A new therapeutic strategy for electrical cardioversion of atrial fibrillation.

BACKGROUND: The conventional approach to cardioversion of atrial fibrillation includes a period of anticoagulation with oral anticoagulant therapy (OAT) extending from 3 weeks precardioversion to 4 weeks postcardioversion. The protocol of rapid anticoagulation (such as that of the ACUTE study) consists of a precardioversion transesophageal echocardiography (TEE) followed by OAT for 4 weeks. In the last few years low-molecular-weight heparins have established themselves as a safe and efficacious alternative to traditional antithrombotic therapies. The aim of this study was to demonstrate that the exclusion of thrombi by precardioversion TEE together with the exclusion of atrial stunning by a second TEE performed after 1 week, to date not suggested in the literature, could reduce to 7 days the period of pericardioversion anticoagulation. This therapy would be carried out using low-molecular-weight heparins with no need for biological monitoring and with the possibility of self-administration. METHODS: We have studied 57 consecutive patients who had atrial fibrillation or flutter with a history of atrial fibrillation lasting > 48 hours. All patients received enoxaparin at a dosage of 100 IU antiXa/kg twice daily before undergoing multiplane TEE. Previous informed consent and ethical committee authorization had been obtained. Twenty-four hours following TEE, in the absence of thrombi and/or spontaneous moderate/severe echocontrast in the atrial chambers, the patients underwent electrical cardioversion and were discharged within 24 hours of sinus rhythm restoration. These patients were prescribed enoxaparin at the indicated dosage twice daily until TEE, performed in an outpatients setting 7 days following cardioversion. In the absence of thrombi and/or atrial and/or left atrial appendage stunning, OAT was terminated. Enoxaparin was associated with OAT for the following 3 weeks if any of the following signs of stunning were present: A wave inferior to the normal value for age at transmitral Doppler; a left atrial appendage emptying velocity < 40 cm/s; the appearance or increase in the severity of spontaneous echocontrast. For all patients, clinical and electrocardiographic follow-up was carried out at 1 month. RESULTS: In one patient TEE was not tolerated and one refused it. In 7 patients cardioversion was not performed: 4 because of the presence of thrombi, 1 because of moderate/severe spontaneous echocontrast and 2 owing to spontaneous cardioversion. Of the remaining 48 patients, cardioversion proved to be efficacious in 38, with sustained sinus rhythm at 1 week in 33 patients. One of these refused the second TEE and of the remaining 32 patients, 24 (75%) showed no signs of stunning at the second TEE and so anticoagulation was terminated. Thus, after 1 week, 75% (24/33) of patients in sinus rhythm could benefit from a shortened anticoagulation therapy which lasted for a mean of only 8.5 days. No patients showed signs of a thromboembolic accident at 1 and 2 months of follow-up. CONCLUSIONS: Most patients undergoing electrical cardioversion for atrial fibrillation could benefit from a shorter period of anticoagulation with low-molecular-weight heparins for 1 week if TEE precardioversion and 7 days postcardioversion excludes thrombi and atrial stunning. The management of patients with atrial fibrillation would be greatly simplified.

Effects of acute intrathoracic pressure changes on left ventricular geometry and filling.

Acute changes in intrathoracic pressure (ITP) affect left ventricular (LV) function. It has been suggested that this functional impairment could be the result of an alteration in LV filling caused by a reduction in LV compliance induced by the rearrangement of biventricular geometry that occurs under these conditions. Therefore, to evaluate the effects of an acute increase or decrease in ITP on LV geometry and filling, we used two-dimensional and Doppler echocardiography to study 25 normal volunteers both during the Müller maneuver (acute decrease in ITP induced by a forced inspiration against a closed airway) and during continuous positive airway pressure breathing. During both maneuvers LV geometry was altered as demonstrated by the significant increase in the normalized curvature radius of the interventricular septum and the unchanged curvature radius of the LV free wall. LV filling was altered during both maneuvers as demonstrated by significant decreases in early peak flow velocity, early-to-late peak flow velocity ratio, and early deceleration rate. Thus, during maneuvers that acutely decrease or increase ITP, alterations in LV geometry occur. These acute distortions of LV geometry may be one of the mechanisms responsible for alterations in LV filling.

Color Doppler evaluation of aortic dissection.

