Dieter Zenker

Intrathoracic impedance monitoring to detect chronic heart failure deterioration: Relationship to changes in NT-proBNP

An alert algorithm, based on intrathoracic impedance monitoring, has been incorporated into a cardiac resynchronisation device (CRT) to detect pulmonary fluid accumulation, and to audibly alert patients to decompensating chronic heart failure (CHF).

Cardiac resynchronization therapy and atrial overdrive pacing for the treatment of central sleep apnoea

The combined therapeutic impact of atrial overdrive pacing (AOP) and cardiac resynchronization therapy (CRT) on central sleep apnoea (CSA) in chronic heart failure (CHF) so far has not been investigated. We aimed to evaluate the effect of CRT alone and CRT + AOP on CSA in CHF patients and to compare the influence of CRT on CHF between CSA positive and CSA negative patients.

Renal function and safety of heart transplant recipients switched to mycophenolate mofetil and low-dose cyclosporine

BACKGROUND We evaluated cyclosporine (CSA) dose reduction and mycophenolate mofetil (MMF) treatment versus maintained CSA dosage and azathioprine (AZA) in HTX regarding renal function and safety from CSA nephrotoxicity (creatinine > 1.7 mg/dL). METHODS Fourteen recipients (group 1: 12 men, 2 women) with CSA-based immunosuppression (plus azathioprine and/or steroids) were started on 2000 mg MMF/d. Azathioprine was discontinued and CSA tapered to trough whole blood levels of 70 to 120 microg/L. Ten recipients (group 2: seven men, three women) were maintained on their CSA dosages. Creatinine clearance, serum creatinine, uric acid, urea nitrogen, and rejection were monitored. RESULTS Mean age was 58 (range 44 to 69 years) and 48 years (range 24 to 61 years) in groups 1 and 2, respectively. In group 1 creatinine fell from 2.7 +/- 0.8 to 1.9 +/- 0.5 mg/dL (baseline vs control 2: P =.001); uric acid and urea nitrogen remained constant. CSA levels decreased from 173 +/- 56 to 110 +/- 33 microg/L (P =.02). In group 2 creatinine (2.4 +/- 0.7 vs 2.3 +/- 0.5 mg/dL), uric acid, urea nitrogen, and CSA levels remained constant. Comparison between groups showed higher creatinine clearance (50 +/- 18 vs 29 +/- 14 mL/min; group 1 vs group 2: P =.02), lower CSA levels (110 +/- 33 vs 161 +/- 35 microg/L; P <.001) and a trend toward lower serum creatinine (1.9 +/- 0.5 vs 2.3 +/- 0.5 mg/dL, P =.077). There were two rejections >/= 1B according to ISHLT in the study and four in the control group. Two deaths occurred in each group. CONCLUSIONS Conversion from AZA to MMF after CSA reduction improves creatinine clearance in HTX recipients and reduces serum creatinine. No negative effect on patient safety was identified by rejection rate or survival.

Indications for reoperation late after correction of tetralogy of Fallot.

OBJECTIVE Correction of tetralogy of Fallot has excellent long-term results. The present retrospective study investigates the indications for reoperation late after corrective surgery. METHODS Data from 914 consecutive cases who underwent correction of tetralogy of Fallot in our department between 1960 and 2002 were retrospectively reviewed and analysed. In 91 patients, a total of 102 reoperations were performed late after repair. RESULTS The mean time interval between corrective surgery and the first reoperation was 12.8 years. The main indication for reoperation was residual ventricular septal defect in nearly half of the cases, mostly isolated, but also in combination with a right ventricular outflow tract aneurysm or pulmonary stenosis. One-fourth of reoperated patients underwent a procedure on their pulmonary artery or pulmonary valve: replacement of pulmonary valve, replacement of primary implanted pulmonary artery conduits with or without concomitant surgery, and surgery for isolated peripheral pulmonary stenosis. The remaining indications were right ventricular outflow tract aneurysms and others. Aneurysms of the right ventricular outflow tract were seen mostly after the use of autologous - untreated - pericardial patch in 18 of 21 cases. CONCLUSION The number of reoperations for residual ventricular septal defect decreased during the study period. The primary use of conduits led to an increased number of reoperations for conduit exchange due to degeneration or failure. Use of an untreated autologous pericardial patch for enlargement of the right ventricular outflow tract should be avoided due to increased risk for aneurysm formation.

