Faculty Bibliography

A 49-year-old woman with mitral and tricuspid mechanical valve prostheses developed marked weight gain with increasing abdominal girth and facial plethora 4 weeks after anticoagulation was temporarily interrupted for abdominal surgery. Transthoracic and transesophageal echocardiography documented severe tricuspid stenosis and regurgitation. The two discs of the tricuspid prosthesis were immobilized, half open and half closed. The prosthesis was replaced and the patient did well

A 37 year old man with recurrent episodes of endocarditis was found to have a large left coronary arteriovenous fistula communicating with the right atrium. The origin and termination of the fistula were identified using computed tomography and two-dimensional Doppler echocardiography. Coronary angiography confirmed the diagnosis and the patient underwent a successful operation

The change in contractility with increasing heart rate was studied in the left ventricle of dogs and in isolated trabeculae carneae of cats. For some of the studies in situ a transient isovolumic state was created by aortic occlusion. At physiological temperatures the frequency-force relationship is flatter than at room temperature and at the same temperature it is flatter in vivo than in vitro. The frequency-(dF/dt)max relationship is steeper than the frequency-force relationship at both temperatures in vivo and in vitro. The frequency-(dF/dt)max relationship is steeper in vitro than it is in situ, although the discrepancy is less marked than in the case of the frequency-force relationship. It is concluded that 'staircase' plays less of a physiological role in adjustment of contractile state in situ than might be inferred from studies of isolated tissue