1.08.2012

AORTIC STENOSIS

Posted on 1:02 AM by know about heart


Aortic stenosis means, aortic valve fails to open completely and thus the forward flow of blood is impaired. Three semilunar cusps or leaflet form aortic valve. If there is an abnormality in aortic valve due to any disease, it fails to open perfectly and aortic stenosis occurs.
Causes of aortic stenosis:
i)                   Infants, children, adolescents:
§ Congenital aortic stenosis
§ Congenital subvalvular aortic stenosis
§ Congenital supravalvular aortic stenosis
 ii) Young adults to middle aged:
             § Calcification and fibrosis of congenitally bicuspid aortic valve
             § Rheumatic aortic stenosis
iii) Middle-aged to elderly:
            § Senile degenerative aortic stenosis,
            § Calcification of bicuspid valve
            § Rheumatic aortic stenosis
Clinical feature of Aortic stenosis:
Symptoms:
   § Mild or moderate aortic stenosis is usually asymptomatic.
   § Exertional dyspnoea
   §  Angina
  § Exertional syncope
  § Sudden death
  § Episodes of acute pulmonary oedema
Normal heart
Signs:
§ Ejection systolic murmur
§ Slow-rising carotid pulse
§ Narrow pulse pressure
§ Heaving apex beat (LV pressure overload)
§ Signs of pulmonary venous congestion (e.g. crepitations)
Investigations:
i)                   ECG:
§ Left ventricular hypertrophy (usually)
§ Left bundle branch block
    ii) Chest x-ray:
§ May be normal. Sometimes enlarged left ventricle and dilated ascending aorta on PA view, calcified valve on lateral view.
     iii) Echo: Calcified valve with restricted opening hypertrophied LV.
     Doppler:
§ Measurement of severity of stenosis
§ Detection of associated aortic regurgitation
      v) Cardiac catheterization:
§ Mainly to identify associated coronary artery disease
§ May be used to measure gradiant between LV and aorta


Treatment
General Measures
Prophylaxis against infective endocarditis and recurrent rheumatic fever, if applicable, is indicated.

Medication (Drugs)
AS is a mechanical limitation, and medical treatment has little role in preventing the progression of the disease process or in the treatment of the outflow obstruction once symptoms develop. However, with the onset of LV systolic dysfunction, the use of intravenous inotropic agents may be advocated for acute decomposition.
Contraindications
Vasodilators are relatively contraindicated in severe AS.
Surgery
Indications for Aortic Valve Replacement
  • Symptomatic patients
    • AVR improves survival in patients with depressed as well as normal LV function.
    • Depressed LV function is secondary to either afterload mismatch or depressed contractility. In the latter, the improvement in LV function and symptoms may not be complete.
  • Asymptomatic patients
    • The risks of surgery and prosthetic valve complications outweigh the benefits of preventing sudden cardiac death and prolonged survival in asymptomatic patients. An exercise test may be useful in these patients to assess functional limitation.
  • Prophylactic AVR
    • Patients with severe AS undergoing coronary artery bypass grafting or other valve replacement should undergo AVR as well.
    • Consideration for AVR in patients with moderate AS if undergoing coronary bypass grafting, other valvular surgery, or aortic surgery
    • This issue is controversial in patients with mild AS.
Aortic Balloon Valvotomy
  • Percutaneous balloon dilatation offers little benefit for adults with calcific AS or with secondary calcification of a bicuspid aortic valve.
  • This procedure is reserved for patients with serious severe comorbidities that are not candidates for AVR, patients requiring urgent noncardiac surgery, and as a bridge to AVR.
Follow-Up
Prognosis
  • Prognosis is similar to that for age-matched normal adults during the asymptomatic period.
  • Development of symptoms is associated with a grave prognosis, showing a 2-year survival rate of ~50% without surgical intervention.
Complications
  • Congestive heart failure
  • Sudden cardiac death
  • Atrial arrhythmias
  • Infective endocarditis
  • Systemic calcium embolism
  • It can be associated with intestinal arteriovenous malformation.
  • Prosthetic valveâ“related complications

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