Pregnancy myocardial infarction

Introduction to pregnancy-induced myocardial infarction Pregnancy myocardial infarction is a rare pregnancy complication, and there are few reports in China. This type of myocardial infarction is different from other types of myocardial infarction because it not only endangers the life of the pregnant woman, but also poses a threat to the fetus. basic knowledge The proportion of illness: 0.00035% Susceptible population: pregnant women Mode of infection: non-infectious Complications: edema

Causes of pregnancy-induced myocardial infarction

(1) Causes of the disease

1. There is a family history of positive family history of myocardial infarction before age 60, such as high blood lipids, hypertension, and a positive family history of diabetes.

2. Disease factors Various disorders of abnormal lipid metabolism, such as persistent or refractory hypertension, diabetes.

3. Bad factors smoking, alcohol abuse, drug abuse.

4. Environmental factors Women with type A personality and those with emotional instability and life stress.

5. Pregnancy-related disease factors Pregnancy and eclampsia, pregnancy with diabetes; pregnancy thromboembolic complications (occurring in thrombophlebitis, myocarditis, chronic atrial fibrillation, atrioventricular block, bacterial endocarditis, primary On the basis of sexual cardiomyopathy).

6. Insufficient female hormone secretion, female amenorrhea or artificial menopause, long-term oral contraceptives.

7. Other factors are congenital anomalies, such as abnormal coronary origin and aortic stenosis, coronary arteritis, hypertrophic cardiomyopathy, vasospasm, etc.

According to foreign reports, coronary angiography in patients with pregnancy complicated with myocardial infarction is often normal, presumably due to the reduction of coronary blood flow due to sputum or local thrombosis, the cause of convulsions is unclear, consider possible pregnancy with hypertension, or with oxytocin It is also a common cause of hormones and other factors related to pregnancy or postpartum coronary dissection.

(two) pathogenesis

1. Pathological changes of pregnancy-induced myocardial infarction Myocardial infarction is still dominated by coronary artery occlusion, and coronary occlusion is mostly based on coronary atherosclerosis. The pathological study on sudden cardiac death has the following four Important findings:

1 A large proportion of women dying is not caused by atherosclerotic heart disease.

2 The degree of coronary artery stenosis in women with sudden death is similar to that of men.

3 Compared with men of the same age, women with other causes have less arteriosclerosis.

4 The chances of acute pathological changes such as thrombosis occur in both sexes.

The main pathological changes of pregnancy myocardial infarction have the following aspects.

(1) severity of coronary atherosclerosis.

(2) acute pathological changes in coronary arteries (including thrombosis, coronary thromboembolism, intra-plaque hemorrhage).

(3) coronary vasospasm.

(4) Myocardial pathological changes (ischemia, injury, necrosis).

(5) Cardiac hypertrophy.

(6) Pathological changes of myocardial infarction caused by non-coronary atherosclerotic diseases.

It is worth mentioning that angiographic coronary artery in patients with gestational myocardial infarction may be normal. In the past 10 years, there is sufficient evidence to show that the pathological mechanism of this type of disease is caused by coronary artery spasm. When patients use ergot, they can often induce coronary spasm and reproduce the clinical manifestations of myocardial infarction. This situation is confusing in many literatures, so some cases are called X syndrome, coronary artery sputum (CAS), variation. Sexual angina pectoris, vasospasm heart syndrome, angina pectoris syndrome, etc., but the pregnancy myocardial infarction is completely different from the cause, but the cause and pathology may be the same as the cause of coronary artery spasm.

2. Pathophysiological pregnancy of myocardial infarction Pregnancy myocardial infarction is an important cause of maternal and child death caused by non-obstetric conditions during pregnancy, because the normal pregnancy process itself can bring many significant physiological changes, especially during childbirth. A change, some physiological changes during pregnancy mainly include the following aspects.

(1) Hemodynamic changes:

1 hemodynamic changes during pregnancy: hemodynamic changes including blood volume, cardiac output, stroke volume, heart rate, pulse pressure, oxygen consumption, these changes directly or indirectly affect myocardial perfusion and myocardial oxygen supply and demand Balance, myocardial ischemia and injury occur when local myocardial oxygen needs to exceed oxygen supply. If the supply and demand imbalance persists and the area of myocardial involvement is inevitably increased, myocardial cell death or myocardial infarction may occur.

The oxygen consumption of the myocardium is proportional to the increase in heart rate, myocardial contractility, and afterload (vascular resistance and blood pressure). Myocardial oxygen supply is mainly determined by the hemoglobin content and myocardial blood flow in the blood supply.

