Computer simulation of the propagation process in excitation of the ventricles

Simulation by a digital computer of propagated excitation in the ventricular myocardium has been accomplished. Experience with the program in normal conduction and in one example of abnormal conduction, an extrasystole, is presented. Results of the simulation process were in harmony with observations in animal experiments. This justifies attempts to apply this scheme to the analysis of abnormal ventricular excitation caused by other disturbances.

A crucial role of the Purkinje network in determining the course of excitation spread was recognized in the simulated process of both normal beats and extrasystoles. New knowledge is expected from this scheme when applied to other types of abnormal excitation.

The possibility of combining the scheme with a method of reconstruction of QRS complexes by means of "transfer impedance" values was pointed out.

On the genesis of the absolute ventricular arrhythmia associated with atrial fibrillation

Genetic factors in the formation of the long R-R interval in ventricular arrhythmia associated with atrial fibrillation were investigated in the isolated rabbit heart which was perfused using Langendorff's technique. The trans-membrane action potentials recorded from a single cell within the A-V node or within its vicinity were analyzed, and contiguous bipolar-lead electrograms simultaneously recorded from the right atrium and ventricle. Atrial fibrillation was induced by the combined application of acetylcholine solution and electrical stimulation. Atrial excitation was mainly blocked in the right atrium and in the anterior half of the A-V node.

To clarify further the time-correlation between the right atrial electrogram and the A-V nodal responses, the pattern of atrio-ventricular conduction was studied by applying only the electrical stimulation at high frequency without acetylcholine. The conduction was mainly blocked in the same sites as in the above experiment and the pattern of the conduction block in Wenckebach rhythm was observed. The conduction block within the anterior half of the A-V node may be the most important factor in producing the long R-R interval in atrial fibrillation. It was shown that the pattern of the conduction block can be explained by the Wenckebach rhythm.

Isolation of Cx-Reactive Protein by Gel Filtration and Characterization by Electrophoresis and Immunodiffusion

A simple and mild procedure circumventing the use of pneumococcal Cx-polysaccharide for the isolation and purification of CxRP from rabbit acute phase serum has been described. This has been achieved by two passages through Sephadex G 200 of the crude CxRP obtained by precipitation with (NH4)2SO4. The purified CxRP characterized by electrophoresis and immunodiffusion appears to be a carbohydrate containing protein. Its relationship to CRP was shown by immunodiffusion with goat and horse CxRPA. It can be concluded that CxRP as it occurs in acute phase serum might be a complex entity.