Permanent Pacing in a Patient With Fontan Circulation: Use All You Have at Your Discretion.

Patients with Fontan circulation post significant technical challenges at the time of permanent pacemaker implantation, as majority of them are treated with surgically implanted epicardial pacemakers. However, transvenous pacemaker implantation is technically feasible, and the treating physician should be aware of each individual's anatomy and available treatment options.

Idiopathic ventricular fibrillation controlled successfully with phenytoin.

We describe a case of an individual with idiopathic ventricular fibrillation whose arrhythmias were successfully controlled with phenytoin therapy.

Differential entrainment distinguishes atrioventricular nodal reentry tachycardia from atrioventricular reentrant tachycardia.

BACKGROUND: Entrainment from the right ventricular (RV) apex and the base has been used to distinguish atrioventricular reentrant tachycardia (AVRT) from atrioventricular nodal reentry tachycardia (AVNRT). The difference in the entrainment response from the RV apex in comparison with the RV base has not been tested. METHODS: Fifty-nine consecutive patients referred for ablation of supraventricular tachycardia (SVT) were included. Entrainment of SVT was performed from the RV apex and base, pacing at 10-40-ms faster than the tachycardia cycle length. SA interval was calculated from stimulus to earliest atrial electrogram. Ventricle to atrium (VA) interval was measured from the RV electrogram (apex and base) to the earliest atrial electrogram during tachycardia. The SA-VA interval from apex and base was measured and the difference between them was calculated. RESULTS: Thirty-six AVNRT and 23 AVRT patients were enrolled. Mean age was 44 ± 12 years; 52% were male. The [SA-VA]apex-[SA-VA]base was demonstrable in 84.7% of patients and measured -9.4 ± 6.6 in AVNRT and 10 ± 11.3 in AVRT, P < 0.001. The difference was negative for all AVNRT cases and positive for all septal accessory pathways (APs). CONCLUSION: The difference between entrainment from the apex and base is readily performed and is diagnostic for all AVNRTs and septal APs.

The association of atrial tachyarrhythmias with isolated atrial amyloid disease: preliminary observations in autopsied heart specimens.

OBJECTIVE: Isolated atrial amyloidosis (IAA) is associated with atrial tachyarrhythmias. However, only a few studies have appraised atrial tachyarrhythmias and atrial depolarization abnormalities in connection with high-grade IAA. We conducted a collaborative retrospective study to assess this association. METHODS: One hundred consecutive autopsied hearts were studied histologically for IAA. To increase the specificity for atrial depolarization abnormalities in this preliminary study, we excluded those specimens with intermediate amyloid involvement, i.e. IAA grades 1 and 2 (grade 0 = absent or trivial deposits; grade 1 = small deposits; grade 2 = moderate deposits; grade 3 = dense, large deposits). We then screened for baseline, premortem electrocardiograms (ECGs) to assess rhythm. In those with sinus rhythm, the P wave axis, duration, dispersion and terminal force in V1 were determined under magnification. RESULTS: Of the 27 premortem ECGs corresponding to the autopsy specimens with grades 3 (sample) or 0 (controls) IAA, 9 showed sinus rhythm, 13 showed atrial fibrillation, 1 showed atrial flutter and 4 were uninterpretable. Fourteen autopsied hearts (52%) were positive for grade 3 IAA. Ten of those had atrial tachyarrhythmias (9 atrial fibrillation and 1 atrial flutter) compared to 4 of the 13 hearts with grade 0 IAA (72 vs. 31%, respectively; p = 0.03). Although there was excellent interobserver agreement using intraclass correlation coefficients, there were no significant differences in P wave measurements among the small number of patients with sinus rhythm for grade 3 versus grade 0 IAA. CONCLUSION: In a collaborative, preliminary, pilot assessment of autopsied hearts for which premortem ECGs were necessarily screened retrospectively, significantly more hearts with high-grade IAA were associated with atrial tachyarrhythmias compared to those with low-grade IAA. A larger study with an appropriately matched autopsy control group is needed to confirm these and previous observations.

Is there a role for statins in atrial fibrillation?

