International journal of cardiology
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Atrial fibrillation and atrial flutter are common arrhythmias after coronary artery bypass grafting. Although the consequences of the arrhythmia are generally not life-threatening, it constitutes a major clinical problem often requiring conversion to sinus rhythm. ⋯ This article reviews the literature on epidemiology, electrophysiology, risk factors, and preventive trials. The major conclusions are: (1) In patients undergoing coronary artery bypass surgery, the incidence of postoperative atrial fibrillation or flutter is 20-30%, the peak incidence being on the second or third postoperative day. (2) The strongest independent preoperative predictor for atrial fibrillation or flutter is the patients' age. (3) Intra-atrial conduction delay recorded pre and peroperatively may predict development of atrial fibrillation. (4) Peroperative inducibility of atrial fibrillation by pacing the right atrium may identify patients at risk for postoperative atrial fibrillation. (5) Development of postoperative atrial fibrillation or flutter has not been associated with peroperative or postoperative events. (6) The specificity and sensitivity of age and other possible relevant factors for prediction of atrial fibrillation or flutter after coronary artery bypass grafting is low. (7) No effective prophylactic regimen has yet been established.
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Comparative Study
Ventriculoarterial coupling during exercise in normal human subjects.
To examine the relative roles of ventricular contractility and loading conditions for cardiovascular adjustment during exercise, 10 normal human subjects were studied using a framework of ventriculoarterial coupling. Anaerobic threshold was evaluated to determine the work rates of aerobic and anaerobic exercise. Ventricular contractile properties were quantified by the slope of the end-systolic pressure-volume relationship (ventricular elastance) and arterial system properties were expressed by the end-systolic pressure-stroke volume relationship (arterial elastance). ⋯ In contrast to aerobic exercise, ventricular elastance rose substantially by 89% in association with about a 10 times increase in plasma norepinephrine. Arterial elastance remained the same as in aerobic exercise. Thus, the increase in stroke volume was primarily mediated by changes in loading conditions during aerobic exercise and by enhanced contractility during anaerobic exercise.
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In order to assess the ability of echocardiography in the detection of intracardiac and extracardiac shunts, we studied 11 patients (aged 22-64 yr) with a continuous precordial murmur using transthoracic and transesophageal echocardiography, and correlated the results with the subsequent angiographic and surgical findings. We found that only in 5 of 6 patients with a patent arterial duct could the continuous flow pattern be detected in pulmonary artery using transthoracic echocardiography, whereas it could be readily and accurately identified by transesophageal echocardiography in all patients. The diameters of the patent arterial duct were also measured and found to be in good correlation with subsequent surgical findings (r = 0.98, p less than 0.05). ⋯ In 2 patients with coronary artery fistula, the origin and site of drainage of the coronary artery could be imaged using transesophageal echocardiography, but the course of coronary artery fistula was more easily detected by transthoracic echocardiography. In one patient with aortopulmonary window, the defect between ascending aorta and main pulmonary artery could readily be imaged by transesophageal echocardiography. We therefore recommend transesophageal echocardiography when evaluating patients with precordial continuous murmur in whom intracardiac and extracardiac shunts or defects are suspected.
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Fifty specimens of double outlet right ventricle were studied. The insertion of the outlet (infundibular) septum determines two types of infundibular interrelationships. In the first type, with anterior and posterior infundibulums, the outlet septum is inserted to the anterior limb of the septomarginal trabeculation; the posterior infundibulum is related with the atrioventricular orifices and the interventricular septum forms exclusively one of the walls of the posterior infundibulum. ⋯ The insertion of the outlet septum permits one to determine the infundibular interrelationships, information which cannot be attained by taking into account the relationship of the great arteries with each other. Once the infundibular interrelationship is established, one must determine if the aorta is connected with the posterior or with the medial infundibulum, since, depending on the anatomical constitution of these infundibulums, there is the possibility of a ventricular septal defect being related with this artery. This information is indispensable before attempting the surgical correction of the double outlet right ventricle and it may be obtained by echocardiography or by angiocardiography.
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We describe a simple, non-invasive and practical method to determine the peak velocity of tricuspid regurgitant flow (and hence derive systolic pulmonary artery pressure) from examination of the dynamics of retrograde tricuspid flow on Doppler. Based on a previously described relationship between right ventricular systolic pressure and the time interval between pulmonary valve closure and tricuspid valve opening, our technique does not require the peak tricuspid regurgitant velocity to be recorded; nor, as in previous studies does it rely upon recording the jugular venous pulse, right ventricular apexcardiogram or invasive pressure measurements. ⋯ The peak tricuspid regurgitant velocity could be predicted from the interval between pulmonary closure and the end of the tricuspid regurgitant signal on Doppler in patients with pulmonary hypertension and those with right ventricular disease with normal pulmonary artery pressure, but not in patients with dilated cardiomyopathy. In patients with pulmonary hypertension or right ventricular dilatation, this may be a useful alternative method in estimating pulmonary artery pressure from Doppler, in cases where it is not possible to record the peak tricuspid regurgitant velocity.