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Biomedical subjects

E K Chung

Publications and source records attributed to E K Chung.

At least 37 records · Page 2Linked to original sources
PubMed1980

Clinical value of ambulatory rhythm monitoring.

(1) Ambulatory (Holter monitor) electrocardiography is currently one of the most important noninvasive cardiac diagnostic tests in our daily practice. (2) The primary purpose of Holter monitor electrocardiography is to diagnose various cardiac arrhythmias with accuracy, especially when the routine 12-lead electrocardiogram fails to record the arrhythmia because of its transient and episodic nature. (3) A precise etiology of a dizzy spell or a fainting episode can be confirmed by the Holter monitor ECG, when various symptoms are directly related to either tachyarrhythmias or bradyarrhythmias. (4) Another very important role of the Holter monitor ECG is to assess the efficacy of various antiarrhythmic agents, digitalis, and antianginal drugs. (5) Another purpose for obtaining the Holter monitor ECG is to document ischemic events by recognizing S-T segment and/or T wave abnormalities, especially at rest or during sleep. This is particularly valuable when the chest pain is atypical and when the exercise electrocardiogram is equivocal. Conversely, the patient's complaints may be totally unrelated to ischemic manifestations or any cardiac arrhythmias. (6) In addition, the status of artificial pacemaker function can be assessed by the Holter monitor ECG. (7) Many other clinical applications of the Holter monitor ECG have been described also.

Ambulatory Care↗
PubMed1979

Runaway pacemaker. Unpredictable pacemaker failure.

The runaway pacemaker is an uncommon but very serious complication of permanent artificial pacemakers. Although the runaway pacemaker has been most frequently encountered in older (fixed rate) pacemakers, this problem has also been reported in various types of newer models manufactured by different companies. The most striking finding in our case is that the pacemaker was reported by a reliable pacemaker follow-up service to be working normally only one week before the development of the malfunction. The extremely rapid pacing rate (750 beats per minute) was a manifestation of a far-advanced runaway pacemaker. The manufacturer believes that this is the first reported incident of a runaway pacemaker in this model. This indicates that the runaway pacemaker is still a potential problem, even in newer pacemakers, and reemphasizes the unpredictable and serious nature of this medical emergency.

Aged↗
PubMed1978

Sick sinus syndrome due to cardiac amyloidosis.

In a patient suffering from cardiac amyloidosis a case of sick sinus syndrome, manifested by markedly prolonged recovery time of the sinus node, was documented by an atrial pacing study. The first A-V junctional escape interval was markedly prolonged following the termination of the atrial pacing, pointing to a coexisting A-V nodal dysfunction. The patient required a permanent artificial pacemaker implantation.

Amyloidosis↗
PubMed1977

Wolff-Parkinson-White Syndrome--current views.

The Wolff-Parkinson-White (WPW) syndrome is an important clinical entity because of frequent recurrences of very rapid tachyarrhythmias. The electrocardiographic finding of the WPW syndrome often mimicks pseudo diaphragmatic (inferior) myocardial infarction which should not be misinterpreted. The most important diagnostic criterion is recognition of a delta wave; the short P-R interval or broad QRS complex may not be present in every case. The mechanism for the tachycardia is considered to be a reentry phenomenon via anomalous and normal atrioventricllar (A-V) pathways. The drug of choice for the treatment of regular supraventricular (reciprocating) tachycardia with narrow QRS complexes, which is the most common arrhythmia in the WPW syndrome, is propranolol. Digitalis is almost equally effective in this case. For tachyarrhythmias, particularly atrial fibrillation or flutter with anomalous conduction, intravenously-administered lidocaine is considered to be the drug of choice. Procainamide or quinidine is also frequently used under this circumstance with excellent therapeutic result. Many patients with the WPW syndrome require long-term maintenance drug therapy (propranolol, digitalis or quinidine in most cases). In urgent clinical situations, direct current (DC) shock should be applied immediately. In selected patients with refractory tachyarrhythmias, the use of an artificial pacemaker or surgical approach may be considered.

Anti-Arrhythmia Agents↗
PubMed1977

Drug-induced cardiovascular diseases.

