Invasive therapy
Invasive therapeutic options for revascularization in coronary heart disease (CHD) include catheter intervention with vasodilatation or bypass surgery. Both methods aim to restore the patency of the narrowed or blocked coronary artery (revascularization).
Heart catheter
Percutaneous transluminal coronary angioplasty (PTCA) can be used as a standard method, i.e. as the sole balloon dilatation of the vessel (balloon dilatation), or in combination with a stent graft to keep the vessel open mechanically. This form of therapy is used when there is a one to three vessel disease with significant vasoconstriction of more than 70% and the patient suffers from stable or unstable angina pectoris. The aim of this procedure is to restore the blood flow in the coronary arteries.
A successful vasodilatation with subsequent freedom from symptoms occurs in about 90% of cases. Approximately 30% of the patients show a renewed narrowing of the coronary vessel with pectanginous symptoms (chest constriction) after 6 months; if a stent was implanted during PTCA, this value drops to approximately 15-20%. In stent implantation, a grid-like tube is inserted into the narrowed area of the coronary vessel after dilation to keep it permanently open.Most patients with residual vasoconstriction can receive PTCA to reopen the vessel without increased risk.
The procedure has the following possible complications: Manipulation of the vessels with catheter wire can lead to dissection, i.e. injury to the vessel wall with subsequent bleeding between the vessel wall layers. If this occurs, a stent is inserted to close the detachment of the vessel wall layers. If this is unsuccessful, emergency bypass surgery must be performed. The PTCA procedure has a mortality rate of 1%. If the main stem of the left coronary artery is affected by a narrowing (stenosis), no catheter intervention is performed, but a bypass operation is performed.
Bypass operation
Bypass surgery is the recognized surgical procedure for reopening occluded coronaries and is also known as coronary artery bypass graft (CABG). Bypass surgery is performed when there is a main stem narrowing of the left coronary artery, a symptomatic three-vessel disease with various narrowing sites, or a two-vessel disease with narrowing near the stem that causes symptoms. Narrows that are close to the trunk of the vessel are unfavorable for blood flow and carry the risk of making one (in the case of the right coronary artery) or two important (in the case of the left coronary artery) supplying vessels impermeable.
Furthermore, the indication for surgery is given if angina pectoris could not be successfully treated by drug therapy or catheter intervention. The requirements for surgery are: During the operation, the chest is opened and the heart is stopped using the heart-lung machine, so that it no longer pumps itself, but the circulatory function is ensured by extracorporeal circulation (taking place outside the body) via the machine. The narrowing of the coronary arteries (coronary stenosis) is bridged by a bypass vessel so that the narrowing can be bypassed by the blood flow and the downstream heart muscle tissue can be supplied again.
More than 80% of patients are free of symptoms after the operation. The right or left thoracic artery (Arteria thoracica interna) can be used as a bypass vessel, as can the radial artery of the hand or a femoral vein (Vena saphena magna). The two latter two vessels are prepared intraoperatively (during surgery) from their original anatomical position and used as an intermediate piece (interponate) to bridge the coronary arteries.
The radial artery (radial artery) can only be used as a bypass if the ulnar artery (olecranon artery) alone ensures the supply of the hand. The Allen test is used to check the blood circulation situation in the hand: In the run-up to the operation, the examiner squeezes the vessels on the right and left side of the wrist, where pulses can be felt. If the hand is whitish after a few seconds, he relieves the ulnar side of the wrist, the side of the wrist facing the little finger, and continues to exert pressure on the radial artery.
If the hand now turns pink again, the blood supply to the hand through the ulnar artery is ensured and the radial artery can be used for bypass surgery. If a venous bypass was performed, i.e. the coronary artery was bridged with the help of the femoral vein, the probability of occlusion is 20 – 30% in the first 5 years after the operation. The arterial bypass closes again in less than 10% after 10 years.
The risk of the operation is 1% mortality, the risk of suffering a heart attack during the operation is 5 – 10%. The post-operative treatment of the operated patients is done with antiplatelets (aspirin, clopidogrel), which inhibit blood clotting.
- The presence of a significant narrowing of more than 50% of the vessel cross-section
- Coronaries that are continuous in the distal (in the part downstream of the narrowing)
- A functional heart muscle behind the vascular constriction
- A coronary artery with a diameter of at least 2 mm so that a bypass vessel can be connected to it