3-Hydroxy-3-methyl-glutaryl-CoA reductase inhibitors (statins) are some of the most commonly prescribed drugs in the world. While lipid modification remains the primary function of statins, there has been increasing interest in its potential pleiotropic effects, particularly as an anti-inflammatory agent in its role as an antiarrhythmic. Atrial fibrillation (AF) is the most common arrhythmia encountered in clinical practice and carries with it a significant burden in both morbidity and mortality. Treatment for AF currently involves either rate or rhythm control where both have demonstrable associated risks. Rate control necessitates anticoagulation, which can cause life-threatening bleeding, while rhythm control has a poor side-effect profile that may lead to greater mortality and may not completely eliminate the need for anticoagulation. Considering this pressing need for novel therapeutic interventions in AF, this long overdue systematic review explores the potential role of statins in the treatment and prevention of AF. Physicians, especially cardiologists, need to be aware of the host of currently available literature and, more importantly, need to be stimulated to generate discussion and formulate studies that will help debate the issues under the most erudite standards.

Relation of recurrence of atrial fibrillation after non-ST-elevation acute myocardial infarction to left atrial abnormality.

Atrial fibrillation (AF) is common during the course of acute myocardial infarction and is associated with left atrial (LA) dilatation. However, the role of LA depolarization abnormality on the electrocardiogram (ECG) in the setting of LA dilatation was not studied in this context. Patients admitted with non-ST-segment elevation myocardial infarction (NSTEMI) who developed new-onset AF (International Classification of Diseases, Ninth Revision code 427.31) were prospectively identified. Baseline ECGs and echocardiograms before the admission event were reviewed. Follow-up was directed toward pertinent cardiovascular events, atrial tachyarrhythmias, and death as end points. Of 101 patients with NSTEMI who had new-onset AF, 88 had current echocardiograms and 69 had LA dilatation (78%). Total follow-up was 24 months (mean 21.4). Prolonged P-wave duration (> or =110 ms) and decreased left ventricular fractional shortening were most significant in those with LA dilatation and were independently associated with AF. In those with LA dilatation, the prevalence of such abnormal atrial depolarization on ECGs was 56%. AF (43% vs 15%; p = 0.03) and heart failure (63% vs 35%; p = 0.03) occurred more often in this subset, but there was no difference in mortality. However, the overall prevalence of late cardiovascular complications in this subset was higher (71% vs 45%; p = 0.02) compared with that of immediate complications (20% vs 26%; p = 0.60). In conclusion, there is higher recurrence of AF in patients with NSTEMI who have a combination of electrocardiographic and echocardiographic LA abnormalities compared with those without.

Differences in treadmill exercise tolerance parameters between patients with partial and advanced interatrial depolarization abnormality.

Advanced interatrial block (aIAB) is considerably much less common than partial interatrial block (pIAB), occuring in <2% of the elderly hospitalized population. Less is, therefore, known of the true clinical burden of aIAB, particularly in relation to graded exercise. Therefore, 12 patients with aIAB and 30 patients with pIAB who performed a baseline exercise tolerance test and had a repeat test performed > or = 2 years later were included in the study. Exercise tolerance, echocardiographic findings, and major adverse cardiovascular events were compared. Left atrial size progressed at a significantly faster rate in those with aIAB. In addition, Duke Prognostic Treadmill scores were significantly lower on follow-up in those patients with aIAB. Overall, patients with aIAB had significantly greater left atrial size (48.3 +/- 9 vs 42.8 +/- 4 mm, p < 0.01) and significantly lower Duke Prognostic Treadmill scores than those with pIAB (-0.2 +/- 5 vs 4.1 +/- 4, p < 0.05). There were, however, no significant differences in the occurence of major adverse cardiovascular events. In conclusion, left atrial size progressed at a significantly faster rate but Duke Prognostic Treadmill scores were significantly lower in those with aIAB compared with patients with pIAB after > or = 2 years of follow-up. Further study is required to determine whether patients with aIAB require follow-up echocardiography and/or exercise tolerance tests for optimal risk stratification.

Can U waves be "notched"?

