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Biomedical subjects

J Kautzner

Publications and source records attributed to J Kautzner.

At least 37 records · Page 2Linked to original sources
PubMed1997

QT interval dispersion and its clinical utility.

QT dispersion as a measure of interlead variations of QT interval duration in the surface 12-lead ECG is believed to reflect regional differences in repolarization heterogeneity and thus, may provide an indirect marker of arrhythmogenicity. Methodology for determining QT dispersion and reproducibility of this parameter vary significantly between studies and, together with some other unresolved problems with QT dispersion assessment, often lead to contradictory suggestions about potential clinical utility of this parameter. The results of our own study in 213 survivors of myocardial infarction, together with a comprehensive review of the literature, suggest that most of these inconsistencies reflect incomplete understanding of electrocardiographic correlates of both normal and abnormal ventricular repolarization. The application of more objective techniques, such as spectral analysis or combined assessment of different parameters (e.g., area beneath the T wave and its symmetricity) may add a new dimension to the noninvasive assessment of ventricular repolarization.

Arrhythmias, Cardiac↗
PubMed1997

Exercise-induced T-wave alternans as a marker of high risk in patients with hypertrophic cardiomyopathy.

Microvolt-level T-wave alternans (alternating morphology from beat to beat) during atrial pacing and exercise may predict ventricular tachycardia (VT) and fibrillation (VF) in ischemic heart disease. We tested whether such alternans during exercise could identify high-risk patients with hypertrophic cardiomyopathy (HCM). We studied 14 HCM patients and 9 normal control subjects for T-wave alternans u sing the CH2000 system with 7 multisegment electrodes in a Frank orthogonal (XYZ) configuration. Bicycle ergometer exercise was used to increase the heart rate (HR) to 95-110 beats/min. Seven patients were at high risk for ventricular arrhythmias (1 with sustained VT, 3 with abnormal paced ventricular electrograms as seen in VF survivors, and 3 with nonsustained VT and/or an adverse family history), and the other 7 were at low risk. T-wave alternans was present if alternans > 1.9 microV was consistently present with the HR in excess of a patient-specific HR threshold. Alternans was found in 5 of 7 high-risk patients (71%) vs none of 7 low-risk patients or 9 control subjects (p < 0.025 and p < 0.01, respectively). Notably, all 4 patients with sustained VT or abnormal ventricular electrograms showed alternans. Thus, high-risk patients with HCM often show T-wave alternans. Microvolt-level alternans during exercise may be a useful marker for ventricular arrhythmic risk in patients with HCM.

Adult↗
PubMed1996

Arterial baroreflex sensitivity assessed from phase IV of the Valsalva maneuver.

To assess the feasibility of 2 noninvasive methods for arterial baroreflex sensitivity testing based on phase IV of the Valsalva maneuver, the performance of a simple arterial baroreflex sensitivity index compared with a slope method and reproducibility of repeated measurements of either parameter were evaluated in 36 subjects without structural heart disease. The study showed feasibility and reproducibility of both these methods for arterial baroreflex sensitivity assessment and demonstrated the importance of an appropriate rest period between repeated Valsalva maneuvers, giving a basis for prospective testing of noninvasive determination of arterial baroreflex sensitivity together with phenylephrine method in survivors of myocardial infarction.

Adolescent↗
PubMed1996

Anomalous origin of the right coronary artery from the pulmonary trunk: is surgical reimplantation into the aorta a method of choice?

The origin of the right coronary artery (RCA) from the pulmonary trunk (PT) is a rare congenital anomaly. Although most of the patients remain asymptomatic, prophylactic reimplantation of the RCA into the aorta has been recommended to prevent an adverse outcome. The report describes postoperative results in two patients following uneventful RCA reimplantation. A 47-year-old man, with coexisting diffuse atherosclerotic involvement of the left coronary artery, remained symptomatic despite the establishment of a two-coronary system. The second patient, a 36-year-old woman, with isolated anomalous origin of the RCA from the PT, continued to present with myocardial ischemia on exertion. The original observation of an angiographic "slow-flow" phenomenon in the reimplanted RCA in both patients implies the impairment of myocardial microvessels. These findings give rise to the question of whether the reimplantation of the anomalous artery is really superior to simple ligation of its origin in order to relieve the "coronary steal" effect.

Adult↗
PubMed1996

Is vagal innervation to the atrioventricular node impaired after radiofrequency ablation of the slow atrioventricular nodal pathway?

