Comparison of symptom-limited and low level exercise tolerance tests early after myocardial infarction.

OBJECTIVES: This study was conducted to determine the diagnostic yield and risks of a symptom-limited treadmill exercise test before hospital discharge. BACKGROUND: Currently, predischarge low level and 6-week symptom-limited exercise treadmill tests are recommended for risk stratification after myocardial infarction. However, few data exist on the safety and value of a predischarge symptom-limited exercise test. METHODS: We utilized a modified Bruce protocol starting at 1.7 mph and 0 grade with 3-min stages in 150 consecutive patients 6.4 +/- 3.1 days after myocardial infarction. Each exercise test was interpreted for duration, symptoms and ST segment changes at the low level (70% of predicted heart rate) and symptom-limited end point. RESULTS: There were no complications related to the symptom-limited exercise tests. The test results were positive in only 23% of the patients at the low level end point, but were positive in 40% of the patients at the later symptom-limited end point (p < 0.001). During a mean follow-up period of 15 +/- 5 months in 138 patients (92%), 50 patients (36%) had a cardiac event. Of the patients with a cardiac event, significantly more (p < 0.001) had a positive exercise test at the symptom-limited end point (31 vs. 16 patients). Five patients with a negative and 14 patients with a nondiagnostic symptom-limited exercise test had an event. CONCLUSIONS: In patients with uncomplicated myocardial infarction, we demonstrated the safety of an early symptom-limited treadmill exercise test. Symptom-limited exercise tests will identify more patients with inducible ischemia who are at risk of future cardiac events and who may benefit from early intervention.

Freehand three-dimensional echocardiography for measurement of left ventricular mass: in vivo anatomic validation using explanted human hearts.

OBJECTIVES: We sought to validate freehand three-dimensional echocardiography for measuring left ventricular mass and to compare its accuracy and variability with those of conventional echocardiographic methods. BACKGROUND: Accurate measurement of left ventricular mass is clinically important as a predictor of morbidity and mortality. Freehand three-dimensional echocardiography eliminates geometric assumptions used by conventional methods, minimizes image positioning errors using a line of intersection display and increases sampling of the ventricle. Preliminary studies have shown it to have high accuracy and low variability. METHODS: Twenty-eight patients awaiting heart transplantation were examined by conventional and freehand three-dimensional echocardiography. Left ventricular mass was determined by the M-mode ("Penn-cube") method, the two-dimensional truncated ellipsoid method and three-dimensional surface reconstruction. The ventricles of 20 explanted hearts were obtained, trimmed and weighed. Echocardiographic mass by each method was compared with true mass by linear regression. Accuracy, bias and interobserver variability were calculated. RESULTS: For three-dimensional echocardiography, the correlation coefficient, standard error of the estimate, root mean square percent error (accuracy), bias and interobserver variability were 0.992, 11.9 g, 4.8%, -4.9 g and 11.5%, respectively. For the two-dimensional truncated ellipsoid method they were 0.905, 38.5 g, 15.6%, 15.4 g and 23.3%. For the M-mode ("Penn-cube") method they were 0.721, 96.9 g, 53.0%, 109.2 g and 19.5%. CONCLUSIONS: Freehand three-dimensional echocardiography for measurement of left ventricular mass has high accuracy and low variability and is superior to conventional methods in hearts of abnormal size and geometry.

Identification of false positive exercise tests with use of electrocardiographic criteria: a possible role for atrial repolarization waves.

