Normalised radionuclide measures of left ventricular diastolic function

Abnormal left ventricular diastolic function is being increasingly recognised in patients with clinical heart failure and normal systolic function. A simple routine radionuclide measure of diastolic function would therefore be useful. To establish this, the relationship of peak diastolic filling rate (normalized for either end diastolic volume, stroke volume, or peak systolic emptying rate), and heart rate, age, and left ventricular ejection fraction was studied in 64 subjects with normal cardiovascular systems using routine gated heart pool studies. The peak filling rate, when normalized to end diastolic volume, correlated significantly with heart rate, age and left ventricular ejection fraction, whereas normalization to stroke volume correlated significantly to heart rate and age but not to left ventricular ejection fraction. Peak filling rate normalized for peak systolic emptying rate correlated with age only. Multiple regression equations were determined for each of the normalized peak filling rates in order to establish normal ranges for each parameter. When using peak filling rate normalized for end diastolic volume or stroke volume, appropriate allowance must be made for heart rate, age and ejection fraction. Peak filling rate normalized to peak ejection rate is a heart rate independent parameter which allows the performance of the patient's ventricle in diastole to be compared with its systolic function. It may be used in patients with normal systolic function to serially follow diastolic function or if age corrected, to screen for diastolic dysfunction.     

Point by Point Examination of the equilibrium gated radionuclide left ventricular time activity curve; validation by biplane angiography

Examination of the time course of left ventricular ejection has been found useful in several clinical applications. Equilibrium gated radionuclide angiography provides non-invasive means to obtain the ventricular ejection curve. To evaluate the accuracy of the equilibrium gated radionuclide left ventricular volume curve we compared equilibrium gated radionuclide date with biplane cine-angiography in 16 patients examining each set of data on a point by point basis. The cine-angiographic data consisted of 60 frame per second biplane cineangiograms and the radionuclide data consisted of 28 points spanning the cardiac cycle. All data was normalized for the patient's heart rate and stroke volume. The equilibrium gated radionuclide angiographic data accurately reproduced the contrast angiographic data at each point on the curve. This result justifies using the equilibrium gated radionuclide time activity curve to evaluate parameters such as early systolic ejection rates or rates of maximum ventricular ejection.     

Point by point examination of the equilibrium gated radionuclide left ventricular time activity curve: Validation by biplane angiography

Examination of the time course of left ventricular ejection has been found useful in several clinical applications. Equilibrium gated radionuclide angiography provides non-invasive means to obtain the ventricular ejection curve. To evaluate the accuracy of the equilibrium gated radionuclide left ventricular volume curve we compared equilibrium gated radionuclide data with biplane cine-angiography in 16 patients examining each set of data on a point by point basis. The cine-angiographic data consisted of 60 frame per second biplane cineangiograms and the radionuclide data consisted of 28 points spanning the cardiac cycle. All data was normalized for the patient's heart rate and stroke volume. The equilibrium gated radionuclide angiographic data accurately reproduced the contrast angiographic data at each point on the curve. This result justifies using the equilibrium gated radionuclide time activity curve to evaluate parameters such as early systolic ejection rates or rates of maximum ventricular ejection.     

Haemodynamic effects of dual-chamber pacing versus ventricular pacing during a walk test in patients with depressed or normal left ventricular function

Purpose Dual-chamber rate-modulated pacing provides haemodynamic benefits compared with ventricular pacing at rest, but it is unclear whether this also holds true during physical exercise in patients with heart failure. This study assessed the haemodynamic response to a walk test during dual-chamber pacing and ventricular pacing in patients with depressed or normal left ventricular (LV) function.Methods Twelve patients with an LV ejection fraction <50% and 11 patients with an LV ejection fraction 50% underwent two randomised 6-min walk tests under dual-chamber rate-modulated pacing and ventricular pacing at a fixed rate of 70 beats/min. All patients had a dual-chamber pacemaker implanted for complete heart block. LV function was monitored by a radionuclide ambulatory system.Results In patients with depressed LV function, the change from dual-chamber pacing to ventricular pacing induced a decrease in end-systolic volume at the peak of the walk test (P<0.05), with no difference in end-diastolic volume. As a consequence, higher increases in LV ejection fraction (P<0.0001) and stroke volume (P<0.01) were observed during ventricular pacing. No difference in cardiac output was found between the two pacing modes. In patients with normal LV function, the change from dual-chamber pacing to ventricular pacing induced a significant decrease in cardiac output (P<0.005 at rest and P<0.05 at the peak of the walk test).Conclusion Compared with dual-chamber rate-modulated pacing, ventricular pacing improves cardiac function and does not affect cardiac output during physical activity in patients with depressed LV function, whereas it impairs cardiac output in those with normal function.     

