Left ventricular volume calculations using a multiplanar transoesophageal echoprobe; in vitro validation and comparison with biplane angiography.

BACKGROUND: Biplane angiographic and transthoracic echocardiographic volume calculations have shown to be sufficiently reliable in symmetric hearts; however, they are unreliable in the presence of aneurysmatic distortions. Multiplane transoesophageal echocardiography offers unobstructed cross-sectional views of the heart from one stable transducer position with the potential of imaging irregular cavity forms more accurately. It was the purpose of this in vitro study to compare the precision of multiplanar transoesophageal echocardiography to that of biplane angiography in determining left ventricular volumes, especially in aneurysmatic models. METHODS: Seven silicon rubber models of the left ventricle from post-mortem specimens (four with aneurysms) were filled with 30 different volumes (range 153-256 ml, 197 +/- 30 ml). Echocardiographic cross-sections (20 degree rotational steps) were obtained from different transducer positions, utilizing a multiplanar probe with a central rotational axis. Volumes were calculated using the disc-summation method. For comparison the same volumes were determined by standard biplane angiography. The minimum number of echo cross-section necessary to optimize precision was analysed by calculating volumes for each increasing equidistant rotational step. RESULTS: Linear correlation between measured volume using a multiplanar transoesophageal echoprobe and true volume was high (r = 0.97) and significantly better than for biplane angiography (r = 0.88; P < 0.001). Measurement bias and imprecision were also significantly lower with multiplanar echocardiography than with biplane angiography (3.9 +/- 7.1% vs 11.1 +/- 15.4%, and 2.0 +/- 3.7% vs 5.9 +/- 8.3%; P < 0.001). Precision of biplane angiographic volume measurements was significantly influenced by the presence of aneurysmatic distortions. Multiplanar echo volumes, however, were not influenced by left ventricular geometry and transducer positions. Nine echo cross-sections provided optimal precision. CONCLUSIONS: Three-dimensional echocardiographic volume calculations using a multiplanar transoesophageal echoprobe and the disc-summation method provide precise measurements unaffected by left ventricular geometry and transducer position in an in vitro setting. Standard biplane angiography is significantly less precise.

Occurrence of transcranial Doppler high-intensity transient signals in patients with potential cardiac sources of embolism. A prospective study.

BACKGROUND AND PURPOSE: Cerebral emboli can be recognized by typical "high-intensity transient signals" (HITS) in the transcranial Doppler (TCD) spectral curves. Patients with potential cardiac sources of embolism are at higher risk for stroke. METHODS: We examined the frequency of HITS in the left middle cerebral artery (MCA) with TCD over periods of 30 minutes in 100 patients having potential cardiac sources of embolism, as indicated by transthoracic or transesophageal echocardiography. RESULTS: Thirty-six (36%) of the patients presented with HITS. Sex, age, sufficient anticoagulation level, antiplatelet therapy, neurological symptoms, and a history of thrombosis had no influence on the prevalence and number of HITS. The patients with a single echocardiographic diagnosis were separated into eight echocardiographically defined groups: patients with (1) atrial fibrillation, (2) coronary artery disease plus ejection fraction of more than 30% including at least three wall segments of hypokinesia/akinesia, (3) coronary artery disease with less than 30% ejection fraction, (4) dilated cardiomyopathy, (5) infectious endocarditis, (6) aortic stenosis, (7) mitral stenosis, and (8) patent foramen ovale. A significant difference in HITS occurrence could not be found in any of the defined groups. Only patients with infectious endocarditis showed a tendency for a higher HITS prevalence. CONCLUSIONS: HITS are common phenomena in patients with potential cardiac sources of embolism. The clinical relevance of these HITS remains unclear.

[3-dimensional reconstruction of multiplanar transesophageal echocardiography images: a methodologic report with case examples]. / Dreidimensionale Rekonstruktion multiplaner transösophagealer echokardiographischer Schnittbilder: Ein Methodenbericht mit Fallbeispielen.

First experience with the dynamic three-dimensional reconstruction of transesophageal echocardiographic images in more than 100 patients with various cardiac diseases are reported. Ninety different two-dimensional image planes were acquired for each reconstruction using a conventional multiplanar transducer, connected to a stepper motor and controlled by a computer-based image acquisition system with special software. Acquisition time for one data set was 2.3 +/- 0.9 min, and calculation time to achieve three-dimensional images was 20-45 min. Several cardiac structures were reconstructed and analyzed qualitatively and quantitatively (measurements of distances and areas, volume calculation by Simpson's rule). Image sequences showing three-dimensional depth by gray scale modification were generated. After image acquisition one can select any desired cut plane to achieve perspectives that cannot be obtained by two-dimensional technique. Advantages of three-dimensional echocardiography are the display and potential quantification of pathomorphology of the left ventricle and mitral valve, atrial septal defects, intracardiac masses (i.e., myxomas, vegetations), and direct spatial imaging of complex congenital heart diseases. In principle, three-dimensional data sets have advantages for the quantitative evaluation of irregular formed cardiac structures, since the three-dimensional data set is more complete than cross-sections used in conventional two-dimensional echocardiography. Currently, however, these advantages are limited by the necessity of human interaction to segment the structures of interest.

