What Is an Aortic Root Replacement?

Aortic arch replacement is a relatively complicated operation with a high risk of surgery and a high mortality rate.

Aortic arch replacement

Aortic arch replacement is a relatively complicated operation with a high risk of surgery and a high mortality rate.

Chinese name

Aortic arch replacement

Foreign name

Aortic Arch Replacement

Alias

Aortic arch replacement

Classification

Cardiovascular Surgery / Thoracic Aortic Aneurysm Surgery

ICD encoding

38.4504

Aortic arch replacement

Surgical treatment of aortic arch aneurysms is a relatively complicated operation, with a high risk of surgery and a high mortality rate. In 1957, DeBakey successfully used the same type of aorta to replace the ascending aorta and aortic arch under cardiopulmonary bypass for the first time, and the brain was protected by innominate and left common carotid arteries. In 1975, Griepp et al. Applied deep hypothermia (esophageal temperature of 10 to 15 ° C) to stop circulation to treat aortic arch tumors, simplifying the operation method. In 1980, Crawford et al. Adopted the technique of intragraft anastomosis (graft inclusion technique) to match the three branches of the aortic arch with the artificial blood vessel, effectively solving the problem of bleeding or hemostasis. In 1981, Cooley et al. Routinely used deep hypothermia and open distal anastomosis techniques for type I dissection aneurysms. In 1983, Bort et al. Used the elephant trunk technique when surgically replacing aortic arch tumors. In 1990, Veda and others applied deep hypothermia circulatory arrest and continuous superior vena cava retrograde cerebral perfusion technique, which effectively prolonged the circulatory arrest time and has become one of the commonly used methods.

The most common surgical indications for aortic arch aneurysms are type I and type II aortic dissections, followed by ascending aortic aneurysms and arch aneurysms due to cystic degeneration of the aortic wall and atherosclerosis. Simple arch cystic or pseudoaneurysms are rare. It is generally considered that symptomatic aortic arch tumors, ascending aorta and arch tumors with aortic valve disease, and type and type aortic dissection are the main indications for aortic arch replacement. The purpose of aortic arch replacement is to prevent aneurysm rupture and to restore normal blood flow to the blood-supplying arteries in the brain.

Similar to ascending aortic replacement, patients with a history of stroke before surgery are not contraindications to surgery, but significantly increase the incidence of postoperative brain complications. Acute ascending aortic dissection with hemiplegia is not a contraindication for emergency surgery.

Elderly, arteriosclerotic aneurysms, those with a previous history of stroke, etc., it is best to do cerebral angiography before surgery, except for intracranial aneurysms. At the same time for patients with suspected coronary heart disease or age 40 years old, it is best to routinely perform coronary angiography.

Incision

Using a sternal midline incision, such as a large arch tumor or a proximal branch vessel involvement, the incision can be extended to the left neck appropriately.

Reveal

After opening the sternum with a swing saw, first separate the sternum and tissues, gradually open the sternum, free the innominate veins, separate the innominate artery, the left common carotid artery, and the proximal branch of the left subclavian artery. While maintaining the integrity of the mediastinal pleura, Free the lower and upper edges of the distal arch tumor, while paying attention to prevent damage to the left vagus nerve and recurrent laryngeal nerve, the umbilical cord can be used to pull the nerve. Until free to the proximal descending aorta or aortic isthmus. If the tumor is large, it can dissociate during the parallel cycle cooling.

3. Establish extracorporeal circulation and myocardial protection

Do femoral intubation and inferior vena cava intubation. Extracorporeal circulation was established and a left heart decompression tube was placed through the right upper pulmonary vein. The first dose of cardioplegia was infused directly through the aortic root or the left and right coronary arteries, and then switched to continuous perfusion of cold-blooded cardioplegia through the coronary sinus.

4. Methods of brain protection

One of the key factors for the success of aortic arch tumor surgery is effective brain protection, which is also the most important factor affecting the popularity of arch tumor surgery. There are three main clinically applied methods:

(1) Deep hypothermia circulatory stopping technique: that is, deep hypothermia is used for brain protection. When the central temperature (anal temperature or bladder temperature) is 15-20 ° C, the safety time of stopping the circulation is 40-50 minutes, exceeding 60 minutes, which will cause obvious postoperative brain damage. Generally, the EEG activity disappears when the circulation is stopped, or the internal jugular vein blood oxygen saturation is above 90%. Due to the limited stopping time, this method is not suitable for complicated arch aneurysm surgery.

