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Biomedical subjects

Josef Kautzner

Publications and source records attributed to Josef Kautzner.

28 records · Page 2Linked to original sources
PubMed2004

The spectrum of inter- and intraventricular conduction abnormalities in patients eligible for cardiac resynchronization therapy.

Although cardiac resynchronization therapy (CRT) has clearly demonstrated its clinical benefit in patients with congestive heart failure (CHF) and intraventricular conduction abnormalities, selection of eligible patients and/or optimal pacing site are still a matter of debate. The aim of the study was to analyze the spectrum of conduction abnormalities in CRT candidates. A total of 26 patients (mean age 62 +/- 9 years) with CHF and conduction disturbances (QRS > or = 130 ms) were studied. The underlying heart disease was dilated cardiomyopathy (DCM) (n = 12) or coronary artery disease (CAD) (n = 14). High density, left ventricular endocardial activation maps were constructed using an electroanatomic mapping system (CARTO). Based on endocardial activation patterns, left ventricular conduction abnormalities were classified as left bundle branch block (LBBB) (n = 9), nonspecific intraventricular conduction disturbances (n = 10), and the bifascicular block (n = 7). In DCM patients the endocardial activation sequences corresponded with a 12-lead ECG pattern with a homogeneous spread of activation wavefront and the latest activation laterally (LBBB) or anteriorly (bifascicular block), respectively. CAD patients presented with variable activation patterns that reflected the location of the postinfarct scar, and the 12-lead ECG was less predictive. Although there was a trend for longer QRS durations for DCM subjects (170 +/- 23 vs 156 +/- 23 ms, P = NS), left ventricular activation time was significantly longer in the CAD group (115 +/- 21 ms vs 134 +/- 23 ms, P < 0.05). CRT candidates represent a broad spectrum of conduction abnormality patterns with variable inter- and intraventricular activation delays. CAD subjects have more pronounced intraventricular conduction abnormality. The standard ECG is less reliable in the characterization of complex conduction abnormalities.

Adult↗
PubMed2003

Catheter ablation of ventricular tachycardia following myocardial infarction using three-dimensional electroanatomical mapping.

One challenge encountered during catheter ablation of postinfarction ventricular tachycardia (VT) is the inducibility of multiple VT morphologies associated with variable hemodynamic instability. The clinical usefulness and safety of a three-dimensional electroanatomical mapping in guiding radiofrequency (RF) catheter ablation of VT, used in parallel with a multichannel recording system, was studied in 28 men (mean age = 63.8 +/- 10.6 years, mean left ventricular ejection fraction = 28% +/- 9%). Three-dimensional voltage maps of the left ventricle were obtained in sinus rhythm with annotation of areas of fractionated or late potentials, zones of slow conduction and/or dense scar with no pacing capture at 10 mA. RF lesions were created either in sinus rhythm or during hemodynamically stable VT within reconstructed critical zones of the circuit. A total of 82 VTs were induced (mean = 2.9 +/- 1.0/patient). Hemodynamically unstable clinical VTs were induced in 5 patients, and clinical or nonclinical unstable VT in 14. Clinical VT was rendered noninducible in 24/28 (85.7%) patients, and monomorphic VT was eliminated in 16/28 (57.1%) patients. The mean procedural time was 258 +/- 82 minutes, and fluoroscopic exposure 13.5 +/- 8.8 minutes. During a mean follow-up period of 10.6 +/- 6.4 months, catheter ablation was repeated in 6 patients for VT recurrences. No significant complications occurred except for a transient cerebral ischemic attack in one patient. In conclusion, electroanatomical mapping assisted the successful and safe catheter ablation of both mappable and nonmappable VTs in a significant proportion of patients after myocardial infarction.

Catheter Ablation↗
PubMed2003

Clinical application of electroanatomical mapping in the characterization of "incisional" atrial tachycardias.

