Cardiac bypass surgery is the bridging of stenotic coronary vessels (narrowed coronary arteries) by means of coronary artery bypass (bypass or bridging; coronary artery bypass grafting (CABG)). The procedure is used for complex disease patterns with multiple and complexly narrowed coronary vessels.
Indications (areas of application)
- For coronary stenosis >70% that cannot be addressed interventionally.
- Main stem stenosis of the left coronary artery > 50%.
Note: The more complex the coronary anatomy, the more likely that bypass surgery will be considered as an option, assuming low surgical risk. The European Society of Cardiology (ESC) and European Association for Cardiothoracic Surgery (EACTS) guideline on bypass surgery for coronary artery disease (CAD) [see guideline below: 1] advocates coronary bypass surgery for:
- Three-vessel disease in which calcification of the arteries is very pronounced
- Main stem stenosis (narrowing in the area of origin of the left coronary artery/coronary artery).
- Concomitant diseases
- Diabetes mellitus
- Reduced left ventricular function (< 35%)
- Contraindications
- Dual antiplatelet therapy (DAPT).
- Recurrent stent stenosis
Revascularization recommendations in multivessel disease
| Extent of coronary artery disease | Bypass surgery | PCI* * |
| 1- or 2-vessel disease (2-GE) without proximal RIVA stenosis. | ↑ | ↑↑ |
| 2-GE with proximal RIVA stenosis* , SYNTAX score* * * (SyS) ≤ 22. | ↑↑ | ↑↑ |
| 2-GE with proximal RIVA stenosis, SyS ≥ 23 | ↑↑ | ↑ |
| 3-GE, SyS ≤ 22 | ↑↑ | ↑ |
| 3-GE, SyS ≥ 23 | ↑↑ | not recommended (n .e.) |
| 2 or 3-GE and diabetes mellitus. | ↑↑ | n. e. |
| Main stem stenosis (HSS) (proximal or medial) and SyS ≤ 22. | ↑↑ | ↑↑ |
| HSS (bifurcation) or HSS and SyS 23-32 | ↑ | ↑ |
| HSS SyS ≥ 33 | ↑ | n. e. |
* Ramus interventricularis anterior* * See “percutaneous coronary intervention (PCI)” for procedure details. * * * SYNTAX score is based on coronary anatomy and complexity of coronary lesions.
Before surgery
- Preoperative administration of acetylsalicylic acid (ASA) significantly reduced the rate of postoperative myocardial infarction/heart attack (from 5.6% to 2.8% (odds ratio 0.56; 95% confidence interval 0.33-0.96)). Moreover, at low daily doses, there was no difference for blood loss via chest drainage (drainage system used to drain fluids and/or air from the chest (thorax)) compared with the group without ASA therapy.
- A randomized clinical trial concludes that low-dose acetylsalicylic acid (ASA) treatment need not be interrupted before planned bypass surgery. Severe bleeding requiring reoperation occurred in 2.1 percent of patients in the placebo group and in only 1.8 percent in the ASA group. The primary endpoint, a combination of thrombotic complications (nonfatal apoplexy (stroke), myocardial infarction (heart attack), pulmonary embolism, renal failure or mesenteric infarction (bowel infarction)) and death within 30 days of surgery, also supports this conclusion. Primary end point in the:
- ASA group in 202 patients (19.3%).
- Placebo group in 215 patients (20.4%).
- The American College of Cardiology Foundation (ACCF) and the American Heart Association (AHA) recommend that ASA treatment be continued in CHD patients until the day before surgery.
- The European Society of Cardiology (ESC) advises discontinuation of ASA treatment in patients at high risk of bleeding and low risk of thrombosis.
The surgical procedure
In conventional bypass surgery, the thorax (chest) is opened. In this case, coronary revascularization is performed with the use of a heart-lung machine to maintain circulation (extracorporeal circulation) with the performance of anastomoses (“formation of connecting ducts”) on the beating, fibrillating or, in most cases, cardioplegically arrested heart.Minimally invasive bypass surgery eliminates the need for a heart-lung machine and avoids manipulation of the aorta. The procedure is called OPCAB (off-pump coronary artery bypass) when the thorax is opened median (in the middle) and MIDCAB (Minimally Invasive Direct Coronary Artery Bypass).when the thorax is opened on the left side. To bypass narrowed coronary arteries, veins – usually the saphenous vein – are usually used, which are taken from the lower leg (aortocoronary vein bypass, ACVB; coronary artery bypass graft, CABG). This method is the most widely used, but if a suitable vein cannot be found, plastic interposition devices can also be used. In addition to these methods, a so-called mammary coronary bypass (internal mammary artery (LIMA)) can also be used, in which an artery from the thorax is used for bridging. This is used primarily in young individuals because of its very long shelf life. However, the vessel is not very long, so it cannot be used for all stenoses (narrowings).If necessary, use of coronary bypasses using the radial artery (see “Additional Notes” below).
After surgery
- Patients undergoing surgical revascularization (restoration of blood flow) after acute coronary syndrome are recommended dual antiplatelet therapy.
Potential complications
- Cardiac arrhythmias such as ventricular fibrillation.
- Myocardial infarction (heart attack)
- Sudden cardiac death (PHT)
- Apoplexy (stroke)
- Restenosis – renewed narrowing of a vessel.
- Pericarditis (inflammation of the pericardium)
- Wound healing disorders and wound infections
- Bleeding
- Nerve or vascular damage
The operation is performed under general anesthesia.The lethality (mortality related to the total number of people suffering from the disease) during the operation is up to three percent. Bypass surgery is a major operation that is often the only way to effectively help a patient. Further notes
- Botulinum toxin injection into epicardial adipose tissue may prevent the occurrence of supraventricular tachyarrhythmias after bypass surgery, according to one study. In the Botox group, atrial arrhythmias occurred in two cases (7%) after 30 days, while in the control group, arrhythmias occurred in nine patients (30%). The difference was also significant one year after surgery: no further arrhythmias occurred in the Botux group compared to seven cases in the control group.Note: Approximately one third of all patients are affected by supraventricular tachyarrhythmias during this procedure. These are classically treated a beta-blocker.
- Bypass surgery without a heart-lung machine (off pump) has not achieved any long-term advantages over conventional on-pump surgery in a multicenter study (79 hospitals in 19 countries). This also affects all secondary endpoints (death, myocardial infarction (heart attack), apoplexy (stroke), renal failure requiring dialysis (kidney weakness), repeat revascularization/reopening of vessels).
- Bypass failure over 20 years depending on the type of bypass:
- Internal mammary artery (LIMA): 19%.
- Radial artery (RA). 25 %
- Vv. saphenae magnae: 55 %
Difference between RA bypass and vein bypass: statistically significant (p = 0.002); between RA and LIMA: no significant difference.
- 10-year data from the STICH study: patients with ischemic cardiomyopathy (myocardial insufficiency resulting from reduced blood flow to the. Cardiac muscle tissue) and lowered left ventricular ejection fraction (ejection fraction) (of the left ventricle) live longer by bypass surgery (on average 18 months more life).
- Compared with the use of saphenous vein grafts, the use of radial artery grafts for coronary artery bypass grafting (CABG) resulted in a lower rate of adverse cardiac events and a higher patency rate at 5 years of follow-up.
