Rami Rabahieh

Echocardiographic Parameters for Predicting Maintenance of Sinus Rhythm After Internal Atrial Defibrillation

Chronic atrial fibrillation (AF), which is refractory to external electrical direct current shock and/or pharmacologic cardioversion, may be successfully cardioverted using internal atrial defibrillation. To avoid unnecessary procedures, it is important to be able to predict which patients will revert to AF. Thirty-eight patients with chronic AF underwent successful internal atrial defibrillation and were followed for 6 months after restoration of sinus rhythm. Left atrial (LA) diameter, left ventricular ejection fraction, maximum LA appendage area, and peak emptying velocities of the LA appendage were analyzed to determine which of these factors were associated with recurrence of AF. Forty-nine percent of patients had a recurrence of AF within 6 months following internal atrial defibrillation. The preprocedural ejection fraction (mean +/- SD 59 + 14% vs 57 + 13%, p = 0.63), LA diameter (4.2 +/- 0.6 cm vs 4.5 +/- 0.6 cm, p = 0.16), and LA appendage area (5.0 +/- 1.5 cm2 vs 5.8 +/- 1.5 cm2, p = 0.13) did not differ significantly between patients who maintained sinus rhythm and those who had recurrence of AF. Peak emptying velocities of the LA appendage before cardioversion were significantly lower in patients with recurrence of AF compared with patients who maintained sinus rhythm (0.26 +/- 0.1 m/s vs 0.49 +/- 0.17 m/s, p = 0.001). A peak emptying velocity <0.36 had a sensitivity of 82% and a specificity of 83% for predicting recurrence of AF.

Right atrial appendage thrombosis in atrial fibrillation: its frequency and its clinical predictors

This study assesses the incidence of right atrial (RA) chamber and appendage thrombosis in patients with atrial fibrillation (AF) in relation to RA appendage morphology and function. Transthoracic and multiplane transesophageal echocardiography were performed in 102 patients with AF to assess the incidence of RA and left atrial (LA) thrombi and spontaneous echo contrast. Both right and left ventricular sizes, atrial chamber and appendage sizes and function were measured. Twenty-two patients in sinus rhythm served as the control group (SR). Complete visualization of the RA appendage was feasible in 90 patients with AF. Patients with AF had lower tricuspid annular excursion (p = 0.008) and larger RA chamber area (p = 0.0001) than patients in SR. In addition, RA appendage areas were larger (p <0.05) and RA ejection fraction and peak emptying velocities (both p <0.0001) were lower in patients with AF patients than in those in SR. Equivalent differences were found for the LA appendage. Six thrombi were found in the RA appendage and 11 thrombi in the LA appendage in AF patients. Spontaneous echo contrast was found in 57% and 66% in the right atrium and in the left atrium, respectively. AF patients with RA appendage thrombi had a larger RA area (p = 0.0001), and lower RA appendage ejection fraction and emptying velocities (both p = 0.0001) than patients without thrombi. Spontaneous echo contrast was detected in all patients with thrombi. Spontaneous echo contrast was the only independent predictor of RA (p = 0.03) and LA appendage thrombosis (p = 0.036). In conclusion, multiplane transesophageal echocardiography allows the assessment of RA appendage morphology and function. RA spontaneous echo contrast is the only independent predictor of RA appendage thrombosis.

Right Atrial Thrombi and Depressed Right Atrial Appendage Function After Cardioversion of Atrial Fibrillation.

Background: It has been shown that cardioversion of atrial fibrillation may result in left atrial chamber and appendage dysfunction and cause new thrombi in the left atrium. The aim of this prospective study was to investigate right atrial appendage function and assess the incidence of new right atrial thrombi after electrical cardioversion. Methods: Transthoracic echocardiography was performed in 25 patients 4 h before and at 24 h and 7 days after electrical cardioversion to determine right and left atrial mechanical function (internal atrial defibrillation, n = 16; external electrical cardioversion, n = 9), as assessed by peak A wave velocities derived from the transtricuspid and transmitral velocity profiles. In addition, transesophageal echocardiography was performed 4 h before and 24 h after cardioversion to evaluate postcardioversion thrombus formation in the right and left atrial chambers and to assess right and left atrial appendage function. The degree of spontaneous echo contrast was noted, and peak emptying velocities of the appendages were measured before and after cardioversion. Results: Peak emptying velocities of both the right atrial appendage (mean ± SD, 0.23 ± 0.1 vs 032 ± 0.11 m/sec; P = 0.02) and the left atrial appendage (0.3 ± 0.15 vs 0.4 ± 0.15 m/sec; P = 0.01) were significantly lower 24 h after cardioversion compared with 4 h before cardioversion, respectively. The degree of spontaneous echo contrast increased in the left atrium after cardioversion from 1.0 ± 1.2 to 1.9 ± 2.1 (P = 0.02), and in the right atrium, it increased from 0.8 ± 1.1 io 1.2 ± 1.1 (P = 0.1) after cardioversion. Peak A wave transtricuspid velocity increased from 0.26 ± 0.05 m/sec at 24 h to 0.38 ± 0.06 m/sec (P = 0.001) after 7 days; respective values for transmitral peak A wave velocity were 0.39 ± 0.15 and 0.54 ± 0.16 m/sec (P = 0.009). No thrombi were found in either the right or left atrium before cardioversion. In two patients, new thrombi in the right atrium were detected 24 h after internal atrial defibrillation. Thrombi were located at the superior rim of the fossa ovalis in both patients with patent foramen ovale. Another patient had developed a thrombus in the left atrial appendage. Conclusions: Electrical cardioversion may not only cause left atrial chamber and appendage dysfunction and left atrial thrombi but also lead to depressed right atrial appendage function and the generation of new thrombi in the body of the right atrium.

