The contemporary management of acute myocardial infarction.

The contemporary management of acute myocardial infarction continues to evolve rapidly. The ultimate goal of therapy is timely, complete, and sustained myocardial reperfusion. There is a powerful time-dependent effect on mortality, and thus the balance between the time and likelihood of maximal reperfusion is crucial in deciding whether to use primary percutaneous balloon angioplasty or thrombolysis as the initial reperfusion strategy. Newer thrombolytic agents allow for equivalent coronary reperfusion compared with the standard accelerated alteplase (tPA) regimen with the advantage of easier dosing regimens. Low molecular weight heparin has been shown to be superior to unfractionated heparin and likely will be the standard of care in the near future. The use of glycoprotein IIb/IIIa inhibitors has been shown to decrease the short- and long-term complication rates in patients with acute coronary syndromes treated medically and with percutaneous coronary interventions; however, the choice of the optimal agent and dosing regimen in various clinical settings remains controversial. Combination therapy with low-dose fibrinolytics, glycoprotein IIb/IIIa inhibitors, and low molecular weight heparin, with or without subsequent early planned percutaneous coronary interventions, may provide the optimal strategy for maximal coronary reperfusion, but the results of large, randomized mortality trials currently underway need to be analyzed. Risk stratification will continue to play a major role in determining which patients should receive a specific therapy. The care of the patient with an acute myocardial infarction will continue to be a challenge requiring the proper selection from the vast pharmaceutic and interventional options available.

A real-time reconstruction system for magnetic resonance imaging.

A digital-electronic reconstruction system for MRI has been designed and demonstrated. The system is capable of reconstructing a 128 x 128 pixel image from complex-valued data in approximately 8 ms (122 frames per second) or a 256 x 256 pixel image in 32 ms (30 frames per second) using the standard 2D FFT reconstruction algorithm. Real-time MR imaging can be obtained when this reconstruction system is coupled with fast continuous echo-planar type data acquisition. This provides the unique potential for real-time monitoring of interventional procedures or for rapid patient positioning. The real-time reconstruction system presented here consists of four main subsystems: an analog to digital converter, an interface memory, the Fourier processor, and the display processor. The basic design of this reconstruction system is presented along with results, demonstrating the capability of the system.

A unique left-to-right shunt characterized by multimodality cardiac imaging.

We describe the first reported patient with a persistent left superior vena cava that communicates directly with the left atrium as an isolated congenital defect. She developed mitral stenosis and physiologic conditions that favored left-to-right shunting--a modified Lutembacher's syndrome. Noninvasive cardiac imaging completely elucidated her cardiac anatomy and physiology.

Risk stratification in unstable angina. Prospective validation of the Braunwald classification.

OBJECTIVES: To validate the Braunwald classification of unstable angina as a predictor of in-hospital cardiac complications; to determine which factors of the Braunwald classification contributed significantly to this prediction; and to devise a method of combining these predictive factors into an overall odds ratio for complications. DESIGN: A validation cohort of consecutive patients followed prospectively for in-hospital cardiac complications including myocardial infarction and death. SETTING: A community-based academic medical center. PATIENTS: A total of 393 patients admitted consecutively to the coronary care and intermediate care units with unstable angina. MAIN OUTCOME MEASURES: Major cardiac complications including death, myocardial infarction, congestive heart failure, cardiogenic shock, and severe ventricular dysrhythmias. RESULTS: Multiple logistic regression analysis identified four clinical factors used in the Braunwald classification that predicted the in-hospital occurrence of major cardiac complications: (1) myocardial infarction within less than 14 days (odds ratio [OR], 5.72; 95% confidence interval [CI], 1.92 to 16.97); (2) need for intravenous nitroglycerin (OR, 2.33; 95% CI, 1.31 to 4.17); (3) lack of beta-blocker or calcium channel blocker prior to admission (OR, 3.83; 95% CI, 1.55 to 9.42); and (4) baseline ST depression (OR, 2.81; 95% CI, 1.45 to 5.47). Two other clinical factors, diabetes and age, were also significant predictors. Validation of this model using parametric and nonparametric bootstrap techniques revealed excellent agreement between the CIs for adjusted ORs derived from the multiple logistic regression and those derived from the bootstrap. CONCLUSIONS: The classification of unstable angina proposed by Braunwald includes four factors that predict risk of major in-hospital cardiac complications. Specific factors used in this classification can be combined with diabetes and age to better stratify risk of major cardiac complications in this disorder using a simpler model.