Operation method: After the general anesthesia is successfully intubated, the anus temperature or bladder temperature probe and the esophageal temperature probe are placed. Establish extracorporeal circulation, parallel circulation to cool down, at the same time, put an ice cap on the head to cool down and use a cooling felt to cool the surface. During the cooling, the difference between blood temperature and central temperature should not exceed 10 ° C. During the cooling period, the tumors were separated and the proximal branches of the 3 branch vessels were detached, and the branch vessel bands were preset.

For simultaneous aortic valve replacement or ascending aortic replacement, or Bentall surgery, or other intracardiac surgery, the ascending aorta can be blocked and the cardiac arrest solution can be perfused when the temperature drops to 28-33 ° C. The above-mentioned operation is performed after cardiac arrest. Generally, there is sufficient time to complete the above-mentioned operation before the temperature is reduced to 15-20 ° C, which can save the operation time.

When the central temperature drops to 15-20 ° C, it is best to continue to maintain the blood temperature at that time and continue to cool for 10-15 minutes to ensure that the brain tissue and other tissues in the body are evenly cooled.

When the cooling requirement is reached, the head is lowered by 30 °, and the extracorporeal circulation is gradually stopped. At the same time, the venous reflux blood is increased by 1000 to 1500 ml. Then stop the circulation, tighten the branch vessels of the arch or block the 3 branch vessels of the arch with pliers to prevent air from entering the cerebral vessels. Loosen the aortic blocking forceps, make a longitudinal incision of the arch tumor, drain the blood from the tumor, check the proximal and descending aortic lesions, and perform half-arch replacement according to the nature, scope and type of the aortic arch lesions. Total arch replacement, or "elephant nose" surgery.

After the operation of the arch tumor was completed, blood was exhausted through the femoral artery cannula. After sufficient blood overflowed from the proximal port of the artificial blood vessel, the proximal end of the artificial blood vessel was blocked. The artificial blood vessel was inserted into the exhaust needle and the arch was opened. Three branches of blood vessels gradually returned to systemic perfusion and rewarming. During the rewarming period, the anastomosis of the distal and proximal vascular prostheses was completed, or the intracardiac operation or the proximal Bentall operation that was not completed before the stop cycle was completed.

During rewarming, the temperature difference between blood temperature and tissue should not exceed 10 ° C. Generally, the cooling time is about 45min, the rewarming time is about 60min, and the rewarming can be stopped when the anal temperature is 35 ° C.

To enhance brain protection during cessation of circulation, methylprednisolone (7 mg / kg) and sodium thiopental (7-15 mg / kg) can be applied before cessation of circulation. During the cooling and rewarming period, blood glucose should be monitored at all times. Insulin should be used to maintain blood glucose below 11.1mmol / L to prevent cerebral edema, and pay attention to potassium supplementation.

(2) Deep hypothermia circulatory retrograde cerebral perfusion technique: After deep hypothermia circulatory arrest, the arch aneurysm is incised, and the inferior vena cava is intubated for retrograde perfusion. This method can maintain a certain blood flow perfusion of the brain tissue during the cessation of circulation. Therefore, the safety time of stopping circulation can reach 90min, and the brain protection effect is obviously better than that of simple deep hypothermia stopping circulation. It is suitable for various complicated arch tumor surgery and is currently the most commonly used method.

Operation method: The basic operation method is similar to the deep low temperature stop cycle. When establishing extracorporeal circulation, another channel should be placed between the arterial supply vessel and the superior vena cava drainage tube in a Y-shaped connection for retrograde perfusion of the superior vena cava during the cessation of circulation. The requirements for cooling and rewarming are the same as those for the deep hypothermia stop cycle. After the stop cycle, the head is 30 ° low, the upper vena cava tube is clamped, and the arterial end returns blood to about 1000-1500ml. Intravenous perfusion of the superior vena cava, but the pressure of the right internal jugular vein must be less than 25-30 mmHg. The excessive pressure of the internal jugular vein may cause cerebral edema. During the operation, dark red blood flow was observed in the innominate artery and the left common carotid artery. The amount of blood flow was closely related to the perfusion flow. Generally, the perfusion flow of the superior vena cava is 250-500ml / min.