[Improved evaluation of prosthetic heart valve regurgitation with multiplanar transesophageal echocardiography]. / Bessere Beurteilung von Klappenprotheseninsuffizienzen mit der multiplanen transösophagealen Echokardiographie.

UNLABELLED: To study the value of the newly introduced multiplane transesophageal transducer technology for the assessment of prosthetic valve regurgitation, 63 consecutive patients with 35 mitral and 33 aortic prostheses (23 bioprostheses and 45 mechanical prostheses) were examined. Transvalvular, paravalvular, and, in mechanical valves, normal or pathological transvalvular regurgitation were identified using first 0 degrees (transverse) and 90 degrees (longitudinal) planes combined with flexion of the echoscope tip and then additionally using multiple intermediary planes by transducer rotation. In a subgroup of 20 patients interobserver variability was evaluated. Both methods showed regurgitation in 56/58 valves; one additional case of regurgitation was seen by multiplane imaging only. However, there were 19 cases of regurgitation not clearly classifiable by biplane technique compared to only three using multiplane technique. Grading of severity was concordant by both modalities in 66 and discordant in only two cases. Observers disagreed on severity in 2/20 cases based on biplane imaging, but in none based on multiplane imaging; classification of regurgitation differed in 6/20 biplane and 1/20 multiplane images respectively. CONCLUSION: Multiplane transesophageal imaging improves classification of prosthetic regurgitation, but has little effect on severity grading.

Incremental value of biplane and multiplane transesophageal echocardiography for the assessment of active infective endocarditis.

In 41 patients with clinical evidence of active infective endocarditis, transesophageal echocardiography was performed in a stepwise manner, starting with evaluation of the monoplane views, followed by the longitudinal plane, and finally by the intermediate planes. Number, location, length, area, density, extent, and mobility of vegetations and abscesses were assessed in the monoplane, biplane, and best intermediate planes to identify and quantify the incremental value of the longitudinal and intermediate planes. Eighty-three vegetations and 6 abscesses were found. In 4 patients (10%) monoplane evaluation yielded false-negative results. There were no false-negative results using the biplane evaluation. However, when compared with multiplane evaluation, additional vegetations were missed in 23% of patients after monoplane and in 9% of patients after biplane evaluation. Three abscesses were missed using the monoplane and 1 was missed using the biplane technique. The area was underestimated in 60% of all vegetations (mean underestimation, 37% +/- 23% [SD] of maximal area) and length in 49% of cases (mean underestimation, 38% +/- 23% [SD] of maximal length) of all vegetations when biplane was compared with multiplane evaluation. Also, with monoplane and biplane evaluation, mobility and density were misinterpreted in 6% and 5% and 17% and 9% of all vegetations, respectively. Thus, multiplane transesophageal echocardiography is more accurate than the monoplane and biplane techniques in assessing patients with active infective endocarditis.

Three-dimensional reconstruction of cardiac structures from transesophageal echocardiography.

Although tomographic imaging has been very successful in cardiology,the quantitation of volumes, surfaces, and masses,as well as understanding of complex morphologies would improve by three-dimensional imaging. This review focuses on approaches to 3-D reconstruction from transesophageal echocardiography. In the past, several attempts using either stepwise parallel translation or stepwise rotation of the transducer have been made. In vitro and, to a limited extent, in vivo studies have confirmed high accuracy in calculating left ventricular volumes in such manner. Complex cardiac structures and their motion, such as the mitral annulus, mitral leaflets, atrial septal defects, and others have been reconstructed from patient studies. Although potentially a powerful tool for cardiac imaging with promising quantitation capabilities, progress is needed in particular in the field of border detection to make 3-D imaging practical enough for clinical use.

Does multiplane transesophageal echocardiography improve the assessment of prosthetic valve regurgitation?

Assessment of prosthetic valve regurgitation by echocardiography remains difficult. To study the value of the newly introduced multiplane transesophageal technology for this purpose, prosthetic valve regurgitation was examined in 63 consecutive patients with 35 mitral and 33 aortic prostheses (23 bioprostheses and 45 mechanical prostheses). Transvalvular, paravalvular and, in mechanical valves, normal or pathologic transvalvular regurgitation were identified first with 0 degrees (transverse) and 90 degrees (longitudinal) planes combined with flexion of the echoscope tip and then additionally with multiple intermediary planes by transducer rotation. In a subgroup of 20 patients interobserver variability was evaluated. Both methods showed regurgitation in 56 of 68 valves; one additional case of regurgitation was seen by multiplane imaging only. However, 19 cases of regurgitation were not clearly classifiable by biplane transesophageal echocardiography compared with only three with multiplane transesophageal echocardiography. Grading of severity was concordant by both modalities in 66 and discordant in only two cases. Observers disagreed on severity in two of 20 cases based on biplane imaging but in none based on multiplane imaging; classification of regurgitation differed in six of 20 (biplane) and one of 20 (multiplane), respectively. Multiplane transesophageal imaging improves classification of prosthetic regurgitation but has little effect on severity grading.

