Projected Savings to Canadian Provincial Budgets from Reduced Long-Term Care Home Utilization Due to a Disease-Modifying Alzheimer's Treatment.

BACKGROUND: A disease-modifying Alzheimer's treatment could provide budgetary savings to Canadian provinces from a reduction in long-term care home use, yet we do not know the magnitude of those potential savings. OBJECTIVE: We project savings to each Canadian province's budget from 2023 to 2043. DESIGN: Annual savings are projected using a Markov model. We account for reduction in long-term care home use and in use of Alternative Level of Care (ALC) beds, which are hospital beds occupied by care home-eligible patients on the wait list for admission. RESULTS: A treatment that delays disease progression by 40% is projected to avoid 142,507 long-term care home and ALC years, resulting in $17.2 billion cumulative savings across all Canadian provinces, a 21% relative reduction among treatment eligible patients. Average per capita savings were $1,132, ranging from $734 (Alberta) to $2,895 (Prince Edward Island). Cumulative savings could increase to $22.7 billion with enhanced triage of patients in primary care stages and to $25.6 billion if all capacity constraints for diagnosis and treatment were removed. CONCLUSION: A disease-modifying treatment could create budgetary savings from lower long-term care home use, offsetting part of the treatment cost. With the increasing demand for long-term care home beds and the high rates of patients being held in hospitals while wait-listed, such a treatment could additionally provide relief to the overburdened long-term care system in Canada.

Detection Rates of Mild Cognitive Impairment in Primary Care for the United States Medicare Population.

BACKGROUND: Existing evidence points to substantial gaps in detecting mild cognitive impairment in primary care but is based on limited or self-reported data. The recent emergence of disease-modifying treatments for the Alzheimer's disease, the most common etiology of mild cognitive impairment, calls for a systematic assessment of detection rates in primary care. OBJECTIVES: The current study aims to examine detection rates for mild cognitive impairment among primary care clinicians and practices in the United States using Medicare claims and encounter data. DESIGN: Observational study. SETTING: Medicare administrative data. PARTICIPANTS: The study sample includes a total of 226,756 primary care clinicians and 54,597 practices that had at least 25 patients aged 65 or older, who were enrolled in Medicare fee-for-service or a Medicare Advantage plan between 2017 and 2019. MEASUREMENTS: The detection rate for mild cognitive impairment is assessed as the ratio between the observed diagnosis rate of a clinician or practice as documented in the data, and the expected rate based on a predictive model. RESULTS: The average detection rates for mild cognitive impairment is 0.08 (interquartile range=0.00-0.02) for both clinicians and practices, suggesting that only about 8% of expected cases were diagnosed on average. Only 0.1% of clinicians and practices had diagnosis rates within the expected range. CONCLUSIONS: Mild cognitive impairment is vastly underdiagnosed, pointing to an urgent need to improve early detection in primary care.

Estimated Investment Need to Increase England's Capacity to Diagnose Eligibility for an Alzheimer's Treatment to G7 Average Capacity Levels.

BACKGROUND: As disease-modifying Alzheimer's (AD) treatments are becoming available, concerns have been raised that even high-income countries lack the diagnostic capacity to accurately identify eligible patients in a timely manner. OBJECTIVES: We analyze how much NHS England would have to invest in capacity for AD specialists, biomarker testing with PET scans or CSF testing and MRI scans to reach G7 average levels and estimate the effect on wait times in the diagnostic process. DESIGN: Desk research and expert interviews for cost and capacity data. Markov model to estimate wait times. SETTING: NHS England. MEASUREMENTS: AD specialists, and PET and MRI scanners per capita in G7 countries and wait times in England under different investment scenarios. RESULTS: England has the lowest number of PET and MRI scanners and the second-lowest of AD specialists per capita among the G7 countries. An investment of GBP 14 billion over ten years would be needed to reach G7 average levels, of which 31%, 22%, 10%, 37% would be devoted to capacity for memory assessment services, PET scanning, CSF analysis, and MRI scanning, respectively. This investment would reduce estimated average wait times by around 87% between 2023 and 2032. CONCLUSIONS: The NHS England has large gaps in diagnostic capacity for AD. Without substantial investments, AD patients in England would experience substantial wait times and avoidable disease progression.

