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F J Bonte

Publications and source records attributed to F J Bonte.

At least 73 records · Page 4Linked to original sources
PubMed1980

A computer-based scintigraphic method for sizing acute inferior myocardial infarcts.

A modeling procedure, employing multiple 99mTc-PYP myocardial scintigrams, was applied to acute inferoposterior myocardial infarcts in 12 dogs. Four modeling schemes were developed, and the model volume predictions were correlated with morphometrically determined infarct masses. Correlation values ranged from r = 0.66 (p less than 0.02) to r = 0.80 (p less than 0.005), suggesting that the method may enable noninvasive quantitative sizing of acute inferoposterior myocardial infarcts.

Animals↗
PubMed1980

Modified technetium-99m heparin for the imaging of acute experimental myocardial infarcts.

We have reported previously that technetium-99m heparin (TcH) accumulates in, and allows scintigraphic identification of, damaged canine myocardium occurring with temporary occlusion and reperfusion of the left anterior descending (LAD) coronary artery. A recent modification consists of using heparin from sheep lung, with stannous phosphate as the reducing agent. In 12 dogs with permanent LAD occlusion, six were injected intravenously with TcH (3--6 mCi) at 24 hr after occlusion, and six at 48 hr. Each experimental animal demonstrated relatively high TcH uptake in the left-ventircular infarct region as compared with normal myocardium. The in vivo scintigrams in all animals with gross myocardial infarcts were positive. The results suggest that this modified TcH has value for identifying experimental myocardial infarcts and that the reduced bone uptake, compared with that occurring with Tc-99m phosphates, may be an advantage for scintigraphic infarct detection.

Animals↗
PubMed1979

ST isopotential precordial surface maps in patients with acute myocardial infarction.

ST amplitude distributions were studied in 41 patients with acute myocardial infarction by deriving isopotential maps from a 5 x 7 electrode precordial matrix. Independent data on infarct size and localization were obtained utilizing the technetium 99m stannous pyrophosphate scintigraphic method. The locus of maximal ST elevation was stable for at least two days in 86% of 27 patients with anterior infarction. A single maximum or maximum-minimum was found in 88% but 22% of the patients had multiple maxima and/or minima in at least two maps. Areas of significant ST elevation were often excluded from the precordial matrix. The site of maximal ST elevation correlated with scintigraphic infarct site but was displaced medially in lateral infarction. The relation between infarct size and sigmaST elevation was significant and curvilinear. sigmaST underestimated size in large anterior infarction. The correlation of the size and the number of sites with ST elevation greater than or equal to 1.5 mm was weak (r = 0.56). The degree of ST abnormality in 14 patients with inferior infarction decreased significantly during the initial 24 hours. The isopotential maps were similar to those obtained in anterior infarction but the polarity was reversed. The results provide limited support for the continued exploration of ST analysis as a clinical method but suggest that sizing methods should be based on total body surface mapping, taking into account the geometry and electrical properties of the torso.

Action Potentials↗
PubMed1979

Clinicopathologic findings in 52 patients studied by technetium-99m stannous pyrophosphate myocardial scintigraphy.

Scintigraphic, clinical and pathological findings were correlated in 52 patients studied by technetium-99m stannous pyrophosphate (99mTc-PYP) myocardial scintigraphy before death or surgical resection of myocardium. Fifty-nine clinical events were studied with scintigraphy in the 52 patients; 41 of the 59 were associated with one or more abnormal 99mTc-PYP studies and 18 with normal 99mTc-PYP scintigrams. Myocardial scintigrams were positive in 29 of 31 cases with clinicopathological evidence of a corresponding discrete, grossly obvious acute myocardial infarct, including 16 of 16 transmural myocardial infarcts and 13 of 15 subendocardial infarcts. In 16 of 18 cases, negative myocardial scintigrams correlated with the absence of acute myocardial infarction determined by clinicopathological evidence. In two cases small subendocardial infarcts (less than 3 g) were not detected by 99mTc-PYP myocardial scintigraphy. Of the 12 additional instances of positive 99mTc-PYP myocardial scintigrams, five were associated with clinical unstable angina pectoris and seven were in the category of persistently positive scintigrams, since the scans were obtained 2.5 months or longer after proven or suspected acute myocardial infarcts. In all 12 instances, the positive 99mTc-PYP scintigrams were associated with evidence of multifocal irreversible myocardial damage consisting of myocytolysis, coagulation necrosis and/or fibrosis, and the histological age of the lesions was compatible with acute injury corresponding to the time of scintigraphy. The findings indicate that a positive 99mTc-PYP myocardial scintigram is a sensitive indicator of significant myocardial injury which may occur as confluent coagulation necrosis corresponding to clinical acute myocardial infarction, or as multifocal coagulation necrosis or myocytolysis associated with unstable angina pectoris or recurrent ischemic heart disease, especially after previous infarctions.

Acute Disease↗
PubMed1978

Fatty acid accumulation and abnormal lipid deposition in peripheral and border zones of experimental myocardial infarcts.

