Minimally Invasive Cardiac Surgery: the View Through the Keyhole

The human heart is often described as an engine that quietly and unobtrusively drives the body and mind. Yet the heart, a high-performance engine, beats about three billion times in the course of a lifetime and pumps about 18 million liters of blood through the body. This precision machine is usually only noticed when it starts to stumble. Heart attacks, cardiac arrhythmias and narrowing of coronary arteries continue to make diseases of the heart the No. 1 cause of death in Germany.

Technological advances enable “buttonhole surgery”

Among the enormous medical advances made in recent decades in the treatment of heart disease is minimally invasive surgery, also called “keyhole surgery” or “buttonhole surgery. This technique is used for cardiac surgery in the majority of heart centers in Germany.

Bypass surgery: minimally invasive heart procedures.

About 80 percent of all minimally invasive heart procedures are bypass operations, which are used to restore oxygen supply to the heart. With this technique, the surgeon does not open body cavities wide. Instead, he operates with a so-called endoscope and extremely reduced instruments through mini-incisions – like through a keyhole. The endoscope is a tube-shaped or tubular instrument that uses an optical system to make images from inside the body visible to the doctor outside. In addition, a small camera can transmit the images to a monitor. Especially in the field of heart surgery, this technique is much more comfortable for patients than conventional methods: In conventional bypass surgery, the sternum must be cut. It then takes up to eight weeks for this artificially induced bone fracture to heal – pain and restricted movement included.

Less stress but more monitoring required

For patients, minimally invasive procedures are less stressful than conventional heart surgery. They recover more quickly, spend less time in the intensive care unit, and can leave the hospital sooner. For the anesthesiologist and cardiac surgeon, however, such interventions pose a significantly greater challenge because the monitoring of the circulation must be particularly close during the procedure on the beating heart. In conventional bypass surgery, the heart is connected to a heart-lung machine and the heart itself is “immobilized.” While this technique is mature and can take over the function of the heart and lungs for a limited period of time, the overall burden on the body is very great. Therefore, the goal of minimally invasive cardiac surgery is not only to minimize the wound area, but also to eliminate the need for a heart-lung machine. During manipulation of the beating heart, the circulation must be monitored as closely as possible. In this regard, the latest developments from the combination of medicine and electronics have led to intelligent monitoring methods that further reduce the risk and burden of cardiac surgery.

MIDCAB – the direct route to the coronary arteries.

A minimally invasive surgical procedure on the coronary arteries (MIDCAB= Minimally Invasive Direct Coronary Artery Bypass) allows one or two, sometimes three, narrowed coronary arteries to be reperfused by connecting them to a healthy artery. Here’s how the procedure works:

  • A 3 to 4 cm incision is made above the heart in the 4th intercostal space.
  • Now, under direct vision or after an endoscope (metal light guide) with camera is inserted, the left internal mammary artery is visited and exposed.
  • The pericardium is opened and the very often narrowed anterior vascular branch is visualized.
  • A stabilizer allows the surgical area to be immobilized in the area of the vascular connection.
  • The occluded vessel is encircled with a sling and tied shut for a short period of time after a drug is injected to keep the blood fluid. Up to 20 minutes of such vascular interruption is usually well tolerated by the heart muscle without signs of oxygen deprivation.
  • Then the surgeon connects the narrowed ligated coronary vessel to the internal mammary artery.
  • Afterwards, all the vascular ligatures are released.
  • A wound drain drains the wound secretions that form in the chest to the outside.

Good results achieved with MIDCAB

Very good results have been obtained so far with this procedure: 96 to 98 percent of new vascular connections are still open after 1 year, and multiple bypasses are also possible with the MIDCAB technique. However, since MIDCAB surgery has only been around for a few years, there are hardly any longer observation periods. By comparison, with conventional bypass, up to 90% of new vessel connections are still open after 15 years-at least if an artery was used as the donor vessel.

Surgeon and robot as a well-rehearsed team

In 1998, Professor Friedrich Wilhelm Mohr of the Heart Center Leipzig was the world’s first surgeon to perform heart surgery without standing directly at the treatment table. He directed surgical instruments and a tiny camera, which were inserted “through the keyhole” into the body via incisions of eight to ten millimeters, from a control panel several meters away. For several years now, the “Da Vinci” surgical robot has been conquering the operating rooms of heart surgeons. Cardiac surgeons use the robot to operate on the beating heart, place bypasses, replace heart valves and repair defective cardiac septums. In general surgery, the robot is only gradually being used. The “Da Vincis” are now in numerous university hospitals and other large clinics, where they are used for urological procedures, among other things.

How does “Da Vinci” work?

The “Da Vinci” robotic system consists of two main components: the control console and the robotic arms. The surgeon sits at the console and uses two joysticks to steer the electronic robotic arms, which hold the (interchangeable) surgical instruments. In front of him is a high-resolution 3-D video image showing the surgical field magnified 20 to 30 times. The surgeon’s hands rest below the monitor and use the instruments with the same flexibility as in open surgery. Even better, the translation of movements from the console to the instruments is jitter-free and can be adjusted individually. For example, if the surgeon rotates his hand ten centimeters, the instruments move only one centimeter. In this way, the surgeon can work much more precisely and apply even the finest sutures without complications. However, the robot does not make the surgeon superfluous. On the contrary, although the surgeon sits at a distance from the patient, he never leaves control to the system. The robot supports the surgeon and helps him achieve greater precision.

… and the human remains human

Great hopes are currently resting on minimally invasive surgery, even if the cost of a surgical robot is high. On the other hand, developments from the frontiers of medicine, biology and electronics are providing ever better control and monitoring methods that make even complicated interventions simpler and more controllable. However, the human risk factor remains uncontrollable: incorrect diet, smoking, alcohol, stress and lack of exercise are still the main causes of heart disease – regardless of how well the consequences can be ironed out later.