Combipolar Sensing in Dual Chamber Pacing: Is There Still a Need for Bipolar Leads in the Atrium?

Bipolar leads have been shown to provide superior sensing conditions compared to unipolar leads as bipolar sensing is less susceptible to interference. However, the mechanical long-term integrity and longevity of bipolar leads is inferior to that of unipolar leads. A prospective randomized, multicenter study was performed to investigate a new atrial detection configuration called combipolar sensing. This new sensing concept is designed for the use of conventional unipolar leads in the atrium and the ventricle. While the atrial stimulation is unipolar, atrial sensing is accomplished in a bipolar way using the ventricular lead tip as the indifferent electrode. A modified dual chamber pacemaker provided with this sensing concept was implanted in 26 patients. At predischarge and at the 1- and 3-month follow-ups no significant differences in atrial sensing thresholds and P wave amplitudes were found between the unipolar and the combipolar sensing configuration at rest or during provocation. Myopotential inhibition could be demonstrated in 22 patients during unipolar sensing at sensitivity settings as "low" as 2 mV. In contrast, during combipolar sensing it could only be demonstrated in one patient once and only at the highest atrial sensitivity of 0.5 mV. Combipolar atrial sensing is feasible under normal conditions and during provocation. Myopotential interference is negligible. Thus, combipolar sensing offers comparable atrial sensing to bipolar without the disadvantages of a bipolar lead.     

彩色多普勒超声心动图对房颤病人复律后左房收缩功能的观察

目的：对房颤病人电转复后左房收缩功能的观察。方法：应用彩色多普勒超声心动图对２０例房颤病人转复窦性心率者于复律后１小时，２４小时，２周，及４周分别测量二尖瓣口舒张期血流频谱的Ａ峰流速，判定房颤转复后心房收缩功能的恢复过程。结果：１５例病人二尖瓣血流频谱Ａ峰流速电转复后１小时０．３０±０．１０ｍ／ｓ增至第４周０．６２±０．１４ｍ／ｓ（Ｐ＜０．００１）；２例病人２４小时Ａ峰流速恢复正常且大于Ｅ峰流速；１例病人至转复后４周仍未出现Ａ峰。另２例病人转复后一周复颤，其中１例未出现Ａ峰，１例仅出现低小的Ａ峰，且不随时间变化。结论：房颤转复后左房机械功能出现“顿抑”，从而提供临床房颤转复后应给予适当的抗凝治疗。     

Cardiac arrhythmias in the critically ill

Arrhythmias are a common problem in the critically ill and they can have significant effects on patient outcome. They often require immediate and swift action and it is, therefore, essential that clinicians have a structured approach to the recognition and management of arrhythmias. Here, we provide a framework for the appropriate management of the more frequently encountered cardiac arrhythmias in critical care. We include the algorithms from the 2015 Resuscitation Council Guidelines for reference.     

Safety and efficacy of radiofrequency ablation of common atrial flutter in elderly patients: a single center prospective study

Little data is available concerning the invasive treatment of atrial flutter (AFL) in elderly patients. The purpose of this prospective study was to evaluate the risks, safety, and follow-up of radiofrequency (RF) catheter ablation of common AFL in patients >75 years old (n = 61) (Group I) compared to patients younger than 75 years (n = 187) (Group II). The study population consisted of 248 patients (81% men/19% women), 21 to 96 years old (mean 66.3 +/- 12 years) with AFL, referred for RF from June 1999 to June 2001. RF endpoint was the assessment of the bidirectional block. The cumulative risk of atrial fibrillation (AF) was analyzed by the Kaplan-Meier method and log-rank test. The mean follow-up was 12.4 +/- 9 months. No complication occurred. Group I (80.1 +/- 4.5 years) did not differ significantly from Group II (61 +/- 11 years) regarding: AF history before ablation (34.4% vs 39.8%), structural heart disease (54% vs 42%), LVEF (57%+/- 12% vs 58%+/- 12%), left atrial size (43.8 +/- 7 vs 42.5 +/- 7), cava-tricuspid isthmus dimension (40 +/- 10 vs 39 +/- 4 mm), bidirectional block (100% vs 96.2%), RF application (12.5 +/- 10 vs 13.5 +/- 12 minutes), AFL recurrence (3.3% vs 5.3%), antiarrhythmic agents at hospital discharge (34.4% vs 38.9%), mean follow-up (12 +/- 9 vs 13 +/- 9 months) and AF occurrence (29.5% vs 20.3%; P = 0.2). Of these, the incidence of AF in patients without prior history (n = 150) was 7 (18%) of 39 for Group I and 11 (10%) of 111 for Group II (P = 0.1) after follow-up. Catheter ablation of AFL in very elderly patients appears to be a reasonable approach regarding feasibility, effectiveness, and low procedural risk.     

