PubMed Health⌕ Search

Biomedical subjects

Eduardo Back Sternick

Publications and source records attributed to Eduardo Back Sternick.

At least 19 recordsLinked to original sources
PubMed2006

Familial pseudo-Wolff-Parkinson-White syndrome.

INTRODUCTION: PRKAG2 plays a role in regulating metabolic pathways, and mutations in this gene are associated with familial ventricular preexcitation, hypertrophic cardiomyopathy, and atrioventricular conduction disturbances. Clinico-pathologic and experimental data suggest the hypothesis of a glycogen storage disease. OBJECTIVE: To report a unique pattern of clinical features observed in individuals with a mutant PRKAG2 from two unrelated families. METHODS AND RESULTS: We studied two large families and found a total of 20 affected individuals showing a combination of sinus bradycardia, short PR interval, RBBB, intra and infrahisian conduction disturbances often requiring a pacemaker, and atrial tachyarrhythmias. Three individuals died suddenly at a young age. No patient had the Wolff-Parkinson-White (WPW) syndrome, and only two patients (10%) had myocardial hypertrophy. We performed screening of the exons and exon-intron boundaries of PRKAG2. Genetic analysis revealed a missense mutation (Arg302Gln) in the affected individuals from both families. This mutation had been described before and has been associated with the familial form of the WPW syndrome and with a high prevalence of left ventricular hypertrophy. CONCLUSION: PRKAG2 mutations are responsible for a diverse phenotype and not only the familial form of the WPW syndrome. Familial occurrence of right bundle branch block, sinus bradycardia, and short PR interval should raise suspicion of a mutant PRKAG2 gene.

Adult↗
PubMed2006

The 12-lead ECG in patients with Mahaim fibers.

The aim of this review article is to discuss the electrocardiographic presentation of the so called variants of pre-excitation ("Mahaim fibers") during sinus rhythm and tachycardia.

Diagnosis, Differential↗
PubMed2005

Electrocardiogram in patients with fasciculoventricular pathways: a comparative study with anteroseptal and midseptal accessory pathways.

OBJECTIVES: The purpose of this study was to describe the ECG profile of a cohort of patients with fasciculoventricular pathways and compare the profile with the ECG of patients with anteroseptal and midseptal accessory pathways. BACKGROUND: Electrophysiologic findings suggest fasciculoventricular pathways insert into the septal region. Findings also suggest the 12-lead surface ECG during sinus rhythm is similar to the ECG of patients with anteroseptal and midseptal bypass tracts. METHODS: Four different observers analyzed the 12-lead ECG of seven patients with fasciculoventricular pathways (group I) and the ECG of 20 patients with midseptal AV accessory pathways (group II) and 20 patients with anteroseptal AV accessory pathways (group III). The following variables were analyzed: ECG frontal plane QRS and delta wave axis; angle between the QRS and the delta wave axis; QRS width; R/S ratio in lead III; presence of a negative delta wave in inferior leads; and precordial lead transition to R/S >1. RESULTS: The ECG of fasciculoventricular pathways shows a variable pattern. It shares some features with an anteroseptal accessory pathway and others with a midseptal accessory pathway. A narrower QRS width was the most important variable in distinguishing a fasciculoventricular pathway from a septally located AV bypass tract (P <.0001). The angle between the QRS and the delta wave frontal plane axis could differentiate a fasciculoventricular pathway from an anteroseptal bypass tract (P <.0001) but not from a midseptal accessory pathway. CONCLUSIONS: The sinus rhythm ECG of patients with fasciculoventricular pathways shows similarities with ECGs of patients with anteroseptal and midseptal accessory pathways, but the QRS complex usually is narrower. The ECG recorded during sinus rhythm cannot reliably differentiate fasciculoventricular pathways with a broad QRS complex from anteroseptal or midseptal bypass tracts.

Adult↗
PubMed2005

Short atrioventricular Mahaim fibers: observations on their clinical, electrocardiographic, and electrophysiologic profile.