Atrial repolarization waves are opposite in direction to P waves, may have a magnitude of 100 to 200 mu V and may extend into the ST segment and T wave. It was postulated that exaggerated atrial repolarization waves during exercise could produce ST segment depression mimicking myocardial ischemia. The P waves, PR segments and ST segments were studied in leads II, III, aVF and V4 to V6 in 69 patients whose exercise electrocardiogram (ECG) suggested ischemia (100 mu V horizontal or 150 mu V upsloping ST depression 80 ms after the J point). All had a normal ECG at rest. The exercise test in 25 patients (52% male, mean age 53 years) was deemed false positive because of normal coronary arteriograms and left ventricular function (5 patients) or normal stress single photon emission computed tomographic thallium or gated blood pool scans (16 patients), or both (4 patients). Forty-four patients with a similar age and gender distribution, anginal chest pain and at least one coronary stenosis greater than or equal to 80% served as a true positive control group. The false positive group was characterized by 1) markedly downsloping PR segments at peak exercise, 2) longer exercise time and more rapid peak exercise heart rate than those of the true positive group, and 3) absence of exercise-induced chest pain. The false positive group also displayed significantly greater absolute P wave amplitudes at peak exercise and greater augmentation of P wave amplitude by exercise in all six ECG leads than were observed in the true positive group.(ABSTRACT TRUNCATED AT 250 WORDS)

Validation of three-dimensional echocardiography for quantifying the extent of dyssynergy in canine acute myocardial infarction: comparison with two-dimensional echocardiography.

OBJECTIVES: This study was designed to compare the accuracy of three- and two-dimensional echocardiography for quantifying the extent of abnormal wall motion in experimental acute myocardial infarction, as correlated with the pathologic determination of infarct size. BACKGROUND: Two-dimensional echocardiographic estimations of the fraction of myocardium showing abnormal wall motion are often used as an index of infarct size even though they rely on image plane positioning and geometric assumptions that may not be valid. Three-dimensional echocardiographic reconstruction of the endocardial surface eliminates the need for these assumptions and may improve echocardiographic estimates of infarct size. METHODS: Coronary ligation was performed in 14 open chest dogs, and echocardiographic imaging of the ventricle was performed 6 h later. Three-dimensional echocardiography used seven or eight spatially registered short-axis images to measure percent of endocardial surface and mass showing abnormal wall motion. Three two-dimensional echocardiographic methods using multiple, nonpatially registered images were evaluated. One method used seven or eight-axis slices and a summation of discs algorithm for computing surface area. The second method used the same images and a conical model for the left ventricle. The third used basal, middle and apical short-axis plus apical four- and two-chamber views comparing summed endocardial lengths showing abnormal wall motion with the total of the endocardial dimensions, expressed as percent. The percent of left ventricular mass and surface area infarcted was determined by staining with triphenyltetrazolium chloride. RESULTS: Three-dimensional echocardiographic measurements of endocardial surface and correlated more closely with infarct mass (r = 0.94, SEE +/- 3.6%) than did the two-dimensional method using the summation of discs algorithm (r = 0.85, SEE +/- 6.6%), he summation of conical sections algorithm (r = 0.82, SEE +/- 5.4%) or the method using summed endocardial lengths (r = 0.79, SEE +/- 7.4%). Limits of agreement analysis comparing mass showing abnormal wall motion with anatomic infarct mass surface area showing abnormal wall motion with anatomic infarct surface area showed the smallest limits for three-dimensional echocardiography. CONCLUSIONS: Three-dimensional echocardiography is a more accurate means of noninvasively estimating myocardial infarct size in this canine model than two-dimensional echocardiography.

Three-dimensional echocardiographic measurement of left ventricular volume in vitro: comparison with two-dimensional echocardiography and cineventriculography.

