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Biomedical subjects

W J Gussenhoven

Publications and source records attributed to W J Gussenhoven.

At least 19 recordsLinked to original sources
PubMed1992

Intraoperative angiography and endovascular ultrasound imaging.

Endovascular ultrasound imaging is a new technique that can be used to monitor intraoperatively the effects of balloon angioplasty or to inspect the quality of vascular reconstruction, such as endarterectomy or bypass surgery. The technique is based on high frequency ultrasonic imaging (30-40 MHz) using a rotating single element transducer mounted in an 8F catheter tip, providing 360 degrees cross-sectional real time images. The clinical application is based on the high correlation between the ultrasonic images and the histological characteristics of the corresponding vessel wall tissue and lumen geometry, as has been established in previous in vitro studies. Endovascular ultrasound assessment of percutaneous angioplasty procedures or intraoperative vascular reconstruction has become an adjunct to angiographic and/or angioscopic monitoring.

Angiography↗
PubMed1991

Assessment of arterial disease and arterial reconstructions by intravascular ultrasound.

Clinical application of intravascular ultrasound to assess arterial atherosclerotic disease was introduced in humans after extensive in vitro and in vivo animal studies. Real-time images, obtained with a 30 MHz element mounted on a 5 F catheter, consistently confirmed angiographic images, up till now considered to be the gold standard. In addition to these data, ultrasonic cross-sectional imaging provided information on the composition of atheroselectic lesions and the size and shape of the lumen. Based on the experimentally derived criteria for tissue characterization, a better insight into arterial morphology could be obtained, allowing improved planning of interventional or reconstructional procedures. Moreover intravascular ultrasound has proved valuable as a post-interventional procedure to monitor and assess the quality of interventional results. The ultrasound images are clearly superior to angiographic studies, albeit the ultrasonic information is an adjunct to angiography and, as yet, not a substitute. We present our initial experience with intravascular ultrasound obtained in patients with substantial peripheral arterial disease.

Angioplasty, Balloon↗
PubMed1991

Imaging of post-mortem coronary arteries by 30 MHz intravascular ultrasound.

Intravascular ultrasound cross-sectional imaging of the atherosclerotic artery may be employed to guide plaque ablation by spark erosion, atherectomy, laser irradiation or other means. To assess whether in the coronary artery the echolucent zone of the three-layered ultrasound appearance of muscular arteries might be a reliable boundary to halt transluminal ablative angioplasty, epicardial coronary arteries were scanned under pressure over a distance of 4-8 cm at 1 mm intervals. A 5.2F catheter with a 30 MHz transducer rotating at 600 RPM was used. In 419 images from four post-mortem hearts, aged at death 22, 31, 56 and 82 years, the presence of a distinct echolucent zone was scored as percentage of the wall circumference. The median scores were 0%, 0%, 10% and 75%, respectively. In the three youngest hearts, the three-layered appearance was largely absent. In the 82 year old heart, in contrast, the three-layered appearance could generally be identified. Within subjects, the presence of an echolucent zone was variable in location. Qualitatively, neither abundant medial elastin tissue nor a reduced medial thickness could explain the absence of an echolucent zone when the ultrasound image was compared to the corresponding microscopic section. The results show that in the 82 year old heart, 30 MHz intravascular ultrasound discrimination of coronary wall layers would be adequate to guide transluminal plaque ablation. In the younger hearts, guided ablation would fail due to the limited presence of a distinct echolucent zone as an ultrasound landmark of the media. Whether the presence or absence of an echolucent zone is related to age remains to be determined.

Adult↗
PubMed1991

Validation of quantitative analysis of intravascular ultrasound images.

This study investigated the accuracy and reproducibility of a computer-aided method for quantification of intravascular ultrasound. The computer analysis system was developed on an IBM compatible PC/AT equipped with a framegrabber. The quantitative assessment of lumen area, lesion area and percent area obstruction was performed by tracing the boundaries of the free lumen and original lumen. Accuracy of the analysis system was tested in a phantom study. Echographic measurements of lumen and lesion area derived from 16 arterial specimens were compared with data obtained by histology. The differences in lesion area measurements between histology and ultrasound were minimal (mean +/- SD: -0.27 +/- 1.79 mm2, p greater than 0.05). Lumen area measurements from histology were significantly smaller than those with ultrasound due to mechanical deformation of histologic specimens (-5.38 +/- 5.09 mm2, p less than 0.05). For comparison with angiography, 18 ultrasound cross-sections were obtained in vivo from 8 healthy peripheral arteries. Luminal areas obtained by angiography were similar to those by ultrasound (-0.52 +/- 5.15 mm2, p greater than 0.05). Finally, intra- and interobserver variability of our quantitative method was evaluated in measurements of 100 in vivo ultrasound images. The results showed that variations in lumen area measurements were low (5%) whereas variations in lesion area and percent area obstruction were relatively high (13%, 10%, respectively). Results of this study indicate that our quantitative method provides accurate and reproducible measurements of lumen and lesion area. Thus, intravascular ultrasound can be used for clinical investigation, including assessment of vascular stenosis and evaluation of therapeutic intervention.

