Ann Thorac Surg 2001;71:41-42
© 2001 The Society of Thoracic Surgeons
Invited commentary: original article: cardiovascular
Invited commentary
Anthony J. DelRossi, MDa
a Department of Surgery, Division of Cardiothoracic Surgery, Robert Wood Johnson Medical School, 3 Cooper Plaza, Camden, NJ 08031, USA
e-mail: delrossi-tony{at}cooperhealth.edu
Cannulation of a friable left atrial appendage in left heart bypass can be difficult. The authors have quantified some of the complications with this route and point out their success using the pulmonary veins for cannulation. However, the debate surrounding spinal cord protection continues. The authors favor left heart bypass; however, they have not made a compelling argument for this technique. In their series the "clamp and sew" group had a 24% paraplegia rate. This is quite high. Others have reported a 5% incidence with either clamp and sew or bypass. Admittedly the authors’ patients were sicker and presented with an increased injury severity and had lower probability of survival. Finally, there were 10 additional minutes in the cross-clamp times of the clamp and sew group. Many were in shock and had blood pressures < 60 mm Hg. Although not statistically significant, an additional 10 minutes of clamp time probably contributes to the clinical level of spinal cord intolerance. The hemodynamically stable patients had left heart bypass and shorter clamp times and the results were excellent. The authors failed to mention many of the factors that contribute to paraplegia, ie, ischemia and reperfusion of the spinal cord, pharmacologic effects on blood pressure with concomitant increase in cerebral spinal fluid pressure, and shunting of blood from the spinal cord. Additionally, unfavorable anatomy, long cross-clamp times, multiple trauma, and timing of the operation are all variables. Even the authors agree, as they state that "mechanical support was not identified as being independently associated with the significant reduction in paralysis."
Unfortunately we do not understand the exact cause of paraplegia. So-called "medical experts" and their attorneys try to make the case for some form of bypass; however, they fail to understand that simple maintenance of distal aortic pressure alone does not protect from paraplegia. Rather than champion one technique over another, it would be helpful to recognize our limitations in preventing paraplegia and develop guidelines to reduce this dreaded complication. It has become clear that having an expert team available for this type of surgery in an active trauma center is important. Mild hypothermia is helpful and appropriate blood pressure control is essential. The latter can be achieved with either left heart bypass or pharmacologic manipulation with equally good results. Limiting the distance between the proximal and distal clamp and avoiding interruption of intercostal arteries is critical. Finally, the cross-clamp time should be kept to a minimum, usually less than 30 minutes. Heparin administration is debatable, especially with associated neurologic and pulmonary injuries. Paraplegia may not be totally eliminated because of its multifactoral etiology; however, attention to details, rather than reliance on one modality, will lessen the incidence.
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