complete heart block and nonfunctional atria in whom increased rates are not associated with the development of myocardial ischemia or retrograde conduction. A responsive atrium remains the best measure of metabolic demand, and devices capable of maintaining atrioventricular (AV) sequencing provide superior hemodynamic performance at usual activity levels. In addition, preserved AV relations reduce the incidence of new atrial fibrillation and stroke. Newer devices combining the advantages of atrial and nonatrial rate modulation with the preservation of AV synchrony will best utilize the developing sensor technologies.

Rechargeable silver-modified mercuric oxide-zinc cell for cardiac pacemakers.

Tests were conducted on rechargeable mercury-zinc pacemaker batteries under simulated and actual biologic conditions, using a variety of discharge rates and charging schedules. In tests on 96 cells at a 6.4 milliampere (ma) discharge, recharging once every 15 months of simulated pacing at a 25 microampere (mua) drain, the earliest cell failure occurred after an equivalent of 50 years of pacing. The mean pacing equivalent for all 96 cells was more than 140 years. In 6.4 ma discharge tests on 24 cells, recharging once every 8 days of simulated pacing, only 1 cell in 24 failed after an equivalent of more than 500 years of pacing (actual time 2 years). In tests on 13 cells pacing at a 200 mua drain without recharging, the simulated mean duration of pacing before total discharge was 4.8 years. Seven other cells at a 200 mua drain with periodic recharging continue to function normally after more than 7 years of actual time, simulating 56 years of pacing at a 25 mua drain. Cardiac pacemakers using the rechargeable mercury-zinc cell have been implanted in animals for more than 2 1/2 years and in patients for more than 1 year with all units continuing to function satisfactorily. It has been demonstrated unequivocally that a rechargeable mercury-zinc pacemaker will function continuously for more than 4 years without recharging and that periodic recharging will extend pacing life far beyond that predicted for lithium and nuclear primary power sources.

The non-hermetically sealed pacemaker myth, or, Navy-Ribicoff 22,000-FDA-Weinberger o.

Although the Secretary of Health, Education and Welfare recently stated that hermetic sealing of all implanted cardiac pacemakers, as recommended by the Navy in 1969, is inadvisable, several small manufacturers are already marketing hermetically sealed devices (CPI, Pacesetter), all of the over 600 nuclear pacers implanted to date have been hermetically sealed, and belatedly the major manufacturers are developing hermetically sealed units. Total hermetic sealing of all implantable electronic devices has been technically feasible for years, and it is essential that device legislation include mandatory encapsulation standards.

Diagnostic and therapeutic challenges following the cytologic diagnosis of in situ carcinoma of the lung.

Clinical challenges associated with the cytologic detection of eight cases of occult pulmonary carcinoma are presented. The pulmonary lesions were successfully localized and resected in three of six cases encountered since the availability of flexible fiberoptic bronchoscopy and selective bronchial brushing. Two of the resected neoplasms were unequivocally in situ, while preoperative radiotherapy precluded accurate pathologic determination of invasiveness in the third. The reported experience with unequivocal in situ bronchogenic carcinoma localized and treated surgically prior to invasion through the basement membrane now totals 17 cases (15 previously reported). Forty-four additional cases (43 previously reported) have been localized and resected following early invasion. From this group totaling 61 occult carcinomas, only two patients (3 percent) are known to have died of pulmonary carcinoma during a followup ranging from 2 to 20 years.

Management of massive hemoptysis secondary to catheter-induced perforation of the pulmonary artery during cardiopulmonary bypass.

Pulmonary artery perforation by flow-directed catheters is associated with high mortality, particularly in heparinized patients. We report a recent case and discuss recognition and management.

Effects of acid-base imbalance on myocardial pacing thresholds.

The effects of acid-base imbalance on ventricular pacing thresholds were studied in anesthetized dogs with complete heart block with the use of an oscilloscope and current probe. Acidosis (base excess-15) and alkalosis (base excess + 15)both resulted in significant increases in threshold voltage and current requirements at all stimulus durations tested. Chronaxie, however, was not significantly affected by shifts in acid-base balance. Abnormalities of acid-base status may adversely affect the accuracy of threshold values obtained during evaluation of different electrode designs and during electrodes implantation for clinical cardiac pacing.

Runaway pump head: new cause of gas embolism during cardiopulmonary bypass.

