[Crisis event] Sudden myocardial ischemia and acute myocardial infarction during perianaesthesia

Three consecutive times to learn more about the exciting content of sudden myocardial ischemia and acute myocardial infarction during perianaesthesia 1.
The occurrence and harm of sudden myocardial ischemia and acute myocardial infarction during perianaesthesia ) The incidence rate in our country is showing a significant upward trend, and the number of patients with coronary heart disease among surgical patients has also increased correspondingly
.

Due to the influence of anesthesia, surgical trauma and other factors, patients with coronary heart disease may experience an imbalance between coronary blood supply and cardiac blood demand during the perianaesthetic period, resulting in coronary blood flow unable to meet the needs of myocardial metabolism, resulting in acute myocardial ischemia.
Oxygen (peri-anesthesia myocardial ischaemia) and even myocardial necrosis (peri-anesthesia myocardial infarction, PMI)
.

Because the surgical risk of such patients is significantly greater than that of ordinary patients, timely and effective diagnosis and treatment of peri-anaesthetic acute myocardial ischemia or myocardial infarction can significantly improve the prognosis of patients
.

Generally speaking, myocardial ischemia mainly occurs after surgery and is closely related to myocardial infarction (MI) and other cardiovascular complications
.

In contrast, intraoperative myocardial ischemia is relatively rare and rarely associated with the occurrence of myocardial infarction
.

Therefore, as far as anesthesia is concerned, whether it is general anesthesia or regional anesthesia, as long as there are no complications, it is not a risk factor for non-cardiac surgery in high-risk heart disease patients
.

On the contrary, anesthesia without complications can increase the threshold of myocardial ischemia
.

Surgical operations and postoperative stress during the perianaesthesia period are the main contributing factors to myocardial ischemia, infarction and cardiogenic death
.

Before the occurrence of perianaesthetic acute myocardial infarction, almost all patients have persistent (>100 minutes) ST-segment depression myocardial ischemia after operation, while ST-elevation myocardial infarction is relatively rare after operation
.

Most perianaesthetic acute myocardial infarctions occur in the first 24 to 48 hours after surgery, and most of the perianaesthetic acute myocardial infarctions lack obvious clinical symptoms.
The electrocardiogram generally shows no Q-wave myocardial infarction
.

The main difference between myocardial infarction in non-surgical patients and acute myocardial infarction during perianaesthesia is the location of myocardial infarction, the time and condition of the diagnosis of myocardial infarction
.

Most non-surgical patients with myocardial infarction occur outside the hospital.
Symptoms and signs of advanced myocardial infarction or myocardial infarction have already occurred when the patient goes to see a doctor.
Acute myocardial infarction during perianaesthesia occurs in the hospital, which can be predicted prospectively The possibility of acute myocardial infarction during the peri-anaesthetic period within a short period of time (1 to 5 days) after the operation
.

Therefore, for acute myocardial infarction during perianaesthesia, the patient is usually under close monitoring
.

Because ECG monitoring has unique advantages, continuous ECG monitoring should start before the start of anesthesia and continue for several hours or days after anesthesia
.

The 12-lead electrocardiogram continuous monitoring used today is supplemented by troponin measurement and other methods, so that there is a better correlation between myocardial ischemia and myocardial infarction during perianaesthesia
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For patients with coronary heart disease, especially those with hypertension or previous myocardial infarction, and those who have experienced rapid blood pressure fluctuations during the operation, the electrocardiogram should be monitored continuously after the operation, and a full-lead electrocardiogram should be taken once a day, and the same as the preoperative electrocardiogram Compare
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If symptoms of hypotension, dyspnea, cyanosis, tachycardia, arrhythmia or congestive heart failure occur suddenly after surgery, the possibility of acute myocardial infarction should be considered, and ECG and related serum enzymatic examinations should be performed immediately for early Diagnose and deal with it in time
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The hazards of myocardial ischemia and acute myocardial infarction during peri-anaesthesia are as follows: 1.
Myocardium is completely dependent on aerobic metabolism, and its intracellular oxygen and ATP storage is very small.
Once ischemia occurs, the myocardium quickly transforms from aerobic metabolism to anaerobic metabolism.
A large amount of lactic acid is produced, which lowers the pH in the cardiomyocytes, and then the ion pump malfunctions.
A large amount of Ca2+ enters the cell, destroys the cell membrane structure, and causes irreversible changes such as cell disintegration
.

