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Biomedical subjects

Z Blanck

Publications and source records attributed to Z Blanck.

63 records · Page 4Linked to original sources
PubMed1993

Electrophysiologic spectrum of atrioventricular nodal behavior in patients with atrioventricular nodal reentrant tachycardia undergoing selective fast or slow pathway ablation.

INTRODUCTION: The objective of this report is to delineate the atrioventricular (AV) nodal electrophysiologic behavior in patients undergoing fast or slow pathway ablation for control of their AV nodal reentrant tachycardia (AVNRT). METHODS AND RESULTS: One hundred sixteen consecutive patients with symptomatic AVNRT were included. Twenty-two patients underwent fast pathway ablation with complete abolition of AVNRT in all and development of complete AV block in five patients. Of 17 patients with intact AV conduction postablation, 12 had demonstrated antegrade dual pathway physiology during baseline study, which was maintained in three and lost in nine patients postablation. Two patients with successful fast pathway ablation developed uncommon AVNRT necessitating a slow pathway ablation. Twenty-one patients demonstrated both common and uncommon forms of AV nodal reentry during baseline study. The earliest site of atrial activation was close to the His-bundle recording site (anterior interatrial septum) during common variety and the coronary sinus ostium (posterior interatrial septum) during the uncommon AV nodal reentry in all 21 patients. Ninety-six patients underwent successful slow pathway ablation. Among these, the antegrade dual pathway physiology demonstrable during baseline study (60 patients) was maintained in 25 and lost in 35 patients postablation. CONCLUSION: These data suggest that: (1) dual pathway physiology may persist after successful ablation, which might be a reflection of multiple reentrant pathways in patients with AVNRT; and (2) the retrograde pathways during common and uncommon AVNRT have anatomically separate atrial breakthroughs. These findings have important electrophysiologic implications regarding the prevailing concept of the AV nodal physiology in patients with AVNRT.

Adolescent↗
PubMed1993

Bundle branch reentrant ventricular tachycardia: cumulative experience in 48 patients.

INTRODUCTION: The clinical, electrophysiologic features and follow-up of 48 patients with inducible bundle branch reentrant (BBR) tachycardia are presented. METHODS AND RESULTS: Forty-eight patients were identified in whom a diagnosis of BBR tachycardia was made during electrophysiologic evaluation. The clinical presentation was syncope or sudden death in 38 patients, and sustained palpitations during wide QRS complex tachycardia in 5 patients. Electrophysiologic studies were performed in 5 additional patients for various other reasons. Structural heart disease was present in 45 patients. Idiopathic dilated cardiomyopathy and coronary artery disease were the anatomical substrates in 19 (39%) and 24 (50%) patients, respectively, severe aortic regurgitation was present in 2 patients, and no organic heart disease was identified in 3. All 48 patients had evidence of His-Purkinje system disease. BBR tachycardia with left and right bundle branch block morphologies was induced in 46 and 5 patients, respectively, and interfascicular BBR tachycardia was initiated in 2 patients. Ventricular tachycardia of a myocardial origin was induced in 11 patients. Management of BBR tachycardia included transcatheter bundle branch ablation in 28 patients, and antiarrhythmic drug therapy in 16 patients. Four patients were treated with implantable defibrillators. After a mean follow-up of 15.8 months in 42 patients, there were 13 deaths due to congestive heart failure, 4 sudden cardiac deaths, 3 nonsudden cardiac deaths, and 3 noncardiac related deaths. CONCLUSION: Sustained BBR, a form of monomorphic ventricular tachycardia, is a highly malignant arrhythmia usually seen in patients with structural heart disease. Three different types of BBR tachycardia are described. If distinguished from ventricular tachycardia of a myocardial origin, catheter ablation of the right bundle branch can be easily performed and effectively eliminates BBR. During follow-up, congestive heart failure is the most common cause of death in this population.

Adult↗
PubMed1993

Atrioventricular nodal reentry. Clinical, electrophysiological, and therapeutic considerations.

