Quantitative angiographic analysis of right ventricular global function in normal incidences and in patients with coronary artery disease.

At present right ventriculography data cannot be accurately estimated owing to the absence of software for quantitative analysis of the right ventricle (RV) volumes and function. The aim of this study was to use existing software for left ventriculography analysis to estimate right ventricular volumes and function in patients without coronary lesions and in those with coronary artery disease (CAD). Thirty-two patients without significant lesions of coronary arteries and 20 patients with CAD were examined with left ventriculography and right atriography. Each examination was performed in 2 projections: 30 degrees right anterior oblique (RAO 30 degrees) and 60 degrees left anterior oblique (LAO 60 degrees) projections. Correction factor (CF) was obtained by finding the ratio between stroke volumes of the left and right ventricles. The mean CF was 0.9243+/-0.2887 for patients without CAD and 0.8758+/-0.2232 for patients with CAD. Such calculation is the easiest and quite accurate method of determining RV volumes and function by using existing software of quantitative angiographic analysis.

Pulmonary blood flow distribution in stage 1 chronic obstructive pulmonary disease.

We investigated the hypothesis that lung blood flow distribution is modified in stage 1 chronic obstructive pulmonary disease (COPD). We compared patients with stage 1 COPD (n = 11) with restrictive patients with comparable blood gases (n = 7), to patients with low cardiac index with normal lungs (n = 11) and to control subjects (n = 11). Distribution of transit time (DTT) was computed by deconvolution from first pass radioactivity curves (albumin (99m)Tc) reconstructed from right and left ventricular regions of interest. Distribution descriptors, mean transit time (p < 0.05), standard deviation (p < 0.001), relative dispersion (p < 0.001), and kurtosis (p < 0.001) differed between groups (ANOVA). Cardiac index was the same in COPD and low CI groups but lower compared with normal subjects (p < 0.05). After normalization for cardiac output, the DTT of patients with COPD remained different from low CI and restrictive patients (p < 0.001). Therefore changes in DTT in patients with COPD compared with patients without COPD could not be explained on the basis of difference in cardiac output. Because P(O(2)), PC(O(2)), and pH were similar in COPD and restrictive groups, difference in distribution could not be explained either on the basis of blood gas data. We conclude that changes in DTT occurs in stage 1 COPD and cannot be explained by hypoxemia, hypercapnia, or acidosis alone but must relate to other structural or regulatory responses.

Combined left ventricular wall motion and myocardial perfusion stress imaging in the initial assessment of patients with a recent uncomplicated myocardial infarction.

UNLABELLED: The aim of the study was to examine the ability to simultaneously assess left ventricular function and myocardial perfusion by using a single injection of technetium-99m sestamibi at rest and during submaximal exercise to identify high-risk patients with left main, proximal left anterior descending (LAD), or three-vessel coronary artery disease (CAD) after an uncomplicated acute myocardial infarction (AMI). Multiple studies have evaluated the separate value of the exercise ECG, myocardial perfusion scintigraphy, and radionuclide angiocardiography (RNA) for identifying patients with severe CAD. The availability of technetium-99m (Tc99m)-labeled myocardial imaging agents offers the opportunity to evaluate simultaneously ventricular function and myocardial perfusion during a single exercise session. Only limited data are available about the value of this combined technique in the workout of patients early after an uncomplicated AMI. Combined first-pass RNA and myocardial perfusion tomoscintigraphy (SPECT) at rest and during submaximal exercise were performed in 52 patients, less than six weeks after an uncomplicated AMI, with use of Tc99m sestamibi. Patients were classified in two subgroups according to the presence of left main, proximal LAD, or three-vessel CAD. Stepwise logistic regression analysis was used to determine the independent predictors of severe CAD. All patients underwent the exercise testing without any medical complication. On univariate analysis, the global left ventricular ejection fraction (LVEF), wall motion score, and myocardial perfusion score, both at rest and at submaximal exercise, were significantly associated with the presence of severe CAD. The response of LVEF to exercise, and the presence of exercise-induced wall motion or myocardial perfusion abnormalities, were not associated with the severity of CAD. On multivariant analysis only the wall motion score during exercise was an independent predictor for the presence of severe CAD (P < 0.001, r = 0.6). In analyzing patients with anterior AMI separately, LVEF at submaximal exercise was the most accurate predictive parameter. If a cutoff value of 40% was chosen, the LVEF at exercise had a sensitivity of 85% and a specificity of 78% for the detection of severe CAD. In patients with inferior AMI, neither LVEF nor wall motion or myocardial perfusion scores were useful for differentiating the two subgroups. In these patients the presence of an additional perfusion defect during exercise in one of the anterior wall segments yielded a sensitivity of 70% and a specificity of 75% for the presence of severe CAD. IN CONCLUSION: simultaneous evaluation of LV function and myocardial perfusion at submaximal exercise, using a single injection of Tc99m-sestamibi, is a safe and accurate technique for selecting patients with severe CAD after an uncomplicated AMI.

Thallium-201 lung uptake and peak treadmill exercise first-pass ejection fraction.

