With the aging of society, the incidence of coronary heart disease has increased significantly. According to statistics, about 2/3 of elderly people over 65 years of age can have coronary heart disease, and according to Mangano, the incidence of coronary heart disease is 80.2% in 1000 patients. Therefore, non-cardiac surgery in coronary patients is the majority of the elderly cardiac patients. Non-cardiac surgery for other heart diseases is relatively rare.
I. Anesthesia and preoperative disease estimation
(A) Estimation of cardiac function
According to the four-level classification of New York Heart Association (NYHA), cardiac function can be divided into four levels: level I is asymptomatic, daily activities do not cause fatigue, palpitations and dyspnea; level II is mildly limited in daily activities, and fatigue, palpitations, dyspnea or angina can occur, but feel comfortable after rest; level III is significantly limited in physical activity, mild activity that is symptomatic, but still feel comfortable after rest Class Ⅳ is the symptoms of cardiac insufficiency or angina syndrome even at rest, and any physical activity will increase the discomfort. If the cardiac function is grade I-II, the safety of general anesthesia and surgery should be guaranteed, while grade IV is a high-risk patient, and the risk of anesthesia and surgery is great. Since the quantification of cardiac function classification is not enough, many relevant factors cannot be summarized, so multi-factor analysis should also be used for a comprehensive evaluation.
(ii) Cardiac risk index
et al. correlated the patient’s preoperative risk factors with the occurrence of cardiac comorbidities and outcomes during surgery, and expressed each factor as a score based on its degree of impact on outcomes, thus providing a preoperative assessment of perioperative patient risk, cardiac complications, and mortality. The multifactorial cardiac risk index scale proposed by et al. has a total of 9 items with a cumulative score of 53. Due to the simplicity and convenience of this classification it still has clinical reference value at present. Subsequently, a prospective study by Zeldin et al. confirmed the practical value of the multifactorial cardiac risk index and elucidated the correlation between cardiac function and cardiac risk factor scores on perioperative cardiac complications and mortality, which could have a greater prognostic value when assessed in combination. A cumulative score >13 is equivalent to clinical cardiac function class III, and anesthesia and surgical safety can be improved if adequate preoperative preparation is performed and cardiac function improves to class II or early class III. If the cumulative value exceeds 26 points, cardiac function class IV, anesthesia and surgery are bound to be more dangerous, and more than half of the patients who die in the perioperative period occur in this group. It is worth noting that 28 points out of the total value of 53 points may reduce the risk of anesthesia and surgery by proper preoperative preparation or by suspending surgery until the condition improves.
(iii) Electrocardiogram, exercise test and ambulatory electrocardiogram
Routine electrocardiograms in cardiac patients can be normal before surgery, for example, at least 15% of routine electrocardiograms at rest in coronary patients are in the normal range. However, most patients have different degrees of abnormalities, such as rhythm changes (atrial premature, ventricular premature or atrial fibrillation), conduction abnormalities and myocardial ischemic manifestations (flat or inverted T waves and ST-segment depression), which can not only serve as a basis for preoperative preparation and treatment, but also help in intraoperative and postoperative management and identification of ECG changes caused by metabolic and electrolyte disorders and other systemic pathologies.
2.Exercise test
Exercise increases heart rate, beat volume, myocardial contractility and blood pressure, causing an increase in myocardial oxygen demand. Therefore, it can be used as an estimate of the perioperative patient’s ability to tolerate the stress response. The product of maximum heart rate and systolic blood pressure (RPP) provides a rough response to the patient’s perioperative tolerance.
In the ECG plate exercise test, if a patient fails to achieve 85% of the maximum expected heart rate, significant ST-segment depression occurs, and the incidence of perioperative cardiac complications is as high as 24,3%. In contrast, patients who can exercise up to the expected fast heart rate without ST-segment changes have only a 6.6% chance of cardiac complications. The presence of ST-segment depression during ECG exercise testing reflects subendocardial myocardial ischemia, while ST-segment elevation indicates transmural myocardial ischemia or abnormal motion in the ventricular wall of the original myocardial infarction zone. A decrease in blood pressure often indicates the presence of severe heart disease and should be terminated immediately.
A positive exercise test ECG is classified as ST-segment depression greater than 1 mm with typical precordial pain or ST-segment depression greater than 2 mm, which can often help in the clinical diagnosis of coronary artery disease, but a negative test does not completely exclude the possibility of coronary artery disease, especially if there is a history of typical coronary artery disease. False positives often occur in patients with left ventricular hypertrophy, mitral valve prolapse, preexcitation syndrome, and digitalis drugs. Difficulties and false negatives can occur if the patient is unable to achieve the expected rapid heart rate, has poor exercise tolerance, has decreased blood pressure, and is taking beta-blockers. In addition, critically ill patients and vascular surgery patients have limited application due to inability to achieve the necessary amount of exercise.
