Minimally Invasive Valve Surgery: Incisions and Techniques

Minimally invasive valve surgery replaces or repairs the aortic, mitral or tricuspid valve through an incision of 2 to 5 cm, without dividing the whole breastbone. The heart-lung machine is connected through the groin vessels, ultrasound inside the oesophagus guides each step, and the valve work itself is identical to open surgery. Most patients have the breathing tube removed in theatre.

Valve disease accounts for 65% of the more than 550 minimally invasive operations performed by Dr. Udgeath Dhir, Principal Director Cardio Thoracic Vascular Surgery, Fortis Memorial Research Institute, Gurgaon, India. His principle is that the approach is customised: each valve, and each patient, gets the incision that suits the anatomy. This article sets out those incisions, how the heart is supported during surgery, how robotic surgery fits in, and how he operates on the tricuspid valve without stopping the heart. The complete guide to minimally invasive and robotic cardiac surgery covers patient selection, referral and cost.

Incisions for minimally invasive valve surgery: sternotomy to periareolar

Minimally invasive valve surgery uses five routes short of a full sternotomy: right anterior thoracotomy, inframammary or bikini, transaxillary, periareolar and robotic ports. For decades, valve surgery meant a median sternotomy: a long vertical incision down the centre of the chest, with the breastbone sawn through. Dr. Dhir traced the progression away from it as a steady reduction in incision size, each step keeping the operation inside the heart unchanged:

1. Median sternotomy: the classic midline incision, still used for about 60% of his operations.
2. Right anterior thoracotomy: an incision between the ribs on the right side of the chest.
3. Inframammary and bikini incisions: an incision hidden under the breast, paired with a small groin incision for the heart-lung machine. The name comes from the fact that nothing shows when the patient wears a bikini.
4. Transaxillary incision: about 5 cm in the armpit, now used at his unit to treat rheumatic double valve disease.
5. Periareolar incision: hardly 2 cm around the edge of the nipple.
6. Robotic ports: keyhole openings for the arms of a surgical robot.

The cosmetic driver is real. Many of his valve patients are young women with rheumatic heart disease, for whom a visible chest scar has social consequences. After an armpit operation, he observed, nobody can tell the patient has had heart surgery unless a mechanical valve gives an audible click.

How the heart-lung machine is connected through the groin

Dr. Dhir's unit connects the heart-lung machine (cardiopulmonary bypass) away from the chest, through peripheral cannulation. Two long tubes (cannulas) are inserted through the groin: one into the femoral artery, which returns oxygenated blood to the body, and one into the femoral vein, threaded up to the inferior vena cava (the large vein that carries blood from the lower body to the heart) to drain blood to the machine.

Through additional small openings, the team then clamps the aorta, delivers the solution that stops the heart, and vents the heart to keep the field free of blood. Every step is guided by transoesophageal echocardiography (TEE), an ultrasound probe passed into the oesophagus that gives a live view of the heart from directly behind it. Before a mitral repair begins, his team uses the same probe in the anaesthetised patient to assess the valve and confirm it is suitable for repair.

Peripheral cannulation is not always possible. For aortic valve replacement, when the case is complex, when peripheral vascular disease rules out cannulation through the groin, or when the patient is very obese, Dr. Dhir uses an upper hemisternotomy instead.

Minimally invasive aortic valve replacement through the second rib space

About 90% of Dr. Dhir's aortic valve replacements (AVR) are done through the second intercostal space on the right side, without cutting any bone. The second intercostal space is the gap between the second and third ribs. The only alternative he uses is an upper hemisternotomy, a 5 cm incision that divides only the top of the breastbone, reserved for the indications above.

Through this opening the team removes the diseased valve and sews in the new one with long instruments. At the end of the operation, the only visible signs are the small incision high on the right side of the chest and a temporary pacing wire. The breastbone is left intact, which spares the patient the period of bone healing that a full sternotomy requires.

Minimally invasive mitral valve repair through a 2 cm incision

A prolapsing, leaking mitral valve can be repaired through a periareolar incision of about 2 cm, the smallest incision Dr. Dhir's unit now uses for valve work. The mitral valve sits on the left side of the heart, between the left atrium and the left ventricle. When its leaflets bulge back into the atrium (mitral valve prolapse), the valve leaks, a condition called mitral regurgitation. Severe regurgitation strains the heart and often needs surgery; where possible, a repair that preserves the patient's own valve is preferred.

Dr. Dhir showed a recent example. A man with a classic prolapsing mitral valve causing severe regurgitation, and an atrial septal defect (a hole between the upper chambers of the heart), had both corrected through a periareolar incision of about 2 cm. Long instruments were passed through it, the valve was repaired and the hole closed, and he was discharged on day three with little pain and no visible sign of surgery.

Technology has removed one of the slowest steps. Fixing a valve in place requires many sutures, each tied with several knots, which is laborious through a small opening. His unit now uses an automated knot-fastening device: instead of tying five knots, a single click secures each suture. "It makes my life very easy in valve surgery," he said.