Left ventricular function and the distribution of pulmonary and total blood volume in hypertensive and normotensive man

Using radionuclide methods the relationship between total and central blood volume and left ventricular function was studied in 12 patients with untreated essential hypertension and contrasted with the findings in eight normotensive subjects. The principal findings were of an increased stroke volume and end-diastolic volume with an increase in the ratio of pulmonary to total blood volume in the hypertensive patients. Left ventricular ejection fraction was similar in both groups but end-systolic volume was increased presumably in response to the increased afterload of the ventricle. The increased pulmonary blood volume may be secondary to altered left ventricular mechanics and not a primary determinant of cardiac function.     

Ambulatory monitoring of left ventricular function with a radionuclide detector system]

The recent development of new radionuclide detectors allows noninvasive outpatient monitoring of left ventricular function. This study was aimed at describing a new radionuclide technique useful to monitor cardiac function and at evaluating its potential clinical applications. We studied 14 normal subjects, 30 patients with coronary artery disease and 25 patients with dilated cardiomyopathy. Left ventricular function was continuously monitored in control conditions at rest, during daily physical activity of different intensity (walking on a level surface and climbing stairs), and during bicycle exercise. Left ventricular ejection fraction (EF) variability during recording in control conditions at rest was 0.2 +/- 1.8%. A significant relationship between outpatient EF at rest and conventional equilibrium radionuclide angiography was observed (r = 0.97, n = 69, p less than 0.001). In normal subjects both daily physical activity and exercise stress test induced an increase in heart rate and EF. In patients with coronary artery disease and in patients with dilated cardiomyopathy a heterogeneous EF response was observed during physical activity and exercise stress test. Our results demonstrate that this technique can be used for the ambulatory monitoring of left ventricular function in both normal subjects and patients with different types of cardiomyopathies.     

Electrocardiograph-gated single photon emission computed tomography radionuclide angiography presents good interstudy reproducibility for the quantification of global systolic right ventricular function

BACKGROUND: Electrocardiograph-gated single photon emission computed tomography (SPECT) radionuclide angiography provides accurate measurement of right ventricular ejection fraction and end-diastolic and end-systolic volumes. AIM: In this study, we report the interstudy precision and reliability of SPECT radionuclide angiography for the measurement of global systolic right ventricular function using two, three-dimensional volume processing methods (SPECT-QBS, SPECT-35%). These were compared with equilibrium planar radionuclide angiography. METHODS: Ten patients with chronic coronary artery disease having two SPECT and planar radionuclide angiography acquisitions were included. RESULTS: For the right ventricular ejection fraction, end-diastolic volume and end-systolic volume, the interstudy precision and reliability were better with SPECT-35% than with SPECT-QBS. The sample sizes needed to objectify a change in right ventricular volumes or ejection fraction were lower with SPECT-35% than with SPECT-QBS. The interstudy precision and reliability of SPECT-35% and SPECT-QBS for the right ventricle were better than those of equilibrium planar radionuclide angiography, but poorer than those previously reported for the left ventricle with SPECT radionuclide angiography on the same population. CONCLUSION: SPECT-35% and SPECT-QBS present good interstudy precision and reliability for right ventricular function, with the results favouring the use of SPECT-35%. The results are better than those of equilibrium planar radionuclide angiography, but poorer than those previously reported for the left ventricle with SPECT radionuclide angiography. They need to be confirmed in a larger population.     

Radionuclide angiography of the heart in coronary heart disease: Where do we stand?

