Aortic isthmic stenosis is a congenital heart defect. It involves a narrowing of the aorta.
What is aortic isthmic stenosis?
Aortic isthmic stenosis (coarctatio aortae) is the second most common type of congenital heart defect. In this case, a luminal narrowing of the aorta (main artery) occurs in the region of the aortic isthmus (isthmus aortae). This stenosis results in an increase in pressure on the outflow tract of the left ventricle. The narrowed aorta increases resistance. To overcome this, the heart works harder, causing it to enlarge and thicken, which results in further weakening. Stenosis of the aortic isthmus is congenital and is seen in 7 percent of all heart defects. The malformation is more common in boys than in girls.
Causes
What causes aortic isthmus stenosis is not known exactly. There are two theories for its development. The first theory considers a decrease in blood flow in the aorta, which occurs during the embryonic period, to be the trigger. The second theory blames scattered tissue of the ductus arteriosus for the narrowing. Physicians divide aortic isthmic stenosis into two distinct forms:
- Preductal aortic isthmic stenosis.
- The postductal aortic isthmus stenosis
In the case of preductal aortic isthmic stenosis, the narrowing exists anterior to the junction of the ductus arteriosus. In addition, there is often tubular underdevelopment of the aortic arch and parts of the descending aorta. Not infrequently, there is also a ventricular septal defect. In most affected individuals, the severe degree of aortic isthmic stenosis prevents blood flow from the ascending to the descending aorta. For this reason, blood supply to the ascending aorta occurs almost exclusively through the pulmonary artery. In the process, venous blood flows through the open ductus arteriosus. As a result, there is a reduction in blood flow to the lower part of the body. However, if the ductus is closed, the femoral pulses weaken, which in turn causes the blood pressure to drop. This results in an increased risk of anuria and renal failure. In the postductal form, which is less common, the stenosis of the aortic isthmus is located posterior to the confluence of the duct and toward the aorta. The narrowing of the lumen bears resemblance to an hourglass.
Symptoms, complaints, and signs
The type of symptoms and the timing of their onset depend on the location of the aortic isthmic stenosis as well as its severity. In preductal aortic isthmic stenosis, there is a lack of oxygen as well as heart failure even in newborn infants. This is manifested by poor drinking, failure to thrive and cyanosis, in which the skin and mucous membranes turn bluish. Hegatosplenomegaly may also occur, in which the spleen and liver enlarge at the same time. This is a mixture of hepatomegaly and splenomegaly. If obstruction of the ductus botalli occurs, there is even a danger to life. Without timely treatment, the mortality rate of affected children is 90 percent. Postductal aortic coarctation is more difficult to diagnose because only a heart murmur and a difference in pulse are noticeable during screening examinations. Young children are often affected by nosebleeds, calf pain on exertion, cold feet and headaches. Adolescents, on the other hand, are at risk for window shoppers’ disease.
Diagnosis and progression
A physician can usually diagnose aortic stenosis by listening for a heart murmur. This occurs along with a difference in blood pressure between the upper and lower limbs. While there is high pressure in the arms, the pulse and blood pressure in the legs are rather weak. Further examination measures may include an echocardiogram (ECG), X-ray examination, angiography or magnetic resonance imaging (MRI). Precise examination results are possible with the help of a cardiac catheterization. In this procedure, doctors advance a tube, to which a measuring device or camera is attached, all the way to the heart. In this way, they assess the structure of the aorta, the blood pressure conditions and the blood flow. If the aortic coarctation is successfully eliminated, the affected children can usually bear weight completely again and are considered cured.However, they must undergo check-ups with a cardiologist for the rest of their lives. Potential long-term complications include bulges in the aortic wall.
Complications
Complications that may occur in association with untreated aortic isthmic stenosis (ISTA) depend on the exact location of the congenital stenosis and the type and severity of the narrowing. If the stenosis is still located anterior to the ductus botalli, the potential complications are particularly severe because the body cannot form alternate blood pathways (collaterals). Serious complications then arise even in newborns due to inadequate oxygen and nutrient supply to the lower half of the body and to internal organs such as the kidneys, liver and intestines. Severe neonatal jaundice may develop as a visible complication. Shock symptoms with hyperacidity of the blood may develop as a further complication. The pH may drop to below seven, usually resulting in irreversible brain damage. In less severe cases of ISTA, there are few complications in newborns because a network of collaterals has formed to provide much of the blood supply. In many cases, the disease then initially goes unnoticed and only becomes apparent in childhood or adulthood. If ISTA goes unnoticed and thus untreated, permanent high blood pressure can develop because the aorta’s Windkessel function is severely reduced. In these cases, the body attempts to compensate for the impending drop in diastolic pressure by increasing systolic pressure. The variety of complications that can result are similar to those of arterial hypertension.
When should you see a doctor?
