Mitral valve replacement surgery involves the replacement of the diseased or damaged mitral valve with a new valve which could be either mechanical or obtained from human or animal tissue.
Q1. What is Mitral Valve and how does it function?
A1 The valve located between left upper chamber(Left atrium)and left lower chamber(Left ventricle) of the heart that ensures one way blood flow through the left atrium to the left ventricle. During ventricular relaxation, the mitral valve opens allowing the blood to flow through left atrium into the left ventricle. Blood fills the ventricle only to be emptied into the great artery or aorta during the contraction of the ventricle and this blood reaches the body tissues to oxygenate them.
During the ventricular contraction, the mitral valve closes preventing backflow of the blood into the upper left chamber or left atrium. This rhythmic opening and closure of the valve happens with each heart beat in a cardiac cycle.
Mitral valve has two flaps, also known as cusps or leaflets (in lay man’s terms, can be thought as doors) that are flexible and are attached to the papilary muscles located in the inner wall of the ventricle, through strong chord like tendons or fibrous strings referred to as Chordae tendinae. During left ventricular contraction (Systole), the papillary muscles contract and the strings like tendons of the papillary muscles attached to the cusps prevent prolapse or ballooning of these flaps into the left atrium (Mitral prolapse) when the mitral valve closes and prevent backflow of blood.
Q2. What is Mitral regurgitation?
A2 The following conditions lead to rupture of the strong fibrous strings called Chordae Tendinae that attach papillary muscles to the edge of the cusps and prevent bulging of the cusps into the left atrium during ventricular contraction(systole).
Mitral prolapse since a long time
Inflammation of the innermost tissue or membrane of the heart (Endocarditis)
Heart attack referred to as Myocardial Infarction in medical terms
However, once they rupture they no longer perform their function efficiently and lead to the development of the flail segment in the cusp of the mitral valve and make the valve floppy.This flail segment moves erratically into the left atrium during ventricle contraction. Mitral valve no longer closes appropriately thereby resulting in the backflow of the blood into the left atria and then pulmonary system(Pulmonary veins and lungs) rather than going into the aorta and then the rest of the body. This medical condition is referred to as Mitral Regurgitation. It remarkably affects the effciency of the heart and may lead to serious complications over time.
Q3 What are the causes of Mitral Regurgitation?
A3 There are several causes of the mitral regurgitation,such as:
Any condition that causes left ventricular dilatation(enlargement)-The heart is stretched in case of left ventricular dilatation and the cusps or the leaflets of the mitral valve can no longer meet appropriately in order to close the valve effectively.
Q4 What are the chief complaints(Sign and symptoms) of the patient in case of Mitral Regurgitation?
A4 Mitral Regurgitation could be Acute(sudden) or Chronic(Present since long). In Acute MR there is not time for compensation to ensue and it is usually caused by Papillary muscles or Chorda Tendinae rupture that may occur after heart attack(Post Myocardial Infarction). Under such circumstances the heart does not get time to adjust to the sudden pressure changes and leads to Acute Pulmonary Oedema. The patient may have heart failure. It is a medical emergency.
Chronic MR is characterized by compensatory mechanism of the heart in which the left ventricle becomes dilated over time(Dilated cardiomyopathy). It usually happens as a result of Coronary Artery Disease(CAD) in which the blood supply to the heart is compromised.
Under such circumstances the following chief complaints the patient may present with:
Q5. What is Mitral valve prolapse?
A5 Mitral valve prolapse is actually the mere bulging of the leaflets of the valve into the left atrium. Its cause is not known (idiopathic) or it may develop as a result of some connective tissue disease.
Q6 What are the symptoms of Mitral Valve prolapse?
A6 Most of the times, the patient does not have any symptoms and may be told by the physician who happens to auscultate his/her chest. Sometimes the patient may present with a specific group of symptoms which are referred to as "MVP Syndrome". The symptoms are:
Sign may include Midsystolic click, a cardinal sign to identify Mitral valve prolapse(found by your physician during chest auscultation with a stethescope). If the condition has advanced from mere Mitral prolapse to Valve dysfunction, this Mid systolic click may well be followed by the murmur related to Mitral regurgitation.
Q7 What may happen if I suffer from just Mitral valve prolapse?
A7 Mitral valve prolapse, although not dysfunctional at the moment,it cannot be considered completely normal either. It makes you vulnerable to the variety of risky medical conditions such as infection(Infective endocarditis). Bacteria may easily settle and establish control over the prolapsed valve. You are at increased risk of developing disorder of the heart beat rhythm(Arrhythmia) or it may eventually advance into Mitral regurgitation.
Q8 What are the treatment options in case of Mitral valve disease?
A8 Mitral valve either needs repair or must be replaced. The repair can be done through several procedures and various surgical approaches may be undertaken to reach the heart.The factors that are considered in order to determine the type of surgery and surgical approach are the general condition of the patient, his/her medical condtion and the actual condition of the valve.
Q9. What are various surgical approaches in Mitral valve surgery?
A9 Traditional heart surgery involves cutting through the middle of the breast bone or sternum to reach the heart. The incision is 6 to 8 inches long.There is another minimally invasive mitral valve surgery wherein the sternum is untouched. An incision is made on the right side of the chest between the ribs. The most advanced and least invasive technique currently being employed is Robotically assisted Mitral valve surgery.It involves few small(around 2 cm) key hole incisions between the ribs.
Q10 What are the advantages of Minimally invasive Mitral Valve surgery?
A10 Minimally invasive Mitral Valve surgery offers the following advantages over the traditional surgery done through the splitting of the breast bone:
Q11. How is traditional Mitral valve surgery carried out?
A11 A 6 to 8 inches long incision is made in the middle of the breast bone,known as Sternum and the ribcage is split open.The surgery is done under General Anesthesia which means the patient is put to sleep during the surgery. Medicines are given to stop the heart temporarily and is connected to the heart-lung bypass machine which takes over the function of the heart and lungs during the surgery, to maintain the oxygenation and circulation of the blood that has been rerouted to it. Now, the diseased valve will be repaired or replaced by the new valve. Once it is done, the heart is started again with the help of controlled electric shock and the sternum is joined back with wires. The skin incision is closed with stitches.
Q12. What are the different types of valve replacements?
A12. The new valve that has been put in place of the diseased or the damaged valve may be of the following two types:
Q13. What are the disadvantages of the mechanical valve?
A13 The disadvantages of the mechanical valve are:
Q14 What are the disadvantages of biological or tissue valves?
A14 The disadvantages of biological or tissue valves are:
Q15 Which is better,Valve repair or Valve replacement?
A15 Valve repair has always been the perfect choice provided it can be done safely and effectively and your surgeon also feels that the long term results and its success lies with the proposed option. However, if not possible, then the valve has to be replaced. The most common valve to be replaced is the Aortic valve followed by Mitral valve. Tricuspid or Pumponary valve are seldom replaced.
Dr Naresh Trehan
MBBS, Diplomat(American Board of Cardiac Surgery),Diplomat(ABS)
Chairman and Managing Director,Heart Institute, Division of Cardiothoracic and Vascular Surgery)
Medanta,The Medicity,Gurgaon, Delhi-NCR
Saket, New Delhi
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