Early experiences with the portable automatic external defibrillator in the home and public places.
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Biomedical subjects
Publications and source records attributed to K D Chadda.
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A post hospital follow-up system based on predetermined antiarrhythmic strategies and telephone transmitters used to record ECGs was helpful in managing post hospital course and improved survival in patients with a history of out-of-hospital sudden death. All patients underwent therapy guided by serial electrophysiologic testing. Of the 47 patients, 19 used the telephone transmitter system and 28 did not. During follow-up, residual symptomatic and silent ventricular arrhythmia was documented in 78% of patients using telephone transmitters. Ventricular tachycardia was transmitted in six patients--all survived. During an average 15-month follow-up, 1 of 19 patients using the telephone transmitter system died vs 12 deaths among the 28 patients who did not use the system (p less than 0.005). These results were independent of ejection fraction, presence of congestive heart failure, amiodarone therapy, and the outcome on electrophysiologic therapy. Thus, patients with a history of out-of-hospital sudden death, discharged following electrophysiologic guided therapy, require repeated antiarrhythmic dose titration for side effects or residual ventricular arrhythmia. Prompt diagnosis and treatment of potentially fatal arrhythmia is crucial and feasible, especially with regular ECG checks through telephone transmission.
Serum, whole blood and red blood (intracellular) magnesium determinations were made in 52 patients, without other factors predisposing to hypomagnesemia, admitted to a coronary care unit. Acute uncomplicated myocardial infarction was documented in 31 and the serum cardiac enzymes as well as the electrocardiogram remained nondiagnostic in 21 patients. There was no significant difference in the serum magnesium level in the two groups. An increasing trend with time was noted in the serum (p less than 0.001) and whole blood magnesium (p less than 0.005) during the first 4 days postmyocardial infarction. The whole blood magnesium as well as the red blood (intracellular) magnesium was higher (p less than 0.01) in myocardial infarction patients. There was no significant difference in the hematocrit or other electrolytes during this time.
The case report demonstrates another case of hypomagnesemia with electrocardiographic evidence of acute myocardial ischemia due to coronary spasm. The patient was successfully treated with intravenous, followed by oral, magnesium sulfate. Magnesium therapy may be justified especially in patients with prolonged QT intervals, cardiac arrhythmias and hypokalemia with hypomagnesemia.
Since there is very little available systematic information on the psychological profile of patients with cardiac arrhythmia, a battery of 12 standardized personality inventories was administered to 102 patients ranging in age from 19 to 69 years. Thirty-eight patients with frequent ventricular premature beats (more than 30 per hour) without myocardial infarction were significantly more psychologically symptomatic than 34 age- and sex-matched general medical/surgical patients. The variables found to be significant portray the patient with frequent ventricular premature beats without myocardial infarction: high scores for hysteria, less moral orientation, more anxiety, depression and social alienation, and an inhibited and low respectful style. This combination of psychological variables produced a discriminant function (p less than 0.001) that accounted for 53 percent of the variance between the arrhythmia/no myocardial infarction group and the medical/surgical control group and could correctly predict group membership in 83.3 percent of cases. These results may have further implications in nonpharmacologic and psychotropic adjuncts to antiarrhythmic therapy.
To evaluate changes in magnesium levels with treadmill exercise-induced coronary insufficiency, 59 consecutive patients were studied. In addition to electrocardiographic monitoring, hematocrit, total protein, whole blood, serum and red blood cell magnesium determinations were made before and after exercise testing. Fifteen patients had positive exercise test, 18 did not complete, and 26 had negative exercise test. There was no significant difference in the serum and red blood cell magnesium on the basis of stress test results for ischemia. Although whole blood magnesium, hematocrit, and total proteins increased (P less than .05) in both groups, we did not find a significant change in magnesium homeostasis.
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His bundle electrocardiography was performed on a patient with accidental hypothermia on whom the standard electrocardiogram (ECG) showed absent P waves, prominent J waves and a slightly irregular rhythm. Sino-ventricular conduction and a prolonged AH interval not responsive to atropine were found. These abnormalities reversed with rewarming.
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The auscultatory features typical of myxoma were absent in a patient with nonprolapsing left atrial myxoma. Angiocardiographic and echocardiographic findings including B-mode cross-sectional scanning are presented.
