Myocardial scintigraphy with 99mtechnetium stannous pyrophosphate in patients with possible acute myocardial infarction

Fifty-six patients with a preliminary diagnosis of possible acute myocardial infarction (AMI) were studied on the second or third day after onset of symptoms by 99mtechnetium stannous pyrophosphate myocardial imaging. The scintigraphy was positive in 25 (44.6%). The final clinical diagnoses upon discharge were: definite AMI in 11 with positive scintigraphy in 9 (82%), intermediate coronary syndrome (ICS) in 37 with positive scintigraphy in 15 (40.5%), postinfarction failure in 4 with positive scintigraphy in 1, no diagnosis of coronary heart disease in 4 patients with negative scintigraphy in all. Of the 37 patients with a final diagnosis of ICS, 25 were admitted to the Coronary Care Unit with chest pain as the only symptom. In this group the mean percentage increase in ASAT was significantly higher in 9 patients with positive scintigrams than in 16 with negative. It is therefore assumed that among patients with ICS, a positive scintigraphy may reflect a more serious myocardial injury than a negative scintigram. Of six patients with an acute tachyarrhythmia and ICS, scintigraphy was positive in the three with the most long-lasting or severe arrhythmmias. False negative scintigrams may be seen in some patients with definite AMI.

Poor Labeling of Tc-99m Red Blood Cells In Vivo in a Radionuclide Intestinal Bleeding Study of a Patient Who Had Recently Undergone Frequent Blood Transfusions

The authors report poor labeling of Tc-99m red blood cells (RBCs) in vivo in a radionuclide intestinal bleeding study of a patient who had recently undergone frequent blood transfusions. The existence of RBC antibodies, as a result of the recent blood transfusions in this patient, was one of the causes of the poor labeling. In radionuclide bleeding studies with patients with recent blood transfusion, Tc-99m HSA-D must be chosen instead of Tc-99m RBCs in vivo.

Technetium-labelled red blood cell scintigraphy: is it useful in acute lower gastrointestinal bleeding?

Radionuclide scintigraphy is commonly utilized as a screening examination before performing more invasive procedures in the work-up of patients with lower gastrointestinal (GI) bleeding. We reviewed our institutional experience with technetium-labelled red blood cell scintigraphy (TRCS) in detecting and localising acute lower GI bleeding. The study group included 72 patients who had 80 red cells scans over a five year period. Thirty-eight scans were positive (47.5%), and 42 were negative (52.5%). Sites of lower GI bleeding were confirmed by endoscopy, arteriography, surgery and/or pathology in 22 of the 38 positive scans. There were four false-negative scans (9.5%). The overall sensitivity and specificity of TRCS in detecting lower GI bleeding was 84.6% (22/26) and 70.4% (38/54), respectively. The accuracy of localization of bleeding sites in the patients with confirmed positive scans was 72.7% (16/22). Thirty mesenteric arteriograms were performed on patients in this series. Eleven arteriograms were performed after negative TRCS; one was positive. Technetium-labelled red blood cell scintigraphy appears to be a useful screening examination for patients with lower GI bleeding who are hemodynamically stable. This may avoid the potential morbidity of arteriography in patients who are not actively bleeding.

Does impedance cardiography reliably estimate left ventricular ejection fraction?

OBJECTIVE

The objective of our study was to evaluate impedance cardiography (IMP) as a noninvasive method to determine the left ventricular ejection fraction (LVEF). METHODS. A total of 24 patients, 8 men and 16 women, aged 45.0 +/- 12.9 years, participated in the study. They used cardiotoxic chemotherapeutic drugs or suffered from cardiac failure. LVEF was measured by means of IMP (LVEFimp) and radionuclide ventriculography (LVEFnuc). LVEFimp was calculated in three ways. Capan and colleagues [13] proposed a formula in which LVEF (LVEFCap) can be calculated from the systolic time intervals, namely, left ventricular ejection time and preejection time. Judy and colleagues [14] described a systolic (S) and a diastolic (D) part in the first derivative curve of the impedance signal. The ratio S/D might equal the LVEF (LVEFJud). A new LVEF calculation was introduced (LVEFimp) in this study based on the first derivative of the impedance signal, the thoracic impedance, and heart rate.

RESULTS

Mean LVEFCap was 59.9 +/- 8.4%, which did not differ from LVEFnuc (59.9 +/- 7.1%). However the correlation between both methods was not significant (r = 0.29). Mean LVEFJud was 63.9 +/- 17.4%, which was not significantly different from LVEFnuc, with a fair correlation (r = 0.55). Mean LVEFimp was 59.2 +/- 9.4%, with a better correlation with radionuclide ventriculography (r = 0.75).

CONCLUSIONS

The results of this study indicate that the equations that have been used until now can be improved. The new equation provides reliable LVEF values in this group of patients.

Effect of stannous pyrophosphate red blood cell gastrointestinal bleeding scan on subsequent Meckel's scan

Both labeled RBC and Meckel's scans have been used to evaluate pediatric patients with gastrointestinal bleeding, sometimes sequentially in the same patient. Particularly in infants, from whom withdrawal of sufficient blood for in vitro RBC labeling is often not possible, in vivo labeling with stannous pyrophosphate is used. However, prior administration of stannous-containing agents is known to alter the in vivo distribution of Tc-99m pertechnetate and to interfere with the subsequent Meckel's scan. The authors report on a Meckel's scan performed on an infant 1 week after a GI bleeding study with Tc-99m and stannous pyrophosphate. The Meckel's scan shows abnormal tracer distribution with absent gastric uptake, rendering the scan uninterpretable. In pediatric patients with gastrointestinal bleeding, a Meckel's scan should be done before labeled RBC imaging.

