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Biomedical subjects

D D Watson

Publications and source records attributed to D D Watson.

At least 91 records · Page 5Linked to original sources
PubMed1988

Left ventricular dysfunction in excess of the size of infarction: a possible management strategy.

In this report we describe two patients whose left ventricular dysfunction was far in excess of infarct size as evidenced by ECG changes and the magnitude of creatine kinase release. Both patients demonstrated redistribution in myocardial beds remote from the infarct zone on delayed rest thallium 201 images and both had multivessel disease evident on coronary angiography. Both patients experienced relief of symptoms and improvement in regional and global left ventricular function after revascularization surgery. The possible mechanisms of left ventricular dysfunction in myocardial beds remote from the zone of infarction are discussed.

Adult↗
PubMed1988

Acute myocardial infarction associated with single vessel coronary artery disease: an analysis of clinical outcome and the prognostic importance of vessel patency and residual ischemic myocardium.

The long-term outcome and the significance of residual ischemic myocardium, as assessed by predischarge exercise thallium scintigraphy and vessel patency, were studied in 97 patients with single vessel coronary artery disease by angiography 12 +/- 4 days after uncomplicated myocardial infarction. During a mean follow-up period of 39 +/- 17 months, no patients died, 6 (6%) had a recurrent nonfatal infarction and 25 (26%) experienced rapidly progressive angina requiring hospitalization. Although neither exercise-induced angina nor ST segment depression was predictive of a recurrent cardiac event, the mean number of infarct zone scan segments showing thallium redistribution (1.0 +/- 1.0 versus 0.5 +/- 0.8, p = 0.01) and the percent of patients with infarct zone redistribution (61 versus 39%, p = 0.05) were greater in those patients who experienced a late ischemic event. Kaplan-Meier analysis demonstrated a lower event-free survival rate in patients with redistribution (n = 45) than in those without redistribution (n = 52) (p = 0.019). Although no patient received immediate thrombolytic therapy, the infarct-related vessel was angiographically patent in 40 patients (41%). Vessel patency did not influence event-free survival, although a patent vessel, as compared with an occluded vessel, was associated with a greater prevalence of non-Q wave infarction (58 versus 21%, p less than 0.001), fewer persistent infarct zone thallium defects (1.2 +/- 1.1 versus 2.0 +/- 1.2, p = 0.001), more reversible infarct zone thallium defects (1.0 +/- 1.0 versus 0.5 +/- 0.9, p = 0.02) and a trend toward a higher left ventricular ejection fraction (53 +/- 10% versus 49 +/- 12%, p = 0.07). In summary, uncomplicated myocardial infarction in patients with single vessel coronary artery disease is associated with a very low incidence of subsequent death and reinfarction. The presence of infarct zone thallium redistribution, compared with its absence, is predictive of a higher cardiac event rate. These data should be considered when recommending prophylactic percutaneous transluminal angioplasty after uncomplicated myocardial infarction in asymptomatic patients with single vessel coronary disease. On the basis of these results, future randomized trials designed to evaluate the therapeutic efficacy of revascularization in asymptomatic postinfarction patients with single vessel disease should limit enrollment to those patients with residual ischemia located within the infarct zone.

Adult↗
PubMed1988

Success of internal mammary bypass grafting can be assessed intraoperatively using myocardial contrast echocardiography.

To determine whether the success of internal mammary artery bypass grafting can be assessed intraoperatively using myocardial contrast echocardiography, sonicated Renografin-76 was injected into the aortic root of 11 dogs during the delivery of cardioplegic solution. Studies were performed with the left anterior descending coronary artery patent and totally occluded, and after internal mammary artery bypass grafting distal to the occluded vessel. Flow rate during cardioplegia was constant for all three stages in each experiment. Myocardial contrast echocardiography clearly demonstrated homogeneous myocardial perfusion with the left anterior descending coronary artery patent, lack of perfusion in the left anterior descending artery bed during its occlusion and excellent perfusion of the occluded bed after internal mammary artery bypass grafting distal to the occlusion in 10 of the 11 dogs. In one dog, the bypass graft was technically inadequate and contrast opacification was not noted in the left anterior descending artery bed after internal mammary artery bypass grafting. The exponential function C(t) = Ae-alpha t + Be-beta t was fitted to computer-derived time-intensity curves from the myocardium, where alpha denotes contrast washout and beta denotes contrast appearance. Respective values for alpha and beta (mean + 1 SD) were similar for the patent left anterior descending coronary artery and after internal mammary artery bypass grafting distal to the occluded artery (0.11 +/- 0.10 versus 0.10 +/- 0.10, and 2.5 +/- 2.4 versus 1.1 +/- 0.56). In conclusion, myocardial contrast echocardiography has potential for intraoperative assessment of the adequacy of coronary artery bypass grafting.