URODILATIN (INN : ULARITIDE) AS A NEW DRUG FOR THE THERAPY OF ACUTE RENAL FAILURE FOLLOWING CARDIAC SURGERY

1. Acute renal failure is a severe complication following major cardiac surgery.

Randomized Clinical evaluatiON of wireless fluid monitoriNg and rEmote ICD managemenT using OptiVol alert-based predefined management to reduce cardiac decompensation and health care utilization: The CONNECT-OptiVol study

AIMS The CONNECT-OptiVol study is designed to investigate whether wireless fluid monitoring using OptiVol alerts as well as implantable cardioverter-defibrillator (ICD) remote monitoring (RM) reduces cardiac decompensations and health care utilization in ICD patients, as compared to standard clinical care. METHODS Patients undergoing implantation of wireless telemetry-enabled dual chamber (ICD-DR) or cardiac resynchronization therapy/defibrillator (CRT-D) devices with the OptiVol feature are eligible for the study. In a randomized fashion, OptiVol function, its audible alert as well as its remote alert, and other ICD RM alerts are switched ON or OFF. The primary study objective is to estimate an improvement of heart failure status. The primary endpoint is measured as a prolongation of the time to first hospitalization due to worsened heart failure. The secondary objectives are to estimate: a reduction of the time from event to clinical decision, a reduction of the rate of health care utilization, and improved quality of life (QoL) measures (secondary endpoints). The study is designed as a single center pilot study with 180 patients randomized 1:1 to the two study arms. CONCLUSION The CONNECT-OptiVol study aims to answer whether wireless fluid monitoring integrated into RM may reduce cardiac decompensations and health care utilization in ICD patients. The results can be used to adequately power future studies evaluating the benefit of these features. Study enrollment has been completed, and follow-up is expected to be finished in September 2012.

Subthreshold Test Pulses Versus Low Energy Shock Delivery to Estimate High Energy Lead Impedance in Implanted Cardioverter Defibrillator Patients

VOLLMANN, D., et al.: Subthreshold Test Pulses Versus Low Energy Shock Delivery to Estimate High Energy Lead Impedance in Implanted Cardioverter Defibrillator Patients. The high energy lead impedance is valuable for detecting lead failure in ICDs, but until recently shock delivery was necessary for high energy impedance measurement. This study compared the use of subthreshold test pulses and low energy test shocks to estimate the high energy impedance. Immediately after implantation of Ventak Prizm ICDs in 29 patients, the lead impedance was measured with five subthreshold (0.4 μJ) test pulses, 5 low energy (1.1 J) shocks, and two to three high energy (16 ± 4.5 J) shocks. The mean impedances measured using high energy shocks, low energy shocks, and subthreshold pulses were 42.0 ± 7.3 Ω, 46.5 ± 8.1 Ω , and 42.4 ± 7.1 Ω , respectively. The impedances measured using high and low energy shocks differed significantly (P <0.0001) , while those obtained by high energy shocks and low energy pulses did not (P = 0.63) . According to the Pearson correlation coefficient, the impedance measurements with subthreshold pulses and low energy shocks were both closely correlated(P < 0.0001)with impedance values determined with high energy shocks. However, while the impedance values tended to be higher when measured with low energy shocks, the concordance correlation coefficient (c) was higher for subthreshold test pulse versus high energy shock(c = 0.92)than for low versus high energy shock(c = 0.73). Furthermore, the intraindividual variability of impedance measurements was lower with subthreshold pulse measurements than with low energy shocks. Compared with low energy shocks, impedance measurement with subthreshold pulses has higher reproducibility and a higher correlation with the impedance obtained by high energy shock delivery. Safe and painless high energy impedance estimation with subthreshold pulses might, therefore, help to detect ICD lead failure during routine follow‐up. (PACE 2003; 26:[Pt. II]:457–460)

Worldwide evaluation of a defibrillation lead with a small geometric electrode surface for high-impedance pacing

