Roman Kępski

Ventricular fibrillation risk factors in over one thousand patients with accessory pathways

BACKGROUND Published data concerning risk factors of VF in WPW patients are inconsistent or contradictory. METHODS AND RESULTS We included 1007 patient (pts) (mean age 35 years; 45% female) with an accessory pathway (AP) referred for non pharmacological treatment. Group 1 consisted of 56 pts (42M, aged 34 ± 15 yrs) with an AP and documented VF and Group 2-951 pts (513M, aged 35 ± 15 yrs) with an AP and without VF. Univariate predictors of VF were: overt pre-excitation, male gender, multiple AP, large AP. Multivariate predictors were: overt pre-excitation, male gender and MAP. The mean shortest pre-excited RR interval during AF was significantly shorter in Group 1: 205 ± 27 vs. 243 ± 64, P=0.019. VF as an end point of the first arrhythmia episode (AVRT or AF) was observed in 20 pts (15M, 5F). Primary VF (no documented arrhythmia prior to aborted SCD) occurred in 16 pts (13M, 3F). The mean age of primary VF pts was significantly lower than of pts with history of AVRT or AVRT and/or AF (24.5 vs. 36.5 vs. 38 yrs., P<0.005 and P=0.002, respectively). Age at VF occurrence shows a bi-modal distribution with peak occurrences in the 2-nd/3-rd and 5-th decades. CONCLUSION In patients with an accessory pathway, overt pre-excitation, male gender and multiple AP constitute independent risk factors of VF episodes. Young patients in the 2-nd/3-rd and older patients in the 5-th decade might be at higher risk of VF occurrence.

Noninvasive Recording of His‐Purkinje System (HPS) Activity in Man on Beat‐To‐Beat Basis

Since 1969 His bundie electrography has been used for diagnosis and for the study of cardiac electrophysiology. This method has employed the catheterization technique and has allowed the continuous recording of electrical activity of the specialized cardiac conduction system in every beat. Such investigation, because of its invasive nature, cannot be considered a routine test; it requires expensive instrumentation, it has physiological and technical limitations that include discomfort, a slight morbidity risk and a rather limited recorded area within the heart. In 1973 a method was developed for a noninvasive recording of the electrical activity within the P‐R segment of the electrocardiogram measured from the body surface. This method which employs the signal averaging technique delivers even less medical information than intracardiac measurement. The shortcomings of this averaging method include inability to detect beat‐to‐beat changes in the true signal. Such a method is not useful in transient arrhythmia detection and a “short acting” drug influence examination. The technical approach to the beat‐to‐beat noninvasive recording of the HPS activation signal as measured from the body surface has been proposed. Using a specially positioned electrode system, a low noise multiple parallel input amplifier and a computer for sampling, processing and plotting of the measured signal, wehave obtained an output curve corresponding to the continuous beat‐to‐beat HPS activity. (PACE, Vol. 5, July‐August, 1982)

Adaptive filtering in exercise high resolution ECG as applied to the hypertrophic cardiomyopathy.

KEPSKI, R., et al.: Adaptive Filtering in Exercise High Resolution ECG as Applied to the Hypertrophic Cardiomyopathy. The application of adaptive filtering to ECG signals has been investigated for many years. This study shows that the exercise high resolution ECG (HRECG) can also be processed successfully in a similar way. Two groups were included consisting of 20 healthy individuals and 24 patients with hypertrophic cardiomyopathy (HCM) . The HRECG parameters for both groups were similar (QRSdur: 107 ± 7 vs 114 ± 18 ms NS, LAS: 25 ± 8 vs 22 ± 6 ms NS). In the first step, the HRECG signal was acquired at rest to obtain the averaged reference pattern. The next step was associated with peak exercise in which one could calculate short duration averaging (∼ 30 beats) or apply adaptive filtering in which the exercise component (EC) was extracted. Exercise was performed in the supine position on a bicycle ergometer. The load of 50 W was incremented by 50‐W steps in 3‐minute intervals and the test was ended by fatigue. Signals were recorded in X, Y, and Z bipolar leads with a 20‐Hz high pass filter. The short time average QRS duration mostly was abbreviated in normal individuals in contrast to HCM patients in which ventricular activity prolonged with sensitivity, specificity, and negative and positive predictive values: 79%, 65%, 73%, and 72%, respectively. The adaptive recurrent filtration (ARF) after cutoff of the EC at the level of 70 ms (this level is the EC mean value of both groups) showed the following statistics: 63%, 90%, 88%, and 90%. The Students t‐test as applied to the duration of EC allowed a statistically significant difference between normals and HCM patients (66 ± 4 vs 71 ± 6 ms, P < 0.0052) and between HCM patients with and without ventricular tachyarrhythmia and DS (74 ± 6 vs 69 ± 6 ms, P < 0.046).