Regional systolic left ventricular performance after myocardial infarction was assessed from 216 radionuclide angiograms performed in 170 patients. Recording of first transit of an intravenously injected bolus of technetium-99m pertechnetate was made by a multicrystal scintillation camera at a framing rate of 20 per second. The RAO view was used and a simultaneous ECG was employed. Statistics adequate for resolving regional events were obtained by a compact bolus input and phasic summation into one representative cycle of data obtained during left ventricular passage. Emphasis was given to imaging of regional systolic left ventricular function: perimeter images of end-systole and end-diastole, regional stroke volume images and ejection fraction images were processed. New trend images are presented that reflect total systolic contraction and improve image quality: regional rate of decrease and increase images, wall motion trend images and regional mean transit time images. In 96% of the cases, correspondence was found between the electrocardiographic location of the infarct and the region of major wall motion and ejection disorder. Akinesia and/or dyskinesia were seen in 77% of the cases; a ventricular aneurysm was found in 11%. Additional areas of wall motion anomalies were shown by 70%. Image analysis, nuclear image signs and their diagnostic meaning, as well as the indications for this nontraumatic examination in coronary heart disease are discussed. Relevant information for medical or surgical therapy can be obtained from early and follow-up studies in patients with unstable, progressive angina, ischemic electrocardiographic signs and those who have had myocardial infarctions.     

Improved left ventricular function after growth hormone replacement in patients with hypopituitarism: Assessment with radionuclide angiography

Prolonged growth hormone deficiency (GHD) leads to marked cardiac dysfunction; however, whether reversal of this abnormality may be achieved after specific replacement therapy has not yet been completely clarified. Fourteen patients with childhood-onset GHD (nine men and five women, mean age 27±4 years) and 12 normal control subjects underwent equilibrium radionuclide angiography under control conditions at rest. Patients with GHD were also studied 6 months after recombinant human (rh) GH treatment (0.05 IU/kg per day). Normal control subjects and patients with GHD did not differ with respect to age, gender and heart rate. In contrast, left ventricular ejection fraction (53%±9% vs 66%±6%,P <0.001), stroke volume index (41±11 vs 51±8 ml/m²,P <0.01) and cardiac index (2.8±0.6 vs 3.±0.51/min/m²,P <0.001) were significantly lower in GHD patients than in normal control subjects. None of the GHD patients showed adverse or side-effects during rhGH therapy; thus none required a reduction in GH dose during the treatment period. Heart rate and arterial blood pressure were not significantly modified by rhGH treatment. After 6 months of rhGH therapy a significant improvement in left ventricular ejection fraction (from 53%±9% to 59%±9%,P <0.01), stroke volume index (from 41±11 to 47±13 ml/m²,P <0.05) and cardiac index (from 2.8±0.6 to 3.3±0.8 1/min/m²,P <0.01) was observed in GHD patients. In conclusion, prolonged lack of GH leads to impaired left ventricular function at rest. Reversal of this abnormality may be observed after 6 months of specific replacement therapy in patients with childhood-onset GHD.     

Assessment of left ventricular function: comparison between radionuclide angiography and semiquantitative two-dimensional echocardiographic analysis

Measurement of global left ventricular function is important in the follow-up of cardiac patients and is a good prognostic indicator in acute cardiac situations. We compared quantitative measurements of global left ventricular function made with radionuclide angiography (RNA) and contrast cardiac ventriculography (CVG) to visual semiquantitative estimates from two-dimensional echocardiographic images (2D-echo). Three hundred and thirty-nine consecutive patients who underwent RNA were assessed with 2D-echo within 3 months. In addition, 92 of these patients also underwent CVG (correlation of ejection fraction between CVG and RNA:r=0.82;P<0.0001). The RNA mean ejection fractions in the four 2D-echo groups (0=normal, 1=slightly, 2=moderate, or 3=severe reduced left ventricular function) differed markedly (P<0.0001); however, there was overlapping among the groups (2D-echo score/RNA ejection fraction: 0=57.3%±12.8%; 1=46.0%±12.9%; 2=29.6%±12.2%; and 3=24.6%±11.5%) and the difference between 2D-echo scores 2 and 3 was not significant. 2D-echo showed a good concordance in RNA classes (0=505; 1=35%–49%; 2=21%–34%; and 3=520% ejection fraction) 0 (133/166; 80%) and 3 (18/30; 60%) but low concordance in classes 1 (27/82; 33%) and 2 (21/61; 34%). For accurate assessment of global left ventricular ejection fraction, visual semiquantitative judgement of a 2D echocardiographic image is limited in comparison to CVG or RNA, especially in patients with a slight or moderate reduction in left ventricular ejection fraction.     

