sodium-pertechnetate-tc-99m and Atrial-Fibrillation

Atrial fibrillation (AF) and primary hypothyroidism are most often diagnosed in middle-aged and older dogs of large and giant breeds. We hypothesized that the frequency of primary hypothyroidism may be higher in dogs with AF than in those without AF. Two groups were investigated. Group 1 (March 1987-June 1990) consisted of 128 dogs with AF. A thyroid-stimulating hormone (TSH) stimulation test was performed in dogs with a low voltage on the ECG and low uptake of pertechnetate on a thyroid scan. Group 2 (July 1990-July 1991) consisted of both dogs with AF (n = 38) and control dogs (n = 235) in which plasma thyroxine (T4) was measured. If T4 was below 15 nmol/l, a TSH stimulation test was performed. The frequencies of primary hypothyroidism in group 1 (8/128) and in the group 2 AF dogs (3/38) were not different, but were higher than in the control animals (3/235) (P < 0.05). The group 1 and the group 2 AF dogs were found to be comparable, and pooling of the data of the two groups enhanced the significance of the frequency of primary hypothyroidism in dogs with AF versus the control animals (11/166 versus 3/235) (P < 0.01). We concluded that the frequency of primary hypothyroidism in dogs with AF is higher than in the group of control dogs without AF. This may be due to the additional cardiovascular changes accompanying primary hypothyroidism in dogs that already have heart disease.

Topics: Animals; Atrial Fibrillation; Cardiovascular Physiological Phenomena; Cardiovascular System; Dog Diseases; Dogs; Electrocardiography; Female; Hypothyroidism; Incidence; Male; Sodium Pertechnetate Tc 99m; Thyrotropin; Thyroxine

A new scintigraphic count-based method for measuring absolute left ventricular volumes is presented. It is a fast and simple technique that allows geometrical assumptions to be avoided and is free of radiation attenuation corrections. This method requires the acquisition of an image of the left ventricle in the right anterior oblique projection and the collection of gated blood pool images in the left anterior oblique projection. To assess the accuracy of the method scintigraphic stroke volumes were compared with those derived from thermodilution measurements during cardiac catheterization in 20 subjects, and to assess its precision the technique was applied to phantom data of known radionuclide volumes. Excellent correlations were found between the scintigraphic and both the thermodilution (r = .98) and phantom data (r = .99). The reproducibility (r = .97) of results was investigated by repeating data acquisition and analysis for 15 subjects on two different days, and the interobserver variability (r = .97) of the method was studied by having two computer operators calculate volumes for the same patient data for 20 randomly selected studies.

Topics: Adult; Aged; Atrial Fibrillation; Cardiac Catheterization; Cardiac Output; Cardiac Volume; Coronary Disease; Female; Heart Valve Diseases; Heart Ventricles; Humans; Male; Middle Aged; Radionuclide Imaging; Sodium Pertechnetate Tc 99m; Stroke Volume; Thermodilution