Current status of prevention, diagnosis, and management of coronary artery disease in patients with kidney failure.

BACKGROUND: Patients with kidney failure have a heavy burden of coronary artery disease. The results of preventive, diagnostic, and therapeutic measures developed in nonuremic populations cannot automatically be extrapolated to this unique group of patients. METHODS AND RESULTS: Articles were reviewed if they contained English language text or an abstract identified by MEDLINE search from 1980 to 1999, supplemented by manual review of bibliographies of published articles and abstract issues of national cardiology meetings, studies on diagnostic techniques, risk modification measures, pharmacologic agents, and coronary revascularization procedures in patients with uremia. Descriptive and quantitative data as appropriate were extracted. Lipid-lowering agents may be safely administered to uremic patients. Direct evidence of lipid lowering in this population is not available and is not likely to be forthcoming. Erythropoietin therapy is effective in reversing the cardiovascular perturbations of uremic anemia, but an approach of normalizing the hematocrit cannot be recommended. Glycoprotein IIb/IIIa inhibitors used in acute coronary syndromes require downward dose adjustment or are contraindicated. Thrombolytic agents are underutilized in the management of myocardial infarction. Noninvasive testing is less accurate than in nonuremic populations. Coronary revascularization offers relative clinical advantages over medical therapy similar to non-kidney failure populations, even though the results in uremic patients is significantly less favorable than for nonuremic patients. Stenting is the preferred revascularization approach, and conventional balloon percutaneous transluminal coronary angioplasty the least favorable. CONCLUSIONS: Many but not all of the benefits of therapies developed in nonuremic patients extend to patients with kidney failure. Physicians should be familiar with the advantages and limitations of each of these modalities in this population.

Cause of in-hospital death in 12,232 consecutive patients undergoing percutaneous transluminal coronary angioplasty. The Northern New England Cardiovascular Disease Study Group.

BACKGROUND: Some deaths after percutaneous coronary angioplasty (PTCA) occur in high-risk situations (eg, shock), whereas others are unexpected and related to procedural complications. To better describe the epidemiologic causes of death after PTCA, we undertook a systematic review of all in-hospital PTCA deaths in Northern New England from 1990 to 1993. METHODS: The medical records of 121 patients who died during their acute hospitalization for PTCA were reviewed with a standardized data extraction tool to determine a mode of death (eg, low output failure, arrhythmia, respiratory failure) and a circumstance of death (eg, death attributable to a procedural complication, preexisting acute cardiac disease). Any death not classified as a procedural complication was reviewed by a committee and the circumstance of death assigned by a majority rule. RESULTS: Low-output failure was the most common mode of death occurring in 80 (66.1%) of 121 patients. Other modes of death included ventricular arrhythmias (10.7%), stroke (4.1%), preexisting renal failure (4.1%), bleeding (2.5%), ventricular rupture (2.5%), respiratory failure (2.5%), pulmonary embolism (1.7%), and infection (1.7%). The circumstance of death was a procedural complication in 65 patients (53.7%) and a preexisting acute cardiac condition in 41 patients (33.9%). Women were more likely to die of a procedural complication than were men. CONCLUSION: Procedural complications account for half of all post-PTCA deaths and are a particular problem for women. Other deaths are more directly related to patient acuity or noncardiac, comorbid conditions. Understanding why women face an increased risk of procedural complications may lead to improved outcomes for all patients.

Percutaneous transluminal coronary angioplasty in the elderly: epidemiology, clinical risk factors, and in-hospital outcomes. The Northern New England Cardiovascular Disease Study Group.