Animals↗
PubMed1988

Myocardial contrast echocardiography in humans. II. Assessment of coronary blood flow reserve.

The hypothesis that myocardial contrast echocardiography could be used to simultaneously assess coronary blood flow reserve and the size of the perfusion bed supplied by a coronary artery was examined in nine patients and six dogs. All patients were undergoing cardiac catheterization and had single vessel coronary artery disease (greater than or equal to 85% stenosis of either the proximal left anterior descending or the left circumflex coronary artery); the six dogs had a critical stenosis of the left circumflex coronary artery. Three milliliters of sonicated Renografin-76 (mean microbubble size 6 micron) was injected into the left main coronary artery before and after intracoronary administration of papavarine, 6 to 9 mg. The beds supplied by the normal and stenotic vessels could not be differentiated during contrast echocardiography before injection of papavarine. However, after papavarine, the normal vascular bed showed significantly more contrast enhancement than did the bed supplied by the stenotic artery. This disparity in contrast enhancement made it possible to delineate the size of the bed perfused by the stenotic vessels. When quantitative analysis of the time-intensity curves obtained from the echocardiograms was performed in the dogs, the absolute values for the area under the curve, peak contrast intensity and curve width did not correlate with absolute blood flows measured with radiolabeled microspheres. However, the ratios of the areas under the curves derived from the two vascular beds before and after papavarine correlated well with the ratios of blood flows between the two beds during the same stages (r2 = 0.73 by linear regression and r2 = 0.85 by an exponential function). In comparison, the ratios of peak amplitudes and curve widths before and after papavarine had poor correlations with ratios of flows from the two beds (r2 = 0.18 and 0.02, respectively). In conclusion, myocardial contrast echocardiography can be used to simultaneously assess coronary blood flow reserve and the size of the perfusion bed supplied by a stenotic vessel.

Aged↗
PubMed1988

Prognostic utility of the exercise thallium-201 test in ambulatory patients with chest pain: comparison with cardiac catheterization.

The goal of this study was to determine the prognostic utility of the exercise thallium-201 stress test in ambulatory patients with chest pain who were also referred for cardiac catheterization. Accordingly, 4 to 8 year (mean +/- 1SD, 4.6 +/- 2.6 years) follow-up data were obtained for all but one of 383 patients who underwent both exercise thallium-201 stress testing and cardiac catheterization from 1978 to 1981. Eighty-three patients had a revascularization procedure performed within 3 months of testing and were excluded from analysis. Of the remaining 299 patients, 210 had no events and 89 had events (41 deaths, nine nonfatal myocardial infarctions, and 39 revascularization procedures greater than or equal to 3 months after testing). When all clinical, exercise, thallium-201, and catheterization variables were analyzed by Cox regression analysis, the number of diseased vessels (when defined as greater than or equal to 50% luminal diameter narrowing) was the single most important predictor of future cardiac events (chi 2 = 38.1) followed by the number of segments demonstrating redistribution on delayed thallium-201 images (chi 2 = 16.3), except in the case of nonfatal myocardial infarction, for which redistribution was the most important predictor of future events. When coronary artery disease was defined as 70% or greater luminal diameter narrowing, the number of diseased vessels significantly (p less than .01) lost its power to predict events (chi 2 = 14.5). Other variables found to independently predict future events included change in heart rate from rest to exercise (chi 2 = 13.0), ST segment depression on exercise (chi 2 = 13.0), occurrence of ventricular arrhythmias on exercise (chi 2 = 5.9), and beta-blocker therapy (chi 2 = 4.3). The exclusion of myocardial revascularization procedures as an event did not change the results significantly. Although the number of diseased vessels was the single most important determinant of future events, the exercise thallium-201 stress test when considered as a whole (which included the number of segments demonstrating redistribution on delayed thallium-201 images, change in heart rate from rest to exercise, ST segment depression on the electrocardiogram, and ventricular premature beats on exercise) was equally powerful (chi 2 = 41.6). Combination of both catheterization and exercise thallium-201 data was superior to either alone (chi 2 = 57.5) for determining future events. Exercise stress test alone (without thallium-201 data) was inferior to the exercise thallium-201 stress test or cardiac catheterization for predicting future events (chi 2 = 30.6).(ABSTRACT TRUNCATED AT 400 WORDS)

