Case debriefing
The patient, a 70-year-old male, was admitted to the hospital with gastric cancer and was scheduled to undergo elective radical gastrectomy. Previous history of coronary heart disease and diabetes mellitus, interventional treatment for acute myocardial infarction 1 year ago, and a stent was placed in the left anterior descending artery. The drugs currently taken are: aspirin, ticagrelor, irbesartan, acarbose, etc.
section
Coronary CTA
With the increase in life expectancy and the aging of the population, more and more patients undergoing surgical treatment have comorbid cardiovascular disease or have cardiovascular disease risk factors. These patients need to undergo a risk assessment of cardiovascular events in the perioperative period, and those with definite cardiovascular disease need to be assessed for the timing of surgery and adjust current medications to minimize the risk of adverse cardiovascular events (MACE) in the perioperative period.
Perioperative myocardial infarction (PMI) or myocardial injury is one of the most important risk factors for short- and long-term morbidity and mortality during noncardiac surgery. Therefore, prevention of PMI can improve postoperative outcomes.
PART 01
Preoperative evaluation
Preoperative risk assessment of adverse cardiovascular events
The Modified Cardiac Risk Index (RCRI) uses six independent cardiac risk-related factors:
high-risk surgery;
History of ischemic heart disease (IHD);
充血性心力衰竭(CHF)病史；
history of cerebrovascular disease;
Diabetes mellitus treated with insulin before surgery;
术前血清肌酐浓度高于2mg/dl。
Easy to remember: (high-risk, ischemia, congestion, cerebral blood, blood glucose, serum creatinine)
It was concluded that the risk of serious cardiac complications (MI, pulmonary edema, ventricular fibrillation, and primary cardiac arrest) was 0.5%, 1.3%, 4%, and 9%, respectively, with 0, 1, 2, and 3 risk factors.
Preoperative cardiac marker test
B-type natriuretic peptide (BNP) and N-terminal B-type natriuretic peptide (NT-proBNP) are commonly used serum markers of heart failure. When the preoperative BNP level was ≥92 ng/L or the NT-ProBNP level was ≥ 300 ng/L, the incidence of death or myocardial infarction within 30 days after surgery was increased. Troponin T and I are commonly used to diagnose myocardial infarction or myocardial injury, and elevated baseline troponin levels are associated with increased perioperative myocardial infarction and long-term mortality. Myocardial infarction is a complication with a high incidence of NCS (non-cardiac surgery), so for patients at high risk of cardiovascular events, troponin testing should be completed preoperatively and monitored for elevation after surgery to detect myocardial infarction in time.
Preoperative cardiovascular examination
Discontinuation of the drug before surgery
Patients with comorbid heart disease are usually treated with multiple medications taken by mouth. Antianginal drugs, particularly β blockers and statins, should be continued into surgery. Abrupt discontinuation of antianginal drugs can lead to rebound tachycardia and hypertension, leading to acute myocardial ischemia and myocardial infarction (MI). Antihypertensive therapy should be continued through the day of surgery, especially β-blockers, calcium-channel blockers, and nitrates. Stopping angiotensin-converting enzyme (ACE) inhibitors and angiotensin II receptor blockers (ARBs) 24 hours before surgery remains controversial. In patients who are chronically treated with ACE inhibitors, persistent hypotension may occur during general anesthesia. Caution should be exercised in patients who may have significant intraoperative fluid metastases or massive blood loss24 and discontinue ACE inhibitors and ARBs preoperatively. Hypotension caused by ACE inhibitors is usually sensitive to fluids and/or sympathomimetic drugs such as phenylephrine and ephedrine. If hypotension remains recalcitrant despite these treatments, vasopressin or its long-acting derivative (terlipressin) may be effective. Oral hypoglycemic drugs metformin, pioglitazone, glibenclamide, rosiglitazone, etc. should be stopped on the morning of the day of surgery.
PART 02
Choice of anesthetic modality
Studies have shown that regional block and general anesthesia have no significant intrinsic advantage over perioperative cardiac morbidity and mortality in peripheral vascular surgery. With the widespread development of ultrasound-guided nerve blocks, general anesthesia combined with ultrasound-guided TAP block should be a more appropriate choice.
Precautions for induction of general anesthesia
Prevention of hypotension, hypertension, and tachycardia, all of which can lead to myocardial ischemia.
Commonly used drugs: (1) Intravenous induction drugs such as midazolam, etomidate, and propofol have their own advantages and disadvantages, and the advantages and disadvantages are also relative, the focus is on the use of drugs, and the anesthesia implementer should be flexibly mastered according to the different conditions of patients, and the strengths and weaknesses should be avoided. Etomidate has good hemodynamic stability, especially for patients with coronary artery disease (CAD), the induction dose is 0.2~0.3mg/kg, and the side effects are inhibition of adrenal cortex function and muscle spasm. (2) In order to alleviate the stress response during endotracheal intubation, an appropriate amount of opioids should be added. Remifentanil has a short onset time and is suitable for anesthesia induction, with a common dose of 0.5~1μg/kg. Fentanyl 2.5~5μg/kg or sufentanil 0.25~0.5μg/kg can also be used, and small doses of the β receptor blocker esmolol 0.25~0.5mg/kg and lidocaine 1mg/kg can also be added as needed. (3) Muscle relaxants can be chlorosuccinylcholine or fast-acting non-depolarizing muscle relaxants such as rocuronium.
PART 03
What should I do if the ECG shows myocardial ischemia during surgery?
Characteristics of perioperative myocardial ischemia: the incidence of perioperative myocardial ischemia in patients with coronary heart disease or risk factors is 20%~63%. Postoperative myocardial ischemia is most common throughout the perioperative period, and most high-risk patients typically occur on the day of surgery or on the first postoperative day, while myocardial ischemic events tend to begin at the end of surgery and when awake from anesthesia. More than 90% of postoperative myocardial ischemic events are asymptomatic. Electrocardiographic analysis of perioperative myocardial ischemia revealed ST-segment depression in almost all cases, and ST-segment elevation was rare. Most postoperative myocardial infarctions occur in the early postoperative period, without obvious clinical symptoms, and 60%~100% are non-Q wave myocardial infarctions, and there is ST-segment depression before occurring.
Cardiovascular surgery center electrographic monitoring recommends a combination of lead II and V5 to increase the sensitivity of diagnosing myocardial ischemia. Diagnostic criteria for perioperative myocardial ischemia are horizontal and downward inclined ST-segment depression of 0.1 mV, ST-segment elevation of 0.1 mV in non-Q leads, and slow