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Query: UMLS:C0022116 (ischemia)
 91,303 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We present clinical and electrophysiological data on 9 patients with paroxysmal reciprocating sinus tachycardia (PRST) of whom only 6 described palpitations. Sinus node disease was present in 5 and cardiac ischemia and/or hypertension in another 3; the remaining case had apparently coincidental Wolff-Parkinson-White (WPW) syndrome. PRST could be initiated in all cases, and terminated in the 4 in whom it was sustained, by suitably timed atrial premature beats over a zone that was dependent on the effective atrial extrastimulus coupling interval (A1-A2) in the high right atrium (HRA). The sequence of atrial depolarization during PRST was similar to that of sinus beats although minor changes in both the P wave and the configuration of the HRA electrogram were observed in half the cases. During paroxysms, cycle length variation and sensitivity to alterations in vagal tone were common. In 6, paroxysms could be initiated by moderately rapid atrial pacing. Repetitive attacks were usually initiated by increases in the sinus rate and not be an antecedent premature atrial extrasystole. Verapamil suppressed sinus node reentry in 5 patients while small doses of atropine favored initiation in 3. PRST was seen in association with AV reentry tachycardias in the patient who had the WPW syndrome.
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PMID:Paroxysmal reciprocating sinus tachycardia. 59 Feb 95

Accurate electrocardiographic diagnosis of myocardial ischemia or infarction is difficult in patients with the Wolff-Parkinson-White syndrome; however, myocardial ischemia may also have profound effects on the electrophysiologic characteristics of the bypass tract in these patients. Comparison of studies performed during and two months following an episode of significant myocardial ischemia demonstrated substantial prolongation of the refractoriness of the bypass tract during the period of ischemia. Bypass refractoriness was prolonged by 196 msec, yet atrioventricular nodal refractoriness was not significantly different from normal. These studies, therefore, suggest that, on occasion, the presence of acute myocardial ischemia may, in fact, obscure the electrocardiographic diagnosis of the Wolff-Parkinson-White syndrome.
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PMID:Wolff-Parkinson-White syndrome. Alterations in electrophysiologic characteristics of the bypass tract secondary to ischemia. 88 79

In a patient with Wolff-Parkinson-White syndrome and an inferior-posterior bypass tract, transient restoration of normal conduction occurred during an attack of angina. The ECG pattern of inferior posterior ischemia was present when the conduction was normal. Thallium scintigraphy showed a reversible posterolateral perfusion defect. The possible mechanisms for production of intermittent preexcitation are discussed.
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PMID:Alternating Wolff-Parkinson-White syndrome associated with attack of angina. 238 30

The hypothesis that production of ischemia or cooling of an arrhythmogenic area or pathway could interrupt tachycardias was tested by subselective catheterization of the coronary artery supplying the site of origin of ventricular tachycardia (9 patients), the accessory pathway (2 patients) and the site of origin of atrial tachycardia (1 patient). Ventricular tachycardia was reproducibly terminated and reinduction temporarily prevented in 8 of the 9 patients by occlusion of the artery or administration of iced isotonic saline. Block in the accessory pathway was obtained in 1 of the 2 patients with Wolff-Parkinson-White syndrome. Selective cooling through the atrioventricular nodal artery in 1 patient terminated his circus movement tachycardia. Reproducible termination of a continuous atrial tachycardia was obtained by cooling of the atrial branch supplying the site of origin of the arrhythmia. These data demonstrate the feasibility of identification and selective catheterization of the coronary artery branch supplying blood to an arrhythmogenic area or pathway and suggest a new possibility for treatment of tachycardias by permanently blocking the blood supply to the site of origin or pathway of a tachycardia.
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PMID:Termination of tachycardias by interrupting blood flow to the arrhythmogenic area. 341 15

The case reported herein illustrates an unusual form of nonobstructive hypertrophic cardiomyopathy which was associated with Wolff-Parkinson-White syndrome, myocardial ischemia and necrosis despite normal coronary arteries. The patient is unique since the hypertrophied myocardial segment was localized exclusively to the posterolateral free wall. Quantitative thallium-201 scintigraphy demonstrated reversible ischemia that corresponded precisely with this region of posterolateral hypertrophy. While the exact mechanism for ischemia in patients with hypertrophic cardiomyopathy and normal coronary arteries remains controversial, a functional rather than anatomic disturbance of blood flow seems likely.
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PMID:Hypertrophic cardiomyopathy and myocardial ischemia with normal coronary arteries. 360 9

Inferior lead pseudo-infarct Q waves are a common finding in the Wolff-Parkinson-White (WPW) syndrome. In a retrospective study of previously published cases of WPW, pseudo-infarct Q waves in the inferior leads were associated with positive or isoelectric T waves in 47 of 50 examples (94%). This characteristic Q wave-T wave vector discordance results from secondary repolarization changes due to altered ventricular activation. As a corollary, the presence of T wave inversion with inferior lead Q waves and a short PR interval is strongly suggestive, but not pathognomonic of inferior ischemia.
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PMID:Pseudo-infarct patterns in the Wolff-Parkinson-White syndrome: importance of Q wave-T wave vector discordance. 736 52