Cardiac Catheterization↗
PubMed1987

Prevalence of ischemia by quantitative thallium-201 scintigraphy in patients with ventricular tachycardia or fibrillation inducible by programmed stimulation.

The prevalence of exercise-induced ischemia was determined by thallium-201 (TI-201) scintigraphic criteria in patients with ventricular tachycardia (VT) or ventricular fibrillation (VF) inducible by programmed electrical stimulation. Thirty-eight patients (age 57 +/- 19 years), of whom 87% had angiographic coronary artery disease, underwent quantitative TI-201 exercise scintigraphy within 14 days of invasive electrophysiologic testing. The mean rest ejection fraction was 38 +/- 9%. Eighty percent of patients had 1 or more regions with akinetic or dyskinetic wall motion. Thallium-201 scan segments were scored as normal or containing redistribution defects or mild or severe persistent defects. Only 4 patients (10%) had only redistribution defects and 9 (24%) had both redistribution defects and persistent defects; 32 of 38 patients (84%) had 1 or more persistent defects, of which 26 had at least 1 severe, persistent defect (more than 50% reduction in TI-201 activity). Patients with and without exercise-induced VT had a similar prevalence of redistribution. Redistribution defect prevalence was similar in patients with polymorphic VT (3 of 13) and monomorphic VT (10 of 25) during programmed electrical stimulation (difference not significant). Thus, patients with VT or VF induced by programmed ventricular stimulation have extensive TI-201 scintigraphic abnormalities on exercise scintigrams, predominantly those suggesting scar, with associated severe regional wall motion abnormalities at rest. The scintigraphic prevalence of exercise-induced ischemia is low and TI-201 redistribution and exercise ST depression are observed with equal frequency in patients with and those without VT induced during exercise.

Adult↗
PubMed1987

Successful left ventricular opacification following peripheral venous injection of sonicated contrast agent: an experimental evaluation.

A new agent for use in contrast echocardiography that is capable of passing through the pulmonary circulation and opacifying the left ventricular cavity after intravenous injection was evaluated in a canine model. Air-filled albumin microbubbles were produced by sonication. A Coulter counter was used to size and count the resultant microbubbles in vitro. The microbubbles had diameters sufficiently small (less than 9 micron) to permit transpulmonary passage. A total of 72 injections were made into the forepaw vein of five closed-chest dogs. Simultaneous two-dimensional echocardiographic images of the right ventricle and the left ventricle were recorded and digitized on an off-line computer. Of the 72 injections, 59 (82%) were suitable for digitization. Forty of the 59 digitized injections (68%) demonstrated left ventricular contrast enhancement. Indicator-dilution curves were generated from plots of intraventricular gray level VS time, and the curve widths and areas under the curves were determined. The ratio of total indicator curve area for left to right ventricular cavity was 0.39 for the 40 successful injections, indicating transpulmonary transmission of 39% of the contrast effect. Injection of bubbles with mean size less than 6 microns resulted in a larger median left ventricular curve area than those with bubbles averaging from 6 to 9 microns. Injections demonstrating successful left ventricular contrast opacification had larger right ventricular curve areas than those that were not successful. Blood pressure, heart rate, and arterial blood gases were not significantly altered by repeated intravascular contrast injections. Postmortem examination of hearts, lungs, livers, and kidneys revealed no histologic changes.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1987

Acute non-Q wave myocardial infarction associated with early ST segment elevation: evidence for spontaneous coronary reperfusion and implications for thrombolytic trials.

