Moderate alcohol consumption the night before glycaemic index testing has no effect on glycaemic response.

A randomized crossover study was carried out to determine whether moderate alcohol consumption the night preceding glycaemic index testing has an effect on glycaemic response. Test foods consisted of two glucose beverages and two bread samples, containing 50 g of available carbohydrate. Each test food was consumed with and without alcohol the night preceding testing. Glucose concentration was measured over 2 h and area under the curve (AUC) determined. The AUC for bread and glucose without and with alcohol did not differ for either the glucose drink (ratio (95% confidence intervals): 1.00 (0.8, 1.1)) or bread (0.9; (0.8, 1.1)). Further, there was no difference in the glycaemic index (GI) of the bread with and without alcohol (64 (6) vs 67 (2)%; P=0.78). Moderate alcohol consumption the evening before GI testing does not affect glycaemic response or GI determination.

Corrosion behavior of a low modulus beta-Ti-45%Nb alloy for use in medical implants.

The corrosion and electrochemical behavior of a low stiffness beta -Ti-45wt.%Nb (Ti45Nb) was studied in solutions that resemble body environment, as compared to Ti6Al4V and Ti-55wt.%Ni (Ti55Ni, Nitinol) alloys currently used in surgical implants. In Ringers' solution, Ti45Nb alloy exhibited an excellent corrosion resistance, comparable to that of Ti6Al4V and much better than that of Nitinol. In acidic environments, beta -Ti45Nb remained passive under conditions where active dissolution was observed for both Ti6Al4V and Nitinol alloys. The results warrant further corrosion and biocompatibility studies of beta -Ti45Nb alloy to establish its suitability as implant material.

Echocardiographic detection of left main coronary artery obstruction.

Advances in two-dimensional echocardiography have improved the prospects of using this technique to detect left main coronary artery (LMCA) obstruction. Using an echocardiograph that had digital gray scale, a 3-MHz transducer and strobe freeze-frame capability and reviewing recordings on an off-line videotape-videodisc analyzer, we retrospectively examined the LMCA in 72 patients who underwent coronary cineangiography. Angiography showed 50% or greater LMCA obstruction in seven patients. All seven had high-intensity echoes in the walls of the LMCA. The high-intensity echoes were irregularly located in the artery and partially occluded it. The LMCA could frequently be recorded proximal and distal to the obstruction. A blinded observer reviewed 28 randomly selected patients from this group and correctly identified the four patients with LMCA obstruction. There was one true and two questionable false-positive diagnoses. In a prospective study of 31 patients, two independent observers correctly identified the three patients with LMCA obstruction. There were no false negatives, and one observer had one false positive. All of the false positives were in patients with proximal left anterior descending coronary artery obstructions. Echocardiography may be a practical means of identifying patients with the LMCA obstruction.

Reliability of two-dimensional echocardiography in assessing the severity of valvular aortic stenosis.

Two-dimensional echocardiographic studies have shown that maximum long-axis systolic aortic cusp separation (MACS) represents a useful, noninvasive method for estimating severity of valvular aortic stenosis in adults. Although mean values for patients with mild, moderate, and severe aortic stenosis have been clearly separated by this method, overlap occurs among individual patients. In this study, 81 adults with aortic stenosis were studied by two-dimensional echocardiography in the long-axis view. Long-axis assessment of aortic stenosis was obtainable in 93 percent of the patients. Less than 8-mm separation was 97 percent predictive of severe stenosis and 100 percent predictive of moderate or severe stenosis. Eight- to 12-mm had a low predictive value for the severity of stenosis. Greater than 12-mm separation was 96 percent predictive of mild aortic stenosis. Short-axis scans were attempted in 61 of the 81 subjects. Short axis assessment of aortic stenosis based on patterns of leaflet motion was obtainable in 46 of the 61 patients (73 percent) and provided a valuable index of severity. When short-axis scans were included in the assessment of severity in the subgroup of patients with 8- to 12-mm MACS, the predictive value improved greatly (86 percent vs 46 percent). Direct recording of aortic valve area in short-axis was successful in only 13 percent of the subjects. The echo aortic valve area compared with the hemodynamic calculated aortic valve area yielded an r = 0.87.

