Coarctation of the aorta (narrowing of the isthmus of the main artery) accounts for about 6-8% of all congenital defects of the heart and large vessels. It consists in narrowing a section of the aorta within its arch. It is three times more common in boys. May be associated with Turner syndrome - X chromosome monosomy in girls. What exactly is it about? How is it manifested? Can it be cured effectively?

Main artery stenosis , i.e.aortic coarctation , in the vast majority of cases is located within the so-called aortic isthmus. The aortic isthmus is called a small physiological stricture just below the left subclavian artery exit. Its abnormal development is caused by disorders at the stage of embryogenesis. The degree of stenosis can vary from slight to almost complete obstruction of the aorta. Coarctation can have different morphology - it can occur in a short or long section of the main artery. From a clinical point of view, important is the division based on the topographic relation of the stenosis to the ductus arteriosus (Botalla) - the structure ensuring the connection between the pulmonary trunk and the initial segment of the descending aorta, characteristic of the fetal circulation. There are 3 types:

  • superconductive (formerly infantile) - narrowing above the arterial duct
  • perineural - stenosis at the height of the arterial duct
  • sub-wired (formerly adult type) - narrowing below the cable

Aortic coarctation may be an isolated defect or coexist with other abnormalities. The most common accompanying disadvantages include:

  • bicuspid aortic valve
  • ventricular septal defect
  • aortic arch hypoplasia
  • atrial septal defect

The combined presence of aortic coarctation, subvalvular aortic stenosis, and mitral stenosis is called Shone's syndrome. Aortic stenosis associated with other defects is much more common in infants.

What are the symptoms of aortic stenosis?

The dynamics of the course of the defect and its symptoms depend on several factors: the degree of narrowing and its location in relation to the ductus arteriosus, the rate of duct closure and coexisting defects.

In case of critical stenosis, symptomsSevere, refractory heart failure (dyspnoea, tachycardia, hepatomegaly, feeding difficulties, low weight gain) appear in the neonatal period. The condition of such a child is serious and requires urgent intervention. The other symptoms that come to the fore are due to impaired blood supply to the lower body:

  • weakness or lack of pulse in the lower limbs
  • symptoms of renal failure - decrease in urine volume, anuria; are the result of impaired renal blood flow
  • necrotizing enterocolitis - intestinal ischemia may lead to intestinal necrosis, further disruption of the intestinal barrier and, consequently, sepsis
  • metabolic acidosis

In general, if left untreated, critical coarctation (very often associated with another defect) can lead to severe multiorgan failure due to visceral ischemia. Such infants, as a rule, do not live until the age of 6 months.

If the stenosis is supra-ductal, the lower body receives blood from the right ventricle through the patent ductus arteriosus. This means that symptoms may not appear immediately after birth (the pulse in the legs may be well felt), and the symptoms of heart failure and lower body ischemia appear as the duct gradually closes. Blood from the right ventricle is non-oxygenated, so the consequence of a right-left leak through the bubonic tube is cyanosis of the lower body in this case.

Coarctation of a lesser intensity (usually it is an isolated defect) may be asymptomatic for many years. Symptoms may appear in older children or adults. Often the first manifestation of a long-unknown defect are its complications, e.g. a stroke. It happens that it is detected accidentally. Symptoms that may appear are mainly due to high blood pressure in the upper body (above the stenosis):

  • headaches
  • nose bleeds
  • hypertension (measured on the upper limbs) - may be the only symptom
  • feeling of "throbbing around the neck"
  • intermittent claudication - pain in the lower legs that occurs while walking or running, but resolves when you stop moving; is the result of ischemia in the lower limbs

Sometimes there is a noticeable disproportion in the figure, in which the upper body is better built - wider shoulders, chest and larger arms as well as slim lower limbs.

