Abnormal Nocturnal Heart Rate Variability and QT Dynamics in Patients with Brugada Syndrome

Background: In Brugada syndrome (BSY), most of the ventricular arrhythmic events are nocturnal, suggesting an influence of the autonomic nervous system.
Methods: In 46 patients (mean age = 41 ± 14 years, 43 men) with electrocardiograms (ECG) consistent with BSY and structurally normal hearts, we measured heart rate variability (HRV) and QT dynamics (QT/RR slopes) on 24-hour ambulatory ECG. Type 1 BSY-ECG was spontaneous in 23 (50%) and induced in 23 patients.
Results: History of syncope was present in 23 patients (50%). Programmed ventricular stimulation induced ventricular tachyarrhythmias (VTA) in 13 patients (28%). A single patient developed ventricular tachycardia during a mean follow-up of 34 months. Compared to a control group matched for age and sex, HRV was decreased over 24 hours and during nighttime in patients with BSY (SDNN 122 ± 44 vs 93 ± 36 ms, P = 0.0008 and SDANN 88 ± 39 vs 54 ± 24 ms, P < 0.0001). QTend /RR slopes were decreased over 24 hours in patients with BSY (0.159 ± 0.05 vs 0.127 ± 0.05, P = 0.003) and particularly at night (0.123 ± 0.04 vs 0.089 ± 0.04, P = 0.0001). QTend /RR slopes were significantly decreased during nighttime in patients with spontaneous versus provoked BSY-ECG patterns. By contrast, HRV and QT/RR slopes were similar in symptomatic and asymptomatic patients, whether VTA were induced or not.
Conclusions: Patients with a BSY-ECG pattern had lower HRV and QT/RR slopes than control subjects during nighttime. High-risk patients with spontaneous BSY-ECG patterns had the lowest nocturnal QTend/RR slopes. These unique repolarization dynamics might be related to the frequent nocturnal occurrence of VTA in BSY.     

Long-Term Outcomes After Cryoablation for Ventricular Tachycardia During Surgical Treatment of Anterior Ventricular Aneurysms

Intraoperative map-guided procedures have been widely advocated as the best surgical strategy for the treatment of ventricular tachycardia (VT), though favorable results have been reported with subendocardial resection without mapping. This study examined the very long-term results of encircling cryoablation without mapping during surgery for anterior left ventricular aneurysm complicated by VT. Between 1985 and 2003, this procedure was performed in 52 patients, 7 of whom (13.7%) were operated within 1 month of anterior myocardial infarction. Their mean age was 64.4 ± 8.3 years and mean left ventricular ejection fraction was 31.7%± 9.5%. The overall hospital mortality was 1.9%. At 14 years, 86% of patients (95% CI: 75.4–96.6) were free from VT or sudden death. An implantable defibrillator was implanted in five patients (9.6%) during follow-up. The 14-year overall survival was 51.4% (95% CI: 33.8–72.4), and two patients (3.8%) underwent cardiac transplantation during follow-up. The main cause of late death was congestive heart failure in eight patients (40.0%). Favorable long-term results can be achieved with encircling cryoablation without mapping in patients undergoing surgery for anterior left ventricular aneurysm complicated by VT.     

Transient ST Elevation After Ketamine Intoxication: A New Cause of Acquired Brugada ECG Pattern

Brugada Syndrome and Ketamine Overdose. A 31‐year‐old man was referred for ketamine overdose. He presented initially with transient major Brugada ECG pattern. Complete investigation led to the diagnosis of slowly resolvent toxic myocarditis. Brugada‐like ECG was suspected to be caused by the ketamine intoxication in this case. (J Cardiovasc Electrophysiol, Vol. 22, pp. 91‐94, January 2011)     

Sudden Death as a Presenting Symptom of Hypertrophic Cardiomyopathy: Treatment with an Implantable Cardioverter Defibrillator

Aborted sudden death as the presenting manifestation of hypertrophic Cardiomyopathy in a 14-year-old child is reported. Documented ventricular fibrillation was the cause of cardiac arrest. No ventricular arrhythmia was induced during programmed electrical stimulation. An implantable cardioverter-defibrillator was indicated. As the patient had a family history of myocardial disease, he had undergone a cardiovascular evaluation 4 years before the major event, and was found normal. It is suggested that normal physical examination, ECG, echocardiogram should not rule out the diagnosis of hypertrophic Cardiomyopathy when a family history is present. Left ventricular hypertrophy may develop during childhood in patients with hypertrophic Cardiomyopathy.     

