Bicuspid Aortic Valve: Dysfunction, Complications, Diagnosis

Aortic valve is a semilunar valve: A tricuspid valve. Cusps in a normal aortic valve include anterior, left and right. At the site of left coronary sinus - Left coronary artery. At the site of the right coronary - Right coronary artery. At Non coronary cusps - No coronary artery. In the bicuspid aortic valve, 2 cusps get fused. Based on the fusion of cusps and position of raphe, they are divided into

• Type 1: Fusion of right and left coronary cusps.
• Type 2: Fusion of right coronary cusps. The right coronary combines with non-coronary cusps.
• Type 3: Left and non-coronary cusps get fused.

Dysfunction of Bicuspid Aortic Valve 

Aortic Regurgitation

• Seen around 15%
• Valve and tissue prolapsed.
• Tissue redundancy is reduced.
• Valves prolapse.

Aortic Stenosis

• Seen around 75%
• More prominent in valves without tissue redundancy.
• Stenosis develops more rapidly.
• Aortic cusps are asymmetrical or in anteroposterior position.
• Increased strain in systole is caused due to asymmetry.
• High stress on raphe.
• Systolic flow patterns are affected.
• Valves are prone for accelerated calcium deposition.

Natural History in Bicuspid Aortic Valve

Children develop severe AS/AR. In adults, there is no valvular involvement. BAV is associated with aortic dissection. In elderly, incidental detection by 2D echo. Type 2 BAV is common in young individuals. Type 2 – Right coronary cusp fuse with non-coronary cusp. Associated with accelerated by aortic stenosis or aortic regurgitation. Symptoms:

• Syncope
• Angina
• Dyspnea Or symptoms from aortic regurgitation Palpitations, dyspnea, syncopal attack, anginal pain.

Complications associated with Bicuspid Aortic Valve 

Development of ascending aortic aneurysm. Due to medial degeneration of ascending aorta.

Coarctation of aorta

Less frequently seen.

Aortopathy

• Enlargement of ascending aorta along greater curvature
• Type 1 BAV
• Mechanism of development of aortopathy in case of bicuspid aortic valve-Due to increased Hemodynamic stress

Aortic dissection

Commonly seen in ascending aorta

Shone complex.

4 components

• Supravalvular mitral membrane-It can lead to mitral stenosis.
• Left ventricular outflow tract obstruction: Due to presence of membrane at the level of left ventricular outflow tract which gives the picture of Aortic stenosis.
• Presence of Coarctation of aorta: it reduces blood flow.
• BAV

Also Read: Cardiac Channelopathies: Sudden Cardiac Death in the Young

Diagnosis of Bicuspid Aortic Valve

Clinically

• AS: syncope, angina, and Dyspnea
• On auscultation - Heaving apical impulse
• Ejection systolic murmur
• Signs of AS/AR or Coarctation of aorta, Coarctation of aorta: radio femoral delay and continuous murmur

ECG

• Left ventricular hypertrophy.
• SV1+RV6> 35mm
• Volume overload, deep Q waves
• ST segment depression
• Asymmetrical T wave inversion

Transthoracic echocardiography

• Parasternal short axis view permits direct visualisation of valve cusps.
• Triangular opening shape or Mercedes- Benz sign.
• In BAV, fish mouth appearance is seen. Also seen in rheumatic mitral stenosis
• Fish mouth appearance - Seen in systole of left ventricle.
• Presence of vegetations on the valves
• Look for development of systolic dysfunctions.
• To Visualize part of the root of the ascending aorta.

• In arteriography, aortic root injection is given.
• A Doming valve can be seen, and annulus is measured.
• Transoesophageal echocardiography is useful in poor transthoracic windows.
• Full length aortopathy can't be visualised.
• Descending aorta can't be seen.
• CT/MRI: Visualise entire aortopathy. Gives a clear picture of BAV. Also detects calcification.

Treatment - Intervention in BAV 

• Open surgical valvotomy
  • For aortic stenosis
• Balloon valvuloplasty
  • Treatment of choice
  • Done to relieve aortic stenosis.
• BAV may progress to severe AS/AR by the 5th decade of life so to prevent it surgical interventions are done. Has good temporary relief of stenosis.

Balloon Valvuloplasty

• The basic objective is to relieve aortic stenosis without causing AR.
• Restores normal LV function.
• Advantage - minimally invasive.
  • A catheter-based procedure.
  • Less mortality and morbidity
• Access is through the femoral artery.
• Approach is retrograde femoral artery approach.
  • The carotid approach can also be opted.
• Other approaches in newborn are:
  • Umbilical artery approach Done in critical AS.
  • Axillary artery approach
  • Trans venous antegrade approach
• Incidence of post procedural AR is less.

Indications of Balloon Valvuloplasty

• Class 1 indications
  • Critical AS in newborns regardless of gradient
  • In infants and children with LV dysfunction with any gradient.
  • Left ventricular systolic gradient >50 mmHg. Individuals are asymptomatic.
  • Gradient >40 mmHg. C/F are angina and syncope.
  • ECG shows ST-T changes at rest or with exercise.
• A low profile Tyshak mini balloon is used.

Complications of Balloon Valvuloplasty

• Post procedural AR. Seen in 25% of elderly high-risk elderly individuals.
• Femoral artery compromise
• Thromboembolic events -Give anticoagulants.
• Cardiac arrhythmias. Development of complete heart block
• Damage to mitral valve during transvenous antegrade approach
• Perforation to ventricular myocardium

Surgical Aortic Valvuloplasty

Absolute indications: Single ventricular abnormality and its repair. Small aortic annulus or supra valvular AS or Coarctation of aorta

Relative indications: Presence of dysplastic aorta. Aortic valve repair and plan for replacement if the individual is refractory.

Exercise in BAV

• Severe AS/AR with LVEDD >66mm shouldn't participate in exertional activity.
• Dilated Aortic roots >45mm with or without Aortic valve disease. Can play low intensity sports.
• No restriction – when diameter of aorta< 40mm

Also read: High-yield NEET SS Medicine Neurology Questions

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