When the distal end of the arch aneurysm has been processed, and its three branch vessels have also coincided with the artificial blood vessel, the superior vena cava is reversely perfused, and the femoral artery tube blocking forceps are slowly released. gas. When blood overflows from the proximal end of the artificial blood vessel, clamp the Y-shaped tube, loosen the drainage tubes of the superior and inferior vena cava, and close the artificial blood vessel close to the proximal end of the innominate artery. At this time, the perfusion flow of the femoral artery can be gradually restored to the conventional extracorporeal circulation, and the temperature can be rewarmed in parallel while the head is raised to the normal position. In the rewarming phase, the intracardiac operation or the aortic root operation can be further completed. After the operation, the aortic blocking forceps placed on the artificial blood vessel are opened, and the heart is vented.

(3) Selective cerebral perfusion technique: Surgical treatment of aortic arch tumor with selective cerebral perfusion technique was the first successful application of DeBakey in 1957, but he was intubated with 3 or 2 branch blood vessels at that time for normal temperature blood perfusion. Arch replacement is performed after the descending aorta and the proximal ascending aorta. This technique requires multiple perfusion pumps, and branch blood vessels are intubated prone to postoperative brain complications. Therefore, there are not many clinical applications in the future, especially after clinical application of deep hypothermia circulatory arrest, only a few surgeons use this method. In the late 1980s, many scholars applied cold blood at 15-20 ° C to infuse the innominate artery and left common carotid artery during the deep hypothermic circulatory arrest at a flow rate of 300-800ml / min, which has achieved satisfactory results in clinical applications. It is important that the safe time for brain protection is significantly longer than the two techniques described above, and the incidence of postoperative brain complications has not increased significantly. Recently, according to the function of the Willis ring at the base of the brain, some authors only perfuse the innominate artery, and blood flow through the Willis ring to protect the left brain, which has also achieved good clinical results.

Operation method: femoral artery intubation and superior and inferior vena cava intubation to establish extracorporeal circulation, which can be cooled to anal temperature of 28-30 ° C in parallel, which can block the ascending aorta. Or the coronary artery opening is directly perfused with cardiac arrest solution. After cardiac arrest, the continuous myocardial coronary sinus reverse perfusion is used to protect the heart muscle. At this point, the temperature continues to decrease, while intracardiac surgery or proximal aorta surgery is feasible.

Insert an infusion tube with a balloon into the innominate artery and the left common carotid artery. When the temperature drops to 15-20 ° C, the circulation is stopped. The balloon of the innominate artery and the left common carotid artery is infused with normal saline to block blood flow. Another blood pump perfusions the above two perfusion tubes to provide blood flow to the brain. The flow rate is 10 to 15 ml / (kg · min), and the pressure of the right radial artery is maintained to 50 to 70 mmHg. At the same time, the left subclavian artery was blocked. The arch tumor was cut open, and a full arch or "elephant nose" operation was performed according to the condition of the lesion. After the distal anastomosis was completed, the left subclavian artery band and the airbag of the nameless, left common carotid perfusion tube were released, and the distal ventilation was performed. After fully venting, clamp the proximal end of the artificial blood vessel to stop the cerebral perfusion, restore the femoral artery perfusion and systemic extracorporeal circulation, and gradually warm up. The anastomosis of the proximal and distal vascular prostheses was completed during rewarming.

5. Replacement of the aortic arch

The method of aortic arch aneurysm resection and vascular prosthesis replacement should be based on the nature of the arch aneurysm, the extent and extent of the lesion, and for those who have no surgical experience, it is advisable to start with simple arch replacement and gradually transition to complex Arch surgery. There are currently three types of commonly used surgical techniques:

(1) Hemiarch replacement: It is mainly applicable to patients with ascending aortic aneurysms involving the proximal part of the arch, type or type acute dissection, or critically ill patients who are not suitable for total arch replacement.

Surgery method: Simple deep hypothermia circulatory arrest or deep hypothermia circulatory retrograde cerebral perfusion technique. During the cooling period, free the upper and lower edges of the aortic arch and the anterior wall to the descending aortic isthmus, pay attention to protect the vagus and recurrent laryngeal nerves, or complete the proximal Bentall operation during the cooling period. When the temperature of the anus is reduced to 15-20 ° C, the circulation is stopped or retrograde perfusion of the superior vena cava is added, and the tumor is cut longitudinally to preserve the large curved side of the arch, that is, the aortic wall of the 3 branch vessels. The small curved side is cut to the descending part to make the aortic arch look like a duck tongue. Suture the posterior wall with 3-0 or 4-0 polypropylene suture continuously and then suture the anterior wall continuously. If the aortic wall is poorly structured, apply a felt strip. Reinforced anastomosis can effectively prevent postoperative bleeding or bleeding.

Another surgical technique is to cut the tumor wall longitudinally without removing the tumor wall and perform continuous intraluminal anastomosis. After surgery, the tumor wall is trimmed and sutured to surround the anastomosis, which can effectively prevent bleeding and bleeding.

