Innovation in the diagnosis and treatment of cardiac arrhythmias.

The 11th International Dead Sea Symposium on Cardiac Arrhythmias and Device Therapy - the 20th Anniversary of the meeting - was held in Jerusalem, Israel on the 26-29 February 2012. The global meeting was conducted with the goal of providing a venue for a multidisciplinary approach to exchange knowledge in all areas related to arrhythmia care. In addition to presentations of original research and keynote lectures, special educational sessions were offered that included hands-on anatomy training and interesting case presentations. A series of innovations sessions included presentations by start-up companies and inventors, leveraging the venue's entrepreneurial environment.

Bolus injection of acetylcholine terminates atrial fibrillation in rats.

It is well established that a tonic increase in the availability of the atrial muscarinic K(+) channels, either by enhanced vagal tone or by steady infusion of a low-dose of cholinergic or adenosine receptor agonists, promotes the genesis of atrial fibrillation. Here, we aimed to test the hypothesis that bolus administration of a muscarinic receptor agonist would destabilize and terminate atrial arrhythmia by uniformly and transiently activating K(+) channels throughout the atria, and that if the agonist was rapidly hydrolysable, it would dissipate before the more tonic, pro-arrhythmic effects could take hold. The episodes of untreated atrial fibrillation, induced in anesthetized rats by programmed electrical stimulation via trans-esophageal bipolar catheter, lasted on average 8.6+/-2.2 min (n=32). Intravenous injection of a model hydrolysable muscarinic agonist, acetylcholine (0.2 mg/kg body weight), converted atrial fibrillation into sinus rhythm within 8.4+/-1.9 s (n=10, P<0.05). The termination of an atrial fibrillation episode was always accompanied by transient bradycardia; the sinus rhythm gradually accelerated and reached pre-atrial fibrillation values within 10-20 s of injection. In conclusion, our evidence indicates that bolus administration of rapidly hydrolysable muscarinic agonist could be an effective way to pharmacologically terminate atrial fibrillation and restore sinus rhythm.

"Benign" course and malignant clinical presentations of congenital long QT syndrome.

This report describes the "benign" clinical course of a congenital long QT syndrome (LQTS) simulated acute coronary event in an 85 year old woman who had a history of recurrent syncope accompanied by numerous severe traumatic events from childhood. Her daughter died suddenly. LQTS was diagnosed on the basis of characteristic ECG findings, including a permanently prolonged QT interval, typical dynamic T-wave changes, and runs of torsades de pointes. A permanent DDDR pacemaker was implanted. Eighteen months after implantation there have been no further complaints of dizziness or syncope.

Multiple-vein thrombosis and pulmonary embolism after pacemaker implantation treated by thrombolysis.

This report describes a patient who suffered multiple-vein thrombosis following permanent pacemaker implantation and developed a pulmonary embolism while on anticoagulation treatment, which was successfully treated by thrombolytic therapy.

Effect of modern pacing algorithms on generator longevity: a predictive analysis.

Pulse generator (PG) longevity is of major importance to the quality of care of pacemaker patients. A series of automatic algorithms affect PG longevity. This study investigated the individual and combined effects of three algorithms incorporated in the Medtronic Kappa 700 pacemaker series: Capture Management periodically measures the stimulation threshold and adjusts the PG output, Sinus Preference allows the sinus rate to prevail in a specified range below the sensor rate, and Search AV allows an extension of the AV interval if spontaneous conduction is observed. The effects of Capture Management, Sinus Preference, and Search AV on device longevity were studied in 21 consecutive patients treated in the VDD and DDDR modes. Patients were followed for 1 year. The data were analyzed using an equation provided by the manufacturer. Capture Management was activated in 20 patients. For 11 PGs at the basic settings, longevity was extended by 5.2%, whereas reprogrammed PGs had no gain. Sinus Preference was active in four DDDR patients, who gained 12.0 +/- 5.3%atrial sensing from it, with a resultant longevity gain of1.4 +/- 0.45 months(NS). Search AV was active in 19 patients and 8 responders gained 7.8 +/- 4.4 months PG longevity. The overall longevity in this study was 106.3 +/- 8.4 months with all features as programmed, whereas the longevity without Capture Management and Search AV algorithms would be 98.2 +/- 4.9 months, saving 8.1 +/- 5.8 months(range 0-18) of battery life. Thus, two algorithms: Capture Management and Search AV, have clinical relevance in the extension of PG longevity.

Determinants of geographic variations in pacemakers and implantable cardioverter defibrillators implantation rates.

Despite the established therapeutic efficacy of pacemakers (PMs) and implantable cardioverter defibrillators (ICDs), marked geographic and national variations in their implant rates have been documented. Tabulation of implant rates and identification of variation patterns are of only modest significance as many factors influence geographic variations. This study examined statistical data regarding implant rates and analyzed the determinants behind these variations. The results showed: (1) the implantation rate of PMs and ICDs depends heavily on national economic status and demographics. (2) Economic factors are an important determinant of implant rates, though high rates were observed in countries with modest economic resources and highly educated physicians and populations. (3) Evaluation of PM and ICD implant rates per million of an overall population, unless based on demography, can lead to significant inaccuracy when comparing different regions and countries. Adjustment of implant rates consistent with demographic parameters is required. (4) Evaluation of the implant rate as appropriate, greater or less than expected in a given country can be achieved by calculation of a "reference" implant rate, and then by its comparison with the actual implant rate. Questions remaining after this analysis are: (1) How do variations in PM and ICD implant rate relate to quality of life, morbidity, and survival? (2) Will overall patient outcomes benefit from a greater implant rate, and is a higher implant rate cost-effective? (3) Should each country attempt to reach a "reference" implant rate, independent of its approach to medicine and level of economic development? These questions can only be answered by prospective randomized trials that allow the development of recommendations based on national needs and resources.

Mexiletine related chronic defibrillation threshold elevation: case report and review of the literature.

Many antiarrhythmic drugs may produce a rise in defibrillation threshold. Mexiletine is a frequently used antiarrhythmic drug in patients with an implantable cardioverter defibrillator, usually thought of as producing no or minimal effects on the defibrillation threshold. The current case report presents a patient with an endocardial implantable cardioverter defibrillator being treated with mexiletine, which precluded the ability to defibrillate the patient.