Dr Carl Shakespeare consultant cardiologist  
       
 
   
consultant cardiologist
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Conducting System

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arrowValvular Abnormalitities and
Murmurs of the Heart

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Valvular Abnormalities and Murmurs of the Heart:

There are four heart valves that allow blood to be pumped in one direction through the heart, and prevent any backflow. Any narrowing of a valve would restrict flow through the heart and result in a pressure build up behind the valve. Any leakage (regurgitation) of a valve results in the increased heart filling with blood and increasing volume of various chambers of the heart.  Narrowings or leakages of the valves can cause symptoms and are detected by listening to the heart for murmurs which reflects turbulence of blood flow around the defective valve.

With any valvular condition, exposure to blood borne infection can be detrimental. Blood infections tend to target narrow or leaky valves in particular and can result in rapid destruction and clinical deterioration (see Endocarditis). The mouth is considered the dirtiest part of the human body, and is the commonest cause of a blood borne infection that can attack valves. For this reason, with significant valvular disease, good dental hygiene with six monthly visits to the dentist are recommended. On each visit, patients are usually given antibiotics prior to dental work.

Tricuspid Valve:
This allows blood to pass from the right atrium to the right ventricle. Any narrowing of this valve would restrict flow, but this is uncommon. Leakage of this valve is called Tricuspid Regurgitation and is quite common. It can occur secondarily to pressure or volume increases further along in the lung circulation or the left heart. Occasionally it can occur due to an infection (endocarditis) attacking the valve. The clinical effects of tricuspid regurgitation vary. Some patients may be asymptomatic. If the leakage is more severe, then back flow into the veins feeding into the heart will occur, and cause swelling in the legs and enlargement of the liver. The valve can be repaired surgically.

 

Pulmonary Valve:
This regulates flow from the right ventricle to the lung circulation (pulmonary arteries). Narrowing of this valve (Pulmonary Stenosis) is uncommon and is usually detected in childhood as a murmur. It can be treated with a balloon stretching device to open the valve. Leakage of the valve (Pulmonary Regurgitation) is more common, but usually reflects pressure or volume increases further on in either the lung circulation or the left side of the heart.

Mitral Valve:
Abnormalities affecting this valve which regulates flow between the left atrium and the left ventricle are quite extensive and briefly described below!

mitral stenosisMitral Stenosis:
This occurs when the valve becomes thickened and stuck together. It is much less common nowadays and mostly seen in immigrant groups from Asia and Africa. In the UK residual cases are sometimes seen in the elderly population. Most commonly it was attributed to childhood exposure to rheumatic fever, which resulted in “gumming up” of the valve over subsequent decades. Clinical effects may vary according to severity, but back pressure into the lungs causes breathlessness, and swelling in the legs. Stretching of the atrium can also occur causing palpitations and arrhythmia. Treatment of mitral stenosis is based on treating the arrhythmias that can co exist and preventing the risk of stroke. For more significant stenosis, either a balloon stretching operation (mitral valvuloplasty) which can be done without opening the chest, or by replacing the valve by open heart surgery.

Mitral Regurgitation:
This is quite a common condition and can occur due many causes. The valve may be naturally floppy and begin to leak over time (so called “Floppy Mitral Valve”). Or the valve can “prolapse” back on its hinge causing an imperfect seal, causing a progressive leak. Occasionally the valve may leak due the hinge support (so called mitral annulus) becoming stretched because of enlargement of the left ventricle. Sometimes the valve can leak because of damage to the valve supports due to a heart attack. Alternatively, the valve can become damaged by blood borne infection (so called endocarditis).
mitral regurgitation
Clinical presentation: Patients are frequently asymptomatic at the time of diagnosis. Over a period of time mitral regurgitation is associated with progressive heart enlargement and breathlessness.

Investigation of mitral regurgitation: Echocardiography is the mainstay of investigation, often supplemented by more invasive echocardiography (transoesophageal echocardiography). Other tests may be performed to determine the mechanism, such as coronary angiography.

Treatment of mitral regurgitation: Treatment these days is focussed at an earlier stage, preferably before the patient becomes breathless or the heart enlarges. Although medication may help with breathlessness, surgical treatment either by repairing the valve or replacing it is the more definitive treatment.

Aortic Stenosis: The aortic valve is the last valve in the heart and regulates flow from the left ventricle into the aorta. Narrowing of this valve is not uncommon. Previously, in previous generations it was mainly due to rheumatic fever in childhood causing progressive “gumming up” of the valve leaflets, eventually restricting flow. Rheumatic fever is now less common, and stenosis is more likely to be due to a defective valve with two cusps instead of three (so called bicuspid valve). More recently, there is a view that progressive gumming up can occur due to deposition of cholesterol between the leaflets.

Clinical presentation of aortic stenosis:
Although it can be an incidental finding, presentation in younger patients may include dizziness on exertion, collapse, or chest pain. In older patients, breathlessness is a more common symptom.

Investigation and treatment of aortic stenosis: Echocardiographic assessment is the main investigation. Despite the severity of the narrowing determined by echocardiography, it is the development of any of the above symptoms that determines when the aortic valve needs surgical replacement. Indeed, surgical replacement of the valve is the definitive treatment for severe narrowing. However, patients frequently do not require surgery for many years, and just require echocardiographic assessment periodically. More recently, medical replacement of the valve without open heart surgery is becoming an option. However, it is early days yet in any long term evaluation of the procedure.

Aortic Regurgitation:
This is when the last valve before blood is pumped from the left ventricle into the aorta starts to leak. A variety of causes exist, but it usually occurs as a result of the aorta dilating due to weakness in the wall of the vessel. If the valve becomes stretched or damaged from infection (endocarditis), the valve can leak. For asymptomatic patients, the valve and aorta are monitored over a period of time.

Clinical Presentation and Treatment of aortic regurgitation: In asymptomatic patients, if the heart or aorta enlarges on echocardiography, or the leak of the valve progresses, then surgical replacement is indicated. If patients develop breathlessness, then surgical replacement of the valve becomes necessary.

Cardiac risk factors

  • Smoking
  • Hypertension
  • Cholesterol
  • Diabetes
  • Family history/other generic factors
  • Miscellaneous causes