Restoration of sinus rhythm is not always followed by immediate return of effective atrial contraction. Left atrial mechanical function can be assessed by Doppler echocardiography; in the present study we measured the atrial ejection force, which is a noninvasive Doppler-derived parameter that measures the strength of atrial contraction. The aim of the present study was to evaluate the influence of clinical and echocardiographic parameters: duration and cause of atrial fibrillation, different modality of cardioversion, and left atrial size with respect to the delay in the return of effective atrial contraction after cardioversion. Seventy patients were randomly chosen to undergo cardioversion by either direct current shock or intravenously administered procainamide hydrochloride. The 52 patients who had sinus rhythm restored underwent a complete Doppler echocardiographic examination 1 h after the restoration of sinus rhythm and after 1 day, 7 days, and 1 month. The relation between clinical variables and atrial ejection force was tested. Atrial ejection force was greater immediately and 24 h after cardioversion in patients who underwent pharmacologic therapy compared to patients treated with direct current shock (11.3+/-3 versus 5+/-2.9 dynes; P<0.001). In both groups atrial ejection force increased over time. The mode of cardioversion was significantly associated with recovery of left atrial mechanical function by day 1 in univariate and multivariate analysis (odds ratio, 0.14; 95% confidence interval, 0.02-1.2). The other variable associated with the delay in the recovery of atrial function was a dilated left atrium (odds ratio, 0.16; 95% confidence interval, 0.12-1.6). Atrial ejection force is a noninvasive parameter that can be easily measured after cardioversion and gives accurate information about the recovery of left atrial mechanical function. The recovery of left atrial function was influenced by the mode of cardioversion and left atrial size.
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[Show abstract][Hide abstract] ABSTRACT: Abstract: Atrial fibrillation (AF) is considered the most common arrhythmia affecting exercise performance in horses. Quinidine is an effective therapy for conversion of AF to sinus rhythm, but treatment is associated with a number of adverse clinical effects. Furthermore, residual electrical and mechanical abnormalities of the equine atria may account for the recurrence of AF following successful therapy. Relative to these issues, we sought to better understand the physiology of the in vivo equine atria and the associated sinoatrial and atrioventricular (AV) nodal tissues. In treating horses with AF using the drug quinidine, a common adverse effect is marked acceleration of the ventricular response rate prompting early discontinuation of treatment. Diltiazem effectively controls ventricular response to AF in other species, but has not been evaluated in horses. In our first series of experiments we studied the pharmacodynamic and pharmacokinetic effects of the calcium channel blocker diltiazem on the cardiovascular system in healthy horses in sinus rhythm. To further support these studies we characterized the clinical electrophysiology of the normal equine atria and then quantified the electrophysiologic effects of quinidine and diltiazem in a pacing model of atrial tachycardia. Based on our studies demonstrating inhibitory effects on AV nodal conduction, diltiazem is likely to be useful for ventricular rate control in horses with naturally occurring AF undergoing quinidine treatment. Diltiazem appeared relatively safe in healthy horses, but dosage may be limited by hypotension from vasodilatation and direct suppression of sinus node discharge. In our last two studies, we established echocardiographic techniques to assess mechanical function of the equine left atrium noninvasively and applied these methods to a subset of horses recently converted from AF to normal sinus rhythm. Our preliminary guidelines for echocardiographic assessment of LA size and mechanical function will likely be useful to study LA function in horses with cardiac disease. Specifically, we were able to show that LA mechanical function in horses can be significantly depressed after successful conversion of AF to sinus rhythm. The clinical relevance of these findings will have to be established in future investigations. Thesis (Ph. D.)--Ohio State University, 2006. System requirements: World Wide Web browser.
[Show abstract][Hide abstract] ABSTRACT: Assess the value of peak atrial systolic mitral annular velocity (Aann) measured by Doppler tissue echocardiography to quantify left atrial systolic function.
We studied a total of 61 adults; 10 subjects without history of heart disease and 51 patients with a history of atrial fibrillation or undergoing evaluation for left ventricular systolic or diastolic dysfunction. Aann was obtained by averaging peak atrial systolic mitral annular velocities from the septal, lateral, anterior, and inferior annulus. Left atrial fractional area change (FAC) and fractional volume change (FVC) during atrial systole were calculated. The correlation between peak atrial systolic mitral annular velocity (Aann) and left atrial systolic FAC and FVC was determined.
Mean FAC and FVC were 27 +/- 12 and 40 +/- 14%, respectively; mean Aann was 11.2 +/- 3.2 cm/s. Linear regression analysis showed correlation between Aann and FAC (r = 0.71; p<0.001) and between Aann and FVC (r = 0.74; p<0.001).
Peak systolic mitral annular velocity correlates well with left atrial systolic FAC and FVC, thus providing an easy means to assess left atrial systolic function.
Preview · Article · Jan 2004 · European Heart Journal – Cardiovascular Imaging
[Show abstract][Hide abstract] ABSTRACT: Clinical studies have shown that transthoracic cardioversion of atrial fibrillation is dependent on achieving adequate current flow to the heart, which is dependent on transthoracic impedance. When multiple standard cardioversion fails to restore sinus rhythm in patients with atrial fibrillation the double sequential transthoracic shock may be an alternative.
Twenty one consecutive patients with paroxysmal or persistent atrial fibrillation refractory to at least two initial high energy 360 J or 200-300 and 360 J monophasic shocks underwent double sequential shocks with 720 J by means two defibrillators. Mean age was 64 +/- 11 years and mean weight 97 +/- 19 kg (range, 49 to 112). Duration of atrial fibrillation was present < or = 3 months in 76%. Arterial hypertension was present in 38% and lone atrial fibrillation in 33%. Mean left atrial size was 4.5 +/- 0.7 cm (range, 3.5 to 6.0). Sinus rhythm was achieved in 19 (90.4%). Two refractory to biphasic shocks with a median 1,050 J (range, 660 to 1,440 J) without major complications. Multivariate analysis identified duration of atrial fibrillation, > 90 days (RR 0.96, CI 0.95-0.98 p = 0.02) and body weight, 101 +/- 11 kg (RR 0.64, CI 0.46-0.90 p = 0.01) variables independently associated with cardioversion unsuccessful. Patient weight, p = 0.002 was the univariate predictor of unsuccessful cardioversion. High energy cardioversion does not cause cardiac damage evidenced from cardiac troponin T estimation.
For refractory atrial fibrillation to conventional cardioversion double sequential transthoracic shocks represents a safe and highly efficacious alternative and may have a general applicability.
No preview · Article · Jul 2005 · Archivos de cardiología de México