Left ventricular dimensions during isometric exercise in aortic valve incompetence assessed by M-mode echocardiography and gated equilibrium radionuclide angiography

We compared M-mode echocardiographic and gated equilibrium radionuclide angiography assessement of the left ventricular (LV) dimensions at rest and during isometric exercise in 18 patients with chronic aortic valve incompetence. The two methods showed a satisfactory correlation when comparing LV size at rest and during exercise (LV end-diastolic dimension in echocardiography vs LV end-diastolic volume in radionuclide angiography, r=0.80, P0.01 at rest and r=0.81, P0.01 during exercise; LV end-systolic dimension in echocardiography vs LV end-systolic volume in radionuclide angiography, r=0.81, P0.01 at rest and r=0.75; P0.01 during exercise), but fractional shortening in echocardiography and ejection fraction in radionuclide angiography did not correlate (r=0.27, not significant (NS) at rest and r=0.34, NS during exercise). Thus echocardiography and radionuclide angiography describe LV dimensions at rest and during handgrip exercise in a similar fashion, documenting the concordance of these noninvasive methods to describe LV size in aortic incompetence at rest and during exercise.     

Radionuclide monitoring of left ventricular function after sublingual nifedipine administration at rest and during moderate physical activity

BACKGROUND: This study investigates the acute effects of nifedipine administration on left ventricular (LV) function in patients with different degrees of heart failure at a fixed heart rate under resting conditions and during moderate physical activity. METHODS AND RESULTS: Eleven patients with non-rate-responsive DDD pacemakers were studied. According to baseline LV ejection fraction, patients were divided into 2 groups: 6 patients with an ejection fraction of less than 50% (group 1) and 5 patients with an ejection fraction of 50% or more (group 2). LV function was monitored by a radionuclide system (Vest) at rest and during moderate physical activity (10-minute walk test) before and after sublingual nifedipine administration (10 mg). In all patients, both the systolic blood pressure and diastolic blood pressure were significantly reduced (P <.05) 6 minutes after nifedipine administration. In group 1, end-diastolic volume and ejection fraction decreased after 3 minutes and remained significantly lower (P <.05) than resting values until 10 minutes after drug administration, whereas end-systolic volume was unchanged. In group 2, nifedipine induced a minor decrease in end-diastolic volume and a slight but not significant decrease in ejection fraction and end-systolic volume. During the walk test, nifedipine induced similar changes in all parameters of cardiac performance in both groups. CONCLUSIONS: In patients with impaired LV function, acute nifedipine administration has a negative effect on cardiac performance, which occurs before blood pressure reduction. On the other hand, during moderate physical activity, nifedipine does not affect the improvement in LV function.     

Evaluation of right ventricular volume and mass using retrospective ECG-gated cardiac multidetector computed tomography: comparison with first-pass radionuclide angiography

The purposes of this study were to evaluate the right ventricular (RV) volume and mass using cardiac multidetector computed tomography (MDCT) and to compare the cardiac MDCT results with those from first-pass radionuclide angiography (FPRA). Twenty patients were evaluated for the RV end-diastolic volume (RVEDV), the RV end-systolic volume (RVESV), the RV ejection fraction (RVEF), and RV mass using cardiac MDCT with a two-phase reconstruction method based on ECG. The end-diastolic phase was reconstructed at the starting point of the QRS complex on ECG, and the end-systolic phase was reconstructed at the halfway point of the ascending T-wave on ECG. The RV mass was measured for the end-systole. The RVEF was also obtained by FPRA. The mean RVEF (47±7%) measured by cardiac MDCT was well correlated with that (44±6%) measured by FPRA (r=0.854). A significant difference in the mean RVEF was found between cardiac MDCT and FPRA (p=0.001), with an overestimation of 2.9±5.3% by cardiac MDCT versus FPRA. The interobserver variability was 4.4% for the RVEDV, 6.8% for the RVESV, and 7.9% for the RV mass, respectively. Cardiac MDCT is relatively simple and allows the RV volume and mass to be assessed, and the RVEF obtained by cardiac MDCT correlates well with that measured by FPRA.     

Radionuclide determination of right and left ventricular stroke volumes

The relationship between radionuclide and thermodilution measurement of stroke volumes (SV) was investigated in 30 patients without valvular regurgitation or intracardiac shunt (group A) at rest and during exercise. Both attenuated radionuclide right ventricular (RV) and left ventricular (LV) SV measurements correlated well with the SV determined by the thermodilution method (r=0.87 and r=0.93, all P< 0.001). The reliability of the radionuclide method to estimate SV was evaluated prospectively in two additional groups of patients. In 11 patients without valvular regurgitation or intracardiac shunt (group B) the radionuclide RVSV and LVSV closely approximated to thermodilution SV at rest and during exercise. In 15 patients with aortic regurgitation (group C) the radionuclide stroke volume ratio correlated well with the angiographic regurgitant fraction. Thus, both RVSV and LVSV and the severity of aortic regurgitation can be reliably measured with gated radionuclide ventriculography.     