Health Economic Considerations in the Deployment of an Alzheimer's Prevention Therapy.

INTRODUCTION: As treatments for secondary prevention of Alzheimer's disease (AD) are being studied, concerns about their value for money have appeared. We estimate cost-effectiveness of a hypothetical screening and prevention program. METHODS: We use a Markov model to project cost-effectiveness of a treatment that reduces progression to symptomatic AD by 50% with either chronic treatment until progression to mild cognitive impairment or treatment for one year followed by monitoring with AD blood tests and retreatment with one dose in case of amyloid re-accumulation. Diagnoses would be made with an AD blood test with sensitivity and specificity of 80%, and inconclusive results in 20%. Individuals testing negative would be re-tested in five years and those with inconclusive results in one. RESULTS: The program would generate per-person value of $53,721 from a payer (reduction of direct cost and patient QALY gains) and $69,861 from a societal perspective (adding valuation of reduced caregiver burden). With chronic treatment, it would be cost-effective up to annual drug prices of $7,000 and $10,300, respectively. Time-limited treatment would be cost-effective at annual drug prices of $54,257 and $78,458 from a payer and societal perspective, respectively. Higher specificity of the blood test would decrease cost per person with similar value generation DISCUSSION: A hypothetical prevention treatment for AD could be economically viable from a payer and societal perspective.

Estimates of Current Capacity for Diagnosing Alzheimer's Disease in Sweden and the Need to Expand Specialist Numbers.

BACKGROUND: The emergence of disease-modifying Alzheimer's (AD) treatments provides new hope to patients and families but concerns have been raised about the preparedness of healthcare systems to provide timely access to such treatments because of a combination of a complex diagnostic process and a large prevalent pool. OBJECTIVES: We assess the preparedness of Sweden, a high-income country known for its dementia-friendly policies, to diagnose AD patients eligible for treatment within a six-month window, given current capacity for specialist evaluations and biomarker testing. We calculate the investment requirements for Sweden to achieve this target over a timeframe of 20 years. DESIGN: Desk research to identify data for population, mortality, disease burden, cost of services and current capacity, expert consultation to inform assumptions about patient journey, and use of a Markov model to predict waiting times. The model simulates the patients' journey through different evaluation stages: initial evaluation by a primary care specialist, neurocognitive testing by an AD specialist, and confirmatory biomarker testing with PET scanning or cerebrospinal fluid (CSF) testing. The model assumes specialist appointments and PET scans are capacity constrained, and patients progress from cognitively normal to MCI and from MCI to dementia in the resulting waiting times. MEASUREMENTS: Projected waiting times for diagnosis of eligibility for disease-modifying Alzheimer's treatment from 2023 to 2042 assuming current capacity, assuming 20% of Swedish residents aged 60 years and above would seek an evaluation for cognitive decline. Investments required to scale capacity up to reach target of providing diagnosis within six months on average. RESULTS: Initial average waiting times for AD specialist appointments would be around 21 months in 2023 and remain around 55 months through 2042, as demand would continue to outstrip supply throughout the 20-year model horizon. Waiting times for biomarker testing would be stable at less than four weeks, as patients would be held up in the queue for their first specialist consultations, and use of CSF testing is widely accepted in Sweden. An additional 25% of AD specialists would have to be added above the current growth trend to reduce waiting times to less than 6 months at an average annual cost of approximately 805 million SEK. The increased cost of volume of biomarker testing would amount to about 106 million SEK per year. CONCLUSIONS: At current capacity, the Swedish healthcare system is unable to provide timely diagnosis of patients eligible for disease-modifying AD treatment. Although future diagnostic technologies, such as digital cognitive assessments and blood tests for the AD pathology, might decrease demand for capacity-constrained services, substantial investments will be required to meet a target of less than six months of waiting time for a diagnosis.