Massive gas embolism was narrowly avoided during a recent case of cardiopulmonary bypass for aortic valve replacement. Cause of the mishap was an arterial pump head that had rapidly accelerated spontaneously, emptying the oxygenator of blood within seconds. No gas entered the patient's vascular system, but a period of circulatory arrest was required in order to purge the extracorporeal circuit of gas and to re-establish blood flow. Only an instantaneous response by the perfusionist prevented massive gas embolism.

Symptomatic deep venous thrombosis of the arm associated with permanent transvenous pacing electrodes.

From October 1970 to May 1977, a total of 212 pacemakers were implanted at the Milton S. Hershey Medical Center of Pennsylvania State University, Hershey. During this period, we encountered five patients with symptomatic thrombosis of the subclavian vein, a rate for this complication of approximately 2 percent. Although this complication was reported only rarely prior to 1976, we believe that symptomatic subclavian thrombosis after insertion of a transvenous pacemaker electrode occurs more frequently than previously suspected. The etiology, pathogenesis, and treatment of this interesting condition are discussed.

The mechanism of myocardial protection from ischemic arrest by intracoronary tetrodotoxin administration.

Intracoronary injection of 14 mcg. of tetrodotoxin into the ischemic isolated rat heart resulted in immediate cessation of mechanical activity. Upon reperfusion with oxygenated, modified Krebs-Henseleit bicarbonate buffer in a modified Langendorff apparatus, all hearts recovered normal rate, rtythm, and contractile vigor after up to 60 minutes of ischemia. In contrast, all hearts not administered tetrodotoxin showed bradycardia, irregular rhythm, and weak contraction upon reperfusion after 30 and 45 minutes of ischemia; after 60 minutes, no mechanical activity was evident. The improved cardiac function following ischemia in the tetrodotoxin-treated hearts was associated with persistence of normal adenosine triphosphate (ATP) levels after up to 30 minutes of ischemia and normal or elevated creatine phosphate (CP) levels after up to 60 minutes of ischemia. On the other hand, ATP and CP levels progressively declined to reach 50 per cent of normal values after 30 minutes in the ischemic hearts without tetrodotoxin. These findings indicate that postarrest ATP and CP levels play an important role in myocardial recovery after ischemic arrest.

The advantages of transthoracic placement of permanent cardiac pacemaker electrodes.

To determine the effect of stimulation site on cardiac pacing thresholds, identical, small-surface area, cathodal, Elgiloy electrodes were placed intramyocardially on the left and right ventricular apices and transvenously into the right ventricular apex of 20 dogs in complete heart block. At seven stimulus durations, threshold voltage and current were measured directly with an oscilloscope and current probe. Left ventricular intramyocardial pacing required less threshold stimulus energy than right ventricular intramyocardial or right ventricular endocardial pacing. Previous studies that determined lower thresholds with transvenous right ventricular endocardial leads than with directly placed myocardial leads used stimulating electrodes of differing configuration, surface area, and materials at the different sites and/or used epicardial rather than intramyocardial electrodes. These factors biased the results in favor of the endocardial site. When all clinical and electrophysiological facotrs are considered, direct intramyocardial placement of electrodes deserves a much wider acceptance and application than it now enjoys.

Effect of perfusate temperature on myocardial protection from ischemia.

During reperfusion, functional and metabolic recovery of the isolated working rat heart from one hour of ischemia was best in hearts selectively cooled at the onset of the ischemic interval by perfusion with 5 to 10 ml. of 10 degrees C. or 15 degrees C. Krebs-Henseleit buffer. Hearts similarly perfused at 4 degrees C., 20 degrees C. recovered significantly less well or not at all. Immediately after the hour of ischemia and prior to reperfusion, the absolute levels of glycogen and high-energy phosphates were best in the hearts perfused at 4 degrees C. However, metabolic function was best preserved in those perfused at 10 degrees C. and 15 degrees C., as evidenced by rapid recovery of high-energy phosphates and glycogen to control levels compared to metabolic deterioration in the 4 degrees C. group.

Reliability audit of a regional cardiac surgery registry.

OBJECTIVE: The British Columbia Provincial Cardiac Registry collects demographic and clinical data on all patients who undergo cardiac surgery procedures in the province. The purpose of this study was to compare the reliability of data contained in Registry with data contained in hospital charts. METHODS: Registry and hospital charts were compared for 480 cases. Thirty cases were randomly selected for the province's 16 cardiac surgeons. For each case, 10 distinct fields were selected for analysis and classified as consistent, inconsistent, or rejected (data unavailable in one or other source). RESULTS: The overall rate of consistency between charts and the Registry was 86.4%, with an inconsistency rate of 9.9% and a rejection rate of 3.7%. Consistency rates varied significantly across the 10 fields and among the 16 surgeons. Pairwise comparisons of rates between fields indicated that specific field types were problematic and should be targeted for improvement. In addition, pairwise comparisons of rates between surgeons indicated that further education on Registry use is required. CONCLUSIONS: Recommendations for database design and management include provision of standard definitions for all fields; education of users; extension of the number of mandatory fields; revision of check-off box fields to yes/no/unsure fields; and collection of data close to the time that it is generated.