Diastolic or systolic left and right ventricular impairment at moderate doses of anthracycline?

A prospective study was carried out to assess the early and later alterations in left and right ventricular diastolic and systolic function after the termination of anthracycline therapy. In 33 women without cardiac disease who were treated by anthracycline therapy, cardiac function was evaluated by radionuclide angiography before the treatment (T₀) and 1 month (T₁) and 12 months (T₁₂) after the end of the treatment. Cardiac function was assessed by radionuclide measurement throughout treatment. Analysis of ejection fraction (EF), peak ejection rate (PER), time to PER (TPER), peak filling rate (PFR) and time to PFR (TPFR) was performed before and after treatment. To normalise radionuclide measurements of the ventricular diastolic function, the ratio of the PFR and the EF and the ratio of the PFR and the PER were calculated. No patient developed symptomatic congestive cardiac failure. One-way analysis of variance showed a significant decrease in the three parameters (EF, PER, PFR) over time only for the left ventricle (LV); no significant alterations appeared for the right ventricle (RV). The EF of the LV decreased from 59%±5% at T_o to 57%±6% at T₁ and 56%±5% at T₁₂. The PER of the LV fell from 3.03±0.40 end-diastolic volume per second (EDV/s) at T₀ to 2.79±0.47 at T₁ and 2.78±0.43 at T₁₂. The PFR of the LV dropped from 2.99±0.43 EDV/s at T₀ to 2.62±0.44 at T₁ and 2.56±0.42 at T₁₂. For the normalised ratios, no differences were observed. Significant differences were found for EF, PER and PFR between T₀ and T₁, and between T₀ and T₁₂, but no difference was found between T₁ and T₁₂. This report shows simultaneous impairment of the systolic and diastolic LV radionuclide parameters at 1 and 12 months after anthracycline therapy without alteration in the RV function.     

Radionuclide evaluation of left ventricular function with nonimaging probes

Portable nonimaging probes have been developed that can evaluate left ventricular function using radionuclide techniques. Two modes of data acquisition are possible with these probe systems, first-pass and gated. Precordial radiocardiograms obtained after a bolus injection can be used to determine cardiac output, pulmonary transit time, pulmonary blood volume, left ventricle ejection fraction, and left-to-right shunts. Gated techniques can be used to determine left ventricular ejection fraction and sytolic time intervals. Probe-determined indices of left ventricular function agree excellently with comparable measurements determined by conventional camera-computer methods as well as by invasive techniques. These have begun to be used in a preliminary manner in a variety of clinical problems associated with left ventricular dysfunction. This review discusses the types of probe systems available, the methods used in positioning them, and details the specifics of their data acquisition and processing capacity. The major criticisms of probe methods are that they are nonimaging and that they measure global rather than regional left ventricular function. In spite of these criticisms, probe systems, because of their portability, high sensitivity, and relatively low cost are useful supplements to conventional camera-computer systems for the measurement of parameters of left ventricular performance using radionuclide techniques.     

Reliability of first-pass radionuclide determination of cardiac output in the upright position at rest and during exercise

The reliability of non-invasive determination of cardiac output using first-pass radionuclide cardiography at rest and during exercise in the upright position was evaluated in 20 patients with coronary artery disease. Cardiac output values ranged from 2.97 to 5.99 1/min at rest and from 5.08 to 10.821/min during exercise. Cardiac output results obtained by the radionuclide method were compared with those derived from the thermodilution technique performed simultaneously. The mean difference between the two techniques was 0.02 1/min at rest and –0.341/min during exercise; the limits of agreement (mean±1.96 SD) were –1.29 to 1.33 1/min and –1.97 to 1.29 1/min, respectively, indicating an acceptable level of agreement. A high reproducibility of the radionuclide technique was found, with a mean difference between determinations by two observers of 0.03 1/min at rest and 0.21 1/min during exercise, the corresponding limits of agreement being –0.75 to 0.811/min and –0.79 to 1.21 1/min, respectively. With the aid of a variance component analysis of two determinations by each of four observers, 95% confidence intervals of ±10% at rest and ±12% during exercise were computed for the radionuclide cardiac output measurements. The observer variation was most pronounced for the part of the cardiac output determination related to measurement of left ventricular equilibrium activity during exercise. First-pass radionuclide cardiography is a reliable method for determination of cardiac output in cardiac patients at rest and during exercise in the upright position.     

