Brugada syndrome: manifest, concealed, "asymptomatic," suspected and simulated

The hyperkalemic Brugada sign

BACKGROUND

A few case reports have indicated that hyperkalemia can induce a Brugada pattern in the electrocardiogram. The specific clinical and electrocardiographic features of the hyperkalemic Brugada sign, however, have not been previously described.

METHODS

A case series was collected from hospitalized hyperkalemic patients with a type I Brugada pattern in the electrocardiogram, and a literature review was performed. Electrocardiograms were examined for rhythm and morphology, and clinical characteristics were analyzed.

RESULTS

Nine new cases with the hyperkalemic Brugada sign were identified with an additional 15 cases found in the literature. Of the 9 cases, 8 were male patients, and all were critically ill; 5 of the 9 died within 48 hours. The mean (+/-SD) serum potassium level was 7.8 +/- 0.5 mEq/L. The mean QRS width was 144 +/- 31 milliseconds, and all had abnormal QRS axis. In 6 cases, there was a wide complex rhythm without visible P waves. The clinical and electrocardiographic characteristics of 15 cases found in the literature were remarkably similar to those in our series.

CONCLUSIONS

The hyperkalemic Brugada pattern differs in substantial ways from the electrocardiogram of patients with the genetic Brugada syndrome. Many patients have wide complex rhythms without visible P waves, marked QRS widening, and an abnormal QRS axis. Most patients are male, and many are critically ill. Prompt recognition of this clinical and electrocardiographic entity may expedite the initiation of appropriate treatment for hyperkalemia.

Age and gender difference in ST height at rest and after double autonomic blockade in normal adults

BACKGROUND

ST elevation is commonly seen in young, healthy men. The exact mechanisms that cause ST height to be greater in young men are not yet completely understood. The purpose of the present study was to determine whether autonomic tone is responsible for age and gender differences in ST height.

METHODS

Gender and age differences in ST height were studied at rest and after double autonomic blockade (DAB) with atropine and propranolol. Fifty healthy men and women were included (16 men, 14 women, age 23-32 years; 9 men, 11 women, age 65-79 years). Twelve-lead ECGs were registered at rest and after DAB. Leads II and V(1)-V(4) were chosen for analysis. ST height (in mm) was measured manually at the J-point, and 40 ms and 80 ms after the J-point. Values were corrected for QRS amplitude.

RESULTS

Gender and age differences in ST height were seen in both rest and DAB data. Men had greater ST height compared to women at J-point, 40 and 80 ms after the J-point (P < or = 0.0001), and younger subjects had greater ST height than older subjects at J-point (P = 0.0140), 40 and 80 ms after the J-point (P < or = 0.0001). DAB did not change ST height at J-point or at 40 ms, but increased ST height at 80 ms. Women had less of an increase in ST height following DAB than men did.

CONCLUSIONS

ST elevation in the absence of structural or electrical heart disease is mainly seen in young men. Age and gender difference persist after DAB and thus are not due to differences in autonomic tone.

Brugada-like electrocardiographic pattern: a challenge for the clinician

A right bundle branch block with ST-segment elevation in the V1-V3 leads in characteristic coved or saddleback configuration may be encountered as an incidental finding. However, not all patients with a Brugada-like electrocardiographic pattern are affected by the Brugada syndrome; in fact, this pattern may also be found in healthy individuals. Whether symptomatic patients affected by the syndrome are at a high risk of developing life-threatening ventricular arrhythmias and should immediately receive an automatic, implantable defibrillator is open to debate, as is the clinical management of asymptomatic patients, because data from the scientific literature are controversial. Implications of the diagnosis and the treatment of this category of patients are discussed.

Brugada electrocardiographic pattern in a postoperative patient

OBJECTIVE

To report the development of the Brugada electrocardiographic (ECG) pattern in the immediate postoperative setting.

DESIGN

Case report.

SETTING

Postanesthesia care unit at Memorial Sloan-Kettering Cancer Center.

