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M Karch

Publications and source records attributed to M Karch.

15 recordsLinked to original sources
PubMed2000

Relationship between surface electrocardiogram characteristics and endocardial activation sequence in patients with typical atrial flutter.

OBJECTIVES: The relationships that exist between endocardial and surface electrocardiogram (ECG) activity in patients with AFl have not been satisfactorily delineated. The aim of the study was to determine the relationships that exist between the atrial endocardial activity and the surface ECG in patients with atrial flutter (AFl). METHODS: In 40 patients with AFl, a 64-electrode basket catheter (BC) was deployed in the right atrium (RA). A decapolar catheter was inserted into the coronary sinus (CS) to record from the left atrium. The temporal relationship between endocardial and surface ECG activity was determined by means of electronic calipers. RESULTS: In counterclockwise AFl, the activation of the lateral wall of RA coincided with the positive deflections in lead I, V1 and V6 and the upstroke component in inferior leads. Plateau duration in lead III (121 +/- 27 ms) correlated strongly with isthmus conduction time (117 +/- 23 ms) (r = 0.91). Septal and left atrial conduction coincided with negative components in lead I, inferior leads and V6 and positive deflections in leads aVL and V1. In clockwise AFl, the F wave was notched in all ECG leads. The first component resulted from the activation of the septum and posterior wall of the RA. The second component was coincident with activity recorded in CS electrograms. The interval between the two deflections (60 +/- 18 ms) correlated strongly with interatrial conduction time (57 +/- 19 ms) (r = 0.84). Interatrial conduction interval was prolonged during AFl as compared to sinus rhythm (60 +/- 18 ms vs 43 +/- 13 ms, p = 0.04). Activation of the lateral wall of RA coincided with the negative components in lead I, inferior leads and V6. CONCLUSIONS: The electrical activity in surface ECG closely correlates with conduction in specific parts of the atria. Polarity of the F wave in an ECG lead is determined by a resultant of opposing activities from the lateral wall of the RA and the left atrium.

Aged↗
PubMed2000

Block of the lower interatrial connections: insight into the sources of electrocardiographic diversities in common type atrial flutter.

Whether the conduction disturbances of the interatrial connections play a role in the genesis of ECG variants of atrial flutter is almost completely unknown. We present a patient with typical counterclockwise atrial flutter in whom the ablation of the coronary sinus (CS) area during ongoing atrial flutter produced significant ECG changes without alterations in the activation sequence within the right atrium (RA). This case highlights the possible role of alterations of the interatrial connections in the genesis of atypical ECG manifestations of common type atrial flutter.

Aged↗
PubMed2000

Basket catheter-guided three-dimensional activation patterns construction and ablation of common type atrial flutter.

Construction of three-dimensional activation maps and evaluation of ablation-created bidirectional block in the tricuspid valve-inferior vena caval (TV-IVC) isthmus in patients with atrial flutter (AF) are difficult with conventional mapping technique. In 36 patients with type I AF (25 men, 11 women; mean age 62 +/- 10.5 years) a multielectrode basket catheter (BC) was deployed in the right atrium (RA). Out of 64 BC electrodes, 56 bipolar electrograms were derived. Three-dimensional activation patterns were constructed with a software program. Stable electrograms of satisfactory quality were obtained in 49 +/- 2 electrode pairs. Capture was possible in 36 +/- 3 of bipoles. In counterclockwise AF (CCW-AF) and clockwise AF (CW-AF) episodes, cycle lengths and TV-IVC isthmus conduction times were 248 +/- 26 ms and 251 +/- 23 ms, (P = 0.74) and 105 +/- 28 ms and 106 +/- 33 ms (P = 0.92), respectively. Conduction velocity in the TV-IVC isthmus was lower than in the anterior or septal limbs of the circuit, in counterclockwise or clockwise episodes. Double potentials were recorded in 94% of patients. Three-dimensional activation patterns were delineated and displayed as isochronal maps. The reentry circuit involved the TV-IVC isthmus, septal, and anterior walls and a part of the RA roof anterior to superior vena cava. Postablation isthmus conduction was evaluated through the sequence criteria, local electrogram-based criteria, and the analysis of three-dimensional activation patterns of the paced rhythms. The complete isthmus block was associated with a significant increase of the low anterior low septal conduction interval (152 +/- 29 vs 104 +/- 32 ms, P = 0.001) and the low septal-low anterior conduction interval (150 +/- 31 vs 107 +/- 33 ms, P = 0.001). Radiofrequency ablation was successful in 32 (90%) of 36 patients. In conclusion, the current mapping system enables construction of three-dimensional activation patterns and facilitates evaluation of the postablation TV-IVC isthmus block in patients with AF.

