Effects of exercise on transmitral gradient and pulmonary artery pressure in patients with mitral stenosis or a prosthetic mitral valve: a Doppler echocardiographic study.

Doppler echocardiography was used to determine changes in transmitral gradient and pulmonary artery pressure after exercise in 12 patients with mitral stenosis and 11 patients with a prosthetic mitral valve. The mean transmitral gradient in the mitral stenosis group was 9 +/- 7 mm Hg at rest and increased to 17 +/- 8 mm Hg after exercise. In patients with a prosthetic mitral valve, exercise resulted in an increase in mean transmitral gradient from 5 +/- 2 to 8 +/- 3 mm Hg. Calculated pulmonary artery systolic pressure increased with exercise from 41 +/- 19 to 70 +/- 32 mm Hg in the mitral stenosis group and from 28 +/- 8 to 39 +/- 15 mm Hg in patients with a prosthetic valve. Exercise Doppler echocardiographic evaluation of changes in transmitral gradient and pulmonary artery systolic pressure was found to be technically simple and an important addition to the noninvasive evaluation of patients with mitral valve disease.

Demonstration of viable, stunned myocardium with technetium-99m-sestamibi.

Delayed improvement of left ventricular contractile function in the setting of acute ischemia followed by reperfusion ("stunned myocardium") has been observed in a number of clinical scenarios, and may have important clinical implications. At present, there are no widely accepted techniques available to demonstrate its presence. We report a case in which a rest 99mTc-sestamibi scan performed 12 hr after thrombolytic therapy in the setting of acute myocardial infarction demonstrated viable myocardium in a region that was akinetic by contrast ventriculography. After surgical revascularization, follow-up 99mTc-sestamibi images showed normal perfusion and radionuclide ventriculography demonstrated normal left ventricular function. Demonstration of preserved 99mTc-sestamibi myocardial uptake in the infarct zone despite an extensive region of akinesis by contrast ventriculography predicted the recovery of left ventricular function after revascularization in this case. This suggests that perfusion imaging with 99mTc-sestamibi early after myocardial reperfusion can detect stunned myocardium and thus facilitate the decision-making process regarding management of such patients.

Digoxin for atrial fibrillation: a drug whose time has gone?

For over 200 years digitalis compounds have been used to treat atrial fibrillation. The rapid ventricular response to atrial fibrillation is frequently treated with digoxin to produce a controlled heart rate. Digoxin has also been proposed as a treatment for terminating recent-onset atrial fibrillation, for maintaining sinus rhythm after an episode of atrial fibrillation, and as prophylactic therapy in patients with paroxysmal atrial fibrillation to prevent excessive tachycardia during a paroxysm. Perhaps because it has been used for so long, few of these indications have been studied scientifically until recently. Studies now suggest that in patients with atrial fibrillation, digoxin is a poor drug for controlling heart rate during exertion, has little or no effect in terminating the arrhythmia, and may occasionally aggravate paroxysmal atrial fibrillation. Despite adequate digitalization, the heart rate at the onset of a paroxysm of fibrillation in patients receiving the drug does not differ from the heart rate in patients not receiving it. This article discusses the current role of digoxin in the management of patients with chronic, recent-onset, or paroxysmal atrial fibrillation.