The clinical significance of early ST segment elevation in patients with non-Q wave infarction is unknown. Therefore, 150 consecutive patients with creatine kinase isoenzyme-confirmed acute uncomplicated myocardial infarction who had ST segment elevation of 1 mm or more in at least two contiguous leads on the admission electrocardiogram were analyzed. None received thrombolytic therapy or acute coronary angioplasty. Predischarge angiography, radionuclide ventriculography and exercise thallium-201 scintigraphy were performed 10 +/- 3 days after myocardial infarction. Based on serial electrocardiograms (on days 1, 2, 3 and 10), all 150 infarcts were classified as Q wave (n = 115 [77%]) or non-Q wave (n = 35 [23%]). Although patients with Q wave infarction exhibited greater ST elevation, the amount observed in the non-Q wave group was appreciable, as reflected by the number of leads with ST elevation (3.8 +/- 1.8 versus 3.1 +/- 1.2, p = 0.007) and the sum of the ST elevation (9.6 +/- 7.4 versus 6.2 +/- 6.2 mm, p = 0.016). When compared with the Q wave group, patients with non-Q wave infarction had a shorter time to peak creatine kinase (23.0 +/- 9.1 versus 15.8 +/- 7.9 hours, p = 0.0001), a higher infarct vessel patency rate (24 versus 57%, p = 0.001), lower peak creatine kinase values based on 4 hour sampling (1,372 +/- 964 versus 664 +/- 924 IU/liter, p = 0.0002) and a higher left ventricular ejection fraction (46 +/- 12% versus 54 +/- 9%, p = 0.0003).(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1987

Myocardial thallium-201 kinetics and regional flow alterations with 3 hours of coronary occlusion and either rapid reperfusion through a totally patent vessel or slow reperfusion through a critical stenosis.

Myocardial thallium-201 kinetics and regional blood flow alterations were examined in a canine model using 3 hours of coronary occlusion and different methods of reperfusion. Group I comprised 10 dogs undergoing a 3 hour left anterior descending artery occlusion and no reperfusion. Group II comprised seven dogs undergoing 3 hours of left anterior descending artery occlusion and rapid reperfusion through a totally patent vessel. Group III comprised 10 dogs undergoing 3 hours of left anterior descending artery occlusion and slow reperfusion through a residual stenosis. All dogs received 1.5 mCi of thallium-201 after 40 minutes of coronary occlusion. During occlusion and 2 hours of reperfusion, serial hemodynamic, blood flow and myocardial thallium-201 activity measurements were made. The relative thallium-201 gradient (normal zone minus ischemic zone activity when initial normal activity is expressed as 100%) during left anterior descending coronary occlusion was similar in all groups. Group I, 87 +/- 3%; Group II, 78 +/- 6%; Group III, 83 +/- 6% (p = NS). After 2 hours of either method of reperfusion, the final relative gradient had decreased to a similar level (Group II, 51 +/- 9%; Group III, 42 +/- 6%). These values were not significantly different from the final relative thallium-201 gradient seen in dogs undergoing a sustained 3 hour occlusion (Group I, 55 +/- 5%). After 2 hours of reperfusion, both methods of reflow were associated with similar degrees of "no reflow." Transmural flows in the central ischemic zone were 89 +/- 10% of normal in Group II and 71 +/- 6% of normal in Group III after reperfusion, with both flows substantially higher than the relative thallium-201 activities in these dogs. Infarct size (percent of left ventricle) determined with triphenyltetrazolium chloride was similar in all groups (Group I, 24 +/- 4%; Group II, 29 +/- 4%; Group III, 25 +/- 4%). Thus, in this experimental canine model, 3 hours of coronary occlusion followed by either rapid reperfusion through a totally patent vessel or slow reperfusion through a critical stenosis resulted in little delayed thallium-201 redistribution or myocardial salvage as assessed histologically, despite significant recovery of regional flow.

Animals↗
PubMed1987

Exercise-induced ST segment elevation 2 weeks after uncomplicated myocardial infarction: contributing factors and prognostic significance.