Economic Impact of Progression from Mild Cognitive Impairment to Alzheimer Disease in the United States.

BACKGROUND: Limited evidence exists on the economic burden of individuals who progress from mild cognitive impairment (MCI) to Alzheimer disease and related dementia disorders (ADRD). OBJECTIVES: To assess the all-cause health care resource utilization and costs for individuals who develop ADRD following an MCI diagnosis compared to those with stable MCI. DESIGN: This was a retrospective cohort study from January 01, 2014, to December 31, 2019. SETTING: The Merative MarketScan Commercial and Medicare Databases were used. PARTICIPANTS: Individuals were included if they: (1) were aged 50 years or older; (2) had ≥1 claim with an MCI diagnosis based on the International Classification of Diseases, Ninth Revision (ICD-9) code of 331.83 or the Tenth Revision (ICD-10) code of G31.84; and had continuous enrollment. Individuals were excluded if they had a diagnosis of Parkinson's disease or ADRD or prescription of ADRD medication. MEASUREMENTS: Outcomes included all-cause utilization and costs per patient per year in the first 12 months following MCI diagnosis, in total and by care setting: inpatient admissions, emergency department (ED) visits, outpatient visits, and pharmacy claims. RESULTS: Out of the total of 5185 included individuals, 1962 (37.8%) progressed to ADRD (MCI-to-ADRD subgroup) and 3223 (62.2%) did not (Stable MCI subgroup). Adjusted all-cause utilization was higher for all care settings in the MCI-to-ADRD subgroup compared with the Stable MCI subgroup. Adjusted all-cause mean total costs ($34 599 vs $24 541; mean ratio [MR], 1.41 [95% CI, 1.31-1.51]; P<.001), inpatient costs ($47 463 vs $38 004; MR, 1.25 [95% CI, 1.08-1.44]; P=.002), ED costs ($4875 vs $3863; MR, 1.26 [95% CI, 1.11-1.43]; P<.001), and outpatient costs ($16 652 vs $13 015; MR, 1.28 [95% CI, 1.20-1.37]; P<.001) were all significantly higher for the MCI-to-ADRD subgroup compared with the Stable MCI subgroup. CONCLUSIONS: Individuals who progressed from MCI to ADRD had significantly higher health care costs than individuals with stable MCI. Early identification of MCI and delaying its progression is important to improve patient and economic outcomes.

Blood Biomarkers from Research Use to Clinical Practice: What Must Be Done? A Report from the EU/US CTAD Task Force.

Timely and accurate diagnosis of Alzheimer's disease (AD) in clinical practice remains challenging. PET and CSF biomarkers are the most widely used biomarkers to aid diagnosis in clinical research but present limitations for clinical practice (i.e., cost, accessibility). Emerging blood-based markers have the potential to be accurate, cost-effective, and easily accessible for widespread clinical use, and could facilitate timely diagnosis. The EU/US CTAD Task Force met in May 2022 in a virtual meeting to discuss pathways to implementation of blood-based markers in clinical practice. Specifically, the CTAD Task Force assessed: the state-of-art for blood-based markers, the current use of blood-based markers in clinical trials, the potential use of blood-based markers in clinical practice, the current challenges with blood-based markers, and the next steps needed for broader adoption in clinical practice.

One-incision approach for insertion of implantable cardioverter defibrillators.

