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TheAnswerPage/Anesthesiology
Monday
February 08, 2010
This week:
Bradyarrhythmias
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What is the incidence of perioperative arrhythmias?
The incidence of perioperative arrhythmias depends on the
definition, the method and frequency of surveillance, patient
characteristics and the type of surgery (1). While patients
undergoing cardiothoracic surgery have the highest reported incidence
(greater than 90%), even ASA 1 and 2 patients undergoing general
anesthesia for a variety of procedures have a greater than 70%
incidence of tachycardia, bradycardia, or other dysrhythmias (2). Of
note, Forrest et al.(2) noted in healthy patients undergoing general
anesthesia that severe ventricular arrhythmias and tachycardias were
more common with halothane and isoflurane, respectively.
What are some predisposing factors for postoperative
arrhythmias?
A number of factors have been associated with perioperative
arrhythmias, including (3):
- hypoxemia
- hypercarbia
- myocardial ischemia
- endogenous or exogenous catecholamines
- electrolyte or acid base imbalances
- drug effects
- mechanical factors, such as instrumentation
Certainly arrhythmias may be multifactorial, and the search for a
single etiology may be an oversimplification. Regardless,
identification and correction of potential etiologies is necessary
for the management of these arrhythmias. The duration, severity, and
resulting (or existing) cardiac function should all be considered in
this determination. Of note, while the above listed factors may
initiate a dysrhythmia, they are more likely to occur in patients
with underlying structural heart disease (1). Moreover, the factors
listed above may ultimately utilize a common final pathway to result
in dysrhythmias; Sipido et al. (4) utilizing a canine myocyte model,
suggested that the Ca(2+) influx via the Na/Ca exchanger (in contrast
to L-type calcium channels) appeared to prolong nonhomogeneous action
potentials, leading to arrhythmogenic currents.
What has been responsible for the advances in the diagnosis and
management of dysrhythmias in the past 30 years?
Improvement in evaluating, understanding and treating dysrhythmias
have been the result of (1):
- enhancement of a mechanistic understanding of
dysrhythmias,
- availability of new drugs for treatment (including adenosine,
amiodarone, bretylium, diltiazem, esmolol, ibutilide, and
verapamil),
- ability to intentionally trigger (and control) potentially
lethal dysrhythmias,
- technologic advances in transcutaneous and transesophageal
pacing
- advances in surgical or catheter ablation of dysrhythmic foci
or reentrant pathways.
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References:
- Atlee JL. Perioperative cardiac dysrhythmias: diagnosis and
management. Anesthesiology 1997;86(6):1397-424.
- Forrest JB, Cahalan MK, Rehder K, et al. Multicenter study of
general anesthesia. II. Results. Anesthesiology
1990;72(2):262-8.
- Hollenberg SM, Dellinger RP. Noncardiac surgery: Postoperative
arrhythmias. Crit Care Med 2000; 28:(suppl) N145-50.
- Sipido KR, Volders PG, de Groot SH, et al. Enhanced Ca(2+)
Release and Na/Ca Exchange Activity in Hypertrophied Canine
Ventricular Myocytes : Potential Link Between Contractile
Adaptation and Arrhythmogenesis. Circulation
2000;102(17):2137-2144
Site Editor: Stephen B. Corn, M.D. and B. Scott Segal, M.D.
Department of Anesthesia, Harvard Medical School
Founders
and Editors-in-Chief: Stephen B. Corn, M.D. and B. Scott Segal,
M.D.
Department of Anesthesiology, Perioperative and Pain Medicine, Harvard Medical School
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