Abnormal U waves (unduly larger or misshapen) are associated with several conditions such as hypokalemia, arrhythmias, cardiac ischemia, ventricular hypertrophy, and hypertension. Abnormal U waves have also been linked to certain cardiac medications, predominantly antiarrhythmics. However, mechanisms of U-wave-abnormality remains debated and perhaps elusive with the true U-wave relationship to T waves still being investigated. While there have indeed been reports of bifid ("notched") T waves, such comparably described U waves have escaped us thus far. We present a case of possibly bifid U waves that persisted over the course of 10 years in the setting of repeated negative Holter monitor findings and clinical absence of atrial tachyarrhythmias. We take this opportunity to briefly discuss common causes of "normal" and abnormal U waves.

Spontaneous alternans in Brugada ST-segment morphology within minutes.

Brugada syndrome is an inherited, life-threatening, cardiac channelopathy where the electrocardiogram (ECG) characteristically depicts a classic pattern of complete or incomplete right bundle-branch block with ST-segment elevation in the right precordial leads V(1) to V(3). These, almost inalienable, ECG patterns may be dynamic, where changes may resolve to baseline or one particular type may evolve into another. Such alternans has been described with fever, electrolyte imbalances, atrial pacing, glucose and/or insulin administration, psychotropic drugs, beta-adrenergic blocker use, class IA and IC antiarrhythmic provocation testing, such as with ajmaline, procainamide, or flecainide, and even large meals, that is, "full stomach sign." However, spontaneous alternans between the different types of Brugada ECG patterns (types) have not been reported within minutes, in the absence of previously described precipitating factors. We present a novel case where classic, type 2, Brugada-like ECG pattern evolved spontaneously to type 1 before returning to type 2 within minutes of presentation.

Successful ablation of idiopathic left ventricular tachycardia in an adult patient during extracorporeal membrane oxygenation treatment.

Idiopathic ventricular tachycardia (VT) is usually a benign arrhythmia with good prognosis that can be managed with antiarrhythmic agents and is often cured using ablation. There is, however, a malignant potential in a subset of patients with idiopathic VT as was the case for our patient whom we discuss in this case report. After a review of the medical literature, and to our knowledge, this is the first case of a successful idiopathic VT ablation in an adult while extracorporeal membrane oxygenation was being used.

Dilated cardiomyopathy: an unexpected complication of rapidly conducted atrial flutter in the Wolff-Parkinson-White syndrome.

This report describes a 34-year-old male with the Wolff-Parkinson-White syndrome who presented with the unusual finding of a tachyarrhythmia-induced cardiomyopathy secondary to atrial flutter with 1:1 conduction through a left-lateral accessory pathway. Catheter ablation of the accessory connection resulted in complete normalization of cardiac function.

Cardiac Outcomes Through Digital Evaluation (CODE) STEMI project: prehospital digitally-assisted reperfusion strategies.

BACKGROUND: Guidelines for reperfusion in ST-elevation myocardial infarction (STEMI) were recently adopted by the Canadian Cardiovascular Society. We have developed a blended model of prehospital thrombolytic (PHL) therapy or primary percutaneous coronary intervention (PPCI) activation, in order to achieve guideline times. METHODS: In our urban centre of 658,700 people, emergency medical services (EMS) were trained to perform and screen electrocardiograms (ECGs) for suspected STEMI. Suspected ECGs were transmitted to a physician's hand-held device. If the physician confirmed the diagnosis they coordinated initiation of either PHL or PPCI. In cases where physicians found the prehospital ECG negative for STEMI (PHENST), patients were transported to the closest emergency room. RESULTS: From July 21, 2008 to July 21, 2010, the Cardiac Outcomes Through Digital Evaluation (CODE) STEMI project received 380 transmitted calls. There were 226 confirmed STEMI by the on-call physician, 158 (70%) received PPCI, 48 (21%) received PHL, and 20 (9%) had angiography but no revascularization. The PPCI, median time from first medical contact to reperfusion was 76 minutes (interquartile range [IQR], 64-93). For PHL, median time from first medical contact to needle was 32 minutes (IQR, 29-39). The overall mortality rate for the STEMI patients was 8% (PHL = 4 [8.3%], PPCI = 8 [5%], medical therapy = 7 [35%]). There were 154 PHENST patients, 44% later diagnosed with acute coronary syndrome. The mortality rate for PHENST was 14%. CONCLUSIONS: Through a model of EMS prehospital ECG interpretation, digital transmission, direct communication with a physician, and rapid coordinated service, we demonstrate that benchmark reperfusion times in STEMI can be achieved.