Beat-to-beat left ventricular performance in atrial fibrillation: radionuclide assessment with the computerized nuclear probe

There is wide beat-to-beat variability in cycle length and left ventricular performance in patients with atrial fibrillation. In this study, left ventricular ejection fraction and relative left ventricular volumes were evaluated on a beat-to-beat basis with the computerized nuclear probe, an instrument with sufficiently high sensitivity to allow continuous evaluation of the radionuclide time-activity curve. Of 18 patients with atrial fibrillation, 5 had mitral stenosis, 6 had mitral regurgitation, and 7 had coronary artery disease. Fifty consecutive beats were analyzed in each patient. The mean left ventricular ejection fraction ranged from 17 to 51%. There was substantial beat-to-beat variation in cycle length and left ventricular ejection fraction in all patients, including those with marked left ventricular dysfunction. In 14 patients who also underwent multiple gated cardiac blood pool imaging, there was an excellent correlation between mean ejection fraction derived from the nuclear probe and gated ejection fraction obtained by gamma camera imaging (r = 0.90). Based on beat-to-beat analysis, left ventricular function was dependent on relative end-diastolic volume and multiple preceding cycle lengths, but not preceding end-systolic volumes. This study demonstrates that a single value for left ventricular ejection fraction does not adequately characterize left ventricular function in patients with atrial fibrillation. Furthermore, both the mean beat-to-beat and the gated ejection fraction may underestimate left ventricular performance at rest in such patients.     

Good correlation between gated single photon emission computed myocardial tomography and contrast ventriculography in the assessment of global and regional left ventricular function

Purpose: The purpose of this study was to determine the reliability of the measured left ventricular ejection fraction (LVEF) and wall motion analysis by the recently introduced quantitative electrocardiographically (ECG)-gated myocardial perfusion single-photon emission computed myocardial tomography technique (gated SPECT) (QGS). Materials and methods: We compared technetium-99 m tetrofosmin gated SPECT imaging and contrast ventriculography in the assessment of global and regional left ventricular function in 74 patients with undiagnosed chest pain of whom 27 sustained a previous myocardial infarction. Results: Linear regression analysis demonstrated that gated SPECT determined LVEF correlated well with LVEF determined from contrast ventriculography (y = 0.95x + 1.9, r ² = 0.84, p < 0.0001). Bland–Altman plot analysis showed no systematic difference between the two sets of values derived from the two imaging approaches over a wide range of LVEF values. Exact agreement of segmental wall motion scores was 460 of 518 (89%) segments with a kappa value of 0.76 (p < 0.0001). Conclusion: We conclude that gated SPECT imaging is an accurate and reliable clinical tool to accurately measure global and regional left ventricular function.     

Serial measurements of left ventricular ejection fraction by radionuclide angiography early and late after myocardial infarction

The left ventricular ejection fraction was determined serially with radioisotope angiography in 63 patients with acute myocardial infarction. After the peripheral injection of a bolus of technetium-99m, precordial radioactivity was recorded with a gamma scintillation camera and the ejection fraction calculated from the high frequency left ventricular time-activity curve. Since this technique requires no assumptions with respect to left ventricular geometry, it is particularly useful in patients with segmental left ventricular dysfunction. Serial measurements during the first 5 days after hospital admission were made in 50 patients, 30 of whom were studied during the subsequent 2 to 39 months (mean 19.9 months). Late follow-up serial studies were also performed in an additional 13 patients who had only one measurement of the left ventricular ejection fraction during the early postinfarction period.Early after infarction, the left ventricular ejection fraction was normal (more than 0.52) in only 15 of the 63 patients, and averaged 0.52 ± 0.05 (standard deviation) in the 27 patients with an uncomplicated infarct. The ejection fraction was reduced in 24 patients with mild to moderate left ventricular failure (0.40 ± 0.05, P < 0.0001) and in the 12 patients with overt pulmonary edema (0.33 ± 0.07, P < 0.0001). In 35 patients the ejection fraction correlated with the mean pulmonary arterial wedge pressure (r = 0.72). In 15 patients with normal left ventricular wall motion by heart motion videotracking, the ejection fraction was significantly higher (0.53 ± 0.08) than in the 26 patients with regional left ventricular dysfunction (0.41 ± 0.10, P < 0.0001). During the early postinfarction period, the left ventricular ejection fraction improved in 55 percent of patients and remained unchanged or decreased in 45 percent. A further increase in the ejection fraction was noted in 61 percent of patients during the late follow-up period. Patients with an initially low or decreasing ejection fraction had a significantly greater incidence of early mortality and left ventricular dysfunction (P < 0.02) than those whose ejection fraction was normal or improved to normal early after infarction. These data indicate that the ejection fraction is a sensitive indicator of left ventricular function after acute myocardial infarction and that serial measurements are helpful in predicting early mortality and morbidity.     