Hemodynamic and cardiorespiratory function following internal atrial defibrillation for chronic atrial fibrillation

Internal atrial defibrillation (IAD) is able to restore sinus rhythm in patients with chronic atrial fibrillation (AF) and failed external electrical and/or pharmacologic cardioversion. To assess whether cardiorespiratory and hemodynamic function improve after IAD, 35 patients were prospectively investigated during constant workload exercise by spiroergometry and Doppler echocardiography before IAD, and 1 day and 1 month after IAD. Oxygen uptake kinetics, ventilation, left atrial mechanical function, and pulmonary artery pressure were determined simultaneously at rest and during steady state. During the serial follow-up, 20 patients maintained sinus rhythm. The time interval for achieving the steady state (146 +/- 53 vs 132 +/- 42 seconds; p = 0.5) and the oxygen deficit (645 +/- 190 vs 670 +/- 174 ml; p = 0.7) were not different before and 1 day after IAD, but decreased significantly after 1 month (98 +/- 16 seconds, p = 0.01 and 487 +/- 72 ml, p = 0.02). Exercise pulmonary artery systolic pressures were 38 +/- 13 mm Hg before IAD, increased significantly to 46 +/- 11 mm Hg on day 1 (p = 0.03), and decreased below baseline values at 1 month to 31 +/- 12 mm Hg (p = 0.07). Peak A-wave velocities increased from 0.51 +/- 0.1 m/s after 1 day to 0.67 +/- 0.2 m/s after 1 month (p = 0.03). Restoration of sinus rhythm in patients with AF resistant to external electrical and/or pharmacologic cardioversion improves hemodynamic and cardiorespiratory function at daily activity exercise levels.

Transesophageal Echocardiographic Imaging of De Novo Thrombus Formation After Successful External Electrical Cardioversion of Atrial Fibrillation

One of the major risks of cardioversion of atrial ~brillation is the occurrence of thromboembolism [1]. Thromboembolism has been attributed to the dislodgement of preexisting left atrial thrombi, which are propelled into the systemic circulation with the restoration of sinus rhythm. However, recently it has been shown that thromboembolism may even occur in patients who did not have thrombi before cardioversion [2]. In order to explain this phenomenon, investigators performed transesophageal echocardiography during and after electrical cardioversion. They found that cardioversion itself may create a thrombogenic mileu in the left atrium, which potentially may cause the development of new thrombi in the left atrial chamber and appendage [3–5]. In this case study, we report on a patient who developed a new thrombus after external electrical cardioversion and discuss the clinical implications of our ~ndings.

The clinical impact of computer assisted evaluation of ultrasonic tissue and flow data

Based on a complete digital transfer of echocardiographic and Doppler-echocardiographic recordings to an external computer, physicians can access the digitalized raw data during any investigation. Three practical examples demonstrated the present clinical impact and future aspects of the new technical possibilties. In the first simple application, the velocities depicted along a color M-Mode line are averaged. The resulting velocity traces recorded within the mitral valve inflow regions demonstrated a better reproducibility than regular Doppler single-gate registrations did. In the second example, we analyzed the two-dimensional real-time Doppler recordings in patients with mitral regurgitation. Special attention was given to the signal amplitude which the computer directly extracted. The intensity flow mapping technique revealed that the highest reflected Doppler intensities were registered in the central parts of the regurgitant jets, while, in general, the parajet regions represented low intensity fields. Based on this observation, one can conclude that measurements of any color coded two-dimensional parameter will achieve the highest accuracy within the central part of the jet. The third example of computer evaluated echocardiographic data presents a newly developed system for real-time three-dimensional reconstruction of left ventricular endocardial casts. Further evaluating procedures are budding in this promising new field of echocardiography which primarily applies automatic endocardial contour definition.