PATIENT

A 51-yr-old white male who developed new ST-segment elevation in leads V(1)-V(3) typical of the ECG changes of the Brugada syndrome immediately after undergoing head and neck surgery for cancer. The patient was asymptomatic, and the cardiac enzymes and echocardiogram were normal; therefore, electrophysiologic study was not performed.

CONCLUSIONS

We postulated that the Brugada ECG abnormalities were induced primarily by an increase in parasympathetic tone resulting from vagal nerve manipulation during deep neck dissection and partially by the fever he developed during the postoperative period. In addition to the more common causes of ST-segment elevation, the Brugada ECG pattern or syndrome should be considered in patients undergoing deep neck dissection who develop characteristic ECG changes in association with normal cardiac enzymes and echocardiogram.

Heritability and a genome-wide linkage scan for arterial stiffness, wave reflection, and mean arterial pressure: the Framingham Heart Study

BACKGROUND

Arterial stiffness and mean arterial pressure variably contribute to systolic hypertension and increased cardiovascular risk. However, few prior community-based studies have evaluated the genetics of arterial stiffness and separate mean and pulsatile components of blood pressure.

METHODS AND RESULTS

Using arterial tonometry, we evaluated heritability and linkage of forward and reflected wave amplitude, mean arterial pressure, and carotid-femoral pulse wave velocity (CFPWV) in 1480 participants representing 817 pedigrees in the Framingham Study offspring cohort. In 204 families with tonometry data, a genome-wide scan was performed with microsatellite markers that covered the genome at 10-cM intervals. Heritability estimates were moderate for reflected wave amplitude (h2=0.48), forward wave amplitude (h2=0.21), CFPWV (h2=0.40), and mean arterial pressure (h2=0.33). Variance components linkage analysis identified 2 regions of linkage for reflected wave amplitude: chromosome 4 at 181 cM (logarithm of odds [LOD]=4.93, permuted P=0.002) and chromosome 8 at 33 cM (LOD=3.27, permuted P=0.058). There was 1 region of linkage for forward wave amplitude on chromosome 7 at 174 cM (LOD=2.88, permuted P=0.017). There were several regions of suggestive linkage for CFPWV: chromosome 2 at 94 cM (LOD=2.46), chromosome 7 at 29 cM (LOD=2.50), chromosome 13 at 108 cm (LOD=2.10), and chromosome 15 at 108 cM (LOD=2.48). There was 1 region of suggestive linkage for mean arterial pressure on chromosome 1 at 192 cM (LOD=2.18).

CONCLUSIONS

Arterial stiffness measures and mean and pulsatile components of blood pressure are heritable and appear to have genetic determinants that may be linked to separate genetic loci in humans.

Prevalence and time of appearance of Brugada electrocardiographic pattern in young male adolescents from a three-year follow-up study

The prevalence of Brugada's electrocardiographic (ECG) pattern in 7,022 male adolescents in the seventh grade was determined, and the same subjects were reexamined 3 years later, while in tenth grade. Two subjects (0.03%) and 7 subjects (0.10%) showed Brugada's ECG pattern by the conventional criterion (J point or ST-segment >/=0.1 mV in leads V(1) to V(3)), and no subjects (0%) and 2 subjects (0.03%) fulfilled the recent criterion (J point or ST-segment >/=0.2 mV) in the seventh and tenth grades, respectively, indicating that Brugada's ECG pattern begins to appear during junior high school and increases until late adulthood.

Worrisome Thoughts About the Diagnosis and Treatment of Patients With Brugada Waves and the Brugada Syndrome

The Brugadas have made a significant contribution to medicine. Their discovery of a new clinical syndrome and ECG abnormalities has created a great deal of interest and has opened Pandora’s box. Here, we discuss some worrisome thoughts about the condition. We stress the need for improved diagnostic criteria and treatment because it is not always possible to perform coronary arteriography, electrophysiological studies, right ventricular myocardial biopsy, and MRI in all patients in whom ST-segment abnormalities are seen in the ECG, especially in patients who are asymptomatic. Accordingly, further research is needed to guide the clinician in the diagnostic and therapeutic problems of patients who have unusual ST segments in leads V 1 and V 3 . We present a patient who illustrates the problem.

