| |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
|
|
|||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Brugada syndrome is characterized by a distinctive electrocardiographic pattern (right bundle branch block and ST segment elevation in precordial leads) and a high risk of cardiac arrest for malignant dysrhythmia. The genetic basis is a molecular defect of the cardiac sodium channel and the pattern of inheritance is autosomal dominant. Many factors during general anesthesia (medications, bradycardia, temperature changes) could precipitate malignant dysrhythmia in these patients. Because criteria to identify the surgical patient at high risk for developing malignant dysrhythmia are lacking, we can only speculate about the available studies on nonsurgical patients. We describe four patients during general anesthesia and propose intraoperative and postoperative monitoring (the first 36 h).
In 1992, Brugada and Brugada (1) described eight patients who were resuscitated from cardiac arrest without demonstrable structural heart disease but who presented right bundle branch block and ST segment elevation in leads V1V2V3. These cases established this electrocardiographic (ECG) pattern as a distinctive new syndrome associated with augmented risk of sudden death. Since then, the genetic basis of the syndrome has been reported (2): a molecular defect of gene SCN5A encoding the cardiac sodium channel mapped to 3p21-p23. Familial occurrence has been described with an autosomal dominant pattern of inheritance. Brugada et al. (3) proposed that asymptomatic patients are at high risk of cardiac arrest (approximately 60% of patients within 1 year from the diagnosis); thus justifying aggressive therapy such as the implantation of a cardioverter-defibrillator. A prospective study (4) reported that in asymptomatic patients the risk of cardiac arrest is infrequent enough to justify postponing implantation of a cardioverter-defibrillator. Many factors (medications, bradycardia, temperature changes) during general anesthesia could precipitate malignant dysrhythmia in these patients.
Our experience concerns 4 patients with Brugada Syndrome who underwent surgical intervention from September, 2000 to December, 2002. The diagnosis of the syndrome was easily obtained by ECG; all patients presented incomplete right bundle branch block and ST segment elevation 0.1 mV in precordial leads. Structural heart disease or coronary artery disease were excluded by noninvasive tests and the absence of creatine phosphokinase elevations. Only one patient had a history of aborted sudden death and syncopes caused by torsades de pointes. The others were asymptomatic. During general anesthesia, continuos ECG (DI, DII, DIII, aVL, aVF, aVR, V5) with online analysis of dysrhythmia and ST segment, invasive arterial blood pressure by radial artery cannulation, arterial oxygen saturation, end-tidal CO2, esophageal temperature, and urine output were monitored. Only one patient had an implanted cardioverter-defibrillator at the time of operation. It was turned off for surgery. Patients received preanesthesia diazepam orally. General anesthesia, after induction with propofol, fentanyl, and cisatracurium, was maintained with sevoflurane, cisatracurium, and fentanyl. Ventilation was controlled and monitored by analysis of arterial blood gases. At awakening we avoided any stimulation and began postoperative analgesia with continue infusion of ketorolac and opioids through an elastomeric pump. An external defibrillator, connected to defibrillation pads placed on the patient, was available in the operating room during surgery.
All patients (Table 1) were males 25 to 43 yr of age; two underwent emergency operation for acute appendicitis and two had elective urologic operations (varicocelectomy and transurethral prostatectomy). One patient, after appendectomy, developed hemoperitoneum. Every patient presented ST segment elevation in precordial leads between 0.1 and 0.2 mV (Fig. 1) and incomplete right bundle branch block. During anesthesia, one patient presented rare ectopic beats during ECG monitoring. Neither dysrhythmias nor ST segment elevation were observed. The esophageal temperature was kept
Every patient was admitted to the cardiac intensive care unit for a postoperative period of at least 36 h; no patient presented worsening in ST segment elevation. The patient who had hemoperitoneum had sinus tachycardia without changes in the ST segment.
The prevalence of Brugada syndrome has not been accurately estimated but, according to previous studies, the disease is not uncommon. The incidence may be even more frequent in the younger population and it is the most common cause of sudden death in individuals younger than 50 years without underlying cardiac disease in the Japanese population (5) and in South Asia (6). Roberts and Brugada (7) report an estimated incidence of this form of sudden death between 26 and 38 per 100,000 people per year. Anesthesiologists should be aware of Brugada syndrome because it is not a rare disease; from 20% to 60% of idiopathic ventricular fibrillation could be associated with this syndrome.
