Jens Jung

Tolerability of internal low-energy shock strengths currently needed for endocardial atrial cardioversion.

There seems to be no relation between shock strength and patients tolerability using energy levels currently needed for low-energy internal atrial cardioversion. Every patient felt that the second delivered shock, independent of the amount of energy, was more uncomfortable than the first one, which indicates that psychological conditioning may also play an important role in determining discomfort.

Circannual Variation of Malignant Ventricular Tachyarrhythmias in Patients With Implantable Cardioverter-Defibrillators and Either Coronary Artery Disease or Idiopathic Dilated Cardiomyopathy

We studied the possible relation between the frequency of ventricular tachyarrhythmic events and thermal stress in patients with an implantable cardioverter-defibrillator (ICD) living in a locally limited area under homogeneous climatic conditions. The frequency of tachyarrhythmic events was correlated with the thermal stress level according to the Klima Michel Model, a complete thermophysiologic model that calculates felt-temperature values on the basis of the outdoor temperature and further meteorologic data. During a mean follow-up time of 40 +/- 17 months (range 4 to 72), 761 ventricular tachyarrhythmic events occurred in 50 of 138 consecutive ICD recipients. Analysis of the monthly felt-temperature levels and the mean circannual variation of the registered ventricular arrhythmias suggested that very cold and very hot conditions may be associated with an increased frequency of ventricular tachyarrhythmias. This finding was confirmed by calculation of the sum of tachyarrhythmias on all 2,039 days of the follow-up period divided into 5-degree-step felt-temperature classes. Thus, thermal stress may be 1 factor triggering the occurrence of ventricular tachyarrhythmias in patients with cardiac disease and suppressed cardiac function. Part of the increase in cardiac mortality under above-average hot and cold atmospheric conditions may be attributed to ventricular arrhythmic events.

Low-energy transvenous cardioversion of atrial fibrillation using a single atrial lead system.

Atrial Cardioversion Using a Single Atrial Lead System. Introduction: Clinical studies have shown that electrical conversion of atrial fibrillation (AF) is feasible with transvenous catheter electrodes at low energies. We developed a single atrial lead system that allows atrial pacing, sensing, and defibrillation to improve and facilitate this new therapeutic option.

Effectiveness and Safety of Carotid Artery Stenting for Significant Carotid Stenosis in Patients With Contralateral Occlusion (from the German ALKK-CAS Registry Experience)

Data on the safety of carotid artery stenting (CAS) in a large number of unselected patients with contralateral occlusion and significant ipsilateral stenosis are less known. Accordingly, we evaluated 3,137 patients undergoing CAS who were enrolled in a German Registry from 2000 to 2008 and compared the clinical features and in-hospital outcomes of those with and without contralateral carotid occlusion. Contralateral carotid occlusion was present in 191 patients (6.1%) undergoing CAS. Despite the similar age of the patients with and without contralateral carotid occlusion, those with contralateral occlusion had a greater prevalence of co-morbidities, complex carotid stenosis, and greater number of focal neurologic lesions on the contralateral side. The incidence of in-hospital events, including death (1.0% vs 0.5%), ipsilateral major stroke (1.1% vs 1.1%), death or major ipsilateral stroke (1.6% vs 1.4%), ipsilateral transient ischemic attack (2.7% vs 2.5%), myocardial infarction (0.0% vs 0.1%), and reintervention (0.5% vs 1.1%), was low and was not significantly different between those with and without contralateral occlusion (p >0.05 for all comparisons). Among patients with carotid occlusion, major ipsilateral stroke (2.2%), death (2.2%), and a combination of these 2 events (3.3%) were observed exclusively in symptomatic patients with no event in asymptomatic patients. In conclusion, our data from a large number of patients undergoing CAS in a recent contemporary community-based practice attests to the low risk of periprocedural events among patients with contralateral carotid occlusion supporting CAS as an attractive option for the treatment of these patients.

Antitachycardia Pacing in Patients with Implantable Cardioverter Defibrillators: How Many Attempts Are Useful?

The purpose of this study was to determine the termination and acceleration rates for 1 to 6 attempts of antitachycardia pacing (ATP) delivered by ICD in order to terminate spontaneously occurring VTs. Twenty‐four ICD recipients with active ATP programs, including a maximum of six ATP sequences and spontaneously occurring VTs during follow‐up, were investigated. During a mean follow‐up of 42 ± 15 months (range, 17–63 months) 413 spontaneous VT episodes (17 ± 14; range, 1–49 per patient) resulting in appropriate ATP delivery by the ICD occurred. ATP successfully terminated 328 episodes (80 %) with a mean number of 1.6 ± 1.1 pacing sequences. Eighty episodes (19%) were accelerated by ATP and 5 (1%) were unresponsive to ATP. The ATP success decreased until the third ATP sequence (59%→ 31%→ 24%), but increased again in the fourth to sixth attempt (46%→ 46%→ 29%). The acceleration rate increased from sequence one to sequence three (8%→ 13%→ 28%), but decreased significantly in further ATP attempts (19%→ 0%→ 0%). The mean time delays until redetection or termination after 4, 5, and 6 attempts of ATP were 22 ± 5 seconds, 37 ± 2 seconds, and 41 ± 9 seconds, respectively. Nine patients (37%) used ≥3 ATP attempts during follow‐up and all of them had a therapeutic benefit from it. Five out of 13 VTs (38%) treated with ≥4 attempts could ultimately be terminated by ATP. The results of this study demonstrate that the first ATP sequence is the most effective and that > 4 ATP attempts may be useful in a minority of patients. There seems to be a low risk of VT acceleration by the fourth to sixth ATP sequence. Because of the associated time delay, a high number of ATP attempts should only be programmed in patients with hemodynamically well‐tolerated stable VTs.

