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Query: UMLS:C0038454 (stroke)
 147,016 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Framingham Study showed that Atrial Fibrillation (AF) exposes the patient to an increased stroke risk and to low cardiac output. It is well known that the mechanism of Atrial Fibrillation is reentry. In order to facilitate AF's studies, we propose a deterministic model that can be used for cardiac signal characterization. The model is based on a linear combination of several "Atrial Flutter-like signals. We obtained AF-close aspects. To demonstrate its usefulness we performed a power spectrum transform (i.e. scalar Fast Fourier Transform) of this model. Thanks to the model we show that this transform cannot be used as is, and may induce errors in results interpretation. We also show based on the same example how to overcome the limitation with help of the model. We expect that this model will help in mathematical transforms relevance evaluation. This may lead to new findings in AF classification, and to improvement in patients' treatment, follow-up and survival.
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PMID:Atrial heart fibrillation modeling: a tool for adequate choice of signal processing functions. 1118 25

Atrial flutter (AFl) is an arrhythmia resulting from reentry in a macroreentrant circuit, most commonly in the right atrium. Typical AFl uses the narrow isthmus of right atrial tissue between the tricuspid valve annulus and the inferior vena cava orifice as part of the macroreentrant circuit. The treatment of AFl is directed toward achieving the following four goals. 1) In the presence of AFl, adequate rate control is required, which can be achieved in most but not all patients by oral or intravenous digoxin, calcium channel blockers, or beta-blockers, alone or in combination. 2) Anticoagulation with warfarin should be considered in patients with recurrent AFl, especially those over 70 years of age, and those with a history of atrial fibrillation, stroke, or structural heart disease. 3) Conversion to sinus rhythm can be achieved in up to 70% of patients with intravenous ibutilide, but this should be reserved for patients with either normal hearts or only mild left ventricular dysfunction. Direct-current cardioversion is nearly 100% effective and is ideal for patients with left ventricular dysfunction. 4) Long-term maintenance of sinus rhythm may be achieved in up to 50% to 60% of patients by using antiarrhythmic drugs, including sotalol, amiodarone, dofetilide, propafenone, and flecainide, but with the potential for causing significant proarrhythmia and side effects. Radiofrequency catheter ablation may cure over 90% of patients with type 1 AFl (using the tricuspid valve to inferior vena cava isthmus), and from 70% to 90% of patients with atypical AFl. Newer mapping techniques, such as electroanatomic mapping, are likely to further reduce procedure time and improve success rates.
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PMID:Atrial Flutter. 1144 58

Two hundred and fifty-one patients with a persistent foramen ovale (PFO), mean age 43.3 +/- 12.4 years, underwent catheter closure between 6/1995 and 6/2001. One hundred and forty-one had an ischemic stroke, 99 a transient ischemic attack (TIA) or prolonged reversible ischemic neurologic deficit, 5 peripheral arterial embolism, 4 suffered from decompression sickness after diving and 2 had transient global amnesia. Fifty-nine of them had multiple events in spite of antiplatelet or anticoagulant therapy. The patients received five different devices: 13 Rashkind Occluders, 20 Amplatzer septal Occluders, 109 Amplatzer PFO-Occluders, 73 CardioSEAL and 36 STAR-Flex devices. Time of fluoroscopy was 8.3 +/- 4.5 min. In three patients a device embolized and had to be removed from the groin vessels. We saw five inguinal or retroperitoneal venous hematomas with the need for operation in one patient. One early and one late perforation of the left atrium caused by a guide wire and a left-atrial disc, respectively, also needed surgery. Fourteen patients had documented late arrhythmias. Six patients with atrial fibrillation needed drugs or cardioversion while the other patients with runs of supraventricular tachycardia, atrial flutter and multiple extrasystoles needed no therapy. On transesophageal echocardiography (TEE) 6 months after implantation we found four significant residual leaks. These patients had the defect closed with a second device. In addition a secundum atrial septal defect (ASD) was closed in 17 patients (mean age 38 +/- 10.5 years) with Amplatzer septal Occluders (12) and CardioSEAL devices (5). These patients had experienced eight strokes and nine TIAs, 3 of them had had multiple events. Two of these patients had a significant residual defect and one had atrial flutter following the procedure. Two hundred and two PFO-patients and 12 ASD patients were followed for 6-62 (24.6 +/- 14.2) months; 2 died due to a traffic accident and a myocardial infarction, respectively. Four patients had another neurologic event following PFO-closure. We now overlook 210 patients with 348.6 symptom-free patient years and have a 1-year recurrence rate of neurologic events of 1.9%. Catheter closure of the PFO and atrial septal defect is a simple, effective and quick method which ensures a high closure rate, avoids life-long anticoagulation and has a low recurrence rate of neurologic events.
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PMID:[Interventional occlusion of foramen ovale and atrial septal defects after paradoxical embolism incidents]. 1244 68

Ischemic stroke is usually a manifestation of arteriosclerosis in the elderly patient. The major risk factors are age and high blood pressure; prevention is particularly successful in hypertensives. All known antihypertensive agents can be applied, and ACE inhibitors and the lipid-lowering agents, in particular the statins are now well established. That said, under certain circumstances it might be of importance to pay greater attention to the other lipid fractions. It is currently estimated that only one-third of patients with a disturbance of lipid metabolism actually receives treatment. Results of treatment in the acute phase of apoplexy have been improved by the establishment of stroke units that provide the facilities for intensive and comprehensive management of stroke victims. Inhibitors of platelet aggregation, in particular aspirin, now have a permanent role in the acute and follow-up phase. For specific risk factors such as stenosis of the carotid artery or atrial flutter, special therapeutic guidelines apply.
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PMID:[Drug therapy of stroke in the stroke unit. A race against time]. 1265 24

