Relationship between regional cardiac hyperinnervation and ventricular arrhythmia.

BACKGROUND: Sympathetic nerve activity is known to be important in ventricular arrhythmogenesis, but there is little information on the relation between the distribution of cardiac sympathetic nerves and the occurrence of spontaneous ventricular arrhythmias in humans. METHODS AND RESULTS: We studied 53 native hearts of transplant recipients, 5 hearts obtained at autopsy of patients who died of noncardiac causes, and 7 ventricular tissues that had been surgically resected from the origin of ventricular tachycardia. The history was reviewed to determine the presence (group 1A) or absence (group 1B) of spontaneous ventricular arrhythmias. Immunocytochemical staining for S100 protein, neurofilament protein, tyrosine hydroxylase, and protein gene product 9.5 was performed to study the distribution and the density of sympathetic nerves. The average left ventricular ejection fraction was 0.22+/-0.07. A total of 30 patients had documented ventricular arrhythmias, including ventricular tachycardia and sudden cardiac death. A regional increase in sympathetic nerves was observed around the diseased myocardium and blood vessels in all 30 hearts. The density of nerve fibers as determined morphometrically was significantly higher in group 1A patients (total nerve number 19.6+/-11.2/mm(2), total nerve length 3.3+/-3.0 mm/mm(2)) than in group 1B patients (total nerve number 13.5+/-6.1/mm(2), total nerve length 2.0+/-1.1 mm/mm(2), P<0. 05 and P<0.01, respectively). CONCLUSIONS: There is an association between a history of spontaneous ventricular arrhythmia and an increased density of sympathetic nerves in patients with severe heart failure. These findings suggest that abnormally increased postinjury sympathetic nerve density may be in part responsible for the occurrence of ventricular arrhythmia and sudden cardiac death in these patients.

Fee-for-benefit: a strategy to improve the quality of health care and control costs through reimbursement incentives.

OBJECTIVES: The purpose of this study was to determine whether reimbursement in direct proportion to expected therapeutic benefit is capable of improving the utilization and cost of health care. BACKGROUND: The benefit associated with a particular medical or surgical treatment varies widely from patient to patient. Nevertheless, payment to the provider of the treatment is essentially invariant under the current fee-for-service system. Under an alternative fee-for-benefit strategy, empiric data are used to construct a multivariate model to predict the expected benefit to an individual patient from a particular health care service on the basis of conventional clinical descriptors. The payers and the providers of the service then openly negotiate an explicit economic relation between expected benefit and monetary payment such that payment is directly proportional to benefit. METHODS: Computer simulations were performed to determine the potential impact of this fee-for-benefit strategy with respect to medical versus surgical treatment of coronary artery disease. RESULTS: Compared with conventional fee-for-service, fee-for-benefit resulted in a 12% improvement in patient benefit (quality-adjusted survival), a 22% reduction in provider payments and a 55% increase in cost/benefit (the ratio of benefit to payment). CONCLUSIONS: The incentives embodied in a fee-for-benefit strategy can be an effective mechanism for encouraging more appropriate health care utilization while simultaneously controlling health care costs.

Incremental prognostic value of exercise thallium-201 myocardial single-photon emission computed tomography late after coronary artery bypass surgery.

OBJECTIVES: This study assessed the incremental prognostic value of exercise thallium-201 myocardial perfusion single-photon emission computed tomography (SPECT) performed > or = 5 years after coronary artery bypass surgery. BACKGROUND: Thallium-201 scintigraphy has shown significant prognostic value in a variety of populations with suspected and known coronary artery disease. However, its value in patients with previous bypass surgery remains unknown. METHODS: We studied 294 patients who were prospectively followed up. Cox proportional hazards models for prediction of "hard" events (cardiac death and nonfatal infarctions) were constructed, with variables considered for inclusion in hierarchic order: clinical and exercise data first, followed by scintigraphic information. RESULTS: Mean (+/- SD) follow-up duration after scintigraphy was 31 +/- 11 months. There were 20 cardiac deaths and 21 nonfatal acute myocardial infarctions. Twenty-nine patients had late (> 60 days after thallium-201 SPECT) revascularization procedures or underwent repeat bypass surgery or percutaneous transluminal angioplasty. Shortness of breath and peak exercise heart rate were the most important clinical predictors of hard events. Two scintigraphic variables added significant prognostic information to the clinical model: the thallium-201 summed reversibility score (summation of segmental differences between stress and redistribution scores) and the presence of increased lung uptake of the radiotracer. The global chi-square statistic for this model was twice as high as that for the clinical/exercise model alone (49.7 vs. 24.2). When a second multivariate Cox model was built adding "soft" events (i.e., late revascularization procedures) as outcomes of interest, the summed reversibility score was selected as an independent scintigraphic predictor of events. The global chi-square statistic for this model was 50.7, three times as high as that for the clinical/exercise model alone. CONCLUSIONS: After evaluation of treadmill and exercise data, thallium-201 myocardial perfusion SPECT provided incremental prognostic information in patients late after bypass.

