Dynamic planar myocardial perfusion imaging in patients with one-vessel disease with intracoronary injection of technetium 99m teboroxime during papaverine-induced coronary hyperemia.

This study examined the imaging results and kinetics of technetium 99m teboroxime after its intracoronary injection during papaverine-induced coronary hyperemia in patients with one-vessel disease before and after coronary angioplasty. Thirteen patients with > or = 90% diameter stenosis of either the left anterior descending or the left circumflex coronary artery were included. Two patients were excluded because of ventricular tachycardia during papaverine injection in one patient and unsuccessful angioplasty in the second patient. One mCi of technetium 99m teboroxime was injected into the left main coronary artery during coronary hyperemia induced by intracoronary injection of papaverine. Dynamic acquisition in a frame mode (20 sec/frame) was performed for 5 minutes in the left anterior oblique projection with a multicrystal gamma camera before and after successful angioplasty. Ischemic:normal count ratio increased from 0.75 +/- 0.4 before to 1.00 +/- 0.50 after angioplasty (p < 0.1). The T 1/2 of teboroxime was 6.5 +/- 1.5 min in the normal zone and 7.2 +/- 1.9 min in the ischemic zone (p, NS). Perfusion defects were visible in the territory of the stenosed coronary artery in 9 of 11 patients before angioplasty and in 7 of 11 patients after angioplasty. The image quality was excellent in all studies. Thus this study shows that performing dynamic imaging with intracoronary injection of technetium 99m teboroxime is feasible. This technique may be useful to study the impact of angioplasty on coronary flow and tracer kinetics.

Detecting hibernated myocardium with SPECT and thallium-glucose-insulin infusion.

UNLABELLED: Because thallium kinetics, like potassium kinetics, may be affected by serum insulin levels, we performed two pilot studies to identify severely ischemic myocardium using different protocols based on the infusion of a thallium, insulin, potassium and glucose solution. Results were compared with those obtained with two currently used protocols based on rest injection or reinjection of 201Tl. METHODS: In the first study (Protocol 1) of 15 men with a previous large myocardial infarction, perfusion was evaluated by SPECT in 20 segments after a 30-min infusion of 201Tl (111 MBq), insulin (5 U) and potassium (10 mEq) in 10% glucose solution (250 ml). Imaging was repeated 30 min later and the results were compared with those obtained from stress and 3-hr reinjection images. In the second study (Protocol 2), 15 patients were evaluated randomly at rest and 3 hr later (rest-redistribution). On a separate day, the patients were then re-evaluated after infusion of 201Tl (111 MBq), potassium (10 mEq) and insulin (5 U) in 5% glucose (250 ml); images were obtained 90 and 180 min postinjection. RESULTS: In Protocol 1, radiotracer activity in segments with no uptake during stress was detected in 35% with the reinjection technique and 58% with the insulin solution protocol. In Protocol 2, 31% of segments revealed thallium activity after insulin infusion but not at rest or rest-redistribution. Serum measurements showed high insulin levels (444 +/- 138 in Protocol 1, 125 +/- 33 mU/ml in Protocol 2), although glucose levels were not significantly altered (149 +/- 32 versus 71 +/- 20 mg/dl, respectively). Potassemia was not affected and the patients tolerated the tests satisfactorily. CONCLUSION: These results confirm that continuous infusion of 201Tl with a low dose of insulin in a glucose/potassium chloride solution is safe and may enhance cellular uptake of the radiotracer in severe ischemic regions, thereby improving viable myocardium detection.

[Multiple spontaneous coronary dissection. Case report and review of the literature]. / Dissezione coronarica spontanea multipla. Descrizione di un caso e revisione della letteratura.

We refer a case of a 57-year-old woman with an acute myocardial infarction of the anterior wall, treated with rt-PA, aspirin and heparin. In the following days, in spite of the therapy, occurred a second acute myocardial infarction of the inferior wall complicated with ventricular fibrillation. Coronary angiography showed multiple coronary dissection involving the left anterior descending and the circumflex coronary arteries. The characteristic feature of this case consists of the multiple coronary dissection responsible for myocardial infarctions, an event seldom reported in the literature.

[Identification of viable myocardium by 201Tl scintigraphy: a comparison of methods]. / Identifizierung des vitalen Myokards mit der 201Tl-Szintigraphie: Ein Vergleich der Methoden.

