Aortic coarctation is a rupture of the intima of the aortic wall causing blood to enter and travel along the aortic wall, eventually leading to separation of the intima from the middle layer of the aortic wall.
The true incidence of aortic coarctation is difficult to determine for 2 main reasons: 1 because aortic coarctation can be rapidly fatal and may be incorrectly attributed to other causes when patients die pre-hospital; 2 because it is easily missed at the first onset and because such early deaths are mostly attributed to other causes. The incidence of aortic coarctation in China is about 5-10 per 100,000 person-years, and it is estimated that about 50-100,000 people develop the disease each year in China.
The prognosis of aortic coarctation is extremely poor, with approximately 50% of patients dying within 48 hours of onset and approximately 90% dying within 1 month of onset.
Risk factors for aortic coarctation include a variety of conditions that cause degeneration of the middle aorta or create excessive pressure on the aortic wall. Two-thirds to three-fourths of patients have a history of uncontrolled hypertension. The genetic predisposition to predispose to aortic coarctation can lead to a range of genetic syndromes, such as Marfan syndrome, Roy-Dietz syndrome, and atypical familial genetic syndromes. Data from the International Registry of Acute Aortic Coarctation show that 50% of patients under 40 years of age have a family history of Marfan syndrome.
Although uncommon, aortic coarctation may also be painless, with older patients presenting more often with syncope, stroke, and congestive heart failure. Patients with hyperlipidemia and Marfan syndrome are more likely to have no painful manifestations.
Ischemia of tissues and organs due to the involvement of branch aortic vessels by the coarctation is considered to be a common clinical manifestation, which leads to the development of related complications. There are many mechanisms by which such complications occur. Most vascular obstruction is due to endothelial sheets blocking branch vessel openings or entering the vessel directly. Other causes include thrombus or embolus obstruction of a true or false lumen of a branch vessel, direct compression of a branch artery or adjacent tissue by a dilated false lumen, rupture of the false lumen leading to blood flow into adjacent structures, and involvement of the coronary artery or aortic valve by the entrapment can lead to heart failure.
Early in the onset of acute aortic coarctation, physical examination is insensitive to renal and intestinal ischemia. Elevated serum creatinine or intractable hypertension may be associated with renal ischemia but may also represent baseline values in patients with lack of prior data or untreated disease. Serum markers of intestinal ischemia do not manifest until several hours after onset.
The heart is the most commonly involved organ in aortic coarctation involving the ascending aorta. Unlike other visceral organs, the vast majority of circulatory complications are a direct result of clamping resulting in abnormal anatomic relationships.
Acute aortic regurgitation is the most common circulatory complication in Stanford type A aortic coarctation, with an incidence of 41% to 76%. Three mechanisms have been identified that lead to acute aortic valve insufficiency: 1 dilatation of the prosthetic lumen leading to dilatation of the aortic root ultimately affecting aortic valve closure, 2 tearing of the aortic coarctation to the root leading to disruption of aortic valve continuity ultimately leading to leaflet prolapse, and 3 tearing of the endothelial sheet during diastole blocking adequate leaflet closure. Clinical symptoms of aortic regurgitation due to entrapment vary in degree from a systolic murmur due to mild hemodynamic alterations to congestive heart failure and cardiogenic shock.
Myocardial ischemia or myocardial infarction is a rare but serious complication of acute aortic coarctation. Data show that ECG-confirmed myocardial ischemia accounts for approximately 19% of patients with acute aortic coarctation. Compression of the proximal coronary artery by a false lumen or obstruction of the coronary artery opening by an intimal lamina can affect the coronary artery supply.
Clinically, symptoms of myocardial ischemia associated with entrapment may be difficult to distinguish from the ECG of primary myocardial ischemia or infarction, which increases the likelihood of misdiagnosis and inappropriate treatment.
Heart failure is a relatively uncommon complication of aortic coarctation, with an incidence of approximately 6%. Heart failure may be caused by acute aortic closure insufficiency, acute myocardial ischemia or infarction, or pericardial tamponade. Data show that patients with aortic coarctation combined with heart failure often have atypical symptoms, which can easily lead to delayed diagnosis.
