The American journal of cardiology
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A combined use of noninvasive techniques and electrophysiologic study in the prediction of arrhythmic events was prospectively evaluated in 303 surviving patients of acute myocardial infarction (AMI). The most powerful combination of noninvasive prognostic variables in identifying patients suitable for invasive strategies was also assessed. Patients who had > or = 2 variables among left ventricular ejection fraction < 0.4, ventricular late potentials and repetitive ventricular premature complexes (VPCs) were considered eligible for programmed ventricular stimulation. ⋯ With a good sensitivity (81%), a combined use of noninvasive tests and electrophysiologic study selected a group of post-AMI patients at sufficiently high risk (event rate 65%) to be considered candidates for interventional therapy. The combination of > or = 2 variables among left ventricular ejection fraction < 0.4, filtered QRS duration > or = 106 ms and > or = 2 runs of unsustained VT was superior to the other ones in identifying high-risk subjects (positive and negative predictive values for arrhythmic events of 44 and 99%, respectively). On the basis of the data, this scheme appears to be the most appropriate for selecting patients suitable for electrophysiologic testing and invasive strategies after AMI.
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Comparative Study
Transgastric continuous-wave Doppler to determine cardiac output.
A new method to measure cardiac output using transgastric continuous-wave Doppler was evaluated in 31 consecutive patients undergoing cardiac surgery with simultaneous measurement of cardiac output by the thermodilution technique. A 5 MHz single-plane imaging/5 MHz continuous-wave Doppler transesophageal transducer was used to image the left ventricular outflow tract, aortic valve and ascending aorta from a modified transgastric short-axis plane. The continuous-wave Doppler cursor was aligned parallel with blood flow across the aortic valve to obtain the maximal Doppler velocity spectra. ⋯ The Doppler-derived cardiac outputs were correlated with the simultaneous measurements of cardiac output by the thermodilution technique. Linear regression analysis revealed a close correlation with R = 0.91, SEE = 0.8 liter/min, and y = 1.01x + 0.2 (p < 0.001). In conclusion, transgastric continuous-wave Doppler across the aortic valve is a promising new technique that may be used in selected patients for accurate measurement of cardiac output.
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Comparative Study
A shared pathway in atrioventricular nodal reentrant tachycardia and atrial flutter: implications for pathophysiology and therapy.
Atrioventricular (AV) nodal reentrant tachycardia and atrial flutter are considered 2 distinct supraventricular tachycardias. Recent clinical and experimental data suggest that both these tachycardias include an area in the lower right atrial septum in their reentrant pathways. This study was designed to test the hypothesis that there is an association between the mechanisms of AV nodal reentrant tachycardia and atrial flutter because of a shared pathway of reentry. ⋯ Atrial flutter occurs frequently (15 of 29 patients; 52%) in patients with AV nodal reentrant tachycardia, because of a shared pathway in their reentry circuits. Because of this shared pathway, both arrhythmias can be ablated at the same site. These observations promote new insights into the mechanism and therapeutics of supraventricular tachycardias.
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Two-dimensional echocardiography is the diagnostic procedure of choice for evaluation of prosthetic valve abnormalities. However, transthoracic echocardiography (TTE) may be limited owing to acoustic shadowing and poor acoustic windows. Some of these limitations may be overcome by transesophageal echocardiography (TEE). ⋯ Prosthetic valve endocarditis and thrombi were correctly identified by TTE in 12 of 33 (36%) and 1 of 8 (13%) prostheses, respectively, but could be diagnosed by TEE in 27 of 33 (82%; p < 0.001) and 8 of 8 (100%; p < 0.01), respectively. Compared with TTE, TEE had a higher sensitivity for morphologic prosthetic valve abnormalities in patients with either bioprostheses (88 [87%] vs 66 [65%] of 101 prostheses; p < 0.01) or mechanical devices (19 [83%] vs 5 [22%] of 23 prostheses; p < 0.01) and in patients with a prosthesis in either the aortic (49 [77%] vs 32 [50%] of 64; p < 0.01) or mitral (58 [97%] vs 39 [65%] of 60; p < 0.001) position. Overall, sensitivity and specificity were 57 and 63%, respectively, for TTE, and 86 and 88%, respectively, for TEE.(ABSTRACT TRUNCATED AT 250 WORDS)