Brugada syndrome and "Brugada sign": clinical spectrum with a guide for the clinician

BACKGROUND

Patients with the manifest Brugada syndrome have an inordinate risk of sudden death and are candidates for implantation of a defibrillator. The Brugada type electrocardiogram (ECG) abnormality (the "Brugada sign"), however, is known to be associated with a wide range of conditions, many of which may not pose such a threat. Clinicians need guidance in choosing a rational approach for the evaluation and treatment of patients with a finding of the Brugada sign.

METHODS

A systematic literature search was performed to identify publications on the Brugada syndrome and the Brugada-type ECG abnormality, with special emphasis on analyzing outcomes data. In addition, the ECG database of our institution was reviewed for tracings consistent with the Brugada sign, and, when possible, clinical correlations were made.

RESULTS

Patients with the Brugada sign and a family history of sudden death or a personal history of syncope are at a high risk of sudden death and therefore should be strongly considered for implantation of a defibrillator. In patients who are hospitalized and critically ill, the Brugada sign is frequently the result of severe hyperkalemia, drug toxicity, or right ventricular injury. In most individuals with no symptoms and without a family history of sudden death, the Brugada sign is likely a normal variant.

CONCLUSIONS

Most patients with the Brugada sign can be risk-stratified with simple clinical tools. Specific testing for the Brugada syndrome should be reserved for questionable cases and for the research setting. A provisional diagnostic-therapeutic algorithm is offered as a means of assisting the clinician in the evaluation and treatment of patients with the Brugada sign.

Electrocardiographic effects of intravenous cocaine: an experimental study in a canine model

Cocaine abuse causes cardiac dysfunction. Acute intravenous administration of cocaine may lead to development of severe arrhythmias, conduction abnormalities, ST-T changes, and sudden death. Understanding arrhythmogenesis due to cocaine may provide a therapeutic approach to reduce morbidity and mortality. We studied the arrhythmogenic activity and other electrocardiographic abnormalities resulting from an intravenous bolus of cocaine. Baseline and postanesthetic electrocardiographic findings were compared with those after administration of intravenous bolus of various doses of cocaine hydrochloride in 20 dogs. The study was done in three phases (phase I: low dose of cocaine [1 mg/kg, 15 experiments]; phase II: medium dose [2 mg/kg, 30 experiments]; and phase III: high dose [5-7 mg/kg, 10 experiments]). Plasma levels of cocaine were estimated. The low dose induced sinus bradycardia, sinus arrhythmia, atrial ectopic, wandering pacemaker, unifocal ventricular premature contractions, and ventricular couplets. The medium dose generated moderately severe arrhythmias that were of supraventricular origin. Atrial flutter and atrial fibrillation were observed in two experiments each. Ventricular arrhythmias were manifested as unifocal, multifocal, interpolated ventricular premature contractions as well as bigeminy, trigeminy, couplets, and salvos. The high dose of 5-7 mg/kg increased electrocardiographic intervals and caused ST-segment elevation as well as serious life-threatening arrhythmias. Three of the dogs developed sustained ventricular tachycardia followed by ventricular flutter-fibrillation and death.

Tricyclic antidepressants and the Brugada syndrome: an example of Brugada waves appearing after the administration of desipramine

Since its initial description in the early 1990s, the Brugada syndrome has become increasingly familiar to active researchers and practicing clinicians. The Brugada wave, a characteristic electrocardiographic abnormality of downsloping ST-segment elevation in leads V1-V3 and right bundle-branch block morphology, has now been associated with an increased risk of sudden death. Currently, very little is known about the relationship between the Brugada syndrome and tricyclic antidepressants. Accordingly, we report the case of a patient who developed prominent Brugada waves with the administration of increasing doses of desipramine. We believe the mechanism of Brugada wave augmentation or production secondary to tricyclic antidepressants is consistent with the current model of early repolarization. We also speculate that the increased risk of sudden death that may occur with tricyclic antidepressants could be related to the development of the Brugada syndrome. We advocate the judicious use of tricyclic antidepressants in cardiac and elderly patients, with careful monitoring of the electrocardiogram for the development Brugada waves.