OBJECTIVES: This study was designed to compare three-dimensional echocardiography, two-dimensional echocardiography and cineventriculography for the purpose of measuring left ventricular volume in vitro. BACKGROUND: Three-dimensional echocardiographic systems have been shown to be highly accurate in measuring the volumes of balloon phantoms. However, three-dimensional techniques have not been compared with standard two-dimensional echocardiography in vitro or with cineventriculography, the clinical standard for left ventricular volume measurement. METHODS: Excised porcine hearts were prepared with an internal latex sheath that could be filled and maintained with a known ("true") volume of liquid. Each heart was then imaged by cineventriculography, standard two-dimensional echocardiography and three-dimensional echocardiography. Left ventricular volumes were calculated from 15 hearts at 25 volumes ranging from 50 to 280 ml by the following methods: 1) biplane cineventriculography using the area-length method; 2) two-dimensional echocardiography by the apical biplane method using a summation of discs algorithm in 15 cases and the single-plane, four-chamber method using a summation of discs algorithm in 10 cases; and 3) three-dimensional echocardiography using a polyhedral surface reconstruction volume computation algorithm based on multiple nonparallel, nonevenly spaced short-axis cross sections. RESULTS: Results were compared with true volume, and a nonparametric analysis of variance was performed. Both measurement bias (systematic error) and imprecision (random error) were assessed. All methods tended to underestimate the true volume (two-dimensional echocardiography -6.1 +/- 17.6%, three-dimensional echocardiography -4.7 +/- 5.0% and biplane cineventriculography -3.9 +/- 8.2%), although differences were not significant. Although there was a significant correlation between the magnitude of measurement bias and the size of the volume being measured for two-dimensional echocardiography and cineventriculography, the bias of three-dimensional echocardiography was fairly constant over the range of volumes. When bias was accounted for, two-dimensional echocardiography was significantly less precise than cineventriculography and three-dimensional echocardiography in terms of percent error (15.3 +/- 11.9%, 5.6 +/- 5.7% and 3.9 +/- 3.4%, respectively). CONCLUSIONS: Three-dimensional echocardiography using a polyhedral surface reconstruction algorithm for volume computation provides accuracy comparable to that of biplane cineventriculography in this in vitro model. Standard two-dimensional echocardiographic volume computation is significantly less accurate than the other two methods.

Three-dimensional echocardiography: in vitro and in vivo validation of left ventricular mass and comparison with conventional echocardiographic methods.

OBJECTIVES: This study aimed to validate a method for mass computation in vitro and in vivo and to compare it with conventional methods. BACKGROUND: Conventional echocardiographic methods of determining left ventricular mass are limited by assumptions of ventricular geometry and image plane positioning. To improve accuracy, we developed a three-dimensional echocardiographic method that uses nonparallel, nonintersecting short-axis planes and a polyhedral surface reconstruction algorithm for mass computation. METHODS: Eleven fixed hearts were imaged by three-dimensional echocardiography, and mass was determined in vitro by multiplying the myocardial volume by the density of each heart and comparing it with the true mass. Mass at diastole and systole by three-dimensional echocardiography and magnetic resonance imaging (MRI) was compared in vivo in 15 normal subjects. Ten subjects also underwent imaging by one- and two-dimensional echocardiography, and mass was determined by Penn convention, area-length and truncated ellipsoid algorithms. RESULTS: In vitro results were r = 0.995, SEE 2.91 g, accuracy 3.47%. In vivo interobserver variability for systole and diastole was 16.7% to 27%, 14% to 18.1% and 6.3% to 12.8%, respectively, for one-, two- and three-dimensional echocardiography and was 7.5% for MRI at end-diastole. The latter two agreed closely with regard to diastolic mass (r = 0.895, SEE 11.1 g) and systolic mass (r = 0.926, SEE 9.2 g). These results were significantly better than correlations between MRI and the Penn convention (r = 0.725, SEE 25.6 g for diastole; r = 0.788, SEE 28.7 g for systole), area-length (r = 0.694, SEE 24.2 g for diastole; r = 0.717, SEE 28.2 g for systole) and truncated ellipsoid algorithms (r = 0.687, SEE 21.8 g for diastole; r = 0.710, SEE 24.5 g for systole). CONCLUSIONS: Image plane positioning guidance and elimination of geometric assumptions by three-dimensional echocardiography achieve high accuracy for left ventricular mass determination in vitro. It is associated with higher correlations and lower standard errors than conventional methods in vivo.

Comparison of two- and three-dimensional echocardiography with cineventriculography for measurement of left ventricular volume in patients.