Clinical and nonclinical predictors of the cost of coronary bypass surgery: potential effects on health care delivery and reimbursement.

BACKGROUND: Health care providers are being pressured to lower the cost of care. Because of the inherent cost variability in providing health care, as reimbursement falls, providers may not be able to cover all costs. Understanding the underlying causes of this wide variability is important in determining optimum pricing. Prior studies on the cost of coronary bypass surgery have determined which clinical variables affect cost, yet none have studied nonclinical variables that can influence the cost of coronary bypass surgery. METHODS: In a cohort of 882 consecutive patients with treatment classified in the diagnosis-related group (DRG) 107, we examined 55 clinical and nonclinical variables obtained from our prospective database. For explanatory purposes, we used multiple linear regression to determine the variables that were predictive of direct cost and the magnitude of contribution of each variable. RESULTS: Eleven clinical and 4 nonclinical variables were predictive of direct cost. Nonclinical variables added significant cost-predictive information beyond that of the traditional clinical variables, and their magnitude of effect was equal to or greater than the traditional clinical variables. CONCLUSIONS: Nonclinical patient characteristics add important predictive information concerning the cost of coronary bypass surgery to traditional clinical variables. These data will be important in developing contracting strategies, in the evaluation of individual physician performance, and in modifying national methods of reimbursement.

Anemia therapy: individual benefit and societal cost.

The US health care system is under increasing pressure to lower costs while maintaining quality of care. Providers will be forced to (1) measure the benefits of a particular therapy, and (2) demonstrate that the benefits justify the costs. The major components of therapeutic benefit are survival and quality of life. Chronic anemia may have little impact on survival, but studies have measured significant decrements in quality of life without therapy and increments in quality of life with therapy. This disease also presents important societal financial concerns due to its many competing therapies. The annual cost of treatment can vary from an average of a few dollars for iron supplementation to an average of $6,000 for a course of recombinant human erythropoietin. Physicians need to integrate information on therapeutic outcomes and cost to maximize individual benefit and justify the costs. The choice of therapy for anemia associated with cancer is complex because the onset of the anemia is multifactorial, and the effects of anemia may be masked by the underlying malignancy. There are insufficient data supporting a specific recommendation for transfusion or recombinant human erythropoietin therapy. The current cost-conscious environment in the United States presents an opportunity for health care providers to formally document the benefits of anemia therapy and justify the societal costs based on those benefits. Anemia is an excellent example of a condition that allows the formal analysis of disease impact and the effectiveness and cost of therapy because (1) it has multiple therapies, (2) the cost of therapy varies widely, and (3) the therapies have variable benefit depending on the individual patient. Using a model based on chronic renal failure, an outcomes structure was developed by which the impact of anemia and the therapies used to manage it can be measured. Its potential application to anemia in patients with cancer is discussed.

Prior restraint: a Bayesian perspective on the optimization of technology utilization for diagnosis of coronary artery disease.

In conclusion, at least 1/3 of patients with suspected coronary artery disease are inappropriately referred for scintigraphic diagnostic testing from a Bayesian such as those described in this report, may be a powerful mechanism for encouraging more appropriate technology utilization while simultaneously controlling costs, and are thereby deserving of a formal prospective demonstration trial. However, since only half the patients currently being tested are referred for diagnostic purposes, analogous strategies must be developed with respect to prognostic and therapeutic evaluation.

Rate-dependent effects of procainamide on His-Purkinje conduction in man.