Elution characteristics of 99Tcm-labelled erythrocytes in relation to scintigraphic detection of gastrointestinal bleeding

Radionuclide imaging for the detection and localization of gastrointestinal bleeding is a highly sensitive and well-established clinical tool. 99Tcm-labelled erythrocytes have permitted the recognition of intermittent bleeding up to 24 h following injection. However, free pertechnetate is actively secreted by gastric mucosa and can result in confounding gut activity. The possibility that pertechnetate may elute from the radiolabelled erythrocytes was investigated in an in vitro model. Blood samples from five subjects undergoing gated cardiac studies were labelled by modified in vivo, modified in vitro and pure in vitro methods and then incubated in serum for 24 h. Automated cell counts and instant thin layer chromatography were used to measure the physical and radiochemical stability of the labelled erythrocytes. No detectable haemolysis occurred and no free pertechnetate was released from the cells. However, an unexpected hydrophilic 99Tcm species became detectable in the supernatant with a quantitative index which increased from an initial value of 0.016 +/- 0.004 to 0.079 +/- 0.012 at 24 h (P less than 0.00001). This index did not differ among the three labelling methods. A chromatographically similar material was identified in the urine of a patient undergoing a gastrointestinal bleed study. The possibility of gut and/or hepatobiliary secretion of this material needs further clarification before delayed positive studies can be relied upon to indicate gastrointestinal bleeding.

[Competitive sports activity in subjects undergoing the surgical correction of an ostium-secundum type of interatrial defect: the experience of 9 cases]

Patients who have undergone surgical repair of congenital heart diseases are usually not allowed to participate in competitive sports. In the present study we report our long-term experience with 9 male athletes aged 17 to 23 years who participate in competitive sports after undergoing surgical repair of ostium secundum atrial septal defect at a median age of 9 years; six of them play football and three of them volleyball. Competitive sport activities began 1 to 5 years after surgical repair. The mean duration of follow-up is 88 +/- 26 months. Sport fitness was granted on the basis of the following criteria: 1) a normal physical examination; 2) a normal working capacity on exercise test; 3) no arrhythmias on exercise test and Holter monitoring, recorded also during sport activities; 4) a normal M-mode and two-dimensional echocardiography, including the normalization of right ventricular size; the persistence of an abnormal ventricular septal motion did not exclude sport fitness. Recently we also performed Doppler and color Doppler echocardiography and gated equilibrium radionuclide angiography at rest and during exercise. We studied left ventricular diastolic filling through the pulsed wave Doppler evaluation of transmitral flow and measured cardiac output by continuous wave Doppler echocardiography during exercise test in the supine position. We also performed exercise test and M-mode, two-dimensional, Doppler and color Doppler echocardiography in a control group made up of 15 athletes (10 football players and 5 volleyball players). The exercise duration at graded treadmill exercise test (according to the Carù protocol), the maximal heart rate and the maximal systolic blood pressure were, respectively, 12.9 +/- 0.8 min, 192 +/- 10 beats/min and 198 +/- 12 mmHg. Left ventricular end-diastolic dimension, mass and ejection fraction (single-plane area-length method) were 50.3 +/- 2.8 mm, 210 +/- 38 g and 65 +/- 6%. M-mode right ventricular diastolic dimension was 23.4 +/- 1.6 mm; the right ventricular maximal diastolic diameter and area obtained on two-dimensional echocardiography from the apical four chamber view were 44.1 +/- 3.6 mm and 25 +/- 3.8 cm2 respectively. The evaluation of transmitral flow showed the following data: E velocity 77 +/- 12 cm/sec, A velocity 45 +/- 6 cm/sec, E/A ratio 1.7 +/- 0.3, the isovolumic-relaxation period 72 +/- 8 m/sec and the deceleration half-time of the early rapid filling 71 +/- 10 m/sec. A trivial tricuspid regurgitation was detected in 6 subjects; the peak velocity of the regurgitant jet was less than 2.1 m/sec.(ABSTRACT TRUNCATED AT 400 WORDS)

Gated cardiac blood pool studies in atrial fibrillation: role of cycle length windowing

Cycle length windowing is gaining increasing acceptance in gated blood pool imaging of patients with atrial fibrillation (AF). The goals of this study were: to assess differences of ejection fraction (EF) in AF with and without windowing and to determine how EF varied with cycle length in patients with AF. Twenty patients with AF were prospectively studied by gated blood pool imaging, with simultaneous collection in each patient of 5-7 studies with cycle length windows spanning the cycle length histogram. Each window accepted beats of only a narrow range of cycle lengths. EF was determined for each of the narrow cycle length windows as well as for the entire gated blood pool study without cycle length windowing. For every patient an average of the windowed EFs was compared with the non-windowed EF. EF values were similar (mean windowed: 46.6; non-windowed: 45.5; P = 0.16), and there was a good correlation between the two techniques (r = 0.97). The data were then examined for a relationship of EF with cycle length. The difference from average windowed EF (delta EF) was calculated for each window and plotted vs. the cycle length of the center of each window. No predictable linear or nonlinear relationship of delta EF with window position was observed. Lack of predictable variation of EF with cycle length is likely due to lack of a predictable amount of ventricular filling for a given cycle length, as the amount of diastolic filling in AF depends on the random cycle length of the preceding beat.(ABSTRACT TRUNCATED AT 250 WORDS)

[Myocardial 99mTc-pyrophosphate scintigraphy in acute heart infarct]

50 consecutive patients hospitalized because of suspected myocardial infarction were examined by 99mTc-pyrophosphate scintigraphy. The scans were interpreted blind by one of the authors. There were positive results in 17 of 21 patients with myocardial infarction (sensitivity 0.81). However, scintigraphy was also positive in 13 patients with no evidence of myocardial infarction as assessed by ECG and enzyme criteria (specificity 0.55). We conclude that, in our hospital, 99mTc-pyrophosphate myocardial scintigraphy did not contribute valuable information to the routine diagnosis of myocardial infarction.

Ventricular systolic and diastolic rate indices in patients with either normal or low resting left ventricular ejection fraction

To investigate the potential uses of right and left ventricular systolic and diastolic rate indices in identifying patients with ischaemic heart disease (IHD), gated blood-pool imaging was performed for 19 normal subjects (group 1) and 56 patients, of whom 31 had resting LVEF greater than or equal to 50% (group 2) and 25 had resting LVEF less than or equal to 50 (group 3). The peak ejection rate (PER) and peak filling rate (PFR), their timing and the mean filling rate (MFR) were derived from the time-activity curves analysis. Group 2 patients had significantly reduced LV PER and PFR (3.00 +/- 0.58 EDV/s, p less than 0.005, 2.29 +/- 0.54 EDV/s, p less than 0.0009) as compared to normal (3.90 +/- 0.70 EDV/s and 3.35 +/- 0.80 EDV/s respectively). Patients with profoundly depressed LVEF had significantly low PER and PFR (1.96 +/- 0.50 EDV/s, 1.46 +/- 0.27 EDV/s respectively). However, there was considerable overlap in values between groups. Therefore, we conclude that there is no single parameter more sensitive than LVEF in identifying IHD patients with normal LVEF at rest.

