Postablation-acquired short atrioventricular Mahaim-type fibers: observations on their clinical, electrocardiographic, and electrophysiologic profile.

BACKGROUND: The electrophysiologic characteristics of decrementally conducting accessory pathways (APs) are well described; however, little is known about decrementally conducting APs caused by the radiofrequency ablation of a rapidly conducting AP. OBJECTIVE: To report the clinical, electrocardiographic, and electrophysiologic characteristics of 6 patients who developed a decremental AP after an attempt at ablation. METHODS: We compared the clinical and electrophysiologic characteristics of 295 consecutive patients with the Wolff-Parkinson-White syndrome who underwent radiofrequency ablation of 311 manifest APs (group A) with those of 6 patients with the Wolff-Parkinson-White syndrome in whom a decrementally conducting AP was detected after an attempt at ablation. RESULTS: The AP ablation site in group B patients was at the coronary sinus ostium region in 3 patients, middle cardiac vein in 2 patients, and left posteroseptal region in 1 patient. Sixty-two bypass tracts in group A patients and all 6 in group B patients were ablated at these locations, while 249 bypass tracts in group A patients and none in group B patients were ablated elsewhere (P = .0001). Five of the 6 patients (83%) with acquired Mahaim physiology had an AP located in the venous system. The odds for developing an acquired decremental antegrade atrioventricular AP when it was located inside the venous system were 1 in 6. All group B decremental APs were sensitive to adenosine, but none in 85 group A patients (P <.0001). CONCLUSIONS: The risk for developing decremental conduction after the ablation of a rapidly conducting AP is greater for APs inside the coronary venous system. Acquired decremental antegrade atrioventricular APs are electrophysiologically similar to de novo ones. They are capable of being part of an arrhythmia circuit and, therefore, should be targeted for ablation.

Clinical, electrocardiographic, and electrophysiologic characteristics of patients with a fasciculoventricular pathway: the role of PRKAG2 mutation.

BACKGROUND: The ECG, clinical, and electrophysiologic profiles of patients with a fasciculoventricular pathway are well described. Fasciculoventricular pathways occurring in the setting of glycogen storage cardiomyopathy possess unique features. OBJECTIVE: The purpose of this study was to compare the clinical, ECG, and electrophysiologic characteristics of patients with a fasciculoventricular pathway, with or without glycogen storage cardiomyopathy. METHODS: Two groups of patients with a fasciculoventricular pathway were compared: group A consisted of 10 patients with the PRKAG2 mutation (Arg302gln), and group B consisted of 9 patients without the mutation. RESULTS: Thirty percent of group A patients had left ventricular hypertrophy, and none had an additional accessory pathway. Group B patients had no structural heart disease, and 33% had an additional accessory pathway. Group A patients had a slower resting heart rate (56 ± 7 vs 75 ± 10 bpm, P <0.0001), a wider QRS complex (0.15 ± 0.01 vs 0.11 ± 0.02 ms, P = .0004), and a longer HV interval (34 ± 1 vs 25 ± 3 ms, P = .0003). During long-term follow-up, 50% of group A patients developed complete AV block versus none in group B. Eighty percent of group A patients developed atrial flutter and/or atrial fibrillation. No Group B patient had any arrhythmia during follow-up after successful ablation of additional arrhythmia circuits. No sustained ventricular arrhythmia was induced in any patient from either group. CONCLUSION: Patients with a fasciculoventricular pathway associated with the PRKAG2 mutation have distinct clinical, ECG, and electrophysiologic profiles and should be correctly identified because of their ominous long-term prognosis. Patients without the mutation have an excellent arrhythmia-free prognosis after treatment of additional circuits.

The atrioventricular interval during pre-excited tachycardia: a simple way to distinguish between decrementally or rapidly conducting accessory pathways.

BACKGROUND: Recognition of the presence and role of decremental fibers during wide QRS tachycardia requires carefully executed intracardiac studies. OBJECTIVE: This study sought to determine the value of the atrioventricular (AV) conduction time during pre-excited tachycardia to differentiate a fast from a decrementally conducting accessory pathway (AP). METHODS: Fifty-one patients with 56 pre-excited tachycardias were included in the study: Group I: 27 patients with 31 antidromic tachycardia (ADT) using an atriofascicular pathway, Group II: 2 patients with pre-excited tachycardia due to bystander AV conduction, Group III: 3 patients with ADT and a short AV Mahaim fiber, and Group IV: 19 patients with 21 ADT using a fast conducting right-sided AP. The AV interval was measured in the His bundle electrogram and related to the tachycardia cycle length (TCL) by making an AV/TCL index. RESULTS: An AV interval > or = 150 ms during pre-excited tachycardia yielded a 91% sensitivity, 90% specificity, positive predictive value of 94%, and negative predictive value of 83% for AV conduction over a decrementally conducting pathway, whereas a > or =0.55 AV/TCL index yielded a sensitivity of 89%, specificity of 100%, positive predictive value of 100%, and negative predictive value of 84%. In 3 of 4 patients with Mahaim fibers and a <0.55 AV/TCL index, a prolonged ventriculoatrial (VA) conduction time was found. CONCLUSIONS: An AV interval > or =150 ms during pre-excited tachycardia is a fast and reliable method for detecting a decrementally conducting AP. Correcting the AV interval by the tachycardia cycle length improved specificity and positive predictive accuracy.

