The continuous challenge of AF ablation: From foci to rotational activity.

Pulmonary vein isolation (PVI) is central to ablation approaches for atrial fibrillation (AF), yet many patients still have arrhythmia recurrence after one or more procedures despite the latest technology for PVI. Ablation of rotational or focal sources for AF, which lie outside the pulmonary veins in many patients, is a practical approach that has been shown to improve success by many groups. Localized sources lie in atrial regions shown mechanistically to sustain AF in optical mapping and clinical studies of human AF, as well as computational and animal studies. Because they arise in localized atrial regions, AF sources may explain central paradoxes in clinical practice - such as how limited ablation in patient specific sites can terminate persistent AF yet extensive anatomical ablation at stereotypical locations, which should extinguish disordered waves, does not improve success in clinical trials. Ongoing studies may help to resolve many controversies in the field of rotational sources for AF. Studies now verify rotational activation by multiple mapping approaches in the same patients, at sites where ablation terminates persistent AF. However, these studies also show that certain mapping methods are less effective for detecting AF sources than others. It is also recognized that the success of AF source ablation is technique dependent. This review article provides a mechanistic and clinical rationale to ablate localized sources (rotational and focal), and describes successful techniques for their ablation as well as pitfalls to avoid. We hope that this review will serve as a platform for future improvements in the patient-tailored ablation for complex arrhythmias.

Recurrent Post-Ablation Paroxysmal Atrial Fibrillation Shares Substrates With Persistent Atrial Fibrillation : An 11-Center Study.

INTRODUCTION: The role of atrial fibrillation (AF) substrates is unclear in patients with paroxysmal AF (PAF) that recurs after pulmonary vein isolation (PVI). We hypothesized that patients with recurrent post-ablation (redo) PAF despite PVI have electrical substrates marked by rotors and focal sources, and structural substrates that resemble persistent AF more than patients with (de novo) PAF at first ablation. METHODS: In 175 patients at 11 centers, we compared AF substrates in both atria using 64 pole-basket catheters and phase mapping, and indices of anatomical remodeling between patients with de novo or redo PAF and first ablation for persistent AF. RESULTS: Sources were seen in all patients. More patients with de novo PAF (78.0%) had sources near PVs than patients with redo PAF (47.4%, p=0.005) or persistent AF (46.9%, p=0.001). The total number of sources per patient (p=0.444), and number of non-PV sources (p=0.701) were similar between groups, indicating that redo PAF patients had residual non-PV sources after elimination of PV sources by prior PVI. Structurally, left atrial size did not separate de novo from redo PAF (49.5±9.5 vs. 49.0±7.1mm, p=0.956) but was larger in patients with persistent AF (55.2±8.4mm, p=0.001). CONCLUSIONS: Patients with paroxysmal AF despite prior PVI show electrical substrates that resemble persistent AF more closely than patients with paroxysmal AF at first ablation. Notably, these subgroups of paroxysmal AF are indistinguishable by structural indices. These data motivate studies of trigger versus substrate mechanisms for patients with recurrent paroxysmal AF after PVI.

Prevalence of diagnosed diabetes in an urban area of Puducherry, India: Time for preventive action.

BACKGROUND: Epidemiological studies in India have shown that the prevalence of diabetes in the population is at least twice the number of persons diagnosed with diabetes residing in the given area. Similarly, community-based prevalence figures are unavailable in Puducherry,. AIMS: The aim of this study was to estimate the number of persons diagnosed with diabetes mellitus in Puducherry. SETTING AND DESIGN: This study was conducted in the service area of the Urban Health Centre (UHC), Pondicherry Institute of Medical Sciences (PIMS), Puducherry with retrospective data from family records. METHODS: The diagnosis of diabetes was retrospectively documented by reviewing all family folders of 2667 families (Population 11,835) for the period of 1/1/2003 to 31/12/2006. The data was verified by home visits from January until March, 2007. The case definition used, was a resident diagnosed with diabetes by a medical doctor and who was on antidiabetes treatment for at least the past six months. RESULTS: We found 643 individuals who had been diagnosed with diabetes. The prevalence of known diabetes was estimated to be 5.6% (5.31% in males and 6.1% in females). The age-sex specific prevalence was estimated using the 2001 Census data. There are about 48,876 known diabetics living in Puducherry. CONCLUSIONS: (1) Community-based health surveillance data comprise a useful tool to measure the prevalence of diagnosed cases of diabetes mellitus within the Indian context; 2) Diabetes mellitus is an important public health priority requiring urgent preventive action as there are about 97,752 persons in Puducherry who have either been diagnosed with diabetes or remain undiagnosed for the disease.

Diabetes prevalence and its risk factors in urban Pondicherry.

The present study was conducted in the Urban Health centre, Muthialpet, Pondicherry covering a population of 40000 from July to October 2007 by using a predesigned and pretested proforma to find out the risk of diabetes in general population by using Indian Diabetes Risk Score. A total of 616 respondents were studied comprising 325(53%) females and 290(47%) males. Majority 518(85%) were Hindus. Of them, 380 (62 %) had studied up to higher secondary and above, 539 (87%) belonged to upper middle and upper socioeconomic class. A large number of the subjects 422(68%) were above 35 years of age. Most of the respondents 558(90.50%) indulged in mild to moderate physical activity. Again, 422 (68.50%) had no family history of diabetes mellitus, 315 (51%) individuals were in the overweight category (>25 BMI), and 261 (83%) of high Diabetic Risk Score individuals were overweight. It is observed that chances of high diabetic score increase with the increase in BMI. Prevalence of diabetes in the studied population were 51 (8.27%), out of that 39 (76%) had high (>60) IDRS score. The relationship between BMI and IDRS shows that if BMI increases from under weight (<18.50) to obesity (>30) chances of risk for diabetes also increases significantly.