99mTc-SN-pyrophosphate scintigraphy following traumatic posterior dislocation of the hip

Avascular necrosis of the head of the femur is a serious complication of traumatic dislocation of the hip joint; therefore 99mTc-SN-pyrophosphate scintigraphy was carried out 10 to 14 weeks (average 12 weeks) after the injury on 12 patients to determine whether it was possible to demonstrate reduced or no activity of the head of the femur before development of radiological avascular necrosis of the head of the femur. Increased activity was observed in 9 of 11 hips with fracture-dislocation of the head of the femur, acetabulum or both, and normal activity was demonstrated in the contralateral hip of all patients. During the follow-up period avascular necrosis of the head of the femur developed in four hips from 6 to 20 months after the accident. It is concluded that 99mTc-SN-pyrophosphate scintigraphy 12 weeks after traumatic dislocation of the hip was unable to identify hips at risk of later development of avascular necrosis of the head of the femur.

Vectorcardiographic criteria for acute right ventricular infarction

Based on serial vectorcardiographic and cardiac scintigraphic studies of 62 patients with acute myocardial infarction, we propose vectorcardiographic criteria for the diagnosis of acute right ventricular infarction. These criteria are: (1) the direction of the maximal spatial ST vector points either to the right-anterior-inferior or to the right-posterior-inferior octant, and (2) the magnitude of the projection of the maximal spatial ST vector is greater than or equal to 0.15 mV in the horizontal plane. By using these criteria correlated with scintigraphic results, 92% sensitivity was achieved together with 98% specificity; the Kappa statistic was 0.90. In patients with acute inferior and right ventricular infarction, the serial maximal spatial ST vector swung to-and-fro like a 'tug of war' between right-anterior-inferior and right-posterior-inferior octants during the acute stage. In patients with acute inferior-posterior and right ventricular infarction, the serial maximal spatial ST vector pointed to the right-posterior-inferior octant during the whole course of the acute stage. Failure to recognize this electrical phenomenon may make the clinician inaccurate when judging the clinical course of acute right ventricular infarction or over-estimate the result of therapeutic intervention.

Postural exercise abnormalities in symptomatic patients with mitral valve prolapse

The hemodynamics of the supine and upright exercise response in 16 symptomatic women with mitral valve prolapse (Group I) was compared with that in 8 asymptomatic normal control women (Group II). All subjects had supine and upright echocardiography and phonocardiography at rest and none demonstrated mitral regurgitation. All participants then underwent same day graded bicycle exercise, with simultaneous radionuclide angiography in both the upright and the supine posture. Catecholamines were measured, and a variety of volumetric and hemodynamic data were obtained. Group I (patients with mitral valve prolapse) demonstrated a reduced exercise tolerance, especially during upright exercise, as measured by both total exercise duration and maximal work load achieved. Mean total catecholamine measurements were similar between the two study groups at comparable mean heart rate, mean blood pressure and mean rate-pressure (double) product. No difference was observed in the ratio of right to left ventricular stroke counts at rest or during exercise regardless of posture, suggesting that exercise-induced mitral regurgitation did not occur. A difference was noted, however, in left ventricular end-diastolic volume index. At rest, Group I patients exhibited a 42% decrease in this index when sitting upright, and this difference from supine values persisted at submaximal (300 kpm/min) and peak work loads (34 and 29% difference, respectively). This contrasted with the control subjects whose upright end-diastolic volumes at rest, at 300 kpm/min and at peak exercise were reduced 21, 10 and 3%, respectively, compared with supine values. Cardiac index measurements reflected the reduced left ventricular end-diastolic volume observed.(ABSTRACT TRUNCATED AT 250 WORDS)

Stabilization of stannous pyrophosphate kits with gentisic acid

We evaluated the ability of gentisic acid, an antioxidant, to stabilize stannous pyrophosphate (Sn:PPi) kits and extend the shelf-life of the kit after reconstitution. In vitro studies showed that gentisic acid (0.5 mg/mL) stabilized the stannous ion against oxidation by various levels of exogenous hydrogen peroxide. In patients who received stabilized Sn:PPi for in vivo red blood cell labelling, the left ventricle-to-background activity ratio was significantly higher than that in patients who received a standard formation of Sn:PPi. Gentisic acid is now used routinely in the Sn:PPi kit formulation in this institution.

Usefulness of early positive technetium-99m stannous pyrophosphate scan in predicting reperfusion after thrombolytic therapy for acute myocardial infarction

To test the hypothesis that scans with technetium-99m pyrophosphate (Tc-99m-PPi) are positive when performed early after successful thrombolytic therapy for acute myocardial infarction (AMI), 16 consecutive patients with AMI who received thrombolytic therapy within 5 hours after the onset of chest pain were studied. Patients were included if chest pain lasted for greater than 30 minutes, was unresponsive to sublingual nitroglycerin and was associated with at least 0.2 mV ST-segment elevation in at least 2 contiguous electrocardiographic leads. All patients received 1.5 million IU of streptokinase intravenously, a mean of 195 +/- 99 minutes after onset of chest pain. Tc-99m-PPi scans and coronary cineangiograms were recorded 491 +/- 156 minutes and 518 +/- 202 minutes, respectively, after the onset of symptoms. Effective reperfusion was present in 10 patients, 6 of whom had positive Tc-99m-PPi scans (sensitivity of 60% to detect reperfusion). Of the 6 patients without effective reperfusion, 3 had positive Tc-99m-PPi scans (specificity of 50%, p greater than 0.05). Analysis of the data using various definitions of effective reperfusion or artery patency yielded similar results. Thus, our findings indicate that early AMI scanning with Tc-99m-PPi does not accurately detect the presence or absence of reperfusion in patients with AMI after treatment with intravenous streptokinase. At this time, coronary cineangiography is the only reliable method to detect reperfusion promptly after thrombolytic therapy.