OBJECTIVES: To explore the relation between older age and clinical presentation, procedural success, and in-hospital outcomes among a large unselected population undergoing percutaneous transluminal coronary angioplasty (PTCA). BACKGROUND: Although more elderly patients are receiving PTCA, studies of post-PTCA outcomes among the elderly have been limited by small numbers and exclusive selection criteria. METHODS: Data were collected as a part of a prospective registry of all percutaneous coronary interventions performed in Maine, New Hampshire, and from 1 institution in Massachusetts between October 1989 and December 1993. Comparisons across 4 age groups, (<60, 60 to 69, 70 to 79, and 80 years and above) were performed using chi-square tests, the Mantel-Haenzsel test for trend, and logistic regression. RESULTS: Twelve thousand one hundred seventy-two hospitalizations for PTCA were performed with 507 of them (4%) in persons at least 80 years old. Octogenarians were more likely to be women, have multivessel disease, high-grade stenoses, and complex lesions but were less likely to have hypercholesterolemia, a history of smoking, or have undergone a previous PTCA. In the elderly, PTCAs were more often performed urgently and for unstable syndromes compared with younger age groups. Advancing age is strongly associated with in-hospital death, and among the oldest old with an increased risk of postprocedural myocardial infarction. Despite differing presentation and procedural priority, angiographic success and subsequent bypass surgery did not vary by age. CONCLUSIONS: With the increasing age of the population at large as well as that segment at risk for cardiac revascularization, information about age-associated risks of the procedure, especially the substantially higher risk of death in octogenarians, will be critical for both physicians and patients considering PTCA.

Economic impact on physicians and hospitals of proposed changes in Medicare reimbursement for coronary interventions.

BACKGROUND: The federal government is implementing changes in reimbursement for angioplasty and coronary stenting. These include reductions in physician reimbursement and a redesignation of intracoronary stents to a different diagnosis-related group than other methods of intracoronary intervention. OBJECTIVE: The aim of this study was to examine the financial impact on physicians and hospitals of proposed federal reimbursement policies for percutaneous coronary revascularization procedures. METHODS: We modeled the financial effects of 3 different stenting strategies: strategy I is the most conservative, with stents reserved for addressing lab complications; strategy II stents are used for suboptimal results after attempts at conventional percutaneous transluminal coronary angioplasty (PTCA); strategy III is the most aggressive, with initial stenting of all accessible lesions. We used economic data on PTCA and stent costs from a 1996 dataset and made assumptions about PTCA and stent success rates and restenosis rates based on published data. RESULTS: Under current reimbursement policies, physician revenues and profits are approximately equal under all 3 stenting strategies. After the proposed changes, there is a slight financial incentive for physicians to pursue the more aggressive strategy III, but the major financial effect is a substantial overall decline in revenues with any of the 3 strategies. For hospitals, the present situation strongly favors the more conservative strategies, but after the proposed changes the more aggressive stenting strategies will be more profitable, thus realigning physician and hospital incentives. Health care delivery organizations that combine physician and hospital income streams achieve the greatest financial stability. CONCLUSIONS: Current reimbursement policies for angioplasty and stenting have created misaligned incentives between physicians and hospitals. Proposed changes do not present physicians with large economic incentives to pursue aggressive versus conservative stent strategies but substantially address the current disparity in hospital financial incentives.

Determinants of rebound thrombin activity after cessation of heparin in patients undergoing coronary interventions.

