Coarctation of the aorta
An aortic coarctation (ISTA) or coarctation of the aorta ( Coarctatio aortae ) is understood to mean the narrowing of the aorta (main body artery ) in the area of the aortic arch . It is a vascular malformation that occurs alone, but also in connection with congenital heart defects . It accounts for about six to eight percent of all congenital heart defects, is more common in men than in women, and often occurs with Turner syndrome (monosomy X).
There are two theories about the origin:
- decreased blood flow during the embryonic period in the ascending aorta or
- Dislocated tissue of the ductus arteriosus , which contracts actively and strongly soon after birth .
Traditionally, a distinction is made between preductal and postductal aortic coarctation based on the location of the stenosis in relation to the ductus arteriosus (Ductus Botalli). This classification has been partially abandoned today, since the two forms can merge into one another during the embryonic period ; However, due to differences in symptoms and prognosis, it is shown here.
Before birth, the ductus arteriosus diverts almost all of the blood coming from the right heart past the pulmonary arteries into the aorta. So there is a short circuit between the pulmonary and body circulation , in which the body circulation receives large amounts of blood from the pulmonary circulation. The lungs are not yet functioning at this time, so it would make no sense to give them a privileged blood supply. The ductus arteriosus usually closes at birth - the two circuits are now separated. The oxygenation of the blood takes place in the lungs, while the left heart drives it throughout the body.
also: infantile form of the ISTA
If the narrowing of the aorta is in front of the confluence of the Ductus arteriosus Botalli, the left heart must first fight against increased flow resistance due to the narrowed artery. In the case of severe constriction, the left heart can soon no longer cope with this load ( left heart failure ), and the blood also backs up into the lungs, from which it can no longer be “pumped out” - the result is shortness of breath ( dyspnoea ).
In such cases, the ductus arteriosus itself often remains open after birth and flows into the aorta after the stenosis. This leads to an admixture of venous blood into the aorta and thus the entire lower half of the body. This appears cyanotic (bluish discoloration), it can lead to prerenal kidney failure due to reduced and oxygen-poor kidney blood flow. A pulse deficit between the upper and lower halves of the body, which is otherwise typical for ISTA, may be absent in these cases - after all, the aorta receives blood from the right heart via the ductus arteriosus.
The preductal form of ISTA usually becomes symptomatic soon after birth and leads to an acute danger to the life of the newborn (see below). Hence the name "infantile form".
also: adult form of ISTA
If the stenosis is after the ductus arteriosus has passed, the blood can usually use alternative channels (collaterals) via the inner thoracic and intercostal arteries ( aa. Thoracicae internae and intercostales ). These are therefore expanded and show up in the X-ray as rib damage.
In this case there is an increased blood pressure in the upper half of the body, but this is not as high as in the preductal form and initially does not overload the left heart. The ductus arteriosus is also usually closed in this case, so there is no admixture of oxygen-poor blood into the body's circulation.
In this form, the aforementioned deficit between arm and leg pulses is typically found: the arms have high (increased) blood pressure with clearly palpable pulses, while the legs have relatively low blood pressure with weak pulses or pulses that cannot be detected at all.
The post-ductal form of ISTA often remains symptom-free for years and only shows up in school children, adolescents or early adulthood. Hence the name "adult form".
- hourglass-shaped (short and very narrow in one place)
- tunnel-shaped (longer narrowing with significantly more aortic parts before and after)
- long with little underdevelopment of the aortic arch
- pronounced underdevelopment of the entire aortic arch
A newborn baby can get into a critical situation in the first days or weeks of life due to coarctation of the aorta (especially preductal) in the course of the circulatory change. The lower half of the body with all internal organs ( kidneys , liver , intestines ) is poorly supplied with arterial blood due to the narrowing of the aorta . As a result of insufficient blood flow to the liver, it is not uncommon for excessive neonatal jaundice ( hyperbilirubinemia ) to be present. The increasing stress on the heart quickly results in cardiac shock symptoms with a pale-gray-pale appearance in the newborns. In advanced shock, there is kidney failure with a lack of urine output - this is often confirmed in retrospect by parents when asked. Since all of these symptoms can also occur in the context of a severe newborn infection, antibiotics are often first treated under this suspicion and valuable time is sometimes lost before the correct diagnosis is made by echocardiography and the life-saving administration of prostaglanders begins. During this time, a shock-related overacidification of the blood can develop (metabolic acidosis; arterial pH not infrequently below 7.0!), Which then usually causes permanent brain damage. Every doctor who treats newborns needs to be familiar with this clinical picture and, if the symptoms are suspicious, it is better to consult a pediatric cardiologist once too much rather than too late.
However, it is not that rare (especially with the postductal form) that an ISTA is only diagnosed in older children or in adolescence or adulthood. In these patients there are numerous bypass or collateral circuits as a result of the bottleneck. Especially the vessels of the ribs, in the shoulder area and the chest wall arteries can have enlarged enormously. Pronounced collateral circulation can cover up a high-grade ISTA, since the measured differences in blood pressure in the arms and legs can then also be small.
- Prenatally (prenatal) it is not uncommon for affected children to notice pronounced neck transparency ; however, the ISTA itself may be difficult to identify as it only manifests itself after the botallic duct has been closed.
- The first postnatal indication of an ISTA is the weak / absent femoral pulse (in the groin) on clinical examination. The lower half of the body appears cyanotic.