2.
Myocardial ischemia can cause the contractile force to be weakened in a few seconds, and the ischemia can resume reperfusion in 1 to 5 minutes, and its contractile function can take several hours or even 24 hours to return to normal
.

If the ischemia> 20 minutes to restore reperfusion, the myocardium will not be able to fully recover and necrosis occurs in the central part of the ischemia, usually from the endocardium to the epicardium
.

3.
The adverse effect of myocardial ischemia on the body is that it interferes with the heart pumping function.
The first is the change of diastolic function.
The effect on ventricular compliance depends on the oxygen supply and consumption of the myocardium
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If the coronary blood flow is reduced by 80%, it can cause weak heart contractions
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When coronary blood flow is reduced by 95%, ventricular dysmotility occurs
.

4.
When myocardial ischemia is severe, abnormal hemodynamics can occur, leading to arrhythmia, pulmonary edema, myocardial infarction, shock and even cardiac arrest
.

2.
Analysis of causes of sudden myocardial ischemia and acute myocardial infarction during perianaesthesia 1.
Decreased myocardial oxygen supply (1) Decreased coronary blood flow
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① Coronary artery stenosis: Coronary atherosclerosis (the most important factor for the decline of coronary blood flow and an important cause of preoperative myocardial ischemia) and coronary artery spasm
.

② Decreased aortic diastolic blood pressure: When blood loss, excessive anesthesia and other factors lead to low blood pressure, decreased aortic diastolic blood pressure can cause insufficient myocardial perfusion and ischemia, especially in patients with aortic insufficiency
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③ Hypotension, aortic valve insufficiency
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④ Increased heart rate: too shallow anesthesia and insufficient blood volume, resulting in a decrease in myocardial perfusion, resulting in myocardial ischemia
.

⑤Reduced blood oxygen carrying capacity: decreased hemoglobin content, such as blood loss and anemia; abnormal dissociation curve of oxygenated hemoglobin, such as alkalosis; decreased blood oxygen saturation
.

(2) Decreased lung ventilation and/or lung ventilation function
.

2.
Increased myocardial oxygen demand (1) Increased heart rate, which is seen in shallow anesthesia, fever, pain, etc.
, can significantly increase myocardial oxygen demand, reduce myocardial oxygen supply, and induce myocardial ischemia
.

(2) Increase of ventricular wall tension: ①The increase of preload leads to the increase of ventricular volume and radius, and the corresponding increase of ventricular wall tension.
Myocardial contraction will consume more energy and oxygen, which is seen in perianaesthetic blood transfusion, excessive fluid transfusion, etc.
; ②After Increased load is common in high blood pressure.
In order to pump blood efficiently, the heart needs to consume more energy and oxygen
.

(3) Increased myocardial contractility, seen in the application of positive inotropic drugs, sympathetic-adrenal system excitement
.

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Coping strategies for sudden myocardial ischemia and acute myocardial infarction during perianaesthesia The treatment of ischemic heart disease (including myocardial infarction) is a comprehensive process, and the priority goal of its treatment is to prolong the life of the patient as much as possible
.

1.
Adequate preoperative preparation includes smoking cessation, low-fat, low-cholesterol diet to control weight, regular aerobic exercise, and effective control of high blood pressure, diabetes, obesity and hyperlipidemia
.

It should also correct anemia, hypotension, hypovolemia, acid-base and electrolyte imbalance, control heart rate, and give appropriate preoperative drugs.
In order to control the onset of angina pectoris, patients who are treated with β-receptor antagonists before surgery do not need to stop the drug
.

2.
Local anesthesia should be used for minor surface surgeries as the method of anesthesia: regional block anesthesia or intraspinal anesthesia can be used for limbs and lower abdomen surgery; intratracheal general anesthesia should be used for severe trauma and long time
.

During anesthesia surgery, sufficient oxygen is required to maintain stable circulation and avoid drastic changes in heart rate and blood pressure
.

