The Diagnosis of Thyrotoxicosis

Atrial fibrillation (AF) is the major arrhythmia seen in humans after 60 years of age. The role of identifying the foci inducing this arrhythmia is crucial because ablation techniques have gained importance in returning to sinus rhythm. Cardiovascular magnetic resonance imaging (MRI) has an important role in identifying theses foci. MRI studies were done using a Philips machine with a 1.5 Tesla magnet. The heart was evaluated with the following pulse sequence cardiac gated T-1 weighted coronal and cine G.R.E. horizontal long axis. This was followed by a gadolinium enhanced MRI angiogram. Emphasis was given to the junction of the right atrium and pulmonary veins, as well as the superior vena cava, inferior vena cava and left atrium. Measurements were done in patients (P) with intermittent chronic AF and normals. The data were analyzed statistically. We found statistically significant changes (p < .05) in the left superior pulmonary vein diameter in patients with intermittent and chronic AF and in right superior pulmonary vein diameter between intermittent AF and controls. Statistically significant changes (p < .05) were also seen in the inferior vena cava between controls and chronic AF and in the left superior pulmonary vein between controls and chronic AF. No changes were seen in the left atrium between chronic and intermittent AF. This shows the importance of MRI imaging in identifying the possible foci (dilatation of structures) of AF. This identification will reduce the average time required to convert AF to normal sinus rhythm.