Color Doppler studies were performed in 16 adult patients with proven DeBakey type I and III aortic dissection. Simultaneous opacification of both aortic lumina with oppositely directed flow was noted by color Doppler in at least one aortic segment in 14 of 16 patients (12 type I, two type III). In two patients (one type I, one type III), flow was seen in one lumen only, with clot demonstrated in the other lumen in one of them. Of 12 patients in whom communication between two aortic dissection channels was shown by angiography/surgery, color Doppler correctly identified them in nine patients (four ascending aorta, two aortic arch, and three descending aorta), either by direct visualization of flow moving from one lumen into the other (six patients) or indirectly by analyzing differences in timing of opacification of the two lumina and flow direction (three patients). Also, color Doppler correctly diagnosed aortic regurgitation as severe (aortic regurgitation jet occupying more than 75% of left ventricular outflow) in three patients and moderate in four patients. Color Doppler provides comprehensive evaluation of flow dynamics in aortic dissection.

Prediction of the extent of coronary artery disease with the evaluation of left ventricular wall motion abnormalities during atrial pacing. A cross-sectional echocardiographic study.

UNLABELLED: In patients with coronary artery disease, left ventricular performance during stress is affected by the degree of coronary stenosis. In order to verify whether there exists a relationship between the extent of wall motion abnormalities detectable during atrial pacing and the degree of coronary obstruction, 76 patients, without previous myocardial infarction, were studied. Each patient underwent cross-sectional echocardiography during transesophageal atrial pacing and exercise electrocardiography before coronary angiography. Of the 76 patients, 46 had significant coronary artery disease (stenosis greater than or equal to 75% of at least one major coronary vessel), while 30 had normal coronaries or a stenosis of less than 75%. Eighteen patients had single-, 14 had two- and 14 had three-vessel disease. For each patient a coronary score was obtained: the score used took into consideration the site, number and severity of the stenosis. This score was then correlated with the wall motion score, obtained from the analysis of 9 segments of the left ventricle. A weak correlation was obtained between wall motion score at rest and coronary score (r = -0.42), while the correlation between coronary score and the difference between wall motion score at rest and during transesophageal atrial pacing was slightly better (r = 0.53); this correlation further improved if wall motion score during pacing was considered (r = -0.63). If the patients with discordant diagnostic tests (echocardiography during transesophageal atrial pacing and exercise electrocardiography) were excluded, the correlation coefficient between coronary score and wall motion score during pacing increased even more (r = -0.77). IN CONCLUSION: (1) analysis of wall motion of the left ventricle during atrial pacing is useful for the non-invasive evaluation of the severity of coronary disease; (2) cross-sectional echocardiography during atrial pacing, apart from being a useful diagnostic tool, is also a help in judging the degree of severity of coronary artery disease.

Atrial pacing in the detection and evaluation of coronary artery disease.

Atrial pacing has been recently re-evaluated as a stress test for the detection of coronary artery disease. This sort of stress, especially if used in conjunction with cardiac imaging techniques can be considered a reliable alternative to physical exercise. In patients with recent myocardial infarction it can be usefully and safely utilized to obtain prognostic information. In fact, patients with recent myocardial infarction and a positive electrocardiogram (decreases ST greater than or equal to 1 mm) during atrial pacing more frequently than others present subsequent major cardiac events. Limitations of traditional pacing test (invasivity, poor sensitivity of electrocardiography) can be overcome with a new test we have recently proposed: two-dimensional echocardiography during atrial pacing. We have used this new stress test to detect patients with significant coronary artery disease, to identify patients with myocardial infarction and multivessel disease and to evaluate the effect of coronary artery bypass surgery.

Comparison of postexercise and transesophageal atrial pacing two-dimensional echocardiography for detection of coronary artery disease.

Two-dimensional (2-D) echocardiography during transesophageal atrial pacing (TAP) was recently proposed as an alternative to exercise 2-D echocardiography for the diagnosis of coronary artery disease (CAD). To compare these 2 methods, 78 consecutive patients with good-quality echocardiographic (echo) examinations at rest were studied. Two-dimensional echocardiography was performed immediately after supine bicycle exercise and at peak atrial pacing obtained with transesophageal atrial stimulation. Twenty patients were excluded: 16 because of poor quality of 2-D echo images after exercise and 4 because of inadequate TAP studies (atrial capture not achieved in 2 and intolerance in 2). Of the remaining 58 patients, 39 had significant CAD (at least 75% diameter stenosis of at least 1 major coronary artery) and 19 had no significant CAD. The 2 test responses were considered positive if a wall motion abnormality was detected during pacing or after exercise. Sensitivity and specificity were 82% and 95% after exercise and 90% and 84% during TAP. In patients with significant CAD but without wall motion abnormalities at rest, sensitivity was 75% during pacing and 56% after exercise. In patients with significant CAD, the wall motion score index decreased significantly with both types of stress; during pacing wall motion score index was significantly lower than after exercise. Thus, 2-D echo during TAP appears to be a feasible and reliable alternative to postexercise echo for the detection of CAD.