3.
Try to eliminate the violent fluctuations of heart rate and blood pressure caused by cardiovascular stress during the induction of anesthesia.
Fentanyl, midazolam, propofol, and atracurium besilate should be used in a reasonable combination
.

Patients with poor cardiac function can switch to etomidate 0.
2~0.
3mg/kg
.

4.
Strengthen the management of anesthesia to maintain an appropriate depth of anesthesia during the operation, replenish blood volume in time, and maintain hemodynamic stability
.

Strengthen respiratory management to ensure unobstructed airway; prevent hypercapnia and hypocapnia; maintain blood gas within the normal range
.

5.
Drug therapy (1) β-receptor antagonists: the main drugs for the treatment of angina pectoris, commonly used pradalol, metoprolol, esmolol, labetalol, etc.
, these drugs can treat angina pectoris and slow down Heart rate, reduce myocardial oxygen consumption and increase coronary blood flow
.

If the dose is too large, it may inhibit myocardial contractility
.

Its contraindications include severe bradycardia, sick sinus syndrome, severe reactive airway disease, atrioventricular block, and uncontrolled congestive heart failure
.

The most common adverse reactions are fatigue and insomnia
.

(2) Calcium channel blockers: Verapamil is commonly used.
This type of drug has unique effects, slows down the heart rate, dilates the coronary arteries and prevents myocardial ischemia, and can also be used to treat hypertension
.

However, it is contraindicated in patients with severe congestive heart failure.
The common adverse reactions are hypotension, peripheral edema and pain
.

(3) Angiotensin converting enzyme inhibitors: commonly used captopril, captopril can dilate coronary arteries, increase blood flow, and lower blood pressure
.

Angiotensin-converting enzyme inhibitors are recommended for all patients with coronary artery disease, especially those with hypertension, left ventricular dysfunction or diabetes
.

Contraindications for angiotensin converting enzyme inhibitors include patients with drug intolerance or allergy, hyperkalemia, bilateral renal artery stenosis, and renal failure
.

(4) Nitroglycerin: Nitroglycerin has a dilation effect on the aorta and veins of the whole body, increases collateral circulation, reduces left ventricular end diastolic pressure and ventricular wall tension, reduces myocardial oxygen consumption, and facilitates coronary blood flow from the epicardium to the Endocardium, thereby improving blood supply to the full-thickness myocardium
.

It should be noted that when the systolic blood pressure is less than 90mmHg, the heart rate is less than 60 beats/min or greater than 100 beats/min, and those with low blood volume are forbidden
.

6.
Nerve block epidural analgesia pump, stellate ganglion block, etc.
can expand the coronary arteries, slow down the heart rate, reduce myocardial oxygen consumption, and relieve angina pectoris
.

7.
Interventional or surgical treatment of coronary thrombolysis or percutaneous transluminal coronary angioplasty
.

8.
Management of acute myocardial infarction Anesthesiologists should detect myocardial infarction as soon as possible.
Regular treatment includes immediate recanalization (including recanalization and revascularization), application of aspirin and β-receptor antagonists, calcium channel blockers, and left ventricle.
Angiotensin-converting enzyme inhibitors are contraindicated in patients with poor function
.

In patients with progressive myocardial infarction, aortic balloon counterpulsation (IABP) can increase coronary blood flow while reducing heart load
.

4.
Thinking of sudden myocardial ischemia and acute myocardial infarction during perianaesthesia.
Sudden myocardial ischemia and acute myocardial infarction during perianaesthesia are the main causes of death during perianaesthesia.
It is a great test for anesthesiologists
.

01 First of all, preoperative discovery, examination, treatment and risk assessment help to minimize the occurrence of complications and mortality during peri-anaesthesia.
Therefore, pre-anaesthesia doctors need to fully understand the patient’s physical condition and medical history, Fully understand the risk, actively communicate with the patient’s attending doctor and family members, improve the necessary pre-anaesthesia examinations, consult relevant departments if necessary, reduce preoperative risk factors, and make family members clearly aware of the peri-anaesthetic period Possible risks
.

02Secondly, β-receptor antagonists, nitrate drugs, calcium channel blockers, etc.
can be given as appropriate before anesthesia.
Dihydropyridines (especially short-acting nifedipine) drugs should be discontinued and replaced with other drugs
.

