Indications and diagnostics
The absolute indication for the surgery is coronary artery disease (CAD). It is crucial to differentiate this condition: CABG is not used to treat dilated cardiomyopathy, rheumatic heart disease, or infective endocarditis.
A mandatory condition for a successful bypass is the presence of an adequate outflow bed — preserved patency of the distal segments of the coronary arteries must be confirmed. The main diagnostic reference point when planning the scope and tactics of the surgical intervention is the objective data from coronary angiography.
Surgical approach and equipment
The classic approach for performing aortocoronary bypass surgery is median sternotomy, which provides wide exposure of the anterior mediastinum and the heart.
The surgery is usually performed using a cardiopulmonary bypass (CPB) machine. In certain cases, when there is isolated disease of the major coronary arteries, the procedure can be performed on a beating heart without CPB. However, even in this case, the cardiopulmonary bypass machine must be fully prepared and present in the operating room for emergency use.
Graft preparation
Autografts are used to create the bypass shunt. Harvesting the material is performed as follows:
- A segment of the great saphenous vein (vena saphena magna). Harvesting of the venous graft on the thigh is performed by a second surgical team simultaneously with the main stage on the chest.
- A segment of the internal thoracic artery (arteria thoracica interna).
Anastomosis technique
The surgery requires high-precision microsurgical technique and is performed in a strict sequence:
- Isolation of the coronary artery. The vessel is carefully dissected from the epicardial fat bed. The artery must be ligated and transected strictly distal to the occlusion (not at the ostium level, proximal to the occlusion, or in the bifurcation area).
- Creation of the distal anastomosis. Performed between the prepared graft and the distal segment of the coronary artery in an end-to-end fashion. To facilitate suturing, a special probe is passed through the graft into the lumen of the artery.
- Creation of the proximal anastomosis. The ascending aorta is clamped using a side-biting clamp. An oval opening is cut into the aortic wall using a scalpel and scissors. The graft is sutured to the aorta in an end-to-side fashion.
- Completion of the operation. The surgeon removes the clamp from the ascending aorta, restoring blood flow through the new pathway. In diffuse atherosclerosis, simultaneous bypassing of two or three arteries is possible.
Resumo: perguntas e respostas sobre o tema
Which vessels, besides the internal thoracic artery and the great saphenous vein, can be used as grafts in CABG?
In addition to the internal thoracic artery and the great saphenous vein, the radial artery can be used as a graft in aortocoronary bypass surgery.
- Radial artery (a. radialis) — its use in modern surgery is made possible by a good collateral network in the forearm, which can compensate for restricted or complete cessation of blood flow through the main artery.
Which anatomical layers are sequentially incised during a median sternotomy?
During a full longitudinal sternotomy, the soft tissues of the anterior chest wall and the bone itself are sequentially incised.
During the surgical approach, the following layers are incised:
- Skin — incised longitudinally along the entire sternum.
- Fascia — incised following the skin.
- Periosteum — incised along the sternum, after which its edges are electrocoagulated.
- Sternum — transected using a sternotome, Gigli saw, chisel, or electric circular saw after creating a tunnel behind the sternum.
Rule for creating anastomoses in CABG: first the "DISTAL" one (to the transected coronary artery — end-to-end), then the "PROXIMAL" one (to the ascending aorta — end-to-side).
Questões de aulas e exames
Where exactly should the coronary artery be transected during CABG?
The artery is isolated from the epicardial bed, ligated, and transected strictly distal (below) to the site of occlusion to direct blood flow into a healthy vascular bed.
Are infective endocarditis or rheumatic heart disease indications for CABG?
No, CABG is performed for coronary artery disease (CAD). Rheumatic heart disease, dilated cardiomyopathy, and infective endocarditis are not direct indications for coronary artery bypass grafting.
Can aortocoronary bypass surgery be performed without CPB?
Yes, in case of isolated lesions of major arteries, the surgery is possible without connecting cardiopulmonary bypass, but the machine must always be prepared in advance in the operating room.
Which vessels are most commonly used as grafts?
A segment of the great saphenous vein (harvested from the thigh by a second team) and a segment of the internal thoracic artery are used.
O que mais estudar sobre o tema
- Topographic anatomy of the great saphenous vein of the thigh
- Course and branches of the internal thoracic artery in the mediastinum
- Topography of the epicardial bed and coronary sulci of the heart
- Technique of performing median sternotomy
- Princípios de funcionamento do aparelho de circulação extracorpórea (CEC)
- Interpretation of coronary angiography results
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