The present study was undertaken to compare four different imaging approaches to evaluate uptake defect reversibility. 24 infarcted patients underwent standard stress/redistribution 201Tl imaging (R1). Then, after reinjection of 37 MBq of 201Tl, patients were re-imaged either after 15 min (R2) 24 h later (R3). A separate rest study (R4) following a new tracer injection was done within 2-3 days. Planar images were obtained in the standard three views and subdivided into 216 segments for qualitative analysis based on a visual score. A semiquantitative analysis based upon circumferential profiles was also applied. A stress defect was found in 127 segments (58.7%). By visual inspection reperfusion was considered to occur in 32.3%, 41.7%, 33.0% and 49.6% of the cases with R1, R2, R3, and R4, respectively. The semiquantitative method showed a high reperfusion only with R1 (62%), while the other procedures proved less effective. No improvement was found with R4. Six patients (25%) showed myocardial viability that was not detected with the early reinjection technique.

A comparison of rest sestamibi and rest-redistribution thallium single photon emission tomography: possible implications for myocardial viability detection in infarcted patients.

Thirty patients (26 men, 4 women, mean age 61 +/- 8 years) who had suffered myocardial infarction 15 +/- 6 months previously, were submitted to (1) standard stress-redistribution thallium-201 single photon emission tomography (SPET), (2) rest-redistribution 201T1 SPET and (3) stress-rest technetium-99m sestamibi SPET. Uptake modifications in relation to exercise-induced defects were evaluated in a total of 390 myocardial segments. Tracer uptake was scored as normal (=0), mildly reduced (=1), apparently reduced (=2), severely reduced (=3) or absent (=4). Comparison of stress studies failed to show any statistical difference (58% segmental abnormalities with sestamibi vs 61% with thallium). Uptake abnormalities (score 1-4) were detected in 55% of the segments with sestamibi, 55% with standard thallium redistribution, 55% with early imaging after thallium injection at rest and 54% with 3-h delayed rest imaging (P = NS). Absence of tracer uptake (score = 4) under resting conditions was recorded in 75 (19%) segments with standard 201T1 redistribution, 75 (19%) with rest sestamibi, 70 (18%) with rest 201T1 imaging and 62 (16%) with rst-redistribuion 201T1 (P < 0.05 vs other imaging modalities). Thus, 3-h delayed rest thallium imaging detected reversibility of uptake defects in a significantly higher number of myocardial segments. This finding might have important implications for both tracer and technique selection when myocardial viability is the main clinical issue.

Effects of nisoldipine in coronary artery disease: a radioisotopic approach.

The clinical, electrocardiographic, and scintigraphic effects of oral administration of nisoldipine were investigated using two separate study protocols. In the first, the acute effects of nisoldipine were evaluated by means of nuclear ventricolography and demonstrated no deleterious effects on global contractility and an amelioration of several hypokinetic segments. In the second protocol, myocardial perfusion effects were evaluated by means of tomoscintigraphy. An improvement of segmental uptake of thallium was caused by nisoldipine. The addition of atenolol markedly reduced the rate-pressure product and further improved myocardial perfusion.

Clinical evaluation of four study protocols with 99mTc-methoxyisobutylisonitrile and SPECT for detecting diseased coronary vessels.

Different techniques have been suggested for coronary artery disease (CAD) detection with single-photon emission computed tomography (SPECT) and 99mTc-methoxyisobutylisonitrile (99mTc-MIBI). We evaluated four protocols employing myocardial SPECT with 99mTc-MIBI in separate groups of patients. The first involved stress and rest studies performed on separate days, whereas the other three involved "same day" studies. Group 1 (n = 23) was examined in separate sessions, after ergometric exercise and at rest. Group 2 (n = 24) was first injected after dipyridamole infusion, then injected again at rest after completion of the stress study. Group 3 (n = 24) was first injected at rest and imaged one hour later. Afterwards an ergometric stress was performed, with injection at peak exercise. The inverse sequence was adopted for group 4 (n = 24). All patients underwent coronary angiography. For all groups and vessels, the sensitivity and specificity for diseased coronary artery identification were not statistically different. Studies using the new myocardial perfusion tracer 99mTc-MIBI may therefore be completed on the same day or on separate days according to laboratory and patient needs. Dipyridamole iv infusion proved to be as effective as ergometric exercise for diseased coronary artery identification.

Dipyridamole technetium-99m-2-methoxy isobutyl isonitrile tomoscintigraphic imaging for identifying diseased coronary vessels: comparison with thallium-201 stress-rest study.

