Post-Coarctectomy Syndrome - Causes, Symptoms, Diagnosis and Treatment

What Is Post-Coarctectomy Syndrome?

Post-coarctectomy syndrome is a gastrointestinal symptom that usually occurs with paradoxical hypertension after a coarctectomy. The symptoms usually appear around the third day and are characterized by abdominal pain, vomiting, fever, etc.

Early return to feeding after coarctectomy, which changes the mesenteric arteries (blood vessels that supply the midgut), is thought to be the cause of post-coarctectomy syndrome. Delayed feeding and good control of blood pressure during the postoperative period have been shown to reduce and prevent the condition.

What Is a Coarctectomy?

It is a surgical procedure to correct the congenital (present at birth) narrowing (coarctation) in a small section of the aorta. The aorta is the main blood vessel in the body that carries blood away from the heart to the rest of the body. The narrowing makes it hard for the blood to pass through the aorta leading to congestive heart failure.

Coarctation of the aorta is often associated with other congenital heart defects (like aortic stenosis and ventricular septal defects) and genetic conditions (like Turner syndrome). This predisposes the individual to life-threatening complications, which can be managed only through surgical intervention.

The preferred surgical approach in these individuals is a combination of coarctectomy and interdigitating arch anastomosis. The procedure involves the following steps:

1. Resection of the aorta at the level of coarctation.

2. Resection of the ductal tissue causing the narrowing.

3. An incision is made in the anterolateral aspect of the thoracic aorta (descending part of the aorta that runs through the chest).

4. The supra-aortic trunks (ascending branches of the aorta that supply the head and the upper extremities) are mobilized.

5. And finally, direct end-to-end anastomosis is done between the greater curvature native aortic arch and the descending aorta.

Regardless of the procedure's success, coarctectomy is always accompanied by respiratory, cardiovascular, gastrointestinal, and renal complications. Post-coarctectomy syndrome is one of the gastrointestinal complications of coarctectomy.

What Causes Post-Coarctectomy Syndrome?

Several theories have been put forward to explain the condition, and the most accepted theories suggest the syndrome to be caused either due to mesenteric arteritis or by the renin-angiotensin system activation.

1. Mesenteric Arteritis: It is defined as the inflammation of the mesenteric arteries that supply the midgut. This theory presumes that prior to coarctectomy, the mesenteric arteries are subjected to subnormal pressure because of coarctation, which then gets reversed after the procedure. The newly increased pulse pressure and a more pulsatile blood flow lead to increased intra-arterial wall tension in the mesenteric vessels. This increased tension, when combined with the fragility of the vessels (due to the lack of surrounding supporting structures), will result in intimal damage, thrombosis, and secondary necrotizing arteritis, all of which combine to form post-coarctectomy syndrome.

2. Activation of Renin-Angiotensin-Aldosterone System (RAAS): According to this, coarctectomy stimulates the sympathetic nerve fibers in the aortic isthmus, which initiates the spinal reflex to release renin. The renin then shunts the blood from the mesenteric arteries, thus causing abdominal symptoms seen in post-coarctectomy syndrome.

What Are the Symptoms of Post-Coarctectomy Syndrome?

Some of the commonly seen symptoms are:

1. Abdominal pain and tenderness.

2. Ileus refers to the intolerance of oral intake due to inhibition of gastrointestinal propulsion without signs of mechanical obstruction.

3. Vomiting.

4. Fever.

5. Melena refers to black stools that occur as a result of gastrointestinal bleeding.

6. Leukocytosis (a term used to describe elevated white blood cell count).

7. Paradoxical hypertension is the first and the most commonly seen complication of coarctectomy. In patients suffering from coarctation, the left ventricle works hard to pump blood through the narrowed aorta; as a result, blood pressure rises in the left ventricle leading to hypertension.

Surgical correction (coarctectomy) of the coarctation is supposed to bring the blood pressure to normal levels; on the contrary, many of these patients experience paradoxical hypertension, which is more severe than preoperative hypertension. It is believed that the same two mechanisms- stimulation of sympathetic nerves between the aortic isthmus and activation of RAAS also caused paradoxical hypertension. In fact, paradoxical hypertension is the immediate response to coarctectomy, followed by the abdominal symptoms seen in post-coarctectomy syndrome.

If left untreated, the abdominal symptoms will progress to mesenteric ischemia and infarction. This will lead to a necrotizing and gangrenous bowel; this is often fatal and should be treated immediately.

How Is Post-Coarctectomy Diagnosed?

Individuals suffering from post-coarctectomy syndrome will develop symptoms within a week while receiving postoperative care for coarctectomy. This is helpful for the initial diagnosis. However, it is necessary to perform a physical examination, laboratory investigations, and imaging studies before reaching a final diagnosis.

1. Physical Examination: A physical examination will reveal elevated blood pressure (between 140/80 mm/Hg to 180/100 mm/Hg), indicative of paradoxical hypertension.

2. Laboratory Tests: Laboratory work-up should include a basic metabolic panel, a complete blood count (to check for white blood cell count and neutrophil count), a liver function test, and a urinalysis. These will help to determine the lactate dehydrogenase level, cardiac troponin Ⅰ level, creatinine kinase MB level, amylase level, and lipase level.

3. Computerized Tomography (CT) Test: CT of the abdomen is the imaging choice for suspecting mesenteric ischemia.

4. Magnetic Resonance Imaging (MRI): MRI scan is a good alternative for patients who cannot undergo CT.

5. Mesenteric Angiography: It is a test to look at the blood vessels of the small and large intestines and can be used to diagnose and treat mesenteric arteritis.

How Is Post-Coarctectomy Treated?

Addressing paradoxical hypertension with the help of aggressive antihypertensive medication has been known to prevent or reduce the symptoms seen in post-coarctectomy syndrome. In addition, it is believed that the antihypertensive medication aids in reducing the mechanical stresses in the mesenteric arterial walls generated by increased pulsatile blood flow and decreasing the vasoconstrictive and blood shunting effects of the RAAS.

Some commonly used antihypertensive medications are beta-blockers, arterial smooth muscle relaxants, and angiotensin-converting enzyme (ACE) inhibitors. In most cases, the abdominal symptoms will subside after this; however, if the symptoms persist, conservative management with the help of drugs (like glucocorticosteroids and immunosuppressive drugs) and surgery will treat the symptoms.

Conclusion:

Post-coarctectomy syndrome comprises abdominal symptoms seen after coarctectomy. These symptoms have become rare with the advent of nonsurgical intervention to treat coarctation. However, if the condition does affect the individual, prompt diagnosis and treatment are advised to prevent life-threatening conditions. It can also be prevented by an early (around eight years to nine years) coarctectomy.