Transaxillary double valve replacement through the armpit

Patients with rheumatic disease of both the mitral and aortic valves (double valve disease) can have both valves treated through a 5 cm skin incision in the armpit. This transaxillary approach is a recent advance in Dr. Dhir's practice. The opening inside the chest is barely large enough to pass a prosthetic valve through, which is why the approach depends on specialised retractors and long instruments.

One patient he described, an elderly person who needed two valves replaced, received bioprosthetic valves through this route. Bioprosthetic (tissue) valves are made from animal tissue and generally do not require lifelong blood thinners, which is why they are commonly chosen for older patients. Dr. Dhir noted that earlier tissue valves rarely lasted more than ten years, whereas he put the expected lifespan of current valves at 15 to 20 years, with his own results so far showing them functioning well at up to eight years. The trade-off between tissue and mechanical valves is examined in Dr. Z S Meharwal's guide to choosing between a mechanical and tissue heart valve.

Tricuspid valve surgery on a beating heart

Dr. Dhir operates on the tricuspid valve through a 3 to 4 cm chest incision without stopping the heart, including in patients who have already had mitral or double valve replacement. The tricuspid valve, between the right atrium and right ventricle, has long been the neglected valve. It causes particular problems in these patients when they later develop tricuspid regurgitation. Blood leaking backwards through the valve congests the liver and the abdomen, producing an enlarged, congested liver, fluid in the abdomen (ascites) and swelling of the legs.

These are difficult patients. Some have had two previous sternotomies, which makes a redo operation complex. For these redo operations he uses peripheral cannulation and keeps the heart beating throughout.

How the heart keeps beating during valve replacement

A doctor from Nigeria asked how the heart can keep beating while a valve is being replaced. Dr. Dhir explained the mechanism step by step:

1. The patient is placed on cardiopulmonary bypass through peripheral cannulas, with arterial blood returned to the aorta.
2. The superior and inferior venae cavae, the two great veins entering the right atrium, are snugged around the venous cannulas. All blood from the upper and lower body therefore drains to the machine, leaving the right side of the heart empty.
3. A roller pump in the machine perfuses the body through the aorta, and the heart keeps beating.
4. The body is cooled to about 30°C, monitored by a temperature probe, so the heart beats slowly.
5. The surgeon opens the right atrium and sews in the new tricuspid valve while the heart continues to beat.

Because the operation is on the right side and the left side of the heart is never opened, the risk of air entering the circulation to the brain (air embolism) is low, provided there is no hole between the upper chambers through which air could cross; transoesophageal echocardiography checks for one beforehand. The beating heart is, in his words, what the heart is made for. At times the heart has to be stopped, for aortic and mitral valve surgery, heart transplantation and acute aortic dissection. In certain situations, however, stopping the heart can be harmful, and the heart may not recover enough to come off the machine. Those are the patients he operates on while the heart beats, and he reports very good results. After surgery, the congestion, ascites and leg swelling of tricuspid regurgitation settle and the patient becomes comfortable.

Robotic mitral valve surgery and ASD closure

In robotic valve surgery the valve is repaired or replaced exactly as in conventional surgery; only the approach changes, with the surgeon controlling robotic arms from a console. Robotic cardiac surgery takes the minimally invasive principle one step further. Ports are placed between the ribs, much as in laparoscopic abdominal surgery, and the robot's arms are docked to them. Dr. Dhir sits at a console and controls the arms, with his surgical assistant and anaesthetist in theatre and a perfusionist running the heart-lung machine.

In response to the same attendee, he explained that a valve is replaced robotically in the same way as in conventional surgery. The cross-clamp, cautery, scissors, needle holders and sutures are the same; the robotic arms simply carry the long instruments he would otherwise hold. "Nothing changes except the approach." The difference is control: four arms instead of two hands and an assistant, with the ability to switch from one arm to another. His unit uses the robot for mitral valve repair and replacement and for atrial septal defect closure.

Pain control and recovery

Small incisions only pay off if the patient recovers quickly, and Dr. Dhir's team plans for that from the start. Most patients are extubated on the operating table, meaning the breathing tube comes out before they leave theatre. A thoracic epidural, a fine catheter placed near the spinal nerves that supply the chest, delivers continuous pain relief for the first 24 hours, much as other specialties such as orthopaedics use it. The patient is pain-free and can breathe normally. His summary of the result: less pain, less trauma, early walking, and no visible evidence of surgery.

When the small incision is not the answer

The valve surgery described here is a choice, not a default. Dr. Dhir still performs 60% of his operations through a conventional sternotomy, and he regards conversion to a full sternotomy during a minimally invasive case as sound judgement rather than failure. The checklist that decides which route a patient receives, along with when to refer a patient with valve symptoms, is set out in the complete guide. Coronary surgery through the left chest is covered in the article on minimally invasive coronary bypass and endarterectomy.

For cost ranges, see the treatment-cost pages for aortic valve replacement, tricuspid valve repair and replacement and atrial septal defect closure. The attendee questions on beating-heart and robotic valve surgery, with Dr. Dhir's full answers, are on the Live Discussion page. For a catheter-based alternative in older patients with aortic stenosis, see Dr. Subhash Chandra's guide to TAVI, and for another surgeon's experience of robot-assisted heart surgery, Dr. Yugal Kishore Mishra's guide to robotic cardiac surgery.