Cardiothoracic ratio

The effect of dilation of the heart is to augment surface potentials. The potential is augmented by 82.3% when the radius of the heart is increased from 5 to 8 cm (the area occupied by the activation wavefront is proportionately increased as well). This theoretical prediction is opposite to the results of a clinical study (Ishikawa, 1971) of patients with congestive heart failure, which showed a decrease in potentials with increasing cardiothoracic ratio. The model simulations which permit the separation of interactive processes provide a possible explanation to this apparent discrepency. The congestive heart failure is accompanied by pulmonary edema, bringing about an increase in lung conductivity. As discussed above. 

Figure 2 Chest radiographs of the patient described in Figure 1 obtained on admission (left) and 14days after high-dose, parenteral thiamin treatment (right). On admission, the heart was grossly enlarged, extending downward and to the right, with a cardiothoracic ratio of 0.63. After treatment for 14 days, the cardiothoracic ratio was 0.44. (Modified from Anderson SH, Charles TJ and Nicol AD (1985) Thiamine deficiency at a district general hospital Report of five cases. Quarterly Journal of Medicine 55 15-32.)...

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