[Leadless pacemakers and subcutaneously implantable cardioverter defibrillators]. / Sondenlose Schrittmacher und subkutan implantierbare Kardioverter-Defibrillatoren.

Although pacemakers and implantable defibrillators have become the standard treatment of bradycardic and tachycardic arrhythmias, long-term complications caused by the transvenously inserted pacing and defibrillation leads, such as electrode fracture, lead infection and tricuspid valve insufficiency are not uncommonly observed. Therefore, leadless pacemakers and purely subcutaneously implantable cardioverter defibrillators (S-ICDs) have been developed in recent years, which are implanted without transvenous electrodes with the aim to reduce long-term complications with these devices; however, currently available leadless pacemakers are limited to single chamber stimulation and S­ICDs are limited to pure defibrillation without antibradycardic, antitachycardic pacing or cardiac resynchronization capabilities. Thus, these devices cannot yet be used as multichamber pacemakers or defibrillators even though in these circumstances a higher complication rate is to be expected due to the multiple number of transvenous leads. This article summarizes the current state of knowledge on leadless pacemakers and ICDs, discusses the limitations of these devices and provides an outlook into their future development.

An implantable carotid sinus baroreflex activating system: surgical technique and short-term outcome from a multi-center feasibility trial for the treatment of resistant hypertension.

OBJECTIVES: To assess perioperative outcomes and blood pressure (BP) responses to an implantable carotid sinus baroreflex activating system being investigated for the treatment of resistant hypertension. METHODS: We report on the first seventeen patients enrolled in a multicenter study. Bilateral perivascular carotid sinus electrodes (CSL) and a pulse generator (IPG) are permanently implanted. Optimal placement of the CSL is determined by intraoperative BP responses to test activations. Acute BP responses were tested postoperatively and during the first four months of follow-up. RESULTS: Prior to implant, BP was 189.6+/-27.5/110.7+/-15.3 mmHg despite stable therapy (5.2+/-1.8 antihypertensive drugs). The mean procedure time was 202+/-43 minutes. No perioperative strokes or deaths occurred. System tests performed 1 or up to 3 days postoperatively resulted in significant (all p < or = 0.0001) mean maximum reduction, with standard deviations and 95% confidence limits for systolic BP, diastolic BP and heart rate of 28+/-22 (17, 39) mmHg, 16+/-11 (10, 22) mmHg and 8+/-4 (6, 11) BPM, respectively. Repeated testing during 3 months of therapeutic electrical activation demonstrated a durable response. CONCLUSIONS: These preliminary data suggest an acceptable safety of the procedure with a low rate of adverse events and support further clinical development of baroreflex activation as a new concept to treat resistant hypertension.

[Left ventricular pacing and CRT. What CV lead fits into which vein?]. / Linksventrikuläre Stimulation und CRT -- Welche Elektrode passt zu welcher Vene?

The experience of 579 patients with left ventricular pacing specific characteristics of various leads and lead types for left ventricular stimulation are reported. After describing the advantages of coronary vein (CV) leads versus epicardial lead usage for left ventricular stimulation, commercially available CV leads are introduced and discussed. Since there is no universally applicable CV lead, the individual optimal lead choice and the sequelae of erroneous lead choice are described in typical clinical examples.

[Acute hemodynamic effects]. / Akute hämodynamische Effekte.

Several studies on the acute effect of cardiac resynchronization in patients with advanced heart failure (HF) and left bundle branch block (LBBB) have shown that left and biventricular stimulation increase pulse pressure and contractility, while patients with a QRS complex <150 ms may deteriorate during stimulation. Patients with LBBB, severe HF and a QRS width >150 ms underwent right, left and biventricular stimulation at different AV delays. Acute response was defined as > or =10% pulse pressure increase. 165 of 188 patients (88%) in sinus rhythm (47 women, mean age 62.5+/-10 years, ejection fraction 23+/-8%, NYHA class 3.1+/-0.3) were regarded acute responders. 10% of 103 patients with dilated cardiomyopathy and 16.5% of 79 patients with coronary artery disease were considered non-responders. 29 patients (81%) with 2 posterolateral veins were acute responders with 10 of them (33%) being responders in only one vein. 54 patients had a higher pulse pressure increase (10.7+/-10.6%) with atrio-left ventricular stimulation, 48 patients with atrio-biventricular stimulation (9.8+/-6.4%). At one-year follow-up, heart failure had significantly (p<0.0001) improved from NYHA class 3.1+/-0.4 to 2.1+/-0.7, VO(2)peak from 12.7+/-2.8 to 15.9+/-3.6 ml/min/kg. Left ventricular enddiastolic diameter being an indicator of reverse remodeling decreased from 80.5+/-10.5 to 73.3+/-13 (p<0.0001). Hemodynamic testing before CRT allows for the identification of acute non-responders as well as the best mode and site of stimulation and the optimal atrioventricular delay in responders.