Pericardial effusion and pericardial tamponade are common complications of acute aortic coarctation, and the mechanisms of occurrence include 2 main types. The most common is infiltration of tissue fluid into the pericardial cavity through the weak vessel wall of the false lumen, resulting in a small amount of pericardial effusion, which accounts for approximately one-third of patients. Less commonly, the entrapment breaks directly into the pericardial cavity, resulting in rapid pericardial filling. Approximately 8 to 10% of patients with acute Stanford A aortic coarctation have combined pericardial tamponade, which often predicts a poor clinical prognosis and should be operated on immediately upon detection of pericardial tamponade.
Syncope is an easily diagnosed complication associated with clamping, with an incidence of approximately 13%.
The main causes of syncope include.
1, cardiogenic (e.g., severe aortic regurgitation, ejection obstruction, pericardial tamponade).
2, vascular origin (e.g., inadequate cerebral blood supply and active aortic arch pressure receptors).
3, neurogenic (e.g. painful stimulation of the vagus nerve).
4, low volume (pseudocavity breaking into the chest cavity), etc. Regardless of the cause, syncope increases the risk of recent adverse events in aortic coarctation.
Acute aortic coarctation has a high incidence of neurological complications, with a 17% incidence of neurological complications. Neurologic complications may result from hypertension, cerebral ischemia, cerebral thrombosis, or neurologic compression.
Although uncommon, acute paraplegia due to spinal cord ischemia caused by aortic coarctation is often described as the first clinical manifestation, with an incidence between 1% and 3%.
Clinically, it has been found that 50% of the neurological complications associated with entrapment present as transient and one third of patients have no complaints of chest pain, which makes accurate diagnosis and treatment difficult.
Pleural effusion is the most common pulmonary complication of acute aortic coarctation, accounting for approximately 16% of patients. A large amount of pleural effusion may be the flow of blood from the ruptured aorta into the pleural cavity, and a small amount may be inflammatory exudate rather than ruptured bleeding.
Other pulmonary complications include pulmonary artery compression due to entrapment and main pulmonary artery fistula, both of which can present as significant dyspnea. Approximately 3% of patients present with hemoptysis associated with aortic coarctation, which may be due to either compression of lung tissue by a false lumen or rupture of the coarcted aneurysm into lung tissue, ultimately leading to massive hemoptysis or even death of the patient.
Intestinal ischemia is the most common gastrointestinal complication of acute aortic coarctation this may be caused by ischemia or low blood pressure. It is the most common cause of death in patients with Stanford B aortic coarctation. Intestinal ischemia is most often manifested as eh abdominal pain, but the pain may be atypical combined with the absence of an abdominal physical examination, so the entrapment is not detected early. Unfortunately, once a positive serum marker of intestinal ischemia or necrosis is detected, it is often too late to save the patient’s intestine. It is therefore important to clarify the presence or absence of intestinal ischemia in patients with acute aortic coarctation who present with abdominal pain.
Gastrointestinal bleeding is a rare but potentially catastrophic complication of acute aortic coarctation. Gastrointestinal bleeding associated with clamping may result in limited bleeding due to intestinal necrosis or major bleeding due to arteriosophageal fistula or pseudo-lumenal rupture into the small intestine. Although rare, entrapment-associated gastrointestinal bleeding should be a priority in all patients with combined bleeding and chest and abdominal pain from entrapment.
Anatomically, acute aortic coarctation can be staged based on the location of the primary rupture or simply on whether the coarctation involves the ascending aorta regardless of the location of the rupture. Accurate staging is important because it can determine whether to treat surgically or conservatively. The two most common types of staging used clinically are the DeBakey staging and the Stanford staging. For staging purposes, the ascending aorta here includes the proximal aorta to the innominate artery, and the descending aorta includes the left subclavian artery and the aorta distal to it.