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Biomedical subjects

N D Berman

Publications and source records attributed to N D Berman.

46 records · Page 3Linked to original sources
PubMed1976

Angiographic demonstration of blood supply of right atrial myxoma.

A 53-year-old woman underwent cardiac catheterization for assessment of coronary arterial disease. An unexpected finding of a gradient between right atrium and right ventricle led to the discovery of an unsuspected right atrial myxoma. The diagnosis was established by the presence of a filling defect in the right atrial angiocardiogram and by the demonstration of "tumour vessels" by selective right coronary angiography. Selective coronary angiography can visualize the blood supply to an intracardiac tumour and thus confirm the diagnosis preoperatively.

Coronary Angiography↗
PubMed1975

Mitral stenosis with posterior diastolic movement of posterior leaflet.

The echocardiographic diagnosis of mitral stenosis depends in part on the demonstration of abnormal posterior leaflet movement to distinguish it from other conditions that similarly affect anterior leaflet motion. In mitral stenosis the posterior leaflet has been shown to move anteriorly in diastole rather than in the normal posterior direction. A patient presented with clinical evidence of moderate mitral stenosis. The anterior leaflet echo was typical but the posterior leaflet showed posterior diastolic movement. At catheterization moderate mitral stenosis was confirmed. To our knowledge this is the first report of the echocardiographic demonstration of posterior diastolic movement of the posterior mitral leaflet in documented mitral stenosis.

Angiocardiography↗
PubMed1975

Saphenous vein bypass grafting. Changes in native circulation and collaterals.

One hundred patients were evaluated 12 to 43 months after saphenous vein bypass surgery. The rate of progression of obstructive disease in the native vessels and changes in collateral circulation were analyzed in detail. Fifty-five per cent of preoperatively patent vessels showed progression proximal to the site of graft insertion, 40% proximal to patent grafts; there was distal progression in only 7% of grafted vessels. The progression rate for nongrafted vessels was 14%. Patent grafts were associated with a high rate of disappearance of collaterals to the grafted vessels, while occluded grafts were associated with preservation of collaterals or appearance of new collaterals. Progression of obstructive disease in the native circulation and changes in collaterals did not prevent symptomatic improvement (93% of patients were symptomatically improved).

Adult↗
PubMedDate not supplied

A simple BASIC program for constructing three-dimensional graphs.

This report describes a simple program for plotting three-dimensional curves and thus allowing a visual representation of the simultaneous interaction of three variables. Graphs can be displayed on the screen or printed using a graphics printer. The original data can be stored, printed, recalled and edited, as can the graph parameters. Completed graphs can also be stored for later review or printing. The program as outlined can accommodate up to 10 curves of up to 50 points each, but these limits can be easily increased. The program is written in BASIC, thus allowing it to be readily modified. As listed, the complete source code has 357 lines and occupies about 12 kilobytes when saved in compressed binary format.

Computer Graphics↗
PubMedDate not supplied

Differential electrophysiologic effects of mexiletine on normal and hypoxic canine Purkinje fibers.

We studied the effects of increasing concentrations of mexiletine on the active membrane characteristics of canine Purkinje fibers under normal and hypoxic conditions. Under normal conditions, there was a progressive shortening of action potential duration and a small decrease in maximum diastolic potential and overshoot potential. Effective refractory period was shortened by low concentrations but lengthened by higher concentrations. Only at the higher concentrations was Vmax decreased. When the tissue was rendered hypoxic, the shortening effect on action potential duration was attenuated. Low concentrations of mexiletine had a more pronounced effect on maximum diastolic potential and overshoot potential. The reversal of the effect on refractory period occurred at lower concentrations. The effect on Vmax was exaggerated. Hypoxia sensitizes Purkinje fibers to some of the electrophysiologic effects of mexiletine, but other effects are, in fact, attenuated in the presence of hypoxia.

Action Potentials↗
PubMedDate not supplied

Effects of simultaneous administration of mexiletine and quinidine on the electrophysiologic parameters of canine Purkinje fibers.

The electropharmacologic effects of an equimolar combination of mexiletine and quinidine on canine Purkinje action potential parameters were compared with the effects of either drug alone in concentrations ranging from 0.31 to 5.0 X 10(-5) M. Six separate experiments were performed with mexiletine alone, quinidine alone, and the combination. At low concentrations, all three shortened action potential duration (APD) and effective refractory period (ERP) to the same degree; however, the combination depressed Vmax to the same extent as did solutions containing twice the concentration of quinidine alone even though mexiletine alone, in these concentrations, had no effect on the maximum rate of depolarization of phase 0 of the action potential Vmax. In higher concentrations, the combination depressed Vmax and prolonged the ERP to values midway between that achieved by the two drugs separately. Although increasing concentrations of mexiletine alone progressively shortened APD, the combination prolonged this parameter to values similar to those seen with twice the concentration of quinidine alone. The electropharmacologic effects of mexiletine and quinidine in combination are not simply additive and cannot be entirely predicted on the basis of a knowledge of their effects in isolation.

Action Potentials↗
PubMedDate not supplied

The cellular electropharmacology of mexiletine in papillary muscles of guinea pigs chronically treated with amiodarone.

OBJECTIVE: The combination of mexiletine and amiodarone has proved useful in the control of serious ventricular arrhythmias, but the electrophysiological basis for their effectiveness in combination is unknown. The objective of this study was to compare the effects of mexiletine on action potential parameters of papillary muscles taken from guinea pigs chronically treated with amiodarone, with tissue taken from a control group. DESIGN: The effects of 12.5 to 200 microM mexiletine on action potential parameters of papillary muscles taken from guinea pigs chronically treated with amiodarone were compared with tissue taken from a control group, at frequencies of 1.0, 1.5 and 3.0 Hz, using standard microelectrode techniques. Onset of use-dependent block was assessed by 30 beat trains, and recovery from block by extrastimuli at diastolic intervals ranging from 200 to 5000 ms at both 1.5 and 3.0 Hz. ANIMALS: Eighteen four-week-old guinea pigs were randomly divided into two groups. One group received amiodarone in a loading dose of 20 mg/kg/day by intraperitoneal injection for one week, followed by 10 mg/kg/day for 15 weeks. The control animals were given equivalent volumes of dextrose intraperitoneally for 16 weeks. MAIN RESULTS: Mexiletine depressed the maximum rate of depolarization of phase 0 of the action potential (Vmax) in a concentration- and use-dependent fashion. Whereas chronic amiodarone treatment did not alter steady-state Vmax values, the extent of tonic Vmax depression induced by mexiletine was decreased, while use-dependent depression was increased. Mexiletine combined with amiodarone increased effective refractory period prolongation from 306.7 +/- 27.2 to 348.8 +/- 37.2 ms, while action potential duration shortening of mexiletine was moderated from 134.0 +/- 19.8 to 151.0 +/- 8.3 ms (to 90% repolarization at 3 Hz in the presence of 200 microM mexiletine).

Action Potentials↗