The stratifying aortic aneurysm

Description:

The stratifying aortic aneurysm (dissection of the aorta) arises when blood from a gleam of an aorta gets in its wall, forming the so-called false channel and extending on its course to various length. This state arises sharply and is zhizneugrozhayushchy. Without treatment of 25% of patients die within 24 hours, 50% - within 48 hours and 1 year live only 10%.

At the present stage of development of medicine thanks to improvement of diagnostic methods and treatments the stratifying aortic aneurysm turned from almost absolutely fatal process into pathology from 75% 5-year survival.

Symptoms of the Stratifying aortic aneurysm:

The original classification of stratification of an aorta by DeBakey allocating three of its types is still widely used:

  1. the type - stratification begins on the ascending aorta and extends distally to an arch and, is more often, farther on the descending aorta;
  2. the type - stratification begins and limited to the ascending aorta;
  3. the type - stratification begins and limited to the descending aorta, with two subtypes: stratification comes to an end above a diaphragm and stratification extends below a diaphragm.


Based on distinctions in a clinical current and the forecast, Daily offered the alternative classification allocating the following two types of stratification of an aorta: Type A - stratification,
involving the ascending aorta (type I and II on DeBakey). Type B - the stratification limited to the descending aorta (type III on DeBakey). Stratification is considered acute if since its emergence there passed less than two weeks, chronic - if more than two weeks.

The leading manifestation of acute stratification of an aorta is the sudden attack very much of a megalgia in a breast (in 90% of cases). Most often pain is localized on the front surface of a thorax and irradiates in interscapular space. If pain is limited to the front surface of a thorax, stratification of the ascending aorta is the most probable and if pain is localized only in spin, stratification of the descending aorta is the most probable.

Stratification of an aorta clinically can be also shown by syncopal states, the acute heart failure which is usually caused by a cardiac tamponade, or acute insufficiency of the aortal valve, DVS a syndrome. Besides, various ischemic syndromes as a result of disturbance of blood circulation on the arteries compromised with stratification can be observed. For example, a myocardial infarction, acute ischemia of a brain, a renal failure, renovascular hypertensia, the ischemia of a spinal cord caused by a prelum of a front spinal artery with motor and touch deficit, intestines ischemia, ischemia of extremities, absence or weakening of pulse on extremities. Physical inspection
By means of simple methods of physical inspection it is possible to reveal the increase in arterial pressure characteristic of many patients with the stratifying aortic aneurysm. In case of an acute heart failure, including at a cardiac tamponade, the lowering of arterial pressure, tachycardia, increase in the central venous pressure, stretching of cervical veins, paradoxical pulse come to light. Absence or weakening of pulse which is criterion of stratification of an aorta at stratification of the ascending aorta is observed at 50% of patients, and at stratification of the descending aorta - at 10-15%.

Aortal insufficiency is found in most of patients with stratification of the ascending aorta. Retrograde distribution of stratification of an arch or the descending aorta is more rare can involve the aortal valve, but in general, she points to the beginning of stratification in the ascending aorta. If acute considerable aortal regurgitation leads to a left ventricular failure, increase in the pulse pressure which is usually associated with chronic aortal insufficiency is not observed. The outside rupture of the stratifying aneurism in the left pleura causes dullness at percussion of lungs and weakening of respiratory noise.

Neurologic deficit in the form of a hemiplegia can be caused by a skomprometirovannost of carotid arteries, and in the form of a paraplegia - a front spinal artery. Considerable ischemia of extremities is shown by loss of deep tendon jerks, anesthesia and paralysis.

The reasons of the Stratifying aortic aneurysm:

The standard mechanism of stratification of an aorta penetration of blood from its gleam in copper through a gap in an intima is considered. Cross oriented rupture of an intima in 61% of cases is found in the point located several centimeters above the aortal valve in 16% - between an otkhozhdeniye of the left subclavial artery and ligamentum arteriosum. Less typical places of a rupture of an intima are the descending aorta (9%), an aortic arch (8%) and a ventral aorta (2%).

