[Catheter ablation--the first choice method in the therapy of artial flutter].
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Atrial Flutter↗
Biomedical subjects
J Kautzner
Publications and source records attributed to J Kautzner.
[Catheter ablation of ventricular tachycardia in patients with structural heart disease].
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Cardiomyopathies↗
Coincidence of idiopathic ventricular outflow tract tachycardia and atrioventricular nodal reentrant tachycardia.
BACKGROUND: Tachycardia-induced tachycardia appears to be a relatively rare condition. In such cases an important question arises whether catheter ablation of one arrhythmia may prevent the occurrence of another. This paper reviews single-centre experience with coincident idiopathic outflow tract ventricular tachycardia (VT) and atrioventricular (AV) nodal reentry tachycardia (AVNRT), and strategy of treatment. METHODS AND RESULTS: Seven of 46 patients (15%) with clinically documented idiopathic outflow tract VT were found to have reproducibly inducible AVNRT at the time of an electrophysiological study. There were two men and five women (mean age 35+/-9 years, range 20-44) without structural heart disease. During the study, AVNRT spontaneously triggered VT in three cases. Radiofrequency catheter ablation of the slow pathway did not suppress subsequent inducibility of VT in any of them. Successful catheter ablation of VT did not prevent clinical recurrence of AVNRT in one patient, and led to transition of VT into typical AVNRT in another. CONCLUSION: Coincidence of idiopathic outflow tract VT and AVNRT was found in 15% of cases of clinically documented idiopathic VT. Catheter ablation of one arrhythmia substrate did not prevent inducibility or clinical recurrence of the other. These data support the strategy of performing catheter ablation of both arrhythmia substrates during one session.
Adult↗
[Biventricular cardiac pacing].
Chronic heart failure (CHF) is a very frequent condition. Its frequency increases with prolongation of median life expectancy and due to improvements in medical care. However, medical treatment does not allow adequate control of symptoms in many cases. Therefore, various nonpharmacological approaches are being developed. The so-called biventricular pacing is one of them. Its main goal is to restore impaired mechanical cardiac synchrony that is present in patients with prolonged QRS duration due to inter- or intraventricular conduction abnormality. At present, biventricular pacing can be achieved through positioning of a special pacing lead into a branch of the coronary sinus on the surface of the left ventricle and implanting the other lead into the right ventricular cavity, and the third lead into right atrial appendage. Clinical trials and experience from many centres have documented improvements in clinical status in the vast majority of patients. An improvement in functional classification (NYHA) by at least one class, prolongation of the six minute walk distance by 20-40%, increase the maximal oxygen uptake by 10-40% a beneficial effect on quality of life can be expected. Preliminary results of the COMPANION trial have suggested that cardiac resynchronization therapy is associated with prognostic effect, especially in conjunction with implantable cardioverter-defibrillator.
Cardiac Output, Low↗
[The QT interval and its dispersion: what is its role in clinical practice?].
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Electrocardiography↗
[ECG in the diagnosis of supraventricular tachyarrhythmias].
The development of catheter ablation techniques during the last decade provided new data about the mechanism of supraventricular tachyarrhythmias and at the same time, set new requirements for their classification. An accurate diagnosis of individual SVT can usually be made during an electrophysiologic study that precedes catheter ablation. Nevertheless, clinically acceptable differential diagnosis of SVT can be based on analysis of a standard 12-lead electrocardiogram. This may prove useful especially when selecting optimum antiarrhythmic drug according to a suspected mechanism of arrhythmia. At the same time, electrocardiogram during SVT serves as a recording of clinical arrhythmia for catheter ablation. At present, SVTs are divided into 3 main categories: 1. atrial tachyarrhythmias confined solely to atrial tissue, 2. tachycardias involving the AV junction, and 3. AV reentrant tachycardias involving one or more accessory connections with an electric impulse travelling between atria and ventricles. The first category can be further subdivided into: a) macroreentrant atrial tachycardias related to the presence of macroscopic anatomical or functional barriers; b) focal atrial tachycardias arising from a focus of abnormal automaticity or microreentry in the atrium; c) the syndrome of inappropriate sinus tachycardia resulting most probably from hypersensitivity to adrenergic stimulation; d) atrial fibrillation based on the existence of multiple wandering wavelets in the atria. Electrocardiographic differential diagnosis is predominantly based on an analysis of the standard 12-lead ECG. Principal diagnostic features include the presence and timing of the P waves in relation to the QRS complex. Additional criteria comprise the presence or absence of AV block during the tachycardia, an axis orientation of the P waves and their morphology, the appearance of QRS alternans or frequency of tachycardia.
