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Studies performed in 47 patients, 11 of whom underwent surgery for aneurysmectomy and 36 of whom underwent cardiac transplantation, were reviewed to assess the diagnostic accuracies of cross sectional echocardiography and cineangiography in detecting left ventricular mural thrombi and the effect of anticoagulation treatment on the incidence of such thrombi. Cross sectional echocardiography in 37 patients and cineangiography in 26 (16 patients were examined by both methods) were analysed independently by sets of two observers experienced in the respective methods. All four observers were blinded to the pathological or surgical findings regarding mural thrombus. Mural thrombus was confirmed by pathological investigation in 14 of 47 (30%) cases; 11 of these 14 patients had intra-aneurysmal thrombi. The negative predictive value was quite good for both methods, but cross sectional echocardiography had a superior positive predictive value. This was due both to detailed soft tissue resolution by cross sectional echocardiography and to overdetection of mural thrombi by cineangiography in cases of aneurysms without mural thrombi. Mural thrombi were present in three of 20 patients with preceding anticoagulation and in 10 of 19 patients without anticoagulation. The results emphasise that cross sectional echocardiography is more reliable than cineangiography in recognising thrombi. [ABSTRACT FROM PUBLISHER]

Imaging of coronary arteries using a venous instead of an arterial injection of contrast agent could provide a much safer method to diagnose heart disease. The tunability, intensity, and collimation of synchrotron radiation x-ray beams makes possible imaging systems with greatly improved imaging sensitivity. A pair of fan x-ray beams, a movable patient chair, and a multielement x-ray detector are used to acquire a pair of x-ray images above and below the iodine K edge. The logarithmic subtraction of these two images produces an image with excellent sensitivity to contrast agent and minimal sensitivity to bone and tissue. High-quality images from a dog and preliminary images from five humans have been obtained. Improvements are being -made to the system to increase the effective radiation flux and to measure the position of both x-ray beams. [ABSTRACT FROM AUTHOR]

To determine whether nitrous oxide (N2O) worsens myocardial ischemia by diminishing coronary pressure, we performed two sets of experiments using an acutely instrumented swine model of regional coronary ischemia. In constant pressure experiments (n = 11), coronary pressure and heart rate were kept constant as N2O (77%-79%) was substituted for N2 in the inspired gas. Nitrous oxide decreased systolic shortening, measured by sonomicrometry, from 68.0% to 63.6% (P less than 0.05) of preischemic control values in the ischemic zone and from 116.2% to 103.2% (P less than 0.05) of control values in the adjacent normal myocardium. There was no disproportionate effect of N2O on ischemic myocardium, and the N2O-induced depression of contractile function was fully reversible. In a series of constant external stenosis experiments (n = 13), the effects of N2O on heart rate, mean arterial pressure, and the coronary stenosis itself were not controlled. In these experiments, substitution of N2O for N2 induced deterioration in both the ischemic zone (systolic shortening decreased from 68.7% to 58.4% of preischemic control values, P less than 0.05) and in the adjacent normal myocardium (systolic shortening decreased from 113% to 102.9% of preischemic control, P less than 0.05). Nitrous-oxide-induced ischemic zone contractile dysfunction was often not reversible. The pressure gradient across the coronary stenosis did not increase and peripheral coronary pressure did not decrease because of N2O. Diffusion hypoxia was also excluded. This study confirms that N2O has a significant but mild depressant effect on the performance of both normal and ischemic myocardium.(ABSTRACT TRUNCATED AT 250 WORDS)

The low level of enzymatic activity of certain alpha 2-macroglobulin-proteinase complexes could be important to the function of factor VIII/von Willebrand glycoprotein since it is especially sensitive to proteolytic cleavage. To test this possibility, complexes of alpha 2-macroglobulin with plasmin, trypsin, and thrombin were formed in at least a 2:1 molar ratio of alpha 2-macroglobulin:proteinase and tested for effects on the factor VIII procoagulant activity of the factor VIII/von Willebrand glycoprotein. Neither the alpha 2-macroglobulin-trypsin complex nor the alpha 2-macroglobulin-plasmin complex affected factor VIII procoagulant activity. The behavior of the alpha 2-macroglobulin-thrombin complex was different. When alpha 2-macroglobulin and thrombin were incubated in a mole ratio of 3:1 or less, factor VIII procoagulant activity was enhanced to about the same extent as with free thrombin. Even at a 24:1 mole ratio, the mixture could produce 45% of the increase in factor VIII activity obtained with free thrombin. The isolated alpha 2-macroglobulin-thrombin complex could also activate the factor VIII procoagulant function to about 45% of the level obtained with an identical amount of uncomplexed thrombin. Analysis of the alpha 2-macroglobulin-125I-labeled thrombin complexes by rechromatography or by polyacrylamide gel electrophoresis in sodium dodecyl sulfate indicated that this activation was not due to free thrombin. We conclude that the alpha 2-macroglobulin-thrombin complex retains sufficient proteolytic activity to activate the procoagulant function of factor VIII/von Willebrand glycoprotein despite the latter being a very large substrate, having an estimated molecular weight of 1-20 million.

The application of coronary angiography is limited because it requires arterial invasion and the direct injection of contrast agent into the coronary arteries. A prototype system has been developed which achieves sufficient sensitivity to the iodinated contrast agent to allow the visualization of coronary arteries in dogs after its intravenous injection. The system uses two fan beams of x-rays from an electron storage ring and a 300 element linear silicon detector. Two interlaced images, spaced at 150 eV above and below the K absorption edge of iodine (33.2 keV), are acquired and the logarithmic subtraction of these two images produces an image which has maximal sensitivity to iodine and minimal sensitivity to soft tissue and bone. This approach appears suitable for studies on human subjects.