The placement of a transvenous implantable cardioverter defibrillator (ICD) system through a single infraclavicular skin incision has been a surgical goal for years. The development of a new investigational model of ICD with substantially reduced dimensions (volume, 83 cm3; mass, 132 g) has made the one-incision approach a clinical reality. Between March and September 1993, 4 female and 19 male patients (mean age, 60 +/- 9.6 years; range, 46 to 73 years) underwent implantation of this device for the treatment of ventricular fibrillation (n = 14) or ventricular tachycardia (n = 9). One transvenous lead was placed in the right ventricular apex and another in the left subclavian vein. A subpectoral pocket was formed in the infraclavicular area from the same incision to house the ICD generator and, if necessary, the subcutaneous patch. The mean operation time (81.5 +/- 32.7 minutes; range, 54 to 195 minutes) was significantly shorter than that noted for a previous series made up of patients undergoing traditional transvenous ICD implantations. In 20 patients (87%), endovenous defibrillation without a subcutaneous patch successfully caused externally induced ventricular fibrillation to revert with a mean minimum energy output of 21.9 +/- 3.5 J (range, 12 to 24 J). Endovenous defibrillation was more successful when biphasic (n = 16/17 [94%]) shocks rather than monophasic shocks (n = 4/6 [67%]) were used. No mortality, morbidity, or surgical complications were observed. These results indicate that the one-incision approach and the small size of the ICD generator can substantially facilitate ICD implantation and result in a reduction in the surgical trauma, the operation time, and the amount of material implanted.

[Increased liver density in computed tomography as a result of anti-arrhythmia therapy with amiodarone]. / Erhöhte Leberdichte in der Computertomographie als Folge antiarrhythmischer Therapie mit Amiodaron.

PURPOSE: To assess whether the hepatic density on CT scans of patients receiving amiodarone therapy differs significantly from the hepatic density of a control group not receiving the drug. METHODS: Hepatic density was assessed by CT in 31 patients receiving amiodarone, 7 receiving short-term (12-14 days), 8 receiving mid-term (20-89 days) and 16 receiving long-term therapy (3-26 months), as well as in a control group of 15 patients. RESULTS: Mean liver density of all patients under amiodarone therapy (77.9 +/- 11.7 HU) was significantly higher (p < 0.005) than in the control group (56.6 +/- 2.8 HU). The smallest increase in density was found in patients with short-term therapy (64.8 +/- 3.4 HU; p < 0.05), the greatest increase in patients with long-term therapy (85.0 +/- 8.9 HU; p < 0.001). CONCLUSION: In patients receiving amiodarone therapy, a significantly increased hepatic density on CT scans is observed. This finding has to be considered as a differential diagnosis to other hepatopathies with increased density of the liver.

Surgical therapy for coronary artery disease in patients with a left ventricular ejection fraction of 25% or less.

BACKGROUND: In patients with advanced coronary artery disease (CAD) and markedly decreased left ventricular ejection fraction (EF) symptoms of myocardial ischemia and insufficiency may be complicated by ventricular arrhythmias. Appropriate surgical therapy must be tailored to the individual symptoms. The aim of this study was to compare the different current methods. METHODS: From 9/1990 to 9/1994 138 patients with coronary artery disease and a left ventricular EF of < or = 25% were operated. Patients with dominating Angina pectoris and vital myocardium were revascularized (ACB; n = 17); two of these patients were 12 and 37 months p.o. transplanted. Because of dominating dyspnea, diffuse CAD and missing AP heart transplantation seemed indicated (HTX; n = 102). In two of these patients ventricular assist devices were implanted as a bridge to transplantation; both patients survived. Patients with malign tachycardias received either an implantable cardio-defibrillator (ICD; n = 16) or had arrhythmia surgery (ARS; n = 3). Patients of the HTX-Group were younger (54 vs 60 years; p < 0.05), had more often previous surgery (28% vs 20%) and were in worse conditions (NYHA 3.5 vs 3.0; p < 0.05). RESULTS: The main cause of death after transplantation was multi-organ failure (MOF; 14/102; 13.8%). The best long-term survival (87% after 3.2 years, p < 0.01 vs HTX)-with low average functional classes (NYHA 2.9)-had the patients after ICD implantation. The best quality of live (NYHA 1.1; p < 0.01 vs ICD)-associated with a high mortality due to preoperatively impaired organ-systems (62% operative survival, 57% 4-years survival)-was achieved by transplantation. In patients with a history of ventricular arrhythmias, who are waiting for a transplantation, the implantation of an ICD should be considered. Bypass surgery as well as arrhythmia surgery showed good survival (1-year survival 82% and 66% respectively) and functional results (NYHA 1.7 and 1.5 respectively).