Increased thallium-201 lung uptake immediately after exercise has been shown (1) to be a marker for extensive coronary artery disease, (2) to correlate with low rest and exercise left ventricular ejection fraction by supine gated blood pool scintigraphy, and (3) to be a powerful independent predictor of future cardiac events. Exercise left ventricular ejection fraction measured during upright exercise by the first-pass technique has also been shown to be a powerful independent prognostic variable. Combined perfusion and exercise left ventricular ejection fraction can be acquired by using the technetium 99m-based myocardial perfusion agents and offers an alternative protocol to stress/redistribution thallium imaging. It is therefore clinically important to understand the relation between exercise lung heart thallium uptake and exercise left ventricular ejection fraction. Accordingly, both these measurements were acquired in 38 patients with documented coronary artery disease who underwent two treadmill exercise studies. Parameters obtained from the first-pass study that are known to affect lung thallium uptake were correlated with exercise lung/heart thallium ratios; lung/heart ratios were used in a model to predict exercise left ventricular ejection fraction values. Exercise left ventricular ejection fraction and peak filling rate showed significant negative correlations with thallium lung/heart ratio, but the first-pass variables examined were not independently predictive of thallium lung uptake. The chance of finding an abnormal thallium lung/heart ratio at exercise LVEF of 40% is only 52%, whereas the chance of finding an abnormal ratio at exercise LVEF of 30% is 74%.(ABSTRACT TRUNCATED AT 250 WORDS)

Evaluation of coronary artery disease using technetium-99m-sestamibi first-pass and perfusion imaging with dipyridamole infusion.

UNLABELLED: The aims of this study were: (1) to test whether first-pass radionuclide angiocardiography (FPRNA) adds useful information to perfusion scintigraphy; and (2) to assess the relative accuracy of perfusion and functional imaging in combination with dipyridamole for the evaluation of CAD. METHODS: Thirty patients with angiographically proven CAD (17 with prior infarction) were studied on separate days at rest and with dipyridamole infusion (0.7 mg/kg over 4 min). Tomographic images were evaluated using an uptake score. Dipyridamole FPRNA was considered positive in case of stress-induced wall motion abnormality or ejection fraction decrease. RESULTS: The CAD detection rate of perfusion imaging was 100%, while that of FPRNA was 70% using wall motion criteria, 63% using ejection fraction response and 77% considering any abnormality. For CAD localization, perfusion imaging showed 76% sensitivity, 96% specificity and 82% accuracy. FPRNA results were 50%, 100% and 60%, respectively. Perfusion imaging was significantly superior to FPRNA also excluding from the analysis the infarct-related vessels. FPRNA did not identify multivessel CAD, which was correctly detected by perfusion imaging in most cases. Both techniques were more sensitive in case of > or = 90% stenosis, but the difference was more remarkable for FPRNA (sensitivity 65% versus 14%, p < 0.0005). CONCLUSIONS: Dipyridamole FPRNA did not add noteworthy clinical information to perfusion imaging regarding CAD detection and evaluation of disease extent. The main contribution of a positive FPRNA was its relation with coronary obstruction severity. These results confirm the superiority of perfusion over functional imaging in combination with coronary vasodilators.

First-pass ventricular ejection fraction using a single-crystal nuclear camera.

UNLABELLED: The purpose of the study was to evaluate the reliability of ejection fractions obtained from first-pass radionuclide ventriculography with a large field-of-view tomographic single-crystal gamma camera. METHODS: A SPECT camera had its electronics redesigned to improve counting efficiency and was equipped with an experimental ultra-high sensitivity collimator. Left ventricular ejection fraction (LVEF) was measured in 28 patients by 30 degrees RAO first-pass imaging and by "best septal view" LAO planar equilibrium radionuclide ventriculography on a conventional small field of view Anger camera. For 28 other patients, first-pass ejection fractions were compared to multicrystal gamma camera values. Visual analysis was performed to judge clinical acceptability of first-pass images for identification of wall-motion abnormalities. RESULTS: Linear regression analysis of first-pass against equilibrium ejection fraction demonstrated good correlation (r = 0.92; slope = 0.90; intercept = 3.8; s.e.e. = 6.4%). First-pass ejection fraction values also correlated linearly with multicrystal camera values for the left ventricle (r = 0.94; slope = 1.05; intercept = 1.3; s.e.e. = 5.3%). For a subgroup of 19 patients, single-crystal camera right ventricle ejection fraction demonstrated good correlation with multicrystal camera values (r = 0.82; slope = 1.15; intercept = 1.3; s.e.e. = 6.1%). Interobserver variability correlated as r = 0.99 for LVEF ejection fraction and r = 0.92 for RVEF. Chi-square analysis of single-crystal first-pass image visual scores versus those from the gated equilibrium acquisitions showed close agreement (p < 10(-8)). CONCLUSIONS: The evaluated camera/collimator system measured left and right ventricular ejection fraction accurately. Lung frame correction and dual regions were superior to paraventricular background correction and a fixed end-diastolic region.

A survey of nuclear cardiological practice in Great Britain. The British Nuclear Cardiology Group.

There is little information on the practice of nuclear cardiology in Great Britain. On behalf of the British Nuclear Cardiology Group in October 1988 we sent a postal questionnaire to 143 hospitals with nuclear medicine facilities (at least 70% of such hospitals). Sixty nine replies were received (48%), of which 23 (33%) were from teaching hospitals and 46 (39%) non-teaching. In these hospitals 147,904 isotope investigations were performed annually (mean 2311 per centre) of which 17,298 (12%) (mean 254 per centre) were cardiac studies. Of these, 59% were equilibrium radionuclide ventriculograms, 14% first pass ventriculograms, and 27% thallium-201 scans. Rest studies were performed more commonly by radiographers or technicians (63%) than by doctors (20%), but doctors were more commonly involved in stress studies (48%). Radiologists reported the studies more often (28%) than they performed them (6%). Methods of acquisition and analysis were varied and, for instance, the lower limit of normal left ventricular ejection fraction ranged from 35% to 75% (mean 49%). For thallium imaging 42% of centres used dipyridamole in some patients and 24% used tomography. These data show that nuclear cardiology techniques are used much less frequently in Great Britain than in countries such as the United States and Germany, that the ratio of blood pool to myocardial perfusion imaging is much higher than elsewhere, and that methods are poorly standardised. They may provide the impetus to improve the service and serve as a baseline for future surveys.