(2) Total arch replacement: Applicable to ascending aorta and arch true aneurysms, type or dissection of the artery, also applicable to simple arch aneurysms.

Surgical method: Due to the long operation time of total arch replacement, deep hypothermia circulatory retrograde cerebral perfusion or selective cerebral perfusion technique should generally be used.

First, during the cooling period, free arch tumors descend to the descending aortic isthmus to protect the vagus nerve and recurrent laryngeal nerve. During the aortic valve replacement or Bentall surgery and so on.

The temperature was lowered to 15-20 ° C, and the circulation was stopped. Retrograde cerebral perfusion was performed through the superior vena cava or selective cerebral perfusion was performed through the innominate artery and the left common carotid artery. The aneurysm was incised longitudinally.

Trim the arch tumor, but retain the lower and posterior walls of the tumor, select the appropriate vascular prosthesis, and use 3-0 or 4-0 polypropylene suture to close the descending aortic opening, and then suture the arch to contain 3 branch vessels The posterior wall of the opening, and finally the anterior wall are sutured continuously. After the operation, the femoral artery is perfused and ventilated. At this time, full attention should be paid to the venting of the arch branches, and the superior vena cava reverse irrigation or selective cerebral perfusion should be stopped. After full venting, clamp the vascular prosthesis. Finally, the artificial blood vessel is anastomosed with the proximal end of the ascending aorta, the artificial blood vessel is vented, and the blocking forceps are opened. If there is no bleeding or bleeding in each anastomosis, the tumor wall can be cut off; otherwise, the tumor can be wrapped with the tumor to achieve the purpose of hemostasis.

(3) "Elephant Nose" Surgery: Applicable to extensive aneurysms involving the ascending aorta, arch and descending aorta, or type III dissection combined with ascending aorta and arch aneurysm, can also be used for acute type I dissection. The main purpose of the elephant trunk surgery is to use the artificial blood vessels that are placed in the cavity of the descending aorta when the descending aortic aneurysm is performed at a later stage to facilitate the anastomosis of the descending aorta. In addition, for patients with type or type acute dissection, elephant trunk surgery can use a vascular prosthesis placed in the descending aorta cavity to isolate or block the dissection breach located near the descending aorta, or even To achieve the complete cure of type or acute dissection.

Surgical method: Deep hypothermia circulatory retrograde cerebral perfusion or selective cerebral perfusion technique must be applied to avoid serious damage to brain tissue due to long operation time. After stopping the circulation, the tumor was cut longitudinally to the proximal end of the descending aorta for retrograde or selective cerebral perfusion. According to the diameter of the descending aorta measured during the operation, an appropriate artificial blood vessel is selected, and the artificial blood vessel is placed in the cavity of the descending aorta according to the method shown in Figures 6.50.6-9A to C. It should be noted that the artificial blood vessel indwelling in the descending aorta cavity should not be too long, generally about 10cm, so as not to affect the intercostal artery blood supply and cause serious complications of paraplegia.

Use 3-0 or 4-0 polypropylene suture to continuously suture the vascular graft and descending aorta. At this time, prevent vagus and recurrent laryngeal nerve injury. After the anastomosis is completed, the proximal vascular prosthesis that is nested in the lumen of the distal vascular prosthesis is pulled out. At the opening of the vascular prosthesis corresponding to the 3 branch blood vessels of the arch, the upper part of the vascular prosthesis is cut out in a sheet shape, and the whole arch is cut according to the foregoing The replacement method completes the anastomosis of the arch branches. At this time, another arterial infusion tube must be inserted into the vascular prosthesis of the near-innocent artery, or the arterial supply vessel can be connected as shown in Figure 6.50.6-9F. After the femoral artery is perfused and ventilated, the vascular graft is clamped, and the superior vena cava reverse perfusion or selective cerebral perfusion is stopped. The arterial supply vessel connected to the artificial blood vessel is used to restore normal extracorporeal circulation and continue to warm up. Finally, the artificial blood vessel is anastomosed with the proximal aorta, the artificial blood vessel is inserted into the exhaust needle, the blocking forceps are opened, and the heart is vented. After protamine neutralizes heparin, if there is still bleeding at the anastomosis, the residual tumor wall can be wrapped around the artificial blood vessel to achieve the purpose of complete hemostasis.