The Carpentier-Edwards supraannular porcine bioprosthesis. A new generation tissue valve with excellent intermediate clinical performance.

The Carpentier-Edwards supraannular porcine bioprosthesis, an investigational valve, was implanted in 1167 patients (1174 operations, 1274 valves) between November 1981 and December 1985 (age range 13 to 85 years, mean 61 years). The early mortality rate was 7.2% (with concomitant procedures 10.9%, without 4.8%; with previous operation 10.5%, without 6.6%). The late mortality rate was 4.5% per patient-year (aortic valve replacement, 4.0%; mitral valve replacement, 4.8%; multiple valve replacement, 5.6%). Total cumulative follow-up was 2272.3 years. The prevalence of thromboembolism was 2.6% per patient-year (fatal 0.4% per patient-year, major 1.4%, minor 1.2%); hemorrhage related to antithromboembolic therapy, 0.7% (fatal 0.1%); prosthetic valve endocarditis, 0.4% (fatal 0.2%); periprosthetic leak, 0.4% (fatal 0%); structural valve deterioration (primary tissue failure/structural failure), 0.1% per patient-year; and clinical valve dysfunction, 0.4%. The reoperation rate was 0.8% per patient-year (thromboembolism, 0.1%; clinical valve dysfunction, 0.1%; prosthetic valve endocarditis, 0.1%; periprosthetic leak, 0.4%; structural valve deterioration, 0.1%). Thromboembolism occurred throughout the observation period but with decreasing frequency, hemorrhage throughout the period in no predictable fashion, prosthetic valve endocarditis within 2 years, periprosthetic leak within 2 years, and structural valve deterioration occurred during the fourth year of assessment. The overall survival rate was 79.8% +/- 1.7% (4 years). Freedom (at 4 years) from thromboembolism was 92.2% +/- 1.2%; from structural valve deterioration, 98.8% +/- 0.8%; and from reoperation, 95.8% +/- 1.3%. Freedom from all complications (4 years) was 85.9% +/- 1.7%; from complication mortality, 98.4% +/- 0.4%; and from valve failure (mortality and reoperation), 94.3% +/- 1.3%. This investigational Carpentier-Edwards supraannular porcine bioprosthetic valve has provided excellent clinical performance and remains our overall prosthesis of choice.

Primary cardiac tumors: experience with 25 cases.

The case histories of patients with primary cardiac neoplasms are presented. The mean age was 49.6 years and females predominated (17:8). Nineteen of the tumors were benign (76%), 18 myxomas and one mesenchymal hamartoma. There were six malignant neoplasms; two myxosarcomas, two rhabdomyosarcomas, one skeletal angiomatosis, and one malignant melanoma. The clinical presentation was congestive heart failure in 17 patients and peripheral embolization in five (one patient with both). There were four asymptomatic patients. Antemortem diagnosis was made in 20 patients and five were discovered at autopsy. After 1970, almost 95% of the patients were diagnosed preoperatively while only 14% of the patients had preoperative diagnosis before 1970. Cardiac catheterization and echocardiography were the most useful diagnostic procedures performed but a computed tomographic scan of the heart performed in a patient with right ventricular hamartoma was of great value in delineating the lesion. Twenty-one patients underwent a total of 26 operations but complete excision of the lesion was possible in only 16 patients. Three patients underwent extensive resection and reconstruction. Associated procedures consisted of coronary artery bypass grafts in two patients, mitral valve annuloplasty in one, and a right lung biopsy. Although there was no operative mortality following the original procedure, one patient died after a third operation for recurrence and another underwent unsuccessful emergency pericardiectomy. All patients with malignant lesions died from recurrence 6 to 13 months postoperatively while only three patients in the benign group died and these of unrelated causes. Surgical resection is the treatment of choice for all primary cardiac neoplasms since it is curative in the benign tumors and may prolong life for up to a year with malignant tumors.

The Carpentier-Edwards standard porcine bioprosthesis. A first-generation tissue valve with excellent long-term clinical performance.