- During auscultation , a systolic ( spindle-shaped in phonocardiography ) sound is heard over the base of the heart and between the shoulder blades.
- The electrocardiogram shows u. U. left heart strain.
- The pulse deficit or the difference in blood pressure in the upper and lower extremities are certain signs of illness, especially in older children, adolescents or adults. The blood pressure is too high in front of the constriction and too low after the constriction.
- The long-term blood pressure measurement on arms and legs with determination of the absolute blood pressure peaks and the day-night rhythm.
- The echocardiogram is used, but u. U. not proving in the case of the newborn, e.g. B. with simultaneous atrial septal defect or ventricular septal defect .
- X-rays in the newborn usually only show an enlarged heart with pulmonary congestion. In adolescents and adults, rib damage as a result of the collateral circulation.
- The cardiac catheterization in the newborn is rarely indicated for the diagnosis of a sole ISTA, however, important if other heart abnormalities exist.
- The MRI (nuclear magnetic resonance imaging, MRI, NMR) allows a good representation of ISTA. The flow measurements make it possible to estimate the gradient and also to carry out a 3-D reconstruction.
- A 3-D reconstruction is also possible with spiral computed tomography .
The two last-mentioned examination methods are used for anatomical reconstruction in the case of additional aortic arch malformations or variations.
Both forms of ISTA require careful monitoring and therapy - if left untreated, preductal ISTA results in a mortality of 60–90% even in infancy. Rapid surgical correction is indicated here. The postductal form also leads to a reduction in life expectancy if it is correspondingly pronounced - the surgical correction is therefore also indicated here, despite the initially minor symptoms, and should be carried out by the age of 6 at the latest. A careful assessment and planning of the further course of action by qualified persons (pediatricians and pediatric surgeons) is therefore always necessary.
- The balloon dilatation with the cardiac catheter and possibly a stent implantation with which the constriction is kept open permanently.
Balloon dilatation is the method of choice for re-stenoses and older children.
- The operation (first performed by Clarence Crafoord in 1944) in which, in a short ISTA, the narrowed part is cut out and the ends are connected in the form of an end-to-end anastomosis .
In the case of a long ISTA, various surgical methods are used, which must be decided individually. The operation can be carried out without the use of the heart-lung machine , as the heart function is not affected.
- The drug therapy with antihypertensive agents.
- A prenatal treatment method ( maternal-fetal hyperoxygenation ) has been developed at the German Center for Fetal Surgery and Minimally Invasive Therapy (DZFT) for unborn babies in whom prenatal ultrasound examinations of their heart (fetal echocardiography) suspect the development of aortic coarctation . Here, the pregnant woman breathes in oxygen in a concentration of 45% over a mask in three sessions for three to four hours a day. The oxygen reaches the unborn child via the placenta and leads to an expansion of its pulmonary vessels. The resulting increased lung blood flow also reaches the aortic arch through the left heart. The treatment is carried out from the 34th week of pregnancy for about three to four weeks and leads to a significant increase in the size of the underdeveloped aortic arch in unborn babies with suitable conditions. In 2016, a prospective controlled randomized study on maternal-fetal hyperoxygenation was published, which demonstrated the effectiveness of the procedure using the example of unborn babies who were expected to have coarctation of the aorta requiring treatment after birth: without oxygen therapy, 75 percent of the fetuses examined had to go to their ISTA after birth surgery, after prenatal oxygen therapy only 20 percent.
Long term prospects
Patients are dependent on lifelong follow-up examinations, in particular the control and treatment of high blood pressure that may have developed after long-term use of the ISTA. Also on the Endokarditisprophylaxe has to be lifelong.
The life expectancy of an ISTA patient is to be regarded as normal today with early detection and therapy.
- S2k guideline for coarctation of the aorta by the German Society for Pediatric Cardiology (DGPK). In: AWMF online (as of 2013)
- Reinhard Larsen: Anesthesia and intensive medicine in cardiac, thoracic and vascular surgery. (1st edition 1986) 5th edition. Springer, Berlin / Heidelberg / New York et al. 1999, ISBN 3-540-65024-5 , pp. 334–338.
- Klaus Holldack, Klaus Gahl: Auscultation and percussion. Inspection and palpation. Thieme, Stuttgart 1955; 10th, revised edition, ibid. 1986, ISBN 3-13-352410-0 , pp. 184-187 and 196 f.
- Prenatal treatment of coarctation of the aorta in the DZFT (or interrupted aortic arch, underdevelopment of the left heart, left heart hypoplasia, coarctation)
- T. Kohl, K. Tchatcheva, R. Stressig, A. Geipel, S. Heitzer, U. Gembruch: Maternal hyperoxygenation in late gestation promotes rapid increase of cardiac dimensions in fetuses with hypoplastic left hearts with intrinsically normal or slightly abnormal aortic and mitral valves. In: Ultrasound in Med. 29, 2008, p. 92.
- Shi Zeng, Jiawei Zhou, Qinghai Peng, Wen Deng, Ming Zhang: Sustained maternal hyperoxygenation improves aortic arch dimensions in fetuses with coarctation . In: Scientific Reports . tape 6 , no. December 1 , 2016, ISSN 2045-2322 , doi : 10.1038 / srep39304 ( nature.com [accessed July 13, 2018]).