Recipient to Donor Conduction of Atrial Tachycardia Following Orthotopic Heart Transplantation

We report a case of atrial tachycardia in a 60-year-old male 8 years postorthotopic heart transplantation. At electrophysiology study, the clinical rhythm was found to arise from the remnant of the recipient atrium and was successfully terminated by delivery of radiofrequencv energy. Surgical scars formed at the anastomosis of the recipient and donor atrium during the time of orthotopic heart transplantation are thought to electrically isolate the two areas. Although rarely recognized, dysrhythmias originating from the recipient atrial remnant may occur more often than previously thought.     

Reliability of an Automatic Sensing Test with Beat-to-Beat Display of the Signal Amplitude

In contrast to testing of the capture threshold, the reliability of sensing tests has been little studied. This study was performed to test the automatic sensing algorithm included in the Biotronik pacing systems. The automatic measurements made by the devices were compared with the direct manual measurements made of 271 atrial (72%) or ventricular (28%) electrograms recorded in ten patients. A high correlation(r = 0.995, P < 0.0001) was found between the two types of measurements. The use of this function should facilitate the verification of accurate sensing during the long-term follow-up of pacemaker patients, and offers a tool to analyze the variations in amplitude of intracardiac signals.     

Atrial paroxysmal tachycardia in dogs and its management with homeopathic Digitalis--two case reports

Homeopathic Digitalis 6c was evaluated in two clinical cases of atrial paroxysmal tachycardia in dogs. Tachycardias are common cardiac problems in dogs, and atrial paroxysmal tachycardia is a serious cardiac arrhythmia that may lead to syncope. Both adult dogs (Labrador and German Shepherd) were treated with Digitalis 6c, 4 drops orally four times daily for 7 days. Following treatment with Digitalis 6c heart rate stabilised and synchronized atrial and ventricular electrical activity was restored in 7 days.     

Evaluation of the Atrial Evoked Response for Capture Detection with High-Polarization Leads

AutoCapture™ based on the evoked response can be confounded by electrode polarization. In this study, polarization was measured in human subjects who had chronic atrial leads. The aim of the study was to determine whether electrode polarization can be measured using a time integral atrial evoked-response integral (AERI) of the negative portion of the atrial paced ER evoked-response signal and to determine whether high-polarization atrial leads unsuitable for AutoCapture™ can be identified a priori. Atrial intracardiac-electrogram (IEGM) signals from 39 patients with implanted pacemakers were recorded and analyzed. The signals were recorded during conventional atrial-threshold searches. A total of 221 atrial-capture thresholds were recorded, ranging from 0.25 to 2.75 V with a mean of 0.79 V. Each evoked response was evaluated using the AERI in a 36 ms window following the 0.4 ms atrial stimulus. The polarization was estimated as a linear function of stimulus voltage using the evoked-response signal integral of captured beats identified on the IEGM. The 221 threshold-search datasets were obtained using leads with eight different electrode materials. Polarization could be measured using AERI as a function of stimulus voltage. Furthermore, this polarization measure can be used to identify high-polarization leads, which are ill suited for the atrial AutoCapture™ algorithm.     

The World Survey of Cardiac Pacing and Implantable Cardioverter Defibrillators: calendar year 1997--Europe

The registry of the European Working Group on Cardiac Pacing (EWGCP) is based on the European Pacemaker Identification Card originally designed in July 1978. National registration centers collect the local data and send aggregated annual data to the EWGCP. For 1997, data were obtained from 2,887 hospitals in 20 European countries representing a population of 568 million. Across all participating countries, the median value for all implanted pacemakers was 378 per million population. For initial pacemaker implants, the median value was 290 per million population. Single chamber atrial pacing was important in Denmark, the Netherlands, Poland, Slovak Republic, Spain, and Sweden for the treatment of sick sinus syndrome. Dual chamber pacing accounted for < 50% of initial implants in only 5 of 14 countries for atrioventricular block, and in only 3 of 15 countries for sick sinus syndrome. In 7 of 15 countries, unipolar ventricular leads were used in > or = 50% of cases. In 6 of 14 countries, there was > 15% use of unipolar atrial leads. Nine of 13 countries frequently used atrial active-fixation leads. For the 1997 survey, ICD data were obtained from 16 countries. The total number of ICDs per million population was a median value of 14. Initial ICD implants per million population was 11. Only 3 of 16 countries implanted a total of 30 or more ICDs per million population. Pacing and ICD practices were dependent on the availability of medical and technical resources and influenced by economic constraints inherent in health care administration and insurance coverage patterns.