Validation of real-time three-dimensional echocardiography for quantifying left ventricular volumes in the presence of a left ventricular aneurysm: in vitro and in vivo studies

OBJECTIVES

To validate the accuracy of real-time three-dimensional echocardiography (RT3DE) for quantifying aneurysmal left ventricular (LV) volumes.

BACKGROUND

Conventional two-dimensional echocardiography (2DE) has limitations when applied for quantification of LV volumes in patients with LV aneurysms.

METHODS

Seven aneurysmal balloons, 15 sheep (5 with chronic LV aneurysms and 10 without LV aneurysms) during 60 different hemodynamic conditions and 29 patients (13 with chronic LV aneurysms and 16 with normal LV) underwent RT3DE and 2DE. Electromagnetic flow meters and magnetic resonance imaging (MRI) served as reference standards in the animals and in the patients, respectively. Rotated apical six-plane method with multiplanar Simpson's rule and apical biplane Simpson's rule were used to determine LV volumes by RT3DE and 2DE, respectively.

RESULTS

Both RT3DE and 2DE correlated well with actual volumes for aneurysmal balloons. However, a significantly smaller mean difference (MD) was found between RT3DE and actual volumes (-7 ml for RT3DE vs. 22 ml for 2DE, p = 0.0002). Excellent correlation and agreement between RT3DE and electromagnetic flow meters for LV stroke volumes for animals with aneurysms were observed, while 2DE showed lesser correlation and agreement (r = 0.97, MD = -1.0 ml vs. r = 0.76, MD = 4.4 ml). In patients with LV aneurysms, better correlation and agreement between RT3DE and MRI for LV volumes were obtained (r = 0.99, MD = -28 ml) than between 2DE and MRI (r = 0.91, MD = -49 ml).

CONCLUSIONS

For geometrically asymmetric LVs associated with ventricular aneurysms, RT3DE can accurately quantify LV volumes.

Results of the double switch operation in the current era

BACKGROUND

In patients with atrioventricular and arterioventricular discordance congenitally corrected transposition, the morphologically right ventricle may progressively deteriorate while functioning in the systemic circuit. The double switch operation has been proposed to limit this functional deterioration.

METHODS

From October 1993 to August 1998, the records of 27 patients with congenitally corrected transposition were reviewed. Age at operation ranged from 3 months to 55 years. Associated defects included ventricular septal defects in 18, pulmonary atresia in 7, and pulmonary stenosis in 11 patients. Twenty-two patients had double switch operations (10 arterial switch plus Senning procedures and 12 Rastelli plus Senning procedures). Five patients were not candidates for the double switch. Before the double switch, 6 patients required pulmonary artery banding and 10 had functioning systemic to pulmonary artery or cavopulmonary shunts.

RESULTS

There was no early or late mortality. Two patients required pacemaker implantation, both later regained normal sinus rhythm. Tricuspid valve function improved in all patients except one. Moderate left ventricular dysfunction developed 5 months postoperatively in 1 patient.

CONCLUSIONS

The double switch operation can be performed in selected patients with minimal early morbidity and mortality. Longer follow-up is necessary to determine whether this complex approach is indeed warranted.

New digital measurement methods for left ventricular volume using real-time three-dimensional echocardiography: comparison with electromagnetic flow method and magnetic resonance imaging

AIM

The aim of this study was to investigate the feasibility and accuracy of using symmetrically rotated apical long axis planes for the determination of left ventricular (LV) volumes with real-time three-dimensional echocardiography (3DE).

