Beating Heart Surgery - Coronary Occlusion

CORONARY OCCLUSION

With CPB, a clear anastomotic site is obtained by cross-clamping the aorta, which stops all blood flow through the coronary arteries. In beating heart CABG, only proximal occlusion of the target coronary artery is required. Distal occlusion has not been found to be necessary unless poor visibility jeopardizes the precision of the anastomosis.

"Vessel occlusion is important from an antegrade flow perspective. We use a specially designed, very short-nosed bulldog." ¹³ -David Perkowski, M.D.

Many techniques for coronary artery occlusion are currently being used in conjunction with stabilization technology to prevent coronary trauma. In the following technique, a pledget and silastic tape are used to apply occlusion pressure (Figure 9):

1. Place pledgeted silastic tape around the coronary artery.

2. Perform the arteriotomy while blood is flowing through the artery in order to minimize the risk of perforating the back wall of the artery.

3. Slide the pledget down while gently pulling up on the silastic tape just to the point of hemostasis.

4. Place a small titanium ligaclip on the silastic tape to maintain the occlusion.

Figure 9. Coronary occlusion with silastic tape and pledget

VISUALIZATION/BLOODLESS FIELD

In order to effectively perform an anastomosis on a coronary artery, whether or not the heart is beating, the anastomotic site must be cleared of blood to allow visualization for accurate suturing.

Several visualization devices are available on the market because a perfectly bloodless field is rare in beating heart CABG. Humidified air (e.g., Medtronic ClearView™ Misted Blower) has been shown to safely and effectively clear arteriotomies of excess blood and "parachute" open the arteriotomy to assist in suturing. The following parameters for misted blower devices provide sufficient humidification while preventing dessication of the coronary endothelium and surrounding tissue:²⁰

Medical air flow at 2Ð5 L/min
Saline solution at 10Ð50 ml/min under 150 mmHg pressure
Device held 5Ð10 cm from the anastomotic site
Malleable shaft to allow for unobstructed view of the target area

"It is critical to have an assistant who understands the use of the humidified CO₂ jet so you can see each suture."¹³ -James C. Hart, M.D.

"We also use a blower/mister to clear the field of any other blood that's coming retrograde. It is essential. You can't do [beating heart CABG] without having a blower/mister."¹³ -David Perkowski, M.D.