To define the prevalence and clinical significance of exercise-induced ST segment elevation during predischarge treadmill testing after uncomplicated acute myocardial infarction confirmed by serum MB creatine kinase (CK) activity, 241 consecutive patients were prospectively investigated with quantitative exercise thallium-201 scintigraphy, rest radionuclide ventriculography and coronary angiography at 10 +/- 3 days. All patients received customary care, and in none was thrombolytic therapy or emergency coronary angioplasty employed. Eighty-two patients (34%) had exercise-induced ST segment elevation of greater than or equal to 1 mm above rest baseline. These patients were similar to the 159 patients without this finding with respect to history of prior infarction, the Norris coronary prognostic index, exercise duration, metabolic equivalents (METs) achieved and peak heart rate-blood pressure product. The frequency of inducible myocardial ischemia and extent of angiographic coronary disease was also comparable in the two groups. Findings associated with larger infarct size and transmural extent of infarction were more common in patients with exercise-induced ST segment elevation than in those without, including higher peak CK values (1,235 +/- 1,037 versus 942 +/- 915 mumol/min per liter, p less than 0.026), lower left ventricular ejection fraction (43 +/- 12 versus 51 +/- 10%, p less than 0.001), a higher prevalence of pathologic Q waves in greater than or equal to 2 contiguous infarct-related leads (80 versus 55%, p less than 0.001), more persistent thallium-201 defects (2.2 +/- 1.1 versus 1.4 +/- 1.1, p less than 0.001), abnormally increased lung uptake of thallium (33 versus 18%, p less than 0.01) and a greater number of akinetic or dyskinetic segments (3.2 +/- 2.5 versus 1.4 +/- 1.9, p less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Angiography↗
PubMed1987

Relationship between left ventricular systolic function and plasma clearance of 169Yb-DTPA in normal and ischemic dogs.

UNLABELLED: Plasma clearance of 169Yb-DTPA, a heavy chelate metal excreted only by glomerular filtration, was measured serially in a canine model to determine whether the clearance of this substance correlates with left ventricular systolic function. Fourteen anesthetized open-chest dogs were studied. Six dogs (group I) were used to estimate the clearance of 169Yb-DTPA in the setting of normal left ventricular function. Eight dogs (group II) were used to estimate clearance of 169Yb-DTPA in the presence of ischemic left ventricular dysfunction. Cardiac output, mean arterial pressure, and plasma levels of 169Yb-DTPA were measured serially. In group II dogs, area at risk for necrosis was defined using myocardial contrast echocardiography. The change in clearance of 169Yb-DTPA in group II dogs correlated well with change in cardiac output and area at risk (r = 0.80 and -0.93, respectively) and was significantly different from group I dogs (p less than 0.01). However, changes in clearance of 169Yb-DTPA in the group II dogs did not correlate well with change in mean arterial pressure (r = 0.26). IN CONCLUSION: (1) clearance of 169Yb-DTPA is constant over time in the absence of ischemic left ventricular dysfunction and derangement of other hemodynamic parameters; (2) changes in clearance of 169Yb-DTPA correlate well with changes in systolic pump function and left ventricular area at risk in the setting of ischemic left ventricular dysfunction, and (3) clearance of 169Yb-DTPA is not related to mean arterial pressure.

Animals↗
PubMed1987

Hypertrophic cardiomyopathy and myocardial ischemia with normal coronary arteries.

The case reported herein illustrates an unusual form of nonobstructive hypertrophic cardiomyopathy which was associated with Wolff-Parkinson-White syndrome, myocardial ischemia and necrosis despite normal coronary arteries. The patient is unique since the hypertrophied myocardial segment was localized exclusively to the posterolateral free wall. Quantitative thallium-201 scintigraphy demonstrated reversible ischemia that corresponded precisely with this region of posterolateral hypertrophy. While the exact mechanism for ischemia in patients with hypertrophic cardiomyopathy and normal coronary arteries remains controversial, a functional rather than anatomic disturbance of blood flow seems likely.

Adolescent↗
PubMed1986

Myocardial thallium-201 kinetics during coronary occlusion and reperfusion: influence of method of reflow and timing of thallium-201 administration.

