Cardiac Path Online
Perioperative Cardiac Pathology
Postmortem examination is advisable in any patient who dies unexpectedly after a surgical procedure.
Good working relationships with the Coroner are essential to ensure that the correct type of case is accepted for autopsy.
An essential preliminary to the postmortem is a detailed examination of the clinical records, paying particular attention to the operative reports, details of intravenous fluid administration and urine output .
The classical pattern of postmortem examination must be abandoned in these cases and under no circumstances should a technician be allowed to eviscerate the body before the arrival of the pathologist.
When obvious pathology such as pneumonia, other causes of sepsis, hemorrhage and pulmonary embolism have been excluded all that remains to explain the death of the patient is cardiogenic pulmonary edema. The cause of death is given as cardiac failure.
Many separate studies have shown that postoperative myocardial infarction is extremely rare in patients with no previous evidence of ischaemia, but relatively common in patients with evidence of previous ischaemic heart disease.
Patients undergoing peripheral vascular surgery are particular candidates for perioperative ischaemia and preoperative electrocardiographic monitoring is a useful method for assessing cardiac risk.
Many postoperative myocardial infarcts occur some time after, rather than during,the operative procedure and, until recently, this was unexplained.
Most ischaemic episodes occurred after, rather than before or during, operation.
The usual ECG abnormality was ST segment depression, suggesting that subendocardial ischaemia, rather than acute coronary artery occlusion, was the responsible mechanism.
Transient anoxia may occur during the induction of anaesthesia, especially if there are associated variation in heart rate.
The clinical diagnosis of post operative infarction is very difficult. The pain is often masked by analgesic drugs or is confused by the discomfort of the surgical procedure itself.
There is a good correlation between the development of postoperative pulmonary oedema and preoperative evidence of heart failure.
Nevertheless, more than 50% of patients over 65 years who develop post operative heart failure have no previous evidence of myocardial disease.
Postoperative pneumonias occur in about 20% of all patients who have had thoracic or abdominal operations but are extremely rare in other procedures in previously fit individuals.
The incidence of postoperative pneumonia is at increased :
(i) in weight greater than 120 kg
(ii) age greater than 70 years males more than females
(iii) smokers more than non-smokers
(iv) in operation lasting longer than 2 hours.
A detailed dissection of the heart is therefore essential.
It is important to determine whether there was any preoperative evidence of cardiac failure or myocardial ischaemia.
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