Catheter Ablation↗
Impact of electrocardiogram recording format on QT interval measurement and QT dispersion assessment.
The aim of this study was to determine the effect of recording conditions on the operator dependent measures of QT dispersion in patients with known and/or suspected repolarization abnormalities. Among several methods for risk stratification, QT dispersion has been suggested as a simple estimate of repolarization abnormalities. In a cohort of high and low risk patients, different components of the repolarization process were assessed in the 12-lead ECG using three different paper speeds and amplifier gains. To assess measurement error and reproducibility, a straight line was repeatedly measured. The operator error was 0.675 +/- 0.02 mm and the repeatability of the measurement error was 31 +/- 6%. The QT interval was most frequently measurable in V2-V5. Depending on the lead selected for analysis, the incidence of visible U waves was greatest in the precordial leads with high amplifier gain and low paper speed, strongly affecting QT interval measurement. The timing of the onset of the QRS complex (QRS onset dispersion) or offset of the T wave was strongly dependent on the paper speed. Paper speed, but not amplifier gain, had a significant shortening effect on the measurement of the maximum QT interval. As QT interval measurement in each ECG lead incorporates QRS onset and T wave offset (depending on the number of visible U waves), the dispersion of each of these parameters significantly affected QT dispersion. Thus, QT dispersion appears to reflect merely the presence of more complex repolarization patterns in patients at risk of arrhythmias.
Adult↗
Recurrent pericardial chest pain: a case of late right ventricular perforation after implantation of a transvenous active-fixation ICD lead.
A 36-year-old woman with a history of recurrent syncopal episodes presumably due to ventricular tachyarrhythmia in mitral valve prolapse underwent implantation of a transvenous ICD system. During a 23-month follow-up, she developed recurrent pericardial chest pain with pericardial friction rub. The first episode of chest pain occurred without any detectable change in pacing or sensing parameters. The second episode was associated with an increase in pacing threshold and drop in intracardiac signal amplitude. Right ventricular perforation was suspected fluoroscopically and confirmed by right ventriculography. This case report emphasizes the key steps in the diagnosis of this rare complication of an ICD implantation.
Adult↗
Radiofrequency catheter ablation of postinfarction ventricular tachycardia from the proximal coronary sinus.
Optimum strategy for radiofrequency (RF) catheter ablation of ventricular tachycardia (VT) after inferior wall myocardial infarction (MI) that originates from the posteroseptal process of the left ventricle is not known. We describe a case report of a 57-year-old man who developed recurrent post-MI VT with ECG morphology consistent with this type of VT (i.e., left bundle branch block pattern with predominant R waves from V2 to V6 and left-axis deviation). Endocardial mapping and entrainment during VT demonstrated a critical isthmus of the reentrant circuit in the proximal coronary sinus. RF application terminated VT and rendered it noninducible.
Bundle-Branch Block↗
[Clinical spectrum of ventricular tachycardias].
Substantial information has been accumulated concerning the mechanisms, electrocardiographic patterns and electrophysiologic characteristics of various ventricular tachycardias. As a result, several distinct clinical entities of ventricular tachycardia can be identified, each of them with different manifestation, prognostic importance and management strategies. Among monomorphic tachycardias, the sustained ventricular tachycardia after myocardial infarction is the most frequent form, accounting for more than 70% of all ventricular tachycardias. Monomorphic ventricular tachycardias are less frequently associated with dilated or hypertrophic cardiomyopathy, arrhythmogenic right ventricular dysplasia and other diseases. Distinct entity that should not go unrecognised is the bundle branch re-entry and/or interfascicular re-entry. Finally, there is a heterogeneous groups of idiopathic ventricular tachycardias occurring in patients without hay structural heart disease. Polymorphic ventricular tachycardias are often associated with either congenital or acquired QT interval prolongation, the so called torsade de pointes arrhythmias. In addition, some polymorphic ventricular tachycardias without QT interval prolongation may be triggered by ischaemia and/or can occur in patients with previous myocardial infarction. The review describes all the most important varieties of monomorphic and polymorphic ventricular tachycardias together with the treatment options.