OBJECTIVES: We compared two- and three-dimensional echocardiography with cineventriculography for measurement of left ventricular volume in patients. BACKGROUND: Three-dimensional echocardiography has been shown to be highly accurate and superior to two-dimensional echocardiography in measuring left ventricular volume in vitro. However, there has been little comparison of the two methods in patients. METHODS: Two- and three-dimensional echocardiography were performed in 35 patients (mean age 48 years) 1 to 3 h before left ventricular cineventriculography. Three-dimensional echocardiography used an acoustic spatial locator to register image position. Volume was computed using a polyhedral surface reconstruction algorithm based on multiple nonparallel, unevenly spaced short-axis cross sections. Two-dimensional echocardiography used the apical biplane summation of disks method. Single-plane cineventriculographic volumes were calculated using the summation of disks algorithm. The methods were compared by linear regression and a limits of agreement analysis. For the latter, systematic error was assessed by the mean of the differences (cineventriculography minus echocardiography), and the limits of agreement were defined as +/- 2 SD from the mean difference. RESULTS: Three-dimensional echocardiographic volumes demonstrated excellent correlation (end-diastole r = 0.97; end-systole r = 0.98) with cineventriculography. Standard errors of the estimate were approximately half of those of two-dimensional echocardiography (end-diastole +/- 11.0 ml vs. +/- 21.5 ml; end-systole +/- 10.2 ml vs. +/- 17.0 ml). By limits of agreement analysis the end-diastolic mean differences for two- and three-dimensional echocardiography were 21.1 and 12.9 ml, respectively. The limits of agreement (+/- 2 SD) were +/- 54.0 and +/- 24.8 ml, respectively. For end-systole, comparable improvement was obtained by three-dimensional echocardiography. Results for ejection fraction by the two methods were similar. CONCLUSIONS: Three-dimensional echocardiography correlates highly with cineventriculography for estimation of ventricular volumes in patients and has approximately half the variability of two-dimensional echocardiography for these measurements. On the basis of this study, three-dimensional echocardiography is the preferred echocardiographic technique for measurement of ventricular volume. Three-dimensional echocardiography is equivalent to two-dimensional echocardiography for measuring ejection fraction.

Three-dimensional echocardiography. Advances for measurement of ventricular volume and mass.

There is a need for more accurate and reproducible serial measurement of left ventricular volume and mass in individual subjects by echocardiography. Conventional echocardiography has significant measurement variability because of its use of geometric assumptions and image plane positioning errors. Guided three-dimensional echocardiography eliminates geometric assumptions and reduces image plane positioning errors by using a "line of intersection" display. Use of three-dimensional guided imaging for a one-dimensional measurement of the left ventricle resulted in a threefold improvement of interobserver variability over conventional echocardiographic measurements. Computer-aided three-dimensional reconstruction of the ventricle for ventricular volume from a series of 8 to 10 short-axis images also achieved more than a threefold improvement of interobserver variability compared with two-dimensional echocardiography. Three-dimensional echocardiographic computation of ventricular volume and mass in healthy subjects was achieved with an accuracy comparable to magnetic resonance imaging and was superior to two-dimensional echocardiography. Three-dimensional echocardiography promises to be a more accurate method of estimating left ventricular volume and mass and may be suitable for serial study of individual subjects because of its improved accuracy and decreased interobserver variability compared with conventional echocardiographic methods.

Coronary artery fistula: an abnormality affecting all age groups.