METHODS AND RESULTS

Real-time 3DE was performed in six sheep during 24 haemodynamic conditions with electromagnetic flow measurements (EM), and in 29 patients with magnetic resonance imaging measurements (MRI). LV volumes were calculated by Simpson's rule with five 3DE methods (i.e. apical biplane, four-plane, six-plane, nine-plane (in which the angle between each long axis plane was 90 degrees, 45 degrees, 30 degrees or 20 degrees, respectively) and standard short axis views (SAX)). Real-time 3DE correlated well with EM for LV stroke volumes in animals (r=0.68-0.95) and with MRI for absolute volumes in patients (r-values=0.93-0.98). However, agreement between MRI and apical nine-plane, six-plane, and SAX methods in patients was better than those with apical four-plane and bi-plane methods (mean difference = -15, -18, -13, vs. -31 and -48 ml for end-diastolic volume, respectively, P<0.05).

CONCLUSION

Apically rotated measurement methods of real-time 3DE correlated well with reference standards for calculating LV volumes. Balancing accuracy and required time for these LV volume measurements, the apical six-plane method is recommended for clinical use.

Initial clinical experience of real-time three-dimensional echocardiography in patients with ischemic and idiopathic dilated cardiomyopathy

The geometry of the left ventricle in patients with cardiomyopathy is often sub-optimal for 2-dimensional ultrasound when assessing left ventricular (LV) function and localized abnormalities such as a ventricular aneurysm. The aim of this study was to report the initial experience of real-time 3-D echocardiography for evaluating patients with cardiomyopathy. A total of 34 patients were evaluated with the real-time 3D method in the operating room (n = 15) and in the echocardiographic laboratory (n = 19). Thirteen of 28 patients with cardiomyopathy and 6 other subjects with normal LV function were evaluated by both real-time 3-D echocardiography and magnetic resonance imaging (MRI) for obtaining LV volumes and ejection fractions for comparison. There were close relations and agreements for LV volumes (r = 0.98, p <0.0001, mean difference = -15 +/- 81 ml) and ejection fractions (r = 0.97, p <0.0001, mean difference = 0.001 +/- 0.04) between the real-time 3D method and MRI when 3 cardiomyopathy cases with marked LV dilatation (LV end-diastolic volume >450 ml by MRI) were excluded. In these 3 patients, 3D echocardiography significantly underestimated the LV volumes due to difficulties with imaging the entire LV in a 60 degrees x 60 degrees pyramidal volume. The new real-time 3D echocardiography is feasible in patients with cardiomyopathy and may provide a faster and lower cost alternative to MRI for evaluating cardiac function in patients.

Angina and coronary ostial lesions in a young woman as a presentation of Takayasu's arteritis

Diagnostic considerations in young patients presenting with coronary artery disease have conventionally included familial dyslipidemias, lipoprotein(a) elevation, hyperhomocysteinemia, cocaine toxicity, hypercoagulable states, connective tissue disorders, vasculitis and the presence of other established risk factors for coronary artery disease. The case of a young woman with unstable angina and a left main coronary artery ostial lesion on cardiac catheterization is discussed. She was subsequently diagnosed with Takayasu's arteritis 4 years later.

The clinical application of 'edema-weighted' magnetic resonance imaging in the assessment of Takayasu's arteritis

Takayasu's arteritis is an inflammatory process affecting medium to large arteries. In about half of cases, constitutional symptoms and laboratory studies do not correlate with disease activity, confounding therapeutic decision making. We present six representative cases of Takayasu's arteritis in which new magnetic resonance imaging sequences for improved morphological and tissue characterization were useful in identifying aortic wall thickening and acute inflammatory changes, respectively. Specifically, fast spin-echo sequences designed to enhance detection of vessel wall edema were included. This information proved useful in guiding clinical decision making, particularly in regard to initiation and monitoring of therapy in our patients.

Right ventricular arrhythmia in the absence of arrhythmogenic dysplasia: MR imaging of myocardial abnormalities

PURPOSE

To evaluate right ventricular abnormalities with magnetic resonance (MR) imaging in patients with arrhythmia but without arrhythmogenic dysplasia.