A same-day double injection protocol employing 99mTc-methoxyisobutyl isonitrile (MIBI) and myocardial single-photon emission computed tomography (SPECT) for detecting coronary artery disease (CAD) was assessed in 30 patients. SPECT was performed 1 hr after a first injection (250 MBq) of 99mTc-MIBI, given after 0.56 mg/kg dipyridamole (DPD) infusion. Patients were then reinjected at rest (750 MBq) and were reimaged 1 hr later. Within 1 wk, all patients underwent a complete stress-rest SPECT thallium study. Of the 330 myocardial segments evaluated, 25 were judged ischemic by both techniques, while persistent defects were demonstrated in 50 and in 47 with 99mTc-MIBI and 201TI, respectively. Six regions were considered for diseased vessels identification. Sensitivity and specificity for CAD were 100% and 75%, respectively, for both 201TI and 99mTc-MIBI. Sensitivity for identification of diseased vessels by 201TI was 68% for LAD, 89% for RCA, and 80% for LCX as opposed to 75%, 89% and 80%, respectively, by 99mTc-MIBI. Specificity was 93% in both cases for LAD, 73% and 63% for RCA, and 53% and 46% for LCX.

Myocardial metabolic and hemodynamic effects of a sustained intravenous infusion of nifedipine with and without metoprolol in patients with unstable angina.

We tested the usefulness of a sustained intravenous infusion of nifedipine and a combination of nifedipine and metoprolol in the early management of 14 patients with unstable angina pectoris. After a 24-hour run-in period, nifedipine was titrated in a stepwise fashion (mean dose 27 +/- 7 micrograms/min). After nifedipine treatment coronary blood flow increased from 150 +/- 66 to 183 +/- 74 ml/min (p less than 0.05), whereas double product, myocardial oxygen consumption, and both arterial and coronary sinus (nor)epinephrine levels were unchanged. Myocardial lactate uptake increased from 3.4 +/- 26.1 to 31.3 +/- 26.6 mumol/min (p less than 0.005) and free fatty acid uptake from 7.2 +/- 22.1 to 34.5 +/- 33.7 mumol/min (p less than 0.05). A small nonsignificant improvement in amino acid metabolism was observed. Metoprolol was added in seven patients and led to a decrease in double product (-2.2 +/- 1.6 x 10(3); p less than 0.01) and myocardial oxygen consumption (-3.2 +/- 3.8 ml/min; p less than 0.05). The lactate uptake/oxygen uptake ratio increased by 18% after metoprolol (p = NS). The number of episodes of chest pain decreased from 2.4 +/- 1.1/24 hours to 0.1 +/- 0.2 in the nifedipine group and from 2.9 +/- 1.1/24 hours to 0.3 +/- 0.5 in the nifedipine plus metoprolol group (both p less than 0.01). We conclude that in the acute phase of unstable angina, intravenous nifedipine can be carefully titrated to improve coronary blood flow and oxidative metabolism. The addition of metoprolol is also associated with a reduction in myocardial oxygen demand. This treatment results in significant hemodynamic stability.

[Double injection of Tc99m-methoxy isobutyl isonitrile in the same session: diagnostic accuracy in tomography compared with that of thallium-201 chloride]. / Doppia iniezione di tecnezio 99m metossi isobutil isonitrile nella stessa seduta: accuratezza diagnostica dell'indagine tomografica rispetto a quella con tallio-201 cloruro.

