Implantation and follow-up of ICD leads implanted in the right ventricular outflow tract.

Unipolar ICD electrodes are routinely implanted at the right ventricular apex (RVA). However, inappropriate pacing/sensing parameters and/or high DFT may limit the appropriateness of the lead's implantation at the RVA. This study examined the effects on DFT of ICD leads implanted in the RVOT, attached to the high interventricular septum as an alternate location. DFT, defibrillation impedance, and sensing and pacing characteristics were measured at the time of implantation in 28 consecutive patients. Group A consisted of 12 patients in whom the ICD implantation criteria in the RVA were not satisfied, and whose lead was placed in the RVOT. Group B consisted of 16 patients with ICD electrodes implanted at the RVA. Mean DFT in group A was 11 +/- 4 J (4.5-20 J) versus 12 +/- 6 J (4-20 J) in the group B (P = 0.58). Defibrillation impedance was 81 +/- 9 omega (69-92 omega) in group A versus 77 +/- 15 omega) (46-93 omega) in group B (P = 0.43). R wave amplitude, slew rate, pacing threshold, and pacing impedance were comparable in both groups. In the perioperative period, the electrode needed to be repositioned in two patients from group A. There was no further dislodgment of RVOT defibrillation leads or other lead related complications during a follow-up of 23 +/- 9 months. The placement of ICD leads in the RVOT is an alternative to the RVA position. However, active-fixation ICD leads should be considered to limit the risk of electrode dislodgment.

[Advantages and controversies regarding physiologic electrostimulation of the heart in sinus node disease]. / Korzysci i kontrowersje tzw. fizjologicznej elektrostymulacji serca w chorobie wezla zatokowego.

UNLABELLED: Pacing mode in sinus node disease (SND) is one of controversies in cardiac pacing. We evaluated atrial pacing mode (AAI) in SND patients (pts). Between 1985 and 1994 AAI pacemaker was inserted in 179 pts due to symptomatic SND of varied etiology. RESULTS: The majority of pts (91.6%) were free from syncopal episodes after AAI implantation, in 15 pts (8.4%) syncopes were occasionally observed due to disturbances in pacemaker function, AVB III degrees, vaso-vagal syndrome, orthostatic hypotonia or atherosclerotic insufficiency of the cerebral circulation. In 49 (51%) out of 96 pts with brady-tachy syndrome (BTS), episodes of supraventricular tachyarrhythmia were not observed after AAI insertion and in the majority of the remaining pts the frequency of the episodes decreased significantly. Chronic atrial fibrillation developed in 5 (5.2%) pts. In some of the pts the symptoms related to chronic heart failure decreased or disappeared. A reoperation was performed in 44 (24%) pts due to electrode dislocation or fracture, atrio-ventricular conduction disturbances, an increase in pacing threshold or due to local infections. During the follow-up period 13 (7.3%) pts died of reasons unrelated to cardiac pacing therapy. CONCLUSION: In the majority of SND pts AAI pacing mode prevents from syncopal episodes caused by sinus node disfunction. It decreases the symptoms of heart failure in SND pts and stabilizes the sinus rhythm in the majority of BTS pts. Complications accompanying AAI do not post a major threat for the pts and can be easily resolved. They should by no means discourage from AAI implantation in SND.

[Complications associated with use of atrial electrodes]. / Powiklania zwiazane z zastosowaniem elektrod przedsionkowych.

The higher complication rate with atrial than ventricular leads make the physiological mode of pacing less popular. The aim of this study was to assess the complications associated with atrial leads. Between July 1985 and December 1991 we inserted 174 atrial leads in 165 patients (pts) with sick sinus syndrome or/and a-v block (AAI and DDD system respectively). A variety of different types of unipolar leads have been used: passive fixation simple or J shaped with the porous tip of vitreus-carbon (n = 49) and platinum-iridium (n = 78) or polished tip of Elgiloy (n = 18), active fixation (n = 29). The leads were manufactured by Siemens-Elema, CPI, Biotronik, Medtronic and Vitatron. All leads have similar acute electrical characteristics. The mean follow-up period lasted 28 months (12-83) until June 1992. We observed the following complications: displacement of electrode tip in 16 pts (9.7%), the disturbances of sensing in 10 pts (6%), 3rd degree of a-v block in 6 pts (5.4%) of 111 pts with AAI pacing, the exit-block in 3 pts (1.8%), suppuration in 3 pts (1.8%) in pacemaker area, various in 1 pt (0.6%). Total complication rate, which required reoperation was 20.6%. Complications associated with atrial leads implantation are not dangerous, may be easily treated and should not limit the indication for physiological pacing.

Atrioventricular conduction disturbances in patients with sinoatrial node disease and atrial pacing.

In sinoatrial node disease (SND) atrial pacing may be limited by progression of AV block. The incidence of AV block after AAI systems implantation range, according to various authors, from 0% to 12%. The aim of this study was to examine the AV conduction disturbances that forced a change in the mode of pacing in patients with AAI pacemakers. The information was collected retrospectively from a cohort of 122 patients. The follow-up period ranged from 5 to 83 months (mean = 35). Among these patients there were 37 with sinus bradycardia and 85 with bradycardia-tachycardia syndrome. Their mean age was 63 years. Before AAI pacemaker insertion, all patients had normal AV conduction on 12-lead ECG, and all but five had a Wenckebach cycle length shorter than 500 msec. Seven out of these 122 patients (5.7%) developed symptomatic conduction disturbances (second-degree type I AV block in five, second degree type II AV block in one, and third-degree AV block in one), necessitating a change from AAI to another mode of pacing. We conclude that progression of AV block after atrial pacemaker implantation in patients with SND is infrequent and mild in the majority of cases. Intraventricular disturbances such as left anterior hemiblock represent contraindication to AAI pacing particularly in patients who may be in need of antiarrhythmic drugs.

[Our experience using continuous atrial stimulation in sick sinus syndrome]. / Doswiadczenie wlasne z zastosowaniem stalej stymulacji przedsionkowej w chorobie wezla zatokowego.

Temporary atrial pacing (AAI) was applied in 31 patients with sick sinus syndrome (S.S.S.), including 20 with tachycardia-bradycardia syndrome (t.b.s.). In all patients before pacemaker implantation atrioventricular conduction was estimated using rapid left atrial, transoseophegeal stimulation assuming Wenckebach's point over 120 imp./min to be a physiological one. In all cases, but one ventricular electrodes were implanted and connected with multiprogrammable pacemakers (MP). Follow-up time ranged from 3 to 38 months (mean 18,4). Electrode dislodgment was not observed. In 9 persons sensing disorders were observed but thanks to programming the pacemaker sensitivity they could be resolved almost in all of them. Second degree Mobitz type I a-v block occurred in 3 patients during a long-term follow-up. In one of them changing the pacing mode to VVI was necessary. In persons with tachycardia-bradycardia syndrome cardiac pacing together with pharmacologic therapy allowed to almost eliminate tachycardia attacks. Authors positively estimated AAI pacing mode.