This study was designed to characterize hemostatic activation (using fibrinopeptide A (FPA), a marker of thrombin activity, and beta-thromboglobulin (BTG), a marker of platelet activation) sequentially in the coronary and peripheral circulation in patients during percutaneous coronary intervention (PCI) and several hours after PCI and discontinuation of heparin therapy. Heparin administered during PCI is known to nonuniformly suppress thrombin activity in the coronary. Persistent elevations of FPA in coronary sinus (CS) blood during PCI have been associated with subsequent ischemic events. As a related consideration, rebound thrombin activity has been demonstrated in peripheral blood samples several hours after cessation of heparin therapy in patients with acute coronary syndromes. Accordingly, we hypothesized that increased thrombin activity occurs in the coronary circulation after PCI and is induced by cessation of intravenous heparin to facilitate vascular sheath removal. Such a rebound prothrombotic effect, may contribute to suboptimal outcomes after PCI. In 21 patients undergoing PCI, heparin-bonded catheters were employed to obtain sequential CS and femoral vein (FV) blood samples for measurement in the coronary and peripheral circulation of plasma FPA, a marker of thrombin activity in vivo, and BTG released by platelets during degranulation. Following heparin administration samples were obtained immediately prior to (base) and during (start and end) PCI. Late samples were obtained several hours after PCI (284 +/- 46 min, mean +/- SD) following the cessation of heparin and prior to planned vascular sheath removal. Mean FPA concentration in CS blood was low at baseline (3.82 +/- 2.09 ng/ml) and did not increase during PCI. Mean FPA concentration in CS blood increased significantly several hours after cessation of heparin (3.42 +/- 2.36 vs. 7.82 +/- 9.98, end vs. late, P < 0.001). In contrast, mean FPA concentration in FV blood was highest at baseline following vascular sheath insertion, decreased during PCI (69%, P < 0.05, base vs. end), and trended upward after PCI and cessation of heparin. Mean FPA values were higher at all times in FV compared with CS blood samples and were not concordant after PCI. Elevation of coronary circulation FPA after PCI was maximal in patients with myocardial infarction within 7 days (13.7 +/- 12.4 vs. 5.6 +/- 7.9 ng/ml, P = 0.08), but was not influenced by heparin treatment prior to PCI, a history of unstable angina, or coronary stent placement during PCI (9 of 21 patients). BTG values showed less variation than did FPA values, and cessation of heparin after PCI was not associated with an increase in BTG in CS or FV blood samples. An increase in thrombin activity occurs in the coronary circulation after PCI following discontinuation of heparin. The extent of increased thrombin activity was greatest in patients with recent myocardial infarction and was not exacerbated by coronary stent placement during PCI. This phenomenon may contribute to the important minority of ischemic complications early after PCI.

The impact of reimbursement changes for intracoronary stents on providers and Medicare.

CONTEXT: New Medicare reimbursement policies will move stents into a different diagnosis-related group (DRG) than conventional balloon angioplasty (percutaneous transluminal coronary angioplasty [PTCA]). OBJECTIVE: To examine the financial impact on hospitals and Medicare of these planned changes, taking into account costs, reimbursement, and the cost-offset effect of prevented complications. DESIGN: The economic impact of proposed reimbursement changes was modeled by using a retrospective clinical and economic data set from a single institution. PATIENTS AND METHODS: A total of 421 consecutive interventional cases from 1996 were examined by using actual cost data. The new, proposed revenues were assigned to these cases. From the hospitals' perspective, the focus was on contribution margin (the difference between revenues and costs), risk adjusted for case-mix severity. From Medicare's perspective, the focus was on expenditures. Various assumptions were adopted for two clinical variables: the effectiveness of stents in preventing the major PTCA-related complications of myocardial infarction and coronary artery bypass graft surgery and the relative proportions of myocardial infarction and coronary artery bypass graft surgery in the mix of complications. Under current Medicare DRG policies, coronary artery bypass graft surgery is highly profitable for hospitals, whereas myocardial infarction as a complication of PTCA has a negative financial impact. RESULTS: Under the new Medicare reimbursement policies, hospitals experience higher profitability with stents than with conventional PTCA under most assumed levels of clinical effectiveness and mixes of myocardial infarction and coronary artery bypass graft surgery. For Medicare, under most circumstances (including percentages of stent use and levels of clinical effectiveness that represent contemporary practice) stents lead to greater expenditures. CONCLUSIONS: Medicare reimbursement changes will substantially realign previously misaligned financial and clinical incentives for hospitals. The immediate effect on hospitals will be to enhance profitability, whereas the effect on Medicare will be to increase expenditures.

The evolving costs of intracoronary stents.

