What is balloon mitral valvotomy (BMV/PTMC)?

What is balloon mitral valvotomy (BMV/PTMC)?

Balloon mitral valvotomy is known in short as BMV. BMV is enlargement of a narrowed mitral valve using high pressure balloons attached to the tip of tubes known as balloon catheters. The procedure is also known as percutaneous transmitral commissurotomy or PTMC. It means that mitral valve is split using devices introduced through the skin across the mitral valve. Earlier it was closed mitral valvotomy or open mitral valvotomy which were surgical procedures. Latter was an open heart surgery. Both procedures needed opening up of the chest and general anaesthesia while BMV/PTMC is done under local anaesthesia using guidance from continuous X-ray imaging.

Mitral valve is the valve between the left upper and lower chambers of the heart. Common cause of narrowing of mitral valve in developing countries is rheumatic fever, a disease which affects the joints and heart valves. Narrowing of mitral valve is known by the medical term mitral stenosis. Persons with mitral stenosis have breathlessness, initially on exertion and later on during sleep and at rest. When severe mitral stenosis becomes symptomatic, it needs to be opened up either by surgery or BMV/PTMC. Decision on which procedure is suitable for the person depends mainly on the results of a test known as echocardiography or ultrasound imaging of the heart.

Two main factors considered while deciding whether the mitral valve narrowing is suitable for BMV/PTMC or open surgery is whether the valve has leak in addition to narrowing and if the valve is calcified or not. If there is significant leak in addition to narrowing, it is not considered for BMV/PTMC. But those with minor leaks may still be considered, with the option of open surgery in case the leak worsens. Those with significant calcium deposits in the mitral valve are unlikely to get good results with BMV/PTMC. Moreover, there is a higher risk of severe damage to the valve in such cases which can sometimes produce severe leaks while attempting to enlarge using balloon inflation. Such cases are also better treated by open surgery.

BMV/PTMC being a key-hole procedure, the person can walk about the next day and possibly go home from the hospital in a day or two. This is in case of an uncomplicated procedure. Those unfortunate few who develop severe leaks of mitral valve may have to undergo open surgery to replace the damaged valve with an artificial valve. But these are very rare situations with meticulous selection of cases by echocardiography. Other occasional problems are bleeds from the puncture sites or anywhere else which may need extra treatment or procedure to cure. Sometimes clots from the heart can get dislodged during the procedure and move out into the blood stream. These can cause problems by blocking blood vessels elsewhere and need further treatment. Detailed echocardiographic studies before the procedure to detect clots within the heart can avoid this problem to a great extent.

BMV/PTMC balloon is introduced through the femoral vein under local anaesthesia and guided to the heart under continuous X-ray imaging. Occasionally it has been done under ultrasound guidance in pregnant women, though most often it is easier to do with lead shield screening of the tummy to avoid radiation to the baby in the womb. Femoral vein is the blood vessel which returns deoxygenated blood from the legs to the heart. For the balloon to pass from the right upper chamber of the heart to the left upper chamber of the heart, a puncture using a special long needle is needed in the wall between the two chambers. Balloon catheter is introduced through tubes placed across this hole.

After reaching the left upper chamber, deflated balloon is guided across the narrowed mitral valve. Once the correct position across the mitral valve is confirmed, the balloon is inflated with a syringe attached to the other end, outside the body. Enlargement of the balloon is closely monitored on the X-ray imaging screen. Once the valve orifice has been enlarged, the balloon is deflated and brought back to the upper chamber. Result is usually checked immediately by bedside echocardiogram if feasible, or else fall in pressure gradient across the valve also confirms the success of the procedure. Devices are removed from the heart and compression followed by bandaging done in the groin, to close off the hole in the femoral vein.