Myocardial protection in beating heart cardiac surgery: I: pre- or postconditioning with inhibition of es-ENT1 nucleoside transporter and adenosine deaminase attenuates post-MI reperfusion-mediated ventricular fibrillation and regional contractile dysfunction.

OBJECTIVE: To determine the role of the p-nitrobenzylthioinosine-sensitive equilibrative nucleoside transporter 1 (es-ENT1) in postmyocardial infarction reperfusion injury-mediated ventricular fibrillation and regional dysfunction. We used erythro-9 (2-hydroxy-3-nonyl)-adenine and p-nitrobenzylthioinosine to inhibit both adenosine deamination and transport in a canine model of off pump acute myocardial infarction. METHODS: Anesthetized adult dogs (n = 37), instrumented to monitor the percentage of systolic segmental shortening and wall thickening using sonomicrometry, underwent 90 minutes of left anterior descending coronary artery occlusion and 120 minutes of reperfusion. Myocardial coronary blood flow, adenosine triphosphate pool, infarct size, and the incident of ventricular fibrillation and cardioversion were also measured. The dogs received an intravenous infusion of the vehicle (control) or 100 µM of erythro-9 (2-hydroxy-3-nonyl)-adenine and 25 µM p-nitrobenzylthioinosine before ischemia (preconditioning group) or just before reperfusion (postconditioning group). RESULTS: In the control group, adenosine triphosphate depletion was associated with the accumulation of more inosine than adenosine during ischemia and washed out during reperfusion. Myocardial adenosine and inosine were the major nucleosides in the pre- and postconditioning groups during ischemia and remained detectable during reperfusion. In both groups, recovery of systolic segmental shortening and wall thickening and a reduction in the incidence of ventricular fibrillation (P < .05 vs the control group) coincided with retention of myocardial nucleosides. The infarct size in the 3 groups was not significantly different, independent of myocardial blood flow during ischemia. CONCLUSIONS: Preconditioning or postconditioning with erythro-9 (2-hydroxy-3-nonyl)-adenine/p-nitrobenzylthioinosine significantly reduced the incidence of ventricular fibrillation and cardioversion and attenuated regional contractile dysfunction mediated by postmyocardial infarction reperfusion injury. It is concluded that p-nitrobenzylthioinosine-sensitive equilibrative nucleoside transporter 1 played a major role in these events.

Open anterior approaches for lumbar spine procedures.

With the advent of anterior lumbar interbody fusion (ALIF) and artificial discs as common procedures for the treatment many spinal problems such as pseudoarthrosis, degenerative disc disease and internal disc disruption from trauma, anterior exposure has become an increasingly popular procedure for the general, thoracic, urologic and vascular surgeon. Despite this, the body of literature describing this procedure is lacking. Dividing the approach for anterior spinal surgery into the thoracolumbar, mid-lumbar, and lumbosacral regions, we describe the basic techniques and anatomy needed to perform these open approaches, specifically, repairs of disc spaces T12-L2, L2-5, and L5-S1, respectively. The technique for the retroperitoneal approach will be discussed in detail; however, issues involved with indications for transperitoneal approach and technical "pearls" will also be discussed.

Revision open anterior approaches for spine procedures.

BACKGROUND CONTEXT: Anterior exposure has become an increasingly popular procedure for the general and vascular surgeon due to the increased use of anterior lumbar interbody fusion and artificial disc replacement for the treatment of many spinal problems. PURPOSE: Because of this increase, revision operations have become increasing necessary. Despite this, there is almost no literature dealing with the issues related to these complex revision operations. STUDY DESIGN: A retrospective review of charts was performed on patients operated on from April 2002 until October 2004 in two tertiary care hospitals. METHODS: In total, 218 open exposures for anterior lumbar spinal approaches were performed of which 9 patients required revision lumbar spinal operations. Seven patients were approached again anteriorly (78%), and 2 (22%) patients required a combined anterior and posterior approach. RESULTS: The nine cases were the number of revision procedures performed over the 16-month period of this study. The average age was 44 overall (range, 25-89) and 53 (33-73) for the revision operations, p>.05. All revision operations attempted were successful. Seven (78%) of the secondary procedures could be approached retroperitoneally whereas 2 (22%) patients required transperitoneal approaches owing to the degree of adhesions. The average length until revision surgery was 13 months (range 6-24). No patients required early revision defined as surgery within 30 days from the primary surgery. Early complications occurred in 4 patients (44%), and included dural tear, median nerve dysthesia, left common femoral nerve palsy further complicated by prolonged postoperative ileus and retrograde ejaculation. Late complications occurred in one patient and consisted of a deep venous thrombosis and urinary tract infection. The average length of stay was 6 days (SD 2.7 days) (range 4-12) compared with 4 days (SD 2.3 days) (range 2-22) for the index operations, p>.05. CONCLUSION: Revision anterior open exposure to the lumbar and lumbosacral vertebral bodies can be performed safely, but is associated with an increased rate of early complications. Nonetheless, these complications are self-limited and highlight the importance of a multidisciplinary approach in maximizing the various surgical skills of spine (orthopedic and neurosurgical) and exposure (vascular and general) surgeons in reducing serious complications in revision anterior lumbar spinal surgery.