Minimally invasive heart surgery refers to several approaches for bypassing blocked arteries. The minimally invasive procedures are less difficult and risky than conventional open heart surgery such as coronary artery bypass grafting (CABG).

The minimally invasive procedures restore healthy blood flow to the heart without having to stop the heart and put the patient on a heart-lung machine during surgery.

Currently, there are three types of these procedures:

• Minimally Invasive Direct Coronary Bypass (MIDCAB)
• Off-Pump Coronary Artery Bypass (OPCAB)
• Robotic Assisted Coronary Artery Bypass (RACAB)

Patients who have one of these procedures instead of open heart surgery have a lower risk of complications associated with the heart-lung machine, such as stroke, lung problems, kidney problems, and problems with mental clarity and memory. Other benefits are faster recovery and reduced hospital costs.

MINIMALLY INVASIVE DIRECT CORONARY BYPASS (MIDCAB)

This procedure is for patients with a blockage or blockages in the arteries on the front of the heart. (The left anterior descending (LAD) artery and its branches.)

It allows the surgeon to perform bypass surgery without splitting the breastbone. A cut is still made on the patient's left chest to expose the heart. But unlike conventional open heart surgery, the cut is much smaller.

Muscles in the area are pushed apart. A small part of the front of the rib (costal cartilage) is removed. Then the surgeon temporarily closes off the artery that lies underneath and frees its lower end. An opening is made in the pericardium, the covering of the heart.

A device is attached to the heart to reduce its movement. Finally, the surgeon connects the artery below the blockage to the LAD artery or one of its branches. Once the other artery under the costal cartilage is reopened, blood flow bypasses the blockage and feeds the heart. A heart-lung machine is not required.

This procedure offers the benefits of conventional open heart surgery but with less traumatic injury. The recovery may be closer to that experienced by angioplasty patients. However, the procedure is limited to those patients who need just one or two bypasses.

OFF-PUMP CORONARY ARTERY BYPASS (OPCAB)

During this procedure, the surgeon must cut open the chest and split the breastbone. A heart-lung machine is not used, however.

An artery or vein is taken from one of the legs and used to make the bypass. Like the MIDCAB procedure, a device is used to restrict movement of parts of the heart so that the surgeon can operate on it while it is still beating. The surgeon can repair four to five vessels on the beating heart during the same procedure.

The use of OPCAB has grown significantly because of its advantages over other procedures. Compared with patients undergoing conventional heart bypass surgery, those undergoing OPCAB:

• Have a shorter stay in the hospital after surgery
• May be able to return to normal activities more rapidly
• May have a decreased risk of stroke
• Require fewer blood transfusions

MIDCAB and OPCAB surgeries both take approximately 3 - 4 hours.

ROBOTIC ASSISTED CORONARY ARTERY BYPASS (RACAB)

RACAB is the latest advance in heart surgery. Surgeons use a robot to perform the bypass. The breastbone does not need to be split open at all.

Surgeons do not have direct contact with the patient. They perform the operation while watching a video screen. As the technology becomes more advanced, the surgeon may perform coronary artery bypass from a distant site (that is, from another room or another geographical location).

Due to the limited size of the MIDCAB cut, only certain patients are eligible for the procedure:

1. Patients who have a blockage in one or two coronary arteries on the front side of the heart, but are considered too high-risk for conventional bypass surgery or balloon angioplasty.

2. Patients who are otherwise healthy but have a blockage in one or two coronary arteries located on the front side of the heart.

In general, every patient with coronary artery disease is a candidate for OPCAB. However, it may be better to use the traditional CABG technique for:

• Those who have small coronary arteries and need several bypasses
• Those whose heart will not tolerate being worked on during the procedure
• Younger patients

Currently, the following patients with coronary artery disease are potential candidates for OPCAB:

1. Patients with poor heart function (very low ejection fraction).

2. Patients with severe lung disease (chronic obstructive pulmonary disease (COPD) and emphysema).

3. Patients with acute or chronic kidney disease.

4. Patients at high risk for stroke.

5. Patients with a calcified aorta.

Performing surgery on a beating heart (for both MIDCAB and OPCAB procedures) is technically more difficult than working on a heart that has been stopped with the help of the heart-lung machine. In addition, the stress on the heart during the procedure may lead to:

• Brain injury if blood flow to the brain is reduced for too long during surgery
• Irregular heartbeat
• Lower blood pressure
• More heart muscle damage

In some cases (usually less than 10%), it is necessary to switch to conventional CABG methods on an emergency basis.

MIDCAB and OPCAB patients typically spend one day in the surgical intensive care unit. Then they move to a regular surgery unit, where they receive cardiac rehabilitation.

The average hospital stay is 3 days for MIDCAB patients and 5-7 days for OPCAB patients. In contrast, a hospital stay of 6-10 days is typical for conventional CABG patients.

Patients who have had MIDCAB have lower chest wound infection rates than patients who have undergone CABG or OPCAB. A smaller incision means less exposure and handling of tissue, which reduces the chance of infection.

MIDCAB patients recover more quickly than those who undergo CABG or OPCAB. Within 2 weeks, most MIDCAB patients can return to their normal activity level, compared with 2-3 months for patients who have had conventional surgery.

OPCAB patients have a recovery similar to that of CABG patients. Most are able to return to full activity, including work, 2-3 months after the operation.

Aziz O, Rao C, Panesar SS, Jones C, Morris S, Darzi A, et al. Meta-analysis of minimally invasive internal thoracic artery bypass versus percutaneous revascularisation for isolated lesions of the left anterior descending artery. BMJ. 2007;334:617.