To assess the potentially adverse effects of RF catheter ablation (RFCA) of the slow AV nodal pathway on the parasympathetic innervation to the AV node in patients with AV nodal reentrant tachycardia (AVNRT), AV nodal conduction was evaluated following vagal stimulation by means of a phenylephrine bolus injection (200 micrograms) before and after RFCA in ten patients (mean age, 37 +/- 14 years). Nine patients with AV reentrant tachycardia (AVRT) due to a left free wall accessory pathway served as a control group (mean age of 37 +/- 12 years). Whereas no prolongation of the AH interval was observed in the AVNRT group following the phenylephrine bolus during sinus rhythm, despite a significant slowing in sinus rate, phenylephrine administration in AVRT patients was associated with both slowing of the sinus rate and prolongation of the AH interval. Following successful RFCA, the same responses were observed. To delineate the indirect effect of heart rate on AV conduction in response to the phenylephrine bolus, the AH interval was also measured during fixed atrial pacing. A marked prolongation of the AH interval occurred in both groups following phenylephrine administration. This prolongation was biphasic in 50% of AVNRT patients before ablation, suggesting a predominant effect of vagal stimulation on the fast AV nodal pathway. RFCA was associated with disappearance of discontinuous AV conduction in all but one patient with AVNRT. Vagal stimulation caused the same amount of AH interval prolongation as before RFCA in both study groups. In conclusion, patients with AVNRT have a preserved modulation of AV nodal conduction in response to vagal stimulation during sinus rhythm. In addition, vagal stimulation seems to exert a predominant effect on the fast AV nodal pathway. RFCA of the slow AV nodal pathway in patients with AVNRT does not cause detectable damage to the vagal innervation to the AV node.

Adult↗
PubMed1996

Assessment of arrhythmias after myocardial infarction in the post-CAST era.

Prevention of sudden cardiac death after myocardial infarction (MI) has become a continuing challenge for clinical cardiology. Of the many treatment modalities available, some have been shown to save lives while others may even have deleterious effects. Further survival studies exploring the efficacy of prophylactic treatment will be necessary before conclusions for routine clinical practice can be drawn. For this purpose, improvements in the process of risk stratification must be made before these studies are able to demonstrate potential survival benefit. This article will review both the established and the new methods of risk stratification for the post MI patient, with particular attention to antiarrhythmic therapy.

Amiodarone↗
PubMed1995

Day-to-day reproducibility of time-domain measures of heart rate variability in survivors of acute myocardial infarction.

We conclude that in clinically unchanged conditions, the time-domain HR variability measures derived from 24-hour ambulatory recordings of AMI survivors are stable during the early convalescent phase, and the day-to-day differences have only little effect on the result. The only exception appears to be the pNN50 parameter, the use of which should be favorably substituted by the rMSSD measurement. Geometric estimates of HR variability are highly and consistently correlated with statistical measures of overall HR variability, and may be used as substitutes for each other.

Adult↗
PubMed1994

Short- and long-term reproducibility of QT, QTc, and QT dispersion measurement in healthy subjects.

The study investigated interobserver and intrasubject reproducibility of QT interval duration and dispersion measured in standard 12-lead ECGs recorded at 25 mm/sec. Twenty-eight healthy volunteers were studied. Each underwent four ECG recordings, which were performed 1, 7, and 30 days apart. Two independent observers analyzed each ECG record. In each lead with a distinguishable T wave pattern, the RR interval, Q-peak of T interval, and Q-end of T interval were measured using a digitizing board with a 0.1-mm resolution. From each recording the following measures were derived: the maximum, minimum, and mean QT interval; maximum, minimum, and mean heart rate corrected QT interval (QTc); QT and QTc dispersion (the difference between the maximum and minimum QT interval among the 12 leads); and adjusted QT and QTc dispersion (dispersion divided by the square root of the number of leads measured). The interobserver and short-term (1 day) and long-term (1 week and 1 month) reproducibility of individual indices was assessed by computing the relative errors and comparing them by a standard sign test. In addition, the distributions of maximum and minimum QTc values among electrocardiographic leads, and the differences between QT-end and QT-peak based measurements were investigated. The results showed that: (1) the measurement of the QT interval from standard ECG recordings is feasible and not operator dependent (interobserver relative error < 4%); (2) the duration of the QT interval in healthy volunteers is stable and its short- and long-term reproducibility is high (intrasubject relative error < 6%); (3) parameters that characterize dispersion of the QT interval in the 12-lead ECG are highly nonreproducible, both between subsequent recording (relative error of 25%-35%) and between observers (relative error 28%-33%), the reproducibility of QT dispersion is significantly lower than that of QT duration (P < 0.01); and (4) the duration of the entire QT interval correlates only weakly with the duration of the Q-peak of T interval.

