Noninvasive finding of local repolarization changes in the heart using dipole models and simplified torso geometry

Two inverse methods using dipole models for noninvasive assessment of local repolarization changes were investigated and compared in the simulation study. Lesions with changed repolarization were modeled by shortening of the action potential durations in ventricular regions typically influenced by occlusion of coronary arteries. Corresponding body surface potentials were computed using a multiple dipole model of the cardiac generator and an inhomogeneous torso model. Position of each lesion was then estimated by an inverse solution to a single dipole and to a group of five neighbouring dipoles. For both methods the lesion localization error was evaluated and its dependence on the lesion size and the noise in input data was studied. When no noise was present in the input data, the use of the inverse method to a group of dipoles instead of a single dipole resulted in an unsubstantial reduction of the mean localization error of small lesions from 0.6 to 0.5 cm. For medium and especially for large lesions the mean localization errors decreased significantly from 1.1 to 0.6 cm and from 2.3 to 1.0 cm, respectively. The inverse solution to a group of five dipoles was more sensitive to noise. However, for large lesions it still gave better results than the solution to a single dipole if the signal to noise ratio was higher than 30 dB.     

Smoking Cessation Programs for Seniors:A Group Model That Works

We describe an intensive group program for older adults, facilitated by a tobacco cessation specialist and a geriatric social worker, designed to focus on factors that maintain smoking behavior. Integral components dealt with issues specific to the older adult such as social isolation or economic need. Pharmacological therapy was provided. Participants with a mean age of 67 years who smoked an average of 19 cigarettes per day completed the program. Sixty-six percent of participants had been treated or were in treatment for depression and/or anxiety. Follow-up was completed at 1, 3, 6, and 12 months. The cessation rate across follow-up points was 68%. This program shows that older adults can maintain smoking cessation when provided with programs designed to address their issues.