The Carpentier-Edwards standard porcine bioprosthesis was implanted in 1190 patients (1201 operations, 1303 valves) between January 1975 and June 1986; most implants were before 1982. The mean age of the patients was 57.2 years (range 8 to 85 years). The early mortality was 7.6% (aortic valve replacement 5.1%, mitral valve replacement 8.8%, and multiple valve replacement 15.3%). Late mortality was 3.9% per patient-year (aortic valve replacement 3.6%, mitral valve replacement 4.2%, and multiple valve replacement 3.8%). The total cumulative follow-up period was 6737 years. Thromboembolism was 1.5% per patient-year (fatal 0.4% per patient-year) (minor 0.6%, major 0.9%); antithromboembolic therapy-related hemorrhage was 0.5% (fatal 0.1%); prosthetic valve endocarditis was 0.6% (fatal 0.2%); nonstructural dysfunction was 0.5% (fatal 0.2%); and structural valve deterioration and/or primary tissue failure was 1.5% per patient-year (fatal, 0.2% per patient-year). Thromboembolism and structural valve deterioration were the significant complications, structural valve deterioration occurring primarily between the sixth and 10th year of evaluation. The overall patient survival was 65.0% for aortic valve replacement and 54.8% for mitral valve replacement (p less than 0.05) at 10 years. The patients were classified as 92.9% New York Heart Association functional classes III and IV preoperatively and 92.3% classes I and II postoperatively. Freedom at 10 years from thromboembolism was 84.3% for aortic valve replacement and 76.5% for mitral valve replacement (p = 0.05); structural valve deterioration was 78.6% for aortic valve replacement and 71.6% for mitral valve replacement (p less than 0.05); reoperation was 74.4% for aortic valve replacement and 67.1% for mitral valve replacement (p less than 0.05). Freedom from all valve-related complications at 10 years was 58.9% for aortic valve replacement and 46.8% for mitral valve replacement (p less than 0.05); valve-related mortality was 89.5% for aortic valve replacement and 82.6% for mitral valve replacement (p = not significant); mortality and reoperation was 58.9% for aortic valve replacement and 46.8% for mitral valve replacement (p less than 0.05); mortality and residual morbidity (treatment failure) was 87.2% for aortic valve replacement and 75.1% for mitral valve replacement (p = not significant); mortality, residual morbidity, and reoperation were 66.3% for aortic valve replacement and 54.9% for mitral valve replacement (p less than 0.05). The standard Carpentier-Edwards porcine bioprosthesis has provided satisfactory clinical performance and has afforded patients excellent quality of life.

Pregnancy and childbearing in a population with biologic valvular prostheses.

Long-term performance of biological prostheses and course of pregnancy, labor, and delivery were evaluated in women less than 35 years of age. Between 1975 and 1987, 87 female patients received a porcine (n = 86) or pericardial valve (n = 1); the mean patient age was 26.8 years, with a range of 8 to 35 years. A total of 17 of these patients experienced 37 pregnancies. A total of 25 babies were delivered, of which 19 were babies of normal birth weight born at term and six were born prematurely (two of these were stillborn). There were six spontaneous abortions and five therapeutic abortions. The mean time from primary operation to first delivery was 29 months. Of the 17 pregnant patients, 14 were in normal sinus rhythm and three were in atrial fibrillation. One of those in fibrillation had a therapeutic abortion while receiving warfarin therapy, and another was successfully delivered of her neonate after 7 months of warfarin therapy. The remaining 15 patients were treated through 35 pregnancies without anticoagulants or antiplatelet agents. Of the total population of 87 patients, 32 (36.8%) were treated for valve-related complications. Structural valve deterioration occurred in eight patients (47.1%) of the pregnancy group and 10 patients (14.3%) of the nonpregnancy group (p less than 0.05). The freedom from structural valve deterioration at 10 years was 23.3% +/- 14% for the pregnancy group and 74.2% +/- 8.5% for the nonpregnancy group (p less than 0.05, age as a determinant, p not significant). There were eight valve-related deaths (1.5%/patient-year). Reoperation was performed in 59% of the pregnancy group and 19% of the nonpregnancy group, primarily for structural valve deterioration manifested as valvular obstruction from aggressive calcification (p less than 0.05). The freedom from reoperation at 10 years parallels freedom from structural valve deterioration (20.3% +/- 12.4% and 64.3 +/- 9.1% for the pregnancy and nonpregnancy groups, respectively, with p less than 0.05; with age added as a determinant, p not significant). The overall reoperative mortality was 8.7% (two patients). The biologic prostheses afforded successful pregnancy without fetal wastage or congenital anomalies and without significant maternal morbidity or mortality.

