This is a diagram of the left coronary artery and its main branches in the right anterior oblique view. After a short course, the left main coronary artery typically divides into two vessels, the left anterior descending and the circumflex artery. The major branch of the left anterior descending is the diagonal artery. The main branch of the circumflex is the obtuse marginal artery.
Left coronary RAO view video
This left coronary angiogram demonstrates a high-grade stenosis of the left anterior descending coronary artery. A stenosis of the first obtuse marginal branch of the circumflex is also well seen. In the real-time study that follows, note the poor flow in the left anterior descending coronary artery distal to the occlusion.
Results
The most critical obstruction in our patient is located in the left anterior descending coronary artery with an additional lesion in the obtuse marginal branch of the circumflex. A separate injection of the right coronary artery (RCA) demonstrated a seventy percent lesion.
Acute setting
In this acute setting, it is difficult to differentiate ischemic, or "stunned" myocardium from infarcted tissue. The short time from the onset of our patient's symptoms makes it likely that a significant amount of myocardium is ischemic and still viable.
PCI
It was decided to proceed with PCI, or percutaneous coronary intervention. Achieving rapid reperfusion of the left anterior descending coronary artery is the best way to minimize the size of this patient's infarction. In this setting, percutaneous coronary intervention is the therapy of choice for revascularization. PCI includes a variety of procedures, such as angioplasty and stent placement. An alternative may be thrombolysis. Although the patient has lesions in each of the three major coronary artery branches, the myocardial ischemia was precipitated by the high-grade stenosis of the left anterior descending coronary artery. It is the "culprit" lesion.
Angioplasty & stent diagram
The following diagram demonstrates percutaneous transluminal coronary angioplasty and intracoronary stent placement. A small deflated plastic balloon is passed to an area of coronary artery obstruction with the aid of a guide wire. A stent, mounted over the deflated angioplasty balloon is positioned at the site of the lesion. In the upper panel, a deflated balloon is shown straddling the coronry artery stenosis. In the lower panel, the balloon has been inflated, leading to compression and splitting of the coronary artery plaque with relief of coronary obstruction. Correct stent deployment results in a decrease in elastic recoil of the coronary artery and decreases the incidence of coronary restenosis. Drug eluting stents further decrease the incidence of in-stent restenosis, but are associated with an increased risk of very late stent thrombosis, compared to bare metal stents. The incidence of very late stent thrombosis is six tenths of a percent annually and may persist indefinitely.
Inflated balloon still
In our patient, balloon angioplasty and stent placement were performed. This is a still-frame of the inflated balloon and guide wire in the stenosed left anterior descending coronary artery.
Antiplatelet therapy
Dual antiplatelet therapy is indicated for high-risk acute coronary syndrome, including STEMI, and was considered for our patient to improve vessel patency. Choices include P2Y2 inhibitors, such as clopidogrel, and GP IIb/IIIa inhibitors, such as abcixifiban. Strategies are evolving to minimize the use of GP IIb/IIIa inhibitors prior to coronary angiography, to reduce bleeding complications and improve outcomes. The decision was made to begin our patient on oral clopidogrel following successful stent placement.
Our patient
Urgent coronary artery bypass graft surgery, or CABG surgery was not necessary, as our patient's stent placement was successful and her hemodynamics improved. If percutaneous coronary intervention had not been successful, the patient would have been immediately transferred to the operating room.
CABG - another patient
The following coronary artery bypass graft surgery is presented through the courtesy of Drs. Sanford Finck and Harold Snyder and was carried out at the Mayo Clinic in Jacksonville, Florida.
A median sternotomy incision has been made and the left internal mammary artery dissected off the chest wall. The artery is large and had excellent flow. A small temporary vascular clamp is applied to the artery to occlude flow while it is being prepared for bypass.
The internal mammary artery is being prepared to place over the left anterior descending coronary artery to show that it is of sufficient length to allow an anastomosis. After the patient has been prepared for cardiopulmonary bypass, the aorta is cross-clamped and cardioplegic solution is given to arrest the heart. The heart is also bathed in iced saline to cool and further protect the myocardium.
The distal end of the saphenous vein bypass graft to the obtuse marginal branch of the circumflex artery is aligned and sutured end-to-side in place. Once completed, the sutures are tied with care to ensure hemostasis of the suture line. The proximal saphenous vein graft segment will be sized and cut in preparation for anastomosis to the aorta.
The remaining saphenous vein will be used for bypass of the right coronary artery.
Following completion of the distal saphenous vein graft anastomoses, the left internal mammary artery anastomosis to the left anterior descending coronary artery will be completed.
After the aortic cross-clamp has been removed, the heart is electrically defibrillated.
The last step in the bypass procedure is the anastomosis of the proximal end of the saphenous vein graft to the ascending aorta, as shown here.
Following completion of the bypass graft anastomoses, the patient was weaned from cardiopulmonary bypass, drainage catheters and temporary pacemaker wires were inserted and the chest closed to complete the operation.