BACKGROUND: As stenting practice has evolved to include greater numbers of stents and adjunctive balloon catheters per case, concern has focused on the increasing costs of equipment for the delivery of stents. METHODS AND RESULTS: To evaluate temporal changes in costs of intracoronary stenting, we examined total costs, catheterization laboratory equipment costs, equipment utilization, and nonlaboratory hospital costs for stent cases for two time periods: Period I (n = 46; 3 months in 1995 involving routine warfarin anticoagulation) and Period II (n = 129; 4 months during which warfarin was being abandoned). Overall costs declined from Period I ($11,293+/-$7672) to Period II ($9819+/-$3636) (p = 0.074). Catheterization laboratory equipment expenditures rose (Period I, $3823+/-$1394 vs Period II, $4278+/-$1533), whereas noncatheterization laboratory hospital costs declined significantly (Period I, $7281+/-$7179 vs Period II, $5560+/-$3420). The difference in costs was most notable when taking into account the deletion of warfarin anticoagulation. Costs declined by $2428 for patients in Period II in whom warfarin was not prescribed (p < 0.05 vs patients in Period I). CONCLUSIONS: We conclude that despite the increasing costs for equipment of stent cases, our overall costs of providing stents declined as warfarin anticoagulation was abandoned.

Cost advantages of an ad hoc angioplasty strategy.

OBJECTIVES: We sought to determine the cost advantage of a strategy of same-sitting diagnostic catheterization and percutaneous transluminal coronary angioplasty (PTCA) (ad hoc) in comparison with staged PTCA. BACKGROUND: It is widely assumed that an ad hoc strategy lowers costs by reducing the length of hospital stay (LOS). However, this assumption has not been examined in a contemporary data set. METHODS: We studied 395 patients undergoing PTCA during 6 consecutive months. Cost analysis was performed using standard cost-accounting methods and a mature cost-accounting system. Costs were examined within three clinical strata based on the indication for PTCA (stable angina, unstable angina and after myocardial infarction [MI]). RESULTS: For the entire patient cohort, there was no significant cost advantage of an ad hoc approach within any of the strata, although there was a nonsignificant trend toward an ad hoc approach in patients with stable angina. For patients treated with conventional balloon PTCA alone, the lack of a significant difference between ad hoc and staged strategies persisted. For patients who received stents, there was a significant cost advantage of an ad hoc approach in all three clinical strata. An important cost driver was the occurrence of complications. Differences in the rates of complications did not reach statistical significance between ad hoc and staged strategies, but even a small trend toward greater complications in patients who had the ad hoc strategy negated cost and LOS advantages. Our study had the power to detect significant cost differences of $1,300 for patients with stable angina, $2,100 for patients with unstable angina and $2,500 for post-MI patients. It is possible that we failed to detect smaller cost advantages as significant. CONCLUSIONS: A cost savings with an ad hoc strategy of PTCA could not be consistently demonstrated. The cost advantage of an ad hoc approach may be most readily realized in clinical settings where the intrinsic risks are low (e.g., stable angina) or in which the device used carries a reduced risk of complications (e.g., stenting), because even a small increase in the complication rate will negate any financial advantage of an ad hoc approach.

Perspectives of electrogastrography and motion sickness.

Electrogastrography (EGG) is a noninvasive measurement of stomach activity using surface electrodes positioned over the abdominal surface. For over 10 years, EGG has been used as an objective measure of epigastric symptoms and nausea experienced in visually induced sickness provoked by circularvection. It was reported that during sickness, there is a shift in the dominant basal electrical activity. The 3 cycles per minute activity decrease and the 4-9 cycles per minute activity increase. This technique has also been used to evaluate the efficacy of antimotion sickness drugs and to monitor sickness induced by other provocative stimuli such as Coriolis cross-coupling, parabolic flight manoeuvres and microgravity. It has been further postulated that peripheral changes in gastric myoelectrical activity in response to visually induced sickness are detected centrally and lead to the generation of motion sickness. However, other studies using either identical or equally effective motion stimuli failed to support the positive correlation of changes in gastric activity with the incidence and severity of motion sickness. The interpretation of spectral analysis on EGG during motion sickness must be taken with great caution. The inherent variability of the EGG and intersubject variability makes it difficult to consider EGG a reliable and robust indicator of motion sickness. Its relation to motion sickness and the underlying mechanism remains unclear. The true diagnostic value of EGG in motion sickness has yet to be determined.