When should measures be updated? Development of a conceptual framework for maintenance of quality-of-care measures.

OBJECTIVE: To document current practices on long-term maintenance of quality measures and to develop a consensus framework to guide the design of maintenance systems. STUDY DESIGN: Survey of 10 organisations developing measures and selected researchers in the USA about current policies and procedures and desirable properties for a comprehensive system for measures maintenance. Panel discussions with all respondents to arrive at consensus recommendations for a framework for maintenance of measures. PARTICIPANTS: Five measures developers, two provider and three purchaser organisations. Six were private sector organisations, two were governmental agencies, and two were accreditation institutions. PRINCIPAL FINDINGS: All organisations had procedures for measures maintenance, but the degree of formalisation of the procedures varied. Three key functions for a measures maintenance system emerged: ad hoc review to deal with unexpected problems; annual maintenance to incorporate changes in coding conventions; and regular re-evaluation to thoroughly review measures at predefined intervals. Importance, scientific soundness, feasibility and usability were universally used as evaluation criteria. The panel discussions yielded a consensus set of recommendations for relationships between maintenance functions, evaluation criteria and measures disposition. CONCLUSIONS: A sufficient degree of implicit consensus was found among leading measures developers to arrive at a consensus framework for policies and procedures for measures maintenance. Although organisations may choose to implement the framework in a way that is most consistent with their mission and structure, it provides guidance regarding which components should be included.

Cardiology and cost control: the ethical challenge for the new millennium.

Government interventions in the health care sector threaten the traditional role of physicians, since they are increasingly forced to consider the cost of medical care when making decisions on behalf of their patients. To prepare themselves for this ethical challenge and to actively participate in the debate about cost containment, physicians need to understand how health economists and politicians view the problem of rising medical costs. This review summarizes some essential facts and findings of the health economics literature that provide the rationale for different approaches to cost containment. The effects of rapidly growing health care cost on the economy are discussed, and improvement of medical technology is identified as the driving force behind this growth. The different policy instruments, which can be employed for cost containment, are explained against this background with an emphasis on Managed Care and global budgets. The outlined concepts are finally discussed in the context of the current debate about the proposed cost containment legislation in Germany.

Limitations of the algorithm to reconfirm ventricular fibrillation in a third-generation implantable cardioverter defibrillator.

We report on inadequate shocks delivered by an ICD for VT converting spontaneously to AF with slow ventricular response. This represents a correct behavior of the reconfirmation algorithm, as the detection of intervals longer than the fibrillation detection interval and shorter than the bradycardia escape interval is required to inhibit the shock.

Right ventricular implantable cardioverter defibrillator lead implantation through a persistent left superior vena cava.

A 60-year-old woman required implantation of an ICD because of a hypotensive ventricular tachycardia refractory to four different antiarrhythmic drugs. Preoperative diagnostics revealed a persistent left SVC as the only major venous return from the upper part of the body to the heart. Under local anesthesia, a tripolar lead was advanced through the left SVC into the right ventricular apex. Following successful testing, an active can ICD device was implanted, which is functioning well during a follow-up period of 9 months.

Randomized crossover comparison of the electrophysiologic and antiarrhythmic efficacy of oral cibenzoline and sotalol for sustained ventricular tachycardia.

