Minimally invasive heart surgery – a look through the keyhole

The human heart is often described as a motor that quietly and unobtrusively drives body and mind. The high-performance motor heart beats around three billion times in the course of a lifetime and pumps around 18 million liters of blood through the body. This precision machine is usually only noticed when it stumbles. Heart attacks ,  cardiac arrhythmia  and narrowing of the coronary arteries make heart diseases the  number one cause of death  in Germany.

Technical progress makes “buttonhole surgery” possible

Minimally invasive surgery, also known as “keyhole surgery” or “buttonhole surgery”, is one of the enormous medical advances in the treatment of heart disease in recent decades.

This technique is used in heart surgery in most heart centers in Germany.

Bypass surgery: minimally invasive heart surgery

Around 80 percent of all minimally invasive heart procedures are bypass operations, which help to restore the oxygen supply to the heart.

With this technique, the surgeon dispenses with the wide opening of body cavities. Instead, he operates with a so-called endoscope and extremely small instruments through mini incisions – like through a keyhole.

The  endoscope  is a tube-like instrument that uses an optical system to make images from inside the body visible to the doctor. 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 the patient than conventional methods: In a conventional  bypass operation  , the sternum has to be severed. It then takes up to eight weeks for this artificially induced  fracture  to heal – including pain and restricted mobility.

Lower load but higher monitoring effort

Minimally invasive procedures are less stressful for the patient than conventional heart operations. They recover faster, spend less time in the intensive care unit and can leave the hospital sooner. For anesthesiologists and cardiac surgeons, however, such interventions pose a much greater challenge, because the monitoring of the circulatory system during the intervention on the beating heart must be particularly close.

In a conventional bypass operation, the heart is connected to a heart-lung machine and the heart itself “shuts down”. Although this technology is mature and can take over the function of the heart and lungs for a limited time, the overall burden on the body is very high. The aim of minimally invasive heart surgery is therefore not only a small wound area, but also the elimination of the heart-lung machine.

During manipulation of the beating heart, the circulation must be monitored as closely and precisely as possible. The latest developments in the combination of medicine and electronics have led to intelligent monitoring methods that further reduce the risk and stress of cardiac surgery.

MIDCAB – the direct route to the coronary arteries

With a minimally invasive surgical intervention on the coronary arteries (MIDCAB = minimally invasive direct coronary artery bypass), one or two, sometimes even three narrowed coronary arteries can be supplied with blood again by connecting them to a healthy artery.

This is how the procedure works:

• A 3 to 4 cm incision is made over the heart in the 4th intercostal space.
• Now, under direct vision or after an endoscope (metal fiber optic cable) with a camera has been inserted, the left internal thoracic artery is located and exposed.
• The pericardium is opened and the anterior vascular branch, which is very often constricted, is exposed.
• A stabilizer makes it possible to immobilize the operating area in the area of ​​the vascular connection.
• The blocked vessel is tied with a noose and tied for a short time after a drug is injected to keep the blood fluid. Up to 20 minutes of such a vascular rupture are usually well tolerated by the heart muscle without any signs of oxygen deficiency.
• The surgeon then connects the narrowed, tied off coronary artery to the internal thoracic artery.
• All vascular ligatures are then released again.
• A wound drainage drains the wound secretion that forms in the chest to the outside.

Good results achieved with MIDCAB

So far, very good results have been achieved with this procedure: 96 to 98 percent of the new vascular connections are still patent even after 1 year, and multiple bypasses are also possible with the MIDCAB technique. Since the MIDCAB operation has only existed for a few years, there are hardly any longer observation periods.

For comparison: With a conventional bypass, up to 90 percent of the new vascular connections are still open after 15 years – at least if an artery was used as a donor vessel.

Surgeon and robot as a well-rehearsed team

In 1998, Professor Friedrich Wilhelm Mohr from the Leipzig Heart Center was the first surgeon in the world to perform a heart operation without standing directly at the treatment table. He directed surgical instruments and a tiny camera, which were inserted into the body “through the keyhole” via incisions of eight to ten millimeters, from a control panel several meters away.

For several years, the surgical robot “Da Vinci” has conquered the operating theaters of heart surgeons. The heart surgeons use the robot to operate on the beating heart, place bypasses, replace  heart valves  and repair defective cardiac septa. In general surgery, the robot is only gradually being used. The “Da Vincis” are now in numerous university clinics and other large clinics, where they are used, among other things, for urological interventions.

How does “Da Vinci” work?

The “Da Vinci” robot system consists of two main components: the control console and the robot arms. The surgeon sits at the console and uses two joysticks to steer the electronic robotic arms on which the (interchangeable) surgical instruments are located. He has a high-resolution 3D video image in front of him that shows the surgical field magnified 20 to 30 times.

The surgeon’s hands rest beneath the monitor and use the instruments with the same flexibility as in open surgery. Even better: the translation of the movements from the console to the instruments is jitter-free and can be adjusted individually. For example, if the surgeon turns his hand ten centimeters, the instruments only move one centimeter. In this way, the surgeon can work much more precisely and attach even the finest sutures without complications.

However, the robot does not make the surgeon superfluous. Quite the opposite: he sits at a distance from the patient, but never lets the system take control. The robot supports the surgeon and helps him to be more precise.

… and man remains man

Great hopes are currently pinned on minimally invasive procedures, even if the costs for a surgical robot are high. On the other hand, developments from the border areas of medicine, biology and electronics ensure ever better control and monitoring methods, which also make complicated interventions easier and more controllable.

However, the human risk factor remains uncontrollable: poor 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.