Although aortic coarctation is relatively rare, the mortality rate is high. In recent years, due to the improvement of medical workers’ awareness of this disease and the advancement of diagnosis and treatment techniques, the diagnosis rate of this disease has increased significantly and the mortality rate has decreased significantly.
(I) Pathology and pathophysiology
The pathological basis for the formation of aortic coarctation is the weakness of the middle layer of the aorta, which manifests as cystic necrosis of the middle layer, rupture of elastic fibers and smooth muscle, and formation of fibrosis and vitreous degeneration. It is most commonly seen in elderly and young to middle-aged patients with Marfan syndrome. Due to the enlargement of the lumen of the arterial middle layer lesion, the adhesion of the intima to the middle layer decreases, resulting in tearing of the intima under the action of internal and external forces, and blood flows between the intima and the middle layer, causing it to peel off and progress toward the circumferential and long diameters, forming an aortic entrapment.
The dissection of the interlayer toward the proximal end can affect aortic valve function and coronary blood flow. Prolapse of the valve leaflets causes incomplete closure due to involvement of the aortic annulus (mostly coronary valve or right and no junction) or compression of the annulus by an intercalated thrombus. Proximal detachment of the intima may tear the coronary artery from the root or detachment of the intima downward to block coronary blood flow, resulting in acute myocardial infarction or sudden death. Distal detachment of the intima may cause disruption of blood supply to the cephalobrachial artery, intercostal artery, celiac artery, superior mesenteric artery, and renal artery.
Malfunction of the corresponding organs may occur. Such as hemiplegia, coma, paraplegia, and even life-threatening. In individual cases, the peeled intima blocked the iliac artery or femoral artery, resulting in impaired blood supply to the lower extremities and ischemic necrosis of the lower extremities. If the endothelium is weak at a certain place, blood will penetrate into the true lumen and form a secondary rupture, causing the pressure in the false lumen to drop and the peeling to stop temporarily.
If the pressure in the false lumen rises for various reasons, peeling continues, and sometimes multiple ruptures are found distally. If the distal endothelial rupture is small and the pseudoluminal pressure is too high, the weak parts of the middle and outer membranes may be penetrated outward, resulting in hemorrhage, pericardial tamponade, intra-thoracic or intra-abdominal hemorrhage or mediastinal retroperitoneal hematoma leading to death.
Aortic entrapment typing.
Type I: The entrapment involves the entire aorta, with the primary rupture in the ascending aorta and the endothelium peeling off along the long diameter of the aorta. It often involves the coronary artery, aortic valve, cephalobrachial artery, intercostal artery, abdominal cavity artery, superior mesenteric artery and renal artery, and sometimes strips one iliac or femoral artery into a false lumen resulting in impaired blood supply to the lower extremities.
Type II: The entrapment involves the aorta in the ascending arch and does not extend distally beyond the left subclavian artery.
Type III: Type IIIA if the entrapment involves only the thoracic descending aorta. Type IIIB: Type IIIB is when the thoracic descending aorta and the entire abdominal aorta are involved.
Most patients die in the acute phase.
(II) Clinical manifestations and diagnosis
About 90% of patients have sudden onset of severe pain in the anterior chest, back or/and abdomen, which is stabbing, tearing or slashing and unbearable. The patient is irritable and sweating profusely. The pain may be transmitted in the direction of the arterial pathway. Angina pectoris and myocardial infarction may occur if the coronary artery is involved, cerebral insufficiency and even coma if the cephalobrachial artery is involved, paraplegia if the intercostal artery is involved, and symptoms of insufficient blood supply to the abdominal organs in individual cases. Acute aortic valve insufficiency can lead to acute left heart failure. Physical examination: painful appearance, shock in severe cases, indifference, cold and pale extremities, little or no urine, but blood pressure can be mostly in the normal range. The arteries of the extremities may have asymmetrical pulsation of the bilateral carotid arteries, and the blood pressure may vary. Patients in the chronic phase mostly have vague pain in the chest, back and abdomen. The history of the disease mostly has the course of acute attack symptoms.