Thallium-201 (201Tl) uptake and redistribution kinetics were examined in an open-chest canine preparation of occlusion and reperfusion. Seven dogs (group I) underwent 3 hr of sustained occlusion and received 1.5 mCi of 201Tl after 40 min of occlusion of the left anterior descending coronary artery (LAD). Group II (n = 18) underwent 60 min of LAD occlusion followed by sudden and total release of the ligature. Group IIa (n = 8) received intravenous 201Tl during occlusion of the LAD, whereas group IIb (n = 10) received intravenous 201Tl at the time of peak reflow. Group III dogs (n = 26) also underwent 60 min of LAD occlusion that was followed by gradual reflow through a residual critical stenosis. Animals in this group also received 201Tl either before (IIIa; n = 16) or after reflow was established (IIIb; n = 10). In group I, the relative 201Tl gradient (nonischemic minus ischemic activity) decreased from 88 +/- 8% (mean +/- SEM) to 59 +/- 6% during 3 hr of coronary occlusion (p = .034). After rapid and total reperfusion (group IIa), this gradient decreased from 71 +/- 6% during occlusion to 26 +/- 5% after reflow (p less than .001). After slow reperfusion through a residual stenosis (group IIIa), the gradient decreased from 81 +/- 5% to 31 +/- 5% (p less than .001) (p = .56 compared with group IIa). In rapidly reperfused dogs receiving intravenous thallium during peak reflow (IIb), initial 201Tl activity in the ischemic zone was 155 +/- 20% of initial normal activity and fell to 93 +/- 13% of normal after 2 hr of reperfusion. Similarly, in dogs reperfused slowly through a critical stenosis (IIIb), which received 201Tl during reflow, 201Tl activity soon after reflow was 94 +/- 4% of initial normal and decreased to 80 +/- 6% at 2 hr of reperfusion (p = .10). Histochemical evidence of necrosis was present in the biopsy region in 80% of the 20 dogs subjected to triphenyl tetrazolium chloride (TTC) staining. Microsphere-determined transmural blood flow was similar in all groups during LAD occlusion and final flows after 2 hr were comparable in all subgroups undergoing reflow. Ischemic zone flow (% normal) was significantly higher at the time of 201Tl administration in groups IIb (192 +/- 25%) and IIIb (110 +/- 5%), which received 201Tl during reflow, than in groups IIa (31 +/- 9%) and IIIa (22 +/- 5%), which received 201Tl during occlusion.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1986

The prevalence and clinical significance of residual myocardial ischemia 2 weeks after uncomplicated non-Q wave infarction: a prospective natural history study.

Despite having smaller infarct size and better left ventricular function, patients with non-Q wave myocardial infarction (NQMI) appear to have an unexpectedly high long-term mortality that is ultimately comparable to that of patients with Q-wave myocardial infarction (QMI). Patients with NQMI may lose their initial prognostic advantage because there is more viable tissue in the perfusion zone of the infarct-related vessel, rendering myocardium more prone to reinfarction. We tested this hypothesis in a prospective study of 241 consecutive patients 65 years of age or younger with acute uncomplicated myocardial infarction confirmed by creatine kinase levels (MB fraction). All patients received customary care and none underwent thrombolytic therapy or emergency angioplasty. Predischarge coronary angiography, radionuclide ventriculography, 24 hr Holter monitoring, and quantitative thallium-201 (201T1) scintigraphy during treadmill exercise were performed 10 +/- 3 days after infarction. Infarcts were designated as QMI (n = 154) or NQMI (n = 87) by accepted criteria applied to serial electrocardiograms obtained on days 1, 2, 3, and 10. The baseline Norris coronary prognostic index, angiographic jeopardy scores, and prevalence of Lown grade ventricular arrhythmias were similar between groups despite evidence for less necrosis with NQMI vs QMI, reflected by lower peak creatine kinase levels (520 vs 1334 IU/liter; p = .0001, 4 hr sampling), higher resting left ventricular ejection fraction (53% vs 46%; p = .0001), fewer akinetic or dyskinetic segments (1.2 vs 2.4; p = .0001), and fewer persistent 201Tl defects in the infarct zone (0.9 vs 1.9; p = .0001). Patients with NQMI also had more patent infarct-related vessels (54% vs 25%; p less than .0001) and a shorter time from onset of infarction to peak creatine kinase level (16.9 vs 22.5 hr; p = .0001). Importantly, the prevalence and extent of quantitatively determined 201Tl redistribution within the infarct zone on exercise scintigraphy was greater in patients with NQMI vs those with QMI (60% vs 36%, p = .007; and 0.98 vs 0.53 myocardial segments, p = .0003); when the two groups were stratified on the basis of the infarct-related vessel, subset analysis revealed the same findings. During 30 months median follow-up, cardiac mortality was low, 8.4% in the QMI group and 9.2% in the NQMI group (p = NS).(ABSTRACT TRUNCATED AT 400 WORDS)