1. Choose the right brain protection method

There are currently three methods of brain protection: simple deep hypothermia circulatory arrest, deep hypothermia circulatory arrest, retrograde cerebral perfusion, and selective cerebral perfusion. There are obvious differences between the three methods of stopping the safety time. For non-aortic dissections or those undergoing only half arch replacement, simple deep hypothermia can be used. For aortic dissections or those requiring total arch replacement or "elephant nose" surgery, the latter two methods should be used.

2. Choose the right surgical method

For patients with acute type aortic dissection, only ascending aortic replacement or half arch replacement can be performed, but those who are skilled or have better general conditions of the patient can perform full arch replacement or "elephant nose" surgery.

3. Protect the vagus and recurrent laryngeal nerves

When freeing the distal aortic arch, the vagus and recurrent laryngeal nerves should be carefully confirmed, and the nerves should be released first and then placed with a traction band. Special attention should be paid to preventing damage to the recurrent laryngeal nerve when the distal end of the lower edge of the arch is free.

4. Prevention and treatment of anastomotic bleeding

This is one of the key factors for successful surgery. At present, the intraluminal anastomosis technique is generally used, so it is not necessary to widely dissociate the aortic arch tumor, mainly to expose the 3 branch vessels and the lower edge of the arch. This can avoid the bleeding of the wound caused by extensive dissociation, and at the same time, the residual can be used after the anastomosis. The tumor wall surrounds the artificial blood vessel and the anastomosis, and plays a role of compressing and stopping bleeding. During anastomosis, the needle pitch is uniform, and the margin is at least 5mm. If the tumor wall is thin or fragile, the outer or inner membrane should be reinforced with a felt strip. Before stopping extracorporeal circulation, at least the appropriate amount of liquid should be ultra-filtered to make the hematocrit reach 28% or more. After protamine neutralizes heparin, 10 to 20 U of platelets should be transfused, preferably fresh blood. If necessary, 6 to 10 U of cold precipitation can be added. After treatment by the above methods, generally satisfactory hemostatic effect can be achieved.

5. Pay attention to brain protection

Reliable brain protection is also one of the key factors for successful surgery. Focus on the following issues:

(1) Determine the depth of cooling according to the length of the stop cycle. If the estimated stop cycle time is more than 60 to 80 minutes, the core temperature should be reduced to 15 to 18 ° C.

(2) When the temperature reaches the predetermined requirements, the flow should still be continued for 10 to 15 minutes to evenly cool the tissue.

(3) Full attention should be paid to the speed of cooling and re-warming to avoid the temperature difference between the blood temperature and the core temperature> 10 ° C.

(4) Methylprednisolone and thiopental sodium can be added during the cooling period to strengthen the brain protective effect.

(5) Blood glucose concentration should be monitored during cooling and rewarming to keep blood glucose 200mg / ml to avoid causing cerebral edema.

(6) In the case of retrograde inferior vena cava perfusion, the internal jugular vein pressure should be 25-30mmHg, and when selective cerebral perfusion is performed, the right radial arterial pressure should be 50-70mmHg. Excessive pressure can cause cerebral edema.

(7) The ice cap cools down on the head and neck during the stop cycle.

1. Strictly control blood pressure

It is required that the arterial systolic blood pressure be maintained at 100-120 mmHg within 24 hours after operation to prevent anastomotic bleeding, bleeding or tearing, and can reduce or reduce brain complications.

2. Strict observation and treatment of neurological complications

Brain complications after aortic arch tumors are the main cause of early postoperative death. The longer the off-cycle time, the higher the incidence of brain complications. The pupil size, reaction to light, changes in consciousness, and the presence of mental abnormalities should be strictly observed after surgery. At the same time, there should be signs of localization. Once intracranial hemorrhage and cerebral embolism are suspected, brain CT examination should be performed in time, and hormones should be applied at the same time. And dehydration and diuretics to prevent cerebral edema. Postoperative psychiatric disorders usually disappear completely after symptomatic medication.

3. Pay attention to protect kidney function

Some patients have mild renal insufficiency before surgery, and deep hypothermia circulatory arrest also has a significant effect on renal function. Within 3 days after surgery, renal function should be checked at least twice a day. Once renal function declines, a small dose of dopamine [2 ~ 3 g / (kg · min)] should be given in a continuous intravenous drip. If necessary, perform peritoneal dialysis or hemodialysis as soon as possible.

4. Prevention of infection

Because of the long time of operation and extracorporeal circulation and large wounds, postoperative infections or endocarditis are more likely to occur in patients after general cardiac surgery, so broad-spectrum antibiotics must be applied for at least 3 to 5 days.