Adult↗
PubMed1999

Clinical experience with a novel multielectrode basket catheter in right atrial tachycardias.

BACKGROUND: The complexity of atrial tachycardias (ATs) makes the electroanatomic characterization of the arrhythmogenic substrate difficult with conventional mapping techniques. The aim of our study was to evaluate possible advantages of a novel multielectrode basket catheter (MBC) in patients with AT. METHODS AND RESULTS: In 31 patients with AT, an MBC composed of 64 electrodes was deployed in the right atrium (RA). The possibility of deployment, spatial relations between MBC and RA, MBC recording and pacing capabilities, mapping performance, and MBC-guided ablation were assessed. MBC deployment was possible in all 31 patients. The MBC was left in the RA for 175+/-44 minutes. Stable bipolar electrograms were recorded in 88+/-4% of electrodes. Pacing from bipoles was possible in 64+/-5% of electrode pairs. The earliest activity intervals, in relation to P-wave onset, measured from the MBC and standard roving catheters were 41+/-9 and 46+/-6 ms, respectively (P=0.21). Radiofrequency ablation was successful in 15 (94%) of 16 patients in whom it was attempted, including 2 patients with polymorphic right atrial tachycardia (RAT), 2 with RAT-atrial flutter combination, 1 with macroreentrant AT, and 1 with focal origin of atrial fibrillation. CONCLUSIONS: These data demonstrate that MBC can be used safely in patients with right atrial arrhythmias. The simultaneous multielectrode mapping aids in the rapid identification of sites of origin of the AT and facilitates radiofrequency ablation procedures. The technique is especially effective for complex atrial arrhythmias.

Adult↗
PubMed1999

Computer-assisted animation of atrial tachyarrhythmias recorded with a 64-electrode basket catheter.

OBJECTIVES: The aim of this study was to assess the value of a new mapping technique based on computer-assisted animation of multielectrode basket catheter (BC) recordings in patients with atrial arrhythmias. BACKGROUND: The three-dimensional activation patterns of cardiac arrhythmias are not completely understood owing to limitations of conventional mapping techniques. METHODS: The study included 32 patients with atrial tachycardia (AT) and 38 patients with atrial flutter (AFL). A software program was developed to analyze the activation patterns based on 56 bipolar electrograms recorded with a 64-electrode BC deployed in the right atrium (RA). RESULTS: The total time needed for the animation of activation patterns of atrial arrhythmias was 5 +/- 0.8 min. In 22 patients with right AT, the animated maps revealed that arrhythmia was unifocal in 15 patients, multifocal in 2 patients, polymorphic in 4 patients and reentrant in 1 patient. In 10 patients with left AT, breakthroughs on the right side of the septum (2 in 8 patients and 1 in 2 patients) and a left-to-right activation of the RA were demonstrated. In patients with typical AF, the reentrant excitation was a broad activation front with preferential propagation around the tricuspid annulus. In patients with atypical AFL, the reentry circuit involved one of the venae cavae and a line of block located in the posterior wall. CONCLUSIONS: The computer-assisted animation of multiple electrograms recorded with a BC is a valuable mapping tool that delineates the three-dimensional activation patterns of various atrial arrhythmias. The technique is appropriate for complex, short-lived or unstable arrhythmias.

