Brugada electrocardiogram pattern "unmasked" by amiodarone infusion.

Brugada syndrome predisposes individuals to ventricular arrhythmias and sudden cardiac death, in the absence of structural heart disease. The typical Brugada electrocardiogram (ECG) phenotype is often concealed in affected population, and the existing genetic testing is capable of detecting just about 20% of cases. Therefore, the diagnosis largely requires various pharmacological provocative agents like class I antiarrhythmic drugs to unmask the unique features of Brugada ECG phenotype. We report an unusual case of "unmasking" of Brugada ECG pattern with ventricular tachycardia brought out by amiodarone infusion.

Retrograde buddy wire technique for coronary sinus lead placement--an approach to overcome coronary vein angulation.

Implantation of a left ventricular pacing lead via the coronary sinus to deliver cardiac resynchronization therapy has become standard therapy for patients with New York Heart Association (NYHA) Class III or IV heart failure and significant intraventricular conduction delay. Biventricular pacing has been shown to provide both symptomatic and mortality benefit in appropriately selected patients. There is significant variability in the anatomy of the coronary sinus and the epicardial coronary venous system. Although a suitable candidate vein may be identified during coronary venography, efforts toward successful guidewire placement or lead placement may be hampered by anatomic obstacles. In this case report, we provide a solution to overcome severe tortuosity encountered at the vein-coronary sinus junction and angulation of the proximal vein. The use of a second coronary sinus sheath and a retrogradely placed guidewire may overcome this anatomic obstacle of vessel tortuosity, when placement by other means has proven unsuccessful.

Risk Factors for the Development of Atrial Fibrillation in HIV Infected Patients.

Background: Patients with Human Immunodeficiency Virus (HIV) have an array of multi-organ involvement, including cardiovascular disease. CD4 count is one of the best parameters to monitor the severity of HIV disease. The arrythmogenic potential of HIV disease has not been well defined. The aim of the study is to establish whether an association between the severity of HIV and atrial fibrillation (AF) exists. Methods: Out of a retrospective cohort of 780 HIV patients from January 2006 to December 2008, 40 patients were selected that developed AF during this period .The age and sex matched controls (n=40) were selected for comparison. The comparison between both groups was done using Fischer Exact Test. Bivariate and multivariate analysis was also performed to analyze the results. Results: The data shows that 47%(19/40) of the patients with HIV who developed AF had CD4 count lower than 250 as compared to 20%(8/40) in the control group (P value = 0.017) Conclusion: The data supports the presence of a relationship between HIV and AF. Patients with lower CD4 counts are more susceptible to develop AF.

Viral load and CD4+ cell count as risk factors for prolonged QT interval in HIV-infected subjects: a cohort-nested case-control study in an outpatient population.

BACKGROUND: QTc interval prolongation is a serious ECG finding which has frequently been reported in HIV-infected patients, but associated risk factors have not been determined in this population. METHODS: Data were collected from the charts of a cohort of 135 consecutive HIV-infected patients from our HIV outpatient clinic. The cohort was divided into two groups, patients with prolonged QTc and those with normal QTc interval. Multiple variables and potential risk factors were analyzed, including the CD4+ cell count and viral load (VL), which were assessed on the same day or within several days of the initial ECG. RESULTS: 23 patients were found to have prolonged QTc (17%). No significant difference in baseline characteristics was observed between the groups; however, statistically significant differences were observed with regard to the CD4+ cell count and VL. CONCLUSION: A low CD4 cell count and a high VL may be risk factors potentially related to QT prolongation in HIV patients in the outpatient setting.

Sinus rhythm electrogram shape measurements are predictive of the origins and characteristics of multiple reentrant ventricular tachycardia morphologies.

INTRODUCTION: During clinical electrophysiologic study, multiple clinical tachycardia morphologies often can be induced in the infarct border zone, and all morphologies must be targeted for ablation therapy to be successful. Analysis of sinus rhythm electrogram shape for localizing figure-of-eight reentrant circuits in cases of multiple morphologies is proposed. METHODS AND RESULTS: Sinus rhythm activation maps were constructed from bipolar electrograms acquired at 196 to 312 sites in the epicardial border zone in 10 postinfarction canine hearts. In each heart, at least two distinct figure-of-eight reentrant ventricular tachycardia morphologies were inducible by premature electrical stimulation, as determined by activation maps of sustained tachycardias. Sinus rhythm maps were used to predict the location of the isthmus (central common pathway [CCP]), which is the protected region of the circuit bounded by arcs of block (mean accuracy 76.7 +/- 4%). Although reentrant circuits differed, the positions of the entrance point of each CCP were common. The location of the line that would span the CCP at its narrowest width also was estimated (mean accuracy 91.3 +/- 5%). Ablation at this line is expected to prevent reentry recurrence. In one test experiment, ablation prevented recurrence of both sustained reentrant tachycardia morphologies. CONCLUSION: Sinus rhythm electrogram analyses are useful for (1) localizing multiple reentrant circuits with differences in morphology that are inducible by premature stimulation in the infarct border zone, and (2) locating and orienting the position of a linear lesion for preventing recurrence of all morphologies with minimal damage to the heart.

Effects of pinacidil on electrophysiological properties of epicardial border zone of healing canine infarcts: possible effects of K(ATP) channel activation.

BACKGROUND: K(ATP) channels, activated by ischemia, participate in the arrhythmogenic response to acute coronary occlusion. The function of these channels in border zones of healing infarcts, where arrhythmias also arise, has not been investigated. Do these channels remain maximally activated during infarct healing, or do they downregulate after a period of time? Both might preclude further activation. METHODS AND RESULTS: Myocardial infarction was produced in dogs by ligation of the left anterior descending coronary artery. Impulse propagation in the epicardial border zone (EBZ) of 4-day-old healing infarcts was mapped during administration of pinacidil, a K(ATP) channel activator, directly into the EBZ coronary blood supply. Pinacidil restored conduction and excitability when the EBZ was initially inexcitable and had large regions of block (6 of 8 experiments). This allowed reentrant circuits to form in the EBZ, causing tachycardia (4 of 8 experiments). In hearts with an initially excitable EBZ, pinacidil shortened the effective refractory period and abolished conduction block at short cycle lengths (7 experiments). This effect prevented initiation of reentry (1 of 2 experiments). CONCLUSIONS: The response to pinacidil indicates that K(ATP) channels in the EBZ remain functional and can be activated to influence electrophysiological properties and arrhythmogenesis.