Risk stratification in these patients is important for defining treatment: e.g., the choice of cardioverter-defibrillator implantation (4). Current studies only propose risk stratification for nonsurgical patients; the few reports available did not demonstrate any heart rate instability, electrical storm or other adverse events during surgery, therefore more data are necessary for a better risk evaluation in surgical patients. We can only extrapolate this information from the studies conducted in nonsurgical patients. Priori et al. (4) showed, in a prospective evaluation, that asymptomatic subjects are at less risk for sudden death and that management strategies should be based on risk stratification algorithms. Brugada et al. (8) proposed a risk stratification scheme based on screening with programmed electrical stimulation of asymptomatic patients, but this test is not reproducible and it is useless for risk stratification (4,9,11). Other authors proposed different criteria for risk stratification but they all need to be confirmed: Priori et al. (9) proposed S wave width All our patients presented an ECG pattern of Brugada syndrome at rest, incomplete right bundle branch block, and different width of ST elevation from V1 to V3. Applying the criteria reported above, three of our patients were in a high risk or intermediate risk subgroup for malignant dysrhythmias. During general anesthesia, many factors could precipitate ventricular fibrillation in these patients. This is only the fifth report about general anesthesia administration in patients with Brugada Syndrome. In a study from Japan (12) concerning a patient without obvious heart disease, and in a study by Brugada et al. (3), it has been suggested that bradycardia could precipitate arrhythmia and that the degree of ST elevation increases with the heart rate. Polymorphic ventricular fibrillation is also inducible with one or two ventricular premature beats during ventricular pacing. For this reason we monitored the ECG trace and used an automated ECG ST segment trending monitor (Datex, Helsinki; Finland) (13) to detect any change. During anesthetic induction with propofol all of our patients had a decrease in heart rate without changes in the ST segment. During anesthesia their heart rates were stable and never <60 bpm.
Many drugs can have a proarrhythmic effect. In patients with Brugada syndrome, Class I antiarrhythmic drugs (14) sodium channel blockers (specifically procainamide and ajmaline) can induce ST segment elevation because they interact directly with the receptors affected by the syndrome. The muscarinic and The ion channel abnormality of Brugada syndrome should be temperature sensitive (18); we therefore monitored esophageal temperature in every patient. Cardiac arrhythmias, even in the general population, are most likely to occur in the postoperative period (19); therefore it was necessary, during recovery in the intensive care unit, to detect and treat them. Hence, we decided to monitor our patients for 36 postoperative hours. Brugada syndrome is an increasingly recognized disorder. The ECG pattern should alert the clinician to suspect possible Brugada syndrome. If this finding is confirmed further investigation is justified. However, there is a degree of genetic heterogeneity, and some patients affected by the syndrome do not show the typical ECG pattern. Follow-up data indicate that the risk of ventricular tachyarrhythmia is minimal in the absence of a resting ECG abnormality and the absence of adverse events reported during anesthesia should be reassuring. For these patients many situations that could precipitate ventricular fibrillation happen during anesthesia. Even if the few reports (12,20,21) did not detect any arrhythmic problem, it is difficult to draw a firm conclusion, especially because of the heterogeneous nature of the mutation leading to Brugada syndrome. Risk stratification criteria currently do not allow identification of patients who run the risk of malignant arrhythmias, and surgical patients probably need different criteria for this stratification. It is our opinion that with an adequate anesthetic plan the risk during major or minor procedures should be the same; during major procedures the risk may be increased for the longer procedure time. Even if there were no reported problems during surgery, general, regional, or local anesthesia should be carefully managed and should include, at least, monitoring ST segment on ECG, measuring invasive arterial blood pressure and body temperature, keeping an external defibrillator ready in the operating room and, if possible, avoiding drugs that could trigger arrhythmias. We used the necessary intraarterial blood pressure monitoring to readily detect the hemodynamic effects of any dysrhythmia or any drug or other trigger mechanism. Anesthesiologists should consider the risk/benefit ratio of arterial cannulation, especially for short surgery procedures or for regional and local anesthesia.
Accepted for publication October 12, 2004.
This article has been cited by other articles:
|
|||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
|