BACKGROUND: Atrioventricular (AV) nodal reentry is a relatively common cause of regular, narrow QRS tachycardia. The underlying basis for this arrhythmia is functional (and anatomic) duality of pathways in the region of the AV node, although the exact boundaries of the reentrant circuit have not been convincingly defined. During the more common type of AV nodal reentry (seen in approximately 90% of cases), a slow conducting pathway is used in the anterograde direction, and a fast pathway is operative in the retrograde direction. In the uncommon form, the direction of impulse propagation within the reentrant circuit is reversed. In this article, the clinical, ECG, and electrophysiological features of AV nodal reentry as well as approaches to therapy are discussed. METHODS AND RESULTS: Clinical diagnosis may be made from the surface ECG. In the common type of AV nodal reentry, the P wave is obscured by the QRS or may be present in its terminal portion. The P wave in the uncommon form occurs late (i.e., in or after the T wave), producing a pattern of long RP and short PR. Both forms of AV nodal reentry are controllable with various therapeutic modalities. For acute termination, adenosine is probably the ideal agent. Prevention of recurrences can be achieved with several pharmacological agents, including beta-blockers, calcium channel blockers, and class Ia, Ic, and III antiarrhythmic agents. Curative therapy is now available with a variety of nonpharmacological methods. However, the most promising therapy at the present time is catheter modification of the AV node by ablation of either the fast or slow pathway, using radiofrequency energy. Ablation of the fast pathway carries a higher risk of second- or third-degree AV block. Slow pathway ablation, by providing a high rate of success and minimal risk of AV block, seems to be a more acceptable initial approach. CONCLUSIONS: AV nodal reentry is a common cause of paroxysmal supraventricular tachycardia, and a precise diagnosis can be made with intracardiac electrophysiological evaluation. Although the arrhythmia responds to a variety of antiarrhythmic agents, curative therapy can now be offered with catheter modification of the AV node using radiofrequency energy. At the time of this writing, it seems that catheter modification of the AV node is rapidly becoming the therapy of initial choice in patients with symptomatic AV nodal reentrant tachycardia requiring treatment.

Adult↗
PubMed1993

Control of supraventricular tachycardia with transcatheter ablative technique using radio frequency as the energy source.

Supraventricular tachycardia constitutes a significant clinical problem, frequently requiring medical intervention. We analyzed data in 413 consecutive patients with supraventricular tachycardia treated at our center with the catheter ablative technique and found the following outcome. Among 272 patients who had regular narrow QRS tachycardia without ventricular pre-excitation during sinus rhythm (Group I), control was achieved in all but one case (success rate 99.6%). Patients in Group II had ventricular pre-excitation during sinus rhythm and narrow or wide QRS tachycardia. Elimination of ventricular pre-excitation and control of the tachycardia was achieved in 104 of the 106 cases in this group (a success rate of 98%). Group III patients had atrial flutter-fibrillation as the predominate arrhythmia and control of rapid ventricular response was successfully achieved with atrioventricular junctional ablation in all 35 cases. Serious complications were related to anticoagulation and were seen in less than 2% of the cases. There were no instances of thromboembolic phenomena or death related to these procedures. It is concluded that the catheter ablative technique with radio frequency as the energy source is a highly effective means for control of supraventricular tachycardia with minimal associated risk of serious complications.

Adult↗
PubMed1993

Neurocardiogenic syncope. Diagnosis, mechanisms, and treatment.

Neurocardiogenic syncope is a common medical problem that can be identified easily by history and the findings of the head-up tilt test. Depressor reflexes from the heart causing sympathetic withdrawal that, in turn, lead to peripheral vasodilatation and hypotension may have an important role in the pathogenesis of neurocardiogenic dysfunction. Once a diagnosis of neurocardiogenic syncope has been made, specific therapeutic strategies can usually prevent recurrent syncope. However, the natural history of neurocardiogenic syncope has not been studied. Double-blind placebo-controlled studies or drug withdrawal trials are needed to assess whether all patients with neurocardiogenic syncope need lifelong therapy.