Contributing to the symptoms of aortic isthmic stenosis (ISTA) that occur is the exact location of the narrowing of the main artery (aorta). It may be immediately anterior or posterior to the ductus arteriosus, which short-circuits the pulmonary circulation to the systemic circulation before birth. If the stenosis is located anterior to the shorting window (preductal), the left heart is severely stressed and also overloaded. Usually, the symptomatology is so severe that even the newborn must be treated surgically, as it is a life-threatening condition. If the narrowing of the aorta is located immediately behind the confluence of the ductus arteriosus (postductal), evasive vessels (collaterals) can usually form via various thoracic arteries. In many cases, therefore, postductal ISTA goes unnoticed until adulthood. The decision of whether to seek medical attention only arises when the condition is diagnosed incidentally. If aortic isthmic stenosis is not discovered and diagnosed until adolescence or early adulthood, further action should depend on how well the collateral circulation can compensate for the narrowing in the aorta. A measure of the “quality” of compensation is indirectly provided by the systolic pressure differences between the upper and lower body, for example between the brachial and leg arteries. The smaller the pressure differences, the better the collaterals function. Recommended for long-term prognosis is a review of the collaterals for size and course by an angiologist or cardiologist.
Treatment and therapy
In both preductal and postductal aortic isthmic stenosis, medical treatment is needed as early as infancy. Without appropriate therapy, the mortality rate is 60 to 90 percent. If serious symptoms occur, it is considered a medical emergency requiring immediate surgery. Because the heart does not have to be opened surgically, a heart-lung machine can usually be dispensed with. During the procedure, the surgeon makes an incision on the left side of the chest between two ribs. Clamping of the aorta is performed in front of and behind the stenosis during the surgical period. If it is a short-stretch stenosis, the diseased blood vessel area can be removed. The surgeon then sutures the ends of the vessels together. If, on the other hand, there is a longer-stretch stenosis, the lower section of the blood vessel can be sutured to the aortic arch. Parts of the left brachial artery are sometimes used for reconstruction.As an alternative to surgery, balloon dilatation can be performed to treat aortic coarctation. The narrowing is widened with the help of a balloon catheter. However, there is a risk of reoccurrence of narrowing afterwards. For this reason, surgery is usually preferred. If re-stenting occurs after surgery, balloon dilatation is considered more appropriate.
Outlook and prognosis
Aortic isthmic stenosis does not necessarily lead to decreased life expectancy or other symptoms in every case. However, those affected depend on therapy to relieve symptoms and prevent further complications. As a rule, the children must be supplied with oxygen immediately after birth, otherwise the newborns would die. Children can suffer from a developmental disorder in this process. Unfortunately, the limitation of this disorder is not possible in every case. In severe cases, the patient’s skin may turn blue. If left untreated, the disease can also lead to an enlargement of the liver or spleen, so that patients suffer from severe pain in these regions. Furthermore, aortic coarctation can lead to nosebleeds and severe headaches in everyday life. If the condition is not treated, it can significantly limit the patient’s life expectancy. However, the symptoms can be very well alleviated by treatment, so that the affected person can participate in everyday life without restrictions. As a rule, only a few further examinations are necessary after successful treatment.
Prevention
Aortic isthmic stenosis is a congenital condition. Therefore, there are no effective preventive measures.
Follow-up
Because aortic isthmic stenosis is a congenital disease, it cannot be treated causally, only symptomatically. A complete cure cannot be achieved in this case, and the options for follow-up care in aortic isthmic stenosis are also relatively limited. The patient is dependent on medical treatment, as otherwise premature death of the affected person may occur. If the acute symptoms of aortic isthmic stenosis occur, an emergency physician must usually be called directly or the hospital must be visited. The earlier the aortic isthmus stenosis is diagnosed and treated, the higher the probability of a positive course of the disease. After the operation, the patient must take care of his body and rest himself. They should refrain from strenuous activities or sports. Stress should also be avoided. The intake of nicotine and alcohol should also be kept to a minimum. In general, a healthy lifestyle with a healthy diet has a positive effect on the course of the disease. If the doctor prescribes medication for the patient with aortic coarctation, care must be taken to ensure that this medication is taken regularly. Likewise, interactions with other medications must be considered.
Here’s what you can do yourself
Priority in the treatment of aortic isthmic stenosis is consistently performed prophylactic and therapeutic measures. Thanks to diagnostic advances, we now know the effectiveness of careful cardiac monitoring and care. Care should be provided at a center experienced in the management of congenital heart defects. Elevated blood pressure often accompanies the disease. In addition to drug therapy, all blood pressure-lowering aids are welcome – if they do not place too great a burden on the patient. Two aspects support a reduction in blood pressure: diet and exercise. When it comes to diet, almost all studies point to a connection between salt consumption and high blood pressure. Patients who reduce the amount of salt in their diet or pay attention to the salt content of ready-to-eat foods can have a considerable positive influence on their blood pressure levels. Consistent and regular exercise is necessary to permanently lower blood pressure levels. Only isolated exercises do not have any effect, on the contrary, they strain the already susceptible body. Sports that lower blood pressure are those in which the patient strengthens or increases endurance and stamina. These include walking, running, cycling and swimming.Contact sports or so-called stop-start sports such as tennis should be avoided; sports with a high static load such as weightlifting, apparatus gymnastics, or rowing should also be critically evaluated.