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Noncardiac
thoracic (chest) surgery:
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The
frequency of delayed cardiac arrhythmias
following non-cardiac thoracic
surgery is greater than
is generally recognized.The average
incidence in our series, consisting
of 92 patients was 16.3 per cent.
It was greatest after pneumonectomy
(32.5 per cent) and [see table in
source pdf] after mediastinal exploration
and biopsy for neoplastic disease
(30 percent). The incidence was
higher in those over 50 years of
age.
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All
of the common atrial arrhythmias, including
atrial fibrillation, atrial flutter, paroxysmal
atrial tachycardia and multiple atrial premature
contractions were observed. The majority
of the arrhythmias occurred within two weeks
postoperatively and responded to conventional
therapy. The probable cause of delayed cardiac
arrhythmias is chronic vagal stimulation
and anoxia in an age group where coronary
sclerosis is prevalent. Infection or tumor
implants in the pericardium and mediastinal
tissues appear to be contributing factors
in many cases.
CARDIAC
RISK STRATIFICATION FOR NONCARDIAC SURGERY
Cardiac
risk stratification for noncardiac surgery
has evolved through medical technologic
and economic revolutions over the past 22
years. Prior to 1977, physicians had only
the anesthesia classes 1 to 5 to advise
their patients and families of the risks
of anesthesia and surgery. This clinical
index was subjective and did not predict
cardiac morbidity well.[1]
Goldman
et al[2] developed the first validated model
to predict cardiac complications in a general
surgical population. A cardiac risk index
for cardiac death and life-threatening complications
of myocardial infarction, pulmonary edema,
and ventricular tachycardia was defined
for patients in four risk classes. Patients
with angina were excluded from this early
study.
As
thallium scintigraphy became widespread
and IV dipyridamole became available, Boucher
et al[3] defined a 30% risk of perioperative
ischemic events in patients with redistribution
on thallium scans. This launched hundreds
of studies and articles to define preoperatively
the risk of general anesthesia and surgery
in patients with coronary heart disease
(CHD). The original cardiac risk index of
Goldman et al[2] was modified by Detsky
et al[4] in 1986 to include angina pectoris,
remote myocardial infarction, congestive
heart failure, aortic stenosis, and emergency
surgery. A simplified scoring system and
three classes of risk were validated on
patients undergoing vascular and nonvascular
surgery.
Combining
clinical criteria and thallium scan results
in patients undergoing major vascular surgery,
Eagle et al[5] found five clinical predictors
for cardiac complications. An age [is greater
than] 70 years, angina pectoris, diabetes
mellitus, Q waves on ECG, and premature
ventricular contractions on ECG were found
to be predictive of cardiac complications.
If the patient had one predictor, there
was a 3% risk of cardiac complications.
If there were two or three predictors, there
was a 3 to 15% risk, which increased to
a 30% risk if reperfusion was present on
thallium scans. If there were four or five
predictors, the risk was [is greater than]
15% and further preoperative cardiac studies
were indicated. From a practical and economic
standpoint, these criteria are still used
by many clinicians performing preoperative
evaluations.
Thallium
perfusion scans were utilized extensively
until 1991 when Mangano et al[6] found that
the scan results were not always predictive
of ischemic events. The development of stress
echocardiography and dobutamine stress echocardiography
provided a more convenient and less expensive
risk stratification procedure. Poldermans
et al[7] defined the benefits of dobutamine
stress echocardiography for assessment of
perioperative cardiac risk in patients undergoing
major vascular surgery. The use of atropine
to reach target heart rates in patients
undergoing dobutamine stress echocardiograms
increased the sensitivity and specificity
of this test.[8]
Because
of the enormous medical-legal and economic
implications of perioperative risk management
in patients with CHD, clinical practice
guidelines were published by the American
College of Cardiology, American Heart Association,
and the American College of Physicians.[9,10]
In
response to the membership of the American
College of Chest Physicians, this supplement
addresses the preoperative risk assessment,
the intraoperative management of cardiac
and pulmonary monitoring, fluids, and blood
transfusions, and the postoperative management
of pain, ventilation, nutrition, and renal
insufficiency. Special topics of elderly
patients and cancer patients are addressed.
Evidence-based tables are presented when
the literature can provide this analysis
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to "Paediatric Surgery"
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