Posterior wall velocity: an unreliable index of total left ventricular performance in patients with coronary artery disease

Posterior wall velocity determined by use of echocardiography has been proposed as an index of total left ventricular performance in patients with ischemic heart disease. Accordingly, in 9 normal subjects and 39 patients with angiographically documented coronary artery disease, we compared mean endocardial posterior wall velocity determined by echocardiography with echocardiographic and biplane cineangiographic calculations of ejection fraction and the mean rate of circumferential fiber shortening (mean V_CF), and with externally recorded systolic time intervals. All studies were performed on the same day in each patient. Mean endocardial posterior wall velocity averaged 4.6 cm/sec (range 2.9 to 8.7) and correlated poorly with echocardiographic ejection fraction (r = 0.47), cineanglographic ejection fraction (r = 0.26), cineangiographic mean V_CF (r = 0.47), the ratio of preejection period to left ventricular ejection time (r = ?0.35) and the preejection period corrected for heart rate (r = ?0.30). Substitution of maximal for mean endocardial posterior wall velocity did not improve the separation of normal from depressed left ventricular performance. Epicardial posterior wall velocity, a measurement more easily obtainable than endocardial posterior wall velocity, also did not correlate well with systolic time intervals or with ejection fraction or mean v_cf derived from the echocardiogram and cineangiogram. Both endocardial and epicardial posterior wall velocity values were poorly reproducible on a day to day or a beat to beat basis. We conclude that neither endocardial nor epicardial posterior wall velocity, whether derived as a mean or a maximum, provides an accurate measure of total left ventricular performance in patients with coronary artery disease.     

Value of the QRS complex in assessing left ventricular ejection fraction

The relation between electrocardiographic findings and the angiographic left ventricular ejection fraction and the augmented ejection fraction after a premature ventricular contraction was investigated in 73 patients with documented chronic coronary artery disease. The patients were separated into four groups according to the presence or absence of abnormal Q waves. Twenty-four patients had diaphragmatic myocardial infarction, 21 had anterior myocardial infarction, 15 had both and 13 had no myocardial infarction. There were no statistically significant differences in cardiac index, left ventricular end-diastolic pressure or number of coronary vessels showing critical narrowing in the four groups. The sum of R waves (in mv) in leads aVL, aVF and V₁ to V₆ (ΣR) was correlated with the ejection fraction (EF) and the augmented ejection fraction (EFa). EF in percent = 6.6 ΣR mv + 9.4 (no. = 73, r = 0.61); and EFa in percent = 8.6 ΣR mv + 11.0 (no. = 73, r = 0.77). Among patients with ΣR of less than 4.0 mv, augmented ejection fraction was less than 0.45 in 73 percent; among patients with ΣR of 4.0 mv or more the augmented ejection fraction was greater than 0.45 in 93 percent (P < 0.001). Thus, the ΣR, calculated from six precordial and two augmented leads in patients with chronic coronary artery disease, correlated with both ejection fraction and augmented ejection fraction. The electrocardiogram in patients with coronary artery disease may prove useful as a simple, readily available and noninvasive guide in the assessment of left ventricular function in patients with coronary artery disease.     

A scintiphotographic method for measuring left ventricular ejection fraction in man without cardiac catheterization

A radioactive tracer method for the measurement of left ventricular ejection fraction in man without cardiac catheterization is described. The tracer (^99mtechnetium-labeled albumin) is injected intravenously. Images of the heart at end-systole and end-diastole are obtained using a scintillation camera and an electronic gate triggered by the patient's electrocardiogram. Each image is composed of 300,000 counts, representing a summation of 200 to 400 heartbeats at end-systole and end-diastole. An outline of the left ventricular free wall is drawn from each gated image. The position of the aortic and mitral valve planes is determined using a radionuclide angiogram obtained at the time of tracer injection. Left ventricular ejection fraction is calculated from the area and length of the long axis of the ventricular outline at end-systole and end-diastole. Determinations of ejection fraction in 20 patients using this tracer method were correlated with measurements obtained by contrast cineangiography with the following results: ejection fraction r = +0.92, P < 0.001; end-diastolic volume r = −0.76, P < 0.001; and end-systolic volume r = −0.75, P < 0.001.     

