Phase 2 reentry in man.

BACKGROUND: Ventricular extrasystoles are characterized by a fixed coupling interval to the last QRST complex preceding it. OBJECTIVES: We hypothesized that this QRST complex differed from QRST complexes of other sinus beats not followed by ventricular extrasystoles. Further, we investigated whether phase 2 reentry, demonstrated in animal experiments to initiate ventricular extrasystoles, ventricular tachycardia, and ventricular fibrillation, also plays a role in humans. METHODS: We examined 18 patients with ventricular extrasystoles and/or ventricular tachycardia by signal averaging of the ECG (group A) or by single-beat analysis of intracardiac electrograms (group B). Group A consisted of six patients without structural heart disease and one patient with the Brugada syndrome. Six of the seven patients had right ventricular outflow tract ventricular extrasystoles. Group B consisted of 11 patients undergoing radiofrequency ablation. Eight of the 11 patients had right ventricular outflow tract extrasystoles. RESULTS: In six of the seven patients in group A, we demonstrated significant ST-elevation and/or T-wave changes in the sinus beat preceding ventricular extrasystoles compared with the second last sinus beat in one or more of the three orthogonal leads X, Y, and Z. In 9 of the 11 patients in group B, single-beat analysis of unipolar and bipolar electrograms recorded close to successful ablation sites demonstrated similar changes, that is, ST-elevation (median peak voltage gradient 150 muV, range 0-1,700) and T-wave changes in the sinus beat prior to ventricular ectopy. In addition, J-point elevation was demonstrated in several cases. In total, significant changes were demonstrated in 15 of the 18 patients studied (83%). CONCLUSION: J-point elevation, ST-elevation, and T-wave changes documented in the last sinus beat prior to ventricular extrasystoles are in agreement with phase 2 reentry, suggesting that this may be the responsible mechanism for ventricular extrasystoles and ventricular tachycardia/fibrillation. The phenomenon has been demonstrated in only animal experiments to date.     

The global burden of periodontal disease: towards integration with chronic disease prevention and control

Chronic diseases are accelerating globally, advancing across all regions and pervading all socioeconomic classes. Unhealthy diet and poor nutrition, physical inactivity, tobacco use, excessive use of alcohol and psychosocial stress are the most important risk factors. Periodontal disease is a component of the global burden of chronic disease, and chronic disease and periodontal disease have the same essential risk factors. In addition, severe periodontal disease is related to poor oral hygiene and to poor general health (e.g. the presence of diabetes mellitus and other systemic diseases). The present report highlights the global burden of periodontal disease: the ultimate burden of periodontal disease (tooth loss), as well as signs of periodontal disease, are described from World Health Organization (WHO) epidemiological data. High prevalence rates of complete tooth loss are found in upper middle‐income countries, whereas the tooth‐loss rates, at the time of writing, are modest for low‐income countries. In high‐income countries somewhat lower rates for edentulism are found when compared with upper middle‐income countries. Around the world, social inequality in tooth loss is profound within countries. The Community Periodontal Index was introduced by the WHO in 1987 for countries to produce periodontal health profiles and to assist countries in the planning and evaluation of intervention programs. Globally, gingival bleeding is the most prevalent sign of disease, whereas the presence of deep periodontal pockets (≥6 mm) varies from 10% to 15% in adult populations. Intercountry and intracountry variations are found in the prevalence of periodontal disease, and these variations relate to socio‐environmental conditions, behavioral risk factors, general health status of people (e.g. diabetes and HIV status) and oral health systems. National public health initiatives for the control and prevention of periodontal disease should include oral health promotion and integrated disease‐prevention strategies based on common risk‐factor approaches. Capacity building of oral health systems must consider the establishment of a financially fair service in periodontal care. Health systems research is needed for the evaluation of population‐oriented oral health programs.     

Periodontal health through public health - the case for oral health promotion

Periodontal diseases are highly prevalent, particularly amongst socially disadvantaged populations, impact on quality of life and are costly to treat. Clinical treatments and chairside preventive approaches alone will never adequately address this problem. Indeed in many parts of the developing world clinical care and chairside prevention are both unaffordable and inappropriate for the control of periodontal diseases. A paradigm shift away from the individualized treatment approach to a population public health model is needed to promote periodontal health and, in particular to address social inequalities in periodontal status. Public health measures need to focus on the underlying determinants of periodontal diseases. Poor hygiene, tobacco use, psychosocial factors and related systemic diseases are the main risk factors for periodontal diseases. Public health interventions need to tackle these factors but also must recognize and act upon the distal underlying influences that determine and pattern these identified risks. Recognition also needs to be placed on the interlinking and common risk factors shared by periodontal diseases and other chronic conditions. A complementary range of public health policies acting at local, regional, national and international levels need to be implemented to achieve sustainable improvements in oral health. To be effective these policies need to link across the broader public health agenda and require public engagement and support. Clinicians, public health practitioners, commercial organizations and professional groups all have an important role to play in promoting periodontal health.