Adult↗
PubMed1986

Evaluation of postoperative flow reserve in internal mammary artery bypass grafts.

The internal mammary artery has been advocated for use in bypass grafting owing to its superior long-term patency when compared to saphenous vein grafts. Concern exists that the flow through the internal mammary artery may be inadequate during periods of peak myocardial demand. This flow was investigated in 24 consecutive patients with a mean proximal left anterior descending artery stenosis of 87.5% who were selected for coronary bypass using the internal mammary artery. Within 8 weeks of operation, all were evaluated by exercise thallium 201 scintigraphy. Thallium activity, expressed as a ratio of anteroseptal activity to posterolateral wall activity (or inferior wall activity if the posterolateral wall was deemed abnormal), was 0.97 +/- 0.15. A second group of 25 patients, with normal coronary arteries, was similarly evaluated. The mean septal to posterolateral wall thallium activity ratio for these control patients was 1.0 +/- 0.15. A third group of 26 patients who underwent single-vessel percutaneous transluminal coronary angioplasty of the left anterior descending artery and a fourth group of 28 saphenous vein graft recipients were compared by stress thallium scintigraphy. Thallium 201 activity for the vein graft group (0.96 +/- 0.19) was not significantly different from that for the mammary artery group, whereas the flows obtained with a single attempt at angioplasty were significantly inferior (p less than 0.05). The internal mammary artery provides excellent coronary flow at peak myocardial demand and compares favorably to angioplasty and saphenous vein grafting.

Angioplasty, Balloon↗
PubMed1986

Significance of perfusion studies in the detection of transient myocardial ischemia.

In summary, myocardial thallium-201 imaging appears to be superior to exercise electrocardiography alone for detection of myocardial ischemia in patients with underlying coronary artery disease and chest pain. Risk stratification and prognostication can also be undertaken utilizing symptom limited stress scintigraphy in patients with stable chest pain syndromes or in conjunction with submaximal exercise thallium-201 scintigraphy after uncomplicated myocardial infarction. Patients with normal perfusion patterns or a single persistent defect have less likelihood of experiencing a subsequent cardiac event compared with patients with high risk scans demonstrating multiple defects in more than one vascular region or redistribution, or both. Thallium-201 imaging can be undertaken in the resting state in patients with unstable angina to detect "resting ischemia" or reversible vasospasm. Finally, the limitations of exercise or rest thallium-201 scintigraphy are discussed.

Angina Pectoris↗
PubMed1985

Prognosis with chest pain and normal thallium-201 exercise scintigrams.

The goal of this study was to determine the prognostic value of a normal exercise thallium-201 (TI-201) scintigram by quantitative criteria in a consecutive series of 349 patients with chest pain. Follow-up was obtained in 345 patients (99%) from 8 to 45 months (mean 34 +/- 7). Of these, 60% were men, 26% had typical angina, 21% had chest pain during exercise testing, 29% were unable to achieve 85% or more of maximal predicted heart rate, and in 9% ischemic ST depression (1.0 mm or greater) developed during exercise. At the time of exercise testing, 45% of patients were taking nitrates and 38% were receiving a beta-blocking drug. During the follow-up period, there were 5 cardiac deaths (0.51%/year), of which 2 were sudden, 6 patients had a nonfatal myocardial infarction (MI) (0.61%/year). Two of the 5 patients who died and 1 who had MI had angiographically normal coronary arteries. The event rate was significantly higher (p less than 0.01) in patients referred for early catheterization (5 of 53; 9%) compared with the rate for those not undergoing early angiography (6 of 298; 2%). However, the event rate was similar in those who underwent catheterization with angiographically normal coronary arteries and in those who had significant coronary artery disease.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