Computerized orthogonal electrocardiogram: relation of QRS forces to left ventricular ejection fraction

Several studies have suggested a relation between Q wave or R wave amplitude in the standard 12 lead electrocardiogram and the left ventricular ejection fraction. Accordingly, we analyzed the relation between Q wave and R wave amplitudes obtained with computerized orthogonal (Frank) electrocardiography and the angiographically determined left ventricular ejection fraction. A computerized orthogonal electrocardiogram was obtained before cardiac catheterization in 52 consecutive patients being evaluated for chest pain. The electrocardiographic diagnosis indicated 14 normal tracings, 20 inferior, 12 anterior and 6 lateral myocardial infarctions. Linear correlations were made between X, Y and Z axis lead voltages and ejection fraction. A significant correlation was obtained between the voltages of the R waves in the X, Y and Z leads (Rx, Ry, Rz) and of the Q waves in lead Z (Qz) as well as total amplitude Qx + Rx, Qy + Ry and ejection fraction (P <0.01). Arithmetic summation of Rx + Ry + Qz (∑R) significantly augmented the correlation with ejection fraction (r = 0.78, P <0.001); this was only slightly improved by multivariate analysis of Rx, Ry, Qz (r = 0.80, P <0.001) or Rx, Ry, Rz, Qx, Qy, Qz (r = 0.82, P <0.001). ∑R, utilized as a means of predicting whether an ejection fraction was more or less than 50 percent, had an accuracy rate of 92 percent. Thus, ∑R contains important information that can be used practically in the precatheterization evaluation of patients with chest pain and follow-up evaluation of patients with myocardial infarction.     

Evaluation of left ventricular ejection fraction in coronary disease patients by the gated blood pool method and cineangiography. Critical analysis of divergences between the 2 methods

In order to assess the reliability of left ventricular ejection fraction as estimated by gated blood pool method, radionuclide angiography (LAO) and single plane (RAO) contrast cineangiocardiography were performed within 14 days in 60 patients with coronary artery disease. The mean value of radionuclide ejection fraction was found to be 55 +/- 16%; contrast cineangiographic ejection fraction was 57 +/- 15%; r = 0.92. In 23 patients with previous anterior myocardial infarction gated blood pool method was found to underestimate left ventricular ejection fraction when compared with contrast cineangiography. The observed underestimation was wide significant in 11 patients with previous anterior infarction, low (less than 50%) radioisotopic ejection fraction and septal akinesia and/or apical dyskinesia; radionuclide ejection fraction = 33 +/- 8%; contrast cineangiographic ejection fraction = 42 +/- 9%; r = 0,76. This study confirms that the values of left ventricular ejection fraction as estimated by gated blood pool method in coronary patients are quite reliable; moreover, the intrinsic variability of the data is low. This may be not true in patients with previous anterior myocardial infarction. The Authors discuss the possible causes of disagreement between radioisotopic and contrastographic ejection fraction in patients with previous anterior infarction and poor left ventricular function: physical problems of measuring ejection fraction by gated blood pool in dilated ventricles; possible mistakes in evaluating blood pool due to the low mobility of the blood mass nearest to the scintillation camera; inhability of contrast cineangiography in RAO to recognize the interventricular septum and evaluate its kinetic abnormalities; unreliability of the geometrical model of revolution elypsoid in calculating end-systolic volumes in ventricles with abnormal wall-kinesis.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effects of digoxin on left ventricular function in coronary artery disease patients