Cost-effectiveness analyses were reviewed in the following diagnostic and treatment categories: acute myocardial infarction (MI) and diagnostic strategies for coronary artery disease (CAD), coronary artery bypass graft (CABG) surgery, percutaneous transluminal coronary angioplasty (PTCA), congestive heart failure (CHF), and arrhythmias. In the case of acute MI, coronary care units, as presently used, are rather expensive but could be made much more efficient with more effective triage and resource utilization; reperfusion via thrombolysis is cost-effective, as are beta-blockers and angiotensin-converting enzyme (ACE) inhibitors post-MI in appropriate patients. Cost-effectiveness of CAD screening tests depends strongly on the prevalence of disease in the population studied. Cost-effectiveness of CABG surgery depends on targeting; eg, it is highly effective for such conditions as left-main and three-vessel disease but not for lesser disease. PTCA appears to be cost-effective in situations where there is clinical consensus for its use, eg, severe ischemia and one-vessel disease, but requires further analysis based on randomized data; coronary stents also appear to be cost-effective. In preliminary analysis, ACE inhibition for CHF dominates, ie, saves both money and lives. Cardiac transplant appears to be cost-effective but requires further study. For arrhythmias, implantable cardioverter defibrillators are cost-effective, especially the transvenous device, in life-threatening situations; radiofrequency ablation is also cost-effective in patients with Wolff-Parkinson-White syndrome apart from asymptomatic individuals; and pacemakers have not been analyzed except in the case of biofascicular block, where results were variable depending on the situation and preceding tests.
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PMID:Cost-effectiveness analysis in heart disease, Part III: Ischemia, congestive heart failure, and arrhythmias. 787 Nov 79

Atrial fibrillation is the most common atrial tachyarrhythmia. Consideration for the potential conversion of atrial fibrillation and the subsequent maintenance of sinus rhythm may be related to underlying pathology. Typically, extra cardiac factors such as thyroid hyperactivity help to determine initial therapy. Intrinsic cardiac factors may also influence the clinician's decision regarding potential cardioversion and maintenance of sinus rhythm. Some acute events such as pericarditis and the effects of cardiac trauma may resolve and result in spontaneous restoration of sinus rhythm. Other cardiac events such as acute myocardial infarction with or without atrial ischemia, valvular disease, and others may result in the precipitation of atrial fibrillation. The major reasons to consider cardioversion, either medically or electrically, are ventricular rate control, hemodynamic improvement, sense of well being, and the avoidance of embolism. Certain clinical situations (e.g., Wolff-Parkinson-White syndrome) require urgent restoration of sinus rhythm in light of the potential for extremely rapid ventricular rates. It has been suggested that all antiarrhythmic drug administration should be initiated in the hospital setting, but the brief period of drug administration in an inpatient setting does not protect the patient from potential, late-onset proarrhythmic events. Both antiarrhythmic drug therapy and electric cardioversion are useful for restoration of sinus rhythm in both acute and chronic atrial fibrillation. The most important negative aspect of drug conversion of atrial fibrillation may be the potential development of a proarrhythmic drug effect. Although controversial, conversion (medical or electrical) is probably indicated in every patient with the first episode of persistent atrial fibrillation, even if the patient is asymptomatic.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Should every patient with atrial fibrillation have the rhythm converted to sinus rhythm? 788 9

The utility of body surface potential mapping to improve interpretation of electrocardiographic information lies in the presentation of thoracic surface distributions to characterize underlying electrophysiology less ambiguously than that afforded by conventional electrocardiography. Localized cardiac disease or abnormal electrophysiology presents itself electrocardiographically on the body surface in a manner in which pattern plays an important role for identifying or characterizing these abnormalities. Thus, in myocardial infarction, transient myocardial ischemia, Wolff-Parkinson-White syndrome, or ventricular ectopy, observation of electrocardiographic potential patterns, their extrema, and their magnitudes permits localization and quantization of the abnormal activity. Conventional electrocardiography assesses pattern information incompletely and does not use information of distribution extrema locations or magnitudes. Thus, increases or decreases in the magnitudes of electrocardiographic features (ST-segment potential displacement, amplitude, or morphology of Q, R, S, or T waves) associated with changes in cardiac sources (ischemia, infarction, conduction abnormalities, etc.) as measured from fixed leads have a high likelihood of being misinterpreted if the distribution itself is changing. In this study, the authors demonstrate the utility of estimating distributions from small numbers of optimally selected leads, including conventional leads, to reduce uncertainty in the interpretation of electrocardiographic information. This issue is highly relevant when thresholds are used to detect significance of potential levels (exercise testing, detection of myocardial infarction, and continuous monitoring to assess ST-segment changes). Significance of this work lies in improved detection and characterization of abnormal electrophysiology using conventional or enhanced leadsets and methods to estimate thoracic potential distributions.
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PMID:Estimating ECG distributions from small numbers of leads. 865 36

We present a case of WPW syndrome with an accessory pathway in the right free wall. Two prolonged and failed attempts at radiofrequency catheter ablation of this accessory pathway in other institutions led to a third attempt in our hospital. With a 7F catheter in the right coronary artery, transient ischemia in the right ventricular myocardium developed with consecutive loss of bidirectional preexcitation within 45 seconds prior to catheter ablation. Removal of the guiding catheter, while the mapping catheter in the coronary artery was still in place, was reproducibly followed by the reoccurrence of the preexcitation pattern. Successful outcome of accessory pathway ablation was achieved by mapping the right free wall using an intracoronary catheter in the right coronary artery and ablating the accessory pathway using a modified long vascular sheet.
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PMID:[Transient loss of preexcitation by acute coronary ischemia--a case report]. 965 53


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