Radionuclide imaging with thallium-201 is widely accepted for identifying the presence and the severity of coronary artery disease, but this radiotracer is hampered by some limitations (low-energy photons and long physical half-life) and by delivering difficulties. Therefore, various technetium 99m-labelled compounds have been proposed as myocardial perfusion agents. In particular, technetium 99m methoxy isobutyl isonitrile (Tc99m-MIBI) showed the most favourable characteristics for clinical applications. Recently a study protocol involving a split dose of the radiocompound injected in the same day has been proposed. The aim of this work has been to evaluate the diagnostic accuracy of this procedure coupled with tomographic study (SPECT-MIBI) in a group of patients with documented coronary artery disease and to compare the results with those obtained by means of Tl-201 tomographic studies (SPECT-Tl) in the same patient group. Twenty-four patients, 21 males and 3 females, entered the study: the mean age was 57 +/- 6 years (44-71). For the rest study the patients were given 250 MBq of Tc99m-MIBI. Then, after 2-3 hours, they were reinjected with a second dose of 750 MBq when exercise endpoints were reached. The studies with Tl-201 were carried out the week before or subsequent the Tc99m-MIBI studies. Sensitivity was 88% with SPECT-Tl and 78% with SPECT-MIBI for the anterior descending artery (LAD), 86% and 64% respectively for right coronary artery disease (RCA) and 69% with both procedures for the left circumflex artery (LCX). Specificity was 88% with SPECT-Tl and 78% with SPECT-MIBI LAD, 60% with both procedures for RCA and 55% and 81% respectively for LCX. Coronary artery disease, involving 2 or more vessels, was correctly identified in 93% of patients by Tl-201 studies and only in 60% of patients by Tc99m-MIBI. In several cases the high count rate obtained by Tc99m-MIBI did not allow the identification of hypoperfused segments. In conclusion, a rest-stress double injection of Tc99m-MIBI in a same-day protocol has shown a lower sensitivity for detecting coronary lesions than Tl-201. Moreover, radiation exposure for medical and technical staff is greater with Tc99m-MIBI than with Tl-201.

Regional left ventricular ejection fraction with single crystal gammacamera and gated equilibrium technique: repeatability and inter-observer variability.

Regional left ventricular ejection fraction calculated by means of gated blood pool scintigraphy was compared with that obtained from contrast ventriculography in a group of 20 patients, submitted to both procedures within a month. To evaluate repeatability both at rest and during stress, a second scintigraphic study was carried out after three weeks, with no change in drug regimen. Inter-observer variability was assessed in a randomly selected subgroup of 16 patients, in whom a computation was repeated by a second operator. Comparison of scintigraphic results showed a satisfactory agreement, and measurement agreement for global left ventricular ejection fraction was very good. As regards interobserver variability, each of the three myocardial segments examined (septal, lateral and infero-apical) showed good agreement. As regards repeatability, global left ventricular ejection fraction, proved readily reproducible both for rest and stress studies, with relatively small differences in observed values. Regional ejection fraction, on the other hand, had a high variability, especially during stress. It is suggested that for regional ejection fraction evaluation, reproducibility studies should be performed in order to better correlate result changes to clinical outcome after medical or surgical therapy.

Diagnostic accuracy of single photon emission computed tomography with thallium-201 for the identification of diseased coronary arteries. Comparison between dipyridamole infusion and exercise stress test.

Myocardial perfusion imaging with 201Tl and single-photon emission computed tomography (SPECT) was carried out in two groups of patients, subsequently submitted to diagnostic coronary angiography. SPECT was performed in group 1 (41 patients) after slow i.v. infusion of dipyridamole and in group 2 (162 patients) after tracer injection at maximal ergometric exercise. To evaluate the diagnostic capability of SPECT in the detection of diseased coronary vessels, the left ventricular myocardium was subdivided into 6 segments related to the three major coronary arteries. Sensitivity for the left anterior descending artery was 77% in group 1 and 79% in group 2; specificity was 80% and 96%, respectively. Sensitivity for the right coronary artery was 91% in group 1 and 85% in group 2; specificity was 81% and 73%. For the left circumflex artery sensitivity was 65% for group 1 and 67% for group 2, while specificity was 89% and 88%, respectively. Myocardial SPECT results after ergometric exercise and dipyridamole infusion turned out to be almost superimposable. Dipyridamole stress might be considered appropriate as a provocative test when physical exercise cannot be carried out.

[Analysis of the diastolic function of the left ventricle by Doppler echocardiography in athletes engaged in competitive sports activities]. / Analisi della funzione diastolica del ventricolo sinistro mediante eco-Doppler nell'atleta praticante attività sportiva agonistica.