To assess whether digitalis modifies or prevents the deterioration of the left ventricular ejection fraction and wall motion during acute ischemia, we performed gated blood pool radionuclide ventriculograms in 15 patients with angiographically documented coronary artery disease. All patients were studied in the resting state and during maximal supine bicycle exercise, both before and 1 hour after 1 mg intravenous digoxin.There was no significant difference, pre-digoxin vs post-digoxin, in exercise tolerance (415 ± 84 vs 418 ± 107 seconds), number of segments with abnormal resting wall motion (12 vs 11) or exercise wall motion (21 vs 19). Ten patients developed angina during the same exercise load, irrespective of digoxin administration. Twelve patients had subnormal left ventricular ejection fraction during exercise pre-digoxin, vs 13 patients post-digoxin (P = ns). In the resting state, the left ventricular ejection fraction was higher after digoxin (53 ± 14% pre vs 58 ± 14% post, P < 0.05). During exercise, however, the left ventricular ejection fraction was not significantly improved after digoxin (50 ± 16% pre vs 53 ± 17% post, P = ns).These data indicate that although acute administration of digoxin improves the resting left ventricular function, it does not improve exercise tolerance to angina. Furthermore, intravenous digoxin does not appear to prevent the deterioration of left ventricular wall motion and ejection fraction during exercise induced ischemia.     

Noninvasive detection of left ventricular dysfunction with a portable electrocardiographic gated scintillation probe device

A comparison of left ventricular function data derived from a low cost, portable electrocardiographic gated scintillation probe (nuclear stethoscope) with conventional scintiangiographic data was performed in 68 patients. Ejection fraction correlation (r = 0.86, p < 0.005) was better in patients with uniform wall motion than in those with regional asynergy (r = 0.68 p < 0.01). Probe variables reflecting systolic emptying rates, diastolic filling rates and timing intervals, and relative volumes analyzed in combination provided 100 percent sensitivity, specificity, and predictive value in detecting abnormal left ventricular performance. The results suggest that radionuclide angiography with an electrocardiographic gated scintillation probe is a sensitive, rapid and relatively inexpensive portable method of screening for cardiac dysfunction with a yield similar to that from the more costly gamma camera derived scintiangiogram.     

Determination of left ventricular ejection fraction by visual estimation during real-time two-dimensional echocardiography

It has been shown that the measured reduction in the cross-sectional area of the left ventricle (LV), as viewed in the short axis, closely approximates its ejection fraction (EF). We assessed the reliability of using two-dimensional echocardiography (2DE) to visually estimate the EF during real-time viewing, without the need of digitizers, planimetry, or calculations. Twenty-five adult hospitalized patients with either suspected or known cardiac disease were evaluated prospectively. Each patient also had gated nuclear angiography during the same admission, and 14 had cardiac catheterization with left ventriculography. The EF was determined by 2DE using a visual estimate of the percent area reduction of the LV cavity in the short-axis view at the level of the papillary muscles. All 2 DE studies were read by two or more blinded reviewers, with a value for the EF to the nearest 2.5% determined by consensus. These values correlated closely to the values determined in all 25 patients with gated nuclear angiography (r = 0.927) and the 14 patients who had left ventriculography (r = 0.935). We believe that this method of visually estimating the LVEF will enable echocardiographers to easily use 2 DE for a reliable and instantaneous assessment of ventricular function, without the need of sophisticated analytical equipment.     

Validation of left ventricular function parameters acquired with the non-imaging nuclear probe: comparison with tantalum marker cine-fluoroscopy

We evaluated the accuracy of the non-imaging nuclear probe for measuring various parameters of left ventricular function by comparing these with simultaneous measurements acquired via tantalum marker cine-fluoroscopy. Eight patients with surgically implanted mid-myocardial tantalum markers were studied during cardiac catheterization. High temporal resolution tantalum marker-derived volume/time curves were generated and calibrated to absolute endocardial volumes by comparison with contrast left ventricular angiography. Left ventricular function parameters were acquired at baseline and during atrial pacing, nitroprusside infusion and volume loading. Simultaneous measurements obtained with the nuclear probe and via tantalum marker cine-fluoroscopy were compared. The following correlation coefficients were obtained: ejection fraction, r = 0.49, P less than 0.001; peak ejection rate, r = 0.41, P less than 0.01; mean ejection rate, r = 0.62, P less than 0.001; time to peak ejection, r = 0.73, P less than 0.001; peak filling rate, r = 0.73, P less than 0.001; time to peak filling, r = 0.58, P less than 0.001. Relative changes in end-diastolic volume were accurately tracked by the nuclear probe in six of seven patients (r values 0.77-0.93). These results suggest that measurements of certain left ventricular volume parameters with the nuclear probe may not accurately reflect true volume changes as measured by tantalum marker cine-fluoroscopy. Although, the probe may be useful in tracking relative changes in end-diastolic volume, we would advise caution in using this instrument for studies requiring accurate measurements of ejection and filling parameters.     