The case presented had an electrocardiographic pattern of complete right bundle branch block with alternating periods of left anterior hemiblock and left posterior hemiblock. During one of the periods of alternating hemiblock, an His bundle electrogram was recorded and the His Purkinje (H-V interval) conduction time was within normal limits. In a second episode of alternating hemoblock, periods of Mobitz type II second-degree A-V block were noted. It is postulated that this case provides clinical evidence that incomplete block of a fascicle may occur in spite of an electrocardiographic pattern of complete fascicular block. It is thought that the periods of alternating hemiblock result from a changing relationship between conduction velocity and refractory period.
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The presence of nocturnal angina and congestive heart failure within the month prior to admission was evaluated in the 174 patients with acute myocardial infarction. Heart size was evaluated radiographically at the time of admission. Twenty-three patients (13 per cent) experienced nocturnal angina. The incidence of nocturnal angina was significantly higher in those with anterior myocardial infarction (p less than 0.005) and subendocardial infarction (p less than 0.02) when compared with patients with inferior MI. Congestive heart failure was more common prior to admission in those with nocturnal angina (9/23) as opposed to those without (3/141) (p less than 0.001). Cardiomegaly was seen in 9/23 patients with nocturnal angina and 22/141 without (p less than 0.02). We conclude that the presence of nocturnal angina in those who develop MI increases the likelihood that the infarction will be either anterior or subendocardial rather than inferior. The association of nocturnal angina and congestive heart failure to anterior myocardial infarction is probably due to more severe and probably significant left coronary artery disease.
Thirty-eight patients with right bundle branch block and left anterior hemiblock who had undergone His bundle recordings were prospectively followed for development of heart block. Twenty-five were male and thirteen female. Their ages ranged from 35 to 92 with an average age of 74 years. The mean follow-up period was 28.5 months (range 2-52 months). The H-V interval was 55 msec or less in 17 patients (Group A), between 56 and 75 msec in 13 (Group B), and more than 75 msec in eight (Group C). Ten patients (26%) died during the follow-up period. Of these, three were in Group A (mortality rate 8% per year), three in Group B 10% per year), and four in Group C (21% per year). None of the deaths in Groups A and B were sudden, while one possible sudden death occurred in Group C. Mode of death in one patient each from Groups B and C remained unknown. Heart block was not seen in any patient from Group A and B, while two patients from Group C progressed to complete heart block during the follow-up period. It is concluded that patients with right bundle branch block and left anterior hemiblock with prolonged H-V intervals tend to show a higher mortality when compared to those with normal H-V intervals. A definite risk of heart block exists in patients with H-V intervals of more than 75 msec.
This report describes 16 patients with block within the His bundle seen over a period of 55 months. Ten were women and 6 men, with an average age of 76 years, range, 42 to 98 years. All patients had His bundle recordings showing split His bundle potentials (H and H) (13 patients) or narrow QRS with block distal to the His bundle potential (3 patients). Of the 16 patients, 10 had complete heart block, 4 second degree AV block (2 patients with Mobitz type II, and 2 with 2:1), and 2 first degree AV block. Ten patients had a narrow QRS in the conducted beats or escape rhythms. Intravenous atropine (1 to 2 mg) had a variable effect on AV conduction and the rate of the escape rhythm. Twelve patients have had a permanent pacemaker implanted. During the follow-up period, 10 patients died 1 to 31 months from the time of initial examination. The remaining 6 patients (5 with pacemaker) are alive 3 to 58 months later.
The hospital course and serial vectorcardiograms of 56 consecutive patients with acute inferior wall myocardial infarction were reviewed. Left anterior hemiblock (LAH) complicating inferior wall myocardial infarction was diagnosed by vectorcardiographic criteria. Seven patients (12.5%) developed LAH between the first and third hospital day, while 49 patients did not. There was no significant difference between these two groups when compared for age, sex, incidence of congestive heart failure, atrial and ventricular arrhythmias, atrioventricular (A-V) block, hospital mortality, and previous hypertension, diabetes mellitus, and myocardial infarction. We conclude that LAH is a relatively common complication of acute inferior wall myocardial infarction, with no apparent effect on the clinical course.