Ist die intraoperative ICD-Testung noch nötig?

Intraoperative ICD-testing is traditionally performed in many hospitals in order to ensure reliable sensing, detection, and defibrillation of induced ventricular fibrillation. The technical progress of defibrillators allows rapid detection and delivery of high energy shocks which defibrillates effectively in the vast majority all patients at implant. This review describes arguments pro and contra of systematic testing of the defibrillation threshold in all patients. Many reasons argue against testing in all patients: experimental considerations, patients’ specific and nonspecific factors, e.g., underlying severity of cardiac disease, ischemia, and medication, as well as factors specific to the ICD system, e.g., implanted type and location of electrodes and active cans. Finally, the testing method is very important, since it bears the risk of false negative test results because the a priori probability of a positive test result is >95%. Therefore, data from prospective randomized studies are necessary in order to abandon the tradition of ICD-testing on an evidence-based background.     

Ventricular fibrillation in intra-atrial cardioversion of atrial fibrillation

Recently intra-atrial defibrillation has become an interesting alternative to external defibrillation and drug therapy for the treatment of atrial fibrillation. Low-energy intra-atrial defibrillation can be used to restore sinus rhythm f.ex. after a failed external cardioversion or during an electrophysiologic study when the administration of antiarrhythmic drugs should be avoided. Additionally this new technique has led to the development of implantable atrial defibrillators for the treatment of selected patients suffering from chronic atrial fibrillation. Intra-atrial defibrillation seems to be a highly effective and safe method, but little experience exists concerning the outcome so far. Especially the potential risk of inducing ventricular pro-arrhythmia is subject of current controversy. We report the case of a 79-year-old patient suffering from WPW syndrome with a concealed bypass tract who was subject to an intra-atrial defibrillation during an electrophysiologic study. At the beginning of the study atrial fibrillation could be converted to sinus rhythm by a single low-energy atrial defibrillation (3 J.). After a short period of time a second intra-atrial defibrillation had to be performed in the same way because of recurrent atrial fibrillation. By this atrial shock ventricular fibrillation was induced, so that high energy external defibrillation became necessary. Analyzing the ECG a correct R-wave synchronization was found, but a rather short preceding RR interval (252 ms). In conclusion, low energy atrial defibrillation is gaining importance as a highly effective new technique to restore sinus rhythm in patients suffering from atrial fibrillation resistant to conventional therapies. Nevertheless potential risks have to be considered such as the induction of ventricular pro-arrhythmia. Therefore, a correct R-wave synchronization is obligatory and shock delivery should be withheld after short RR intervals. Future prospective randomized studies will have to show whether this new technique is really safe enough and superior to the conventional methods for restoring sinus rhythm in patients suffering from atrial fibrillation.     

Breast Carcinoma Metastatic to the Choroid: Analysis of G7 Patients

Two hundred fifty patients with breast carcinoma had ocular examinations between 1973 and 1980. One hundred fifty-two patients were referred because of ocular symptoms or signs, and 98 were asymptomatic. Of the symptomatic patients, 58 had choroidal metastases; nine of the asymptomatic patients with stage IV metastatic breast cancer had choroidal involvement (9.2%). For the 67 patients with metastases, the median age at ocular diagnosis was 51 years. The median interval from primary to choroidal metastases was three years. Survival after ocular diagnosis ranged from one week to four years, with a median of nine months. Among the 67 patients, choroidal tumor deposits occurred bilaterally in 27 patients (40.3%), in 18 right eyes (26.9%), and in 22 left eyes (32.8%). Irradiation led to stabilization or improvement in visual acuity in virtually all cases. Patients in whom acuity was not threatened were observed on medical therapy. Four of these patients eventually required irradiation for increasing disease. Choroidal metastases tended to follow pulmonary dissemination, and to occur with or before central nervous system disease. Choroidal metastases are a common, treatable event in breast carcinoma and may represent the smallest detectable clinical lesion.     