Also the possibility of development of stratification of an aorta after formation of primary hemorrhage in copper from vasa vasorum already with a secondary rupture of an intima is acknowledged. This mechanism is considered responsible in 4% of cases of detection of a hematoma in an aorta wall, however without disturbance of integrity of an intima. The rupture of an intima is not found also in 13% of cases of stratification of the descending chest or ventral aorta. At the same time any pathological process responsible for development of a rupture of an intima or hemorrhage in copper, do not find.

Atherosclerosis was not an accurate etiological factor of stratification of an aorta and concerning its role in it still there are disagreements. On the one hand, the place of the most frequent and crushing atherosclerotic defeat - a ventral aorta is the site of the most rare emergence of stratification of an aorta, and ruptures of an intima in the site of an aorta affected with atherosclerosis are found less than in 5% of cases. On the other hand, Wilson and Hutchins which found insignificant, but reliable dominance of atherosclerotic defeat in patients with the stratifying aneurism against a control group of persons do not exclude even in these cases of its probable role in stratification.

Pathological processes in a mussel (a necrosis, elastinovy fragmentation and fibrosis) were studied by histologic methods in a normal aorta out of signs of external defeat, at elderly people, patients with an aortal stenosis, at Marfan's syndrome and the stratifying aortic aneurysm. Reliable dominance of these processes at the stratifying aortic aneurysm was not revealed though at it they also were expressed more considerably. Vesical медионекроз at patients 40 years with the stratifying aortic aneurysm in classical work of Schlatmann and Becker are younger (cystic medionecrosis) it was the only process which frequency of occurrence did not increase with age. However the alternative opinion exists and about it as other researchers managed to show progressing of a vesical medionekroz with age and at arterial hypertension. Though vesical медионекроз often meets at Marfan's syndrome, some patients with stratification of an aorta at Marfan's syndrome have no vesical medionekroz.

At the present stage only the contributing factors of stratification of an aorta are accurately defined so far. The most important among them is the arterial hypertension (AH). Clinically obvious to AG or AG was present at the anamnesis in 92% from 463 autopsies analyzed in classical work of Hirst of 1958. According to other authors this percent hesitates from 52 to 82%. The second for prevalence contributing factor are congenital anomalies of the aortal valve. The two-fold valve in clinic of Mayo was found in 11,4% of cases of stratification of an aorta. Other processes associated with stratification of an aorta are Marfan and Elersona-Danlos's syndromes, pregnancy, aorta coarctation, аортальнй a stenosis, Turner's syndrome recuring a polychondritis. Even less frequent associations include giant-cell arteritis (temporal arteritis, Horton's syndrome), a syphilitic aortitis and the use of cocaine.

On the special place there are iatrogenic reasons of stratification - heart catheterization, installation of system for intra aortal balloon counterpulsation through a femoral artery, performance of balloon angioplasty for elimination of coarctation of an aorta. Cardiovascular operative measures are the rare reason of stratification of an aorta. According to the Massachusetts central hospital of the USA they are observed in 0,16% of cases (24 cases on 14 877 operations), but according to clinic of Mayo this percent can reach 11,6%. Thirds on occurrence frequency as the reason of stratification of an aorta after AG and the two-fold aortal valve cardiac interventions act.

Treatment of the Stratifying aortic aneurysm:

At the present stage the following approach to treatment of patients with the acute stratifying aortic aneurysm is accepted. All patients with the diagnosis of the acute stratifying aortic aneurysm are hospitalized to the intensive care care unit of specialized cardiac clinic where medicamentous therapy begins, and indications to the emergency operative measure are estimated.