UNLABELLED: Short A-V manheim fiber. INTRODUCTION: A short atrioventricular decrementally conducting accessory pathway is an uncommon variant of preexcitation. Available data from small series suggest that their decremental properties might not be caused by A-V nodal-like tissue. METHODS: We compared clinical, electrocardiographic and electrophysiologic parameters in two groups of patients: 8 patients with a short A-V Mahaim pathway (Group A), and 33 patients with atriofascicular pathways (Group B). Radiofrequency catheter ablation was carried out guided by activation mapping at the annulus in Group A patients and targeting the "M" potential in Group B patients. RESULTS: After ablation of all associated rapidly conducting bypass tracts, 7 of the 8 Group A patients showed clear preexcitation. In only 1 of 8 patients the short A-V Mahaim fiber was actively engaged in a reentrant tachycardia circuit. During radiofrequency catheter ablation an automatic rhythm occurred in 4 of 8 patients. Intravenous adenosine caused conduction a block in the Mahaim fiber in 3 of the 5 patients tested. In group B, no patient showed clear preexcitation (P<00001) while 72% had a minimal preexcitation pattern. Twenty-nine of the 33 patients had a circus movement tachycardia with AV conduction over the atriofascicular fiber. During radiofrequency catheter ablation 30 of 33 patients showed accessory pathway automaticity. Adenosine caused transient block at the atriofascicular pathway in 11 (92%) of the 12 patients tested. CONCLUSIONS: While short decrementally conducting right-sided accessory pathways show a typical ECG pattern different from atriofascicular pathways, their electrophysiologic properties do not seem to be uniform. Those pathways can be successfully interrupted by catheter ablation.

Adenosine Triphosphate↗
PubMed2004

The electrocardiogram during sinus rhythm and tachycardia in patients with Mahaim fibers: the importance of an "rS" pattern in lead III.

OBJECTIVES: The purpose of the study was to identify the electrocardiographic (ECG) characteristics of the Mahaim fiber. BACKGROUND: Mahaim fibers are slowly conducting accessory pathways reaching into the right ventricle. They often play a role in tachycardias. METHODS: We retrospectively analyzed 40 patients with Mahaim fibers. Five patients had associated Wolff-Parkinson-White syndrome and were excluded from the study. Two patients had a short atrioventricular decremental accessory pathway and were also excluded. The remaining 33 patients had a tachycardia with anterograde conduction over a Mahaim fiber. Twenty were female. Their mean age was 24 +/- 10 years. RESULTS: The most common pattern of minimal preexcitation during sinus rhythm was an rS pattern in lead III. This was found in 20 patients. There was a match between the presence of rS in lead III during sinus rhythm and left axis deviation during tachycardia with anterograde conduction over the Mahaim fiber. After ablation, a different QRS pattern emerged in lead III, indicating the absence of conduction over the Mahaim fiber. To obtain information on the prevalence of an rS pattern in lead III in age-matched controls with palpitations and without structural heart disease, the 12-lead ECG of 200 young individuals were examined. An rS pattern in lead III was found in 6%. CONCLUSIONS: A narrow QRS with an rS pattern in lead III during sinus rhythm in a patient with a history of palpitations should alert the physician to the possibility of a Mahaim fiber. During tachycardia, these patients typically show a left bundle branch block-like QRS complex with left axis deviation.

Adolescent↗
PubMed2004

Electrocardiogram during tachycardia in patients with anterograde conduction over a Mahaim fiber: old criteria revisited.

OBJECTIVES: The aim of this study was to prospectively evaluate the sensitivity, specificity, and positive and negative predictive values of previously described ECG criteria to identify preexcited tachycardia due to decrementally conducting accessory pathways (QRS axis between 0 and -75 degrees , QRS width < or = 0.15 seconds, an R wave in lead I, an rS pattern in lead V(1), RS > 1 QRS transition > V(4), and cycle length between 220 and 450 ms). BACKGROUND: Preexcited tachycardia associated with decrementally conducting right-sided accessory pathways usually shows a rather "narrow" QRS complex and can be difficult to differentiate from supraventricular tachycardia (SVT) with left bundle branch block (LBBB) aberrant conduction. METHODS: We analyzed three groups of patients: 32 patients with an atriofascicular pathway (group I); 8 patients with long (n = 3) or short (n = 5) decrementally conducting right-sided AV pathway (group II); and a control group that consisted of 35 patients with SVT and LBBB (group III). RESULTS: Presence of all six criteria had 87.5% sensitivity in group I and a 0% sensitivity in group II. There were four false negatives in group I. The negative predictive value was 82.5%, with six false positives in group III (five patients with an aberrant LBBB-shaped tachycardia with ventriculoatrial conduction over an accessory AV pathway). The criterion cycle length was not helpful. CONCLUSIONS: Criteria for identifying a tachycardia with anterograde conduction over a Mahaim fiber are helpful only in atriofascicular pathways, with a sensitivity of 87.5% and a negative predictive value of 82.5%. The major cause of false positives was a tachycardia with aberrant LBBB conduction and ventriculoatrial conduction over an accessory AV pathway.