99mTc bone scanning agents--IV. Chemical characterization of 99mTc(Sn)-pyrophosphate complexes

Various reaction mixtures for the preparation of 99Tc(Sn)-pyrophosphate were investigated by means of gel chromatography. All components were radioactively labeled. The most likely composition of the complexes, which also appear in "no carrier added" preparations, was determined. At pH 7 one complex is found with the composition TcPyp2. Two complexes are found at pH 4: TcPyp and TcPyp2. Further, at pH 7 a polymeric technetium compound is found not containing tin or pyrophosphate.

Early imaging of the infarct

Radionuclide techniques for the detection of acutely infarcted myocardium have been available for several years, but they are rarely used. Recent advances, such as the introduction of single-photon emission computed tomography and the introduction of novel radiopharmaceuticals, have suggested new clinical and research applications for them.

Mechanisms of changes in nitrogen washout and lung volumes after saline infusion in humans

This study was performed to determine the roles of increased intrathoracic blood volume and increased vagal tone in the changes in lung volume and nitrogen washout produced by saline infusion. In the first study, measurements of TLC, VC, FRC, ERV, and slope of phase III nitrogen washout (delta N2) were made on 8 subjects before, during, and after inflation of the leg compartments of medical anti-shock trousers (MAST). In the second study, 13 volunteers were infused intravenously with warm saline (30 ml/kg) for 30 min. Repeat measurements were made approximately 20 and 40 min after infusion. Each subject then received intravenously 0.03 mg/kg atropine, and measurements were repeated. In 7 of these subjects, a third study was performed in which the atropine was injected before saline infusion. Inflation of the MAST (see figures 5 and 6) caused a 1.9% decrease in VC, 5.3% decrease in FRC, and no change in delta N2. Saline infusion caused decreases in TLC, VC, and FRC (4.0, 3.1, and 10.1%, respectively) and a 15.0% increase in delta N2. Atropine reversed the change in delta N2 after saline infusion and prevented these changes when given prior to saline. Atropine had no effect on lung volumes whether given before or after saline infusion. We speculate from our data that saline infusion has 2 effects on the lung. One is a simple displacement of air by increased intravascular volume producing the reduction in lung volumes. The second is an increase in small airways resistance that is mediated by vagal reflex and blocked with atropine.

[Evaluation of adriamycin cardiotoxicity using equilibrium radionuclide ventriculography. I. Results at rest]

Results of 606 equilibrium radionuclide ventriculographies performed in 348 non-selected patients receiving Adriamycin (ADM) therapy were stored in a data base system. The aim of the study was to assess the influence of a potential cardiotoxic therapy on left ventricular pump function. Increasing ADM doses yielded a significant (p less than 0.05) decrease of the resting ejection fraction (R-gEF), the peak ejection rate and the peak filling rate. End diastolic and end systolic volumes increased significantly. Stroke volume, heart rate and time to peak filling rate did not change significantly. 368 follow-up studies were performed in 128 patients: 65/128 patients presented a decrease of R-gEF, but only in 45 of these patients R-gEF values fell into the pathologic range. In 44 of these follow-ups, R-gEF remained unchanged. In 19 patients, a R-gEF increase was observed. At the beginning of ADM therapy 14% of the patients had subnormal R-gEF values. With increasing ADM doses pathologic findings increased to 86% in patients with ADM doses higher than 500 mg/m2.

[Evaluation of adriamycin cardiotoxicity using equilibrium radionuclide ventriculography. II. Results during exercise]

The aim of the study was to evaluate the influence of a cardiotoxic therapy with Adriamycin (ADM) on left ventricular pump function. In 348 patients with malignant tumors, 606 equilibrium radionuclide ventriculographies (ERNV) were performed. In 90 patients, resting studies (R-ERNV) were followed by studies during exercise (E-ERNV). Results were evaluated statistically to determine whether E-ERNV provides more reliable parameters in the early detection of Adriamycin cardiomyopathy (ADM-CMP) than R-ERNV. The following left ventricular parameters were evaluated: global ejection fraction (gEF); end diastolic, end systolic, stroke volume (EDV, ESV, SV); peak filling rate, peak ejection rate (pFR, pER); time to peak filling rate (TpFR) and heart rate. Increasing ADM doses yielded a significant decrease (p less than 0.05) of resting values of gEF, pER, pFR. In contrast, stress-induced increases of gEF, pER, pFR were found independent of accumulative ADM doses and independent of the resting values of these parameters. An increase of gEF resulted from a significant decrease of ESV. In most cases, pathologic results at rest were detected earlier than subnormal changes of exercise values. Therefore, E-ERNV does not have a significantly higher sensitivity in the early detection of ADM-CMP than R-ERNV and is not required for the surveillance of patients under ADM therapy.

Blood and protein loss via small-intestinal inflammation induced by non-steroidal anti-inflammatory drugs

Nearly three-quarters of patients on long-term treatment with non-steroidal anti-inflammatory drugs (NSAIDs) have small-intestinal inflammation, the consequences of which are largely unknown. Two potentially important complications, blood and protein loss from the small intestine, have been studied. 49 patients on NSAIDs underwent study with an indium-111 labelled leucocyte technique which localises and measures intestinal inflammation. 32 patients underwent simultaneous study with technetium-99m labelled red blood cells (RBC), which showed identical sites of localisation to 111In-leucocytes in 19. Intestinal blood loss was measured in 8 patients by use of chromium-51 labelled RBC, and a significant correlation between blood loss and intestinal inflammation was found. Intestinal protein loss was assessed in 9 patients with 51Cr-labelled proteins; patients with NSAID-induced small-intestinal inflammation were found to have a protein-losing enteropathy. These studies show that small intestinal inflammation caused by NSAIDs is associated with blood and protein loss, both of which may contribute to the general ill-health of rheumatic patients.