(C) Treatment
Acute aortic coarctation should be treated with a comprehensive treatment based on surgery, that is, surgical operation should be performed as soon as possible while active drug treatment.
Surgical treatment.
1.Type I and II aortic coarctation
(1) Basic method.
General anesthesia and hypothermic extracorporeal circulation, insertion of perfusion tube in right subclavian artery, insertion of second-step venous drainage tube in right atrium, insertion of left heart drainage tube in right upper pulmonary vein or main pulmonary artery suction. If the arch requires simultaneous surgery, separate perfusion of the head combined with systemic stop circulation is used.
(2) Surgical method.
Median split sternotomy, extracorporeal circulation with intubation of the above-mentioned parts, direct perfusion of the coronary artery with stopping fluid, and cooling of the heart surface with ice water and ice chips. The ascending aorta was blocked at a nasopharyngeal temperature of about 25°C, and the aorta was incised for coronary artery perfusion. Probe for coronary artery and aortic valve involvement.
Depending on the situation, there are 3 methods of proximal management as follows.
①If the coronary artery opening is not involved in endothelial dissection and there is no aortic valve insufficiency, the ascending aorta should be cut off above the coronary artery opening, and an artificial vessel of corresponding caliber should be taken for transplantation; if there is aortic valve insufficiency caused by non-clamping in combination, the aortic valve should be replaced first.
If the endothelial detachment involves the coronary artery opening up to the aortic valve annulus and causes mild or moderate aortic valve incompetence, root replacement surgery with aortic valve preservation is feasible, first freeing the left and right coronary artery openings like a button, removing the ascending aorta up to the aortic valve annulus, and if there is prolapse of the aortic valve junction, it can be suspended and sutured first.
If the endothelial stripping involves the coronary artery opening and aortic annulus, and there is unrepairable aortic valve insufficiency, aortic root replacement with artificial components is performed in the same way as aortic root aneurysm combined with aortic valve insufficiency. After the proximal end is treated, when the nasopharyngeal temperature is reduced to 20°C, the unnamed artery and the left common carotid artery are blocked, 10 ml/kg/min head is perfused alone, and the extracorporeal circulation is stopped systemically, the aortic blocking clamp is removed, and the distal end is explored.
The following treatments are available depending on the situation.
①If the entrapment does not involve the aortic arch, the ascending aorta is cut off at the distal aneurysm neck, and the end of the line is anastomosed with the artificial vessel by 4-0 or 3-OProlene continuous suture;
(ii) If the intercalation involves the arch and its distal part, the false lumen is small and there is no secondary rupture in the ascending arch, the aorta is cut at the proximal end of the opening of the unnamed artery, and the false lumen is closed with a continuous suture of the inner membrane and outer membrane with a spacer, and then the end-to-end anastomosis is made with the artificial vessel;
(3) If the clamping involves only the ascending arch, half or full arch replacement is performed, and the method is the same as that for arch aneurysm;
④In recent years, the authors have used total arch replacement + “stenting elephant trunk technique” to treat type I aortic coarctation and achieved good results. This procedure is suitable for cases in which the intimal rupture is far from the arch, the cephalobrachial artery has a coarctation, or the descending aorta is dilated.
The aortic arch is cut between the left common carotid artery and the left subclavian artery, the left subclavian artery is cut at the root, the proximal end of the left subclavian artery is closed with continuous sutures, the 26-30 mm supporting artificial vessel is inserted into the true lumen of the descending aorta, the distal end of the 4-branch artificial vessel is anastomosed to the thoracic descending aorta, and the perfusion of the thoracic descending aorta is restored through the perfusion branch, and then the left subclavian artery, the left common carotid artery, the unnamed The anastomosis of the distal end of the left subclavian artery, the left common carotid artery, and the sine qua non artery to the artificial vessel with branches was then completed sequentially. After venting, the blocking clamp of the cephalobrachial artery was opened, the proximal artificial vessel was blocked, extracorporeal circulation was restored and rewarmed, and the proximal ends of the four artificial vessels with branches were anastomosed with the ascending aorta. After venting again, the blocking clamp was opened, cardioversion was performed, and the operation was completed.