Abstract Background Pacing leads with a small electrode surface for high-impedance stimulation have been shown to prolong pacemaker longevity, but no sufficient data is available on the safety and feasibility of a defibrillation lead with this novel design. Methods We evaluated the clinical performance of a tined, steroid-eluting defibrillation lead with a small electrode surface area (model 6944) in a prospective multicenter study. A total of 542 patients with conventional indications for an implantable cardioverter defibrillator were randomized 1:1 to receive either the model 6944 or a tined, steroid-eluting defibrillation lead with a conventional sized electrode surface area (model 6942). Device performance and electrical parameters were evaluated at implant and 1, 3, 6, and 12 months thereafter (mean follow-up 11.3 ± 5.6 months). Results Baseline characteristics, lead implant success rates, and defibrillation thresholds did not differ significantly between the 2 groups. While pacing thresholds did not differ significantly during follow-up, pacing impedance was approximately twice as high in the model 6944 as in the model 6942 lead (P Conclusions The use of a defibrillation lead with a small electrode surface for high-efficiency pacing is safe and feasible and increases pacing impedance without significantly compromising clinical performance.

Acute and long-term feasibility of contralateral transvenous lead placement with subcutaneous, pre-sternal tunnelling in patients with chronically implanted rhythm devices.

AIMS A growing number of patients with implanted rhythm devices require new or additional leads, e.g. in cases of electrode defect or planned device upgrade. If the ipsilateral subclavian vein is occluded, transvenous electrode placement from the contralateral side with subcutaneous, pre-sternal lead tunnelling (TUN) is one potential option that has been described in anecdotal reports. The aim of this retrospective study was to determine the acute and long-term feasibility of this approach. METHODS AND RESULTS We identified 18 subjects (67% male, 66±14 years) who underwent TUN at our institution between the years 1995 and 2009. Implantation protocols and patient files were reviewed for peri-operative complications and long-term lead performance. Furthermore, patients were interviewed for symptoms related to the tunnelled lead. Twenty transvenous leads (seven implantable cardioverter defibrillator leads; five left ventricular, four right ventricular, four right atrial pace/sense electrodes) were successfully tunnelled without significant peri-operative complications. The follow-up duration was 29±36 (3-162) months. Electrical parameters remained stable in 95% (19/20) of the tunnelled leads. In one right ventricle pace/sense lead, ventricular oversensing was documented 10 months after TUN, and the lead was replaced because a structural defect could not be excluded. Five patients died without causal relationship to the procedure 4-48 months after TUN. One patient reported discomfort related to the tunnelled lead. CONCLUSION Contralateral transvenous lead implantation with subcutaneous, pre-sternal TUN appears to be a feasible option in selected patients with an implanted rhythm device and ipsilateral subclavian vein occlusion.

1-year performance of a defibrillation lead with a small electrode surface for high impedance pacing: a randomized, controlled study.

VOLLMANN, D., et al.: 1‐Year Performance of a Defibrillation Lead with a Small Electrode Surface for High Impedance Pacing: A Randomized, Controlled Study. A small electrode surface reduces pacing current drain and can extend generator longevity. The study evaluated the performance of a tined, quadripolar defibrillation lead (model 6944) that has a small‐surfaced, steroid‐eluting electrode tip for high impedance pacing. In a prospective, controlled study, 34 patients with conventional ICD indications were randomized one to one to receive the high impedance model 6944 or a tined defibrillation lead with a conventional sized, steroid‐eluting electrode tip model 6942. Lead performance was evaluated at implant, prior to hospital discharge, and 1, 3, 6, and 12 months thereafter. Baseline characteristics did not differ significantly between patients implanted with lead model 6942 (n = 16) or model 6944 (n = 17). One patient randomized to receive the model 6942 was excluded from the study and was implanted with an active‐fixation lead after stable lead positioning was neither possible with the 6942 nor with the 6944 electrode. No other lead related adverse events were observed. At implant, there were no significant differences between pacing thresholds, sensing performance, defibrillation impedances, and defibrillation thresholds in both groups, but pacing impedance of the model 6944 (988.6 ± 217.7 Ω) was approximately twice as high as in the model 6942 (431.7 ± 83.7 Ω; P < 0.0001). This difference remained highly significant throughout the observation period of 12 months, while R wave amplitudes and pacing thresholds remained equal in both lead models. The use of a tined defibrillation lead with a small, steroid‐eluting electrode tip appears safe and results in a high pacing impedance without compromising system performance.