Assessment of heart rate variability by using different commercially available systems

The results of heart rate variability analysis of the same Holter tape by using 4 different commercially available systems are statistically incomparable. This might have important implications when projecting and evaluating clinical trials.

Incidence and clinical significance of short-term recurrent ventricular tachyarrhythmias in patients with implantable cardioverter-defibrillator.

Aims of the present study were (1) to investigate the clinical significance of short-term recurrent tachyarrhythmias (STRTs) in ICD recipient, (2) to identify basic characteristics of the subgroup of patients with STRTs and (3) to compare the frequency and circadian pattern of single arrhythmic events and STRTs. We reviewed data from 119 consecutive patients with late generation ICD. All registered spontaneous ventricular tachyarrhythmias were divided into STRTs (defined as two or more consecutive episodes separated by < or =1 h of sinus rhythm) and single events. During a mean follow up of 36+/-18 months (range 2-67 months) 1849 ventricular arrhythmic events were detected in 57 out of 119 ICD recipients (48%). 202 STRTs consisting of 1128 single detection (6+/-7/STRT, range 2-52) occurred in 34/57 patients (60%; 6+/-6 per patient, range 1-21). Recurrent ventricular tachycardias before device implantation and a high number of single arrhythmic events during follow-up distinguished patients with STRTs. Cardiac mortality was significantly higher in patients with STRTs (26 vs. 4%, P<0.05). The majority of both single episodes and STRTs were registered between 8 a.m. and noon and in the evening. This study reveals a high incidence of STRTs in ICD recipients with spontaneous tachyarrhythmias during follow-up and identifies STRTs as prognostic significant events. Comparable circadian variations suggest that similar triggering factors may be involved in the genesis of STRTs and single tachyarrhythmias.

Low Energy Transvenous Cardioversion of Short Duration Atrial Tachyarrhythmias in Humans Using a Single Lead System

The purpose of this study was to investigate the efficacy and safety of atrial cardioversion using an endocardial single lead system presently used for ventricular defibrillation. The study population consisted of 26 recipients of an ICD in combination with a conventional endocardial single lead system with the proximal spring electrode as anode in the SVC and the distal as cathode in the apex of the RV. Atrial tachyarrhythmias were induced by right atrial burst pacing. If the arrhythmia sustained > 1 minute, biphasic shocks synchronized with the R wave were delivered using the implanted device, beginning with an energy of 4 J. If 4 J failed to terminate the arrhythmia, energy was increased stepwise, if the first shock was successful, a step‐down testing was performed after reinduction of atrial tachyarrhythmias. The mean atrial defibrillation threshold was 2.3 ± 1.2 J (range, 0.5–5 J). A total of 154 shocks were delivered and no adverse effects were observed. The mean defibrillation threshold for atrial flutter was somewhat lower than that for AF (1.8 ± 1 J vs 2.7 ± 1.4 J, P = 0.08). There was no correlation between the atrial defibrillation threshold and a history of previously occurring atrial tachyarrhythmias, the kind of the underlying heart disease, a prescription of antiarrhythmic drugs, the dimension of the LA, the LVEF, or the ventricular DFT. Internal atrial cardioversion of short duration atrial tachyarrhythmias using a transvenous single lead system designed for ventricular defibrillation is feasible and safe at low energies, and may have important clinical applications.

Antitachycardia Pacing in Patients With Implantable Cardioverter-Defibrillators: Inverse Circadian Variation of Therapy Success and Acceleration

We analyzed spontaneous ventricular tachycardias treated by antitachycardia pacing during long-term follow-up in 138 recipients of an implantable cardioverter-defibrillator. An inverse circadian variation of the antitachycardia pacing termination and acceleration rates with the worst antitachycardia pacing success during the time period with the highest episode frequency (morning hours) was demonstrated.

Atrial Defibrillation: Can Modifications in Current Implantable Cardioverter-Defibrillators Achieve This?

Atrial fibrillation (AF), the most common arrhythmia resulting in hospital admission, is a major health problem. The limited efficacy of antiarrhythmic drugs to control this rhythm disorder and their potential proarrhythmic risk led to the development of new techniques to ameliorate the treatment of AF. Transvenous atrial defibrillation using endocardial electrodes has been shown to be effective at low energy levels. An implantable atrial defibrillator could be a potentially valuable treatment option for patients with paroxysmal AF that is medically refractory. Research is currently under way to investigate several critical issues concerning this new therapeutic concept: long-term efficacy, safety, patients tolerance, and an acceptable cost/benefit ratio. It is well known that AF often complicates the use of the implantable cardioverter-defibrillator (ICD) for ventricular tachyarrhythmias. Therefore, it would seem desirable to implement the capability for atrial defibrillation into current ICD systems. It has been shown that atrial defibrillation, using endocardial lead configurations specifically designed for ventricular defibrillation, is feasible at energies well within the capabilities of current ICD technology. Further research is needed to evaluate if some enhancement of the lead configuration in combination with possible advanced technology could reduce the atrial defibrillation threshold to a well tolerated level as a prerequisite for automated atrial defibrillation, in ICD recipients with concomitant paroxysmal AF.