A new time-domain narrowband velocity estimation technique for Doppler ultrasound flow imaging. I. Theory.

A significant improvement in blood velocity estimation accuracy can be achieved by simultaneously processing both temporal and spatial information obtained from a sample volume. Use of the spatial information becomes especially important when the temporal resolution is limited. By using a two-dimensional sequence of spatially sampled Doppler signal "snapshots" an improved estimate of the Doppler correlation matrix can be formed. Processing Doppler data in this fashion addresses the range-velocity spread nature of the distributed red blood cell target, leading to a significant reduction in spectral speckle. Principal component spectral analysis of the "snapshot" correlation matrix is shown to lead to a new and robust Doppler mode frequency estimator. By processing only the dominant subspace of the Doppler correlation matrix, the Cramer-Rao bounds on the estimation error of target velocity is significantly reduced in comparison to traditional narrowband blood velocity estimation methods and achieves almost the same local accuracy as a wideband estimator. A time-domain solution is given for the velocity estimate using the root-MUSIC algorithm, which makes the new estimator attractive for real-time implementation.

A new time-domain narrowband velocity estimation technique for Doppler ultrasound flow imaging. II. Comparative performance assessment.

For pt.I see ibid., vol.45, no.4, pp.939-54 (1998). The statistical performance of the new 2-D narrowband time-domain root-MUSIC blood velocity estimator described previously is evaluated using both simulated and flow phantom wideband (50% fractional bandwidth) ultrasonic data. Comparisons are made with the standard 1-D Kasai estimator and two other wideband strategies: the time domain correlator and the wideband point maximum likelihood estimator. A special case of the root-MUSIC, the "spatial" Kasai, is also considered. Simulation and flow phantom results indicate that the root-MUSIC blood velocity estimator displays a superior ability to reconstruct spatial blood velocity information under a wide range of operating conditions. The root-MUSIC mode velocity estimator can be extended to effectively remove the clutter component from the sample volume data. A bimodal velocity estimator is formed by processing the signal subspace spanned by the eigenvectors corresponding to the two largest eigenvalues of the Doppler correlation matrix. To test this scheme, in vivo common carotid flow complex Doppler data was obtained from a commercially available color flow imaging system. Velocity estimates were made using a reduced form of this data corresponding to higher frame rates. The extended root-MUSIC approach was found to produce superior results when compared to both 1- and 2-D Kasai-type estimators that used initialized clutter filters. The results obtained using simulated, flow phantom, and in vivo data suggest that increased sensitivity as well as effective clutter suppression can be achieved using the root-MUSIC technique, and this may be particularly important for wideband high frame rate imaging applications.

Economic impact of angioplasty salvage techniques, with an emphasis on coronary stents: a method incorporating costs, revenues, clinical effectiveness and payer mix.

