| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
|
|
|
|||||||
|
|||||||||
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Ann Thorac Surg 2000;70:1760-1761
© 2000 The Society of Thoracic Surgeons
a Thoracic and Cardiovascular Surgery Department, University Hospital, Avenue de la "Cote de Nacre", 14033 Caen, France
e-mail: massetti-m{at}chu-caen.fr
To the Editor
I would like to congratulate Chaudhuri and Hickey for their original technique, concerning the treatment of coronary air embolism after cardiopulmonary bypass, published in the November 1999 issue of The Annals [1]. Nevertheless, I would like to make some comments.
Air embolism during open heart operation is especially regrettable because it is iatrogenic. Its origin, besides the accidents during extracorporeal circulation, is the air trapped inside the heart and in the coronary circulation. Although the heart chambers are easy to purge, coronary circulation remains the most difficult compartment from which to remove air bubbles. During in vitro and in vivo studies [2], the fate of injected microbubbles through the capillary bed show them to coalesce or temporarily obstruct the flow, and subsequently to shrink or collapse. Regional myocardial dysfunction and focal necrosis may result after the release of the aortic clamp [3]. Different techniques have been reported to enhance air removal from the coronary vessels, and many of these are based on augmentation of coronary perfusion pressure to supernormal levels in an effort to push the air across the capillary bed to the venous circulation. Such methods have included mechanical systole, increasing the pump flow rate, administration of vasopressors, and, as Chaudhuri and Hickey reported, reclamping the ascending aorta and injecting a syringe of blood under pressure [1]. Several experimental studies have documented the potential risks of these methods. The high perfusion pressures required to rid the coronary arteries of air may damage endothelium, cause interstitial hemorrhage, and exacerbate myocardial ischemia. Van Blankestein and associates in their experimental study [4], demonstrated that blood pressure as high as 200 mm Hg was required to drive air emboli through capillary vessels 6 µm in diameter. Sandhu and colleagues demonstrated experimentally that coronary air embolism treatment with antegrade cardioplegia resulted in diminished left ventricular performance compared with the treatment with retrograde cardioplegia [5]. For many years, our group has used a complementary maneuver for dearing coronary vessels before releasing the aortic clamp. This technique consists of augmenting pressure in the right side of the heart. With the right atrium maintained at 15 to 20 mm Hg and main pulmonary artery clamped (manually or by a clamp), manual compressions of the right heart are repeated. Under this condition, the right atrial pressure rises 60 to 80 mm Hg, producing a retrograde purge of the coronary system through the coronary sinus and thebesian veins. Air bubbles trapped in the coronary system are easily pushed towards the aorta and cleared away [6].
Another advantage with the retrograde techniques is that the aorta does not need repeated clamping, which has the potential for wall lesions and emboli. In conclusion, we think that coronary air embolism must be prevented, but if it is suspected, a retrograde purge technique is preferred because it dislodges air emboli and restores blood flow.
References
Related Article
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
| ANN THORAC SURG | ASIAN CARDIOVASC THORAC ANN | EUR J CARDIOTHORAC SURG |
| J THORAC CARDIOVASC SURG | ICVTS | ALL CTSNet JOURNALS |
