Variations of heart rate variability parameters prior to the onset of ventricular tachyarrhythmia and sinus tachycardia in ICD patients. Results from the heart rate variability analysis with automated ICDs (HAWAI) registry.

The HAWAI registry evaluated the role of heart rate variability in predicting the occurrence of ventricular tachycardia and fibrillation (VT/VF) and sinus tachycardia in patients with an implantable cardioverter-defibrillator (45 patients with 155 RR recordings). A significant decrease of the mean value of all RR intervals (MeanNN) was observed in the period starting 20 and 40 min prior to VT/VF and sinus tachycardia, respectively. The standard deviation of RR intervals (SDNN) and the power at low frequency (LF) were the only parameters with significant changes prior to VT/VF. For sinus tachycardia, the root mean square of successive differences of all successive RR intervals (r-MSSD) and the power at low and high frequency (HF) decreased, whereas SDNN and the power at very low frequency increased. Comparison of RR recordings preceding VT/VF and sinus tachycardia revealed significant differences of the MeanNN, SDNN, r-MSSD, LF and HF. Based on a classification and regression tree analysis, MeanNN, SDNN and r-MSSD showed a sensitivity of 94.4% and a specificity of 50.6% as predictors of VT/VF. Our results suggest that the temporal changes in heart rate before an arrhythmic event can be used to predict the occurrence of VT/VF. These parameters may be used to optimize pacing therapies designed to prevent VT/VF recurrences as well as for improving device-based discriminators for VT/VF and sinus tachycardia.

Contribution to the V-V interval optimization in patients with cardiac resynchronization therapy.

The present study proposed procedure for predicting an optimal left and right ventricular pacing interval delay (V-V interval). In 16 patients (heart failure, left bundle branch block, biventricular pacing) two methods (A and B) identifying optimal V-V interval were tested. Method A: predicted optimal V-V interval A (POVV-A) = electromechanical delay of the segment paced by left ventricle lead minus electromechanical delay of the segment paced by right ventricle lead. Method B: predicted optimal V-V interval B (POVV-B) = difference in the onset of aortic and pulmonary flows. Both methods were validated using echocardiography and right-sided heart catheterization. Cardiac output during POVV-A (4.6 l.min(-1)) was significantly better than that during POVV-A minus 20 ms (4.3 l.min(-1), p<0.01) and POVV-A plus 20 ms (4.3 l.min(-1), p<0.01), and than that during POVV-B (4.4 l.min(-1), p<0.05). LV dP/dt during POVV-A (818 mm Hg.s(-1), exceeded that during POVV-A plus 20 ms (717 mm Hg.s(-1),, p<0.05) and POVV-A minus 20 ms (681 mm Hg.s(-1), p<0.05), and that during POVV-B (727 mm Hg.s(-1), p<0.01). The time difference in onsets of myocardial deformation of left ventricle segment paced by the left ventricle and right ventricle lead allows identifying the optimal V-V interval and improves left ventricle performance.

Cardiac resynchronization therapy. Midterm follow-up of 128 patients.

OBJECTIVE: Cardiac resynchronization therapy has been used in the treatment of advanced heart failure with inter- and intraventricular dyssynchrony for more than ten years. AIM OF THE STUDY: A retrospective study was conducted to assess midterm results of biventricular (BiV) pacing in cardiac resynchronization therapy. METHODS: 128 consecutive patients (age 61.0+/-9.6, 98 males), with heart failure NYHA class 2.9+/-0.4 (2.5-3.5), with LBBB, QRS> or =130 ms, with dilated cardiomyopathy--DCM (86), with coronary artery disease--CAD (36), with both these etiologies (4) and with valvular disease (2) had a BiV PM (82) or BiV ICD (46) implanted in 2000-2007. AV delay was optimized individually, using echocardiography. Before and 3 months after implantation, the following was established: NYHA class, LVEF (echocardiographically), maximum oxygen uptake (spiroergometrically), left ventricle diastolic diameter and mitral regurgitation. The average follow-up time was 25.8+/-20.8 months. Complications and 2-year survival (n=68) were also assessed. RESULTS: 1) After 3 months of BiV pacing, NYHA class improved from 2.9+/-0.4 to 2.4+/-0.6 (n=99, p<0.001), LVEF increased from 20.2+/-4.9 to 23.9+/-6.6 % (n=92, p<0.001). Left ventricle diastolic diameter decreased from 69.8+/-8 to 67.5+/-10.0 mm (n=88, p=0.001) and mitral regurgitation was reduced from 2.2+/-0.9 to 1.9+/-0.9 (n=87, p=0.001) and maximum oxygen uptake during spiroergometry increased from 14.5+/-2.7 to 15.5+/-2.6 ml/min/kg (n=52, p=0.005). 2) Coronary sinus lead reposition was done in 2.3 %, epicardial lead implantation in 4.7 %, atrial lead reposition in 2.3 %, and right ventricular lead reposition in 2.3 % of patients. Contralateral reimplantation due to inflammatory complications in 1.6 % of patients. 3) Heart transplantation was performed on 9 patients. 4) Two-year survival was recorded in 77.9 % of 68 followed patients (72.2 % in CAD, 79.6 % in DCM). CONCLUSION: In the retrospective study of patients with BiV pacing a decline in heart failure, an increase in cardiac pump efficiency, reverse remodelling of left ventricle and acceptable occurrence of complications were confirmed (Tab. 4, Fig. 7, Ref. 18). Full Text (Free, PDF) www.bmj.sk

