Postmortem examination is advisable in any patient who dies unexpectedly after a surgical procedure.

Visit: Postoperative cardiac pathology (Death after Cardiac Surgery)

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.

Before accepting this it is essential to determine whether there was any preoperative evidence of cardiac failure or myocardial ischaemia.  

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 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 pneumoniaa 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. 

The pathological investigation of deaths following surgery, anaesthesia, and medical procedures is discussed. The definition of "postoperative death" is examined and the classification of deaths following procedures detailed. The review of individual cases is described and the overall approach to necropsy and interpretation considered. There are specific sections dealing with the cardiovascular system (including air embolism, perioperative myocardial infarction, cardiac pacemakers, central venous catheters, cardiac surgery, heart valve replacement, angioplasty, and vascular surgery); respiratory system (postoperative pneumonia, pulmonary embolism, pneumothorax); central nervous system (dissection of cervical spinal cord), hepatobiliary and gastrointestinal system; musculoskeletal system; and head and neck region. Deaths associated with anaesthesia are classified and the specific problems of epidural anaesthesia and malignant hyperthermia discussed. The article concludes with a section on the recording of necropsy findings and their communication to clinicians and medicolegal authorities.

Perioperative myocardial infarct during the surgical treatment of IHD.
Anesteziol Reanimatol. 1999 Sep-Oct;(5):34-7.

Perioperative myocardial infarction is one of the most frequent causes of death in patients subjected to surgery for coronary disease. Study of the pathogenesis of this complication may become an approach to decreasing the postoperative mortality. Forty-seven case histories and autopsy protocols of patients who died after surgery on the coronary arteries and 241 intraoperative biopsy specimens of autovenous shunts are analyzed. The mechanisms underlying the cardiomyocyte necrosis in surgical treatment of coronary disease are based on various pathological processes, the leading of which is thrombosis of the shunts and coronary arteries. The principal factors were intraoperative ischemia of autovein endothelium and shunting of coronary artery with a narrow distal bed.

Post-mortem examination after cardiac surgery.Histopathology. 1998 Nov;33(5):399-405.

Following a recent enquiry into surgery at a paediatric cardiac centre in England, there will be substantial changes in the way that the success and failure of surgical procedures will be monitored and investigated. Post-mortem examinations on patients dying after cardiac surgery are likely to be performed and reported in more detail. This review describes the protocol that we have developed and summarizes recent clinical and pathological studies that have increased our understanding of postoperative pathophysiology. Close attention should be paid to the history, particularly the operation note. Cardiac failure is the commonest cause of death. We believe this is a clinicopathological diagnosis and provide definitions of preoperative and perioperative cardiac failure. Haemorrhage, stroke, pulmonary emboli and infection are other important causes of death. Methods of dissection are suggested for bypass grafts and valve replacements. Two recent studies show that the post-mortem examination provides answers to most clinical questions and reveals an unexpected cause of death in 10-15% of patients. There are limitations however: an incomplete or indeterminate cause of death is found in 14-25% of patients, most commonly sudden clinically unexplained death or clinically unexplained cardiac failure soon after surgery.

Analysis of risk factors for myocardial infarction and cardiac mortality after major vascular surgery. Anesthesiology. 2000 Jul;93(1):129-40

Patients undergoing vascular surgical procedures are at high risk for perioperative myocardial infarction (PMI). This study was undertaken to identify predictors of PMI and in-hospital death in major vascular surgical patients. METHODS: From the Vascular Surgery Registry (6,948 operations from January 1989 through June 1997) the authors identified 107 patients in whom PMI developed during the same hospital stay. Case-control patients (patients without PMI) were matched at a 1x:x1 ratio with index cases according to the type of surgery, gender, patient age, and year of surgery. The authors analyzed data regarding preoperative cardiac disease and surgical and anesthetic factors to study association with PMI and cardiac death. RESULTS: By using univariable analysis the authors identified the following predictors of PMI: valvular disease (P = 0.007), previous congestive heart failure (P = 0.04), emergency surgery (P = 0.02), general anesthesia (P = 0.03), preoperative history of coronary artery disease (P = 0.001), preoperative treatment with beta-blockers (P = 0.003), lower preoperative (P = 0.03) and postoperative (P = 0.002) hemoglobin concentrations, increased bleeding rate (as assessed from increased cell salvage; P = 0.025), and lower ejection fraction (P = 0.02). Of the 107 patients with PMI, 20.6% died of cardiac cause during the same hospital stay. The following factors increased the odds ratios for cardiac death: age (P = 0.001), recent congestive heart failure (P = 0.01), type of surgery (P = 0.04), emergency surgery (P = 0.02), lower intraoperative diastolic blood pressure (P = 0.001), new intraoperative ST-T changes (P = 0.01), and increased intraoperative use of blood (P = 0.005). Patients who underwent coronary artery bypass grafting, even more than 12 months before index surgery, had a 79% reduction in risk of death if they had PMI (P = 0.01). Multivariable analysis revealed preoperative definitive diagnosis of coronary artery disease (P = 0.001) and significant valvular disease (P = 0.03) were associated with increased risk of PMI. Congestive heart failure less than 1 yr before index vascular surgery (P = 0. 0002) and increased intraoperative use of blood (P = 0.007) were associated with cardiac death. The history of coronary artery bypass grafting reduced the risk of cardiac death (P = 0.04) in patients with PMI. CONCLUSIONS: The in-hospital cardiac mortality rate is high for patients who undergo vascular surgery and experience clinically significant PMI. Stress of surgery (increased intraoperative bleeding and aortic, peripheral vascular, and emergency surgery), poor preoperative cardiac functional status (congestive heart failure, lower ejection fraction, diagnosis of coronary artery disease), and preoperative history of coronary artery bypass grafting are the factors that determine perioperative cardiac morbidity and mortality rates.

Acute ischaemic lesions in death due to ischaemic heart disease. An autopsy study of 333 cases of out-of-hospital death.Eur Heart J. 1995 Sep;16(9):1181-5.

The frequency of acute coronary artery thrombus and myocardial infarction in subjects dying suddenly or unexpectedly from ischaemic heart disease (IHD) is still unclear, with previous autopsy studies reporting an incidence between 4% and 100%. In this study of 333 randomly selected out-of-hospital deaths, detailed autopsy showed IHD as the sole cause of death in 206 (62%). One hundred and seventeen acute coronary thrombi were present in 96 cases whilst four had an established acute infarct without an identifiable coronary thrombus. Thus 100 (48.5%) IHD deaths had evidence of an acute ischaemic lesion. Acute lesions were equally prevalent among males and females, but the incidence declined with increasing age and they were less frequent among those with a prior clinical history of heart disease. One hundred and forty-seven IHD deaths were witnessed. The proportion of cases with an acute ischaemic lesion increased with the duration of pre-morbid symptoms. Of those with an acute lesion, only 17% died without symptoms compared to 63% of those without an acute lesion. All cases with symptoms lasting more than 3.5 h had an acute lesion. Overall, almost half out-of-hospital IHD deaths in this study were related to an acute ischaemic lesion. Differences in the detail of the pathological examination and examination of differing sub-groups of the out-of-hospital death population probably account for the differing results of previous studies.

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