In such cases of aortic stenosis, the so-called circulationcollateral. Adaptation mechanisms increase the flow through other vessels, increasing the efficiency of blood circulation in the lower parts of the body. The internal and intercostal arteries are mainly involved in the formation of collateral circulation. Its development can eliminate the difference in heart rate between the upper and lower limbs. Sometimes the collateral vessels can cause the formation of "usuras" - bone defects visible on the X-ray image by pressing the lower edges of the ribs.

How to treat coarctation?

In the case of critical stenosis detected in newborns, it is advisable to perform emergency surgery after stabilization of the clinical condition. Previously, a prostaglandin (PGE1) preparation was routinely administered by intravenous infusion. The goal of this is to keep the ductus arteriosus, which is the main source of blood supply to the lower body, as long as possible.

If coarctation is diagnosed in old age, cardiac surgery is performed as scheduled. However, the operation should not be delayed due to the possibility of long-term complications of the defect. One of the main indications for the procedure is the presence of arterial hypertension.

The basic technique used in aortic coarctation is the so-called Crafoord surgery consisting in excision of the narrowed section and end-to-end anastomosis of the aorta. When the stricture is diffuse, that is, longitudinally, it may not be possible to sew the ends together. In such cases, the defect in the main artery can be replaced with a plastic vascular prosthesis. Sometimes a complete aortic dissection is not necessary. Then, the plasty of the stenosis is performed with the use of a special patch prepared from the own subclavian artery. Balloon angioplasty is also used in the treatment of coarctation. This procedure consists in widening the narrowing site with the use of a balloon catheter inserted through the access from the femoral artery. It can also be related to the implantation of the so-called stent. Angioplasty is most often performed in the event of recurrence of the isthmus stenosis, i.e. recoarctation after surgery performed in early life. Endovascular treatment is also an alternative for older children who are later diagnosed with the defect.

What are the postoperative complications?

The earliest postoperative complications include bleeding from the site of anastomosis or collateral vessels. Later, after successful treatment, high blood pressure that is difficult to control may still persist. The rarest but most dangerous complication of treatmentoperative is damage to the spinal cord followed by paraplegia - binomial palsy. It is the result of a critical limitation of the flow through the anterior spinal artery (Adamkiewicz's artery) and ischemia of the spinal cord. Postoperative mortality in elective surgery patients is negligible. Higher rates are recorded among the youngest patients with a severe, complex defect undergoing surgery for vital indications. Here, the mortality rate ranges from a few to a dozen or so percent.

What is the prognosis for patients with coarctation?

Problems and treatment of coarctation patients do not always end with successful surgery. The defect tends to recur. Restenosis is called restenosis. A very significant problem is arterial hypertension, which may persist even after a fully effective corrective procedure. Long-term hypertension results in other long-term complications of coarctation, which may prove fatal. These include:

  • left ventricular hypertrophy - in response to increased stress on the heart
  • development of atherosclerosis - as a result of damage to the vascular endothelium
  • heart attack
  • stroke
  • aneurysms of the cerebral vessels - can rupture and be a source of dangerous intracranial hemorrhages
  • aortic aneurysms
  • aortic wall dissection

Based on autopsy studies, it is estimated that as many as 90% of untreated aortic coarctation cases are fatal before the age of 50, and the average survival time is 35 years. Nowadays, thanks to more and more developed diagnostic methods, the defect can be diagnosed more effectively at an earlier age. The treatment itself is also improved. This makes the survival time of patients suffering from aortic stenosis longer.

Sources:

1. Hoffman M., Rydlewska-Sadowska W., Rużyłło W., Wady heart, Warsaw, Wyd. PZWL, 19802. Kawalec W. Turska-Kmieć A., Ziółkowska L., Congenital heart defects, [in:] Kawalec W. (ed.), Ziółowska H. (ed.), Grenda R. (ed.), Pediatria , vol. 1, Warsaw, PZWL, 20163. Skalski J.H., Haponiuk I., Aortic stenosis, [in:] "Children's cardiac surgery" Scientific Publishing House "Śląsk", Katowice 2003, edited by prof. Janusz H. Skalski and prof. Zbigniew Religa (online)

Category:

Cardiology