Quantification of myocardial injury produced by temporary coronary artery occlusion and reflow with technetium-99m-pyrophosphate

Previously, technetium-99m-stannous pyrophosphate (99mTc-PPi) has been used to localize and estimate the size of myocardial infarcts in animals after permanent coronary artery occlusion. This study tested the hypothesis that 99mTc-PPi accurately sizes myocardial infarctions produced by temporary coronary artery occlusion and reflow in dogs. Three groups of dogs were studied: group A underwent 3 hr of occlusion followed by 2 hr of reperfusion, with 99mTc-PPi injected 10 min after reflow (n = 10); group B underwent 3 hr of occlusion followed by 2 hr of reperfusion, with 99mTc-PPi injected 90 min after reflow (n = 11); and group C underwent 3 hr of occlusion followed by reflow with 99mTc-PPi injected at 10 min and again at 48 hr after reflow (n = 5). Myocardial slices from group A and B dogs were imaged in vitro. Group C dogs were imaged with single photon-emission computed tomography (SPECT) in vivo, and myocardial slices were imaged in vitro at the conclusion of the study. The extent of myocardial infarction was defined with triphenyltetrazolium chloride (TTC) staining, and coronary blood flow was estimated with radioactive microspheres. In addition, transmural myocardial tissue samples were taken from the center of the myocardial infarction, the lateral portion of the myocardial infarction, the normal myocardium adjacent to the lateral aspect of the infarcts, and from the normal myocardium and counted for 99mTc-PPi activity. A significant correlation was found between infarct size determined by areas of increased 99mTc-PPi uptake and that estimated from TTC staining for both group A (r = .89) and group B animals (r = .98).(ABSTRACT TRUNCATED AT 250 WORDS)

[Nuclear medicine in determining the shunt in ductus arteriosus Botalli]

In 9 patients with patent ductus arteriosus, quantification of left-to-right shunt was performed with dye dilution curves after peripheral injection and with radionuclide ventriculography. The study was repeated within 7 days after successful transluminal occlusion of the ductus with an Ivalon-plug. Reproducubility of the method could be studied in one patient in whom reopening of the ductus occurred. Dye dilution curves were analyzed using the method of Carter et al. Radionuclide ventriculography was performed as a combined first-pass and equilibrium study: effective stroke volume was derived from the first pass of the tracer through the heart; during the equilibrium phase left ventricular ejection fraction (EF) and left ventricular enddiastolic volume (EDV) were evaluated. The difference between total left ventricular stroke volume (product of EF and EDV) and effective stroke volume was taken as shunt volume. This volume as a fraction of total left ventricular stroke volume resulted in percent left-to-right shunt. The sensitivity of the dye technique was 78%; a quantification of the shunt lesion was possible in 55% of all cases (shunt greater than 35%). The sensitivity of the radionuclide technique was 90%. The severity of the lesion could not be determined in one patient with a minimal shunt. After successful occlusion of the ductus, dye dilution curves normalized in all cases. Radionuclide ventriculography showed normalization in all but one patient. This patient with concomitant mitral regurgitation still showed moderate left ventricular volume overload.(ABSTRACT TRUNCATED AT 250 WORDS)

[Diagnostic significance of electrocardiography and myocardial scintigraphy with 99m Tc-Sn-pyrophosphate and 99m Tc-Sn-phosphone in patients with stenocardia]

Altogether 123 angina patients were examined using electrocardiography and scintigraphy of the myocardium with two 99m Tc radiopharmaceutical complexes: pyrophosphate and phosphone. A comparative analysis of the results obtained with different methods of investigation before and after an attack of angina pectoris was made. The authors have shown some peculiarities of radionuclide distribution in the myocardium and the diagnostic value of each method of investigation in patients with different clinical forms of angina pectoris.

Effect of Sn(II) ion concentration and heparin on technetium-99m red blood cell labeling

While convenience and economy favor the use of in vivo methods for labeling red blood cells (RBCs) with [99mTc]pertechnetate, previous reports suggested that patient medication such as heparin might interfere and thus result in inferior quality images. In this study, using a canine model, the role of stannous Sn(II) ion in in vivo and in vitro labeling of RBCs both in the presence and absence of a therapeutic dose of heparin was investigated. Our results showed that Sn(II) ion concentration of 20 micrograms/kg body weight levels provided better than 80% in vivo labeling efficiency enabling high quality blood-pool images even in the presence of therapeutic doses of heparin.

Acute and chronic effects of nicardipine on systolic and diastolic left ventricular performance in patients with heart failure: a pilot study

Nicardipine is a new calcium ion antagonist with vasodilating properties which has been shown to be effective in the treatment of hypertension and angina. We have studied its effect on systolic and diastolic left ventricular function in patients with mild to moderate degrees of congestive heart failure. Ten male patients with New York Heart Association Class II and III heart failure underwent acute treatment with an intravenous infusion of nicardipine (10 mg over 10 minutes). A nuclear probe was used to monitor left ventricular ejection fraction, peak filling rate, and relative cardiac output. Blood pressure and heart rate were also measured. The blood pressure (mean +/- SD) fell from 133 +/- 26/86 +/- 11 mmHg to 103 +/- 22/69 +/- 13; the heart rate rose from 67 +/- 9 beats/min to 85 +/- 10; left ventricular ejection fraction from 31 +/- 7 to 38 +/- 6%; relative cardiac output from 24 +/- 9 to 41 +/- 11; peak filling rate from 1.18 +/- 0.4 end-diastolic volume per second to 1.82 +/- 0.4 (p less than 0.001 in all cases) at the end of infusion. After 4 weeks of chronic treatment in eight patients (20 mg to be taken three times daily (tds) in one and 40 mg tds in 7), the blood pressure and heart rate had returned to baseline values but the improvements in left ventricular ejection fraction, relative cardiac output, and peak filling rate were sustained; this was associated with functional improvement in all 8 patients.(ABSTRACT TRUNCATED AT 250 WORDS)

[Results of combined myocardial scintigraphy and radionuclide ventriculography before and after transluminal coronary angioplasty of critical coronary artery stenoses]

This study compares exercise radionuclide ventriculography (RNVG) and exercise myocardial scintigraphy with 201Tl (MSC) both computed trisectorially. 137 patients before and after transluminal angioplasty (TCA) were investigated. While specificity equivalent was set at 90% for both methods (10% percentile of the controls [n = 29]) overall sensitivity for RNVG was 79% (n = 86) and for MSC 78% (n = 98). Sensitivity of RNVG for lesions of the posterior wall was lower than for the anterior wall: LAD stenoses 83% (n = 46), RCA stenoses 71% (n = 17), and LCX stenoses 63% (n = 8). Sensitivity of MSC presents only a slight difference between anterior and posterior wall lesions: LAD stenoses 78% (n = 51), RCA stenoses 73% (n = 22), RCX stenoses 100% (n = 8). Reproducibility of pathological findings before and after non-successful TCA and the determination of the stenosed vessel was slightly better with MSC than with RNVG. Functional improvement after a successful TCA is predictable by MSC, whereas RNVG documents the functional improvement.

