Open atrioventricular channel

Description:

The open atrioventricular channel (AVK) is characterized by an underdevelopment of partitions, adjacent to atrioventricular valves, and anomalies of valves. Thus, pathology includes primary defect of an interatrial partition, defect of a stitched part of an interventricular partition and defects of formation left and right atrioventricular valves. As extent of disturbance of development of data of structures can be various, there is the whole range of deviations from which allocate a partial (incomplete) form, an intermediate and full form of the atrioventricular channel.
Frequency of defect makes 0,25 for 1000 live-born, about 4% among all VPS and 6% among critical VPS.

In the period of a neonatality hemodynamic problems develop, as a rule, at children with a full form of the atrioventricular channel which is considered in the present section.

Defect includes primary defect of an interatrial partition, defect of an interventricular partition under atrioventricular valves and the general ring of atrioventricular valves at once. Approximately 50% of patients have a Down syndrome. In 13 — 18% of cases of AVK it is combined with other pathology of heart (Fallo's tetrad, an atresia or a stenosis of a pulmonary artery, aorta coarctation, an atrial izomerizm, etc.).

Anatomy. At this defect the message among themselves of all four cameras of heart as auricles connect to ventricles the general opening is possible. The general valve in most cases has five shutters: front bridge-like, back bridge-like, right and left muralny shutters and right anterosuperior shutter. In some observations the opening of the general valve falls preferential into one ventricle (dominance of the left or right ventricles), the second ventricle in such options happens гипоплазирован. Papillary muscles of a left ventricle can be located abnormally closely to each other or to be presented by the only muscle.

Symptoms of the Open atrioventricular channel:

Honor partially open AVK in 3 ра­ for more often occurs at female persons. Clinical proyavyoleniye of defect depend both on size DMPP, and on degree of manifestation of insufficiency of the mitral valve. At umeyorenny degree of insufficiency of the .mitralny valve the course of a disease approaches that at the isolated DMPP whereas at a considerable regurgitatsin from the first days and months of life a condition of patients heavy, poyovtorny SARS, symptoms of heart failure both on left-are noted lag in physical and motor development, and on right ventricular type with congestive wet rattles in lungs, the cordial hump early develops.

At a palpation the apical beat is strengthened, on a top of a sleyov at / t of patients is defined systolic trembling, at auscultation are listened two different in a timbre and localization of noise: on a top — systolic noise of insufficiency мит­ the rolled valve with conductivity in left axillary об­ласть; in the second and third mezhreberye at the left — systolic noise of DMPP. If because of features of splitting of the mitral valve dumping of blood is directed more in right, than in left, the auricle, systolic noise of insufficiency of the mitral valve irradiates preferential on the heart basis. The systolic noise of insufficiency of the three-leaved valve connected with splitting of its shutter, or meeodiastoliche-sky noise of its relative tenoz (the increased blood stream) quite often are not defined as are blocked by other more intensive noise. The II tone over a pulmonary artery is split; uniform II tone as a symptom of high pulmonary hypertensia, vstreyochatsya seldom.

The ECG considerably helps with establishment of the diagnosis of AVK. First of all it concerns a deviation of an elektriyochesky axis of heart to the left which is noted at 60 — 70% of patients with the AVK incomplete form and is connected with anomaly of the carrying-out system of heart; jLoAQRS from — 20 to — 60 °, is more rare to — 130 °. The combination of mitral insufficiency to such levogrammy indicates existence of open AVK. In rare instances the electrical axis is rejected to the right. Other feature is the overload of a right ventricle what is expressed by increase in amplitude of teeth/? With, the QRS form in the form of rSR, rR are possible signs of an overload of the left auricle, a left ventricle (at patients with the prevailing insufficiency of the mitral valve without pulmonary hypertensia); lengthening of an interval of PR. At pulmonary hypertensia on an ECG signs of a sistoliyochesky overload of a right ventricle appear. Adult patients have vozyomozhna attacks of a Bouveret's disease.

On FKG II tone over a pulmonary artery is split (0,03 — 0,06 c), its pulmonary component is strengthened, are fixed III and IV rutting of heart. In the second and third mezhreberye rhomboid or spindle-shaped systolic noise, zaniyomayushchy 2/z or all systole (noise of DMPP) is defined; on a top — sisyotolichesky noise of insufficiency of the mitral valve, svyazanyony with the I tone (decreasing or taenioid). At a half of patients on a top of heart are registered mesodiastolic or presystolic noise of small amplitude.