Adolescent↗
PubMed2004

Mahaim fiber: an atriofascicular or a long atrioventricular pathway?

There is debate concerning the distal insertion of Mahaim fibers. Some findings favor an atriofascicular fiber connected with the distal right bundle branch. Other findings favor a long atrioventricular (AV) structure inserting into the myocardium. A patient having a decrementally conducting accessory pathway is reported. Proximal and distal Mahaim potentials were recorded during sinus rhythm, atrial pacing, and antidromic tachycardia. Both proximal and distal M potentials always preceded the QRS complex during sinus rhythm and antidromic tachycardia earlier than the right bundle branch potential. During tachycardia, the distal M potential was recorded 6 ms before the retrograde right bundle potential. Other arguments consistent with an AV connection were a change in the QRS configuration during tachycardia after the first radiofrequency pulse at the site of the distal M potential and absence of right bundle branch block after successful ablation. Conduction through the proximal part of the Mahaim fiber was unaltered after ablation, as assessed by recording the proximal M potential. Electrophysiologic evidence is presented suggesting a long AV accessory pathway inserting close to the distal right bundle branch rather than an atriofascicular connection in this patient with a Mahaim fiber.

Action Potentials↗
PubMed2004

Automaticity in Mahaim fibers.

INTRODUCTION: Automatic rhythms associated with Mahaim fibers usually occur during radiofrequency catheter ablation. The incidence and significance of spontaneous automaticity in Mahaim fibers are unknown. METHODS AND RESULTS: Spontaneous automatic rhythms were observed in 5 (12.5%) of 40 patients with Mahaim fibers referred for nonpharmacologic therapy because of recurrent episodes of symptomatic tachyarrhythmias, usually antidromic circus movement tachycardia (33/40 patients). Three were female and two were male. Their mean age was 15 +/- 7 years compared to 26 +/- 13 years of the patients without automaticity (P = 0.09). Three patients had both antidromic tachycardia and asymptomatic spontaneous automatic rhythms recorded during ambulatory ECG (1 patient) or electrophysiologic study (2 patients). In 2 patients, the automatic rhythm triggered antidromic tachycardia. Two other patients had nonsustained repetitive episodes of wide QRS tachycardia due to automaticity arising in the Mahaim fiber, without antidromic tachycardia. All automatic rhythms were abolished by successful catheter ablation of the Mahaim fibers. CONCLUSION: Spontaneous automaticity occurred in 12.5% of our Mahaim patients and may trigger antidromic tachycardia. Spontaneous automaticity, which is not seen in rapidly conducting accessory pathways, is another argument for the presence of an AV nodal-like structure in Mahaim fibers.

Adolescent↗
PubMed2004

Dual conduction in a Mahaim fiber.

The case of an 8-year-old girl with incessant nonsustained left bundle branch block-like tachycardia refractory to antiarrhythmic drug therapy is reported. Electrophysiologic study revealed the presence of a right-sided accessory atriofascicular pathway. Episodes of nonsustained tachycardia were found to be based upon a dual response in AV conduction over the Mahaim fiber to one P wave. No reentrant tachycardia could be induced. The arrhythmia was cured by catheter ablation targeting a Mahaim potential at the right lateral tricuspid annulus. The findings can be explained by longitudinal dissociation in a single Mahaim fiber, a fiber distally diverging into two fibers with different conduction times, or (less likely) two closely located Mahaim fibers with different conduction times.

Bundle-Branch Block↗
PubMed2004

Radiofrequency catheter ablation of an accessory pathway in a patient with Wolff-Parkinson-White and Kartagener's syndrome.

We report a case of a manifest left free wall accessory pathway in a patient with Kartagener's syndrome and recurrent episodes of orthodromic atrioventricular reentrant tachycardia. To the best of our knowledge, it is the first report of Wolff-Parkinson-White syndrome associated with Kartagener's syndrome. Situs inversus and mirror image dextrocardia occurred with no additional detectable cardiac structural abnormalities. Diagnostic and therapeutic electrophysiological study was carried out via transaortic approach and a left-to-right reversal of monoplane fluoroscopic image.

Catheter Ablation↗