Electrocardiography↗
Stability of the noninvasive baroreflex sensitivity assessment using cross-spectral analysis of heart rate and arterial blood pressure variabilities.
BACKGROUND: Depressed baroreflex sensitivity (BRS), usually estimated using the invasive phenylephrine method or the nitroprusside test, is significantly and independently associated with an increased risk of malignant ventricular arrhythmias and sudden cardiac death in patients surviving acute myocardial infarction. Several investigators have compared the standard phenylephrine test and different noninvasive methods. HYPOTHESIS: This study evaluated the influence of different body positions with different breathing regimes on cross-spectral baroreflex indices (coherence between the spectral densities of blood pressure and cardiac cycle variabilities) in both low- and high-frequency bands. METHODS: The data were obtained in 103 patients (73 males, aged 53 +/- 12 years) with coronary artery disease and/or hypertension. Simultaneous electrocardiographic and noninvasive blood pressure recordings were obtained in each subject in both supine and sitting positions during both spontaneous and slow and fast controlled respiration (0.1 and 0.33 Hz). RESULTS: The results show a significant bias and disagreement between noninvasive baroreflex sensitivity (BRS) indices. The mean values of the baroreflex in low frequency ranged from 5.0 +/- 5.3 to 10.1 +/- 7.9 ms/mmHg, while in high frequency, the mean values ranged from 6.6 +/- 6.1 to 10.1 +/- 7.9 ms/mmHg. The limits of agreement ranged from +/-1.7 to +/-4.1 ms/mmHg with bias from -1.0 to +0.7 ms/mmHg. CONCLUSION: A comprehensive comparison of different methods shows that BRS estimated in low-frequency band in sitting position during spontaneous respiration is the most representative part of the global baroreflex gain.
Adult↗
Cross-spectral analysis of heart rate and blood pressure modulations.
The cross-spectral analysis of heart rate (HR) and blood pressure (BP) variabilities provides "amplitude" and "phase" related measures. Compared to the amplitude measure, that is the baroreflex gain, the phase related measure characterizing the time lag between HR and BP oscillations has been studied to a much lesser extent. A population of 103 patients (73 men, 30 women, aged 53 +/- 12, range 20-82 years) referred for the management of coronary artery disease and/or hypertension were studied. In each subject, electrocardiogram and BP recordings were obtained in the supine and sitting positions of 5 minutes of rest (spontaneous respiration), 3 minutes of controlled respiration at 0.1 Hz (slow-controlled respiration), and 3 minutes of controlled respiration at 0.33 Hz (fast-controlled respiration). The frequency of maximum coherence (above the arbitrary threshold of 0.5) of BP and RR interval variabilities was searched between 0.033-0.133 Hz and 0.200-0.400 Hz to obtain baroreflex gain and phase shift in low and high frequency bands, respectively. Mean phase shifts of -79.1 and -67.0 degrees (-2.4 and -2.1 s) were found during slow-controlled respiration in the supine and sitting body positions, respectively. The mean phase shift between systolic BP and RR interval in the low frequency band was found between 83 and -109 degrees for body positions and respiration regimes. The actual baroreflex related time lag between systolic BP and RR variations was found between 3.5 and 5.1 seconds. The study concludes that the appropriate, and not always easy, selection of the frequency of maximum coherence between BP and HR oscillation is crucial for an accurate cross-spectral assessment of baroreflex sensitivity.
Adult↗
Utility of short-term heart rate variability for prediction of sudden cardiac death after acute myocardial infarction.