The changing status of ejection fraction as a predictor of early mortality following surgery for acquired heart disease.

Several reports in the literature and our experience prior to 1974 support the thesis that operative risk in patients with acquired heart disease and poor ventricular function (as assessed by a biplane ejection fraction [EF] less than or equal to 0.40) was very significantly increased over the risk in patients with normal ventricular function. These results led to disagreement in the literature regarding the advisability of surgery in patients with poor ventricular function. Various EFs from less than 0.31 to less than 0.50 were suggested as contradicting elective surgery, while more aggressive groups recommended surgery in all patients with angina. Precise comparison of the results reported by different groups was not always possible because of the common reliance on single-plane right anterior oblique ventriculograms, which tend to underestimate EF and overestimate operative risk. Using biplane ventribulograms for accurate estimation of EF, we have demonstrated a significant reduction in 30-day operative risk to a clinically acceptable 3 percent (1/32) for single valve replacement and aortocoronary surgery patients with poor ventricular function (EF less than or equal to 0.40) during 1974. Considering the high risk of medically treated patients with reduced ventricular function, these results support further evaluation of surgical palliation for patients with valvular or coronary heart disease and reduced ventricular function.

Carpentier-Edwards supra-annular porcine bioprosthesis. Clinical experience and implantation characteristics.

The investigational Carpentier-Edwards supra-annular valve was implanted in 592 patients from November, 1981, to February, 1984 (aortic valve replacement in 286, mitral valve replacement in 259, and multiple valve replacement in 47, for a total of 638 prostheses). A previous cardiac operation had been performed in 77 patients (13%). Concomitant procedures were performed in 202 patients (34.1%), including coronary artery bypass in 163 patients. The patient evaluation was 98.6% complete. The early mortality was 7.4% (44 patients) and the late mortality was 6.2% per patient-year (41 patients). The valve-related causes of late mortality were thromboembolism (five), anticoagulant-related hemorrhage (one), and prosthetic valve endocarditis (one). The overall patient survival, including operative death, was 85% at 2 years. The linearized occurrence rate for valve-related complications was 5.6% per patient-year (37 events)--thromboembolism 2.7% per patient-year (18) anticoagulant-related hemorrhage 1.2% (eight), prosthetic valve endocarditis 0.8% (five), and periprosthetic leak 0.9% per patient-year (six). There were no cases of primary tissue failure or structural failure. At 2 years, the freedom from valve-related complications was 86.9%, from valve-related mortality, 98.7%, and from valve-related mortality and reoperation, 97.7%. This valve is fixed in glutaraldehyde at low pressure and is designed to improve durability. It has provided a low incidence of valve-related complications without structural failure. The structural design of the prosthesis does not always conform to the anatomy of bicuspid aortic valves.

The mechanism of myocardial damage following potassium citrate (Melrose) cardioplegia.

To determine the reasons for clinical failure of Melrose solution, potassium arrest was studied in isolated working rat hearts. Eight control hearts were stable for 2-1/2 hours. After 1/2 hour of work, 42 experimental hearts were subjected to 1 hour of ischemis by aortic cross-clamping with unmodified ischemia in eight hearts and ischemia with simultaneous intracoronary injection of 5 ml. of 4 degrees C. (1)Krebs-Henseleit buffer in seven hearts (2)potassium chloride buffer in six hearts, (3)potassium citrate buffer in eight hearts (both 26 mEq. per liter of K, approximately 300 mOsm. per liter), (4)Melrose solution in seven hearts (greater than 200 mEq. per liter of K, greater than 400 mOsm. per liter), (5)hypertonic potassium citrate buffer in six hearts (26 mEq. per liter of K, greater than 400 mOsm. per liter). The pH of all solutions was 7.8 plus or minus 0.1. After recovery isotonic potassium citrate- and potassium chloride-arrested hearts and time-matched control hearts showed no significant differences in cardiac output, coronary flow, systolic pressure, or heart rate. Hypertonic potassium citrate decreased the recovery of cardiac function after arrest and Melrose arrest was not significantly different from unmodified ischemia. Intracoronary cold isotonic Krebs-Henseleit buffer was better than Melrose arrest but inferior to 26 mEq. er liter of potassium arrest. Arrest with 26 mEq. per liter of potassium augments perfusion hypothermia and prevents significant functional and histologic myocardial damage during 1 hour of ischemis. Previous authors assumed that hypertonicity and citrate were responsible for poor results with Melrose solution, but high potassium concentration is the major deleterious factor with hypertonicity playing a contributory role.