Left ventricular dysfunction induced by cold exposure in patients with systemic sclerosis

Raynaud's phenomenon and cardiac abnormalities are frequent in patients with systemic sclerosis. Radionuclide ventriculograms were obtained in 16 patients with Raynaud's phenomenon and systemic sclerosis or the related CREST syndrome and in 11 normal volunteers in order to evaluate changes in left ventricular function that might be induced by exposure to cold. Left ventricular regional wall motion abnormalities developed in nine of 16 patients during cooling compared with only one of 11 control subjects, despite a comparable rise in mean arterial pressure (p less than 0.02). The abnormalities occurred in seven of 11 patients with systemic sclerosis, one of four with CREST syndrome, and one with Raynaud's disease. To test the potential protective effect of nifedipine, radionuclide ventriculograms were then obtained during cooling after sublingual nifedipine (20 mg). Only five of 13 patients had wall motion abnormalities, and the severity of the abnormalities was significantly less than during the first cooling period (p = 0.03). Five of eight patients who had cold-induced wall motion abnormalities during the first cooling period had none after nifedipine, whereas two other patients demonstrated small abnormalities only during the second cooling period after treatment with nifedipine. It is concluded that cold induces segmental myocardial dysfunction in patients with systemic sclerosis and that nifedipine may blunt the severity of this abnormal response.

HPLC separated fractions of 99mTc(NaBH4)-HEDP as myocardial infarct imaging agents

Component fractions of 99mTc(NaBH4)-HEDP mixtures, isolated by anion exchange high performance liquid chromatography (HPLC), have been evaluated as myocardial infarct imaging agents in two animal models. Results from both the isoproterenol-induced myocardial infarction model, and the heat-induced myocardial necrosis model, show that the several HPLC isolated components exhibit significantly different abnormal/normal heart uptake ratios. In addition, the HPLC isolated component of shortest chromatographic retention time exhibits a higher abnormal/normal heart uptake ratio than does 99mTc(Sn)-PyP, the current agent of choice for clinical myocardial infarct imaging.

[Unsolved problems of the diagnosis of acute focal dystrophy and microfocal myocardial infarction]

The use of up-to-date diagnostic methods and the estimation of the extent of myocardial lesion in patients with intermediate coronary conditions (serial assays of CPK and MV-CPK activity with subsequent computation of the weight of affected myocardium, ECTG and myocardial 99mTc-Sn-pyrophosphate scintigraphy using a gamma-counter) demonstrated: the presence of necrotic foci in patients with acute focal myocardial dystrophy; a considerable variation in the weight of affected myocardium; and high diagnostic value of ECTG for the assessment of the extent of myocardial lesion in patients with intermediate coronary conditions. Objective criteria have been worked out for the differential diagnosis of various intermediate coronary conditions.

Early positive technetium-99m stannous pyrophosphate images as a marker of reperfusion after thrombolytic therapy for acute myocardial infarction

Fourteen patients with transmural acute myocardial infarction (AMI) were treated with intravenous streptokinase a mean of 4 +/- 1 hours after chest pain and underwent technetium-99m stannous pyrophosphate (Tc-99m-PPi) imaging 7 +/- 2 hours after the onset of chest pain. The early Tc-99m-PPi images were obtained to test the hypothesis that an early, strongly abnormal Tc-99m-PPi image suggests reperfusion. Eleven of 14 patients had early peaking (within 16 hours) serum creatine kinase isoenzyme levels (CK-B) at a mean of 11 +/- 3 hours. Ten of 14 patients had 3+ or 4+ acute Tc-99m-PPi images. Eight of 11 patients had patent infarct-related vessels at cardiac catheterization 15 days after AMI. One patient who had both an early positive Tc-99m-PPi image and CK-B peak level had an occluded infarct-related artery at catheterization. Acute left ventricular (LV) ejection fraction (EF) by radionuclide ventriculography was compared with LVEF on day 15, and improved from 0.37 +/- 0.13 to 0.50 +/- 0.16 (p = 0.004) in the 10 patients with strongly positive acute Tc-99m-PPi images. LVEF also improved from 0.37 +/- 0.12 to 0.49 +/- 0.15 (p = 0.003) in the 11 patients with early peaking serum CK-B values. Three patients without evidence of reperfusion failed to improve the LVEF from the initial value to the one obtained at hospital discharge. Six control patients had acute Tc-99m-PPi images 10 +/- 2 hours after chest pain; none had strongly positive acute Tc-99m-PPi images, and the mean time to peak CK-B was 19 +/- 5 hours.(ABSTRACT TRUNCATED AT 250 WORDS)

Comparison of technetium-99m pyrophosphate and technetium-99m methylene diphosphonate with variable amounts of stannous chloride in the detection of acute myocardial infarction

The authors prospectively compared the ability of Tc-99m pyrophosphate (PYP) and Tc-99m methylene diphosphonate (MDP) to detect acute myocardial infarctions. The agents used were PYP (12 mg) with 3.4 mg of stannous chloride, MDP (10 mg) with 1.0 mg of stannous chloride, and MDP (10 mg) with 3.4 mg of stannous chloride. Imaging was performed on three consecutive days on 34 patients with proven myocardial infarctions, using the same agent on the first and third days of the study and an alternate agent on the second day. Agents were assigned randomly to each of six groups of patients. First images were obtained an average of 3.7 days (range, one to six days) following myocardial infarction. Seventeen of 23 patients (75%) had images positive for acute myocardial infarction with Tc-99m PYP, whereas only two of 21 patients (9.5%) had positive studies with Tc-99m MDP with 3.4 mg of stannous chloride and one of 24 patients (4.2%) had positive studies with Tc-99m MDP and 1.0 mg of stannous chloride. All three myocardial infarctions detected by Tc-99m MDP were extensive and transmural. When MDP and PYP were both positive in the same patient, the apparent size of the myocardial infarction was much smaller with the MDP. It is concluded that MDP can detect only large myocardial infarctions, has poor localization in the infarcted tissue, and varying the stannous chloride content of the preparation does not improve the ability of MDP to detect acute myocardial infarctions.