Adult↗
PubMed1994

Adjustment of QT dispersion assessed from 12 lead electrocardiograms for different numbers of analysed electrocardiographic leads: comparison of stability of different methods.

OBJECTIVE: Normal electrocardiographic recordings were analysed to establish the influence of measurement of different numbers of electrocardiographic leads on the results of different formulas expressing QT dispersion and the effects of adjustment of QT dispersion obtained from a subset of an electrocardiogram to approximate to the true QT dispersion obtained from a complete electrocardiogram. SUBJECTS AND METHODS: Resting 12 lead electrocardiograms of 27 healthy people were investigated. In each lead, the QT interval was measured with a digitising board and QT dispersion was evaluated by three formulas: (A) the difference between the longest and the shortest QT interval among all leads; (B) the difference between the second longest and the second shortest QT interval; (C) SD of QT intervals in different leads. For each formula, the "true" dispersion was assessed from all measurable leads and then different combinations of leads were omitted. The mean relative differences between the QT dispersion with a given number of omitted leads and the "true" QT dispersion (mean relative errors) and the coefficients of variance of the results of QT dispersion obtained when omitting combinations of leads were compared for the different formulas. The procedure was repeated with an adjustment of each formula dividing its results by the square root of the number of measured leads. The same approach was used for the measurement of QT dispersion from the chest leads including a fourth formula (D) the SD of interlead differences weighted according to the distances between leads. For different formulas, the mean relative errors caused by omitting individual electrocardiographic leads were also assessed and the importance of individual leads for correct measurement of QT dispersion was investigated. RESULTS: The study found important differences between different formulas for assessment of QT dispersion with respect to compensation for missing measurements of QT interval. The standard max-min formula (A) performed poorly (mean relative errors of 6.1% to 18.5% for missing one to four leads) but was appropriately adjusted with the factor of 1/square root of n (n = number of measured leads). In a population of healthy people such an adjustment removed the systematic bias introduced by missing leads of the 12 lead electrocardiogram and significantly reduced the mean relative errors caused by the omission of several leads. The unadjusted SD was the optimum formula (C) for the analysis of 12 lead electrocardiograms, and the weighted standard deviation (D) was the optimum for the analysis of six lead chest electrocardiograms. The coefficients of variance of measurements of QT dispersion with different missing leads were very large (about 3 to 7 for one to four missing leads). Independently of the formula for measurement of QT dispersion, omission of different leads produced substantially different relative errors. In 12 lead electrocardiograms the largest relative errors (> 10%) were caused by omitting lead aVL or lead V1. CONCLUSIONS: Because of the large coefficients of variance, the concept of adjusting the QT dispersion for different numbers of electrocardiographic leads used in its assessment is difficult if not impossible to fulfil. Thus it is likely to be more appropriate to assess QT dispersion from standardised constant sets of electrocardiographic leads.

Adult↗
PubMed1993

Long-term reproducibility of individual indices of time-domain analysis, spectral temporal mapping, and spectral turbulence analysis of signal-averaged ECGs.

This study compared short-term (1 day) and long-term (1 week and 1 month) reproducibility of the numerical results of 21 individual indices of time-domain analysis, spectral temporal mapping, and spectral turbulence analysis of the signal-averaged electrocardiogram in 28 healthy volunteers (18 men, 10 women, mean age, 31 years; range, 22-39 years). For each of the 21 indices and for each of the repeated recordings (ie, recordings on day 1, 7, and 30), the mean relative error versus recording of day 0 was calculated together with the rank correlation coefficient. The study showed that (1) reproducibility of time-domain analysis with the 40-Hz high-pass filter was superior to that of time-domain analysis performed with the 25-Hz high-pass filter, (2) reproducibility of time-domain variables was similar to that of spectral turbulence analysis of the entire QRS complex and was superior to that of spectral temporal mapping, (3) reproducibility of frequency-domain techniques not based on time-domain measurements (such as spectral turbulence analysis of the entire QRS complex) was significantly better than that of frequency-domain techniques combined with time-domain measurements (such as spectral turbulence analysis of the low-power terminal QRS region or spectral temporal mapping), and (4) short- and long-term reproducibility of signal-averaged electrocardiographic indices is similar in a healthy population.

Adult↗
PubMed1992

Acoustic appearance of atrial septal aneurysm.

