Biomedical subjects
Publications and source records attributed to R T Palac.
Infections after cardiac transplantation are a frequent cause of early morbidity and mortality. An unusual site for such a complication is at the aortic anastomotic suture line. We report a case of an infected aortic pseudoaneurysm, seen as recurrent septicemia, during the first 6 months after cardiac transplantation.
To determine if early (4-h) thallium-201 imaging with ribose infusion would enhance detection of thallium redistribution better than late (24-h) imaging without ribose infusion, 15 patients with coronary artery disease underwent thallium stress tests by both methods within 2 weeks. All 15 patients had quantitative coronary angiography. After immediate postexercise planar imaging during the first of two exercise tests, patients were randomized to receive either intravenous ribose (3.3 mg/kg per min) or a control infusion of saline solution for 30 min. Images performed at 4 h for the ribose study were compared with those at 24 h for the saline control study. During the second test, exercise was carried to the same rate-pressure product and each patient received the opposite infusion. Four-hour postexercise images after ribose infusion identified 21 reversible defects not seen in the 24-h saline study. Three reversible defects were seen only in saline studies, but not with ribose at 4 h (p less than 0.01); 15 reversible defects were seen with both tests. When analyzed with respect to the 31 vascular territories supplied by a coronary artery with a greater than 50% stenosis, 8 territories had reversible defects present in the ribose but not the saline study and the saline study did not demonstrate reversible defects in territories that were seen in the ribose study (p less than 0.01). In 14 of these territories, reversible defects were seen with both tests. In 6 of 15 patients, additional vascular territories with reversible defects were identified after ribose infusion. It is concluded that ribose enhances the detection of thallium redistribution at 4 h compared with 24-h control images in patients with coronary artery disease and, therefore, substantially improves the identification of viable ischemic myocardium.
To investigate whether i.v. infusion of ribose, an adenine nucleotide precursor, postischemia facilitates thallium-201 (201Tl) redistribution and improves identification of ischemic myocardium in patients with coronary artery disease (CAD), 17 patients underwent two exercise 201Tl stress tests, performed 1-2 wk apart. After immediate postexercise planar imaging, patients received either i.v. ribose (3.3 mg/kg/min x 30 min) or saline as a control. Additional imaging was performed 1 and 4 hr postexercise. Reversible defects were identified by count-profile analysis. Significantly more (nearly twice as many) reversible 201Tl defects were identified on the post-ribose images compared to the post-saline (control) images at both 1 and 4 hr postexercise (p less than 0.001). Quantitative analyses of the coronary arteriogram was available in 13 patients and confirmed that the additional reversible defects were in myocardial regions supplied by stenosed arteries. We conclude that ribose appears to facilitate 201Tl redistribution in patients with CAD and enhances identification of ischemic myocardium.
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Repeat coronary angiography was performed in 42 patients 10 years after randomization to medical (n = 21) or surgical (n = 21) therapy for chronic angina. The native coronary arteries were classified into 15 angiographic segments and 3 arterial trunks for analysis of progression of coronary artery disease. The incidence rate of disease progression in coronary segments was 24% and 28% in medically and surgically treated patients, respectively (p = NS). Grafted segments showed a 38% rate of disease progression, which was higher than the 18% rate of for nongrafted segments (p less than 0.001) and the overall rate of 24% for medically treated patients (p less than 0.01). Similarly, 29 (94%) of 31 grafted arteries exhibited disease progression compared with 19 (59%) of 32 nongrafted arteries (p less than 0.01) and 42 (67%) of 63 arteries in medically treated patients (p less than 0.01). In grafted vessels, disease progression occurred more often in arteries proximal (84%) to the anastomosis than in arteries distal (16%) to graft insertion (p less than 0.001). Progression occurred in 46% of proximal segments compared with 23% of distal segments (p less than 0.02). Progression was seen in 23 (55%) of 43 segments with an occluded graft compared with 30 (31%) of 96 segments with a patent graft (p less than 0.02). Ten years after randomization, medically and surgically treated patients showed a comparable rate of disease progression in coronary segments. However, surgical therapy appeared to significantly accelerate atherosclerotic progression in the grafted vessels, especially in the proximal portions. Occluded grafts also correlated with an adverse effect on disease progression.(ABSTRACT TRUNCATED AT 250 WORDS)
It has been observed that atherosclerotic lesions (AL) concentrate certain porphyrins. We evaluated the usefulness of 111In-labelled Photofrin II (PFII), a porphyrin derived from haematoporphyrin derivative, for detection of experimental AL in cholesterol fed rabbits. Three groups of rabbits were studied: non-atherosclerotic (n = 3), 6 and 12 week cholesterol fed (n = 4, 3). 111In-PFII was injected intravenously and gamma camera images were obtained at 24 and 48 h. At 48 h, explanted aortas were also imaged. Aortic arch (AA) to background (BKG) count ratios were calculated from images of the whole body and explanted aortas. AA/BKG ratios were significantly higher in the 12 week cholesterol fed rabbits (3.9 +/- 0.72 at 24 h) and (4.0 +/- 0.67 at 48 h) than in the non-atherosclerotic rabbits (2.2 +/- 0.07 at 24 h) and (2.3 +/- 0.18 at 48 h) (p less than 0.05). The AA/BKG ratio for the explanted aortas showed similar results. Additionally, in two of three 12 week cholesterol fed rabbits, focal count deposition was visible on the whole animal images at the site of aortic arch atherosclerosis. We conclude that 111In-PFII concentrates in AL as early as 24 h after injection and has the potential to be used as an imaging agent for experimental atherosclerosis.