Postcountershock myocardial damage after pretreatment with adrenergic and calcium channel antagonists in halothane-anesthetized dogs

Transthoracic electric countershock can cause necrotic myocardial lesions in humans as well as experimental animals. The authors investigated the effect on postcountershock myocardial damage of pretreatment with prazosin (0.1 mg/kg), an alpha-1 antagonist; L-metoprolol (0.5 mg/kg), a beta-1 antagonist, and verapamil (0.5 mg/kg), a calcium channel-blocking agent. Twenty dogs were anesthetized with halothane and given two transthoracic countershocks of 295 delivered joules each after drug or vehicle treatment. Myocardial injury was quantitated 24 h following countershock by measuring the uptake of technetium-99m pyrophosphate in the myocardium. Elevated technetium-99m pyrophosphate uptake occurred in visible lesions in most dogs regardless of drug treatment. For each of four parameters of myocardial damage there was no statistically significant difference between control animals and those treated with prazosin, metoprolol, or verapamil. These data suggest that adrenergic or calcium channel-mediated mechanisms are not involved in the pathogenesis of postcountershock myocardial damage.

A prospective study of myocardial damage in electrical injuries

A prospective study was undertaken to determine the incidence of possible myocardial damage following electrical injury. Sixteen patients with non-flash electrical injuries were assessed utilizing serial electrocardiograms (ECG), creatine kinase (CK) and MB creatinine kinase (MB-CK) determinations, technetium 99m stannous pyrophosphate scans, and 24-hour Holter monitors. Results showed that five patients (31%) had abnormal ECG, nine patients (56%) had elevations of the MB-CK isoenzyme, and one patient had a transiently abnormal Holter monitoring. No patient had an abnormal technetium pyrophosphate cardiac scan. Of the nine patients with elevated MB-CK levels, only two had abnormal ECG. None of the patients had clinical evidence of cardiac dysfunction. These results indicate a poor correlation of elevated MB-CK levels with ECG abnormalities, and demonstrate a relatively low incidence of myocardial damage in association with electrical injuries.

[Effect of body loading on the specific blood radioactivity following 99mTc in-vivo erythrocyte labelling. The effects on determining end-diastolic volume in equilibrium radionuclide ventriculography]

In 40 patients who underwent stress-equilibrium-radionuclide-ventriculography, we examined the stress-induced change of blood radioactivity concentration. A significant (p less than 0.025) increase of blood radioactivity concentration after peak exercise (mean +7.2%) was found. This increase was the result of a significant (p less than 0.025) increase of the hematocrit (mean +4.7%) due to a decrease of the plasma volume. The changes of radioactivity concentration and hematocrit neither show any correlation with peak exercise value, integral exercise or duration of exercise, nor with the increase of heart rate or blood pressure. The increase of end-diastolic volume appears to result largely from a stress-induced increase of blood radioactivity concentration. Thus, radioactivity concentration should be measured before and after exercise when evaluating volume changes caused by stress-equilibrium-radionuclide-ventriculography.

Technetium-99m labeling of polymorphonuclear leukocytes: preparation with two different stannous agents

A technique for in vitro labeling of human polymorphonuclear leukocytes with Tc-99m is described. Titration of stannous fluoride and stannous pyrophosphate concentrations for pretinning was performed, and optimal amounts of the stannous agents were added to polymorphonuclear leukocytes efficiently isolated from 100 ml of blood. Labeling with 10-15 mCi Tc-99m resulted, after three washings of cell suspensions, in yields of 1.6-4.8 mCi, corresponding to 20.5-33.5% of added tracer. Cell-bound activity in the final cell suspensions was 92.3% +/- 1.9 of the added dose. Cell function was not impaired by the labeling technique. Sterility and exclusion of bacterial endotoxins in the final cell suspensions were demonstrated. The method may prove of diagnostic value in the isolation, labeling, and reinjection of autologous leukocytes for scintigraphic imaging of acute inflammatory lesions.

Blood volume in the rat

The organ distribution of radiopharmaceuticals in the rat is usually estimated using 7% of body weight (BW) for blood volume (BV). In spite of its important impact on the evaluation of new agents, this value has not been validated adequately. We therefore studied blood volume in 70 awake Wistar rats (100 to 400 g BW) in which red blood cell volume (RBCV) and plasma volume (PV) were measured simultaneously. Red blood cell volume was measured by in vitro RBC-tagging with Tc-99m in Sn-pyrophosphate, 0.05 microgram per ml of blood; plasma volume was measured with I-125 human serum albumin (HSA). Ten minutes after injection of the dose, 0.5 ml of blood was withdrawn from the carotid or femoral artery and duplicate samples of 0.025 ml of blood were counted after separating RBCs from plasma. Total blood volume was calculated by adding RBC volume and plasma volume. The relationship for the entire group was: BV (ml) = 0.06 X BW + 0.77 (r = 0.99, n = 70, p less than 0.001). The difference between male and female rats was not statistically significant. The use of an arbitrary value of 7% for estimation of blood volume can lead to significant errors in calculating radiopharmaceutical distribution. The use of the general formula for the blood-volume calculation described here should improve the accuracy and reliability of estimates of radiopharmaceutical distribution.

Pseudoaneurysm of the left ventricle. Diagnosis by first pass scintigraphy

False aneurysm of the left ventricle is a rare complication of myocardial infarction with a high propensity for late rupture. Timely diagnosis is important and surgical repair is curative in a high percentage of patients. A case in which a false left ventricular aneurysm was recognized by first pass radionuclide angiography and confirmed by contrast ventriculography is reported. Surgery was then performed successfully. The diagnosis of false left ventricular aneurysm using radionuclide angiography, as well as other diagnostic imaging modalities, is discussed.

