These experiments were designed to determine if the location of ectopic ventricular stimulation influences ventricular performance. Heart block was produced in dogs by ligating the A-V bundle. Small bipolar electrodes were implanted in the apex, high lateral wall, and posterior septal region in six dogs. Several days after recovery dye dilution cardiac outputs, femoral arterial, and right atrial pressures were measured while stimulating from each of the three sites at varying rates between 60 and 240 beats/min. Mean cardiac outputs from stimulation at each of the three sites were similar and their 95% confidence intervals overlapped. Mean systemic pressure did not change significantly with frequency or location of ventricular stimulation. The experiments suggest that the pathway of ventricular activation does not affect ventricular function in complete heart block.

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We have presented the case of a 46‐year‐old woman who came to us with symptoms of superior vena caval obstruction caused by a metastatic leiomyosarcoma in the right antrium. The necessity of angiocardiography to establish the diagnosis of atrial tumors is stressed, as well as the complications that may ensue. The uterus was thought to be the source of the tumor.

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