This report presents the outcome of a cohort of 94 patients with atrial fibrillation from the Canadian Registry of Atrial Fibrillation, in which we paid particular attention to the probability of stroke and death. We also evaluated warfarin use over time and compared left atrial dimensions in patients with atrial flutter with those with atrial fibrillation.
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PMID:Prognostic differences between atrial fibrillation and atrial flutter. 1499 2

Definitions, classification, surface electrocardiographic characterisitics, risk for stroke and treatments. Atrial flutters are macro-reentrant circuits originated from both right and left atria. They have been classified in typical and atypical based on their cavo-tricuspid isthmus-dependence. Typical atrial flutter comprises counterclockwise and clockwise isthmus-dependent atrial flutter located within the right atrium. Atypical atrial flutters are composed by non-isthmus-dependent right atrial flutter and left atrial flutter. Typical atrial flutter represents at least 90% of all flutters, and has usually a counterclockwise pattern. Ablation is a potential definitive therapy for atrial flutter. However, successful procedures as well as complications rates are different depending of the location of the circuit. There are now evidences for risk of stroke related to atrial flutter, although epidemiological studies have not been conducted yet. Therefore, prevention of such complications using anti-thrombotic should be performed as done for atrial fibrillation.
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PMID:[Typical and atypical atrial flutters]. 1513 29

Arrhythmic shock (AS) results primarily from many types of tachyarrhythmias: atrial fibrillation and flutter, supraventricular tachyarrhythmias, ventricular paroxysmal tachycardias. AS is distinguished from the stable course of the above arrhythmias by pronounced changes in central hemodynamics (CH) and by rapid and frequently negative manifestations. The status of CH is an important criterion when whether electrical cardioversion is performed is decided. CH was studied in 306 patients with genuine cardiogenic shock and in 32 patients with AS. In case of effective cardioversion, central hemodynamics in patients with AS underwent rapid changes: first of all, stroke volume and cardiac index increased and end systolic volume decreased. In case of effective of antishock measures, CH in patients with cardiogenic shock normalized only within 3-4 weeks of their stay at an intensive care unit, but ejection fraction also remained decreased at their discharge from hospital.
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PMID:[Cardioversion and central hemodynamics in patients with arrhythmic and genuine cardiogenic shock]. 1607 53

Atrial fibrillation and atrial flutter are important risk factors for stroke. Based on a literature search, pathogenesis of thromboembolism, risk assessment in patients, efficacy of anticoagulation therapy and its alternatives are discussed. Special emphasis is put on issues like paroxysmal atrial fibrillation, atrial flutter and anticoagulation surrounding catheter ablation and cardioversion. A strategy for anticoagulation around the time of pulmonary vein ablation is suggested.
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PMID:Anticoagulation in atrial fibrillation and flutter. 1608 16

Atrial tachyarrhythmias, usually atrial fibrillation or atrial flutter, are the most common complications of cardiac surgery. Atrial tachyarrhythmias are associated with patient discomfort/anxiety, hemodynamic deterioration, cognitive impairment, thromboembolic events (including stroke), exposure to the risks of antiarrhythmic treatments, longer hospital stays and increased costs. Many approaches to the prevention of postoperative atrial tachyarrhythmias have been studied. Of these, studies using perioperative beta-blocking agents or amiodarone provide level A evidence of efficacy and, in properly selected patients, have shown a high degree of safety. Less convincing, level B evidence exists for the use of postoperative temporary atrial pacing and for perioperative intravenous magnesium treatment. The treatment of postoperative atrial tachyarrhythmias is similar to those occurring in other settings and includes excluding other potential causes of atrial tachyarrhythmias, antithrombotic or anticoagulation therapy, control of the ventricular response rate and consideration of restoring/maintaining sinus rhythm. The selection of therapies to achieve these goals should consider the sympathetic nervous system discharge state of the postoperative environment and the natural history of postoperative atrial fibrillation, which includes spontaneous resolution of the arrhythmogenic tendency after approximately six weeks. The Canadian Cardiovascular Society Consensus Conference recommendations for the prevention of atrial tachyarrhythmias after cardiac surgery and for the treatment of atrial tachyarrhythmias that occur after cardiac surgery are presented along with evidence that supports these recommendations.
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PMID:Atrial fibrillation following cardiac surgery. 1623 88

Stroke is a significant cause of serious disability and death worldwide. A substantial proportion of strokes are related to an underlying cardiac embolic source, most commonly in association with atrial arrhythmias (fibrillation/flutter). Atrial fibrillation is considered a major risk factor for stroke. Although long-term prophylactic oral anticoagulation has been shown to be very effective in reducing stroke in patients with atrial fibrillation, it has a number of major limitations and is not feasible in all patients. In such cases, the use of percutaneously (transvenous) implanted left atrial appendage occlusive devices or surgical appendage obliteration is being explored. Similarly, the presence of a patent foramen ovale, especially in the presence of an atrial septal aneurysm, is now recognized as an important potential mediator of paradoxical cardiogenic embolism. Percutaneous patent foramen ovale closure is becoming increasingly established as a safe and effective means of preventing recurrent strokes in the presence of a patent foramen ovale. In this account, the authors discuss the intracardiac devices and techniques available and the relative merits of their use for stroke prevention.
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PMID:Intracardiac devices for stroke prevention. 1640 2


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