Adult↗
PubMed1998

[Cardiac pacemaker and internal defibrillators (ICD). Basic principles and new important developments, status 1998].

In recent years, treatment of cardiac arrhythmias with pacemakers and implantable cardioverter/defibrillators has become increasingly popular. Numerous technical developments have resulted in great advances in this area. International pacing letter coding for use with pacemakers defines the chamber(s) paced, the chamber in which the electrical activity is sensed, and the type of pacing. This also enables the family doctor involved in the care of the cardiac patient to identify the pacemaker system employed and provides him with initial orientation. New developments including VDD pacing, autocapture and autosensing are described and discussed. In a second part, the conditions for the use, and the manner of functioning, of modern implantable cardioverter/defibrillators are explained.

Defibrillators, Implantable↗
PubMed1997

[Torsade de pointes tachycardia during administration of quinidine and verapamil in atrial fibrillation].

The following case report shows that life threatening arrhythmias with fatal consequences may occur after treatment with Cordichin a combination of 80 mg verapamil and 160 mg quinidine. A 65-year-old woman was treated with Cordichin due to atrial fibrillation lasting for 3 months. After the first day of treatment the patient suddenly collapsed with loss of consciousness. The patient was resuscitated 15 min later. The emergency physician diagnosed a cardiac arrest. After cardiopulmonary resuscitation and intubation stable circulation was restored. When the patient was admitted in our hospital the ECG showed numerous ventricular extrasystoles, marked prolongation of the QT interval (700 ms) (Figures 1a and b) and nonsustained polymorphic ventricular tachycardias (Figure 2). The arrhythmias could be suppressed by right ventricular stimulation after inserting a pacemaker lead. After a period of 12 h a normal QT interval was restored (Figure 3). Unfortunately the patient died 3 days later due to irreversible cerebral damage. The concept of suppressing proarrhythmic effects of quinidine by calcium antagonists is discussed. Despite theoretical advantages of a combination therapy this case report shows that life threatening dysrhythmias cannot be prevented by additional calcium antagonism.

Aged↗
PubMed1997

Rate-independent effects of the new class III antiarrhythmic agent ambasilide on transmembrane action potentials in human ventricular endomyocardium.

The electrophysiologic effects of ambasilide, a new class III antiarrhythmic drug reported to be a nonselective blocker of both components (I(Kr) and I(Ks)) of the delayed-rectifier potassium current (I(K)) and other repolarizing potassium currents (I(tol), I(so)), were studied in specimens of left ventricular endomyocardium of human hearts obtained from 10 patients undergoing either heart transplantation (n = 4) or mitral valve replacement (n = 6). We recorded transmembrane action potential (TAP) characteristics at different stimulation frequencies (0.5, 1, 1.5, and 2 Hz) and with different dosages of ambasilide (1, 10, and 50 microM) by using conventional microelectrode techniques. Beginning at a concentration of 10 microM ambasilide, the TAP duration at 90% repolarization (TAPD90) was significantly prolonged and independent of stimulation frequency with a mean percentage prolongation of 18% at 10 microM and 30% at 50 microM ambasilide. TAP duration at 50% repolarization was not significantly prolonged except for 10 microM ambasilide at 0.5 Hz (17%; p < 0.05). The frequency-independent action potential (AP) prolongation by ambasilide in human ventricular endomyocardium indicates that a nonselective block of repolarizing potassium currents seems to be more favorable than a selective block of I(Kr).

Action Potentials↗
PubMed1996

Low energy intracardiac cardioversion after failed conventional external cardioversion of atrial fibrillation.