Reversible cardiomyopathy provoked by focal ventricular arrhythmia originating from the base of the posterior papillary muscle.

BACKGROUND: A new distinct clinical syndrome comprising of ventricular tachycardia or frequent premature beats arising from the base of the posterior papillary muscle has recently been reported. The cardiac arrhythmia had a non-reentrant mechanism and none of the patients had left ventricular dysfunction. CASE REPORT: We report on a 55-year-old female patient presenting with a dilated cardiomyopathy and frequent ventricular premature beats (VPB). Ventricular arrhythmia was refractory to amiodarone. Eighteen months after the onset of palpitations the patient evolved from NYHA functional class I to class III, with a LVEF of 38%. VPB comprised 26% of the total number of QRS complexes during 24 h Holter monitoring, which also recorded 12 salvos of non-sustained VT. NT-pro BNP level was 1,080 mcg/ml. During electrophysiologic study LV geometry was reconstructed with Ensite NAVX system which allowed voltage and activation mapping. We found neither scar-like nor low-voltage tissue in the endocardial surface of the LV. VPB was mapped in a site at the base of the posterior papillary muscle, which was confirmed by LV angiography. Cool-tip catheter ablation successfully eliminated VPB. Three months later, the patient was in NYHA functional class I, NT-proBNP level was 98 mcg/ml, with partial LV reverse remodeling and LVEF of 58%. Twenty-four hours Holter monitoring showed only 24 single premature beats. CONCLUSION: Focal ventricular arrhythmia arising from the base of the left posterior papillary muscle can provoke significant left ventricular dysfunction. Left ventricular dysfunction reversed after elimination of the VPB.

Prevalence of systemic hypertension in students aged 7 to 14 years in the municipality of Barbacena, in the State of Minas Gerais, in 1999.

OBJECTIVE: To detect the prevalence of systemic hypertension in children and to establish the relation between blood pressure levels and sex, age, ethnicity, weight, and height. METHODS: The prevalence of systemic hypertension and its relation to sex, age, ethnicity, weight, and height were studied in 611 students aged 7 to 14 years out of 19.928 students classified according to age, ethnicity, and sex, who underwent anthropometric evaluation and blood pressure measurement. Hypertensive individuals were considered those whose blood pressure level was > the 95th percentile for age and sex, confirmed on 3 examinations. RESULTS: The prevalence of hypertension was 16.6% in the first evaluation, and 4.6% and 2.5% in the subsequent evaluations. The mean blood pressure levels increased with age. Weight was important, not only to determine blood pressure in healthy children, but also to determine systemic hypertension in children, which was not observed with height despite the different studies. The prevalence of systemic hypertension in the different ethnic groups and the mean blood pressure levels according to sex were similar. CONCLUSION: In addition to routine physical examinations, age, weight, and appropriate cuff size should be considered when assessing blood pressure in children to prevent hypertension, morbidity and mortality, and to avoid placing a financial burden on health care providers.

Prevalência da hipertensäo arterial sistêmica em escolares de 7 a 14 anos do município de Barbacena, Minas Gerais, em 1999 / Prevalence of systemic hypertension in students aged 7 to 14 years in the municipality of Barbacena, in the State of Minas Gerais, in 1999

OBJECTIVE: To detect the prevalence of systemic hypertension in children and to establish the relation between blood pressure levels and sex, age, ethnicity, weight, and height. METHODS: The prevalence of systemic hypertension and its relation to sex, age, ethnicity, weight, and height were studied in 611 students aged 7 to 14 years out of 19.928 students classified according to age, ethnicity, and sex, who underwent anthropometric evaluation and blood pressure measurement. Hypertensive individuals were considered those whose blood pressure level was > the 95th percentile for age and sex, confirmed on 3 examinations. RESULTS: The prevalence of hypertension was 16.6 percent in the first evaluation, and 4.6 percent and 2.5 percent in the subsequent evaluations. The mean blood pressure levels increased with age. Weight was important, not only to determine blood pressure in healthy children, but also to determine systemic hypertension in children, which was not observed with height despite the different studies. The prevalence of systemic hypertension in the different ethnic groups and the mean blood pressure levels according to sex were similar. CONCLUSION: In addition to routine physical examinations, age, weight, and appropriate cuff size should be considered when assessing blood pressure in children to prevent hypertension, morbidity and mortality, and to avoid placing a financial burden on health care providers