Catharina E. Essed

Vaporization of atherosclerotic plaques by spark erosion

An alternative to the laser irradiation of atherosclerotic lesions has been developed. A pulsed electrocardiogram R wave-triggered electrical spark erosion technique is described. Controlled vaporization of fibrous and lipid plaques with minimal thermal side effects was achieved and documented histologically in vitro from 30 atherosclerotic segments of six human aortic autopsy specimens. Craters with a constant area and a depth that varied according to the duration of application were produced. The method was confirmed to be electrically safe during preliminary in vivo trials in the coronary arteries of seven anesthetized pigs. The main advantages of this technique are that it is simpler to execute than laser irradiation and potentially more controllable.

TRANSMISSION OF ULTRASONIC CONTRAST THROUGH THE LUNGS

The pulmonary capillary bed normally removes echocardiographic contrast from the circulation, so contrast injected peripherally or on the right side of the heart is not seen on the left side of the heart in the absence of intracardiac or intrapulmonary shunts. Based on recent advances in the theoretic understanding of microbubble physiology, we propose several theoretic methods for causing the transmission of ultrasonic contrast through the lungs to enable opacification of the left side of the heart. Three of these methods are tested: (I) injection of ether, an organic compound which may pass the pulmonary capillaries in the liquid phase and cavitate in the pulmonary veins to yield left heart echo contrast, (2) injection of hydrogen peroxide, a substance which chemically decomposes on the left side of the heart to yield gaseous oxygen that can be imaged as echo contrast, and (3) injections of 5% dextrose in the pulmonary wedge position. The first two methods were tested in anesthetized pigs, and the third method in humans and anesthetized rabbits. All methods could cause transmission of echocardiographic contrast through the lungs. There were no adverse reactions in the human subjects. Pulmonary wedge injections in rabbits were associated with one large and three small myocardial infarctions out of 7 animals sacrificed 24 hr later. We conclude that transmission of echocardiographic contrast through a capillary bed is feasible though potentially dangerous.

Right to left shunt, with severe hypoxemia, at the atrial level in a patient with hemodynamically important right ventricular infarction

This report describes a patient with a massive right ventricular infarction, complicated by severe hypoxemia. Contrast echocardiography demonstrated a right to left shunt through a previously asymptomatic atrial septal defect. This phenomenon should be considered as a possible cause of hypoxemia in the presence of right ventricular infarction.

Offsetting of the septal tricuspid leaflet in normal hearts and in hearts with Ebstein's anomaly: anatomic and echographic correlation

Apical displacement of the septal tricuspid valve leaflet is considered the most reliable criterion to diagnose Ebsteins anomaly. This feature is best assessed using 2-dimensional echocardiography. However, the anatomy in Ebsteins anomaly is highly variable; therefore, the problem arises as to how to distinguish between the abnormal displacement in borderline cases of Ebsteins disease and the lowered septal offsetting of the tricuspid valve in normal persons. To solve this problem the minimal and maximal differences in offsetting of the tricuspid and mitral valves have been studied, both anatomically and echocardiographically, in fetuses, infants, children and adults. In fetuses in the first trimester of pregnancy it was impossible to measure a difference in offsetting of the 2 atrioventricular valves. Thereafter, a gradual increase occurred with age. In normal hearts the most significant separation was usually recorded in anteriorly angulated 4-chamber views, whereas in hearts with Ebsteins anomaly maximal separation appeared to posteriorly angulated views. The anatomic and echographic measurements showed a constant relation. When the minimal distances in offsetting were measured, an overlap was found between cases with and those without Ebsteins anomaly. The maximal values, however, clearly discriminated between the 2 conditions. The critical difference in children was 15 mm, and in adults the discriminating value was 20 mm.

Unguarded tricuspid orifice with two-chambered right ventricle.

SummaryCatheterization and anatomical data are presented of an infant with cyanosis due to a most unusual variant of unguarded tricuspid valve orifice in association with a two-chambered right ventricle. The inlet portion of the right ventricle ended blindly and was completely separated from the outlet portion by a muscular wall. The outlet chamber, which supported the pulmonary trunk, received its blood from the left ventricle through an outlet foramen. The condition is considered to be related to imperforate Ebsteins anomaly.