Microelectrode studies in isolated cardiac tissues have shown that the depressant effect of several antiarrhythmic drugs on the maximal upstroke velocity of the cardiac action potential is rate-dependent. To determine whether this effect of antiarrhythmic drugs is seen in humans, 14 patients undergoing atrial pacing at several rates were prospectively studied before and after the infusion of procainamide (15 mg/kg). The HV interval (His-Purkinje conduction rate) and the QRS duration (intraventricular conduction rate) were measured. Before procainamide infusion, atrial pacing did not significantly prolong the maximal HV interval (from 54 +/- 15 to 58 +/- 13 ms). After procainamide infusion (mean serum level 10.0 +/- 3 micrograms/ml) atrial pacing at an average of 5 pacing rates significantly prolonged the HV interval (from 67 +/- 18 to 80 +/- 20 ms, p less than 0.001). The extent of HV prolongation with atrial pacing after procainamide infusion was independent of the HV interval at rest before procainamide. The duration of the QRS complex also tended to prolong with atrial pacing after procainamide infusion, but this prolongation was not statistically significant. Thus, procainamide produces a rate-dependent depressant effect on His-Purkinje and intraventricular conduction, confirming observations made in isolated tissue preparations.

Twenty-year follow-up of patients with new perioperative Q waves after coronary artery bypass grafting.

It is unclear whether the development of new Q waves on the electrocardiogram after coronary artery bypass grafting (CABG) is associated with an adverse prognosis. We analyzed the 20-year survival of 227 patients who underwent CABG, and found that new perioperative Q waves had no impact on long-term survival; therefore, conservative management may be appropriate for uncomplicated patients with new Q waves after CABG.

Radial artery harvesting for coronary bypass operations: neurologic complications and their potential mechanisms.

OBJECTIVES: We sought to determine the incidence of self-reported neurologic hand complications after radial artery harvest for coronary artery bypass grafting. METHODS: Between February 20, 1996, and December 31, 1999, 615 patients underwent coronary bypass operations with radial arteries. A scripted telephone interview was performed, collecting data on perceived thumb weakness and sensation abnormalities in the distribution of the radial nerve in 560 patients. The average time to follow-up interview was 14.5 +/- 9 months. RESULTS: Neurologic complications were reported in 30.1%, decreased thumb strength in 5.5%, and any sensation abnormality in 18.1% of patients. There was a high rate of symptom improvement over an average of 8.7 +/- 7.5 months, such that only 12.1% of patients reported symptoms without any improvement. Associations between thumb weakness and sensory abnormalities imply median nerve damage in some patients. There were statistically significant associations between neurologic complications and diabetes, peripheral vascular disease, elevated creatinine levels, smoking, and number and site of radial artery harvest. CONCLUSIONS: The overall rate of self-reported neurologic complications after radial artery harvest was higher than previously reported. These symptoms may be attributable to radial and median nerve injury caused by trauma and devascularization. These data have important implications not only in attempting to improve harvesting techniques but also in guiding informed consent before coronary artery bypass grafting.

Hospital-based group: ideal practice for the future?

The format for future cardiothoracic surgical practices includes the option of a hospital-based group where provider groups and the hospital share the responsibilities and obligations of clinical care and the cost of that care. Based on personal experience at the Cedars-Sinai Medical Center, Los Angeles, three separate contract relationships during our tenure have reflected the evolution of cardiothoracic surgeons' relationship to our patients and the hospital in which we work. Although other organizational modes may prove equally successful, the hospital-based group practice is a viable structure that supports the preservation of quality in the work performed. This relationship helps to maintain a steady volume of patients enabling research endeavors, which are primarily funded through practice incomes, to continue and it also provides a platform for networking with defined patient referrals, shared services, and bench-marking with other centers.

Optimizing cardiothoracic surgery information for a managed care environment.

The rapid change occurring in American healthcare is a direct response to rising costs. Managed care is the fastest growing model that attempts to control escalating costs through limitations in patient choice, the active use of guidelines, and placing providers at risk. Managed care is an information intensive system, and those providers who use information effectively will be at an advantage in the competitive healthcare marketplace. There are five classes of information that providers must collect to be competitive in a managed care environment: patient satisfaction, medical outcomes, continuous quality improvement, quality of the decision, and financial data. Each of these should be actively used in marketing, assuring the quality of patient care, and maintaining financial stability. Although changes in our healthcare system are occurring rapidly, we need to respond to the marketplace to maintain our viability, but as physicians, we have the singular obligation to maintain the supremacy of the individual patient and the physician-patient relationship.