A coronary artery fistula is an abnormal communication between a coronary artery and a cardiac chamber, great vessel, or other vascular structure. It is an infrequent but potentially important abnormality that can affect any age group. Most are congenital in origin, although other etiologies, in particular trauma, have been identified. Many are small and found incidentally during coronary arteriography, while others are identified as the cause of a continuous murmur, myocardial ischemia, congestive heart failure, or, rarely, bacterial endocarditis. The diagnosis should be considered in any patient presenting with a continuous murmur or in the setting of congestive heart failure, myocardial ischemia, or bacterial endocarditis without an obvious etiology. The pathophysiologic mechanisms resulting in symptoms include cardiac volume overload due to the shunting of blood and reduction of the myocardial blood supply due to "coronary steal." The diagnosis of coronary artery fistula may be suggested by the finding of a continuous murmur in a precordial location, which is atypical for patent ductus arteriosus. Two-dimensional echocardiography may demonstrate dilated coronary arteries, and pulse-wave and color-flow Doppler examinations can display turbulent flow in the suspected fistula and its receiving chamber or vessel. Angiography is generally needed to confirm the diagnosis and elucidate anatomic detail. The natural history of coronary artery fistula is variable, with long periods of stability in some patients and gradual progression of symptoms in others. Small fistulas detected incidentally at the time of angiography do not require immediate surgical correction, but careful follow-up is indicated because the potential for enlargement with physiologically important shunting exists and cannot readily be predicted. Spontaneous closure is uncommon. Surgical repair of the fistula is recommended for symptomatic patients and for some without symptoms because a quantitatively small shunt does not predict freedom from future symptoms or complications. Those selected for medical management must be followed closely.

Implications of inferior ST-segment elevation accompanying anterior wall acute myocardial infarction for the angiographic morphology of the left anterior descending coronary artery morphology and site of occlusion.

Inferior ST-segment elevation during anterior wall acute myocardial infarction (AMI) due to left anterior descending (LAD) coronary artery occlusion is unusual and was not previously investigated. This study tested the hypothesis that inferior ST-segment elevation during anterior AMI predicts a specific angiographic morphology that satisfies 2 necessary conditions: (1) mass of ischemic anterior wall myocardium is relatively small, resulting in a weaker anterior injury current and less reciprocal inferior ST-segment depression; and (2) there is concomitant inferior wall transmural ischemia that further shifts the inferior ST segments upward. The study group consisted of 42 consecutive patients with anterior AMI undergoing angiography at 4.1 days (range 0 to 14). Coronary angiograms were examined for 3 features: (1) site of LAD artery occlusion (a distal obstruction implying a smaller mass of ischemic anterior wall myocardium), (2) LAD artery extension onto inferior wall of left ventricle (termed a "wrap around" vessel), and (3) collateral flow from LAD artery to inferior wall. The latter 2 features would be expected to contribute to inferior wall transmural ischemia. Acute inferior ST-segment elevation (sum of ST-segment deviation in leads II, III and aVF greater than or equal to 3.0 mm) was seen in 7 patients (16%). A greater number of LAD artery branches proximal to the site of occlusion was significantly correlated with less inferior ST-segment depression (r = 0.59, p less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Assessment of left ventricular diastolic function after single lung transplantation in patients with severe pulmonary hypertension.

OBJECTIVES: This study was designed to observe left ventricular filling by Doppler echocardiography before and after single lung transplantation in patients with severe pulmonary hypertension. BACKGROUND: Right ventricular pressure overload causes the deformation of the left ventricle by septal flattening toward its cavity, which may result in impaired left ventricular early filling. Recent studies have demonstrated the ability of single lung transplantation to restore right ventricular function in patients with severe pulmonary hypertension. However, changes in left ventricular filling after single lung transplantation have not been well studied. METHODS: We performed Doppler echocardiography in nine patients with severe pulmonary hypertension before, early (<3 months), and late (>1 year) after single lung transplantation. The study group consisted of eight female patients and one male patient with mean age of 32 years (range, 15 to 48 years). Six patients were diagnosed as having primary pulmonary hypertension and three as having secondary pulmonary hypertension. Nine age-matched normal subjects served as a control group. Doppler measurements included the following: transmitral flow early (E) and atrial (A) velocities, integrals (Ei and Ai), and left ventricular isovolumic relaxation time. The ratio of E/A and atrial filling fraction (Ai/Ei+Ai, AFF) were also determined. Left ventricular geometry was assessed from mid-short axis view with a circular shape factor (CSF). RESULTS: Early after lung transplantation, the left ventricular geometry became more circular with CSF (mean+/-SD) increasing from 0.63+/-0.09 to 0.88+/-0.05 (p<0.05). However, impaired early filling persisted in the patient group (E/A 0.7+/-0.1 vs preoperative 0.6+/-0.1, AFF 0.61+/-0.1 vs 0.64+/-0.1; both p=not significant). One year later, the left ventricular filling had returned to normal range with E/A 1.4+/-0.6 and AFF 0.35+/-0.1. CONCLUSIONS: This study observed that the impaired left ventricular early filling persisted shortly after single lung transplantation in patients with severe pulmonary hypertension, despite findings that left ventricular geometry was restored earlier after reversal of pulmonary hypertension. The abnormal filling pattern appeared to be resolved 1 year later. The findings suggest the impaired early filling may be caused by intrinsic left ventricular abnormalities other than ventricular interaction in these patients.