2.Type III aortic coarctation
The surgical effect of this type of clamping is worse than that of type I and II, and the effect of conservative medical treatment is similar to that of surgical operation, but the following conditions should be treated surgically: pain and hypertension cannot be controlled by medication; the aneurysm expands more significantly in a short period of time; there are symptoms of compression; there is impaired blood supply to important organs; and there is blood accumulation in the left thoracic cavity.
For those who are not involved in the distal part of the aortic arch, if the expansion is limited to the proximal part of the descending aorta, partial thoracic descending aorta resection with artificial vessel replacement is feasible. A simple block plus “femoral artery cannulation arterial transfusion method” is used. Before blocking the artery, heparin 3mg/kg is injected intravenously, and an arterial perfusion tube is inserted into the left femoral artery to aspirate the bleeding from the operation field into a blood reservoir for backup.
Methods and clinical significance of additional staging.
I. According to DeBakey.
I and II aortic coarctation root lesions differ in degree, we divided them into three types (see Figure 1).
Type a: normal sinus type: the entrapment does not involve the sinotubular junction and its proximal end, the aortic sinus part is normal, and there is no aortic valve closure insufficiency. The aortic sinus portion does not require surgical management.
Type b: mild root involvement type: the aortic sinus section is less than 3.5 cm in diameter and the entrapment involves the right coronary artery resulting in partial or complete detachment of the intima at its opening; there is one or two aortic valve junction avulsions resulting in mild to moderate aortic valve closure insufficiency. Aortic sinus plication, aortic valvuloplasty, right coronary artery bypass grafting, or DAVID surgery is required.
Type C: Severe root involvement type: Significant sinus dilatation of 5 cm or more; or sinus diameter between 3.5 and 5 cm but disruption of the sinotubular junction structure; with severe aortic valve insufficiency. Bentall’s surgery with a prosthetic vessel with a valve is required.
II. Clinical significance of the staging.
Determine the timing of surgery: in principle, both type I and type II coarctation should be actively treated with surgery. Most type a patients are slow and do not need emergency surgery; type b and C patients often need emergency surgery because of the following factors: pericardial blood accumulation causing cardiac compression leading to low heart row, acute myocardial blood supply disorder due to coronary artery involvement, acute left heart failure due to severe aortic valve closure insufficiency.
Definitive surgical approach.
Type a: only the ascending aorta and its distal artificial vessel replacement is done, and the proximal anastomosis is located above the coronary artery opening, there are 60 cases in this group.
Type b: The procedure should be performed with root formation as the best choice, such as root replacement with preservation of the aortic valve and right and left coronary artery reimplantation (David’s procedure), and there were 7 cases in this group; or its modified procedure: such as replacing one or two of the sinuses (mostly right and non-coronary sinuses) plus coronary artery opening graft or using saphenous vein right coronary artery trunk bypass graft.
Type C: Severe structural destruction of the aortic root, requiring aortic root replacement with a valved prosthetic vessel.
Initial determination of prognosis.
Type a: simple surgical approach, easy operation, low perioperative risk; proximal lesion is completely removed, no postoperative pseudoaneurysm; no need for anticoagulation; good long-term results.
Type b: difficult to operate, difficult to judge, complicated technical operation, and higher surgical risk. Because of the preservation of its own aortic valve, postoperative anticoagulation therapy is not required, and patients have a higher quality of survival. However, there is a risk of aortic valve closure insufficiency aggravated by the need for valve replacement (one case in this group has been replaced, and two other cases are under observation).
Type C: the surgical technique is less difficult, the intraoperative risk is not high, because the aortic valve is replaced, long-term postoperative anticoagulation therapy is required, and the quality of survival is relatively poor; individual patients die of heart failure due to progressive enlargement of the left ventricle.