Atrial septal aneurysm in the otherwise normal heart is a very rare and usually asymptomatic condition. A midsystolic click was described as the only clinical manifestation so far. A low-pitched early-to-midsystolic acoustic phenomenon in a 39-year-old woman corresponding with maximal leftward motion of the aneurysmatic interatrial septum during early systole is the subject of this case report. Our experience, plus review of the literature, supports the suggestion that atrial septal aneurysm should be considered in the interpretation of added systolic sounds.

Adult↗
PubMed1991

[A mobile thrombus simulating a myxoma of the right atrium].

Two-dimensional echocardiography is due to the detailed visualization of the right atrium and adjacent structures an indispensible non-invasive method for the detection pathological masses. In the differential diagnosis of these masses most frequently a mobile thrombus and myxoma are involved. The authors are presenting the case-history of a 71-year-old female patient where during hospitalization on account of a suspect non-Q-wave myocardial infarction in an anteroseptal position echocardiography revealed a pathological mass in the right atrium. From the case-history and results of examinations it was not possible to evaluate unequivocally the nature of the revealed mass. In view of the considerable risk of embolization into the pulmonary artery and coinciding ischaemic heart disease the patient was indicated for surgery and a mobile thrombus was removed. The described case draws attention to the differential diagnosis of right atrial masses and the optimal therapeutic approach.

Aged↗
PubMed1990

[Arteriovenous fistula complicating central venous catheterization].

Iatrogenic fistulae are sporadic but potentially serious complications of catheterization of central veins. The authors present the case-history of a 57-year-old patient with chronic renal failure where after 19 months following temporary insertion of a central venous catheter into the subclavian vein on the right from and infraclavicular approach a continual murmur was recorded in the right subclavicular area, along with increasing manifestations of left-sided cardiac insufficiency. Using digital subtraction angiography, the authors diagnosed an arteriovenous fistula between the internal thoracic artery and the right brachiocephalic vein. The described case draws attention to a rare complication of catheterization of the central veins and its possible haemodynamic sequelae.

Arteriovenous Fistula↗
PubMed1990

[Color-coded doppler echocardiography in atrial septal defects].

The magnitude of a left-to-right shunt in atrial septal defects was evaluated independently in catheterizations of the heart according to saturations and characteristics of the shunt stream in colour-flow Doppler echocardiography. The ratio of the pulmonary and systemic flow (Qp/Qs) assessed in 14 patients with atrial septal defects during catheterization correlated significantly with the maximal breadth (r = 0.8; p less than 0.001) and maximum area (r = 0.78; p less than 0.01) of the visualized shunted stream in transthoracic colour-flow Doppler echocardiography. Examination by means of transoesophageal colour-flow Doppler echocardiography in 8 patients revealed a correlation only with the maximal breadth of the shunted stream (r = 0.95; p less than 0.001). The magnitude of the maximum area of the shunted stream in transthoracic colour-flow Doppler echocardiography made it only possible to differentiate patients with a significant and not significant left-to-right shunt, i.e. Qp/Qs greater or smaller than 1.5:1. All patients with a shunt greater than 1.5:1 had a maximal area of the shunted stream greater than 10 sq.cm or 6 sq.cm/sq.m resp. Colour-flow Doppler echocardiography is a suitable method for the semiquantitative evaluation of the haemodynamic significance of atrial septal defects in adult patients.

Adolescent↗
PubMed1990

[Vasodilation effects of prostaglandin E1 in patients with precapillary pulmonary hypertension].

Prostaglandin E1. (Prostavasin, Schwarz, FRG) was administered in a short-term infusion, 5-30 ng/kg/min., to five patients with precapillary pulmonary hypertension associated with lung disease. Significant pulmonary vasodilatation characterized by a drop of the median pressure in the pulmonary artery by 15% and of the pulmonary vascular resistance by 31% was achieved only in two patients. The authors observed a minimal incidence of side-effects; systemic hypotension observed in three patients was an undesirable manifestaútion. Prostaglandin E1 extends possibilities of a vasodilatating influence on precapillary pulmonary hypertension in lung disease. With regard to the different individual reactivity of patients it should be administered in this indication only under conditions of haemodynamic monitoring.

Adult↗
PubMed1990

DSA diagnosis of pulmonary embolization from intracardial thrombus in a patient with permanent pacing catheter.

Pulmonary embolization in patients with implanted pacemakers is rare and an intracardiac thrombus attached to the distal end of a newly implanted ventricular endocardial electrode following removal of a previously implanted lead is a curiosity. We have documented such a case by digital subtraction angiography, a minimally invasive procedure that demonstrates both an intracardiac thrombus and secondary pulmonary embolization in a single procedure, which also allows simplified follow-up evaluation following therapy.

Angiography, Digital Subtraction↗