OBJECTIVES: This study was designed to evaluate the efficacy of intracardiac cardioversion in patients with chronic atrial fibrillation after unsuccessful external cardioversion. BACKGROUND: Previous studies in patients with atrial fibrillation undergoing intracardiac cardioversion have suggested that intracardiac cardioversion is highly effective and safe. However, the characteristics of patients who benefit most from this invasive technique are unknown. METHODS: We prospectively studied 25 consecutive patients with chronic atrial fibrillation (11 +/- 9 months). All patients had undergone at least three attempts at conventional external transthoracic cardioversion by means of paddles in an anteroposterolateral position applying energies up to 360 J without success. Intracardiac shocks were delivered by an external defibrillator through defibrillation electrodes placed in the right atrium and coronary sinus or in the right atrium and left pulmonary artery. After conversion, all patients were treated orally with sotalol (mean 194 +/- 63 mg/day). RESULTS: Internal cardioversion was successful in 22 of 25 patients at a mean defibrillation threshold of 6.5 +/- 3.0 J. Mean lead impedance was 56.4 +/- 7.4 omega. No severe complications were observed. At a mean follow-up of 15 +/- 12 months, 12 (55%) of the patients treated successfully remained in sinus rhythm. CONCLUSIONS: In patients with failed external cardioversion, internal cardioversion offers a new option for restoring sinus rhythm. Intracardiac cardioversion is an effective and safe method and can be easily performed in patients with minimal sedation.

Adult↗
PubMed1996

Reimplantation of an infected, abdominally implanted defibrillator in the subpectoral region.

This report regards a 55-year-old patient with an abdominally implanted, nonthoracotomy, cardioverter defibrillator system (Medtronic PCD 7217B) due to recurrent ventricular tachycardia and survived sudden cardiac death. Fifteen months after defibrillator implantation clinical signs of system infection occurred. The defibrillator and the two leads (Medtronic 6963 and 6966) were removed and treatment with intravenous antibiotic therapy was started. Thereafter the original resterilized ICD was re-implanted in a right subpectoral position with new right ventricular-and superior vena cava leads. This report shows that reuse of the relatively large Medtronic PCD 7217B with a new transvenous lead system in a retropectoral location is feasible and economically beneficial with regard to the high device cost.

Anti-Bacterial Agents↗
PubMed1995

[Radiofrequency ablation in permanent ectopic left atrial tachycardia].

HISTORY AND FINDINGS: A 35-year-old symptom-free woman was known since childhood to have an increased resting heart rate (130-150/min). In the ECG there was a negative P in leads I and aVL, with a shortened P-Q interval of 90 ms. Previous treatment with beta-receptor blockers and calcium antagonists had failed. Clinical examination and echocardiography, as well as levels of thyroid hormone were unremarkable. During electrophysiological studies the earliest atrial activity was localised by endocardial leads in the region of the distal coronary sinus and the arrhythmia could not be terminated by atrial over-stimulation. TREATMENT AND COURSE: After transseptal puncture the ablation catheter was introduced into the left atrium and, the exact site of the origin of the atrial tachycardia having been established, radiofrequency ablation of this point was successfully performed. Subsequently the patient was always found to be in stable sinus rhythm at around 80/min. CONCLUSION: To prevent tachycardia-induced cardiomyopathy, radiofrequency ablation can be indicated even in symptom-free patients with atrial tachycardia.

Adult↗
PubMed1992

Sotalol exhibits reverse use-dependent action on monophasic action potentials in normal but not in infarcted canine ventricular myocardium.

In 12 anesthetized mongrel dogs (30 mg/kg pentobarbital), a thoracotomy was performed, and the left anterior descending coronary artery was ligated proximally. Eight to 12 days later, monophasic action potentials were recorded endocardially from the apex of the noninfarcted right ventricle and infarcted areas of the left ventricle, and the effects of 1.5 mg/kg intravenous sotalol were evaluated. Monophasic action potentials from the infarcted zone of the left ventricle were obtained from areas where fractionated bipolar electrograms could be recorded; this was histologically confirmed. After sotalol, in sinus rhythm, the monophasic action potential duration at 90% repolarization of the infarcted zone increased from 186 +/- 31 to 226 +/- 45 ms (+ 22%, p less than 0.05), and monophasic action potential duration of the noninfarcted zone increased from 184 +/- 31 to 225 +/- 47 ms (+ 22%, p less than 0.05). Programmed ventricular stimulation was performed with single extrastimuli at a basic drive cycle length of 300 ms. With long coupling intervals (290 ms), monophasic action potential duration of the infarcted zone increased from 165 +/- 23 to 183 +/- 25 ms (+ 11%, p less than 0.05) after sotalol; and monophasic action potential duration of the noninfarcted zone increased from 159 +/- 20 to 180 +/- 25 ms (+ 13%, p less than 0.05). With short coupling intervals (200 ms), the monophasic action potential duration of the noninfarcted zone increased from 157 +/- 19 to 173 +/- 18 ms (+ 10%, p less than 0.05), and monophasic action potential duration of the noninfarcted zone increased from 150 +/- 18 to 157 +/- 18 ms (+ 5%, NS).(ABSTRACT TRUNCATED AT 250 WORDS)

