Echocardiographic visualization of the anatomic causes of mitral regurgitation resulting from myocardial infarction

Carbon monoxide cardiotoxicity

Cardiac dysfunction including arrhythmias and myocardial ischemia have often been reported in carbon monoxide poisoning; scattered punctiform hemorrhages throughout the heart have been documented in autopsy samples. An appropriate diagnostic approach is crucial to assess carbon monoxide cardiac damage. This evaluation may be confounded by several factors, including the absence of overt symptoms and of specific ischemic changes in the electrocardiogram. In experimental studies, laboratory animals can develop cardiac changes similar to those seen in humans and therefore proved to be useful models to study the effects and the mechanisms of cardiac damage due to carbon monoxide. These investigations, as well as others performed in vitro, provide support for a direct action of carbon monoxide on the heart, in addition to systemic hypoxia produced by carboxyhemoglobin formation. This review focuses on the diagnostic aspects of carbon monoxide cardiotoxicity. Experimental results obtained in animals and in vitro models are also discussed.

Mitral regurgitation following first-time acute myocardial infarction--early and late findings by Doppler echocardiography

A total of 61 patients with first-time mild to moderate acute myocardial infarction and no reinfarction within the following 2 months were studied prospectively by Doppler echocardiography before hospital discharge and after 2 months to evaluate the prevalence of mitral regurgitation. Twenty-one age-matched healthy subjects served as controls. At baseline, the prevalence of Doppler-recorded mitral regurgitation was 74% and 29% in patients and controls, respectively. In the patients, the regurgitant flow measured by color flow Doppler was 1.04 cm2 (range 0.2-8 cm2) and occupied 7.5% (range 2-45%) of the left atrial area. Corresponding figures for controls were 0.35 cm2 (0.1-0.6) and 2.4% (0.7-4.5), respectively. On continuous wave Doppler, most patients (33/45) had Doppler signals similar to those of healthy controls. The prevalence of mitral regurgitation was about the same in anterior and inferior infarction (75 and 72% respectively). In the patients, the prevalence was similar after 2 months (79%) with minor changes in the Doppler characteristics of the regurgitation (regurgitant flow 1.12 cm2 and occupying 8.1% of left atrial area). The study demonstrates that in a group of patients with first-time mild to moderate myocardial infarction the prevalence of Doppler-recorded mitral regurgitation is high and mild in severity in the majority of the cases. The changes remain almost similar even after 2 months.

Pulsed Doppler echocardiographic analysis of mitral regurgitation after myocardial infarction

In 72 patients with previous myocardial infarction (MI), mitral regurgitation (MR) was assessed by pulsed-wave Doppler echocardiography and compared with physical and 2-dimensional echocardiographic findings. MR was found by Doppler in 29 of 42 patients (62%) with anterior MI, 11 of 30 (37%) with inferior MI (p less than 0.01) and in none of 20 normal control subjects. MR was more frequent in patients who underwent Doppler study 3 months after MI than in those who underwent Doppler at discharge (anterior MI = 83% vs 50%, p less than 0.01; inferior MI = 47% vs 27%, p = not significant). Of 15 patients who underwent Doppler studies both times, 3 (all with anterior MI) had MR only on the second study. Of the patients with Doppler MR, 12 of 27 (44%) with a left ventricular (LV) ejection fraction (EF) greater than 30% and 1 of 13 (8%) with an EF of 30% or less (p less than 0.01) had an MR systolic murmur. Mitral prolapse or eversion and papillary muscle fibrosis were infrequent in MI patients, whether or not Doppler MR was present. The degree of Doppler MR correlated with EF (r = -0.61), LV systolic volume (r = 0.47), and systolic and diastolic mitral anulus circumference (r = 0.52 and 0.51, respectively). Doppler MR was present in 24 of 28 patients (86%) with an EF of 40% or less and in 16 of 44 (36%) with EF more than 40% (p less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Hemodynamic abnormalities in acute myocardial infarction

Great strides have been made in the management of patients with acute myocardial infarction since the advent of coronary care units. However, congestive heart failure continues to be the major cause of in-hospital mortality. The accurate diagnosis and classification of hemodynamic abnormalities allow the application of specific therapies for each patient. Because clinicians can now routinely measure left and right ventricular preload, systemic and pulmonary vascular resistance, cardiac output, and arteriovenous oxygen difference, pharmacologic and surgical interventions can be applied in a scientific manner. In addition, mechanical complications can be promptly recognized and aggressively treated. Although the mortality rate for patients with severe left ventricular dysfunction after myocardial infarction remains high, expert management offers an improved prognosis for many patients.