Herz
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The percentage of ischemic strokes or peripheral arterial embolism attributed to cardiogenic embolism is about 30% and 75%, respectively. Diagnostic work-up in patients with prior arterial embolism is of prognostic importance, because embolic events are often recurrent. Cardioembolic sources with major risk of embolism are atrial fibrillation, mechanical or biological heart valve prosthesis, left ventricular or left atrial thrombi, left atrial myxomas, bacterial endocarditis, nonbacterial thrombotic endocarditis and nonischemic dilative cardiomyopathies. ⋯ Only left ventricular thrombi could be better evaluated by the transthoracic method, because visualization of the left ventricular apex by the transesophageal approach is problematic. In patients with systemic arterial embolism the combination of transthoracic and transesophageal echocardiography is the diagnostic method of choice to detect a cardioembolic source. Randomized studies in the future must prove, whether the echocardiographic findings can lead to better therapeutic strategies to improve the prognosis of patients with embolic disease.
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Orthostatic hypotension and related neurologic symptoms are frequently encountered in clinical practice. The maintenance of appropriate blood pressure and heart rate responses upon assuming the upright posture are dependent upon: 1. intact mechanical (venous valves) mechanisms, 2. functioning arterial and cardiopulmonary baroreceptors, 3. normal peripheral neural pathways, 4. normal central neural integration, and 5. appropriate neurohormonal secretion. Dysfunction at one or more of these loci may facilitate the occurrence of orthostatic hypotension and syncope. ⋯ Cardioinhibitory CSH is the most common, and in its purest form consists of sinus bradycardia or arrest, asystole or AV block during carotid sinus massage. This vagally-mediated response is eliminated by atropine. Cardiac pacing is nearly universally successful in preventing severe symptoms.(ABSTRACT TRUNCATED AT 400 WORDS)
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The decision to anticoagulate patients with atrial fibrillation (AF) involves weighting the risk of an embolic event without therapy versus the risk of a hemorrhagic event on therapy. Improved methods of monitoring anticoagulation with the International Normalized Ratio (INR), and recent evidence of the efficacy and safety of low-dose warfarin (INR range 2.0 to 3.0) have clarified the role of anticoagulation in AF. Over the past four years, five large prospective randomized trials in patients with nonvalvular atrial fibrillation (NVAF) have reported substantial reductions in stroke in patients treated with low-dose warfarin therapy. ⋯ The role of aspirin in AF is less clear as only two of the five prospective trials randomized patients to aspirin therapy and only one documented aspirin benefit. Therefore, aspirin appears to offer less benefit but is a satisfactory alternative to warfarin therapy. Aspirin is currently recommend for patients who are poor candidates for anticoagulation or individuals with AF who are considered to be at low risk for stroke.
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In patients with Wolff-Parkinson-White syndrome the accessory pathway may participate in various tachyarrhythmias thereby influencing symptoms and prognosis. Atrial fibrillation occurs in 10 to 32% of patients and may have life-threatening consequences by precipitating ventricular fibrillation in patients with rapid conduction due to an accessory pathway with short anterograde refractory period (< 250 ms). Pathogenesis of atrial fibrillation in the WPW syndrome and therapeutic options are reviewed in this presentation. ⋯ Anterograde conduction properties of the pathway appear to be more important than retrograde properties. High incidence of atrial fibrillation is related to short anterograde refractory periods, and of note, this arrhythmia is rare (3%) in patients with concealed pathways. With intracardiac recordings, Jackman et al. could demonstrate atrial fibrillation due to micro-reentry originating in accessory pathway networks.(ABSTRACT TRUNCATED AT 250 WORDS)
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In the past eight years until July 1992, 92 patients were admitted in the acute state of aortic dissection within two weeks from the onset of symptoms. 41 were diagnosed as Stanford type A and 51 were type B by transthoracic and transesophageal echography, computer tomography, and surgery. Sensitivity of transesophageal echography to detect the intimal flap and the false lumen was 97.6% in patients with Stanford type A and 100% in patients with Stanford type B. The surgical decision making has been mostly depending on the transesophageal echographic diagnosis. ⋯ Secondary repair of the aortic arch was required due to ischemia of the aortic arch vessels in two patients after the primary surgery. The extension of the dissection into the aortic arch vessels can be promptly diagnosed with the combination of transesophageal echography and transcutaneous echography. In conclusion, transesophageal Doppler echography is the most rapid diagnostic tool for decision making in acute aortic dissection, and intraoperative transesophageal echo can provide useful information to resolve the perfusion difficulties during cardiopulmonary bypass.(ABSTRACT TRUNCATED AT 400 WORDS)