In order to assess left ventricular diastolic function in elite athletes we studied 24 athletes (mean age 21 +/- 5 years) with the echo-Doppler technique. The control group consisted of 14 healthy males (mean age 24 +/- 6 years) and 99 patients (mean age 50 +/- 14 years) with primary or secondary left ventricular hypertrophy. The following variables were calculated: age, systolic and diastolic blood pressure, septal and posterior wall thickness, left ventricular volume and dimensions, myocardial mass index and mass/volume ratio, left ventricular end-systolic and peak systolic stress, RR interval, isovolumic relaxation time (IVRT), early (E) and late (A) peak flow velocity, E/A ratio, time and rate of deceleration of early diastolic flow. Compared with the normal subjects significant differences were observed with regard to systolic blood pressure, left ventricular wall thickness, myocardial mass, mass/volume ratio and peak systolic stress in the athlete group. In spite of a noticeable increase in myocardial mass indexes, all the diastolic function parameters were normal in the athletes. In this group a linear positive correlation between rapid filling indexes, ventricular mass and mass/volume ratio exists. These correlations are not present in the patients group. Moreover a linear negative correlation between RR interval and late diastolic flow velocity was found. In conclusion, the global diastolic ventricular function, evaluated with the echo-Doppler technique, is normal in athletes in spite of an increase in ventricular mass. Th early diastolic flow velocity is in direct proportion with mass increase and may represent one of the physiological mechanisms of the athlete heart adaptations.

Radionuclide evaluation of ventricular function at rest and during exercise in double inlet ventricle.

We studied ventricular volumes and ejection fraction by radionuclide angiography (equilibrium technique) in 15 patients (aged 3-48 years) with double inlet ventricle not yet submitted to corrective surgery. The end-diastolic volume (measured in nine cases) ranged from 108 to 219 ml/m2 (156 +/- 32), being lower than the normal theoretical value (right plus left ventricle) in six cases. Ejection fraction ranged from 30 to 77% (56.4 +/- 13). The value was significantly higher in the subgroup of 10 patients with a dominant left ventricle as compared to the five cases with dominant right or indeterminate ventricular morphology (63.2 +/- 8.3 versus 42.8 +/- 9, P less than 0.01). In seven of the 15 patients, measurements were obtained both at rest and during dynamic exercise in the semi-upright position. The end-diastolic and end-systolic volumes, stroke volume, ejection fraction underwent a slight non-significant reduction (from 158 +/- 29 to 147 +/- 24 ml/m2, from 58 +/- 16 to 56 +/- 24 ml/m2, from 100 +/- 27 to 90 +/- 24 ml/m2, from 64% +/- 9 to 61% +/- 13). During exercise, ventricular volumes mostly behaved as follows: slight reduction of end-systolic volume, decrease of end-diastolic volume, no increase (no change or decrease) of ejection fraction.(ABSTRACT TRUNCATED AT 250 WORDS)

Clinical and hemodynamic effects of long-term administration of gallopamil in patients with coronary artery disease and normal or impaired left ventricular function.

The hemodynamic and clinical profiles of gallopamil, a new calcium antagonist, were evaluated in 20 patients with severe coronary artery disease in a placebo-controlled, single-blind study. The patients were divided into 2 groups depending on baseline ejection fraction (greater than 45 or less than or equal to 45%) and underwent nuclear ventriculography, both at rest and during bicycle exercise under electrocardiographic monitoring, after 3 weeks of therapy (50 mg 3 times daily) and the 1-week run in and washout placebo periods. The mean anginal weekly frequency per patient was significantly reduced, from 3.4 to 0.5 (p less than 0.001). The left ventricular ejection fraction, cardiac volumes, ejection and filling indexes at rest and for the same workload were not altered in the population as a whole or in each of the 2 groups. The rate pressure product during exercise was reduced for the same workload from 18.0 +/- 5.0 X 10(3) to 16.8 +/- 4.7 X 10(3), while the regional ejection fraction in ischemic regions was not significantly changed. Individual variations of ventriculographic parameters in both groups were not related to basal values. Gallopamil increased the total duration of exercise from 432 +/- 201 to 537 +/- 188 s (p less than 0.001). Six patients did not complain of angina and their exercise was interrupted because of muscular weakness. The hemodynamic and clinical responses did not differ when the results in the population as a whole and in each of the 2 groups were compared. Gallopamil was effective and well tolerated, even in patients with very depressed cardiac function.

Interaction study of fenoldopam--digoxin in congestive heart failure.

The potential interaction between fenoldopam, a DA1 selective agonist, and digoxin has been studied in 10 patients with heart failure (NYHA Class II or III) on chronic digoxin treatment. Plasma levels and urinary recovery of the glycoside were monitored for 24 h before and after 9 days of treatment with fenoldopam 100 mg tid. Fenoldopam caused a small, non-significant decrease in the mean steady state plasma concentration and area under the plasma concentration curve of digoxin. As the clearance of digoxin was unchanged there does not appear to be an interaction between fenoldopam and digoxin at the level of the renal tubule.