Incomplete mitral leaflet closure in patients with papillary muscle dysfunction.

Clinical acceptance of an association between papillary muscle dysfunction and mitral regurgitation is widespread, despite the lack of objective support. To evaluate a possible association, we performed echocardiographic examinations on 22 patients with prior myocardial infarction and clinical evidence of papillary muscle dysfunction, 40 patients with prior myocardial infarction and no clinical evidence of papillary muscle dysfunction, and 20 normal subjects. There was a unique pattern of incomplete mitral leaflet closure in a high percentage (91%) of infarct patients with mitral regurgitation. In these patients, one or both leaflets were effectively arrested within the cavity of the left ventricle during ventricular systole. Dyskinetic wall motion in the region immediately surrounding one of the papillary muscles was present in 23 of 24 patients (96%) with demonstrated incomplete closure. This study provides the first objective evidence that de novo mitral regurgitation in patients with prior myocardial infarction is due to dyskinesis involving the left ventricular myocardium beneath one of the papillary muscles, producing increased tension on the mitral leaflets and preventing normal closure.

Aneurysms of the posterior interventricular septum with postinfarction ventricular septal defect. Echocardiographic identification.

Using real-time, two-dimensional echocardiographic techniques, we recently studied six consecutive patients with acute myocardial infarction complicated by rupture of the posterior interventricular septum. Each patient experienced an inferior wall myocardial infarction, with a prior anteroseptal infarction in one. In each case, the clinical course was punctuated by the onset of heart failure and a low output state prior to, or coincident with, the appearance of a pansystolic murmur. During two-dimensional echocardiographic study, all six were found to have a discrete aneurysm of the posterior interventricular septum. Septal dyskinesis produced bulging of the interventricular septum far into the right ventricular cavity during systole. Our findings suggest that (1) septal dyskinesis and aneurysm formation may be a valuable sign in diagnosing ventricular septal performation; (2) the reported incidence of postinfarction septal aneurysm at surgery or autopsy may significantly underestimate its true frequency; and (3) septal dyskinesis must by considered as a contributing factor to the compromised hemodynamic status of patients with postinfarction ventricular septal rupture.

Possible detection of atherosclerotic coronary calcification by two-dimensional echocardiography.

Using two-dimensional echocardiography, a technique was developed for digitizing reflected acoustic signals and performing variable signal processing. This resulted in accentuation of differences in focal reflectivity of target tissues and improved ultrasonic tissue characterization. Study of a learning population of 200 patients demonstrated abnormal specular reflections from the proximal left coronary artery in patients with coronary artery disease. A prospective study of 100 patients was then performed to test the reliability of this method in predicting the presence of significant stenosis. Abnormal echocardiograms were a highly sensitive (94%) but less specific (65%) indicator of significant atherosclerosis of the left coronary symstem. One-third of patients had fluoroscopically identifiable coronary calcification, and 95% had abnormal echocardiograms. We postulate that our echocardiographic findings may be secondary to the presence of small amounts of coronary calcification. Echocardiographic tissue differentiation, therefore, may prove to be a noninvasive means of evaluating patients for coronary atherosclerosis.

Evaluation of left coronary artery anatomy in vitro by cross-sectional echocardiography.

This study was undertaken to provide a better anatomic description of the location and course of the left coronary artery within a commonly used ultrasonic tomographic plane. Twenty-three hearts were excised at autopsy and scanned in vitro. The locations of the left main (LMCA), left anterior descending (LAD), and left circumflex (LCCA) coronary arteries were confirmed by direct cannulation, by Cardio-Green injection, and by subsequent dissection. While the proximal LMCA was recorded in all specimens, the entire LMCA was visible in only 70%. Proximal portions of the LAD and LCCA were also identifiable in 70% of examinations, and their spatial positions were defined. In most recordings, the first branch of the LAD OR LCCA arose distal to the segment seen echocardiographically. The spatial orientation of the ultrasonic beam relative to the LAD and LCCA and the presence of other overlying cardiac structures limit the imaging of these vessels by cross-sectional echocardiography to only their most proximal portions.