Pyramid Electrode Location in a Cardiac Micropotential Study

There are several electrode systems dealing with low noise, body surface, and ECG recordings that have been suggested by various investigators. In the last few years, the most developed system for late potential detection has been related to the uncorrected Frank XYZ leads. However, for His bundle defection many different electrode networks have been used. A pyramid‐type electrode system has been used previously for His‐Purkinje signal measurement and, with some modifications, for late ventricular activity recordings. This pyramidtype system was used to evaluate 300 adult patients with coronary heart disease (CHD) or cardiomyopathy. In the proposed system, electrodes are located near the myocardium with their configuration consisting of three electrode pairs forming a pyramidal shape. Each electrode can also play the role of the top of the pyramid, with all measurement directions converging to a point. By changing the pyramidal top, signals can be defected in various chosen measurement directions. The pyramid system provides spatial averaging facility, allowing the whole measuring sysfem (consisting of low noise multi‐input amplifiers) to defect signals in fhe range of lμVp‐p on a beat‐to‐beat basis. In the majority of cases in hospital environments, however, a number of digital averaging cycles is still necessary. Using this system, late potentials (LP) were found in 29% of the patients without myocardial infarction (MI) and in 86% of cases with remote MI and sustained ventricular tachycardia (VT) and/or ventricular fibrillation (VF). Waveforms suspected to be of His‐Purkinje System (HPS) origin were detected in 71% of subjects with normal or prolonged P‐R segment.

P1-63 FIRST EPISODE OF ATRIAL FIBRILLATION IN OVERT AND CONCEALED WOLF-PARKINSON-WHITE SYNDROME

Background: Long refractory period of the A-V node is a natural barrier, which protects the ventricles from too fast heart rhythm. In WPW syndrome, AF is particularly dangerous when accessory pathway (AP) has short refractory period. The aim of our study was to analyze the occurrence of AF in dependence on sex, age, property of AP and other factors (CHD, HT) Methods: 747 pts, mean age 35.5, underwent non-pharmacological treatment of WPW (years 1988-2005). 221 (39.5%) of them (68 F, 153 M) had documented atrial fibrillation. The results of 12 lead ECG Holter, ECG monitoring, and an echocardiography study were analyzed. Results: 140 pts (63.3%) have had episode of AF and AVRT, 79 (25,5%) only AF. 20 pts (9%) have documented VF. 18% had HT, 7,3% CHD, 13,7% changes in coronary arteries, 8,7% valvular heart disease. 20% underwent cardioversion. Women had the first episode of AF most frequently at 4 decade (25.5%), men at 3rd (27.6%). The mean age of the first AF episode in men was significantly lower than women (32.4 vs 39.6). More frequently AF occured in pts with left sided AP (61%) than right-sided (30%). Midseptal occurs seldom (9%). AF occurred most frequently in overt APs – 81.3% (intermittent – 11%, and concealed – 7.7%). Conclusions: Men have had AF episodes 2,2 times more often than woman. Pts with avrt have had AF earlier than pts without avrt (36 vs 46). Men have had first episode of AF earlier than women (32.4 vs 39.6).

Adaptive filtering in dynamically changing high resolution ECG

An adaptive filtering system for the assessment of a dynamically changing exercise ECG signal is described. The system is composed of two time-sequenced recurrent filters working in parallel. At the output the differential signal component related to the exercise with improved signal to noise ratio is obtained. The system showed its clinical usefulness in the assessment of the patients with hypertrophic cardiomyopathy and revealed its superiority compared with the signal averaging process used as standard.