A cardiothoracic surgery information system for the next century: implications for managed care.

The United States health care system is under tremendous pressure to cut costs while maintaining quality. One mechanism to reduce costs is managed care--a system with both risks and benefits for patients, providers, and payors, and one that requires large volumes of data to ensure optimal medical and financial decision-making. In this review, we describe the types of information needed by managed care systems, including medical outcome data (satisfaction, survival, quality of life, and complications) and financial data (costs and long-term resource utilization). From a provider's point of view, the customers for these data range from individual patients to large self-insured corporations, and we describe the data required for each potential customer. Finally, as a concrete example of how data can be collected and analyzed to improve a provider's competitiveness, we describe the Cedars-Sinai Medical Center cardiothoracic surgery database from a managed care perspective. The concepts presented are generalizable to other subspecialties, and will become more important in the increasingly competitive milieu of American health care.

Cardiac operations in patients 90 years of age and older.

BACKGROUND: Growth of the elderly population worldwide, and specifically in the United States, will continue to accelerate and will have a profound impact on the cost and delivery of health care resources in the future. A medical strategy that allows the elderly to live independently is essential to most cost-effective use of our resources. The question remains as to what will be the future of surgical therapy for this increasing population. METHODS: We retrospectively studied the cases of 30 consecutive nonagenarians (mean age, 92.3 +/- 1.8 years) who underwent a cardiac operation within a 9-year period. All patients were in New York Heart Association class III or IV and underwent operation urgently or emergently. RESULTS: The 30-day mortality rate was 10%, and the actuarial survival rates were 81% +/- 8% and 75% +/- 9% at 1 year and 2 years, respectively. Seventy-eight percent of survivors were in New York Heart Association class I or II within 2 years after operation and had an improved quality of life. The cost of providing care in this age group was 24% higher than in octogenarians. CONCLUSIONS: Advanced age in and of itself (>90 years) should not be a contraindication to an open-heart operation, although morbidity, mortality, and cost may be higher. However, selective criteria identifying risks and benefits for individual patients should be applied. The aging of our population will have a profound impact on the cost and delivery of health care resources in the future. This issue must be addressed in the current debate on the provision of expensive procedures under a realigned national health-care system.

Heart transplantation in patients 70 years of age and older: initial experience.

BACKGROUND: Heart transplantation has become a highly successful therapeutic option for patients with end-stage cardiomyopathy. Consequently, the criteria for patient selection, particularly regarding recipients' upper age limits, have been expanded, with an increasing number of people older than 60 years of age now undergoing transplantation. METHODS: A retrospective analysis of 6 patients 70 years of age and older who underwent heart transplantation was done; their clinical courses and outcomes were compared with those of younger patients, with a special emphasis on their posttransplantation quality of life. RESULTS: All 6 patients are alive and clinically well at a mean follow-up of 12 months. No age-related complications have been observed, and their quality of life is excellent. There has been a very low incidence of rejection, as well as few episodes of rejection. CONCLUSIONS: Heart transplantation in selected people 70 years of age and older can be performed successfully with a morbidity comparable to that seen in younger patients and excellent short-term survival. This initial experience is encouraging, but further studies and long-term follow-up are needed to validate the more routine application of this therapy.

Cardiac reoperations in octogenarians: analysis of outcomes.