At the same time, prepare for emergency coronary angioplasty
.

03 Again, during anesthesia, try to choose local or regional block according to the needs of the operation, and ask a senior anesthesiologist to guide the anesthesia operation and medication, try to avoid bad irritation during anesthesia and severe circulatory fluctuations caused by poor control of anesthetics
.

During anesthesia, the occurrence of myocardial ischemia should be minimized (tachycardia, low diastolic blood pressure and high systolic blood pressure may all promote the occurrence of myocardial ischemia)
.

In addition to routine monitoring during the peri-anaesthesia period, monitoring of central venous pressure, invasive arterial pressure, urine output, etc.
should be considered for medium- and high-risk patients undergoing major surgery, and transesophageal echocardiographic monitoring can be performed if conditions permit
.

Routine blood examinations are performed during the operation to accurately supplement the blood loss and maintain sufficient hemoglobin content
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04Finally, at the end of the operation, if the patient is under general anesthesia, to ensure that the patient wakes up steadily, consider removing the tracheal tube under deep anesthesia or using short-acting β-receptor antagonists
.

Complete postoperative analgesia can avoid acute myocardial ischemia caused by circulatory and respiratory fluctuations caused by painful stimulation after painful awakening.
If necessary, it can be observed in the anesthesia recovery room until the patient is fully awakened
.

Before leaving the operating room, inform the intensive care center or ward care unit to prepare for receiving the patient.
At the same time, the anesthesiologist and itinerant nurse accompany the patient back to the ward and handover the shift at the bedside, and ask the patient's family members to take precautions after the operation
.

5.
Typical case sharing of sudden myocardial ischemia and acute myocardial infarction during perianaesthesia.
Patient, 72 years old, weight 70kg, was admitted to the hospital with "repeated left upper abdominal pain for 10 years and worsened for 2 months" and was diagnosed as "gastric ulcer" "It is planned to "subtotal gastrectomy" under general anesthesia
.

The patient had previous hypertension for more than 20 years and was controlled by oral aspirin, Dioxinxuekang, and Nitrendipine (the specific dose is unknown)
.

Preoperative blood pressure is well controlled, generally 140/70mmHg
.

Was diagnosed with coronary heart disease and old inferior myocardial infarction (the specific diagnosis and treatment content is unknown)
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After admission, the patient is generally in good condition, with moderate nutrition, active posture, and cooperation in physical examination
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Electrocardiogram: sinus rhythm, ST-T changes
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Echocardiogram: left ventricular ejection fraction 50%
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After entering the operating room, the patient sweated profusely, gave oxygen to the mask, quickly infused 500ml of colloidal fluid, measured blood pressure 65/45mmHg, SpO295%, lead II ECG showed sinus rhythm, and the heart rate was 52 beats per minute
.

10mg of ephedrine was given intravenously, the blood pressure rose to about 130mmHg, and the patient felt his symptoms relieved
.

Considering that the patient has a history of hypertension, coronary heart disease, and old myocardial infarction, he immediately requested a cardiology consultation
.

The ECG showed severe depression of the ST segment in leads V7, V8, AVL, and I, suggesting side wall and posterior myocardial infarction.
Immediately give 1 mg morphine, 100 mg dopamine and 500 ml normal saline, and 5 mg nitroglycerin plus 500 ml 0.
9% sodium chloride injection Intravenous drip
.

A few minutes later, the patient had sudden dyspnea, loss of consciousness, and respiratory arrest.
He immediately provided oxygen with a face mask and pressed the heart outside the chest
.

After 2 minutes, the patient's consciousness recovered, the blood pressure was 110/65mmHg, SpO297%, and he was quickly sent to the ICU, where he was diagnosed as acute lateral myocardial infarction, posterior myocardial infarction, and old inferior myocardial infarction
.

ECG monitoring indicated sinus arrest and junctional escape
.

Coronary angiography showed that the left main trunk was scattered in plaques; the anterior descending branch was diffused with plaques; the circumflex branch was diffused with plaques; the right coronary artery was diffused with plaques throughout
.

Conclusion: Three-vessel lesions involve the left main, circumflex, and right main coronary arteries
.

Emergency coronary stenting
.

The patient recovered well after the operation
.

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