To determine if 201Tl plasma blood levels correlate with the presence of reversible myocardial defects during exercise testing, 14 patients with stable coronary artery disease underwent two separate exercise 201Tl stress tests. Between initial and delayed imaging, on one test the patients drank an instant breakfast drink (eating) and on the other they drank an equivalent volume of water as a control (H2O). Thallium-201 imaging was performed immediately postexercise, immediately after eating/H2O and 210 min after eating/H2O. Between initial and immediate post eating/H2O images 201Tl reversible defects occurred in 27/38 regions in the H2O test versus 15/38 regions in the eating test (p = 0.02). Over this early time period, plasma 201Tl activity was significantly higher in the H2O test than eating test (p less than 0.05). In conclusion, early reversal of 201Tl defects may, in part, be the result of higher plasma 201Tl activity early after initial postexercise 201Tl imaging.
Iodine-123 metaiodobenzylguanidine ([123I]MIBG) is a norepinephrine analog which can be used to image the sympathetic innervation of the heart. In this study, cardiac imaging with [123I]MIBG was performed in patients with idiopathic congestive cardiomyopathy and compared to normal controls. Initial uptake, half-time of tracer within the heart, and heart to lung ratios were all significantly reduced in patients compared to normals. Uptake in lungs, liver, salivary glands, and spleen was similar in controls and patients with cardiomyopathy indicating that decreased MIBG uptake was not a generalized abnormality in these patients. Iodine-123 MIBG imaging was also performed in cardiac transplant patients to determine cardiac nonneuronal uptake. Uptake in transplants was less than 10% of normals in the first 2 hr and nearly undetectable after 16 hr. The decreased uptake of MIBG suggests cardiac sympathetic nerve dysfunction while the rapid washout of MIBG from the heart suggests increased cardiac sympathetic nerve activity in idiopathic congestive cardiomyopathy.
Rapid volume expansion is a diagnostic procedure which can reveal typical hemodynamics of pericardial constriction in patients with pericardial disease who have normal hemodynamics in their baseline state. We studied 20 patients with previous coronary artery bypass surgery in order to determine whether this operation results in some degree of pericardial constriction which could be demonstrated by rapid volume expansion. After infusing 1 L of physiologic saline solution over six minutes, the right atrial pressure increased by 5 +/- 2 mm Hg, the right ventricular diastolic pressure by 4 +/- 3 mm Hg, the pulmonary capillary wedge pressure by 7 +/- 3 mm Hg, and the left ventricular diastolic pressure by 7 +/- 4 mm Hg (mean +/- SD). Equalization of the left and right cardiac pressures was not observed, and the normal respiratory variation of the pressures was not altered by rapid volume expansion. Thus, the pericardial manipulation associated with the performance of coronary artery bypass surgery does not commonly result in the development of subclinical pericardial constriction.
To determine whether eating a high-carbohydrate meal between initial and delayed postexercise thallium-201 (Tl-201) imaging affects detection of Tl-201 redistribution during exercise stress testing, 16 patients with stable angina performed 2 Tl-201 treadmill exercise stress tests within a 14-day interval. Immediately after initial postexercise imaging, patients either drank a commercially available instant breakfast preparation for the intervention test or drank an equivalent volume of water for the control test. Comparable exercise workloads were achieved by exercising patients to the same heart rate for both tests. The order of the 2 (intervention and control) tests were randomized. All patients had at least 1 region of Tl-201 myocardial redistribution on either their eating or control test scans, although only 7 of the 16 had positive treadmill exercise test responses. Forty-six regions showing Tl-201 myocardial redistribution were identified in all 144 regions examined. Significantly more of these regions were identified on control test scans than on eating test scans: 11 of 46 on both test scans, 6 of 46 only on eating test scans and 29 of 46 only on control scans (p less than 0.001). Consistent with results of the quantitative regional analysis, the percentage of Tl-201 clearance over 4 hours in the 46 Tl-201 myocardial redistribution regions was 39 +/- 8% for the eating tests and 29 +/- 8% for control tests (mean +/- standard deviation, p less than 0.003). In 4 patients diagnosis of transient ischemia would have been missed because their 14 Tl-201 myocardial redistribution regions were detected only on the control test scans.(ABSTRACT TRUNCATED AT 250 WORDS)
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Exercise thallium scintigraphy has proven to be a sensitive method for detecting coronary artery disease (CAD). However, early redistribution of thallium and inadequate exercise can reduce its sensitivity. In this study, dobutamine was infused in incremental doses (5, 10, 15, and 20 micrograms/kg/min) in 24 patients being evaluated for chest pain. Thallium scintigraphy was completed during the maximum dose of dobutamine tolerated and repeated 4 hours later. Significant CAD was present in 16 patients; the remaining eight had normal coronaries. Exercise ECG was obtained in 23 patients. During dobutamine thallium scintigraphy, reversible perfusion defects occurred in 15 of 16 CAD and in one of eight non-CAD patients, resulting in a sensitivity of 94% and a specificity of 87%. Exercise ECG had a sensitivity of 60% and a specificity of 63%. We conclude that: (1) dobutamine thallium scintigraphy appears to be a sensitive method for detecting significant CAD and provided a more sensitive screening test than exercise ECG; (2) dobutamine thallium scintigraphy is especially useful in patients who cannot exercise; and (3) because imaging occurs during dobutamine infusion, the problem of early redistribution may be mitigated.