Angiography↗
PubMed1991

Backscatter directivity and integrated backscatter power of arterial tissue.

A 27 MHz transducer, mounted on an ultrasonic microscope, was used to quantify the dependence of backscatter power on the angle of incidence of arterial vessels. Due to variations in the angle of incidence significant variations in backscatter power were found in the intima, the muscular and elastic media, the adventitia and the external elastic lamina. The muscular and the elastic media show anisotropic behaviour in their angle dependence, i.e. the extent of the angle dependence depends on the direction of angle variation. This anisotropic nature is probably caused by the dominant orientation of smooth muscle cells or elastin fibers in these tissue layers. Measurements on 13 specimens of the iliac artery showed that each tissue type of the vessel has its own specific angle dependent behaviour. In the future this property might be used for quantitative tissue characterization.

Humans↗
PubMed1991

Cyclic changes of blood echogenicity in high-frequency ultrasound.

Ultrasound images from human arteries obtained in vivo with an intravascular 30 MHz ultrasound imaging device show that blood echogenicity changes during the cardiac cycle. Quantitative measurements of blood echogenicity during the cardiac cycle suggest that these variations may be related to changes in the state of erythrocyte aggregation, which are induced by varying shear rate.

Blood Flow Velocity↗
PubMed1991

Angle-dependent backscatter from the arterial wall.

The anisotropic nature of intra-arterial echographic images is reported, and the source of this anisotropy is investigated using postmortem human iliac arteries. A 27 MHz transducer, mounted on an ultrasonic microscope, is used to quantify the angular dependence of the backscatter power versus the angle of incidence, and these results are correlated with histological findings. Besides the observed differences in the acoustic response of morphologically different tissues, significant variations in backscatter power are found in both media and internal elastic lamina due to variations in the angle of incidence. This angle dependence is caused by the dominant orientation of fibers in tissue layers and by the shape and size various scattering particles. The results indicate that long microscopic structures with one main orientation are responsible for the backscattered signal and that the angular-dependent response is related to the histologically determined orientation of these fibers. These results may have an impact on the assessment of intra-arterial echographic images.

Blood Vessels↗
PubMed1990

Clinical perspectives of intravascular ultrasound.

The history of intravascular ultrasound imaging, recent developments in catheter technology, and the initial in vivo experience are reviewed. Additionally, the article also discusses the potential applications of intravascular ultrasound imaging in coronary and peripheral arterial atherosclerosis, hypertension, pulmonary arterial disorders, valvular heart disease, aortic abnormalities, and in congenital heart disorders. Possible future directions are outlined.

Coronary Artery Bypass↗
PubMed1989

Early and recent intraluminal ultrasound devices.

The history of intraluminal echography dates back to the very beginning of diagnostic ultrasound. Over the years many fascinating ideas and applications of catheter tip or gastroscopic tube tip mounted transducers have been described. This chapter surveys these methods, subdividing them into a) measurements; b) Doppler and c) imaging. The survey ranges from early work of Cieszynski on the feasibility of echocardiography to more recent intra-arterial catheter tip Doppler with guidewire and balloon as described by Serruys. Examples of ultrasound catheter tip echography in combination with other techniques such as angioscopy, laser ablation and spark erosion are also described. Today practical approaches are limited to imaging only. The three major approaches for catheter tip echo imaging are described and compared. This paper concludes with the results of automatic contour analysis of the inner arterial boundaries.

Cardiac Catheterization↗
PubMed1989

Intravascular echographic assessment of vessel wall characteristics: a correlation with histology.

In vivo application of intravascular high frequency ultrasonic imaging for peripheral and coronary artery disease is a promising technique for vascular surgeons, radiologists and cardiologists. This report demonstrates in vitro results obtained with a high frequency imaging catheter (40 MHz) in 70 human specimens including arteries with and without atherosclerosis, veins, coronary artery bypass grafts and vascular prosthetic material. Correlation between the ultrasonic images and the histologic characteristics of the corresponding vessel wall tissue and lumen geometry was established. In addition, the effect of intervention techniques i.e. balloon angioplasty, spark erosion and laser were studied with ultrasound and histology. It is anticipated that development of such a catheter imaging technique has potential for diagnostic imaging and for combination with therapeutic systems.