Restenosis 3 months after successful percutaneous aortic valvoplasty. A clinicopathological report

A 76-year-old man with severe, calcific aortic stenosis experienced recurrence of symptoms 3 months after a successful percutaneous aortic valvoplasty. Echo Doppler revealed a marked increase of peak aortic flow velocity as compared with the immediate post-valvoplasty value. The patient underwent an uncomplicated aortic valve replacement. Adjacent to fragmented calcification, histology demonstrated a scarring reaction which might well be a major factor in the restenosis process.

Three-dimensional reconstruction of myocardial contrast perfusion from biplane cineangiograms by means of linear programming techniques.

SummaryThe assessment of coronary flow reserve from the instantaneous distribution of the contrast agent within the coronary vessels and myocardial muscle at the control state and at maximal flow has been limited by the superimposition of myocardial regions of interest in the two-dimensional images. To overcome these limitations, we are in the process of developing a three-dimensional (3D) reconstruction technique to compute the contrast distribution in cross sections of the myocardial muscle from two orthogonal cineangiograms. To limit the number of feasible solutions in the 3D-reconstruction space, the 3D-geometry of the endo- and epicardial boundaries of the myocardium must be determined. For the geometric reconstruction of the epicardium, the centerlines of the left coronary arterial tree are manually or automatically traced in the biplane views. Next, the bifurcations are detected automatically and matched in these two views, allowing a 3D-representation of the coronary tree. Finally, the circumference of the left ventricular myocardium in a selected cross section can be computed from the intersection points of this cross section with the 3D coronary tree using B-splines. For the geometric reconstruction of the left ventricular cavity, we envision to apply the elliptical approximation technique using the LV boundaries defined in the two orthogonal views, or by applying more complex 3D-reconstruction techniques including densitometry. The actual 3D-reconstruction of the contrast distribution in the myocardium is based on a linear programming technique (Transportation model) using cost coefficient matrices. Such a cost coefficient matrix must contain a maximum amount of a priori information, provided by a computer generated model and updated with actual data from the angiographic views. We have only begun to solve this complex problem. However, based on our first experimental results we expect that the linear programming approach with advanced cost coefficient matrices and computed model will lead to acceptable solutions in the 3D-reconstruction of the myocardial contrast distribution from biplane cineangiograms.

Three-Dimensional Reconstruction of Myocardial Contrast Perfusion from Biplane Cineangiograms

The assessment of coronary flow reserve from the instantaneous distribution of the contrast agent within the coronary vessels and myocardial muscle at the control state and at maximal flow has been limited by the superposition of myocardial regions of interest in the two-dimensional images. To overcome these limitations, we are in the process of developing a three-dimensional (3D) reconstruction technique to compute the contrast distribution in cross sections of the myocardial muscle from two orthogonal cineangiograms. To limit the number of feasible solutions in the 3D- reconstruction space, the 3D-geometry of the endo- and epicardial boundaries of the myocardium must be determined. For the geometric reconstruction of the epicar-dium, the centerlines of the left coronary arterial tree are manually or automatically traced in the biplane views. Next, the bifurcations are detected automatically and matched in these two views, allowing a 3D-representation of the coronary tree. Finally, the circumference of the left ventricular myocardium in a selected cross section can be computed from the intersection points of this cross section with the 3D coronary tree using B-splines. For the geometric reconstruction of the left ventricular cavity, we envision to apply the elliptical approximation technique using the LV boundaries defined in the two orthogonal views, or by applying more complex 3D-reconstruction techniques including densitometry. The actual 3D-reconstruction of the contrast distribution in the myocardium is based on a linear programming technique (Transportation model) using cost coefficient matrices. Such a cost coefficient matrix must contain a maximum amount of a priori information, provided by a computer generated model and updated with actual data from the angiographic views. We have only begun to solve this complex problem. However, based on our first experimental results we expect that the linear programming approach with advanced cost coefficient matrices and computed model will lead to acceptable solutions in the 3D-reconstruction of the myocardial contrast distribution from biplane cineangiograms.