We compared the electrophysiologic and clinical effects of oral cibenzoline and sotalol in 12 patients with spontaneous and inducible sustained ventricular tachycardia (VT), using a randomized, open-label, cross-over study. Electrophysiologic studies were performed in the control state, after oral cibenzoline and after oral sotalol, using an incremental dose-titration protocol. Therapy with cibenzoline at the maximum dose level (130-390 mg/day) resulted in complete suppression of VT in 1 of 12 patients (8%). Sotalol (160-320 mg/day) prevented induction of VT in 4 of 12 patients (33%). The effective refractory period (ERP) of the right ventricle was more significantly prolonged with sotalol (p < 0.001) as compared with cibenzoline (p < 0.05). Neither drug prolonged QT duration corrected for frequency (QTc) and cycle length of induced VT, as compared with the control study. Three patients experienced spontaneous VT after cibenzoline administration, and 2 patients experienced incessant VT during programmed electrical stimulation. No patient had a proarrhythmic effect while receiving oral sotalol treatment. Chronic sotalol therapy maintained long-term arrhythmia suppression in all 4 responders at 1-year follow-up. Sotalol appears to have greater efficacy than and a safety profile superior to that of cibenzoline. Drug-related proarrhythmic effects of oral cibenzoline therapy occurred with greater frequency than that associated with other antiarrhythmic drugs. Based on these findings, cibenzoline cannot be recommended for use in patients with VT.

[Anti-arrhythmia and pro-arrhythmia effects of oral cibenzoline therapy in sustained ventricular tachycardia]. / Antiarrhythmische und proarrhythmische Effekte einer oralen Cibenzolintherapie bei anhaltenden ventrikulären Tachykardien.

The efficacy and safety of the new class-I antiarrhythmic drug cibenzoline was assessed in 12 patients with spontaneous and inducible ventricular tachycardia. Programmed ventricular stimulation, 24-h ambulatory electrocardiogram (ECG), and continuous ECG monitoring were performed without antiarrhythmic drugs and after oral administration of 254 +/- 80 mg of the substance. Oral cibenzoline suppressed the induction of tachycardia in only one patient. Induction of tachycardia was more difficult in two patients, unchanged in four patients, and easier in two patients. Cycle length of induced tachycardia and QT-interval corrected for frequency were not changed significantly; effective refractory period of the right ventricle was prolonged. Twenty-four hours of ambulatory monitoring during cibenzoline treatment (n = 9) showed no significant increase in the frequency of ventricular premature complexes. However, spontaneous sustained ventricular tachycardia developed in three patients after initiation of cibenzoline treatment. In two patients, termination of induced ventricular tachycardia was significantly more difficult under cibenzoline; several DC-shocks were required to terminate the tachycardia. Thus, the use of oral cibenzoline in patients with sustained spontaneous and inducible ventricular tachycardias showed a low antiarrhythmic efficacy at programmed stimulation and a high incidence of spontaneous ventricular tachycardia.

Comparison of a unipolar defibrillation system with a dual lead system using an enlarged defibrillation anode.

The unipolar system for transvenous defibrillation, consisting of a single right ventricular lead as the cathode and the device shell as anode, has been shown to combine low defibrillation thresholds (DFTs) and simple implantation techniques. We compared the defibrillation efficacy of this system with the defibrillation efficacy of a dual lead system with a 12-cm long defibrillation anode placed in the left subclavian vein. The data of 38 consecutive patients were retrospectively analyzed. The implantation of an active can system was attempted in 20 patients (group 1), and of the dual lead system in 18 patients (group 2). Both groups had comparable demographic data, cardiac disease, ventricular function, or clinical arrhythmia. The criterion for successful implantation was a DFT of < or = 24 J. This criterion was met in all 18 patients of group 2. The active can system could not be inserted in 3 of the 20 group 1 patients because of a DFT > 24 J. In these patients, the implantation of one (n = 2) or two (n = 1) additional transvenous leads was necessary to achieve a DFT < or = 24 J. The DFTs of the 17 successfully implanted group 1 patients were not significantly different from the 18 patients in group 2 (12.3 +/- 5.7 J vs 10.8 +/- 4.8 J). The defibrillation impedance was similar in both groups (50.1 +/- 6.1 omega vs 48.9 +/- 5.2 omega). In group 1, both operation duration (66.8 +/- 17 min vs 80.8 +/- 11 min; P < 0.05) and fluoroscopy time (3.3 +/- 2.1 min vs 5.7 +/- 2.9 min; P < 0.05) were significantly shorter. Thus, the active can system allows reliable transvenous defibrillation and a marked reduction of operation duration and fluoroscopy time. The dual lead system, with an increased surface area defibrillation anode, seems to be a promising alternative for active can failures.

