Comparison of two-dimensional echocardiography with gated radionuclide ventriculography in the evaluation of global and regional left ventricular function in acute myocardial infarction.

Two-dimensional echocardiography and gated radionuclide ventriculography were performed in 93 patients (66 men, 27 women; mean age 61 years) with 95 episodes of acute myocardial infarction within 48 hours and at 10 days after infarction. Electrocardiographic sites of infarction were: 35 anterior, 49 inferoposterior and 11 nonlocalized. Abnormal motion of the anterior wall, septum or apex was seen in 97 and 100% of anterior infarctions by radionuclide ventriculography and echocardiography, respectively. Abnormal motion of an inferior or posterior wall segment was seen in 91% of inferoposterior infarctions by echocardiography versus 61% seen by radionuclide ventriculography. Ejection fractions determined by echocardiography and radionuclide ventriculography correlated well (r = 0.82) and did not change from the first 48 hours to 10 days after infarction (0.48 +/- 0.14). Similarly, wall motion score showed minimal change from the first 48 hours to 10 days. In-hospital mortality was 37 and 42% in patients with an ejection fraction of 0.35 or less by echocardiography and radionuclide ventriculography, respectively. No mortality was seen in patients with an ejection fraction above 0.40 by either test. The echocardiographic wall motion score was also predictive of mortality (40 versus 2%; score less than or equal to 0.50 versus greater than 0.50). The 1 year mortality rate in the 81 short-term survivors was 17%. Mortality was lowest in patients with an ejection fraction above 0.49 or wall motion score above (0.79 (2 to 5%) and worse in those with an ejection fraction below 0.36 or wall motion score below 0.51 (36 to 63%) by either technique. Thus in acute myocardial infarction, echocardiography and radionuclide ventriculography provide a comparable assessment of left ventricular function and wall motion in anterior infarction. Echocardiography appears more sensitive in detecting inferoposterior wall motion abnormalities. Both techniques are capable of identifying subgroups of patients with a high risk of death during the acute event and with an equally high mortality rate over a 1 year follow-up period.

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.

Validation of left ventricular volume measurements by radionuclide angiography.

A nongeometric, attenuation-corrected technique to quantitate left ventricular volumes using equilibrium radionuclide angiography was validated in vitro and in vivo. In vitro experiments were performed to derive a linear attenuation coefficient, which was then employed in the volume determinations using balloons in a water bath. Good in vitro correlation was found between radionuclide and actual volumes (r = 0.99, p less than 0.0001), over a wide range (5 to 400 ml). In vivo validation was done by comparing the nuclear technique to contrast angiography in 29 patients: Good correlations were found for end-diastolic volume (r = 0.98), end-systolic volume (r = 0.95), stroke volume (r = 0.96), and ejection fraction (r = 0.85). When the conventional linear attenuation coefficient was used, the radionuclide technique consistently overestimated volumes in vitro and in vivo. Although high intraobserver and interobserver correlation coefficients were found (r from 0.88 to 0.93), significant individual variability existed, particularly in the interobserver data. Our data provide unique validation of radionuclide volume determinations, using an experimentally determined attenuation coefficient, which results in improved accuracy.

Comparison of different noninvasive methods of infarct sizing during experimental myocardial infarction.

This study evaluated the accuracy of several noninvasive infarct-sizing techniques in 12 awake, unsedated dogs with multivessel coronary obstructions and acute anterior myocardial infarcts. Estimations of infarct size by scintigraphy with technetium-99m Sn pyrophosphate (Tc-PP), serum creatine phosphokinase (CPK) release, peak serum myoglobin levels by radioimmunoassay, and precordial ECG mapping were compared and correlated with histologic measurements of infarct size. The comparisons indicate that precordial ST segments mapping, serum CPK release measurements and peak serum CPK, peak serum myoglobin, and Tc-PPi myocardial scintigraphy all provide approximate estimates of infarct size in this model. Each technique also has certain important limitations, however, including: (A) precordial mapping is relatively insensitive in the identification of small anterior infarcts, (B) serial serum CPK release measurements when obtained for only 24 hr after infarction tend to underestimate large anterior infarct size, and (C) Tc-PPi myocardial scintigrams may fail to recognize anterior infarcts less than 3 gm in size and may overestimate the size of small predominantly subendocardial infarcts. The findings also show that the closest estimate of histologic infarct size in this model was provided by combining two of the noninvasive techniques (precordial mapping to identify sites with 2 or more millimeters of ST segments elevation and Tc-PPi myocardial scintigrams) rather than by relying exclusively on any one technique alone.