Heart rate variability (HRV) computed from 24-hour ECG recording has been associated with an increased risk of malignant arrhythmias after MI. To make HRV analysis more practical, we evaluated prospectively prognostic role of short-term HRV in comparison with other risk stratifiers. Study population consisted of 48 patients with acute MI (mean age 59.6 +/- 10.6 years, 38 males), who were off betablockers. All patients underwent 30-minute ECG recording at supine rest on day 2 and 5 after admission, between 9 and 11 a.m. One ECG channel from a commercial bedside monitor was A/D converted, and subsequently analysed using a purpose-built interactive software. Short-term HRV was computed as the standard deviation of all normal-to-normal RR intervals (SDNN) as well as the square root of the mean of the sum of the squares of differences between adjacent normal RR intervals (rMSSD). Left ventricular ejection fraction (LVEF, in %) was determined using 2D-echocardiography. During one-year follow up, 5 patients (10.4%) died of sudden cardiac death (SCD) and one of non-cardiac death. Subjects who died of SCD presented with significantly lower SDNN parameter on day 5 (28.8 +/- 4.3 vs 39 +/- 18.4, p < 0.006) and similar trend was revealed for rMSSD (12.22.8 vs 24.321, N.S.). Similarly, LVEF was significantly decreased in these patients (35.4 +/- 5.5 vs 49.7 +/- 11.3, p < 0.007). Positive predictive accuracy for prediction of SCD was 17% for rMSSD, 20% for SDNN, 29% for LVEF, and 40% for combination of depressed SDNN (< or = 33 ms) and LVEF (< or = 40). In conclusion, depressed HRV computed from short-term predischarge ECG recordings obtained under standardised conditions is associated with an increased risk of SCD. Such predictive power is substantially increased in combination with depressed LVEF, and this approach seems to be effective as a simple screening method to identify high risk subjects.
Arrhythmias, Cardiac↗
The effects of reflex parasympathetic stimulation on the QT interval and QT dispersion.
The effect of phenylephrine-induced reflex parasympathetic stimulation on QT interval and its dispersion was studied in 16 healthy subjects with a history of paroxysmal supraventricular tachycardia, both during sinus rhythm and during atrial pacing. Results demonstrate that rapid reflex parasympathetic stimulation does not influence QT interval duration or QT dispersion, and also emphasize the inappropriateness of Bazett's formula, the need for comparison of QT intervals during identical heart rates, and the importance of analyzing all 12 leads of a standard electrocardiogram when assessing the effects of various interventions on the QT interval.
Adult↗
Clinical relevance of heart rate variability.
Heart rate variability (HRV) has recently become a popular noninvasive research tool in cardiology. Clinical assessment of HRV is frequently based on standard long-term ambulatory electrocardiograms, whereas physiologic studies employ spectral analysis of short-term recordings under controlled conditions. From a general point of view, HRV can be used in clinical practice to estimate (1) the integrity of cardiac autonomic innervation, (2) the physiologic status of cardiac autonomic activity, and (3) the vulnerability to various cardiac arrhythmias resulting from autonomic imbalance. Clinical relevance of HRV has been clearly demonstrated in only two clinical conditions: (1) impaired HRV can be used alone or in a combination with other factors to predict risk of arrhythmic events after acute myocardial infarction, and (2) decrease in HRV is a useful clinical marker for evolving diabetic neuropathy. Substantial advances of our knowledge are required to establish and promote clinical applications in other areas of clinical medicine. To accomplish this task, proper hypotheses should be studied and appropriate techniques selected.
Autonomic Nervous System↗
Heart rate-independent prolongation of QTc interval in women with syndrome X.