On the roentgenogram at partially open AVK the pulmonary drawing is strengthened both on arterial, and on a venous bed (a left ventricular failure sign at considerable mitral регургитацин). The legochnoyarteriya arch moderately vyyobukhat. The shape of heart can be various depending on the extent of defect and expressiveness of mitral insufficiency. At small DMPP manifestations of a mitral neyodostatochnost prevail, increase in the left auricle, left ventricle in this connection the top of heart is shipped in a diafyoragma is noted, the cardiomegaly is possible (the shape of heart reminds tayokovy at a dilatatsionny cardiomyopathy). Increase in the right auricle is characteristic of big DMPP.

At an echocardiographic research signs of primary DMPP are found in children with partially open AVK (an echo signal break from a partition); anomalies of the mitral valve (rapprochement of a fibrous ring of the valve and a mezhzheludochyokovy partition, an echo from a front shutter is traced to a front wall of an aorta, additional echo signals from anoyomalno the chords of the split lobby of a mitral shutter attached to an interventricular partition, characteristic form of motion of a front shutter — during a diastole it as if sticks to an interventricular partition); signs of an izmeyoneniye of the tricuspid valve (the beginning of a systolic segmenyot of a curve of the valve directly over an interventricular peyoregorodka); signs of a volume overload of a right ventricle. Accessory signs of defect are narrowing of a vyvodyony path of a left ventricle, dilatation of the right departments of serdyoets, paradoxic movement of an interventricular partition. At a two-dimensional echocardiographic research in a projection of 4 cameras from a top primary defect of an interatrial partition comes to light, the interventricular partition and the tricuspid valve are not changed. In the short section of the left zheluyodochk at the level of the valve splitting of a front mitral shutter is defined.

At introduction of a catheter to a right ventricle during a zondiyorovaniye of cardial cavities it easily passes from the right day of presulfurs through DMPP in the left auricle and a left ventricle. Povyyoshenny saturation of blood oxygen is noted at the level of a prayovy auricle and increases further in a right ventricle and a pulmonary artery (a dumping sign at two levels). At chasyotichny open AVK indicators of pulmonary pressure and all-pulmonary resistance normal or moderately poyovyshena, the pressure gradient between a pulmonary aryoteriya and a right ventricle, as is found at DMPP (a functional pulmonary stenosis).

The left-side vent-rikulografiya revealing a typical sign of otkryyoty AVK — narrowing and deformation of outflow tracts from the left zheyoludochk (a symptom of a goose neck) testimonial of a rasshchepyoleniya of a shutter of the mitral valve has special diagnostic value. From a left ventricle a contrast agent comes to the right and left auricles.

Reasons of the Open atrioventricular channel:

This syndrome is a malformation, developing vnutriutrobno at laying of bodies to cardiovascular system.

Treatment of the Open atrioventricular channel:

The natural course of defect is defined by the DMPP sizes and expressiveness of mitral insufficiency. Severe forms prove in the first months and years of life and demand early surgical correction. At easy forms of defect of the complaint can be absent, and the disease to be shown only by auskultativny symptomatology; patients live up to adult age and keep working capacity is similar to how it is observed at secondary DMPP ediyonichny cases when patients lived up to 60 and more years Are described. Odnayoko most of patients without operation die to 20 — 30-letneyogo age of heart failure, a pulmonary gnpertenziya, a bacterial endocarditis, disturbances of a cordial rhythm.

Indications to operation. Because pulmonary гнпертспзня at partially open AVK it is observed seldom. it is reasonable to perform corrective operation in 6 — 10 years when it is possible to come into optimum results функционально­го fortune of the mitral valve in the remote terms. Protivoyopokazany to operation is acute bacterial endokaryodit.

Operation consists in recovery of integrity of a peredyony shutter of the mitral valve that is reached by imposing of separate seams; primary DMPP is closed by a patch. If necessary plastic surgery and on the tricuspid valve can be executed. The need for prosthetics of the mitral valve arises quite seldom and is caused most often by the accompanying pathology — the double mitral valve.

The surgical lethality fluctuates from 3,7 to 6,7% at the isolated defect form [Bukharin V. A., Podzolkov V. P., 1982; Falkovsky G. E., Buzinova L. A., 1986; Бураковскнй V. I., etc., 1989] and 14% at a combination to other VPS | Studer M. et al., 1982]. Lethal outcomes are more often noted at the children of early age with small body weight having heavy mitral insufficiency and a cardiomegaly. It is possible to distinguish heart failure because of inadequate correction of the mitral valve, narrowing in a subaortal path from the complications conducting by a lethal outcome, a total atrioventricular block, prosthetics of the valve at babies, disturbances of a cordial rhythm.

The long-term results of operation at partially open AVK, despite preservation at many patients of residual noise of insufficiency of the mitral valve, as a rule, horoyoshy. Survival of patients in 20 years after operation sostavyolyat 94%, and only 5% from them demand repeated a pmeshatel of a stvo on the mitral valve.