Non-invasive determination of left ventricular ejection fraction using a mobile ECG-triggered scintillation measuring probe. Comparison of cineventriculography, echocardiography and radionuclide ventriculography

In 29 unselected patients, the left ventricular ejection fraction was evaluated using a mobile ECG-gated scintillation probe (Nuclear Stethoscope) after in vivo labeling of the erythrocytes with 15 mCi technetium-99m. To validate the method, the Nuclear Stethoscope measurements were correlated to the results of: 1. Single-plane contrast cineventriculography in the right and left anterior oblique projections (RAO, LAO), 2. Radionuclide ventriculography with a gamma camera computer system, 3. Two-dimensional echocardiography from the apical two- and four-chamber views. The ejection fraction measured by the Nuclear Stethoscope showed a close correlation to the values obtained by cineventriculography in the RAO projection (r = 0.748) and radionuclide ventriculography (r = 0.785). In this group of unselected patients, the correlations with the results of two-dimensional echocardiography were poor (r = 0.451 and 0.557). Cineventriculographic findings and radionuclide ventriculography correlated well (RAO: r = 0.786; LAO: r = 0.758). The Nuclear Stethoscope provides a simple, reliable, and noninvasive method for measuring ventricular ejection fraction. Ongoing studies indicate that the Nuclear Stethoscope is a valid method even at a lower dose of 5 mCi technetium-99m.     

The influence of age and gender on left ventricular response to supine exercise in asymptomatic normal subjects

The performance of normal subjects during radionuclide ventriculography has been related to age, but the combined effects of age and sex on exercise ventricular function are not well described. We studied 55 normal volunteers, 27 men (age = 30 ± 10 years) and 28 women (age = 33 ± 14 years), free of chest pain syndromes, during supine rest/exercise radionuclide ventriculography performed to fatigue. Resting left ventricular ejection fraction did not differ between male and female subjects (64 ± 5.4 vs 64 ± 6.1; p = NS). Both the peak left ventricular ejection fraction (78 ± 4.4 vs 72 ± 9.2; p < 0.001) and the change in ejection fraction with exercise (14 ± 4.0 vs 7.9 ± 7.0; p < 0.001) were significantly greater in men compared to respective values in women. Regression analysis showed that sex (r = 0.51; p < 0.001) but not age (r = −0.18; p = 0.19) was a significant predictor of change in ejection fraction with exercise. Data on left ventricular volume response to exercise, available in 43 subjects, revealed that men had a greater percentage of decline in end-systolic volume with exercise than women (−47 ± 15 vs −24 ± 26; p < 0.001). It is concluded that sex exerts a significant influence on normal left ventricular response to fatigue-limited supine exercise and that the gender difference is mediated, in part, by left ventricular end-systolic volume response to exercise.     

Radionuclide analysis of pulmonary blood volume: The response to spontaneous angina pectoris and sublingual nitroglycerin in patients with coronary artery disease

By manually assigning pulmonary regions of interest and deriving pulmonary time-activity (volume) curves, we were able to make count estimates of pulmonary blood volume (PBV) from gated cardiac blood pool scans. Five patients with coronary heart disease developed angina spontaneously while under a gamma camera. This produced an increase in cardiac volumes (p < 0.05), a reduction in left ventricular ejection fraction (p < 0.01), along with a marked increase in PBV (0.010 ± 0.002 to 0.015 ± 0.003 untils, p < 0.05). Nitroglycerin was then administered and reduced PBV in association with a return to normal in cardiac systolic function and size. In patients with stable chronic ischemic heart disease, sublingual nitroglycerin also reduced PBV (p < 0.05), although not as much as when administered during an anginal episode. We conclude that gated imaging of the chest can be utilized to follow changes in PBV serially. These changes can be utilized to evaluate clinically important changes in hemodynamic status and the response to pharmacologic interventions.     