BACKGROUND: Cardiac syndrome X is usually diagnosed in the presence of typical exertional chest pain, a positive response to exercise testing, and normal coronary angiograms. The underlying pathogenic mechanisms are speculative, but myocardial ischemia and increased sympathetic activity have been implicated. HYPOTHESIS: The present study examined whether QTc interval is prolonged in women with syndrome X when confounding factors such as heart rate, gender, and environmental conditions are accounted for. METHODS: Maximum QTc interval and its relationship to clinical and exercise variables were evaluated in 32 women with syndrome X (exertional chest pain, positive exercise testing, and completely normal coronary arteries) and 34 normal controls. RESULTS: Patients with syndrome X had significantly longer QTc interval (440 +/- 24 ms) than normal subjects (410 +/- 26 ms, p < 0.004). However, this QTc prolongation appears to be heart rate-independent as patients with syndrome X showed longer QT and QTc intervals than controls despite an identical heart rate. No relation was found between QTc prolongation and clinical or exercise test variables in patients with syndrome X. CONCLUSION: Although increased sympathetic drive is present in syndrome X, and this variable is likely to modulate QTc duration, the mechanism and clinical implications of QTc interval prolongation in syndrome X remain speculative.
Case-Control Studies↗
Effects of upright posture on filtered QRS parameter of the signal-averaged electrocardiogram in healthy volunteers.
The effects of upright posture on signal-averaged electrocardiography were studied together with short-term spectral analysis of heart rate variability (HRV) in 20 healthy volunteers (mean age 34 +/- 10 years). Filtered QRS duration from 5-minute epochs and corresponding spectral measures of HRV were computed from digital ambulatory electrocardiographic recordings both at supine rest and during upright tilt (60 degrees). Upright tilt was associated with a significant shortening of filtered QRS (88.2 +/- 8 vs 82.6 +/- 8 msec, p < 0.0001) and with an increase in its maximum amplitude (78.8 +/- 39 vs 87 +/- 48 microV, p < 0.004), whereas the average noise level remained unchanged. In the same time the ratio between low- and high-frequency components of HRV shifted in favor of sympathetic predominance (1.4 +/- 1.2 vs 3.4 +/- 2.9, p < 0.003). No correlation was found between changes in signal-averaged electrocardiography and HRV parameters associated with upright tilt. These data suggest that upright tilt-induced shortening in filtered QRS duration is rather vector-related and does not reflect changes in cardiac autonomic tone. This result must be considered when dynamic analysis of signal-averaged electrocardiography is attempted.
Adult↗
Sympathetic predominance of cardiac autonomic regulation in patients with left free wall accessory pathway and orthodromic atrioventricular reentrant tachycardia.
AIMS: The aim of this study was to compare cardiac autonomic regulation in patients with a history of paroxysmal supraventricular tachyarrhythmias, such as atrioventricular nodal reentrant tachycardia and atrioventricular reentrant tachycardia, and healthy controls. METHODS AND RESULTS: Seventeen patients with paroxysmal atrioventricular nodal reentrant tachycardia (atrioventricular nodal reentrant tachycardia group), 14 patients with overt preexcitation and paroxysmal atrioventricular reentrant tachycardia caused by a left free wall accessory pathway (atrioventricular reentrant tachycardia group) and 14 healthy control subjects, were studied. The patients and the controls were age and gender matched. Cardiac autonomic regulation was assessed by means of frequency domain analysis of heart rate variability at rest, during head-up tilt, active standing, treadmill exercise and after exercise. The high frequency component (0.15-0.5 Hz) of heart rate variability tended to be lower and the low frequency component (0.04-0.15 Hz) tended to be higher among the atrioventricular reentrant tachycardia patients than in atrioventricular nodal reentrant tachycardia patients and controls. The difference reached statistical significance at rest (P < 0.05) and during standing (P < 0.05 atrioventricular reentrant tachycardia vs atrioventricular nodal reentrant tachycardia and P < 0.01 atrioventricular reentrant tachycardia vs controls). Accordingly, the low-to-high frequency ratio--the marker of cardiac sympathetic regulation--was higher in atrioventricular reentrant tachycardia patients than in atrioventricular nodal reentrant tachycardia patients (P < 0.05 at rest and during standing) and controls (P < 0.01 during standing). CONCLUSION: The cardiac autonomic status in atrioventricular reentrant tachycardia patients was suggestive of a higher sympathetic tone than in atrioventricular nodal reentrant tachycardia patients or healthy controls. This may be related to inhomogeneous ventricular activation in the presence of antegrade conduction via the accessory atrioventricular pathway.
Adult↗