In vitro experiments with an injection technique for cup fixation in total hip arthroplasty

Summary A new technique has been developed to position the cup rigidly into the acetabulum during total hip joint replacement. After positioning the flanged cup on the acetabulum by means of screws, a low-viscosity cement is injected through a hole in the rim of the cup. A comparison with the standard cementing technique was made on the basis of in vitro experiments. For this purpose a mold was constructed to produce castings simulating the human acetabulum. The distribution of the cement, the pressure developed in the acetabulum, and the penetration of the cement are compared for the two cementing techniques.     

Addition of a defibrillation electrode in the low right atrium to a right ventricular lead does not reduce ventricular defibrillation thresholds

Transvenous unipolar active can defibrillation systems have proven to be effective in treating ventricular tachyarrhythmias. However, a further reduction of ventricular defibrillation thresholds (V-DFT) would increase the longevity, reduce the size of pulse generators, and help to avoid additional leads in patients with inacceptable high V-DFTs. In a finite difference computer model, the extension of the right ventricular (RV) defibrillation coil into the low right atrium led to a 40% reduction of unipolar V-DFT. To evaluate this finding, we conducted a prospective, randomized study in 11 patients receiving an ICD. Extension of the RV electrode was simulated by adding a second coil placed in the low right atrium with the same polarity. Using a binary search protocol, V-DFT was determined with and without the additional electrode in each patient. Total shock impedance was significantly lower in the two coil (low RA) configuration, compared to the single coil (RV) configuration. Corresponding values were 49.9 +/- 6.7 Ohm and 61.1 +/- 9.3 Ohm, respectively (P < 0.01, paired t-test). However, there was no reduction, but even a nonsignificant increase in V-DFTs. Mean V-DFT in the RV configuration was 12.0 +/- 5.6 J and 16.3 +/- 7.8 J in the low RA configuration (P = 0.09, paired t-test). Despite a reduction in total impedance, the addition of a defibrillation coil in the low right atrium does not reduce ventricular defibrillation thresholds.     

Electrophysiology and long-term efficacy of pentisomide in patients with supraventricular tachycardia.

The electrophysiologic effects of pentisomide were investigated after intravenous (5 mg/kg) and oral (900-1200 mg three times a day) application in 9 patients with drug refractory atrioventricular nodal tachycardia and 6 patients with orthodromic atrioventricular re-entrant tachycardia. Pentisomide did not change sinus cycle length, effective refractory period of the right ventricle and the atrioventricular node. AH, HV interval, effective refractory period of the right atrium, QRS duration and QTc duration were (p less than or equal to 0.01) increased. Tachycardia cycle length was only increased after intravenous application of pentisomide, antegrade effective refractory periods of the accessory pathways and shortest fully pre-excited R-R intervals during atrial fibrillation were increased after the oral treatment phase (p = 0.054). Intravenous pentisomide prevented tachycardia in 6/9 patients with atrioventricular nodal tachycardia and in 2/6 patients with atrioventricular re-entrant tachycardia. If intravenous pentisomide did not prevent induction of the tachycardia, oral pentisomide was not effective either. During long-term follow-up 2/7 patients with atrioventricular nodal tachycardia and 1/4 patient with atrioventricular re-entrant tachycardia had a recurrence. Long-term treatment with pentisomide had to be discontinued because of possible side effects in 2 patients. It is concluded, that the electrophysiological effects of pentisomide are similar to those of flecainide and propafenone.     

Management of atrial fibrillation in patients with heart failure.

Atrial fibrillation (AF) and chronic heart failure (CHF) are two major and even growing cardiovascular conditions that often coexist. However, few data are available to guide treatment of AF in patients with CHF. This review summarizes current literature concerning the following topics: (i) prognostic relevance of AF in patients with CHF, (ii) relevance and strategies of rhythm and rate control in patients with AF and CHF, and (iii) options for prevention of AF in patients with ventricular dysfunction. In conclusion, AF is associated with increased mortality in CHF patients. However, it is not clear whether there is a causal relationship. Emerging strategies to prevent the occurrence of AF are promising tools that might improve quality of life and survival in patients with CHF.