The purpose of medicamentous therapy is prevention of further stratification and an outside rupture of an aorta. Patients without acute left ventricular failure are recommended to reduce contractility of a myocardium, heart rate and arterial pressure to minimum possible values when perfusion of vitals is still provided, and there are under control a mocheotdeleniye and functions of the central nervous system. A classical medicamentous combination for this purpose intravenous infusion of Sodium nitroprussidum with b-adrenoblocker is considered (propranolol, эсмолол, лабеталол). Co-administration of these drugs is obligatory since Sodium nitroprussidum increases myocardial contractility which is undesirable, leveled by b-adrenoblocker. Trimetafan also effectively reduces the arterial pressure and contractility of a myocardium, but because of the tachyphylaxis developing to it it is considered drug of the second order. At contraindications to b-adrenoblockers (bronchial asthma) intravenous forms of blockers of calcium channels (nifedipine) can be used though about it in literature there are few data.

The second purpose of medicamentous therapy at a presurgical stage is adequate anesthesia. Pain at the stratifying aortic aneurysm very intensive also demand introduction of narcotic analgetics. Not stopped pains are considered as a sign of the continuing stratification and are the indication to the emergency operative measure.

In parallel with the carried-out medicamentous therapy it is required to estimate indications to the emergency operational treatment. The following is considered as these indications: stratification of the ascending aorta, an acute heart failure, signs of an outside gap (a hemopericardium, a hemothorax), disturbance of a blood-groove on aorta branches, stratification progressing signs (not stopped pain, increase in the sizes of aneurism). The first feature of operations the stratifying aortic aneurysms is that they emergency as each hour of their delay increases probability of death of the patient. On training of the patient, as a rule, there is practically no time left. At the I type of stratification which is not demanding prosthetics of an aortic arch, and the II type the following operations are carried out.

Bentall's operation consists in depletion of the aortal valve, prosthetics of the aortal valve and the ascending aorta (from an intima) one combined prosthesis with reimplantation of coronary vessels in a prosthesis. In case of the minimum aortal insufficiency or when it is possible to keep the valve by plastic surgery, suprakoronarny prosthetics of the ascending aorta is carried out.

Both operations long, labor-consuming are also carried out in the conditions of artificial circulation. Big blood losses are typical for them. Especially carefully at these operations it is required to carry out protection of a myocardium,
using standard saline cardioplegic solutions and alternative techniques of a cardioplegia - blood and with perftorany. The patient olazhdatsya up to the temperature of 24-260C that in combination with big blood loss and long artificial circulation gives a large number of complications after operation, including development of DVS of a syndrome. When involving in stratification of an aortic arch (the I type) its prosthetics with reimplantation of vessels of the head and neck (a brachiocephalic trunk, the left general sleepy, left subclavial) is carried out. At the same time the full stop of blood circulation (cardiac arrest) and retrograde perfusion of a brain through internal jugular veins is used. In these conditions of one of the main tasks protection of a brain is that is reached by the general deep hypothermia to 12-140C and use of the drugs reducing the need of a brain for oxygen (пропофол, Seduxenum). Long perfusion, full stop of blood circulation and retrograde perfusion adversely affect functions of the central nervous system, leading to various complications in the postoperative period, from insignificant encephalopathy to a deep coma and wet brain. For correction of these states use symptomatic therapy, similar to medicamentous protection of a brain at operations with retrograde perfusion.

At correction of stratification of the descending chest aorta (Ш stratification type) prosthetics of the descending chest aorta with reimplantation of intercostal vessels in a prosthesis is carried out. These are the heaviest operations. Their feature is imposing of the shunt bypassing the place of prosthetics of an aorta from a full stop of blood circulation for the period of its imposing with retrograde perfusion of a brain and also a hypothermia to 12-140 C. For ensuring surgical access (side, but not median as in the previous cases), the one-pulmonary intubation is carried out, protection of a brain is required, as in the previous case, plus bodies of a chest and abdominal cavity, krovosnabzhayemy of the allocated site of an aorta.