Cardiac Surgery in Patients with Human Immunodeficiency Virus Infection: Indications and Results

Ten patients with human immunodeficiency virus (HIV) infections underwent cardiac surgery using cardiopulmonary bypass. All were in Centers for Disease Control (CDC) group II. The cardiac involvement was either urgent or severely symptomatic in all cases. One patient died due to acquired immunodeficiency syndrome (AIDS) unrelated cause. No complications were encountered in this series. Eight of the nine survivors were available for follow-up. Three of these eight patients progressed to AIDS (CDC group IV) and subsequently died. Five patients are alive and in CDC group II. Prognosis of the HIV infection and the natural history of the cardiac disease are the two main elements to be considered whenever cardiac surgery is required.     

Autonomic Influences in Atrial Tachyarrhythmias

Atrial Tachyarrhythmias. The electrophysiologic characteristics of atrial cells (action potential duration and refractoriness, conduction speed) are modulated differently by vagal and sympathetic influences. The former tend to favor macroreentry phenomena, whereas the latter favor abnormal automaticity and triggered activity. In normal hearts, vagal influences are predominant, thus explaining why the Clinical pattern of vagally mediated paroxysmal atrial fibrillation is preferentially observed in the absence of detectable heart disease, in young male adults, with an ECG pattern of common flutter alternating with fibrillation. Sympathetically mediated atrial fibrillation is observed in the presence of any heart disease, the first effect of which is to provoke a vagal withdrawal. The clinical history is a reliable guide for determining which type of physiologic autonomic predominance contributes to destabilization of the arrhythmogenic substrate, but observing the behavior of sinus rate variability just preceding the onset of the arrhythmia only permits documentation of the mechanism. The role of autonomic influences should be taken into consideration every time conventional antiarrhythmic treatment is insufficient. Beta blockers as well as digitalis may be either beneficial or detrimental, depending on the causal mechanism, so the choice of their use as a single or a combined therapy should be appropriate.     

The Total Artificial Heart: Indications and Preliminary Results

The development of the total artificial heart (TAH) has reached a level where it is now available for clinical applications. The TAH has demonstrated distinct advantages over other forms of mechanical circulatory assistance. As of December 1, 50 TAHs have been implanted: 5 as permanent devices, and 45 as a temporary mechanical bridge to cardiac transplantation. The use of the TAH has increased in the last several months, leading to a growing interest in defining the indications and contraindications to its use. End-stage cardiomyopathy (either idiopathic, ischemic, viral, or postpartum) has been the underlying disease in 80% of the TAH procedures to date. The TAH has also been applied in 5 cases of acute cardiac graft rejection, 2 cases of congenital heart diseases, and in one case after acute myocardial infarction. The indications for the use of the TAH in these and other potential patient groups is discussed in light of the current clinical results.     

Catheter Ablation of Left Parietal Accessory Pathways

Fifty-one patients with a left parietal pathway and drug refractory tachycardia underwent transcatheler ablation of their accessory pathway. Three had single concealed pathways, two had multiple pathways, and the remaining 46 had the Wolff-Parkinson-While syndrome. Two patients were resuscitated from a cardiac arrest related to a ventricular fibrillation. A multipolar (quadri-, hexa-, or octopolar) electrode catheter was positioned within the coronary sinus in order to localize the pathway accurately. An ablation catheter was then introduced either through a patent foramen ovale (11 patients), by transseptal catheterization (14 patients) or a retrograde arterial catheterization (26 patients). The mitral annulus was mapped with this catheter during orthodromic tachycardia in order to record ventriculoatrial (VA) time as short as (or even shorter than) that recorded in the coronary sinus. The VA time in our series was 82 ± 13 msec. Two 160-joule cathodal shocks were delivered at this site and eventually repeated according to the results (73 sessions/51 patients). The mean cumulative energy was 650 ± 205 joules. No significant side effects occurred except one case of a right coronary artery spasm leading to inferior wall infarction. During follow-up of 2–49 months, all but two patients were free of tachycardia. Twelve patients were reassessed 4 to 8 months after the procedure: conduction over the pathway was absent, and no vascular damage was noticed. Catheter ablation of left parietal accessory pathways is both effective and safe. Ablation by retrograde arterial catheterization was as efficient as the tranxseptal approach. This method is an attractive alternative to surgery.