MATERIALS AND METHODS

In 53 patients being evaluated for right ventricular arrhythmia and 15 control subjects, MR imaging was performed to evaluate fixed thinning, fatty replacement, or reduced systolic wall thickening or motion. A diagnosis of idiopathic right ventricular outflow tract tachycardia or indeterminate was assigned for each patient, and the severity of arrhythmia was categorized.

RESULTS

Right ventricular abnormalities were revealed in 32 (60%) of the 53 patients: fixed thinning in 27 (84%), fatty replacement in eight (25%), and reduced wall thickening or motion in 31 (97%). Right ventricular abnormalities were found in 35 (76%) of 46 patients with idiopathic right ventricular outflow tract tachycardia and in seven (39%) of 18 patients with indeterminate diagnoses (P = .022).

CONCLUSION

Mild right ventricular abnormalities are likely sources for arrhythmias, even in the absence of arrhythmogenic right ventricular dysplasia.

Intramural hematoma of the thoracic aorta: MR image findings and their prognostic implications

PURPOSE

To evaluate magnetic resonance (MR) imaging findings of intramural hematoma of the thoracic aorta and their relationship to prognosis.

MATERIALS AND METHODS

MR images of 22 patients with intramural hematoma of the thoracic aorta were reviewed retrospectively. Site, thickness, degree of mural involvement, and signal intensity on spin-echo (SE) and cine gradient-echo (GRE) images of the hematoma were noted. MR findings of patients who did and those who did not develop complications were compared.

RESULTS

Hematoma site was the only MR finding that correlated significantly with patient outcome. Complication frequencies in four (80%) of five patients with hematoma of the ascending aorta (type A) and in two (12%) of 17 patients with hematoma of the descending aorta (type B) were significantly different (P = .009). There were moderately strong correlations between days after symptom onset and signal intensity of the hematoma on SE (r = 0.78) and GRE (r = 0.72) images. MR images of two of three patients who developed early-subacute complications showed signal intensity changes of the hematoma that were consistent with recurrent bleeding.

CONCLUSION

Patients with MR findings consistent with type A intramural hematoma of the thoracic aorta should undergo surgery. In cases of type B intramural hematoma of the thoracic aorta, MR imaging can be useful for detecting complete resolution or impending complications of the hematoma.

MR imaging of the thoracic aorta

The evaluation and diagnosis of thoracic aortic disease using magnetic resonance imaging, including magnetic resonance angiography, is assuming an increasing role in clinical practice. Comparison with other modalities, including computed tomography and echocardiography, is discussed. Newer magnetic resonance imaging techniques, including 3-D breath-hold time-of-flight sequences are highlighted, as well as imaging strategies using standard magnetic resonance imaging techniques. Thoracic aortic disease entities covered include aneurysm, dissection, penetrating ulcers and intramural hematoma, aortitis and infection, tumors, and congenital aortic disease.

Comparison of painful and painless left ventricular dysfunction recorded during ambulatory ventricular function monitoring in angina pectoris secondary to coronary artery disease

Left ventricular (LV) function and the electrocardiogram of 55 patients with coronary artery disease and angina were monitored for a mean of 3.2 +/- 1.9 hours with an ambulatory LV function monitor. During the monitoring interval, patients performed daily activities such as sitting, walking, climbing stairs, and eating. Sixty episodes of transient reduction in ejection fraction of > 5% lasting > 60 seconds were observed in 24 patients; 13 episodes were associated with typical angina, but 47 were asymptomatic. Asymptomatic episodes had a shorter duration of ventricular dysfunction (116 +/- 49 vs 189 +/- 113 seconds; p < 0.05), and smaller increases in relative end-diastolic and end-systolic volumes (end-diastolic 0.9 +/- 5.4% vs 4.6 +/- 4.9% [p < 0.05], and end-systolic 21 +/- 11% vs 35 +/- 20% [p < 0.05]) than did symptomatic ones. When a subset of patients with both symptomatic and asymptomatic episodes were analyzed, similar results were observed: in asymptomatic episodes, duration was shorter (82 +/- 31 vs 200 +/- 110 seconds; p < 0.005), ejection fraction decrease was smaller (-7.3 +/- 2.6% vs -11.0 +/- 4.7%; p < 0.05), and end-systolic volume increase was smaller (23 +/- 12% vs 37 +/- 19%; p < 0.05). The data suggest that asymptomatic transient LV dysfunction is less severe and of shorter duration in patients with angina pectoris.

