Profound hypothermia mimicking a Brugada type ECG

Brugada phenocopy associated with diabetic ketoacidosis in two pediatric patients

Two patients without cardiac history demonstrated type 1 Brugada pattern during hospitalization for diabetic ketoacidosis (DKA). Both patients had normalization of their ECGs after treatment of marked electrolyte abnormalities and metabolic acidosis. In this report, we describe two cases of Brugada phenocopy associated with DKA in children.

Electrocardiographic Manifestations in three Psychiatric patients with Hypothermia - Case Report

Hypothermia occurs when the core body temperature falls below 35°C, which, in severe cases, can lead to electrocardiographic changes. Several conditions that occur in the psychiatric population increase the risk of hypothermia. This risk can be further increased by the use of several classes of medications such as antipsychotics, beta-adrenergic antagonists and benzodiazepines. We report on three psychiatric patients who were admitted for hypothermia and developed electrocardiographic manifestations (sinus bradycardia, QT prolongation and Osborn waves), which completely resolved after treatment.

Electrocardiographic changes in hypothermia: a review

Hypothermia is a common environmental emergency encountered by physicians and is associated with a variety of electrocardiographic (ECG) abnormalities. The classic and well-known ECG manifestations of hypothermia include the presence of J (Osborn) waves, interval (PR, QRS, QT) prolongation, and atrial and ventricular arrhythmias. There are less well defined and known ECG signs of hypothermia, which in fact may simulate findings of acute coronary ischemia, Brugada syndrome, or even pericarditis. Although classical ECG changes seen in hypothermia certainly serve as an important clinical clue for prompt identification and management of this easily curable life-threatening entity, physicians should, however, be able to maintain a high suspicion for recognition and differentiation of less common ECG abnormalities encountered in hypothermia. This article aims to provide a detailed review of all the potential ECG abnormalities that may be encountered in accidental and iatrogenic hypothermia.

Brugada phenocopy: new terminology and proposed classification

Brugada syndrome is a channelopathy characterized on ECG by coved ST-segment elevation (≥2 mm) in the right precordial leads and is associated with an increased risk of malignant ventricular arrhythmias. The term Brugada phenocopy is proposed to describe conditions that induce Brugada-like ECG manifestations in patients without true Brugada syndrome. An extensive review of the literature identified case reports that were classified according to their suspected etiological mechanism. Future directions to learn more about these intriguing cases is discussed.

Tombstoning ST-Elevation Myocardial Infarction

Tombstoning ST elevation myocardial infarction can be described as a STEMI characterized by tombstoning ST-segment elevation. This myocardial infarction is associated with extensive myocardial damage, reduced left ventricle function, serious hospital complications and poor prognosis. Tombstoning ECG pattern is a notion beyond morphological difference and is associated with more serious clinical results.Despite the presence of a few reports on tombstoning ST elevation, there is no report which reviews STEMI demonstrating this electrocardiographic pattern.

J wave syndromes

The J wave, also referred to as an Osborn wave, is a deflection immediately following the QRS complex of the surface ECG. When partially buried in the R wave, the J wave appears as J-point elevation or ST-segment elevation. Several lines of evidence have suggested that arrhythmias associated with an early repolarization pattern in the inferior or mid to lateral precordial leads, Brugada syndrome, or arrhythmias associated with hypothermia and the acute phase of ST-segment elevation myocardial infarction are mechanistically linked to abnormalities in the manifestation of the transient outward current (I(to))-mediated J wave. Although Brugada syndrome and early repolarization syndrome differ with respect to the magnitude and lead location of abnormal J-wave manifestation, they can be considered to represent a continuous spectrum of phenotypic expression that we propose be termed J-wave syndromes. This review summarizes our current state of knowledge concerning J-wave syndromes, bridging basic and clinical aspects. We propose to divide early repolarization syndrome into three subtypes: type 1, which displays an early repolarization pattern predominantly in the lateral precordial leads, is prevalent among healthy male athletes and is rarely seen in ventricular fibrillation survivors; type 2, which displays an early repolarization pattern predominantly in the inferior or inferolateral leads, is associated with a higher level of risk; and type 3, which displays an early repolarization pattern globally in the inferior, lateral, and right precordial leads, is associated with the highest level of risk for development of malignant arrhythmias and is often associated with ventricular fibrillation storms.

Anabolic-androgenic steroid dependence? Insights from animals and humans

Anabolic-androgenic steroids (AAS) are drugs of abuse. They are taken in large quantities by athletes and others to increase performance, with negative health consequences. As a result, in 1991 testosterone and related AAS were declared controlled substances. However, the relative abuse and dependence liability of AAS have not been fully characterized. In humans, it is difficult to separate the direct psychoactive effects of AAS from reinforcement due to their systemic anabolic effects. However, using conditioned place preference and self-administration, studies in animals have demonstrated that AAS are reinforcing in a context where athletic performance is irrelevant. Furthermore, AAS share brain sites of action and neurotransmitter systems in common with other drugs of abuse. In particular, recent evidence links AAS with opioids. In humans, AAS abuse is associated with prescription opioid use. In animals, AAS overdose produces symptoms resembling opioid overdose, and AAS modify the activity of the endogenous opioid system.