3. Ambulatory electrocardiogram
Continuous ECG monitoring is not only used for preoperative 24-hour ambulatory electrograms to determine the presence of potential myocardial ischemia, heart rate changes and the presence of arrhythmias. It can also be used for intraoperative and postoperative continuous monitoring. It is generally considered that the sensitivity of this test for myocardial ischemia can reach 92%, specificity 88%, and negative prognostic value 99%, and it is more often used because it is non-invasive.
(iv) Echocardiography
Routine echocardiography can observe the acoustic reflection and two-dimensional graphics of the ventricular cavity when the heart is beating to understand the ventricular wall motion, myocardial contraction and ventricular wall thickness, the presence of ventricular wall tumor and incoordination during contraction, valve function, the degree of transvalvular pressure difference and left ventricular ejection fraction (LVEF). If LVEF is less than 35%, it often indicates poor cardiac function, higher incidence of perioperative myocardial infarction, and increased chance of congestive heart failure. The use of transesophageal ultrasound Doppler during the perioperative period allows dynamic and continuous monitoring of the above indicators, early detection of myocardial ischemia and cardiac insufficiency, and assessment of the surgical effect.
(E) Coronary angiography
Coronary angiography is the gold standard for determining coronary artery lesions, allowing observation of the precise anatomy of the coronary arteries and the location and extent of coronary atherosclerosis. Left ventriculography can also be performed to understand left ventricular systolic function, ejection fraction and left ventricular end-diastolic filling pressure.
Indications for coronary angiography are.
① Angina pectoris that is difficult to control with medication or severe angina attacks even at rest;
(2) Recent increase in angina symptoms;
(iii) Positive electrocardiogram on exercise test;
④Dipyridamole-thallium scintigraphy with reversible defects;
⑤ Abnormal echocardiographic stress test indicating ischemia. Coronary angiography can determine whether the patient needs coronary artery bypass surgery.
(VI) High-risk, intermediate-risk and low-risk patients
1.Risk analysis of condition
(1) High-risk
① Recent history of myocardial infarction (7-30 days after infarction) with severe or unstable angina pectoris;
(2) Decompensated congestive heart failure;
③Severe arrhythmias (third degree AV block, severe symptomatic arrhythmias, uncontrolled supraventricular tachycardia ventricular rate);
④Severe valvular lesions.
(2) Intermediate risk
① Angina pectoris is not severe;
②History of myocardial infarction;
③History of congestive heart failure or current compensated heart failure;
④Diabetes mellitus (requiring treatment).
(3)Low risk
①Old age;
②Electrocardiographic abnormalities (left ventricular hypertrophy, bundle branch conduction block, ST-T abnormalities);
③Non-sinus rhythm (atrial fibrillation);
④History of cerebrovascular accident;
(⑤) Uncontrolled hypertension.
2.Surgical risk analysis
(1) High-risk expected cardiac accident risk non-fatal heart attack, the incidence of cardiogenic death is greater than 5%. Such as
①Emergency major surgery for elderly patients ;
②Aortic or other large vessel surgery;
(iii) peripheral vascular surgery;
④Prolonged surgical operations with significant fluid and/or blood loss are expected.
(2) The incidence of intermediate risk cardiac accident risk is less than 5%. For example
①Carotid endarterectomy;
(ii) Head and neck surgery;
(3) Thoracic and intra-abdominal surgery;
④Orthopaedic surgery;
⑤Prostate surgery.
(3) The risk rate of low-risk cardiac accidents is less than 1%. Such as
①Endoscopic operation;
②Surface surgery;
(3) Cataract surgery;
④Breast surgery.
(vii) Guidelines for preoperative condition estimation of non-cardiac surgery for cardiac patients
1.Is it an emergency?
2.Whether coronary artery bypass surgery has been performed within 5 years?
3.Whether coronary artery angiography was performed within 2 years?
4.Are there any coronary syndromes or more obvious clinical risk factors? Including: unstable coronary artery disease, decompensated heart failure, arrhythmia or severe heart valve disease, elective surgery should be postponed and treated actively, and surgery should be performed after the condition improves.
5.Does the patient have moderate clinical risk factors?
6.Although there are moderate clinical risk factors, but the heart reserve function is still good, it is almost impossible to have heart attack or death.
7.No significant clinical risk factors and good cardiac reserve function, generally speaking, it is safe to perform non-cardiac surgery.
8.The results of noninvasive tests can determine whether surgery can be performed.
The above guidelines can help determine whether a high-risk patient should cancel or postpone surgery, or perform non-cardiac surgery followed by coronary artery bypass surgery or ICU admission.