Subnormalization of left ventricular shape after successful coronary revascularization.

BACKGROUND: It is asumed that the shape and size of the left ventricle could change after successful revascularization and that the shape and size reflect left ventricular function. METHODS: Echocardiography and Simpson's rule were used for evaluating the endocardial surface area of the left ventricle and elongation of the left ventricle as shape index in 13 patients before coronary arterio-venous bypass grafting (CABG) and 1 year after successful CABG. RESULTS: After successful CABG, the left ventricle becomes bigger and less elongated than before CABG. Results show a change from concentric hypertrophy of the left ventricle before CABG to subnormalization after CABG. DISCUSSION: We suppose that the subnormalization of left ventricular size and shape is the result of successful CABG and successful rehabilitation. The change of left ventricular size and shape after CABG might depend more on the original state of the left ventricle before surgery.

Virtual coronary cineangiography.

The mastering of myocardial infarction diagnosis is traditionally composed of laborious trial- and error-based examination of canonical coronary cineangiographies. In the following article we suggest a system that enables the instructor to generate student-specific cases, thus allowing teaching not only the basic feature searching and stenosis evaluation processes, but also the importance of the correct acquisition viewpoint. With the proposal of the development of the Digital Cardiologist intelligent agent we also envisage the possibility of the student's self-tutoring.

Visualization of computer simulated heart temperature during topical cooling.

A local hypothermia is often used during cardiac operations to slow down the tissue metabolism. The heart is cooled down with cold cardioplegic solution. Sometimes even the topical cooling with or without ice slush is used. Different heart models have been used earlier to simulate heart temperature distribution, but the resolution of the model has always been limited by the speed of the computer. We used the computer heart model derived from Visible Human Dataset with the spatial resolution of 1 mm. In this article, the step-by-step generation of 3D computer heart model is described. The heat transfer was modeled by a diffusion equation that was discretised in space and time and solved by a parallel algorithm. Finally, the cooling of heart during an operation, with and without topical ice slush, was simulated on a cluster of 9 PC-based computers, which assured sufficient computing power. The simulated results are presented as images of cross sections in different planes with temperatures shown by different colors.

Measurement of porcine heart temperatures.

During cardiac surgery local hypothermia of the heart is used to slow down cellular metabolism. It has been shown by computer simulation that heart muscle is not uniformly cooled to the desired temperatures. The aim of our work was to find out a way for measuring the temperatures of the ventricular wall and the septum with +/-0.1 degrees C accuracy. The measurement protocol should be applicable during operations on the human heart, during which disturbing factors should be minimized. We have tested the protocol and the equipment on porcine hearts. Two types of probes were tested, the contact-probe, which can be attached to the heart-wall surface, and the needle-probe, which can be inserted into the heart tissue. Before experiments the probes were calibrated and their heat transfer characteristics determined. We conclude that the probes and the protocol are suitable for studying the effects of cardioplegia, and for checking the results previously obtained by computer simulation.

[On the effect of iodine containing opaque media on erythrocyte acetylcholinesterase (author's transl)]. / Zur Wirkung von jodhaltigen Kontrastmitteln auf die Erythrozyten-Acetylcholinesterase.

Clinical symptoms of side effects by iodinated opaque media are approximately similar to those caused by inhibition of acetylcholinesterase. The inhibition of acetylcholinesterase of human erythrocytes was tested with the following opaque media in vivo and in vitro: adipiodonmeglumine, meglumine-iothalamate and sodium-iothalamate. Apparently there is no connection between opaque media induced incompatibility and the inhibition of acetylcholinesterase because 1. by the time maximal inhibition is reached most of the renally excreted opaque media has been eliminated, and because 2. a fairly rapid reversibility of the inhibition follows. For patients with congenital variants of acetylcholinesterase it could be of clinical consequence under succinyldicholinanaesthesia.

[The effect of tri-iodinated contrast media on acetylcholinesterase of human erythrocytes (author's transl)]. / Die Wirkung trijodierter Röntgenkontrastmittel auf die Erythrozyten-Acetylcholinesterase des Menschen

The side effects of water soluble iodinated contrast media often mimic the clinical picture of acetylcholine intoxication. This prompted us to determine the amount of inhibition of human acetylcholinesterase by the following contrast media in vivo and in vitro: methyl glucamineiodipamide (Biligrafin forte), methylglucamine iothalamate (Conray 60), sodium-iothalamate (Conray 80). In vivo no correlation could be found between clinically manifest adverse reaction and enzyme inhibition after contrast media application. The in vitro values for 50% inhibition of erythrocyte acetylcholinesterase are: methylglucamine-iodipamide: 0.036 M, methylglucamine-iothalamate: 0.158 M, sodium-iothalamate: 0.3 M. Since in vitro, the maximal inhibitory effect of a given dose of contrast media can only be registered after a time interval when most of the contrast media in vivo has already been excreted by the kidneys or extracted by the liver, it seems very improbable that the enzyme inhibition seen in vitro should have any consequence whatsoever under clinical conditions. The in vitro inhibition of acetylcholinesterase is quickly reversible, with nearly all the activity regained 15 min after the removal of the contrast media.