UNLABELLED: Scar tissue after surgical procedures for congenital heart disease may create a complex arrhythmogenic substrate and expose patients to the risk of "incisional" tachycardia. We report the usefulness of electroanatomical mapping in the characterization of reentrant circuits and identification of sites of successful radiofrequency (RF) ablation. METHODS: Electroanatomical mapping was used to draw activation maps of the right atrium in 6 men and 4 women (mean age 45 +/- 13.7 years) with 21 atrial tachycardias after corrections of atrial septal defects (n = 6) or tetralogy of Fallot (n = 4). The critical isthmus of reentrant circuits was ablated by RF energy. RESULTS: Macroreentrant circuits were localized on the posterolateral wall of the right atrium in all cases. Scar tissue in that region often contained several pathways that allowed induction of different tachycardias. Interruption of all slow conducting pathways successfully abolished all inducible tachycardias. The cavotricuspid isthmus participated in a figure-of-eight reentrant circuit or in a typical flutter circuit in 6 patients. RF ablation was successful in all but one patient, without significant complications. CONCLUSION: Electrocanatomical mapping allows the precise description of macroreentrant circuits and the identification of all slow conducting pathways. It is a powerful tool for the planning of ablation lines, navigation of ablation catheter, and verification of conduction block.

Adult↗
PubMed2003

Anatomic characteristics of extensions of atrial myocardium into the pulmonary veins in subjects with and without atrial fibrillation.

Myocardial extensions around pulmonary veins (PVs) have been recognized as the most important sites of origin for arrhythmogenic foci that trigger atrial fibrillation. The aim of this study was to evaluate the characteristics of atrial myocardium in pulmonary veins from subjects with and without a history of atrial fibrillation. A total number of 43 human hearts obtained at autopsy were studied (27 men, 16 women, mean age 67 +/- 8 years). Sixteen subjects (group 1) had a history of atrial fibrillation (11 men, mean age 66 +/- 10 years). The remaining 27 subjects (group 2) were without arrhythmia (16 men, mean age 68 +/- 8 years). The presence and morphology of the myocardial extensions were studied microscopically. Of the total number of 172 PVs evaluated, myocardial extensions were revealed in 117 (68%) cases. Myocardial fibers were arranged in a variable manner with the most prevailing circular pattern. Continuous extensions were present in 74, while a discontinuous pattern was revealed in 29 PVs. Maximum extension of the sleeves reached 48 mm (mean 7.7-10 mm) and their maximum thickness was 5 mm. Myocardial extensions were longer and thicker in the upper PVs from subjects with previous atrial fibrillation. In conclusion, a significant interindividual variability in the presence, arrangement, and thickness of atrial myocardial sleeves into PVs was revealed. Patients with a history of atrial fibrillation were found to have longer and thicker myocardial extensions into the upper PVs, and this finding may have implications for the catheter ablation technique.

Aged↗
PubMed2002

Mapping and ablation of idiopathic ventricular fibrillation.

BACKGROUND: Ventricular fibrillation is the main mechanism of sudden cardiac death. The feasibility of eliminating recurrent episodes by catheter ablation has not been reported. METHODS AND RESULTS: Twenty-seven patients without known heart disease (13 men, 14 women, 41+/-14 years of age) were studied after being resuscitated from recurrent (10+/-12) episodes of primary idiopathic ventricular fibrillation; 23 had received a defibrillator. The first initiating beat of ventricular fibrillation had an identical electrocardiographic morphology and coupling interval (297+/-41 ms) to preceding isolated premature beats typically noted in the aftermath of resuscitation. These triggers were localized by mapping the earliest electrical activity and ablated by local radiofrequency delivery. Outcome was assessed by Holter and defibrillator memory interrogation. Premature beats were elicited from the Purkinje conducting system in 23 patients: from the left ventricular septum in 10, from the anterior right ventricle in 9, and from both in 4. The interval from the Purkinje potential to the following myocardial activation varied from 10 to 150 ms during premature beat but was 11+/-5 ms during sinus rhythm, indicating location at peripheral Purkinje arborization. The premature beats originated from the right ventricular outflow tract muscle in 4 patients. The accuracy of mapping was confirmed by acute elimination of premature beats during local radiofrequency delivery. During a follow-up of 24+/-28 months, 24 patients (89%) had no recurrence of ventricular fibrillation without drug. CONCLUSIONS: Primary idiopathic ventricular fibrillation is a syndrome characterized by dominant triggers from the distal Purkinje system. These sources can be eliminated by focal energy delivery.