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Factors related to late narrowing of aortocoronary vein grafts are poorly understood. Repeat aortocoronary bypass graft angiography was performed in 34 patients at 13 +/- 5 months and 61 +/- 13 months after surgery. In these patients, 61 of 65 grafts (94%) were patent at 1 year; at 5 years, 39 of these patent grafts (64%) remained unchanged, 21 (34%) had become progressively narrowed and one (2%) was totally occluded. There appeared to be no predilection for progression to occur at specific segments or in particular grafts: Eight of 28 left anterior descending (29%), seven of 17 right coronary artery (41%) and seven of 16 circumflex artery grafts (44%) (NS) showed further narrowing. Progressive graft narrowing occurred in 15 of 34 patients (44%). Risk factors (incidence of smoking, diabetes mellitus, hypertension, and triglyceride and cholesterol levels) in these 15 patients were compared with those in the 19 patients whose grafts were unchanged between 1 and 5 years. The incidence of smoking, diabetes mellitus (fasting blood sugar greater than or equal to 110 mg % or 2-hour postprandial sugar greater than or equal to 140 mg %) and hypertension (systolic blood pressure greater than 140 mm Hg or diastolic pressure greater than or equal to 95 mm Hg) were 46%, 27% and 33%, respectively, in the patients with progressive graft narrowing and 68%, 16%, 26% in the patients whose grafts were unchanged (NS). The average mean triglyceride levels were 617 +/- 785 mg % (+/- SD) and 195 +/- 86 mg %, respectively (p less than 0.05). The average mean cholesterol levels were 279 +/- 53 mg % and 234 +/- 35 mg %, respectively (p less than 0.01). In patients who have had aortocoronary bypass surgery, total graft occlusion is rare between 1 and 5 years after surgery. Progressive narrowing of grafts is common and appears to be associated with elevated blood lipids.
Immediate pacemaker malfunction following defibrillation or cardioversion has been reported. In this paper we report one patient whose pacemaker appeared to be functioning normally after D. C. countershock but malfunctioned 13 days later manifested by changing from an R-wave inhibited to an R-wave synchronous mode.
Repeat angiography was performed at 63 +/- 9 months in 26 medically treated patients and at 66 +/- 10 months in 32 surgically treated patients with chronic angina. The native coronary arteries were divided into three major trunk vessels and 15 angiographic segments. Progression of disease was defined as the appearance of new (greater than 50%) obstruction or significant worsening of existing lesions in a segment or vessel. The incidence of progression was similar in medical and surgical patients, comparing individual segments (69 of 312 [22%] and 91 of [23%], respectively) or vessels (49 of 78 [63%] and 60 of 96 [63%], respectively). In both medical and surgical patients, segments initially free of disease showed a 14% incidence of developing new lesions, compared with the 37% progression in segments initially diseased (p less than 0.001). In the surgical patients, progression occurred in 48 of 219 (22%) nongrafted and 43 of 177 (24%) grafted segments (NS). When analyzed by major trunk vessel, progression occurred in 40 of 57 grafted arteries (70%) and 20 of 39 nongrafted arteries (51%) (NS). The incidence of new total occlusions was similar in medical and surgical patients (6% and 8%, respectively); new total occlusions occurred predominantly in diseases segments (15% and 22%, respectively). In patients with stable angina pectoris who have medical or surgical treatment assigned by randomization, progression of coronary disease at 5 years is not influenced by which mode of therapy was received. Vessels initially free of disease are at relatively low risk for development of disease within 5 years. In surgical patients, grafted and nongrafted vessels show similar rates of progression.