A gamma camera for medical applications, using a multiwire proportional counter.

A multiwire proportional counter gamma camera, specifically designed for nuclear medicine applications, is portable and weighs less than 50 lb including shielding and collimator. The basic operating characteristics have been investigated with various radioactive sealed sources. The camera demonstrates a peak count rate of 850,000 cps, an intrinsic spatial resolution of 2.5 mm, and excellent image uniformity when used with x-ray sources in the range of 22-81 keV. Tests of the device with Ta-178--a very promising, short half-life (9.3 min), low-energy radionuclide--using 20 mCi injections provided images of quality comparable to those obtained from 15 mCi Tc-99m studies with conventional imaging devices. The camera used with Ta-178 offers particular promise in first-pass nuclear cardiology studies. Considerably improved study quality will likely result in this area because of the increased injectable dose levels offered by Ta-178 combined with the high-count rate capability and improved resolution.

Unstable angina pectoris: a randomized study of patients treated medically and surgically.

Fifty patients with the clinical syndrome of unstable angina pectoris were evaluated. Twenty-seven were randomized into medical or surgical treatment groups and subsequently followed up. The results of the study reveal that: (1) there is approximately a 16 percent incidence rate of significant left main coronary artery disease in patients with this entity at our institution; (2) 10 percent of patients do not have angiographically significant coronary artery disease; (3) pain relief is better in the surgically treated patients, but the 1 1/2 year survival rate is not significantly different between the groups; (4) 50 percent of the medically treated patients again had the syndrome of unstable angina pectoris in the initial few months of the follow-up period; (5) the operative and late postoperative mortality rate in patients presenting with unstable angina pectoris and left main coronary artery disease in this small group of patients was 43 percent; and (6) four of six patients with this syndrome whose condition was deemed inoperable and who were not randomized died within the subsequent few months.

EPA in the prevention of restenosis post PTCA.

The effect of fish oil on restenosis was evaluated in patients undergoing coronary balloon angioplasty. In addition to routine pharmacotherapy, subjects were given 2.8 g of eicosapentanoic acid (EPA) daily. Treatment was started within twenty-four hours after successful percutaneous transluminal coronary angioplasty (PTCA). After six months of therapy, participants were subjected to coronary arteriography, exercise scintigraphy, exercise electrocardiography, or clinical evaluation. Follow-up evaluation involved 97 coronary lesions in 85 patients. Partial or significant restenosis occurred in 36.5% of patients and 33% of vessels. The presence of severe stenosis before PTCA, dissection, thrombus, multilesion PTCA, and template bleeding time values were not correlated with restenosis. Dilation of the left anterior descending (LAD) and a residual stenosis greater than or equal to 35% were associated with restenosis. Approximately 20% of the patients related difficulty in taking the fish oil. Furthermore, these results show no advantage over expected restenosis rates.

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.

Effects of transluminal coronary angioplasty on left ventricular systolic and diastolic function at rest and during exercise.

The left ventricular global and regional systolic function, ventricular volumes, and peak diastolic filling rate (PDFR) were studied in 30 patients with coronary artery disease, before and 2 to 5 days after transluminal coronary angioplasty (PTCA), utilizing equilibrium radionuclide angiography at rest and during exercise. At rest, the global ejection fraction (EF) was unchanged before (60 +/- 9%) and after PTCA (62 +/- 10%). During exercise, global EF increased from 59 +/- 11% pre PTCA to 67 +/- 10 post PTCA (p less than 0.001). Twenty-two patients had abnormal EF response to exercise pre PTCA, versus seven post PTCA (p less than 0.001). Improvements in exercise regional EF paralleled the changes in global EF. End-systolic volume was unchanged at rest but decreased significantly with exercise post PTCA (60 +/- 36 ml pre vs 49 +/- 32 ml post PTCA, p less than 0.01). At rest, the PDFR was unchanged post PTCA (2.4 +/- 0.9 end-diastolic volume (EDV)/sec pre vs 2.5 +/- 0.8 EDV/sec post). During exercise, PDFR increased from 2.1 +/- 0.7 EDV/sec pre PTCA to 2.5 +/- 0.7 EDV/sec post PTCA (p less than 0.02). In conclusion, in patients with coronary artery disease, successful PTCA improves global and regional systolic function during exercise. Diastolic function is improved during exercise, a fact not previously demonstrated.

Detection of coronary artery disease with exercise two-dimensional echocardiography. Description of a clinically applicable method and comparison with radionuclide ventriculography.

