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Biomedical subjects

M Kleinfeld

Publications and source records attributed to M Kleinfeld.

At least 37 records · Page 2Linked to original sources
PubMed1984

Pacemaker alternans.

A 52-year-old man was implanted with a Gemini pacemaker for complete heart block which developed suddenly three months after coronary reconstruction and endocardial resection to treat chronic recurrent ventricular tachycardia. Pacemaker alternans, which is a rare phenomenon, occurred two days after pacemaker implantation and then disappeared 24 hours later. The patient was followed for a two-month period during which the pacemaker system functioned normally. Many of the possible mechanisms which may produce pacemaker alternans were explored. Our findings are presented in this report.

Arrhythmias, Cardiac↗
PubMed1982

Alternans of the ST segment of T wave. A sign of electrical instability in Prinzmetal's angina.

In an effort to determine the incidence of ventricular arrhythmias associated with ST segments alternans, the patterns of ST segment and T-wave electrical alternans (STEA) were analyzed in 93 patients during spontaneous Prinzmetal's angina. Twenty-eight of 93 patients, or 30% (Group I), showed STEA during episodes of ST segment elevation. SIxty-five of 93 patients, or 70% (Group II), showed no alternans during episodes of ST segment elevation. In Group I, ventricular arrhythmias, defined as all ventricular ectopic activity greater than 5 beats per minute and complex Lown grades III to V, occurred during 52 of 55 episodes, or 95%; whereas in Group II, ventricular arrhythmias occurred in only 51 of 125 episodes, or 41% (p less than 0.01). The difference in the incidence of ventricular fibrillation (VF) or ventricular tachycardia (VT) in the two groups was more striking. VT or VF occurred in 20 of 55 in Group I (36%) versus 5 of 125 in Group II (4%). Although there were no significant differences in age or sex between Group I and II patients, there was a significant difference in the magnitude of the maximum ST segment elevation (5 mm in Group I versus 3 mm in Group II, p less than 0.01). This study demonstrates that the occurrence of STEA and T wave alternans frequently heralds the onset of ventricular arrhythmias in Prinzmetal's angina. Both the arrhythmias and the alternans occur during the time of maximal ST segment elevation.

Angina Pectoris, Variant↗
PubMed1981

The mechanism of flutter electrical alternans.

We have had the opportunity to observe the occurrence of flutter electrical alternans in which two distinct populations of flutter waves are present and which alternate in 1:1 and 2:1 patterns. The flutter alternans whether 2: or 3:1, was concordant with the pattern of preceding ventricular conduction (ventriculophasic variation). This concordance occurred reproducibly and remained consistent. Our example of flutter alternans probably represents mechanical artefact caused by catheter movement during ventricular mechanical systole. We reproduced this pattern consistently at a slower rate during coronary sinus pacing. These findings appear to suggest an explanation for certain types of so-called atrial flutter electrical alternans.

Atrial Flutter↗
PubMed1980

TQ segment (baseline) alternans during Prinzmetal's variant angina.

In a study of 93 patients who met criteria for Prinzmetal's angina, alternans of the ST segment was observed in 28 of 93 patients (30%). In 8 of these 28 patients, a hitherto undescribed variant of alternans, namely alternation (larger than or equal to 1 mm shift in 2:1 pattern) in the amplitude of the baseline or TQ segment (TQ Alt) was observed. In all eight patients serious ventricular arrhythmias were noted, namely, ventricular fibrillation in two, ventricular tachycardia in four, and multiform or advanced ventricular ectopic activity in eight. The TQ Alt developed only after ST segment alternans occurred. It is postulated that the alternations of the ST and TQ segments are due to differences in current flows due to inhomogeneity of depolarization and repolarization of the action potential caused by ischemia. Furthermore, the associated arrhythmias observed are related to the inhomogeneous state initiated by the ischemia.

Action Potentials↗
PubMed1976

Cardiac motion in total electrical alternans.

Gross pendular motion of the heart at half the heart rate was observed during cardiac catheterization and pericardiotomy in a patient with massive pericardial effusion and electrical alternans in the electrocardiogram. These observations support the hypothesis that total electrical alternans in pericardial effusion is a result of alternate change in cardiac position.

Adult↗
PubMed1976

Situs inversus, subaortic and subpulmonic stenosis, ventricular septal defect, and single coronary artery.

The unusual occurrence of situs inversus totalis, ventricular septal defect, hypertrophic subaortic and subpulmonic stenosis, and single coronary artery in a 38-year-old man is presented. The clinical course was remarkably mild, as documented by data from 23 years of study including four cardiac catheterizations. At age 35 years, however, syncope, chest pain, and marked elevation of right ventricular pressure prompted complete surgical repair of the left and right ventricular outflow tract obstructions and closure of the septal defect. Three years after surgery the patient continues to lead an active life without symptoms. The unusually mild course can be attributed to the natural banding effects of the subpulmonic stenosis which prevented irreversible pulmonary hypertension.

Adolescent↗
PubMed1975

Complication of prolonged intestinal intubation: gaseous distention of the terminal balloon.

A patient with regional enteritis was treated with a Cantor tube for relief of intestinal obstruction. Gaseous distention of the terminal balloon of the tube occurred necessitating removal by laparotomy and enterostomy. This rare complication is reviewed and discussed with special reference to etiology and prevention. The relationship of this complication to prolonged intubation is emphasized.

Adult↗