Valvular heart disease
Description
Valvular heart disease occurs when the heart valve no longer closes properly (valvular insufficiency) or becomes too tight (valvular stenosis). Depending on the severity of the valvular defect, cardiac insufficiency will develop either gradually or acutely along with corresponding symptoms. Aside from that basic distinction, the following categories of valvular heart disease can be distinguished: valve stenoses (aortic stenosis, mitral stenosis, pulmonary stenosis, tricuspid valve stenosis) and valve insufficiencies (aortic insufficiency, mitral insufficiency, pulmonary insufficiency, tricuspid insufficiency).
Symptoms
The symptoms and the degree of performance impairment caused by the valvular defect can be divided as per the NYHA (New York Heart Association) into four functional levels I-IV. Light to moderate valvular heart disease often causes no symptoms.
The classic valvular heart disease symptoms re reduced performance appear at first only with bodily exertion. These are primarily: shortness of breath (dyspnea), accelerated pulse, often irregular pulse rate (arrhythmia), rapid fatigue and occasional dizziness. If the aortic and/or mitral valves on the left side of the heart are affected (left-sided heart failure), the main symptom is shortness of breath. This is due to the backflow of blood into the lung.
In higher order aortic stenosis, symptoms such as angina, dizziness and fainting may occur in addition to shortness of breath. If the tricuspid and/or pulmonary valves on the right side of the heart are affected (right-sided heart failure), the main symptoms than can develop are fluid accumulation in the abdomen (ascites) and swelling (edema) of the ankles and lower legs.
Causes and Risks
The major causes of acquired valvular heart disease are: rheumatic fever (favors the mitral and aortic valves), degenerative changes to valve components (e.g. calcification, mitral valve prolapse, Marfan syndrome), infections (e.g. endocarditis and/or myocarditis) and underlying cardiac diseases (condition after myocardial infarction, distended valves from pulmonary hypertension).
Examination and Diagnosis
To determine the severity of the disease an echocardiogram is often performed, or in special cases a cardiac MRI or cardiac catheterization, in addition to the clinical examination. An even more accurate picture of valve morphology and related medical problems is possible with a transesophageal echocardiography ("sip echo"). In this, an ultrasound examination of the heart occurs via a thin, flexible tube pushed through the esophagus and close to the heart. Newer technologies such as 3D echocardiography and 3D color Doppler sonography may be considered, especially before surgery. A resting ECG is routinely used in evaluation of vascular heart disease, and a long-term ECG may provide important information about heart rhythm.
Treatment
Valvular heart disease is basically a mechanical problem and cannot be improved or reversed by drug therapy. (Only in case of acute bacterial inflammation of a heart valve - infective endocarditis - may high-dose antibiotic therapy prevent the development of valvular heart disease).
However, drugs can relieve the symptoms of valvular heart disease. For shortness of breath (dyspnea), diuretics are used. For decreasing pump performance and enlargement of the heart chambers, ACE inhibitors, AT1 antagonists and beta blockers will be considered. For slowing the heart rate in atrial fibrillation, beta blockers or verapamil and often also digitalis are used. For atrial fibrillation, an anticoagulant to prevent blood clot formation with vitamin K antagonists is also necessary - this is called a thromboprophylaxis.
In the surgical correction of valvular heart disease one must distinguish between valve-preserving procedures (valve repair) and heart valve replacement:
Valve-preserving surgery is now aimed primarily at mitral valve defects. For treatment of severe mitral insufficiency a new, non-surgical technique has been developed and approved for clinical applications: percutaneous endovascular reconstruction of the mitral valve by inserting a mitral clip. This method is recommended for high-risk patients and those with severe cardiac insufficiency.
For heart valve replacement one can choose between mechanical and biological heart valves.
An recent alternative to open heart surgery is the use of aortic valvular prostheses in cardiac catheterization procedures (transcatheter aortic valve implantation: TAVI). In this method, the new heart valve is sewed into a stent (small mesh frame). In a folded state it is brought into position in the defective aortic valve using a catheter (thin tube) either via a femoral artery or surgically through the apex of the heart.
Course and Prognosis
The prognosis in valvular heart disease depends primarily on which heart valve is affected and whether the defect has already damaged the heart muscle.
If a major valvular heart defect is untreated, it leads over time to a weak heart and can ultimately be fatal. Mild valvular heart disease does not usually require surgery and may be barely noticeable.
Miscellaneous/ Other Comments
The prime consideration with a mechanical heart valve is the careful monitoring of anticoagulation and taking of anticoagulant medication in timely doses as determined by the doctor. Both mechanical and biological prosthetic heart valves are more prone to bacterial infection than native valves, particularly when bacteria are increasingly being washed into the blood. Therefore it is necessary that patients with mechanical or biological heart valve prostheses or heart valve reconstruction using alloprothetic material, are treated consistently with antibiotics for bacterial infections (e.g. purulent bronchitis, purulent sinus infection, urinary tract infection).