Myocardial structure and function in patients with aortic valve disease and their relation to postoperative results

Left ventricular angiographic studies were performed before and 6 months after aortic valve replacement with a Björk-Shiley prosthesis in 21 patients, 5 with aortic stenosis, 8 with mixed aortic valve lesions and 8 with aortic insufficiency. The degree of myocardial fibrosis and myocardial ultrastructural changes were evaluated from transmural needle biopsy specimens obtained from the left ventricular anterior free wall at operation. Twelve patients without heart disease served as control subjects for angiographic data. Patients with aortic valve disease had a significantly higher left ventricular mass before operation than control subjects and a lower ejection fraction and mean normalized systolic ejection rate. After operation left ventricular mass decreased considerably but did not reach normal level. Ejection fraction and mean normalized systolic ejection rate became normal in all patients with aortic valve disease. The percent fibrosis determined with morphometry was significantly higher in the subendocardium than in the subepicardium of pressure-overloaded hearts (predominant stenosis) (19 versus 13 percent) but equal in both layers of volume-overloaded hearts (predominant regurgitation) (19 versus 18 percent). Electron microscopy revealed significant intracell alterations of the nucleus, sarcomeres, mitochondria and cytoplasmic reticulum. When all patients, regardless of type of aortic valve lesion, were considered, there was no significant correlation before operation between percent fibrosis and ejection fraction (r 0.10) or mean normalized systolic ejection rate (r 0.02) but a significant inverse relation between left ventricular mass and ejection fraction (r 0.54) as well as mean normalized systolic ejection rate (r 0.49).These data suggest that (1) Depressed left ventricular function in aortic valve disease is associated with ultrastructural degenerative cell changes, but complete recovery of cardiac function after aortic valve replacement is not prevented by these changes. (2) Interstitial myocardial fibrosis is not a primary determinant of depressed cardiac function in aortic valve disease.     

Nongeometric determination of right ventricular volumes from equilibrium blood pool scans

It has previously been shown that left ventricular volumes can be measured accurately from radionuclide gated blood pool scintigrams by quantttating the background-corrected and volume-normalized ventricular activity at end-diastole and end-systole. To determine if this same technique can be applied to the calculation of right ventricular volumes, simultaneous measurements of right ventricular stroke volume were performed using gated scintigraphy and the thermodilution technique in 60 patients without clinical or hemodynamic evidence of right-sided regurgitation. Three techniques for the acquisition of the radionuclide studies were evaluated. The best correlation between scintigraphic and thermodilution determinations of stroke volume was obtained for studies acquired with a 25 ° rotating slant hole collimator positioned in a 10 to 15 ° left anterior oblique projection with the collimator slant directed toward the cardiac apex along the axis of the interventricular septum: Thermodilution stroke volume = 4.2 (scintigraphic stroke volume) + 10.3 ml (correlation coefficient [r] = 0.88; standard error of the estimate = 9.3 ml; probability [p] < 0.0001). This scintigraphic acquisition technique was superior to (1) a straight bore collimator positioned in a septal projection (30 to 50 ° left anterior oblique with 15 ° caudal tilt), and (2) a 25 ° slant hole collimator positioned in a similar septal projection with the collimator slant directed caudally. This method was evaluated prospectively in an additional 14 patients, and there was excellent agreement between stroke volumes obtained with thermodilution and scintigraphic methods (r = 0.96, p < 0.001). In addition, measurements of right ventricular ejection fraction by the equilibrium method agreed closely with those obtained with a gated first pass technique (r = 0.94, p < 0.001, n = 14). With use of the scintigraphic right ventricular ejection fraction and the relation between scintigraphic and thermodilution measurements of right ventricular stroke volume, right ventricular end-diastolic and end-systolic volumes can be estimated. Thus, nongeometric radionuclide techniques may be used for the quantitation of right ventricular volumes.     

Quantitative radionuclide angiocardiography: Detection and quantitation of left to right shunts

In 105 patients detection and quantitation of left to right shunts was performed using quantitative radionuclide angiocardiography. The radionuclide angiocardiograms were acquired and analyzed by a gamma camera interfaced to a digital computer system. Pulmonary to systemic flow ($\text{Qp}\text{Qs}$) ratios were calculated by analysis of pulmonary time-activity histograms using a gamma variate model. All patients were studied with cardiac catheterization, left ventricular angiocardiography and radionuclide angiocardiography. The radionuclide method allowed precise detection and quantitation of left to right shunts with a $\text{Qp}\text{Qs}$ ratio of 1.2 to 3.0. There was good agreement between the $\text{Qp}\text{Qs}$ ratio calculated by oximetry at cardiac catheterization and radionuclide angiocardiography (r = 0.94). The information gathered with this nontraumatic method appears sufficiently reliable to be used in the management of patients.     