Comparison of transcranial contrast Doppler sonography and transesophageal contrast echocardiography for the detection of patent foramen ovale in young stroke patients.

The prevalence of a patent foramen ovale was assessed by simultaneously performing transesophageal contrast echocardiography and transcranial contrast Doppler sonography (TCD) in 137 subjects (mean age 36 years) with stroke of unclarified etiology (n = 41), clarified etiology (n = 33), and in normal subjects (n = 63; mean age 32 years). Patent foramen ovale was found significantly more often in patients with unclarified than clarified strokes or in normal subjects (66% vs 33%, or 43%). Massive paradoxical embolism through a patent foramen ovale, identified by TCD, occurred significantly (p < 0.01) more often in patients with unclarified (64%) than clarified (27%) strokes or in normal subjects (3%). However, minimal shunts were typical in normal subjects (79%). Patent foramen ovale was detected indirectly by TCD when calculated on the basis of transesophageal contrast echocardiographic findings (sensitivity 89%, specificity 92%). Thus, TCD reliably detects paradoxical cerebral embolism through a patent foramen ovale, and provides important additional information for evaluating its clinical relevance by semi-quantification of embolic contrast material.

Hyperinsulinism in patients with coronary artery disease.

AIM: To assess the clinical impact of hyperinsulinism and major coronary risk factors in patients with angiographically documented or excluded coronary artery disease (CAD), a clinical study was carried out in 268 men admitted for left heart catheterization. METHODS: Fasting immunoreactive insulin (IRI) levels were correlated to all major cardiovascular risk factors and to the presence and degree of CAD. RESULTS: IRI levels were correlated significantly with the degree of CAD (one-vessel disease: mean IRI 9.45 microU/ml +/- 0.43 SEM; two-vessel disease: mean IRI 10.4 microU/ml +/- 0.71 SEM; three-vessel disease: mean IRI 11.88 microU/ml +/- 0.98 SEM) and inversely to the high-density lipoprotein level (P < 0.05). In patients with arterial hypertension, IRI levels were elevated, without a significant difference between those with and those without CAD, whereas the IRI levels of non-hypertensive men with CAD (n = 81; mean IRI 9.85 microU/ml +/- 0.51 SEM) differed significantly (P < 0.05) from those of non-hypertensive men without CAD (n = 59; mean IRI 7.76 microU/ml +/- 0.43 SEM). IRI levels were significantly higher (P < 0.05) in obese patients (n = 65; mean IRI 11.68 microU/ml +/- 0.70 SEM versus n = 203; mean IRI 9.32 microU/ml +/- 0.34 SEM), in patients with elevated triglycerides (n = 58 mean IRI 11.59 microU/ml +/- 0.81 SEM versus n = 210; mean IRI 9.42 microU/ml +/- 0.33 SEM), and in patients with lowered HDL cholesterol (n = 178; mean IRI 11.06 microU/ml +/- 0.63 SEM versus n = 90; mean IRI 9.29 microU/ml +/- 0.34 SEM). Diabetic patients on angiotensin converting enzyme inhibitor therapy (n = 11; mean IRI 7.91 microU/ml +/- 0.91 SEM) had significantly (P < 0.05) lower IRI levels than those not treated with ACE inhibitors (n = 25; mean IRI 12.96 microU/ml +/- 1.47 SEM). IRI levels exceeding 8 microU/ml were associated with a 1.98-fold risk for CAD compared with IRI levels below 8 microU/ml. Stepwise logistic regression showed that insulin was an independent determinant of CAD. CONCLUSION: Knowledge of the fasting insulin level is an important contribution to the identification of patients with, or at risk of, CAD.

Combined subtotal pancreatectomy with selective streptozotocin infusion--a model for the induction of insulin deficiency in dogs.

Standardized models of type I diabetes-like insulin deficiency in larger laboratory animals hardly exist. It was therefore investigated whether stable long-term insulin deficiency in dogs can be induced by selective beta-cell destruction in a safe and reliable procedure without damage of other organs. In Beagle dogs, the diabetogenic response to systemic streptozotocin administration (38.5-28 mg/kg b.wt.) was tested. In addition, resection of corpus and cauda pancreatis in combination with selective streptozotocin perfusion (25 mg/kg b.wt.) of the remaining pancreas tissue was evaluated. Whereas systemic streptozotocin administration failed to destroy insulin secretion, but led to a variety of intoxication symptoms even in comparatively low doses (28 mg/kg b.wt.), the latter procedure resulted in a complete and persistent insulin depletion (basal serum immunoreactive insulin less than or equal to 3 microU/ml, no stimulated response) without toxic organ damage or other serious side effects. The dogs developed type I-like diabetes, which required continuous exogenous insulin substitution. From these results, subtotal pancreatectomy with selective streptozotocin perfusion of the remaining pancreas is proposed as a safe model of insulin deficiency in dogs, which should be further evaluated in experimental diabetology.