Question

REVIEW QUESTIONS 1. Why are multiple prep sites often required in cardiac surgery? 2. What are the specific characteristics of cardiac clamps that differentiate them from other types of clamps? 3. Several techniques are used to isolate and manipulate blood vessels during cardiac surgery. Describe at least two. 4. What is the purpose of suture pledgets? 5. What instruments are needed to divide the sternum? 6. What is the atrial appendage? 7. What technique is often used in valve surgery to help the surgeon identify pairs of sutures between the valve and the annulus? 8. List all the drugs and solutions (and their basic action) likely to be needed and managed by the surgical technolo- gist during open heart surgery. Be sure to include hemo- static agents and tissue adhesives. 9. During cardiopulmonary bypass, the heart may be delib- erately stopped. What technique is used to stop the heart? What technique is used to start it again? 10. What are the basic indications for implanting a left ven- tricular assist device?

Answer 1

3. For anastomoses to target coronary arteries during coronary artery bypass graft (CABG) surgery, different continuous suture techniques have been used . A competent anastomotic technique can achieve satisfactory antegrade and retrograde arterial patency in the anastomotic sites of the target coronary arteries and grafts. Here, we introduce a simple technique for obtaining satisfactory anastomosis of coronary arteries and grafts in patients who have small coronary arteries (<1.2 mm) or marked size discrepancies between the target coronary arteries and grafts.

Technique

1) Distal anastomosis of a graft to a target coronary artery

For distal anastomosis of the graft to the coronary artery, we used a continuous suture technique with two suture materials. For this method, the graft is anchored to the proximal and distal ends of the coronary arteriotomy with three stitches on each end using two 7-0 or 8-0 polypropylene monofilaments. The length of the coronary arteriotomy should be 20% shorter than the beveled length of the graft, thus leaving a hood. In detail, the first three-stitch continuous suture is placed counterclockwise at the heel of the graft and at the proximal end of the coronary arteriotomy. After the graft is anchored, two ends of the suture are grasped with two silicone-shod clamps . Next, with the second suture material, the toe of the graft is anchored to the distal end of the coronary arteriotomy, again using the same technique (continuous counterclockwise stitches) . The second suture is continued counterclockwise toward the starting point of the first heel suture and tied. At this time, three lumens of the anastomosed graft and the proximal and distal ends of the coronary arteriotomy may be carefully checked with a 1-mm flexible probe. The opposite suture line is completed counterclockwise with the other arm of the first heel suture .

2) Sequential anastomosis of the graft to the coronary arteries

For sequential graft anastomoses to coronary arteries, the arteriotomy length is approximately 1.5 times the arterial diameter and the graft incision should be 20% longer than the arteriotomy. Rather than a continuous technique, the interrupted eight-stitch technique in a diamond configuration is used to avoid the purse-string effect and obtain a sufficient anastomotic opening . In detail, three interrupted sutures using 7-0 or 8-0 polypropylene monofilament are first placed in the proximal side of the coronary arteriotomy, through the graft, and then tied into place. The remaining five interrupted sutures are then placed at even intervals and tied . This method can result in a large anastomotic opening associated with satisfactory hemostasis

4. Pledgets or felts are non-absorbable materials composed of poly-tetra fluoro ethylene (PTFE) and are are indicated for use as non-absorbable suture supports when there is a chance of sutures tearing through body tissues.

5. Novo Surgical's Lebsche Sternal Chisel is an instrument commonly used in cardiothoracic procedures specifically in procedures involving splitting the sternum. This chisel is ideally used in a midline sternotomy where it is necessary to make an incision and create a split down the midline of the sternum.

A sternal saw is a bone cutter used to perform median sternotomy, opening the patient's chest by splitting the breastbone, or sternum. It is a reciprocating blade saw that resembles a jigsaw in appearance .

6. The left atrial appendage (LAA) is derived from the left wall of the primary atrium, which forms during the fourth week of embryonic development. It has developmental, ultrastructural, and physiological characteristics distinct from the left atrium proper. The LAA lies within the confines of the pericardium in close relation to the free wall of the left ventricle and thus its emptying and filling may be significantly affected by left ventricular function. The physiological properties and anatomical relations of the LAA render it ideally suited to function as a decompression chamber during left ventricular systole and during other periods when left atrial pressure is high. These properties include the position of the LAA high in the body of the left atrium; the increased distensibility of the LAA compared with the left atrium proper; the high concentration of atrial natriuretic factor (ANF) granules contained within the LAA; and the neuronal configuration of the LAA. Thrombus has a predilection to form in the LAA in patients with atrial fibrillation, mitral valve disease, and other conditions. The pathogenesis has not been fully elucidated; however, relative stasis which occurs in the appendage owing to its shape and the trabeculations within it is thought to play a major role. Obliteration or amputation of the LAA may help to reduce the risk of thromboembolism, but this may result in undesirable physiological sequelae such as reduced atrial compliance and a reduced capacity for ANF secretion in response to pressure and volume overload.

9. Cardioplegia. Cardiopledgia is a fluid solution used to protect the heart during CPB. It is delivered via a cannula to the opening of the coronary arteries (usually by way of the aortic root) and/or to the cardiac veins (by way of the coronary sinus). cardioplegia solution is administered to allow the cardiac surgeon to operate on a nonbeating heart in a field largely devoid of blood, while other end organs remain adequately oxygenated and perfused .

10. Over the past several years, there has been a dramatic shift from the use of large pulsatile left ventricular assist devices (LVADs) to the use of smaller continuous-flow devices for the provision of mechanical circulatory support in patients with heart failure. [1] However, the fundamental issues related to surgical implantation remain the same. That is, most devices use the apex of the left ventricle (LV) as the inflow site to the pump, which subsequently gives off an outflow graft to the aorta, thus bypassing the ailing LV.

• Age.
• Diabetes.
• Pulmonary hypertension.
• Renal dysfunction.
• Recent malignancy.

1. Cardiac surgery represents high operative and perioperative risk requiring professional staff and advanced equipment. Besides the diseases that require cardiac surgery, the perioperative period shows a variety of characteristic pathologies: systemic inflammatory response following CBP, myocardial stunning and low cardiac output syndrome, arrhythmias, massive transfusion requirements and multiorgan involvement with kidney injury, stroke, and respiratory distress.

7. The purpose of this study was to determine which of four suture methods for mitral valve replacement maximized prosthetic stability in the mitral anulus. Horizontal mattress sutures with subannular pledgets, horizontal mattress sutures with supra-annular pledgets, figure-of-eight sutures, and interrupted simple sutures were compared. A Carpentier-Edwards sewing ring was sutured to the mitral anulus of intact canine left ventricles, each technique randomly assigned to eight hearts. Suture size, number of bites, and annular depth were maintained constant in all groups. Progressively increasing force was applied across the suture line until disruption occurred. The yield force at initial suture disruption was measured by a semiconductor strain-gauge transducer and defined the experimental end point. Subannular pledget-supported sutures required the greatest force (38.4 +/- 0.8 N) to produce prosthetic dehiscence and were significantly more secure than supra-annular pledgets (32.7 +/- 0.5 N). The two suture techniques in which pledgets were used were better than the nonsupported sutures, the mean yield force averaging 28.3 +/- 0.3 N for figure-of-eight and 21.3 +/- 0.7 N for interrupted simple sutures. Although clinical techniques may vary with prosthetic valve design, surgical preference, or pathological anatomy, this study suggests that horizontal mattress sutures with subannular pledgets provide the best prosthetic valve stability during mitral valve replacement.