Two-dimensional echocardiography (2-D echo) was performed in 73 patients evaluated for coronary artery disease (CAD) and in four normal volunteers before and immediately after a maximal treadmill exercise test. Diagnostic images were obtained from the apical and parasternal windows. In 17 patients with normal coronary arteriograms, ejection fraction (EF) increased from 66 +/- 9% (+/- SD) at rest to 73 +/- 8% after exercise (p less than 0.001), while in 56 patients with proved CAD, EF fell from 56 +/- 13% at rest to 53 +/- 16% after exercise (p less than 0.01). The sensitivity of postexercise 2-D echo for detecting CAD (based on abnormal EF response and/or regional dyssynergy) was 91% (51 of 56 patients) and the specificity was 88% (15 of 17). Sensitivity for one-, two- and three-vessel disease was 64% (seven of 11), 95% (20 of 21) and 100%, respectively. Patients with multivessel disease showed a significant fall in a wall motion score index, from 0.79 +/- 0.25 to 0.63 +/- 0.26. Exercise radionuclide ventriculography (RNV) was also performed in 41 of the subjects (17 normals and 24 CAD patients) on a bicycle ergometer. The overall sensitivity of 2-D echo in this subgroup was 92%, compared with 71% for RNV. The sensitivity of 2-D echo for one-vessel disease (n = 4) was 50%, that for two-vessel disease (n = 12) was 100% and that for three-vessel disease (n = 12) was 100%. Respective values for RNV were 0%, 80% and 90%. The specificity of 2-D echo was 88% and that of RNV was 82%. A significantly higher peak heart rate response was observed on the treadmill than on the bicycle ergometer in both CAD patients and normal subjects. We conclude that postexercise 2-D echo is a clinically applicable technique for the diagnosis and evaluation of CAD patients and compares favorably with exercise RNV.

Alteration of diastolic filling rate during exercise radionuclide angiography: a highly sensitive technique for detection of coronary artery disease.

Diastolic and systolic parameters of left ventricular performance were characterized from high-frequency time-activity curves obtained in 10 normal volunteers (mean age 29 +/- 4 yr), in 25 patients with normal coronary arteries, and in 50 patients with coronary artery disease (CAD) at rest and during three stages of exercise radionuclide angiography. In the normal volunteers ejection fraction was 65 +/- 5% (SD) at rest and 78 +/- 5% with exercise (p less than .001). In patients with normal coronary arteries ejection fraction was 64 +/- 5% at rest and 72 +/- 8% with exercise (p less than .0001). In patients with CAD resting ejection fraction was 60 +/- 10% and that during exercise was 61 +/- 13% (p = NS). Peak diastolic filling rate in the first half of diastole, peak systolic ejection rate, and times to peak rates and to end-systole were measured. In the normal subjects resting peak diastolic filling rate was 3.1 +/- 0.6 end-diastolic counts/sec and it increased in all subjects with exercise to 3.6 +/- 0.7 (p less than .05). In patients with normal arteries and those with CAD peak diastolic filling rate was 2.3 +/- 0.8 at rest and with exercise this parameter increased to 3.2 +/- 1.1 (p less than .001) in patients with normal arteries and fell to 1.7 +/- 0.6 in those with CAD (p less than .001). Peak systolic ejection rate decreased from 2.5 +/- 0.8 to 1.9 +/- 0.8 with exercise in patients with CAD (p less than .001).(ABSTRACT TRUNCATED AT 250 WORDS)

Cardioversion and "false positive" technetium-99m stannous pyrophosphate myocardial scintigrams.

The present studies performed in experimental animals demonstrate that electrical direct current cardioversion can produce skeletal muscle damage and increased technetium-99m stannous pyrophosphate (99mTc-PYP) uptake; in experimental animals the electrically damaged skeletal muscle shows necrosis with extensive calcium deposition. In addition, the frequent administration of high energy cardioversion produces myocardial necrosis with calcium deposition, increased 99mTc-PYP myocardial uptake and a positive 99mTc-PYP myocardial scintigram. The data indicate that, if diagnostic 99mTc-PYP myocardial scintigraphy is contemplated after cardioversion, paddle placement should be slightly removed from the anteroposterior projection of the heart on the external chest wall to avoid possible subsequent confusion between increased myocardial and skeletal muscle uptake of 99mTc-PYP. If multiple high energy cardioversion episodes are necessary, myocardial necrosis resulting from electrical injury may occur and be responisble for increased myocardial uptake of 99mTc-PYP with a resultant positive 99mTc-PYP myocardial scintigram.