Angioplasty, Balloon↗
PubMed1988

The role of intraoperative two-dimensional echocardiography in the assessment of thoracic aorta pathology.

The role of intraoperative two-dimensional echocardiography is discussed in 15 consecutive patients with thoracic aorta pathology undergoing cardiac surgery. A 5 MHz mechanical scanner was used before and immediately after cardiopulmonary bypass. In 5 patients intraoperative two-dimensional studies revealed crucial morphologic information which, consequently, had a marked influence on their planned surgical procedure. In 3 patients the findings provided additional information whereas in the remaining patients the intraoperative echocardiographic findings confirmed the preoperative diagnosis. Following surgery the adequacy of cardiac repair was assessed and, in one patient, epicardial echocardiography indicated the necessity for reoperation. The application of intraoperative two-dimensional echocardiography leads to a better understanding of the pathology involved and facilitates a more appropriate decision concerning the surgical procedure.

Adolescent↗
PubMed1988

The value of transoesophageal echocardiography for diagnosis of thoracic aorta pathology.

The potential of transoesophageal echocardiography for preoperative diagnosis of thoracic aorta pathology was evaluated in 15 patients with aortic dissection and 15 patients with aortic aneurysm. The transoesophageal echocardiographic findings were compared with 14 computed tomograms and 21 angiograms. Six patients underwent only transoesophageal echocardiography. All patients were operated upon and the surgical findings were used as a reference for these diagnostic methods. Transoesophageal echocardiography established a complete and correct diagnosis in 27 patients. The diagnosis was partially correct in three patients, all having an aortic dissection. A complete and correct diagnosis was obtained by computed tomography and angiography in 8 and 17 patients, respectively. The results indicated that transoesophageal echocardiography is a sensitive and convenient method for the definitive diagnosis of pathology of the thoracic aorta. It could become the technique of choice in patients suspected of having acute aorta pathology as it enables a rapid and definitive diagnosis at the bedside.

Adult↗
PubMed1988

Saccular aneurysm of the transverse thoracic aorta detected by transesophageal echocardiography.

A patient with a saccular aneurysm of the thoracic aortic arch presented with severe right ventricular failure due to pulmonary artery compression. Contradictory data were derived from computed tomography, pulmonary isotope perfusion scan and cardiac catheterization. Transesophageal echocardiography revealed a saccular aneurysm which compressed the main pulmonary artery and gave access to a fistulous connection to the left pulmonary artery. Surgery confirmed these findings.

Aorta, Thoracic↗
PubMed1986

Growth and function of the right ventricular outflow tract after Fontan's procedure for tricuspid atresia: a two-dimensional echocardiographic study.

Two patients with classical tricuspid valve atresia were studied by two-dimensional echocardiography before and up to 6 years after Fontan's correction. Preoperative investigation revealed a diminutive right ventricular outflow chamber, which increased in size postoperatively and became functional. These data were compared to those obtained in normal individuals.

Adolescent↗
PubMed1986

Intraoperative epicardial two-dimensional echocardiography.

The usefulness of intraoperative epicardial two-dimensional (2D) echocardiography using a commercially available 5 MHz mechanical sector scanner was evaluated in 200 patients. The scanhead was inserted into a gas sterilized plastic bag and placed on the exposed heart. Unsuspected new diagnoses were made in 7 patients. In 68 patients additional morphologic information was obtained. This information influenced surgical management in 32 patients. Intraoperative echocardiographic analysis of the surgical correction revealed the expected results in 184 patients. In 16 patients the investigation provided important information in the decision of immediate reoperation. We conclude that epicardial two-dimensional echocardiography performed by the surgeon familiar with the interpretation of echocardiographic cross-sections yields important information for surgical management. The technique has become an important adjunct in our cardiac surgery department for immediate decision making and leads to optimal results.

Adolescent↗
PubMed1984

Variability in the time interval between tricuspid and mitral valve closure in Ebstein's anomaly.

The time interval between mitral and tricuspid valve closure was measured from M-mode echocardiograms in patients with Ebstein's anomaly. It was found that this time interval demonstrated a range of values within each patient. The use of different transducer positions on the chest wall was found to be the predominant factor. There was no correlation between the measured time interval, its variability, and the moment of measurement during breathing. However, a period of breathholding significantly reduced the variability. This study indicates that a wide range of time intervals might be measured in a single patient. We conclude therefore, that this parameter should be used with great care in the diagnosis of Ebstein's anomaly.

Ebstein Anomaly↗