Action Potentials↗
PubMed1991

Reverse use-dependent effects of sotalol demonstrated by recording monophasic action potentials of the right ventricle.

In 22 patients referred for electrophysiologic study, monophasic action potentials (MAP) were recorded from the right ventricular aspect of the ventricular septum. The duration of MAP at 90% (MAP90) and 30% (MAP30) repolarization was measured in sinus rhythm, at a constant atrial paced cycle length of 600 ms for 3 minutes and at constant ventricular paced cycle lengths of 600, 500, 400 and 300 ms for 20 beats. Programmed ventricular stimulation from the apex of the right ventricle was performed at a basic drive cycle length of 400 ms and MAP90 and MAP30 of premature beats was determined. Changes of MAP duration were assessed 20 minutes after administration of intravenous sotalol 1.5 mg/kg. Sotalol significantly increased MAP90 and MAP30 in sinus rhythm. This was independent from sinus cycle length prolongation as evidenced by a significant prolongation of MAP90 and MAP30 with constant atrial pacing after sotalol. With slow ventricular stimulation frequencies and with long coupling intervals at programmed ventricular stimulation, sotalol significantly prolonged MAP90 and MAP30; with high stimulation frequencies and at short coupling intervals the action potential-prolonging effect of sotalol was diminished, indicating a reverse use-dependent effect of sotalol on repolarization of the right ventricle in humans.

Action Potentials↗
PubMed1991

Characteristics of endocardial monophasic action potentials recorded from areas with fractionated bipolar electrograms in infarcted canine ventricular myocardium.

STUDY OBJECTIVE: The aim was to characterise monophasic action potentials recorded from subacutely infarcted myocardial regions, where fractionated bipolar electrograms could be obtained. DESIGN: Dogs underwent ligation of the left anterior descending coronary artery. Before and 8-12 d after ligation, monophasic action potentials and local electrograms were recorded endocardially from the apex of the left ventricle. EXPERIMENTAL MATERIAL: 15 anaesthetised mongrel dogs (30 mg pentobarbitone.kg-1) were used. MEASUREMENTS AND MAIN RESULTS: Multiphasic fractionated bipolar electrograms could be recorded from infarcted sites of the left ventricle with a mean duration of 69(SD 10) ms and a mean amplitude of 3.7(1.6) mV, compared to control values of 42(7) ms (p less than 0.05) and 9.4(2.2) mV (p less than 0.05), respectively. Endocardial monophasic action potentials recorded from these areas were similar to action potentials obtained from non-infarcted sites before coronary ligation. The fractionated extracellular potentials were superimposed on the monophasic action potential upstroke. MAP90 was 189(31) ms, MAP30 138(12) ms, versus control values of 182(27) ms and 139(10) ms (NS). Monophasic action potential amplitude was significantly reduced at infarcted sites compared to control, at 26(7) mV v 38(6) mV. Histological specimens were taken to confirm that measurements were obtained from infarcted tissue. CONCLUSIONS: It is possible to record monophasic action potential in subacutely infarcted canine ventricular myocardium; this technique might help in further studies to characterise electrophysiological mechanisms of ventricular arrhythmias in chronic myocardial infarction in man.

Action Potentials↗