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Prosthetic Heart Valves

Title               

Ñ    Prosthetic Heart Valves

Definition

Types

Ñ    Mechanical:

Ball and cage

Tilting disc

Bileaflet

Ñ    Biological:

Plastic stent, cusps porcine aortic valve or pericardium

Ñ    Aortic homograft:

Valve mounted on a ring of native aortic root

Pathogenesis

Indications for valve replacement

Ñ    Severe regurgitation or stenosis of native valve

Pathophysiology

Ñ    Pressure gradient across prosthetic valves is high

Ñ    Rigid mitral valve ring interferes with ventricular function

Clinical Features

History

Past Illnesses

Ñ    Valve disease

Examination

IS

Ñ    Sternotomy scar

CVS

Ñ    Closing click:

Mechanical valves, all

Ñ    Opening click:

Mechanical valve, ball and cage

Complications

CVS

Ñ    Limited prosthetic function

Ñ    Prosthetic valve dysfunction

Ñ    Left ventricular disease

Ñ    Infective endocarditis

Limited prosthetic function

Ñ    Valve too small:

Severe haemodynamic disturbance

Ñ    Valve too large:

·          Mitral valve:

Subaortic stenosis

·          Aortic valve:

Obstruction between the ball and the aorta

Prosthetic valve dysfunction

Ñ    Strut fracture

Ñ    Calcification

Ñ    Perforation

Ñ    Detachment

Ñ    Thrombosis:

Acute or chronic

Ñ    Paraprosthetic regurgitation

Prosthetic valve dysfunction presents with signs of heart failure

Left ventricular disease

Ñ    Present preoperatively

Ñ    Damage during operation

Ñ    Discrepancy between size of valve and site of insertion

Ñ    Rigid metal ring interferes with ventricular function

Ñ    Coronary emboli

Signs of heart failure

Infective endocarditis

Ñ    Signs of infective endocarditis

HS

Ñ    Haemolysis:

Increased risk if there is a paraprosthetic leak

CNS

Ñ    Thromboembolism

Investigations

Fluids

Blood

Haematology

Ñ    Anaemia:

Haemolytic

Endocarditis

Other causes

Biochemistry

Ñ    Elevated bilirubin:

Haemolysis

Ñ    Elevated lactate dehydrogenase:

Haemolysis

Ñ    Decreased haptoglobin:

Haemolysis

Urine

Haematology

Ñ    Haematuria:

Endocarditis

Biochemistry

Ñ    Haemosiderinuria:

Haemolysis

Imaging

Contrast Studies

Ñ    Cardiac catheterisation:

Prosthetic valve dysfunction

Ultrasound

Ñ    Echocardiogram:

·          Transthoracic or transoesophageal:

Prosthetic valve dysfunction

Heart failure

Endocarditis

Management

Support

Drugs

Ñ    Anticoagulation:

Mechanical valves

Arrhythmia

Surgery

Ñ    Severe complications:

Valve replacement may be necessary

Prevention

Drugs

Ñ    Antibiotic prophylaxis before invasive procedures

Prognosis

Ñ    Significant operative mortality

Ñ    Long term survival compromised by increased risk of cardiac complications and death

 

 

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