Temporal relation between left ventricular dysfunction and chest pain in coronary artery disease during activities of daily living

Forty-three ambulatory patients with angina of increasing frequency underwent continuous monitoring of left ventricular (LV) function for an average of 2.9 +/- 1.9 hours to determine the incidence and temporal sequence of LV dysfunction, ST-segment depression and chest pain. Indicators of ischemia were: a decrease in ejection fraction greater than 5% lasting greater than 1 minute; horizontal or downsloping ST-segment depression of greater than or equal to 1 mm; or onset of the patient's typical chest pain complex, or a combination of these. During the monitoring interval, subjects performed daily activities such as sitting, walking, climbing stairs and eating. In 11 patients, 22 episodes of chest pain or ST-segment depression, or both, were observed. Eighteen episodes were accompanied by a decrease in ejection fraction (9 patients); chest pain accompanied the decrease in ejection fraction during 13 episodes, whereas ST-segment changes occurred during 7. In 12 of 13 episodes the decrease in ejection fraction began earlier than the onset of chest pain, whereas in 1 patient ejection fraction decrease and chest pain onset started at the same time. The average interval from a decrease in ejection fraction to the onset of chest pain was 56 +/- 41 seconds (range 0 to 120). ST changes occurred after the onset of a decrease in ejection fraction in 6 of 7 episodes. The average interval from the onset of ejection fraction decrease and the onset of ST change was 99 +/- 91 seconds. These data suggest that LV dysfunction manifested by a decrease in ejection fraction is an earlier indicator of myocardial ischemia than is angina pectoris or electrocardiographic evidence of ischemia.

Redistribution of regional and organ blood volume and effect on cardiac function in relation to upright exercise intensity in healthy human subjects

To determine the effect of relative exercise intensity on organ blood volume and its relation to cardiac function, changes in relative blood volume and cardiac function were monitored with radionuclide techniques in 14 healthy volunteers. After labeling the subject's red cells with technetium 99m, we acquired data at rest, zero-load cycling, and at 50%, 75%, and 100% of maximal oxygen uptake. From rest to zero-load cycling, leg blood volume decreased 32 +/- 2% (mean +/- SEM), whereas relative end-diastolic blood volume increased 9.6 +/- 1.2%, and lung blood volume increased 18 +/- 2%, suggesting that the lungs may act as a blood volume buffer during periods of acutely increased venous return. With relative increasing exercise, leg blood volume stabilized, and then the blood volume in the abdominal organs decreased, further augmenting cardiopulmonary blood volume; leg blood volume and abdominal blood volume decreased by 23 +/- 2% and 19 +/- 2% from baseline, respectively, whereas thoracic blood volume increased 38 +/- 4%. In the abdomen, large decreases in blood volume were observed in the spleen (46 +/- 2%), kidney (24 +/- 4%), and liver (18 +/- 4%). In contrast, lung blood volume increased 50 +/- 4%, with the upper lung fields increasing more than the lower. Blood sampling revealed an increase in the hematocrit level by 4.3 +/- 0.4 units at peak exercise that paralleled the decrease in splenic blood volume (r2 = -0.64, p less than 0.001), suggesting a role for the spleen in augmenting cardiovascular performance by the release of concentrated red blood cells into general circulation. We conclude that upright exercise results in marked blood volume shifts from the legs and abdominal organs to the heart and lungs in a dynamic process correlating closely with oxygen consumption.