Echocardiographic evaluation of right ventricular function in complete transposition of the great arteries: angiographic correlates.

Right ventricular function of patients with complete transposition of the great arteries may be impaired. To assess whether the M mode echocardiogram could predict right ventricular function 64 echocardiograms and ventricular angiograms of 62 patients were studied, 33 obtained before repair of the defect (group I) and 31 (including 2 from patients in group I) obtained after the Mustard procedure (group II). Each group was subdivided according to whether a ventricular septal defect or patent ductus arterposus was or had been present preoperatively.The right ventricular preejection period was expressed as the ratio of the observed to the predicted value for a systemic left ventricle. This value was above normal In all groups and was not significantly different in the 13 patients with right bundle branch block. The observed ejection time expressed as a percent of that predicted for a systemic left ventricle correlated with right ventricular ejection fraction (r = 0.47). The ratio of the observed preejection period/ejection time had a higher correlation with right ventricular ejection fraction (r = ? 0.70). Nine patients had a low right ventricular ejection fraction (an ejection fraction of 0.55 or less was considered indicative of poor right ventricular function). These nine patients were all in group II and all had right bundle branch block.Most patients with poor right ventricular function had had a ventricular septal defect or patent ductus arteriosus before repair of the transposition, and postoperatively had angiographic tricuspld regurgitation, right bundle branch block, a preejection period/ejection time ratio greater than 0.55 and a percent predicted ejection time of 96 percent or less. Most patients who had good right ventricular function (ejection fraction greater than 0.55) had none of these findings. Systolic time intervals obtained with M mode echocardiography can be used for the assessment and longitudinal follow-up of right ventricular function in patients with transposition.     

AI Based CMR Assessment of Biventricular Function: Clinical Significance of Intervendor Variability and Measurement Errors

ObjectivesThe aim of this study was to determine whether left ventricular ejection fraction (LVEF) and right ventricular ejection fraction (RVEF) and left ventricular mass (LVM) measurements made using 3 fully automated deep learning (DL) algorithms are accurate and interchangeable and can be used to classify ventricular function and risk-stratify patients as accurately as an expert.BackgroundArtificial intelligence is increasingly used to assess cardiac function and LVM from cardiac magnetic resonance images.MethodsTwo hundred patients were identified from a registry of individuals who underwent vasodilator stress cardiac magnetic resonance. LVEF, LVM, and RVEF were determined using 3 fully automated commercial DL algorithms and by a clinical expert (CLIN) using conventional methodology. Additionally, LVEF values were classified according to clinically important ranges: <35%, 35% to 50%, and ≥50%. Both ejection fraction values and classifications made by the DL ejection fraction approaches were compared against CLIN ejection fraction reference. Receiver-operating characteristic curve analysis was performed to evaluate the ability of CLIN and each of the DL classifications to predict major adverse cardiovascular events.ResultsExcellent correlations were seen for each DL-LVEF compared with CLIN-LVEF (r = 0.83-0.93). Good correlations were present between DL-LVM and CLIN-LVM (r = 0.75-0.85). Modest correlations were observed between DL-RVEF and CLIN-RVEF (r = 0.59-0.68). A >10% error between CLIN and DL ejection fraction was present in 5% to 18% of cases for the left ventricle and 23% to 43% for the right ventricle. LVEF classification agreed with CLIN-LVEF classification in 86%, 80%, and 85% cases for the 3 DL-LVEF approaches. There were no differences among the 4 approaches in associations with major adverse cardiovascular events for LVEF, LVM, and RVEF.ConclusionsThis study revealed good agreement between automated and expert-derived LVEF and similarly strong associations with outcomes, compared with an expert. However, the ability of these automated measurements to accurately classify left ventricular function for treatment decision remains limited. DL-LVM showed good agreement with CLIN-LVM. DL-RVEF approaches need further refinements.