Hemodynamic deterioration during ICD implant: predictors of high-risk patients.

Defibrillation threshold (DFT) testing during implantation of the cardioverter defibrillator is associated with hemodynamic deterioration and pump failure in many patients. We investigated the influence of DFT testing on cardiac function intraoperatively using a balloon-tipped catheter. In 13 consecutive patients with a nonthoracotomy approach, a mean of 3.4 +/- 1.4 episodes of ventricular fibrillation were induced with an overall ischemic time of 87 +/- 54 seconds. At the end of DFT testing, patients with a left ventricular ejection fraction (EF) of < 30% had significant impairment of cardiac index (1.6 +/- 0.5 L/min/m2 after testing vs 2.2 +/- 0.6 L/min/m2 before the procedure). One patient with severely comprised ventricular function needed prolonged positive inotropic support. The left ventricular function of patients with a preoperative EF > or = 30%, however, was not changed (2.2 +/- 0.5 L/min/m2 after testing and 2.2 +/- 0.5 L/min/m2 before testing). The two groups did not differ with respect to the number of testing episodes, ischemic time, or DFT. Thus patients with a low preoperative EF (< 30%) are threatened by a severe left ventricular deterioration during ICD implantation. Close hemodynamic monitoring with a balloon-tipped catheter is recommended in these patients.

Temperature-controlled radiofrequency catheter ablation of AV conduction: first clinical experience.

A new technique for catheter ablation of atrioventricular (AV) conduction, using temperature-controlled radiofrequency energy and a bipolar asymmetrical electrode configuration, was applied to 12 patients (mean age, 48 +/- 15 years; range, 18-69 years) with medically refractory atrioventricular nodal reentrant tachycardia (AVNRT) or rapid atrial rhythms. The energy source was a 500 kHz generator with automatic power regulation to a preselected temperature of 80 degrees C. A specially designed 7 F bipolar asymmetric thermo-catheter was used for ablation in all cases. The endpoints of the procedure were: first-degree AV block in patients with AVNRT and third-degree block in patients with atrial fibrillation or flutter. Energy was applied over a range of 1-14 times per patient. After a mean follow-up of 8 +/- 4 months, third- or first-degree AV block persisted in eight patients. In comparison to constant-power radiofrequency ablation, where impedance rises are commonly observed, no impedance rise or coating of the electrode occurred during any of the 97 energy applications in this study. Variable wall contact of the electrode was identified in 20 of 97 applications by a slow temperature rise or a drop in temperature and frequent power adjustments. Thus, monitoring temperature and automatic power regulation may help to reduce the total delivered energy. Temperature control during radiofrequency energy avoids coagulum formation and consequently the associated potential hazards of constant-power application.

Defibrillator implantation in a patient with a persistent left superior vena cava.

The implantation of a transvenous cardioverter defibrillator (PCD 7217B) was performed in a patient with a persistent left superior vena cava. The defibrillation electrodes were positioned in the right ventricle and the superior vena cava via the right subclavian vein. A subcutaneous patch had to be implanted at the left lateral chest wall to achieve sufficient defibrillation thresholds. Three weeks later the system had to be removed because of a generator pocket infection. During the second implantation we placed one electrode in the persistent left superior vena cava perpendicular to the electrode in the right ventricle. Using this configuration transvenous defibrillation was possible without an additional subcutaneous patch.