Myocardial perfusion mainly occurs in the diastolic phase; myocardial perfusion pressure is equivalent to diastolic blood pressure minus the specific ventricular preload pressure. Therefore, many myocardial infarctions including left ventricular infarction generally reduce pulmonary capillary wedge compression by diastolic blood pressure ( PC-WP can calculate myocardial perfusion pressure, so any pregnant woman with myocardial ischemia, especially myocardial infarction, should maximize oxygen supply and effectively reduce oxygen consumption.

The change of blood volume and cardiac output during pregnancy is the most important. The peripheral renal tubules increase the blood volume to 50% under the influence of aldosterone. At the same time, the red blood cell aggregation rate increases (about 18% to 25%), normal single pregnancy. In both, blood volume and cardiac output increased by 40% to 50%, and multiple pregnancies increased to 60% to 70%. When the mean arterial pressure did not change, the heart rate and stroke volume increased, and the systemic vascular resistance decreased. The change is directly related to the occurrence of gestational myocardial infarction, because the vast majority of ischemia occurs in the third phase of pregnancy (9 months, each period is 3 months) or before and after labor.

2 Hemodynamic changes during childbirth: The hemodynamic changes during childbirth are sharp and highly variable, depending on the position of the mode of delivery and the anesthesia method used.

A. The main changes in natural childbirth and vaginal birth time: blood volume can increase 300-500ml when the uterus contracts, cardiac output increases by 30%, heart rate can be slightly increased, unchanged or slowed down, so the stroke volume does not change. First, the blood pressure is increased, the first stage of systolic blood pressure can be increased by 4.7kPa (35mmHg), diastolic blood pressure is increased by 3.3kPa (25mmHg), and then gradually rises when entering the second stage of labor, starting to rise 5 to 8s before uterine contraction, when releasing Restoration, the peripheral resistance changes less.

B. Changes in cesarean section: The hemodynamic changes were not obvious directly in the operation. Only when the fetus and the placenta were removed, the cardiac output increased by 25%, and the heart rate did not change significantly.

C. Postpartum hemodynamic changes: postpartum hemodynamic changes are mainly affected by blood loss. The average blood loss during vaginal delivery is 500ml, and cesarean section is about 1000ml, but generally no adverse effects, followed by most of the early postpartum women. Have bradycardia (average reduction of 4 to 17 times / min), cardiac output increased by 10% to 80% (contracted uterine autologous blood transfusion and extracellular fluid absorption) can last from several days to several weeks (depending on renal function) .

(2) Hemorheological changes:

1 blood flow is slow:

A. Inflation of the uterus directly affects the blood return: directly compress the inferior vena cava in the supine position, so that the amount of blood returned to the heart is reduced and slowed down.

B. High expansion of pelvic vessels: blood flow is slow, a large amount of blood is injected into the internal iliac vein from the uterine vein, so it has resistance to the blood flow of the femoral vein to a certain extent. In the third trimester, the venous blood flow is reduced by half, and the venous pressure is increased. 1.3 kPa (10 mmHg).

2 The blood is in a hypercoagulable state:

A. Coagulation factors are increased compared with non-pregnancy: fibrinogen factor VII, VIII and other vitamin K-dependent factors are increased, especially in the third trimester of pregnancy.

B. Pregnancy with hypertension patients often have blood concentration, insufficient blood volume, increased blood and plasma viscosity, and more associated with hyperlipidemia, especially triglyceride and LDL content increased significantly, while HDL content decreased.

The above characteristics are mainly caused by high shear changes in blood rheology during pregnancy, which makes the blood in a state of hypercoagulability and hyperviscosity. This condition not only affects myocardial microcirculation perfusion, but also is prone to thromboembolism when there is damage in the blood vessels. The chance of non-pregnancy thrombosis is five times higher.

Thrombosis during pregnancy is also a major pathophysiological basis for gestational myocardial infarction.

Pregnancy myocardial infarction prevention

Before you get pregnant, you should do a related heart check, especially if you have a family history, alcohol or obesity.

Pregnancy myocardial infarction complications Complications edema

Systemic edema in pregnant women, dysfunction or rupture of the papillary muscles, rupture of the heart.

Symptoms of pregnancy-induced myocardial infarction Common symptoms Angina pectoris Myocardial infarction Chest pain edema

The clinical manifestations of pregnancy myocardial infarction have important reference and diagnostic value for diagnosis. The main clinical manifestations of pregnancy myocardial infarction are as follows.

Chest pain during pregnancy

Most of the chest pain that occurs during pregnancy is caused by pain in the anterior region or angina pectoris. It is often clinically easy to treat this pain with the lesions of the esophagus and/or digestive tract (gastric acid stimulation, pyloric spasm, ulcer disease). "burning heart" is confused, therefore, clinically, chest pain or angina pectoris should be screened during pregnancy, especially in emergency patients with sweating, body tightening, or persistent exacerbation of chest pain after general treatment, should be highly suspected of pregnancy Myocardial infarction.