[Diagnosis of ischemic cardiopathy by 2-dimensional echocardiography carried out after the bicycle ergometry test in the supine position: feasibility, sensibility and specificity]. / Diagnosi di cardiopatia ischemica mediante ecocardiografia bidimensionale eseguita dopo sforzo al cicloergometro in posizione supina: fattibilità, sensibilità e specificità.

We performed two dimensional echocardiography (2D ECO) after bicycle exercise obtained in supine position in 80 patients undergoing coronary angiography for the evaluation of chest pain. Adequate 2D images after exercise were recorded in 64/80 (80%) patients (pts). Forty pts had significative coronary artery disease (CAD), 24 had no CAD. Twenty-three CAD pts had left ventricle wall motion abnormalities (WMA) at rest; 17 pts had 1-, 11 2- and 12 3-vessels disease. The test was considered positive if WMA were present after exercise. Thirty-two CAD pts and 1 pt without CAD had WMA after exercise, thus sensitivity and specificity were, respectively, 80% and 96%. In 1-, 2- and 3-vessels disease pts, sensitivity was, respectively, 71%, 91% and 83%. WMA were observed after exercise in 9/17 (53%) pts without WMA at rest. 2D Echo obtained after bicycle exercise performed in the supine position is a feasible, sensitive and specific technique to detect CAD.

[Spontaneous echocontrastography. Analysis of 50 cases, review of the literature and a proposal for its classification]. / Ecocontrastografia spontanea. Analisi di 50 casi, revisione della letteratura e proposta di classificazione.

Spontaneous echocontrastographic effect (SEE) is sometimes detected in cardiac chambers. In order to propose a classification of the phenomenon we reviewed our series of 50 patients with SEE. We detected three type of SEE: type I, II, III. Type I was characterized by the presence of low amplitude echoes with slow and irregular motion in a cardiac chamber, in some cases the cloud of echoes had not defined borders (type IA), in other cases the cloud had well defined borders and was attached to a mural thrombus (type IB). Type II was characterized by the presence of echoes moving quickly across the mitral valve toward the left ventricle apex. Lastly, type III was characterized by the presence of microbubbles slowly and chaotically moving in right cardiac chambers. Type I SEE was detected only in patients with clinical conditions (mitral stenosis, congestive cardiomyopathies) characterized by slow intracardiac flow; type II was detected in 3 patients with mitral prosthesis, in 3 with constrictive pericarditis and 1 with severe aortic insufficiency. Lastly, type III was detected in 5 patients with tricuspid insufficiency.

Detection of coronary artery disease by two-dimensional echocardiography and transesophageal atrial pacing.

Two-dimensional echocardiography was performed at rest and during rapid transesophageal atrial pacing in 85 patients undergoing coronary arteriography for evaluation of chest pain. Transesophageal atrial pacing was performed with 10 ms pulses of 6 to 27 mA intensity; the rate was progressively increased up to 150 beats/min. Four patients were excluded: two because atrial capture was not achieved and two because of chest discomfort induced during transesophageal atrial pacing. Of the remaining 81 patients, 56 had significant coronary artery disease (greater than or equal to 75% stenosis of at least one major coronary vessel) and 25 had no significant coronary artery disease; 25 of the 56 patients with coronary artery disease had no wall motion abnormalities at rest. The test was considered positive if wall motion abnormalities were detected during pacing. Wall motion abnormalities occurred in 3 of 25 patients without coronary artery disease (specificity 88%) and in 51 of 56 patients with coronary artery disease (sensitivity 91%). Wall motion abnormalities developed in 20 of the 25 patients with coronary artery disease and normal regional wall motion at rest (sensitivity 80%); sensitivity for one, two and three vessel disease was 85% (17 of 20 patients), 94% (15 of 16 patients) and 95% (19 of 20 patients), respectively. In patients without coronary artery disease, wall motion score was 18 at rest and 17.7 +/- 0.9 during pacing (p = NS). In patients with coronary artery disease, wall motion score decreased from 15.2 +/- 3.6 at rest to 11.6 +/- 4.1 during pacing (p less than 0.001). In patients with coronary artery disease and normal regional wall motion at rest, wall motion score decreased from 18 at rest to 14.4 +/- 3.1 during pacing (p less than 0.001). Thus, two-dimensional echocardiography during transesophageal atrial pacing appears both sensitive and specific in detecting patients with coronary artery disease. This new procedure is a feasible and reliable alternative to exercise two-dimensional echocardiography.