Autonomic Nervous System↗
PubMed1993

Implantable cardioverter-defibrillator therapy for prevention of sudden cardiac death.

Patients with known symptomatic VT or VF are at high risk for sudden cardiac death. Various therapeutic choices can be used to reduce the incidence of arrhythmic sudden cardiac death. These include beta-blockers, class I and III antiarrhythmic agents, VT focal ablations, and ICD therapy. The overall incidence of sudden cardiac death in ICD recipients is less than 2% per year, a rate of survival not achieved with any of the available antiarrhythmic agents. VT surgical therapy can produce comparable survival results, but the minimal operative mortality is higher than that with ICD therapy. In patients with noninducible VT/VF or inducible polymorphic VT, and in those refractory to or intolerant of antiarrhythmic agents and poor left ventricular function, ICD therapy may be the only realistic option.

Death, Sudden, Cardiac↗
PubMed1992

Selective transcatheter ablation of the fast and slow pathways using radiofrequency energy in patients with atrioventricular nodal reentrant tachycardia.

BACKGROUND: The safety and efficacy of selective fast versus slow pathway ablation using radiofrequency energy and a transcatheter technique in patients with atrioventricular nodal reentrant tachycardia (AVNRT) were evaluated. METHODS AND RESULTS: Forty-nine consecutive patients with symptomatic AVNRT were included. There were 37 women and 12 men (mean age, 43 +/- 20 years). The first 16 patients underwent a fast pathway ablation with radiofrequency current applied in the anterior/superior aspect of the tricuspid annulus. The remaining 33 patients initially had their slow pathway targeted at the posterior/inferior aspect of the right interatrial septum. The fast pathway was successfully ablated in the initial 16 patients and in three additional patients after an unsuccessful slow pathway ablation. A mean of 10 +/- 8 radiofrequency pulses were delivered; the last (successful) pulse was at a power of 24 +/- 7 W for a duration of 22 +/- 15 seconds. Four of these 19 patients developed complete atrioventricular (AV) block. In the remaining 15 patients, the post-ablation atrio-His intervals prolonged from 89 +/- 30 to 138 +/- 43 msec (p less than 0.001), whereas the shortest 1:1 AV conduction and effective refractory period of the AV node remained unchanged. Ten patients lost their ventriculoatrial (VA) conduction, and the other five had a significant prolongation of the shortest cycle length of 1:1 VA conduction (280 +/- 35 versus 468 +/- 30 msec, p less than 0.0001). Slow pathway ablation was attempted initially in 33 patients and in another two who developed uncommon AVNRT after successful fast pathway ablation. Of these 35 patients, 32 had no AVNRT inducible after 6 +/- 4 radiofrequency pulses with the last (successful) pulse given at a power of 36 +/- 12 W for a duration of 35 +/- 15 seconds. After successful slow pathway ablation, the shortest cycle length of 1:1 AV conduction prolonged from 295 +/- 44 to 332 +/- 66 msec (p less than 0.0005), the AV nodal effective refractory period increased from 232 +/- 36 to 281 +/- 61 msec (p less than 0.0001), and the atrio-His interval as well as the shortest cycle length of 1:1 VA conduction remained unchanged. No patients developed AV block. Among the last 33 patients who underwent a slow pathway ablation as the initial attempt and a fast pathway ablation only when the former failed, 32 (97%) had successful AVNRT abolition with intact AV conduction. During a mean follow-up of 6.5 +/- 3.0 months, none of the 49 patients had recurrent tachycardia. Forty patients had repeat electrophysiological studies 4-8 weeks after their successful ablation, and AVNRT could not be induced in 39 patients. CONCLUSIONS: These data suggest that both fast and slow pathways can be selectively ablated for control of AVNRT: Slow pathway ablation, however, by obviating the risk of AV block, appears to be safer and should be considered as the first approach.

Adult↗