[The electrocardiogram in patients with implanted cardiac pacemakers]. / Elektrokardiogram u pacientu s implantovaným kardiostimulátorem.

In the submitted review the authors present electrocardiographic record of patients with atrial, ventricular and dual-chamber pacemakers. They also describe specially ECG findings in complications of cardiostimulation. Recommended procedures in these situation: changing pacemaker programme or electric cardioversion or surgical solution--reimplantation of pacemaker generator and/or lead or implantation of second lead.

[Atrial-triggered and ventricular-inhibited ventricular VDD pacing with atrial and ventricular single catheter electrodes--the Phymos MPS pacemaker]. / Sínemi spoustená komorami inhibovaná stimulace komor VDD se sínovou a komorovou elektrodou na monokatetru--Phymos MPS.

Optimal treatment from the haemodynamic aspect in complete atrioventricular block is dual-chamber DDD pacing. It makes possible atrioventricular sequence and adaptability of the frequency of ventricular pacing to the load under the control of the sinoatrial node. DDD pacing calls, however, for an atrial and ventricular electrode on two leads. Italian authors developed in 1984 a pacemaker (PM) PHYMOS (MEDICO ITALIA) which makes possible atrial triggered ventricular VDD pacing by means of a single pass lead with a tripolar electrode. As the first ones in the post-communist countries the authors implanted to six patients a PM PHYMOS MPS. They confirmed that the advantages of the VDD system, as compared with DDD, are the use of a single pass lead. This makes the implantation quicker, simpler and safer and reduces the time of X-ray irradiation and the incidence of electrodes dislocations. Another advantage is the lower incidence of atrial fibrillation and probably also pacemaker mediated tachycardias. The disadvantages of the VDD system are that atrial stimulation is impossible and that the diameter of the single pass lead is somewhat larger. According to data in the literature and the so far small experience of the authors, when the indication is correct--atrioventricular block grade III or II with intact function of the sinoatrial node--the advantages of VDD pacing with a single pass lead, as compared with DDD pacing, predominate over disadvantages.

[Cardiac pacing therapy of late intermittent AV block after surgery for tetralogy of Fallot]. / Pozdní intermitentní kompletní A-V blokáda po operaci Fallotovy tetralogie lécená kardiostimulací.

Postoperative atrioventricular block may be the cause of early or late death unless diagnosed and treated in time. The authors describe the development of late intermittent complete intraventricular block in an 11-year-old girl with syncope nine years after radical correction of the tetralogy of Fallot. Incomplete trifascicular block was diagnosed by electrophysiological examination of the conduction system four years before the development of complete trifascicular block. With regard to the serious character of an intermittent block cardiac pacing therapy was used.

Tip surface changes in endocardial stimulation electrode, visualised by scanning electron microscopy.

The authors have been probably the first investigators who applied scanning electron microscopy to studies of the changes occurring in the surface of the metalic tip of an endocardial stimulating electrode. They found a lowered conductivity for secondary electron emission, and describe the surface changes in a platiniridium-tipped electrode which had been used for almost four years, in comparison with an unused electrode.