The American journal of cardiology
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The modes of regression of very high degrees of atrioventricular nodal block (> or = 8:1) were studied in patients with atrial flutter and a specific variant of the tachycardia-bradycardia syndrome. The occurrence of reverse alternating Wenckebach periods, previously reported only in 2:1 atrioventricular block, emphasizes the complexities of multilevel block.
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Children with complete heart block following surgery for congenital heart diseases were prospectively followed to assess the timing for recovery of atrioventricular conduction, and to determine if there were clinical variables that reliably predict permanent heart block. Recovery of atrioventricular conduction occurred by postoperative day 9 in 97% of patients with transient heart block.
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Randomized Controlled Trial Multicenter Study Comparative Study Clinical Trial
Impact of time to treatment with tissue plasminogen activator on morbidity and mortality following acute myocardial infarction (The second National Registry of Myocardial Infarction).
This study examines the association between time to treatment with thrombolytic therapy and hospital outcomes in patients with acute myocardial infarction (AMI) enrolled in a national registry. A total of 71,253 patients hospitalized with AMI from June 1994 to July 1996 who received tissue plasminogen activator (t-PA) therapy in 1,474 United States hospitals were studied. In this study sample, approximately 39% of patients presented to participating hospitals within 2 hours of acute symptom onset and received t-PA; 36% were treated within 2.1 to 4 hours, 12% between 4.1 to 6 hours, and the remaining 13% thereafter. ⋯ The incidence of sustained ventricular arrhythmias declined with progressively longer time to administration of t-PA. The results of this multihospital observational study suggest that patients with AMI treated earlier with t-PA are significantly more likely to survive the acute hospitalization than patients treated later. These data reinforce the benefits to be gained by treatment with t-PA as soon as possible following the onset of acute ischemic symptoms, and for community-wide efforts to reduce the duration of prehospital delay in patients with acute coronary disease.
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In this study, we sought to determine the use of transesophageal echocardiography (TEE) as the primary imaging technique to assist in the placement of endovascular catheters during minimally invasive, port-access cardiac surgery. The recent development of endovascular catheters that are placed via the femoral artery and vein has enabled patients to be placed on cardiopulmonary bypass without the need for direct visualization of the heart or great vessels via sternotomy. This has allowed cardiac surgery to be performed through smaller thoracotomy incisions. ⋯ TEE was able to adequately visualize the cardiac structures and assist in the placement of the endovascular catheters in all patients. Fluoroscopy was only helpful as an aid to TEE for placement of the coronary sinus catheter. TEE is an excellent imaging modality for the proper placement of these new endovascular catheters, obviating the need for fluoroscopy, except to be on standby and for placement of the coronary sinus catheter.
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It has been shown that beta-adrenergic blocking agents may reduce the rate of aortic root dilation and the development of aortic complications in patients with the Marfan syndrome. This may be due to beta-blocker-induced changes in aortic stiffness, of which distensibility and pulse wave velocity are in vivo measurable derivatives. We studied changes in distensibility at 4 levels of the aorta and pulse wave velocity along the entire aorta after 2 weeks of beta-blocker therapy in 6 Marfan syndrome patients and in 6 healthy volunteers, using magnetic resonance imaging (MRI) combined with brachial artery blood pressure measurements. ⋯ At baseline, the Marfan syndrome patients exhibited decreased distensibility at the level of the ascending aorta (2 +/- 1 vs 6 +/- 2 10(-3)mm Hg(-1), p <0.01) and increased pulse wave velocity (6.2 +/- 0.4 vs 3.9 +/- 0.4 ms(-1), p <0.01) compared with control subjects. Only the Marfan syndrome patients had a significant increase in aortic distensibility at multiple levels and a significant decrease in pulse wave velocity after beta-blocker therapy (ascending aorta distensibility: 2 +/- 1 vs 4 +/- 1 10(-3)mm Hg(-1), p <0.05; abdominal aorta distensibility: 5 +/- 2 vs 8 +/- 3 10(-3)mm Hg(-1), p <0.05; pulse wave velocity: 6.2 +/- 0.4 vs 5.0 +/- 1.0 ms(-1), p <0.05). Thus, aortic stiffness in Marfan syndrome, together with mean blood pressure, is reduced by beta-blocker therapy, and MRI is well suited to detect these changes by measuring distensibility and pulse wave velocity.