Pacing induced long-term atrial fibrillation in horses

Abstract

Patients with non-rheumatic AF (n-335, age-40-85 years. mean 64+/-42 years; Male 188, Female 147, ware followed up for a mean period of 38±8 months. Palpitation (90%), effort intolerance (82%), angina (60%), heart failure (28%), stroke (15%) and peripheral embolism (5%) were the presenting features. IHD was the commonest aetiology (52%) followed by hypertension (28%), cardiomyopathy (12%), thyrotoxicosis (5%) and lone AF (3%). Age • 65 years, hypertension, transient ischaemtc attacks, diabetes mellitus constituted high dsk group. Chronic AF (54%) was more evident than paroxysmal (24%) and persistent (22%) types Patients with left atrial thrombus (42%) were placed on oral anticoagulants. Incidence of stroke was 0.5% in the anticoagulated groups vs. 15% in controls (p < 0.0001). DC cardiover sion was effective in restoration of sinus rhythm (SR) in 70% cases but maintenance of SR required antiarrhythmic drugs. On average followup of 38+8 months, amiodarone (72%) was found to be superior to quinidine (48%) (p < 0.0001) in relation to maintenance of SR; next to it were digoxin (42%), [(]-blockers (35%), calcium channel blockers (28%). Overall mortality was 4% 40 patients were refractory to drug therapy, 10 of them underwent pacing, 10 underw~ent ablation followed by permanent pacing (DDDR) with mode switching. 70% patients with pacing +/-RF ablation remained symptom-tree and maintained SR for 14+_2 months. In conclusion pacing arm RF ablation in selected cases is superior to pharmacological treatment in symptomatic relief but not in maintenance of SR Drug therapy is the mainstay of treatment for maintenance of SR Aims: Identification of patients at dsk for paroxysmal atdal fibrillation during sinus rhythm has been demonstrated using P wave signal averaged electrocardiography. The predication of PAF however has not been possible due to the presence of Premature Atdal Contraction. The purpose of this study was to test a new computer interface based on a mathematical predictor, for the use of P-Wave SAECG. Methods: An 88 patient (59 M, 59+10) database with at least on e documented episode of PAF, P wave duration on the SAECG, the left atdal diameter and the patient age were collected 24 hours from the last PAF episode. A monthly follow up was performed (3months/pts) for identifying patients with (Group 1, 32 patients) and without (Group 2, 56 patient) PAF recurrence, in order to defne the arrhythmic risk predictor value of P wave duration SAECG. Results:The results were entered via the compute interface with results as shown:Group 1 Group 2 P value Left Atrial diameter (cm) 3.8+5.6 3.7+5.3 0.977 Age (year) 57+11 59+11 0.563 SAECG P wave duration ms 137+14 125+10 0.005 In the discrimination of two groups using the automated predictor , a P wave duration (filtered) > 130 ms showed 73% sensitivity, 76% specifity, 51% positive and 91% negative predictive value. Concluaion: The results indicate the accuracy an automated predictor ol the P wave signal averaged SAECG in identifying patients at risk for the recurrence of atdal...

Effects of an adapted intravenous amiodarone treatment protocol in horses with atrial fibrillation

“…Many factors, including myocardial ultrastructure, AF duration, atrial size and electrophysiological properties might influence the success rate of pharmacological treatment. Long AF duration, large atrial size and short AFCL are all factors leading to increased AF stability (Wijffels et al 1995;van Loon et al 2000). All these factors could have been related to failure of treatment in these 3 horses.…”

“…These animals have a good prognosis for cardioversion and generally return to their previous level of athletic performance after successful treatment. However, when AF persists for >3-6 months or when atrial dilatation is present because of mitral valve regurgitation or AF per se, treatment becomes more difficult and AF recurrence is more common (Reef et al 1988;van Loon et al 2001).…”

Pharmacokinetics and electrophysiological effects of sotalol hydrochloride in horses

“…ERP measurements were performed at twice baseline pacing h threshold at 0.5 ms pulse duration [11]. ERP measurements were performed at twice baseline pacing h threshold at 0.5 ms pulse duration [11].…”

“…Under ultrasound guidance, a contact electrode MAP catheter g was inserted through the right jugular vein into the right atrium and right ventricle. ERP measurements were performed at twice baseline pacing h threshold at 0.5 ms pulse duration [11]. ERP was measured by delivering 10 basic stimuli (S1) with a fixed pacing interval (S1-S1) followed by an extra stimulus (S2) with a coupling interval below the expected refractory period.…”

“…The S1-S2 coupling interval was then increased with 8 ms increments until capture of the extra stimulus occurred. ERP was defined as the longest S1-S2 interval failing to elicit a new action potential [11][12][13]. Five consecutive ERP measurements were recorded at 1000 (63 beats/min) and 600 ms (100 beats/min) basic pacing cycle length.…”