[Evaluation of efficacy and mechanism of action of angioplasty and directed atherectomy assisted by intravascular ultrasonography]. / Ocena skutecznosci i mechanizmów dzialania angioplastyki oraz aterektomii kierunkowej za pomoca ultrasonografii wewnatrznaczyniowej.

Intravascular ultrasound (IVUS) is a unique method of coronary lumen visualization enabling also examination the structure of the artery wall. Aim of this study was to assess efficacy and mechanisms of action of balloon angioplasty (PTCA) and directional atherectomy by means of IVUS. IVUS examination was performed before and after mechanical revascularization procedure in 37 pts (DCA-19 pts, PTCA-18 pts). Both PTCA and DCA resulted in enlargement of the coronary artery lumen (2.29 +/- 1.19 mm2 vs 2.93 +/- 1.55 mm2) but, also external diameter of the vessel increased after the procedure (1.94 +/- 1.10 mm2 and 0.74 +/- 1.01 mm2 retrospectively). In 55.6% of cases after PTCA plaque rupture or artery wall dissection was observed, mainly in eccentric lesions (70%). IVUS allowed to recognize details of artery lumen and define efficiency of procedure. In about 15% cases decision to continue PTCA or DCA was made on the basis of IVUS images only. The mechanism in which PTCA modifies the artery lumen is diverse and depends on the structure of lesion. Factors possibly responsible for enlargement of the lumen are: stretching, squeezing and translocation of atheroma as well as cracking and dissections along the arterial wall. DCA effectiveness depends on the withdraw of the atheromatous deposit, however, in over one-half of cases also stretching has some effect.

[Left ventricular stroke volume in individuals with dual chamber pacemaker (DDD). Effect of atrioventricular delay]. / Objetosc wyrzutowa lewej komory serca u osob z wszczepionym stymulatorem typu DDD. Wplyw czasu opóznienia przesionkowo-komorowego.

UNLABELLED: Programming of atrioventricular delay in patients with dual chamber pacemaker is very important for left ventricular filling and has a consequence for its stroke volume. The aim of this study was to evaluate the influence of atrioventricular delay for left ventricular stroke volume during pacing at two different rates. The study was performed in 36 patients with DDD pacemaker aged from 30 to 81 years, mean 56.1 +/- 14.6. Using Doppler echocardiography we have assessed left ventricular stroke volume during two pacing rates (70 and 100 ppm) with four atrioventricular delays (100, 150, 200 and 250 ms). We have found statistically significant difference between stroke volume with various atrioventricular delays. During pacing rate of 70 ppm the maximal difference was 19% and 15% during 100 ppm. Comparing both pacing rates the distributions of hemodynamically optimal atrioventricular delays was also significantly different. The best atrioventricular delay from the hemodynamic point of view was 36 ms longer during 70 ppm of pacing rate than during 100 ppm (p = 0.0009). The most often optimal delay at 70 ppm was 190-200 ms, and the rarest optimal delay was 90-100 ms; during 100 ppm pacing respectively: 140-150 ms and 240-250 ms. We have observed considerable personal variability in the hemodynamic response for atrioventricular delay changing as well as in the hemodynamically optimal values of this parameter during both pacing rates. CONCLUSIONS: 1. Atrioventricular delay programming has significant influence on left ventricular stroke volume. 2. Programming of atrioventricular delay should be performed individually in every patient because of personal variability of optimal values of this parameter.(ABSTRACT TRUNCATED AT 250 WORDS)

[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.