Ann Thorac Surg 2001;71:1070-1072
© 2001 The Society of Thoracic Surgeons
Correspondence
Selective graft and coronary sinus perfusion in off-pump CABG: is it necessary?: Reply
Harinder Singh Bedi, MCha
a Tagore Heart Care & Research Centre, 339 GTB Nagar, Jalandhar, Punjab 144003, India
e-mail: bedi{at}jla.vsnl.net.in
To the Editor
We thank Ricci and colleagues for their interest in our manuscript. They have raised crucial points regarding our technique of coronary sinus and graft perfusion during off-pump CABG. One of the main factors in off-pump CABG, which will affect graft patency, and so the onset of any major adverse cardiac-related event is the precision of the coronary anastomosis. If there is a "race against the clock" while performing the grafting on a beating heart then it can definitely jeopardize the accuracy of the suturing.
It would be naive to believe that ischemia does not occur when a coronary artery is snared during construction of an anastomosis. In fact the authors state that they routinely use an intracoronary shunt during grafting. We are a little wary of shunts because of the inherent risk of producing damage to endothelium [1], risk of dissection, dislodgement of atheroma, risk of air and particulate embolism, hindrance with suturing and at times a difficulty in insertion.
A recent report by Svedjeholm and colleagues [2] and previous elegant work on pressure-controlled intermittent coronary sinus perfusion (PICSO) and arterial retroperfusion of the coronary sinus [3] show that retrograde perfusion does work in reducing ischemia in patients with coronary artery disease. In fact, in the same issue of the Annals of Thoracic Surgery, an article by Martin and colleagues [4] shows that LV powered coronary sinus retroperfusion reduces infarct size in acutely ischemic pigs.
It is a fact that manipulation of the heart by whatever technique does produce unfavorable hemodynamic consequences. When these are coupled with the regional ischemia that will invariably be produced when a coronary artery is snared, the combination can be dangerous. A combination of "little" effects (a "little" hemodynamic compromise, a "little" ischemia, a "little" aortic regurgitation, a "little" drop in temperature, etc) can combine to produce a major problem. We strongly believe that the ability to perform an off-pump CABG successfully and precisely lies in attention to all details. Every little extra keeps us on the right side of the safety line and gives a safety net in what is essentially a "new" procedure. Retrograde perfusion is quite safe because in the majority of cases the pressure in the coronary sinus does not go above the arbitrary level of a mean of 40 mm Hg [5] (Fig 1) even when the systemic pressure is high. We have noted a proof of perfusion by way of the following facts:
- ECG changes on snaring an artery that revert to normal on starting retrograde perfusion.
- Vigorous backbleeding of dark blood on temporary release of distal snare after arteriotomy (Fig 2).
- A good oxygen extraction ratio (across the LAD and circumflex area) of 46% ± 4% was noted in 10 patients.
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Fig 1. Freeze frame of the monitor showing the coronary sinus pressure (labeled RV) with perfusion off (star) and on (arrow). Even at a systemic pressure of 153 mm Hg systolic the mean coronary sinus pressure is 30 mm Hg.
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Fig 2. Intraoperative photograph showing the vigorous backbleeding (arrow) of dark blood from the site of arteriotomy with the distal snare not snugged down. (Ante = antegrade cannula; R = retrograde cannula; A = site of arteriotomy.)
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This high extraction is suggestive of the fact that the myocardium is using up the oxygen being delivered by the retrograde route.
Similar results (reversion of ECG changes) have been reported with perfusion-assisted direct coronary artery bypass [6]. "Active" perfusion using a pump is logically an excellent way of avoiding ischemia. However it does not avoid ischemia during the construction of the first graft (which, in the series reported, is not the left internal mammary artery to the left anterior descending artery [LIMA to LAD]) and the flow to the area being grafted is dependent on the degree of collateralization between the perfused vessel and the vessel being grafted. Also we are not quite sure that suprasystemic perfusion of the grafts is a good idea because of the inherent risk to the integrity and function of the endothelium of the vein or radial artery.
We are in total agreement with the authors regarding the sequence of grafting and have already very clearly mentioned (under "sequence of grafting") doing the easiest grafts first, which usually translates to a LIMA to LAD. We also agree that the LIMA to LAD graft neither prevents nor hinders the ability to manipulate the heart when additional coronary targets are grafted.
We share the concern of the authors regarding the drop of aortic pressure when the heart is elevated. Obviously marked hypotension per se is unacceptable. Aortic pressure is maintained by volume loading, head down position, and short-term pharmacologic measures (vasoconstrictors).
The authors state that our technique may be of use only in cases with severe and diffuse disease. However what is good for a "bad" case is also going to be good for a "good" case. With retrograde perfusion we have noted that our anastomosis time has actually gone up as we have been able to perform an unhurried anastomosis taking each stitch under direct vision without worrying about the coronary clamp time. The effect of this on graft patency should logically be a favorable one. The beauty of the technique of coronary sinus and graft perfusion lies in its efficacy, simplicity (Fig 3), and ease of execution and control.
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Fig 3. Intraoperative photograph showing the simplicity of the technique and perfusion of grafts and coronary sinus. (A = antegrade cannula; R = retrograde cannula; Ra = radial artery to posterior descending artery being perfused by a multiport from the ascending aorta; RA = right atrium; Rima = right internal mammary artery to right coronary artery graft.)
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References
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Chavanon O., Perrault L.P., Menasché P., Carrier M., Vanhoutte P.M. Endothelial effects of hemostatic devices for continuous cardioplegia or minimally invasive operations. Ann Thorac Surg 1999;68:1118-1120.[Free Full Text]
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Svedjeholm R., Hakanson E., Forsman M. Treatment of acute myocardial ischemia during early stages of surgery by an easily applicable method for emergency retroperfusion. Eur J Cardiothorac Surg 1999;15:551-552.
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Gundry S.R. Modification of myocardial ischemia in normal and hypertrophied hearts utilizing diastolic retroperfusion of the coronary sinus. J Thorac Cardiovasc Surg 1982;83:659-669.[Abstract]
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Martin J.S., Byrne M.D., Ghez O.Y., Sayeed-Shah U., Grachev S.D., Laurence R.G., Cohn L.H. LV powered coronary sinus retroperfusion reduces infarct size in acutely ischemic pigs. Ann Thorac Surg 2000;69:90-95.[Abstract/Free Full Text]
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Eke C.C., Gundry S.R., Fukushima N., Bailey L.L. Is there a safe limit to coronary sinus pressure during retrograde cardioplegia?. Am Surg 1997;63:417-420.[Medline]
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Guyton R.A., Thourani V.H., Puskas J.D., et al. Perfusion assisted direct coronary artery bypass: selective graft perfusion in off-pump cases. Ann Thorac Surg 2000;69:171-175.[Abstract/Free Full Text]
Related Article
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Selective graft and coronary sinus perfusion in off-pump CABG: is it necessary?
- Marco Ricci, Giuseppe D’Ancona, Jacob Bergsland, Tomas A. Salerno, and Hratch L. Karamanoukian
Ann. Thorac. Surg. 2001 71: 1069-1070.
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