Hypothermia-induced Brugada-like electrocardiogram pattern

A patient in whom moderate hypothermia developed after prolonged cardiopulmonary resuscitation is described. Hypothermia was manifested by transient electrocardiogram changes, including long QT, precordial J waves, and downsloping ST-segment elevation ending in a negative T wave in leads V(1) and V(2) resembling the Brugada syndrome. The physiopathologic mechanisms of these electrocardiographic findings are discussed.

Brief review: anesthetic implications of long QT syndrome in pregnancy

PURPOSE

To review the effects of the long QT syndrome (LQTS) in the parturient and the current anesthetic management of patients with LQTS.

SOURCE

Relevant articles were obtained from a MEDLINE search spanning the years 1980-2006 and a PubMed search spanning the years 1949-2006. Bibliographies of retrieved articles were searched for additional articles.

PRINCIPAL FINDINGS

The prevalence of LQTS in the developed world is one per 1,100 to 3,000 of the population. Clinically, LQTS is characterized by syncope, cardiac arrest and occasionally, by a history of seizures. The QT interval can also be prolonged by drugs, electrolyte imbalances, toxins and certain medical conditions. Long QT syndrome patients are at risk of torsades de pointes and ventricular fibrillation. Medical management aims to reduce dysrhythmia frequency. The LQTS is subdivided into different groups (LQT1-6) depending on the cardiac ion channel abnormality. Torsades can be precipitated by adrenergic stimuli such as stress or pain (LQT1 and 2), sudden noises (LQT2) or whilst sleeping (LQT3). Patients with LQTS require careful anesthetic management as they are at high risk of torsades perioperatively despite minimal data on the effects of anesthetic agents on the QT interval. While information on effects of LQTS in pregnancy is limited, the incidence of dysrhythmia increases postpartum. Isolated case reports of patients with LQTS women highlight several peripartum dysrhythmias.

CONCLUSION

An understanding of LQTS and the associated risk factors contributing to dysrhythmias is important for anesthesthesiologists caring for parturients with LQTS.

Temperature modulation of ventricular arrhythmogenicity in a canine tissue model of Brugada syndrome

BACKGROUND

Fever promotes ventricular arrhythmias in Brugada syndrome (BrS). Hypothermia can induce BrS electrocardiogram (ECG) and arrhythmia. However, the mechanisms are unclear.

OBJECTIVE

We evaluated the hypothesis that pathological temperatures promoted arrhythmogenesis by modulating the spatial heterogeneity and functional dynamics of right ventricular electrophysiological activity.

METHODS

We mapped action potentials (APs) on the epicardial or cut-exposed transmural surfaces and recorded transmural ECGs in 27 arterially perfused canine right ventricular preparations before and after inducing BrS at 32 degrees C, 36.5 degrees C, and 40 degrees C.

RESULTS

We observed major intraepicardial dispersion of AP duration (APD) and reversal of transmural gradient of APD in association with manifestation of BrS at 36.5 degrees C. Reducing the temperature to 32 degrees C prolonged APDs and enhanced the phase 1 notch of epicardial APs, while 40 degrees C caused opposite changes. Prominent phase 2 domes of APs frequently led to spontaneous premature ventricular activations (PVAs), which conducted to surrounding regions having shorter APDs. Longer APDs at 32 degrees C and 36.5 degrees C frequently blocked reentry, although they promoted PVA, while shortened APDs at 40 degrees C facilitated reentrant ventricular tachycardia. During bradycardia (2,000 ms), the J-ST elevation in the ECG was enhanced at 32 degrees C and attenuated at 40 degrees C. Rapid pacing (500 ms) eliminated the dome of epicardial APs and enhanced J-ST elevation at each temperature. Blocking the transient outward current, I(to), with 4-aminopyridine reduced J-ST elevation and eliminated the PVA and reentry.

CONCLUSIONS

In this BrS model, prolongation and increased dispersion of APDs promoted spontaneous activation during hypothermia, while APD abbreviation facilitated reentry during hyperthermia. I(to) mediated the arrhythmogenicity.

Myocardial injury with biomarker elevation in diabetic ketoacidosis

We report of two patients with severe ketoacidosis, minute elevations of myocardial biomarkers (troponin T and CK-MB) and initial ECG changes compatible with myocardial infarction (MI). All successive investigations, including coronary arteriography, were normal, and the patients recovered fully without further evidence of ischemic heart disease. We suggest that acidosis and very high levels of free fatty acids could cause membrane instability and biomarker leakage. Regardless of the pathogenesis, these two case stories suggest that nonspecific myocardial injury may occur in severe diabetic ketoacidosis and that the presence of minute biomarker elevation and ECG changes does not necessarily signify MI.