Heart-to-heart heart transplantation

Heterotopic heart transplantation is also called side-by-side heart transplantation. The heart is transplanted into the right thoracic cavity of the recipient, and the heart of the recipient is not removed. The heart of the donor and recipient remains the cyclic function. Since Barnard was successfully applied in clinical practice in November 1974, the advantages of ectopic heart transplantation are: 1 When the heart is experiencing acute rejection, the original recipient heart can maintain the patient's life and wait for a heart transplant again. 2 If the donor heart is too small for in situ heart transplantation, it can be used for ectopic transplantation. 3 for patients with pulmonary hypertension and high pulmonary vascular resistance. The disadvantages of ectopic heart transplantation are: 1 It is difficult to perform endocardial biopsy. 2 easy to form a thrombus in the heart cavity. 3 The operation time is long and the operation is complicated. 4 The right pleural cavity of the recipient is built into a donor heart, affecting the right lower lobe ventilatory function of the recipient.

Treatment of diseases: heart valve disease, heart failure, congenital heart disease, cardiomyopathy, coronary heart disease

Indication

Whole heart side-by-side heart transplantation is available for:

Cardiac transplantation is suitable for patients with ineffective medical treatment, refractory heart failure, end-stage heart disease with or without malignant arrhythmia, and no irreversible damage to other organs. The heart function is grade IV and the expected survival time is <12 months. Early heart transplants require patients under the age of 55, and have now expanded their age range, from infants up to 1 year of age to 70 years of age.

1. Cardiomyopathy A variety of cardiomyopathy includes dilated cardiomyopathy, chronic Keshan disease, and restrictive cardiomyopathy. About 50% of all cases are the main indication for heart transplantation.

2. Coronary heart disease is a major feature of ischemic cardiomyopathy due to severe multiple coronary artery disease or extensive myocardial infarction caused by refractory heart failure and arrhythmia, accounting for about 40% of heart transplantation.

3. Valvular heart disease with valvular lesions of extensive myocardial lesions and myocardial intimal fibrosis, accounting for about 4% of heart transplants. For patients with pulmonary hypertension, cardiopulmonary transplantation may be considered.

4. Congenital heart disease such as congenital left ventricular dysplasia syndrome, complex single ventricle with subaortic stenosis.

5. Other cardiac tumor patients who cannot be removed by surgery and those who need re-transplantation of the heart.

Contraindications

1. Acute severe infectious diseases such as purulent infection, sepsis, septic shock, active hepatitis, tuberculosis and various parasitic infections.

2. Pulmonary hypertension pulmonary arteriolar resistance > 8 woodU, mean pulmonary artery pressure > 60 mmHg.

3. Insulin dependent diabetes.

4. Malignant tumors cause tumors to deteriorate due to the use of anti-rejection drugs after surgery.

5. Severe systemic connective tissue diseases: such as systemic lupus erythematosus, progressive systemic scleroderma, amyloidosis, etc.

6. Irreversible changes occur in important organs such as liver, kidney and brain.

7. Active digestive ulcer disease.

8. Drug abusers.

9. Mental illness and disobedience to the treatment.

Preoperative preparation

Donor selection

The donor heart is generally taken from the brain dead. The main feature of brain death is deep coma; brainstem reflex completely disappears; there is no spontaneous respiration, and the state of "brain death" caused by deep hypothermia or central nervous suppression drugs needs to be excluded, which is recognized by internal medicine and neurologists. The donor age is generally considered to be less than 35 years for men and less than 40 years for women. However, as the demand for donors continues to increase, the current age range is gradually relaxed. The size of the donor should be appropriate, and the clinical evaluation is mainly based on the weight ratio of the donor/receptor. It is currently considered that the difference in body weight of adult heart transplants should not exceed ± 20%, but the matching parameters for infants and children can be relaxed. The gender requirements for choosing a heart are generally less well documented, but in some gender-related retrospective studies, certain phenomena and perspectives are worth mentioning. Crandall et al. retrospective analysis of 140 consecutive heart transplant patients found that acute rejection of female patients occurred earlier and more frequently. They believe that the high incidence of rejection after heart transplantation in women is due to the mismatch of HY antigens. The HY antigen is distributed on the cell membrane of male tissues. It determines the sex differentiation of the gonads. Female cells do not have such antigens. When male tissue cells are implanted into women, the immune function of women is activated and an immune response occurs. Therefore, if a female patient is selected for surgery, the donor should also be a female.

Systemic conditions of the donor should exclude infectious diseases, no hypertension, diabetes, and malignant tumors. The donor should have no history of heart disease and a history of chest trauma that may involve the heart, and no history of severe hypotension or cardiac arrest. X-ray chest radiography and electrocardiogram examination should be performed before surgery. The donor ABO blood type must be matched to the recipient, and the positive rate of lymphocyte toxicity is <10%. Pay attention to the compatibility of histocompatillility antigens (HLA). At present, the degree of coordination of class I antigens is known to be related to the long-term survival of transplanted organs; the degree of complexation of class II antigens is closely related to recent survival, while the most affected type I antigens are A and B sites, and class II antigens are DR sites. In considering HLA matching, striving to find one or more donors and receptors with the same antigen specificity at A, B and DR sites can lay a foundation for reducing rejection after transplantation.

Preoperative preparation

(1) Preparation of the recipient: comprehensively understand the medical history data, detailed physical examination and a series of auxiliary examinations, including blood, urine and stool routines; blood biochemistry, liver and kidney function, lung function, gastrointestinal tract tincture Perspective, bacterial culture of throat swabs, sputum, and urine. To carry out tuberculin test, serum E cell inclusion body virus, toxoplasma, HIV, Epstein-Barr virus and hepatitis virus tests. Blood type identification, lymphocyte toxicity cross test and HLA typing are also performed. For those with severe heart failure symptoms, medical treatment should be actively carried out to improve the overall condition. For patients with severe heart failure whose drug cannot be controlled, intra-aortic balloon counterpulsation should be performed, or mechanical aids should be considered to temporarily improve the function of the organ and create conditions for heart transplantation.