Adult↗
PubMed2002

Role of Purkinje conducting system in triggering of idiopathic ventricular fibrillation.

Ventricular fibrillation is the main mechanism of sudden cardiac death, but the source of its spontaneous initiation has not been mapped. 16 patients were investigated by electrography and radiofrequency ablation after resuscitation from recurrent idiopathic ventricular fibrillation. Triggers of ventricular fibrillation originated from various locations within the Purkinje system in 12 patients and from the ordinary myocardial muscle in four. The accuracy of mapping was confirmed by acute elimination of triggers by radiofrequency delivery, and there was no recurrence of ventricular fibrillation in 14 patients. Long-term follow-up is necessary to establish that ablation is curative and avoids use of a defibrillator.

Adolescent↗
PubMed2002

QT interval measurements.

The QT interval, which represents duration of ventricular electrical systole, i.e., the time required for completion of both ventricular depolarization and repolarization, has been a parameter of particular interest in cardiology. However, the relationship between duration of cellular action potentials and the QT interval recorded at the body surface is very complex. As a result, the QT interval is difficult to measure with precision. First, there is inherent imprecision in identifying the end of the T wave because of incomplete understanding of the recovery process and its projection on the body surface. Second, significant variation both in the onset of the QRS complex and the end of the T wave among some ECG leads provides different QT values depending on the leads selected for measurement. Third, technical factors such as paper speed and sensitivity influence QT measurements with higher paper speed leading to shorter interval values and higher sensitivity resulting in QT prolongation. The above problems do not appear to be solved by automatic QT measurement techniques, which have been found to be less accurate in cardiac patients than in healthy controls. In conclusion, we should accept that QT interval remains merely a gross measure of ventricular electrical systole and/or repolarization and we should not expect significant improvement in accuracy of traditional QT interval measurements. Rather, in clinical research, methods examining the shape or amplitude of the T wave and its changes related to heart rate should be exploited.

Arrhythmias, Cardiac↗
PubMedDate not supplied

Expression of Leu-7 in myocardial sleeves around human pulmonary veins.

BACKGROUND: Atrial fibrillation (AF) is the most common sustained clinical arrhythmia. Myocardial sleeves onto pulmonary veins (PVs) have been recognized as a frequent site of origin of focal triggers for this arrhythmia. Expression of Leu-7 has been hypothesized to correspond with abnormal atrial automaticity. OBJECTIVE: To evaluate a possible role of the Leu-7 immunoreactivity in AF patients, we studied Leu-7 expression in myocardial sleeves. METHODS: Leu-7 was studied immunohistochemically in paraffin-embedded specimens from 55 human autopsied hearts (mean age 69 years, range 42-94 years, 34 males, 21 females). Twenty-two of the subjects had previous history of AF. RESULTS: Myocardial sleeves were found in 151 out of a total number of 220 PVs (68.6%). Leu-7 granular cytoplasmatic positivity was observed in 15 (9.9%) PVs from 12 different hearts: 6 (15.4%) in the right superior, 4 (10.2%) in the right inferior, 4 (10.8%) in the left superior and 1 (2.7%) in the left inferior PV. This finding was revealed both in patients with and without the history of AF. CONCLUSIONS: Leu-7 positivity, hypothesized to correspond with abnormal atrial automaticity, can be detected in some myocardial sleeves around PVs. However, no statistical relationship to previous history of AF was found.

Adult↗