A comparison of two radionuclide ejection-fraction techniques with contrast angiography in ischemic heart disease and valvular heart disease

First-pass radionuclide angiography (FPRA) in the 30° right anterior oblique and equilibrium gated radionuclide angiography (EGNA) in the 45° left anterior oblique were used for quantitative measurements of left ventricular ejection fraction (LVEF). Equipment used was a 400T gamma-camera interfaced with a Simis III Informatek computer. The results were compared with contrast angiography (CA). The aim of this study was to determine the sensitivity of both radionuclide techniques. The present data are based on 65 patients in whom CA and EGNA were performed. In 47 patients both FPRA and EGNA were performed. Results suggested that in ischemic heart disease (IHD) and valvular heart disease (VHD) the EGNA technique is well correlated with CA (r=0.9 and 0.73, respectively). FPRA correlated well only with CA in IHD (r=0.86), but not in VHD (r=0.18). This study indicates that both FPRA and EGNA are sensitive, noninvasive techniques for measuring ejection fraction in IHD, while in VHD, EGNA is more sensitive technique than FPRA.     

Assessment of left ventricular function by ECG-gated myocardial perfusion scintigraphy with image inversion technique: Comparison with equilibrium radionuclide angiography

BACKGROUND: Inversion of gated myocardial perfusion imaging has been proposed for the evaluation of left ventricular function. This study compared the results of inversion technique of gated left anterior oblique 45 degrees images (G-LAO 45 degrees) with those provided by equilibrium radionuclide angiography in the assessment of global left ventricular function in the same patients with suspected or known coronary artery disease. METHODS AND RESULTS: A total of 107 patients (85 men and 22 women, mean age 59 +/- 9 years) with suspected or documented coronary artery disease were studied. Eighty-seven underwent a 2-day stress/rest technetium-99m sestamibi single photon emission computed tomography with acquisition of G-LAO 45 degrees images on the day of rest, and 20 underwent thallium-201 stress/redistribution single photon emission computed tomography with G-LAO 45 degrees image acquisition immediately after redistribution imaging. An excellent correlation (P < .001) with no significant differences was found between left ventricular ejection fraction values provided by inversion G-LAO 45 degree and radionuclide angiography in 87 patients studied with Tc-99m sestamibi and 20 patients studied with TI-201. The Bland-Altman analysis demonstrated the difference in absolute ejection fraction values obtained by inversion G-LAO 45 degree images and radionuclide angiography as <8%. The inversion G-LAO 45 degrees left ventricular ejection fraction distinguishes the patients with myocardial infarction (ejection fraction = 43% +/- 13%) and without myocardial infarction (ejection fraction = 60% +/- 5%) (P < .001). In patients with left ventricular ejection fraction <40%, inversion G-LAO 45 degree images provide evaluation of left ventricular function comparable with that obtained by RNA. CONCLUSIONS: Semiautomated myocardial perfusion gated inversion technique analyzed with a count-based method is useful in the evaluation of left ventricular function and provides similar results to those of radionuclide angiography.     

The clinical utility of radionuclide ventriculography in cardiac transplantation

To assess ventricular function in patients who have undergone cardiac transplantation, 247 radionuclide ventriculograms were performed on 94 patients. During the first three days after transplantation, 19% demonstrated left ventricular dysfunction and 41% showed isolated right ventricular dysfunction. In 95 cases, radionuclide ventriculography was performed within 24 hr of myocardial biopsy. A reduction in left ventricular ejection fraction to less than 50% was significantly more common with moderate-severe rejection than with mild rejection. In six instances in which there was discordance between ventriculography and biopsy, radionuclide ventriculography proved particularly useful: three cases showed severe left ventricular dysfunction despite only mild rejection by biopsy, and three cases with ventricular dysfunction from rejection were missed by the initial biopsy. Thus, radionuclide ventriculography can provide functional data in transplant patients that is complementary to myocardial biopsies since biopsy grade is a poor predictor of left ventricular function and biopsy can miss significant rejection.