A wide variety of drugs may be associated with serious cardiovascular toxicity. Toxicity due to drugs primarily used for treating cardiovascular toxicity. Toxicity due to drugs primarily used for treating cardiac disorders is the most extensively documented, especially the arrhythmias due to digitalis glycosides. Various arrhythmias are also caused by toxic levels of many antiarrhythmic agents including quinidine, procainamide and phenytotin. Myocardial depression and heart failure are serious side-effects of beta-adrenoceptor blocking agents and myocardial ischaemia due to sympathominetic amines may result from both direct and indirect mechanisms. The many toxic reactions in the cardiovascular system due to non-cardiac drugs are less widely known and for the most part less clearly understood. Many remain controversial at the current time; for example, the diathesis toward thromboembolism in women taking oral contraceptives. Potential cardiac toxicity due to drugs used in the rapidly expanding sphere of anti-neoplastic chemotherapy is exemplified by the cardiomyopathy-like toxicities of doxorubicin and daunorubicin. Many of the psychotherapeutic drugs including phenothiazine antipsychotics and tricyclic antidepressants have arrhythmogenic potential.

Adrenal Cortex Hormones↗
PubMed1976

Unusual electrocardiographic finding--bifascicular block due to hyperkalemia.

A unique case in which the patient had bifascicular block consisting of right bundle branch block and left posterior hemiblock as a result of marked hyperkalemia is presented. To our knowledge, this is the first reported case in which such unusual electrocardiographic abnormalities due to hyperkalemia were demonstrated. The electrocardiographic abnormalities produced by hyperkalemia in this case disappeared promptly by hemodialysis, as the serum potassium level returned to normal. It has been stressed that hyperkalemia should be considered as an important etiologic factor in the differential diagnosis of bundle branch block, hemiblocks and bifascicular block, particularly when these intraventricular blocks are produced suddenly.

Bundle-Branch Block↗
PubMed1976

Coexisting ventricular and blocked atrial parasystole.

A rare instance showing non-conducted atrial parasystole coexisting with ventricular parasystole is presented and a related subject is briefly discussed. The importance of recognizing parasystole is again emphasized because the ordinary extrasystoles, particularly ventricular in origin, are frequently digitalis-induced, while parasystole, which superficially resembles the ordinary extrasystoles, does not seem to be related to digitalis.

Cardiac Complexes, Premature↗
PubMed1976

Artificial cardiac pacing. 1. Indications.

With increasing use of artificial cardiac pacing, criteria for selection of patients have been refined. In general, the most important indication for pacing is the presence and severity of symptoms due to bradyarrhythmias. Use of pacing in acute myocardial infarction remains controversial, but some guidelines are presented here.

Acute Disease↗
PubMed1976

Artificial cardiac pacing: 2. follow-up and complications.

Following insertion or implantation of an artificial cardiac pacemaker, both physician and patient are involved in aftercare to monitor the patient's cardiac status, the condition of the implantation site, and the function of the pacemaker. Among the complications that may occur are pacemaker malfunction and perforation of the ventricles. The physician and patient must also be alert to the possibility of electrical interference and to the physiologic factors that can modify pacemaker function.

Arrhythmias, Cardiac↗
PubMed1975

Reappraisal of hemiblock.

The left bundle branch separates into the left anterior and the left posterior divisions. The impulse travels to the left ventricle via both divisions when they are intact. When one division is blocked, the diagnosis is hemiblock. Diagnostic criteria for left anterior hemiblock are marked left axis deviation, small Q wave in lead I and small R wave in lead III, little or no prolongation of the QRS interval, and no evidence of other causes of left axis deviation. Criteria for left posterior hemiblock are marked right axis deviation, small R wave in lead I and small Q wave in lead III, little or no prolongation of the QRS interval, and no evidence of other causes of right axis deviation. A pure form of hemiblock is not uncommon, especially during acute anterior myocardial infarction, but right bundle-branch block often coexists with hemiblock. Like left bundle-branch block, hemiblocks rarely occur in healthy persons. They are commonly associated with coronary or hypertensive disease or both and are less commonly associated with cardiomyopathies and calcified aortic disease.

Bundle-Branch Block↗
PubMed1974

Cardiac tumors.

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Arrhythmias, Cardiac↗