OBJECTIVES: We sought to broaden assessment of the economic impact of percutaneous transluminal coronary angioplasty (PTCA) revascularization salvage strategies by taking into account costs, revenues, the off-setting effects of prevented clinical complications and the effects of payer mix. BACKGROUND: Previous economic analyses of PTCA have focused on the direct costs of treatment but have not accounted either for associated revenues or for the ability of costly salvage techniques such as coronary stenting to reduce even costlier complications. METHODS: Procedural costs, revenues and contribution margins (i.e., "profit") were measured for 765 consecutive PTCA cases to assess the economic impact of salvage techniques (prolonged heparin administration, thrombolysis, intracoronary stenting or use of perfusion balloon catheters) and clinical complications (myocardial infarction, coronary artery bypass graft surgery [CABG] or acute vessel closure with repeat PTCA). To assess the economic impact of various salvage techniques for failed PTCA, we used actual 1995 financial data as well as models of various mixes of fee-for-service, diagnosis-related group (DRG) and capitated payers. RESULTS: Under fee-for-service arrangements, most salvage techniques were profitable for the hospital. Stents were profitable at almost any level of clinical effectiveness. Under DRG-based systems, most salvage techniques such as stenting produced a financial loss to the hospital because one complication (CABG) remained profitable. Under capitated arrangements, stenting and other salvage modalities were profitable only if they were clinically effective in preventing complications in > 50% of cases in which they were used. CONCLUSIONS: The economic impact of PTCA salvage techniques depends on their clinical effectiveness, costs and revenues. In reimbursement systems dominated by DRG payers, salvage techniques are not rewarded, whereas complications are. Under capitated systems, the level of clinical effectiveness needed to achieve cost savings is probably not achievable in current practice. Further studies are needed to define equitable reimbursement schedules that will promote clinically effective practice.

Cardiologists' perception of risk of coronary revascularization procedures.

We sought to determine if differences exist between interventional and noninterventional cardiologists in the perception of risk of revascularization procedures and to compare the physicians' estimates with a computer-based predictor formula from a large regional database. We found that interventional cardiologists perceived greater risk of percutaneous transluminal coronary angioplasty-related morbidity and mortality than noninterventionalists and that these differences were accentuated in female patients, the elderly, and the most seriously ill patients.

Patient acceptance of reused angioplasty equipment.

The reuse of percutaneous transluminal coronary angioplasty (PTCA) balloon catheters has recently been proposed as a way of containing costs. Our aim was to examine patient acceptability of this strategy. We asked 100 consecutive patients scheduled for potential or definite PTCA whether they would permit the use of sterilized, reused balloon catheters. We collected demographic, clinical, angiographic, and insurance-status data on all patients. Sixty-eight patients responded that they would have allowed reused equipment (group 1). Thirty-two patients would have refused (group 2). Only three group 2 patients could be enticed to change their opinions by appealing to their altruism or self-interest. The two groups of patients could not be distinguished by any variable, including insurance status. We conclude that a sufficient number of patients would be willing to permit reused PTCA equipment for such programs to be implemented successfully from a logistic standpoint. However, the disapproval by one third of patients raises the possibility of adverse publicity and litigation for institutions using such strategies.

Results of directional coronary atherectomy in Northern New England. Northern New England Cardiovascular Disease Study Group.

The role of directional coronary atherectomy (DCA) in interventional cardiology remains uncertain. We report the Northern New England regional experience with DCA from 1991 to 1994. Data were collected on 11,178 patients having had an intervention on a single lesion in a single vessel (798 DCAs; 10,380 percutaneous transluminal angioplasties [PTCA]). The use of DCA increased from 1.8% of interventions in 1991 to 10% in 1994. Compared with PTCA, DCA patients were younger, more often men, had more 1-vessel disease and more coronary artery bypass surgery (CABG). DCA was more often used in the left anterior descending artery, in vein grafts, for restenoses, for subtotal occlusions, and with type A lesions. Angiographic success (96.7%) and clinical success (93%) were good. Adverse events were rare: mortality 0.9%, emergent CABG 2.2%, nonfatal myocardial infarction 2.8%. After adjusting for case-mix, there was no difference between DCA and PTCA for in-hospital mortality (odds ratio [OR] = 1.03, 95% confidence interval [CI] 0.44 to 2.43, p = 0.95) or need for emergent CABG (OR = 1.27, 95% CI 0.77 to 2.10, p = 0.34). Atherectomy patients were more likely to have a nonfatal myocardial infarction (OR = 2.0, 95% CI 1.26 to 3.20, p <0.01), to sustain an injury to the femoral or brachial artery (OR = 2.89, 95% CI 1.52 to 5.51, p <0.01), and to have a clinically successful procedure (OR = 1.37, 95% CI 1.01 to 1.88, p = 0.05). Our results support the relative safety and effectiveness of DCA as its use disseminated into the region.

