Biomedical subjects

H C Cohen

Publications and source records attributed to H C Cohen.

31 records · Page 2Linked to original sources

PubMed1976

Concealed intraventricular conduction in the His bundle electrogram.

Multiple areas of concealed intraventricular conduction are deduced on the basis of aftereffects observed in His bundle recordings. Electrocardiograms and His bundle recordings are presented from two patients with unstable bilateral bundle branch block, the instability of which depended on the interval at which ventricular depolarization was initiated by sinus or paced impulses. This circumstance allows postulation of 1) concealed transseptal retrograde penetration of the left bundle branch system; 2) concealed transseptal retrograde penetration of the right bundle branch system; 3) alternate beat Wenckebach phenomenon with two areas of block in the bundle branch system with concealed penetration of the proximal area; 4) concealed re-entry in the right bundle branch system during an H-V Wenckebach cycle with resetting of the sequence of 2:1 H-V block and return of the re-entry wave to the A-V node causing subsequent A-H block; 5) proximal 2:1 block and distal Wenckebach block producing only two consecutively blocked beats; and 6) infrahisian Wenckebach block with changes both in A-V conduction and QRS contour.

Aged↗

PubMed1976

Echocardiography in mechanical alternans. With a note on the findings in discordant alternans within the left ventricle.

We described the echocardiographic manifestations of mechanical alternation of left ventricular (LV) contraction during regular sinus rhythm. Chronic LV dilatation and failure existed in all our four cases. Alternation was observed with respect to the following echocardiographic variables: amplitude and rate of increase of amplitude of systolic excursions of the LV posterior wall and ventricular septum (VS); reciprocal changes in the duration of LV ejection and pre-ejection periods (on the aortic valve echo) such that the total duration of LV electromechanical systole remained constant; reciprocal changes in the duration of RV ejection and pre-ejection periods (on the pulmonic valve echo) such that the total duration of RV electromechanical systole remained constant; systolic anterior excursion of the aortic root as a whole; steepness of the mitral EF slope; septal and LV posterior wall diastolic position; and end-systolic LV diameter. In two patients, discordant alternans of the motion of the LV posterior wall and the VS was observed.

Adult↗

PubMed1975

Disorders of impulse conduction and impulse formation caused by hyperkalemia in man.

In eight patients we have demonstrated manifold types of impairment of impulse conduction produced by hyperkalemia. These abnormalities of impulse conduction occurred either simultaneously or in sequence, and were located in the atria, in the A-V junction, in the fascicular distribution of the ventricular conduction system, or in the free ventricular walls. In association with the abnormalities of conduction, abnormal impulse formation was also frequently observed as manifested by acceleration of normal pacemakers or the emergence of ectopic pacemakers. In one patient hyperkalemia produced alteration in sinus and A-V junctional impulse formation which overshadowed conduction disorders. In all of the eight cases the hyperkalemia was considered to be noniatrogenic. Hyperkalemia appears to potentiate subclinical conduction abnormalities, especially in the His-Purkinje system. However, the presence of pre-existent intraventricular conduction defects such as a bifascicular block does not exclude the possibility that the site of an A-V conduction delay during hyperkalemia can be in the A-V node, as demonstrated by His bundle recording in one instance after development of second-degree (type I) A-V block.

Adolescent↗

PubMed1975

Diagnosis of cardiac tamponade by echocardiography: changes in mitral valve motion and ventricular dimensions, with special reference to paradoxical pulse.

The echocardiographic findings in three patients who presented with pericardial effusion and cardiac tamponade are described. Cyclic respiratory changes affected the diastolic movement of the anterior mitral leaflet, viz., during inspiration its anterior excursion decreased in amplitude and the E-F slope diminished. This inspiratory alteration in mitral valve motion was accompanied by an increase in right ventricular dimensions and a reciprocal decrease in left ventricular dimensions. Pericardial paracentesis confirmed the presence of effusion and relieved cardiac tamponade in all the patients. Repeat echocardiography, performed in two of the patients immediately after the pericardial tap, showed that the E-F slope had become steeper and that phasic respiratory variations in the diastolic motion of the anterior mitral leaflet were no longer present. The compatibility of our observations with the theories which endeavor to explain the mechanism of the paradoxical pulse in pericardial effusion with cardiac tamponade is discussed. We suggest that the abnormalities in anterior mitral leaflet motion defined by echocardiography constitute a useful addition to the study of patients with suspected cardiac tamponade resulting from pericardial effusion.

Adult↗

PubMed1974