Twenty-eight dogs with acute anterior myocardial infarcts due to proximal occlusion of the left anterior descending coronary artery (LAD) were studied at various periods following the occlusion to determine: (a) the time course and location of abnormal lipid accumulation after infarction, (b) the degree of muscle-cell injury associated with increased lipid deposition, and (c) whether uptake of fatty acid from the circulating fat pool contributes to lipid accumulation in certain myocardial regions. The findings show that myocardial lipid accumulation begins as early as 6 hr after proximal LAD occulsion. The increased lipid deposition occurs as nonmembrane-bound lipid droplets in muscle cells with and without ultrastructural evidence of irreversible injury. Analysis of tissue uptake of intravenoulsy injected [14C] oleic acid conjugated with albumin revealed relatively selective concentration of label in the peripheral and border regions of the infarct, but occasionally even the central subendocardial portion of the infarct concentrated the fatty acid. Thin-layer chromotography showed that most of the label was associated with the triglyceride fraction when the radiolabeled fatty acid was injected 6 or 24 hr after LAD occlusion. These myocardial cellular and topographical alterations will have to be considered when labeled fatty acids are used for imaging acute myocardial infarcts and/or if attempts are made to identify myocardial fat-laden cells scintigraphically.

Animals↗
PubMed1978

Technetium-labeled heparin: preliminary report of a new radiopharmaceutical with potential for imaging damaged coronary arteries and myocardium.

Heparin has been labeled with [99mTc] pertechnetate and its ability to image damaged coronary vessels and myocardium during and following myocardial ischemia has been studied in experimental animals. The data obtained indicate that Tc-99m heparin localizes in damaged myocardium and coronary vessels in canine models of temporary myocardial ischemia and reperfusion and in damaged myocardium during fixed coronary occlusion. Scintigraphic detection of damaged myocardium was possible in both models, but the highest levels of Tc-99m heparin in damaged myocardial tissue were found in those dogs with temporary coronary occlusion and reflow. The data suggest that Tc-99m heparin may be of value as a positive imaging agent when coronary arteries or myocardium are injured and either reperfusion is allowed and/or significant blood flow persists in the damaged area.

Animals↗
PubMed1977

Myocardial infarct imaging with technetium-99m phosphates.

Technetium-99m-phosphate imaging is particularly valuable in detecting (1) small transmural infarcts (3 g and larger in size); (2) new acute transmural infarcts in or near regions of old infarction; (3) acute subendocardial infarcts (larger than 3 g in size); (4) acute infarction in patients with left bundle branch block; and (5) perioperative myocardial infarction. Localization of inferior and posterior myocardial infarction is improved with imaging. Sizing of acute anterior and lateral infarcts has been accurately done in dogs and should prove helpful in patients. Extensive evaluation in both experimental animals and in patients has shown 99mTc-phosphate myocardial imaging to be a useful clinical tool, and it may be one of the most sensitive noninvasive ways presently available to identify acute myocardial necrosis. It is important to understand that 99mTc-phosphate imaging has a different pathophysiology basis from EKG's or serum enzymes. These tests do not compete but instead should complement one another.

Acute Disease↗
PubMed1977

Sizing acute myocardial infarcts: present limitations and potential approaches.

It is now possible by scintigraphic imaging to identify the presence of acute transmural or nontransmural myocardial infarcts by noninvasive techniques and to localize acute transmural infarcts. Radionuclide blood-pool scintigraphy allows assessment of the impact of old and new myocardial damage on left ventricular function.

Heart↗
PubMed1977

Infarct sizing with technetium-99m stannous pyrophosphate scintigraphy in dogs and man; relationship between scintigraphic and praecordial mapping estimates of infarct size in patients.

The present study was performed in order to evaluate the ability of technetium-99m stannous pyrophosphate (99mTc-PYP) myocardial scintigrams to size infarcts in experimental animals and man. In 10 dogs with proximal left anterior descending coronary artery occlusion and acute anterior myocardial infarcts, there was a significant correlation between scintigraphic infarct size and histological infarct weight (P less than 0.01). In 25 patients with acute anterior or anterolateral myocardial infarcts, there was a significant correlation between relatively large infarct size determined scintigraphically and the acute development of left ventricular failure. There was some overlap, however, in 99mTc-PYP scintigraphic infarct size between patients who did and did not develop left ventricular failure with infarction. Presumably this is explained by some patients having had earlier myocardial damage and thus developing left ventricular failure with relatively small new infarcts. There was also a statistically significant, but weak, correlation in patients between scintigraphic infarct size and precordial ST segment mapping including peak ST segment elevation (P less than 0.05) and the number of praecordial sites with ST segment elevation equal to or greater than 2 mm (P less than 0.01). The data suggest that 99mTc-PYP scintigrams and praecordial mapping measure some similar but some dissimilar aspects of infarct size in patients, and that 99mTc-PYP scintigraphy does size acute anterior and anterolateral infarcts in experimental animals and patients.

Animals↗
PubMed1977

Computed tomography: in vitro evaluation of myocardial infarction.

An in vitro study of computed tomographic (CT) scanning of experimental myocardial infarction (MI) was performed by studying isolated canine hearts 18 to 48 yrs. post-infarction. CT scanning does not detect histologically present calcification in the area of an MI, but can be used to identify wall thickness changes in these areas. Decreased attenuation coefficients are found infarcted myocardium where thinning is present. The potential CT scanning to detect areas of MI is confirmed.

Animals↗
PubMed1977

Positive 99mTc-stannous pyrophosphate myocardial image in a patient with carcinoma of the lung.

A "false-positive" 99mTc-stannous pyrophosphate (99mTc-PYP) myocardial image was seen in a patient with epidermoid carcinoma of the lung. The location of the increased activity corresponded to an area of direct invasion of the heart by carcinoma with associated multiple microscopic foci of myocardial necrosis. Metastatic carcinoma with myocardial necrosis should therefore be considered as a possible cause of a positive 99mTc-PYP myocardial image.

Aged↗