The ability of vegetation size on echocardiography to predict clinical complications: a meta-analysis.

To clarify whether echocardiographic detection of a vegetation 10 mm or larger in size in patients with left-sided infective endocarditis poses an increased risk for complications, we performed a meta-analysis of English-language publications identified by a computerized search of the key words infective endocarditis and echocardiography. A pooled odds ratio was calculated by using the Robins, Greenland, and Breslow estimate of variance. The pooled odds ratio for increased risk of systemic embolization in the presence of a vegetation >10 mm (10 studies, 738 patients) was 2.80 (95% confidence interval [CI] 1.95 to 4.02; p < 0.01). The odds ratio of requiring valve-replacement surgery (seven studies, 549 patients) was 2.95 (95% CI 1.90 to 4.58; p < 0.01). The odds ratio of death (six studies, 476 patients) was 1.55 (95% CI 0.92 to 2.60; p = 0.10). Thus this analysis supports the hypothesis that echocardiographically detected left-sided vegetations >10 mm pose a significantly increased risk of (1) systemic embolization and (2) a need for valve-replacement surgery than cases where either no or smaller vegetations are detected.

The relationship between the supply of cardiac catheterization laboratories, cardiologists and the use of invasive cardiac procedures in northern New England.

OBJECTIVES: Utilization rates of coronary angiography and cardiac revascularization have been found to vary between areas. This study addresses the relationship between resource supply and procedure rates. METHODS: We compared the association of per capita catheterization laboratories, per capita cardiologists and multi-provider markets (where more than one hospital offers coronary angiography services) with the utilization rates for angiography and cardiac revascularization in northern New England, USA. Administrative data were used to capture invasive cardiac procedures. Small area analyses were used to create coronary angiography service areas. Linear regression methods were used to measure associations between the resource supply and utilization rates. RESULTS: Variation in the use of invasive cardiac procedures was strongly associated with the population-based availability of catheterization facilities and multi-provider markets and unrelated to cardiologist supply or need (as reflected in the hospitalization rates for myocardial infarction). In the multivariate model, an increase of 1 catheterization laboratory per 100,000 population was associated with an increase in the angiography rate of 1.62 per 1000 population; those service areas with multi-provider markets were associated with an additional increase in the angiography rate of 1.27 per 1000 population (R2 = 0.84, P = 0.0006). There was a moderately strong relationship between the catheterization laboratories per capita and the revascularization rates (R2 = 0.43, P = 0.029). Angiography rates were highly associated with cardiac revascularization rates: an increase in the angiography rate of 1 per 1000 population was associated with a 0.46 per 1000 increase in the cardiac revascularization rate (R2 = 0.85, P = 0.0001). CONCLUSIONS: Our work suggests that current efforts to address variation in cardiac procedures through activities such as appropriateness criteria, guidelines and utilization review are misdirected and should be redirected towards capacity, in this case the supply of catheterization facilities.

Evaluation of the significance of a transvalvular catheter on aortic valve gradient in aortic stenosis: a direct hemodynamic and Doppler echocardiographic study.

We studied 18 patients with aortic stenosis undergoing routine cardiac catheterization to determine the effect of a transvalvular catheter on transaortic pressure gradients. By measuring the Doppler gradients before and after the withdrawal of the pigtail catheter, we demonstrated significant increases in the peak instantaneous and mean gradients when the catheter straddled the valve, an effect that was more pronounced with increasing severity of stenosis.

A two-step program of competitive bidding and physician feedback to reduce coronary angioplasty equipment costs.

We demonstrated that a program of competitive bidding among vendors and feedback to operating physicians was successful in reducing percutaneous transluminal coronary angioplasty equipment costs.