Coronary vein leads for cardiac pacing in patients with tricuspid valve replacement.

BACKGROUND: Because after tricuspid valve replacement (TVR) the transvenous implantation of endocardial leads is contraindicated, myocardial screw-in leads were used to ventricular pacing. Recently available coronary vein (CV) leads are stimulating the left ventricle epicardially and can be implanted transvenously, too. METHOD AND RESULTS: We implanted these leads in patients (pts) with TVR (n = 7) or after valve repair (n = 1) without complications. In 7 pts we used bended CV leads with a microporous tip and only in one pt a CV lead with a stimulation via metal ring. The stimulation thresholds (ST) were stable in all pts. CONCLUSIONS: The use of CV leads offers a minimal invasive approach for permanent cardiac stimulation after TVR. Low chronic ST are resulting in an energy saving pacemaker mode. CV leads can be used after previous heart surgery as well as for difficult anatomical situations.

Electrocardiographic remodeling in patients paced for heart failure.

Congestive heart failure due to advanced coronary artery disease or dilated cardiomyopathy is often associated with intraventricular conduction delays. Electrical resynchronization is an evolving method to improve clinical and functional status. To evaluate whether pacing-induced changes in the electrocardiogram are related to hemodynamic changes, we analyzed electrocardiograms of patients enrolled in the Pacing Therapies in Congestive Heart Failure trial. The study population consisted of 42 patients, New York Heart Association functional class III-IV with a baseline QRS complex of 175 +/- 32 msec and a PR interval of 196 +/- 33 msec. The mean left ventricular ejection fraction was 0.23. Using high-resolution computer scans, we measured QRS duration of intrinsic and paced electrocardiographs at different times during the study. Results of the electrocardiographic measurements were correlated with functional results. During the crossover period, 34 episodes of biventricular pacing, 27 episodes of left ventricular pacing, and 5 episodes of right ventricular pacing occurred, each at an individual optimized atrioventricular (AV) delay. The only significant difference was that right ventricular pacing increased the QRS width by 40 msec as compared with baseline or biventricular pacing. Functional benefit, as indicated by relative increase of peak oxygen uptake (VO2) compared with baseline, was significantly correlated with shortening of paced QRS width (correlation coefficient, r = 0.55; p <0.05). After 12-month follow-up of 28 patients, we saw a slight, nonsignificant decrease of intrinsic QRS width. With regard to the underlying disease, intrinsic QRS width at baseline and at 12 months was also not significantly different between patients with coronary artery disease and dilated cardiomyopathy. This study found that right ventricular pacing causes an increase in QRS duration in patients with left bundle-branch block, whereas in left ventricular and biventricular pacing, QRS width remains unchanged. Shortening of QRS width is correlated with a pronounced relative increase of peak VO2, and thus may become a noninvasive marker of clinical efficacy. There is no evidence of remodeling of the intrinsic electrocardiogram after 12 months of pacing.

Delayed brachial plexus paralysis due to subclavian pseudoaneurysm after clavicular fracture.

Injuries to the brachial plexus and subclavian artery are serious complications of shoulder girdle trauma. Due to the close anatomical relationship between the brachial plexus and the subclavian artery in the thoracic outlet, both structures are often simultaneously involved in shoulder girdle injuries. Isolated lesions of the subclavian artery or the brachial plexus can also occur, especially with clavicular fractures. When a false subclavian aneurysm leads to a gradually increasing compression of the brachial plexus, the neurological signs and symptoms develop insidiously after the traumatic event.