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D M Todd

Publications and source records attributed to D M Todd.

9 recordsLinked to original sources
PubMed2006

Modern management of arrhythmias.

The specialist management of arrhythmias has changed significantly over the past decade. This article outlines current management strategies for atrial flutter and atrial fibrillation, with particular emphasis on curative strategies with catheter ablation and the recent data on rhythm compared with rate control strategies. The expanding role of catheter ablation in the treatment of a wide variety of supraventricular and ventricular arrhythmias is discussed. The current evidence for implantable cardioverter defibrillators in the prevention of sudden cardiac death is summarised. The article also highlights the increasing recognition of a number of inherited syndromes that predispose to sudden cardiac death (for example, Brugada and long QT syndromes).

Anti-Arrhythmia Agents↗
PubMed2001

Multicentre, prospective, randomized trial of 4 vs. 6 French catheters in 410 patients undergoing coronary angiography.

The aim of this study was to assess the quality of angiograms obtained using 4 Fr catheters compared with 6 Fr catheters, the ease of use of the 4 Fr catheters, and the safety of patient mobilization 1 hr following 4 Fr angiography. Details of catheter performance and procedural details were recorded at the time of the angiogram. The angiographic images were scored on the quality and completeness of vessel opacification throughout systole and diastole. A total of 410 patients were recruited. There was no difference between 4 and 6 Fr for procedural variables. All angiograms were considered to be of diagnostic quality. The angiographic scores for the right coronary artery and left ventricular injections were no different between 4 and 6 Fr. However, the angiographic scores for the left anterior descending and circumflex arteries were lower with 4 than with 6 Fr (both P < 0.05). Patients who had 4 Fr angiography mobilized safely at 1 hr and reported significantly less discomfort and bruising than 6 Fr patients. Good-quality diagnostic coronary angiograms can be achieved using 4 Fr catheters with the advantage of earlier postprocedural mobilization and reduced discomfort and bruising for the patient.

Aged↗
PubMed2001

Role of dispersion of atrial refractoriness in the recurrence of clinical atrial fibrillation; a manifestation of atrial electrical remodelling in humans?

AIMS: The mechanism of atrial fibrillation recurrence following cardioversion is unknown, although experimental studies have indicated that changes in dispersion of atrial refractoriness may play a role. The aims of this study were to assess (1) if dispersion of atrial refractoriness is relevant to atrial fibrillation recurrence and (2) if dispersion of refractoriness is part of the atrial electrical remodelling process in humans. METHODS AND RESULTS: Thirty-seven consecutive patients underwent internal cardioversion (CV1) of persistent atrial fibrillation. Patients were monitored by daily transtelephonic recordings following discharge and if there was spontaneous atrial fibrillation recurrence they were rapidly admitted for repeat cardioversion (CV2). We used the 5th percentile of 100 consecutive atrial fibrillation cycle lengths (AFCL(P5)) and the atrial effective refractory period (AERP) as measures of atrial refractoriness at four different atrial sites. Dispersion of AFCL(P5)at CV1 was significantly higher in those who had subsequent recurrence of atrial fibrillation than in those who remained in sinus rhythm for at least 1 month after cardioversion (35+/-17 ms vs 9+/-13 ms;P<0.02). Dispersion of AFCL(P5)measured at CV2 was significantly lower than that measured in the same patients at CV1 (19+/-8 ms vs 35+/-11 ms;P=0.02). i.e. dispersion of AFCL(P5)had reduced following a period of sinus rhythm. In contrast, there was no difference in dispersion of AERP between the recurrers and non-recurrers. Dispersion of AERP between CV1 and CV2 did not change following a period of sinus rhythm. CONCLUSION: Dispersion of AFCL is relevant to atrial fibrillation recurrence and may represent a manifestation of atrial electrical remodelling in humans. Treatment directed at AFCL dispersion may be useful in the suppression of atrial fibrillation recurrence following cardioversion.

Adult↗
PubMed2000

Reversal of atrial electrical remodeling after cardioversion of persistent atrial fibrillation in humans.

BACKGROUND: Although atrial electrical remodeling has been studied extensively in animal models, the reversibility of this phenomenon after termination of clinical atrial fibrillation (AF) has not been demonstrated. We aimed to examine this important question of reversibility by using AF cycle length (AFCL) and coupling intervals of atrial premature beats after cardioversion as measures of atrial refractoriness. METHODS AND RESULTS: We measured AFCL at the right atrial appendage and distal coronary sinus before attempting internal cardioversion in 39 patients with persistent AF. Patients were monitored by daily transtelephonic recordings after discharge and admitted rapidly for repeat internal cardioversion if there was spontaneous AF recurrence. Measurements of AFCL were repeated immediately before repeat cardioversions in the 17 patients who had recurrence of AF. There was an increase in AFCL from the initial cardioversion to that measured at the time of first AF recurrence at both the right atrial appendage (161+/-22 vs 167+/-26 ms, P=0.05) and distal coronary sinus (162+/-20 vs 168+/-22 ms, P=0.01) sites. The magnitude of increase in AFCL was positively correlated with duration of sinus rhythm before AF recurrence (r=0.524, P=0.001). Other measures of refractoriness (shortest coupling interval of atrial premature beats and directly measured refractory periods after cardioversion) also increased from initial to subsequent cardioversions. CONCLUSIONS: These findings demonstrate that changes in atrial electrophysiology associated with chronic AF in humans are reversible after cardioversion and that the extent of this reversal is dependent on the duration of sinus rhythm after cardioversion.

Adult↗
PubMed2000

Prevalence and significance of focal sources of atrial arrhythmia in patients undergoing cardioversion of persistent atrial fibrillation.

INTRODUCTION: Recent reports have high-lighted the importance of focal atrial arrhythmias as a curable cause for a group of patients with frequently recurrent paroxysmal atrial fibrillation (AF). The importance of this arrhythmia mechanism in the general population of patients with persistent AF is unknown. METHODS AND RESULTS: After successful internal cardioversion of 50 consecutive patients with persistent AF (mean age 60 years, mean duration of AF 26 months), endocardial activity in the immediate postcardioversion period was analyzed for the presence of focal atrial activity. Postcardioversion atrial arrhythmias were considered to be focal if there was evidence of a localized source of repetitive early atrial activation, either in the form of (1) self-terminating monomorphic atrial tachycardia (at least five beats) or (2) recurrences of AF with an initial atrial activation sequence (first five beats) that was both monomorphic and reproducible with repeated recurrences. Evidence for a focal atrial arrhythmia was present in 20 of the total group of 50 patients (40%). Multivariate analysis of clinical characteristics revealed the diagnosis of lone AF as the only independent predictor of a focal source of AF (P = 0.028). Thirty-nine patients were discharged from hospital in sinus rhythm. At 1-month follow-up, 25 (64%) of these 39 patients had suffered AF recurrence. The only significant predictor of AF recurrence was evidence of a focal source of atrial arrhythmia immediately after cardioversion, with a relative risk of 1.73 (range 1.1 to 2.7; P = 0.015). CONCLUSION: Focal atrial arrhythmias are common in patients presenting with "idiopathic" persistent AF, suggesting a possible causative role in the generation of this common arrhythmia.

Aged↗