Idiopathic hypertrophic subaortal stenosis

Description:

Hypertrophic subaortal stenosis - a rare form of the hereditary hypertrophic cardiomyopathy which is generally mentioning an interventricular partition. Hereditary diseases: the mapped phenotypes). The last together with a front shutter of the mitral valve creates an obstacle to emission of blood from the left ventricle (LV).

Symptoms of the Idiopathic hypertrophic subaortal stenosis:

Complaints:
- Thorax pains (even at rest)
- Faints after an exercise stress owing to reduction of the LZh sizes and strengthening of obstruction, and also arrhythmia
- The heartbeat caused by atrial or ventricular arrhythmias
- An asthma at an exercise stress owing to disturbance of the diastolic distensibility of a myocardium causing an overload of LP and a small circle of blood circulation.
Survey of patients:
- Coloring of integuments is not changed
- The apical beat is usually not displaced (sometimes it is displaced lateralno), but strengthened and can be double
- Quickly increasing dicrotic pulse on carotid arteries
- In a terminal phase - signs of increase in venous pressure: stretching of jugular veins, hypostases of shins, an exudate in pleural cavities, ascites.
Auscultation:
- Rough systolic noise with epicenter in 3 and 4 intercostal spaces on the left edge of a breast. Unlike a valve stenosis of an aorta, noise does not extend to a neck. At some patients define noise of the mitral regurgitation caused by deformation of the valve. The noise - blowing, better listened on a top, extending to the area of an axillary hollow
- Systolic noise amplifies when performing test of Valjsalva, in a standing position and at amyle nitrite inhalation, weakens in prone positions, squating, at a passive raising of a leg or inflation of the cuffs imposed on both hands (tranzitorny occlusion of peripheral arteries from the outside).
- Pulse and ABP do not change.

Reasons of the Idiopathic hypertrophic subaortal stenosis:

- Hemodynamic disturbances are caused by a considerable hypertrophy of an interventricular partition
- During a systole when blood passes the narrow site between a partition and a front shutter of the mitral valve, the zone of low pressure (Bernoulli's effect) is created. Occur the shift of a front shutter of the mitral valve to a partition and narrowing of the taking-out path of LZh
- Extent of obstruction of the taking-out path is individual and can change at each specific patient from time to time
- The states increasing the LZh sizes (increase before - and postloadings), promote removal on bigger distance from each other of a partition and
front shutter of the mitral valve also reduce extent of obstruction
- The states reducing the LZh sizes or reducing blood-groove speed (dehydration, drugs with positive inotropic action), raise extent of obstruction
- Obstruction of the taking-out path can cause a secondary hypertrophy of walls of a ventricle, but thickness of a hypertrophied partition will always be more than thickness of any of three free walls of a ventricle
- Decrease in elasticity of LZh leads to delay of its filling owing to what pressure in the left auricle (LA) and a small circle of blood circulation increases.

Treatment of the Idiopathic hypertrophic subaortal stenosis:

Therapy of a subaortal hypertrophic stenosis is directed to decrease in contractility of LZh, increase in its volume, elasticity, and also decrease in extent of obstruction of an output path. Unlike treatment of an aortal stenosis, conservative therapy as operations are very traumatic prevails and do not prolong life of patients.

Medicinal therapy.
- B-adrenoblockers, for example propranolol (анаприлин) to 320 mg/days
- Do not recommend purpose of B-adrenob-locators with sympathomimetic action (for example, Pindololum).
- Blockers of calcium channels (instead of propranolol). Choice drug - verapamil
- It is necessary to be careful at heart failure since its aggravation is possible
- It is rather contraindicated at a paroxysmal night asthma, a sinus bradycardia and AV to blockade (without electrocardiostimulation).
- Antibiotics (penicillin, aminoglycosides, cephalosporins) - for prevention of an infectious endocarditis.
Contraindications:
- The drugs reducing preloading (for example, nitrates and diuretics) and by that reducing the LZh size
- Drugs with positive inotropic action (cardiac glycosides, catecholamines) which are aggravating obstruction of an output path and not reducing high end diastolic pressure
- Cardiac glycosides and diuretics apply carefully only at late stages of a disease when there is ventricle dilatation
- Vazodilatatora, increasing a pressure gradient in an output path and provoking reflex tachycardia, worsen filling of a ventricle in a diastole.
Surgical treatment:
- The indication to operation: a severe disease, resistant to medicamentous therapy, with a pressure gradient between LZh and an aorta more than 50 mm hg.
Types of operations.
- A myomectomy - reduction of thickness of a hypertrophied interventricular partition from LZh
- Prosthetics of the mitral valve allows to improve filling of LZh, to reduce pressure in LP and to increase cordial emission
- Results of operations: improve a condition of 70% of patients.