Silent acute myocardial infarction masked by transient WPW syndrome

A case with transient WPW syndrome during silent acute myocardial infarction is presented. Although the clinical picture and laboratory data were non contributory and the surface electrocardiogram showed delta and not Q waves, myocardial perfusion scintigraphy showed typical area of acute necrosis. Abnormal accessory connections probably occur or latent such pathways become functional during acute myocardial ischemia.

[Quantitative resting radionuclide-ventriculography for multifactorial analysis of left ventricular function]

Results from 388 patients, examined with quantitative equilibrium radionuclide ventriculography (qERNV) at rest, were stored in a data bank system and evaluated statistically. The value of time and velocity parameters [ejection time (ET), filling time (FT), time ES to peak filling rate (TpFR), mean (mER) and peak (pER) ejection rate, peak filling rate (pFR)] were evaluated in patients with coronary heart disease (CHD, with and without history of earlier myocardial infarction) or with cardiomyopathy (CMP). Significant (p less than 0.025) changes vs. normal in CHD I/II were obtained from pER, pFR, ET, in CHD III from gEF, EDV, mER, pER, pFR, in CHD IV from gEF, EDV, mER, pER, pFR, in patients with infarction or with CMP from gEF, EDV, mER, pER, pFR, ET and TpFR. Resting qERNV revealed a sensitivity in diagnosing a CHD (stages I-III) by mER of 30-59%, by pER of 40-65%, by pFR of 48-60% and by ET of 58-61%, which was higher than the sensitivity of gEF (19-56%).

In vivo labelling of RBC with 99mTc for blood pool imaging using different stannous radiopharmaceuticals

The in vivo 99mTc-RBC labelling efficiency and stability of labelling was assessed after pretinning with a high-stannous content DTPA kit (Sn DTPA) in comparison with Sn-pyrophosphate (Sn PPi) and a low-stannous DTPA kit (DTPA). The distribution in Sprague Dawley rats showed that similar fractions of administered 99mTc remained within the blood pool after pretinning with Sn DTPA and Sn PPi when equal quantities of stannous ions (15 micrograms/kg) and equal time intervals (30 min) between successive IV injections of pretinning agent and 99mTc-pertechnetate were used. Significantly lower fractions were found when DTPA (1.9 micrograms Sn2+/kg) was used for pretinning. The rate of 99mTc elution emphasises the importance of the Sn2+ concentration used, not only for labelling efficiency but also for stability of the labelling. Satisfactory intravascular activity, exceeding 80% during the first hour post-injection, was demonstrated in three volunteers after 99mTc injection, when Sn DTPA was used for pretinning. Left ventricular ejection fractions (LVEF) measured by equilibrium radionuclide angiography after pretinning with Sn DTPA in 24 patients correlated well (r = 0.98) with those obtained by contrast angiographies over a broad spectrum of values (0.14-0.72). Four repeated LVEF measurements at 45-min intervals in six additional patients at rest showed excellent reproducibility in each patient: maximum variation was less than 6%.

A clinical evaluation of the RNCA study using Fourier filtering as a preprocessing method

Forty-one patients (25 male, 16 female) were studied by RNCA in our institution. There were 42 rest studies and 24 stress studies (66 studies total). Sixteen patients were normal, 15 had ASHD, seven had a cardiomyopathy, and three had left-sided valvular regurgitation. Each study was preprocessed using both the standard nine-point smoothing method and Fourier filtering. Amplitude and phase images were also generated. Both preprocessing methods were compared with respect to image quality, border definition, reliability and reproducibility of the LVEF, and cine wall motion interpretation. Image quality and border definition were judged superior by the consensus of two independent observers in 65 of 66 studies (98%) using Fourier filtered data. The LVEF differed between the two processes by greater than .05 in 17 of 66 studies (26%) including five studies in which the LVEF could not be determined using nine-point smoothed data. LV wall motion was normal by both techniques in all control patients by cine analysis. However, cine wall motion analysis using Fourier filtered data demonstrated additional abnormalities in 17 of 25 studies (68%) in the ASHD group, including three uninterpretable studies using nine-point smoothed data. In the cardiomyopathy/valvular heart disease group, ten of 18 studies (56%) had additional wall motion abnormalities using Fourier filtered data (including four uninterpretable studies using nine-point smoothed data). We conclude that Fourier filtering is superior to the nine-point smooth preprocessing method now in general use in terms of image quality, border definition, generation of an LVEF, and cine wall motion analysis. The advent of the array processor makes routine preprocessing by Fourier filtering a feasible technologic advance in the development of the RNCA study.

Fourier amplitude and phase analysis in the clinical evaluation of patients with cardiomyopathy

Fifty-four patients with a cardiomyopathy were studied by RNCA and Fourier amplitude and phase image analysis. The study group included patients with ischemic cardiomyopathy (27) and an equal number of patients with a primary cardiomyopathy: drug-induced (22), idiopathic (three), radiation-induced (one), and amyloidosis (one). Twenty-eight patients had rest studies alone and 26 had both rest and stress studies (80 total). The mean rest LVEF in the ischemic group was 27.9%, in the drug-induced group 36.5%, and in the idiopathic group 30%. The stress LVEF decreased in 92% of patients with ischemic cardiomyopathy and 45% of patients with primary (drug-induced) cardiomyopathy. Fourier amplitude and phase images were generated for each study. Amplitude and phase images were abnormal in all patients with an ischemic cardiomyopathy. LV amplitude abnormalities were regional and phase was directional. A zone of dysynergy on phase analysis was present in 44% of patients with ischemic cardiomyopathy. In the drug-induced primary cardiomyopathy group, all patients had abnormal amplitude and 86% had abnormal phase. Amplitude abnormalities were global rather than regional and phase patterns were nondirectional. Only one patient had a zone of dysynergy on the phase image. We conclude that the stress LVEF alone cannot consistently differentiate between ischemic and primary cardiomyopathies and that Fourier amplitude and phase analysis may be useful in determining the etiology of a cardiomyopathy (ischemic vs primary).