BACKGROUND: With the rapid growth of the elderly segment of the population, more octogenarians are referred for complex cardiac interventions, including reoperations. Data regarding the outcomes, quality of life, and long-term results after reoperative open-heart surgical procedures in octogenarians are scarce. METHODS: We retrospectively studied 113 consecutive octogenarians (mean age, 83+/-2.6 years) who underwent reoperative cardiac procedures within a 13-year period. Coronary artery bypass grafting (CABG) was performed in 49 patients (CABG group), valvular procedures (aortic, mitral, or tricuspid valve, alone or in combination) in 35 (valve group), and combined CABG and valve intervention in 29 (combined CABG and valve group). RESULTS: The 30-day mortality rate was 8% (4 of 49) for the CABG group, 9% (3 of 35) for the valve group, and 17% (5 of 29) for the combined CABG and valve group. One- and 5-year actuarial survival rates were, respectively, 85%+/-5% and 58%+/-10% for the CABG group, 78%+/-7% and 53%+/-12% for the valve group, and 69%+/-9% and 63%+/-10% for the combined CABG and valve group. Sixty-one percent of patients in the CABG group, 40% in the valve group, and 38% in the combined CABG and valve group were in New York Heart Association class I or II postoperatively at a mean follow-up time of 2.1+/-2.4 years. Similarly, 91%, 85%, and 80%, respectively, thought that they had an improved quality of life and were satisfied with their functional status. CONCLUSIONS: Cardiac reoperations can be performed successfully in most octogenarians, although with an increased risk, particularly in the combined CABG and valve group. Long-term survival is acceptable with improved quality of life and functional status. However, it is possible that these results could be improved in this high-risk group of patients with earlier referral and surgical intervention, for the effective use of health care resources.

Intensity of antianginal therapy in patients referred for coronary angiography: a comparison of fee-for-service and health maintenance organization therapeutic strategies.

BACKGROUND: No formal criteria have been developed to guide medical therapy for angina prior to revascularization, and no comparisons have been made between health maintenance organization (HMO) and fee-for-service (FFS) hospitals with respect to angina treatment. HYPOTHESIS: Using a literature-based measure of medical intensity, we tested the hypothesis that there is no difference in anginal medical therapeutic intensity between HMO and FFS systems. METHODS: For each antianginal drug, we developed a model from which an intensity score between 0 and 100 could be calculated. Average and maximal daily doses of drug were fit to a sigmoid curve such that they represented scores of 50 and 99, respectively. Overall intensity scores were obtained by weighted and unweighted averaging of three scores from nitrates, calcium-channel blockers, and beta blockers. This model was applied to 199 patients undergoing angiography at an FFS and an HMO hospital. RESULTS: HMO patients were taking more classes of antianginal drug (1.9 vs. 1.0, p < 0.001). Overall unweighted (17.7 vs. 11.7, p = 0.02) and weighted (27.3 vs. 16.9, p = 0.003) intensity scores for both HMO and FFS patients were low. HMO intensity scores for the use of beta blockers were greater than FFS scores (19.2 vs. 9.6, p = 0.002). The intensity scores for the use of nitrates and calcium blockers were similar. CONCLUSIONS: Models for the measurement of anginal medical therapy intensity can provide important information regarding medical therapy prior to revascularization. The overall intensity of medical therapy was low in both health care systems. These findings have important implications for patient management, guideline development, and national healthcare policy.

Can the analytic techniques of nonlinear dynamics distinguish periodic, random and chaotic signals?

Recent advances in the mathematical discipline of nonlinear dynamics have led to its use in the analysis of many biologic processes. But the ability of the tools of nonlinear dynamic analysis to identify chaotic behavior has not been determined. We analyzed a series of signals--periodic, chaotic and random--with five tools of nonlinear dynamics. Periodic signals were sine, square, triangular, sawtooth, modulated sine waves and quasiperiodic, generated at multiple amplitudes and frequencies. Chaotic signals were generated by solving sets of nonlinear equations including the logistic map, Duffing's equation, Lorenz equations and the Silnikov attractor. Random signals were both discontinuous and continuous. Gaussian noise was added to some signals at magnitudes of 1, 2, 5, 10 and 20% of the signal's amplitude. Each signal was then subjected to tools of nonlinear dynamics (phase plane plot, return map, Poincaré section, correlation dimension and spectral analysis) to determine the relative ability of each to characterize the underlying system as periodic, chaotic or random. In the absence of noise, phase plane plots and return maps were the most sensitive detectors of chaotic and periodic processes. Spectral analysis could determine if a process was periodic or quasiperiodic, but could not distinguish between chaotic and random signals. Correlation dimension was useful to determine the overall complexity of a signal, but could not be used in isolation to identify a chaotic process. Noise at any level effaced the structure of the phase plane plot. Return maps were relatively immune to noise at levels of up to 5%. Spectral analysis and correlation dimension were insensitive to noise. Accordingly, we recommend that unknown signals be subjected to all of the techniques to increase the accuracy of identification of the underlying process. Based on these data, we conclude that no single test is sufficiently sensitive or specific to categorize an unknown signal as chaotic.