2. Symptoms and signs that may be similar to normal pregnancy physiology

Pregnancy myocardial infarction due to the relationship between the number and location of myocardial infarction, many symptoms and signs that may be similar to normal pregnancy can be found in clinically observed symptoms and physical examinations, and need to be identified.

(1) Symptoms: Activity tolerance is reduced and breathing is difficult.

(2) signs: peripheral edema, jugular vein engorgement, apex beat ectopic.

(3) Cardiac auscultation: the first and second heart sounds of the split, the third heart sound (S3) gallop, the jet murmur on the left sternal border, the continuous murmur (from the breast vein murmur), non-pathological diastolic The murmur has reached 10%.

Examination of pregnancy-induced myocardial infarction

1. Increased serum myocardial enzymology

Significantly increased abnormalities such as CK, CK-MB, aspartate aminotransferase, and lactate dehydrogenase may occur, mainly due to the increased activity of CK isoenzyme (CK-MB).

2. ESR increases.

3. The patient may have blood lipids and the blood sugar concentration increases.

4. The chest X-ray left heart is straightened, the heart position is raised, and the blood vessels are obvious.

5. Electrocardiogram axis is left-biased, non-specific ST and T-wave changes, may have a typical pattern of myocardial infarction or a series of electrocardiogram evolution showing acute myocardial ischemia and necrosis.

6. Myocardial scintigraphy and some modern auxiliary examination diagnosis are helpful for the diagnosis of pregnancy myocardial infarction.

Diagnosis and diagnosis of pregnancy-induced myocardial infarction

diagnosis

According to the clinical symptoms and signs, the dynamic evolution of ECG and myocardial enzyme should be observed regularly to help early diagnosis and timely treatment, but the following points should be noted.

1. In normal pregnancy, there is often T wave inversion, 5% of pregnant women, III lead can have pathological Q wave, V2 lead R / S ratio increases, which is related to the elevation of the sputum during pregnancy, heart position changes.

2. In pregnancy toxemia, the activity of aspartate aminotransferase (AST) can also be increased.

3. At the time of delivery, depending on the mode of delivery, CKP-MB may also have different degrees of elevation, and the increase in cesarean section is greater than normal production.

Differential diagnosis

1. Identification of chest pain or angina during pregnancy

Sustained during pregnancy, and gradually increased chest pain, accompanied by sweating, chest "tightening" and "burning heart" feeling, the treatment should not be relieved should be highly suspected of myocardial infarction.

Chest pain during pregnancy, should promptly rule out gastrointestinal diseases, such as hyperacidity, "heartburn" caused by pyloric sputum, and sputum caused by increased abdominal pressure in the third trimester.

Of course, it is also necessary to distinguish between "X syndrome", "variant angina", "cardiovascular spasm syndrome" caused by paroxysmal chest pain.

2. Identification of certain clinical symptoms and signs during pregnancy

When pregnant women have jugular vein engorgement, sweating, pale, cold limbs, or other symptoms, such as bradycardia, hypotension, arrhythmia, especially patients with chest pain, should think of this disease Maybe, at this time, it needs to be differentiated from heart failure and other complications caused by some heart disease.

3. Electrocardiogram identification of pregnancy myocardial infarction

It is the most convenient and convenient method for diagnosing pregnancy-induced myocardial infarction. However, when reading and evaluating the electrocardiogram, attention should be paid to the physiological Q wave and normal T during normal pregnancy due to the increase in yaw, the position of the heart changes, and QIII and T waves may occur. Inversion, more common in late pregnancy, QIII accounted for about 5% of normal pregnant women, TV4 inverted accounted for about 8%, these are not caused by myocardial lesions, domestic Zhang Guofen reported that pregnancy can appear deep QIII, inverted TV3 and electric axis The phenomenon of shifting to the left, in addition, prone to functional arrhythmia during pregnancy, mainly pre-systolic and supraventricular paroxysmal tachycardia, should be identified at the time of diagnosis.

ECG changes in pregnant myocardial infarction are a series of QRS-ST-T evolution processes, so clinically, ECG changes should be screened for normal pregnancy.

4. Diagnosis and differential diagnosis of serum enzymology in pregnant patients with myocardial infarction

Serum enzymology diagnosis of pregnancy myocardial infarction should pay attention to the following points.

(1) Increased G0T activity during pregnancy and puerperal period contributes to the diagnosis of myocardial infarction: but this enzyme activity is also increased during pregnancy poisoning, indicating that the differential diagnosis of pre-eclampsia and hypertension or early kidney disease is helpful. The latter two have no combined pregnancy.

(2) Increased CK-MB activity has sensitive diagnostic value: However, during childbirth, CK-MB activity level is also different due to different delivery methods. CK-MB activity is higher than vaginal delivery. some.

(3) Detection of other enzymes also contribute to the diagnosis of myocardial infarction.

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