Three-dimensional echocardiography compared to two-dimensional echocardiography for measurement of left ventricular mass anatomic validation in an open chest canine model.

A three-dimensional echocardiographic system has been developed that can accurately compute left ventricular mass in vitro. This study was designed to validate the new echocardiographic system for the measurement of left ventricular mass in vivo and to compare the accuracy of three-dimensional echocardiography to the accuracy of conventional two-dimensional echocardiography for measuring left ventricular mass. Echocardiographic imaging was performed 6 h following coronary ligation in 20 open chest dogs, at which time the heart was excised and the left ventricle weighed. Three-dimensional echocardiography used multiple short axis sections and polyhedral surface reconstruction to compute myocardial volume. The two dimensional methods employed the truncated ellipsoid model and the area-length model. Myocardial volume was multiplied by 1.05 g/cc and echocardiographic mass estimates were compared to the true left ventricular weight. Three-dimensional echocardiography provided the best correlation (r = 0.96, upsilon r = 0.88 and r = 0.83 for the truncated-ellipsoid and area-length methods, respectively), and the lowest standard error of the estimate for the regression equation (+/- 5.5 g upsilon +/- 11.0 and +/- 14.6 g, respectively). Three dimensional echocardiography also had the lowest standard deviation for the echo-true mass differences (+/- 5.8 g upsilon +/- 10.7 g and +/- 14.2 g) and a lower root mean square percent error (6.8%) upsilon 12.6% and 12.7%). In this open chest canine model, three-dimensional echocardiography is more accurate than standard two-dimensional echocardiographic methods for measuring left ventricular mass.

Arterial desaturation and orthodeoxia after atrial septal defect repair: demonstration of the mechanism by transesophageal and contrast echocardiography.

A young woman without symptoms underwent repair of an ostium secundum atrial septal defect, and exertional dyspnea developed postoperatively. This was found to be due to arterial oxygen desaturation which was exaggerated in the upright position and with exercise. Contrast echocardiography confirmed a right-to-left shunt at the atrial level that was shown only with femoral venous contrast injection and not with upper extremity venous injection. Transesophageal echocardiography and subsequent surgical exploration found that the Eustachian valve had been mistaken for the inferior rim of the defect and sutured to the upper rim of the defect. This created a channel through which blood from the inferior vena cava could be partially deferred to the left atrium.

Three-dimensional echocardiography: limitations of apical biplane imaging for measurement of left ventricular volume.

