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  • Author or Editor: Thoralf M. Sundt Jr x
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Thoralf M. Sundt Jr.

✓ The author reviews a form of management for patients deteriorating preoperatively or postoperatively from apparent ischemia attributed to progressive vasospasm after a subarachnoid hemorrhage. The clinical picture and relative frequency of this complication are considered in relationship to the status (grade) of the patient, location of the aneurysm, and ultimate neurological recovery. Experience suggests that the drug regimen reported is useful when instituted early after the onset of symptoms and is safe with proper monitoring techniques. The data do not justify early operative intervention after a subarachnoid hemorrhage, operation when there is angiographic evidence of severe spasm, or expectation of a dramatic effect in patients with a profound deficit or a fixed deficit several hours old.

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Thoralf M. Sundt Jr.

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Thoralf M. Sundt Jr.

✓ On June 30, Mrs. Jean Lawe will step down as Managing Editor of the Journal of Neurosurgery. She has worked on the Journal since 1965, when Dr. Louise Eisenhardt retired as the first Editor. Since that time the Journal has grown in size and circulation, and production has become fully computerized. In her valedictory, Mrs. Lawe summarizes her years with the Journal and her approach to scientific editing.

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Thoralf M. Sundt III and Thoralf M. Sundt Jr.

✓ Experience in cardiovascular and peripheral vascular surgery with saphenous vein bypass conduits is reviewed. It is clear that meticulous technique and graft preparation are crucial to short-term and long-term patency. The risk of early thrombosis is related to damage to the graft 's native intima, graft flow, and coagulability of the patient 's blood. Attention to atraumatic harvesting techniques and perfection of anastomoses are crucial to minimizing intimal damage. Graft inflow and outflow are fundamental principles. The use of vitamin K antagonists and platelet inhibitors may improve graft survival. Subacute occlusion is related to structural alterations in the grafts themselves. These include intimal hyperplasia and medial fibrosis as the grafts become “arterialized,” valve fibrosis, aneurysmal dilatation, clamp stenosis, and suture stenosis. Long-term patency is threatened primarily by atherosclerosis in the graft itself. There is some evidence that care in vein harvesting and implantation as well as the use of anticoagulant agents affect the development of this complication.

A technique for graft preparation is presented that is based on the experience of the authors in harvesting grafts for both cerebral and coronary bypass conduits.

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Thoralf M. Sundt Jr. and George Kees Jr.

✓ The authors have designed a miniclip and a microclip for occlusion of small perforating vessels deep in the operative wound. These clips are intended for permanent occlusion but may be used for temporary hemostasis.

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Thomas J. Rosenbaum and Thoralf M. Sundt Jr.

✓ The sequential hematological and endothelial responses in the postoperative period after end-to-side arterial anastomosis in 1- to 1.3-mm vessels were assessed by scanning electron microscopy. Two minutes after restoration of flow, an amorphous coating covered the vessel lumen around the suture line, and oozing of blood from the suture line ceased. Within 15 minutes, a partially occluding thrombus was present, which was maximal at the anastomotic bifurcation point. The thrombus underwent partial lysis or embolization within 30 minutes, and gross intraluminal thrombi did not recur. The initial thrombi that formed within 2 minutes were composed of platelets and erythrocytes in a loose reticular fibrin network, but the intraluminal thrombi present at the branch point 15 minutes after flow restoration appeared to be composed solely of platelets. Thrombi that did not undergo complete dissolution had a loss of distinct cellular elements at later time intervals. The fibrin-platelet matrix coating the lumen remained unchanged during the initial 24 hours. When examined at 9 days, normal endothelium was present throughout the vessel with the exception of the suture line, which remained covered by a smooth coagulum. This sequence of events suggests that if surgical manipulation is to result in complete occlusion of the anastomosis, it will likely occur in the initial 30 minutes after resumption of blood flow.

Anticoagulant regimens were evaluated. Pretreatment with aspirin and intraoperative heparin irrigation of the vessel lumen were not beneficial in altering the quantity of thrombus. All systemic heparin regimes tested resulted in a quantitative decrease of thrombotic material. Five minutes of intravenous heparin therapy after resumption of blood flow was as effective as long-term heparin in decreasing the transient intraluminal thrombotic response.

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Dudley H. Davis and Thoralf M. Sundt Jr.

✓ The relationship among cerebral blood flow (CBF), blood volume, cardiac output (CO), and mean arterial blood pressure (MABP) at varying levels of arterial CO2 tensions (PaCO2) were studied in 70 normal cats. The CBF was measured from the clearance curve of xenon−133 and CO with a thermal dilution catheter placed in the pulmonary artery. The CBF, CO, and MABP values varied appropriately with changes in PaCO2, confirming the reliability of the preparations and the presence of normal autoregulatory responses. Moderate hypovolemia that did not change MABP did, nevertheless, significantly decrease CO and CBF. In an effort to determine if this decrease in CO and CBF were coupled responses, the effects of beta stimulation, hypervolemia, and alpha and beta blockade were investigated. Propranolol, in a dosage insufficient to change MABP, decreased both CO and CBF. This agent abolished the CO response to elevations in PaCO2 but not the CBF response, making it unlikely that this CBF reduction resulted from impaired cerebral autoregulation. Isoproterenol, which, in contrast to propranolol, does not cross the normal blood-brain barrier, alone or in combination with phenoxybenzamine, produced a 38% and 72% increase in CO, respectively, without a change in CBF. Alpha blockade (no major change in CO) and beta blockade (major decrease in CO) did not significantly effect cerebral autoregulation to changes in MABP from angiotensin. The ability of the brain to resist increases in MABP and CO and maintain normal CBF is explained by normal cerebral autoregulation. However, its vulnerability to modest decreases in blood volume, which cannot be attributed to variations in perfusion pressure, is unexplained but obviously has important therapeutic implications. This may be related to reduction in CO, changes in autonomic activity, or a decrease in the size of the perfused capillary bed.

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Thoralf M. Sundt Jr. and David G. Piepgras

✓ Arteriovenous malformations (AVM's) of lateral and sigmoid sinuses are acquired lesions evolving from a previously thrombosed dural sinus. Their natural history is usually that of gradual progression and hence surgery is frequently necessary. The preferred surgical treatment is complete excision coupled with packing of the sigmoid sinus. The operative approach is illustrated and discussed in detail. Results and complications are reviewed in 27 patients whose symptomatology had progressed under conservative management; 22 of these cases harbored primary lesions and five had recurrences. There were 22 excellent, one good, and two poor results (both of the latter from blindness that preceded surgery). There were two deaths, both in patients previously operated on with incomplete removal or obliteration of the AVM by attempted embolization.