For the heart to take and the artificial heart-lung machine to install the artificial heart-lung machine time to connect well, in the distance to take the heart to use the cordless phone to communicate with each other, it is expected that the heart will be pushed to the operating room 2 hours before the arrival of the heart, prepare and establish extracorporeal circulation, waiting for heart.

(2) for the heart to take: usually the multi-disciplinary physicians cooperate, to see the same or the same as the urologist. Take the supine position, routine iodine disinfection of the chest and abdomen skin, and systemic heparinization of 3mg / kg, to prevent thrombosis in the small blood vessels. Take the midline incision in the chest, cut the happy bag, and immediately check for heart trauma, deformity or heart disease. The ascending aorta was rapidly released to the beginning of the innominate artery, the superior vena cava was freed to the pericardial reentry, and the superior vena cava was ligated about 4 cm above the junction of the superior vena cava and the right atrium. The aorta and pulmonary artery were isolated and a cold irrigation needle was inserted into the ascending aorta root. A vascular clamp was used to clamp the inferior vena cava. After about 3 to 4 heart beats, the ascending aorta was blocked by the near-named artery, and the cold cardioplegia was perfused. 10 mmol of potassium chloride was added per liter of the cardioplegia. Ensure that the heart is stopped in a diastolic state, the perfusion is generally 1 000 ml, and the perfusion pressure is maintained at 40-80 mmHg. Immediately at the beginning of perfusion of cardiac arrest, the right superior pulmonary vein and inferior vena cava should be cut open to prevent the heart from expanding. At the same time, ice physiological saline is placed in the pericardial cavity for local cooling. The heart cooling takes about 2 minutes. The superior and inferior vena cava are cut off at the distal side of the ligation. The ascending aorta is cut off under the aortic occlusion forceps, and the pulmonary artery is cut from the left and right pulmonary bifurcations. The right and left upper and lower pulmonary veins are respectively cut at the pericardial reflex, and the surrounding tissue of the left atrium wall and the superior vena cava entrance is bluntly stripped, and the heart can be completely removed. It is placed in a double-layer plastic bag containing ice-cold saline, double-ligated, placed in a sterile saline container, sealed in a plastic bucket and transported. If the distance is long, the ascending aortic perfusion needle can be connected to the infusion tube, ready for perfusion of cold stop fluid, and the whole process must be absolutely sterile.

There is a myocardial ischemia process in the heart, and the cold infusion from the brain death to the donor blocking the ascending aorta is a warm ischemia time, which should be shortened as much as possible (<3~5min). The cold ischemia time is from the beginning of cold irrigation to the completion of transplantation and ascending aorta obstruction. It is generally considered that the longest time for heart tolerate ischemia is 3 to 4 hours. If the heart transplantation operation time is reserved for 1 hour, then Shipping time on the road should be limited to 2 to 2.5 hours. If the distance is too far, or the transportation is not convenient, a flexible way is to contact the conditional hospital in the donor area, and the surgical group takes the receptor to the hospital near the heart area to ensure safety.

Surgical procedure

1. Heart cutting and repair

The aorta is dissected to the descending aorta and the head arm branches are ligated. The superior vena cava is freed to the entrance of the innominate vein, and the rest of the operation is roughly the same as the in situ heart transplantation. After removing the heart, the opening of the two pulmonary veins and the inferior vena cava on the right side was closed with a 5-0 polypropylene suture. The tissue between the left and right pulmonary veins is then excised to form an opening into the left atrium, with an opening diameter of 3.5 to 4 cm. Finally, a longitudinal incision of about 5 cm was made on the right posterior side of the superior vena cava and the right atrium.

2. Implantation of the donor heart

Put the heart into the right chest, located in front of the right lung and next to the recipient's heart, to prevent the heart from rotating or twisting. In the rear cushion of the heart, soak the 4 °C cold salt water gauze pad, and then supply the heart to the same level of the heart to facilitate the fit.

(1) Anastomosis of the left atrium: the left atrium is cut behind the recipient's chamber ditch, from the left to the left, down to the left, using the 4-0 polypropylene line first in the recipient's left atrium and the left atrium. The midpoint of the margin was sutured and ligated, and the continuous suture was performed in the upward and inferior directions. Finally, the anterior middle part merged and ligated to complete the anastomosis of the left atrium.

(2) anastomosis of the right atrium: the recipient's heart is made a longitudinal incision at the junction of the superior vena cava and the right atrium, and the incision is 2 to 3 cm from the superior vena cava and the right atrial wall. The midpoint of the posterior margin of the right atrium of the recipient was sutured to the lower end of the right atrial incision and ligated. Then the anastomosis was performed in the upward and inferior directions by continuous suture, and the leading edge of the two right atrial incisions was directly reached. Cooley proposed not to do the right atrial anastomosis of the two hearts, with the donor superior vena cava and the recipient superior vena cava for end-to-side anastomosis, the donor's inferior vena cava closed, can be studied.

(3) aortic, pulmonary anastomosis: a longitudinal incision in the appropriate part of the right aortic wall of the recipient, with 4-0 polypropylene suture for the donor, end-to-side anastomosis of the cardiac aorta. Because the pulmonary artery is not long enough, a pulmonary artery anastomosis is needed. A artificial blood vessel is added. One end of the artificial blood vessel is sewn on the heart-lung artery, and the other end is end-to-side anastomosis with the recipient pulmonary artery.