A new three-dimensional echocardiographic system creates a "line of intersection" display to allow precise and known positioning of echocardiographic images. Our purpose was to determine whether use of the line-of-intersection display will improve positioning of the apical four-chamber and apical two-chamber views and thereby improve the agreement between estimates of left ventricular volume by apical biplane echocardiography and cineventriculography. Unguided and line of intersection-guided apical biplane views were obtained in 31 patients immediately before cardiac catheterization and single-plane cineventriculography. In 15 patients the line-of-intersection display was used to measure the position of the image plane in studies of unguided and guided methods. Linear regression and limits of agreement analysis were used to assess the agreement between cineventriculographic volumes and echocardiographic volumes determined from each set of images. The Wilcoxon test was used to compare guided and unguided image positioning. The line-of-intersection display improved four-chamber and two-chamber view positioning closer to the center of the ventricle and rotation closer to orthogonal positioning. Guided-image positioning was not able to correct displacement of the ultrasound beam anterior to the ventricular apex without deterioration of image quality in most patients. Despite improvements in image plane positioning, the agreement between echocardiographic and cineventriculographic volumes was unchanged. For end-diastole views, the unguided images had an r value = 0.84, standard error of the estimate of +/- 23.0 cc, and limits of agreement of +/- 62.4 cc. Corresponding values for the guided images at end diastole were r = 0.85, standard error of the estimate of +/- 22.9 cc, and limits of agreement of +/- 60.8 cc. At end systole the unguided results were r = 0.91, standard error of the estimate of 16.8 cc, and limits of agreement of +/- 52.2 cc. The line-of-intersection guiding of image plane positioning can improve apical image positioning but does not improve the agreement between apical biplane echocardiographic and cineventriculographic left ventricular volumes. The optimal apical imaging window is frequently occluded by the rib cage, resulting in a decrease in image quality. This reduction of image quality, combined with assumptions of left ventricular geometry, limit the accuracy of estimates of left ventricular volume from apical biplane echocardiography.

Three-dimensional echocardiographic volume computation: in vitro comparison to standard two-dimensional echocardiography.

Two-dimensional (2D) echocardiographic methods for quantitative left ventricular volume computation have been shown to have a low predictive accuracy and reproducibility. To address the problem of geometric assumptions and image plane positioning errors inherent in 2D echocardiography, three-dimensional (3D) echocardiographic systems have been constructed that provide spatial registration and display of transducer-image position and orientation. Although 3D echocardiography has been shown to accurately measure volume in vitro and in vivo, only preliminary data exist demonstrating its superiority over standard 2D echocardiography. We calculated the volume of 30 water-filled latex balloon phantoms of varying size (40 to 200 ml) and shape using each method. Fifteen phantoms were nondistorted (ellipsoid or pear shaped); 15 were symmetrically distorted (dumbbell shaped). Although both 2D and 3D echocardiography showed an excellent correlation to the true volume (r = 0.97 and 0.99, respectively), the standard error of the estimate for 2D echocardiography was twofold larger than for 3D echocardiography (SEE = 6.7 ml and 3.52 ml, respectively). The true volume was slightly underestimated by 3D echocardiography (-2.83 ml), whereas 2D echocardiography overestimated a similar amount (+2.87 ml). The accuracy and variability for 2D echocardiography were significantly poorer (5.22% +/- 5.66% and 5.29% +/- 5.6%, p = 0.001 and 0.002, respectively) as compared with 3D echocardiography (3.7% +/- 2.65% and 2.65% +/- 1.9%, respectively). We conclude that 3D echocardiography with guided image plane positioning and a novel algorithm for volume computation (polyhedral surface reconstruction) achieves significantly more accurate and reproducible results than conventional 2D echocardiography with the modified Simpson's rule.(ABSTRACT TRUNCATED AT 250 WORDS)

Reduction in injection pain using buffered lidocaine as a local anesthetic before cardiac catheterization.

Previous reports have suggested that pain associated with the injection of lidocaine is related to the acidic pH of the solution. To determine if the addition of a buffering solution to adjust the pH of lidocaine into the physiologic range would reduce pain during injection, we performed a blinded randomized study in patients undergoing cardiac catheterization. Twenty patients were asked to quantify the severity of pain after receiving standard lidocaine in one femoral area and buffered lidocaine in the opposite femoral area. The mean pain score for buffered lidocaine was significantly lower than the mean score for standard lidocaine (2.7 +/- 1.9 vs. 3.8 +/- 2.2, P = 0.03). The pH adjustment of standard lidocaine can be accomplished easily in the catheterization laboratory before injection and results in a reduction of the pain occurring during the infiltration of tissues.