Preperitoneal suprahepatic pacemaker generator placement in the pediatric population

We have used a preperitoneal suprahepatic location for pacemaker generator placement in pediatric patients requiring permanent pacemakers with epicardial leads. The technique is rapid, simple, and safe, and cosmesis is excellent, making this approach particularly advantageous in the younger infant and neonate.

Pericardial substitute and emergency resternotomy: life-saving combination

Retrosternal adhesions prolong operating time during reoperative pediatric cardiac surgery and promote myocardial injury. A case is presented in which a polytetrafluoroethylene pericardial substitute facilitated a rapid, life-saving emergency resternotomy in a moribund patient.

Simultaneous manipulation of the nitric oxide and prostanoid pathways reduces myocardial reperfusion injury

The effects of aspirin and L-arginine (biological precursor of nitric oxide) on the production of hydroxyl radicals, cyclic guanosine monophosphate levels, vascular tone, and the recovery of the ischemic myocardium were investigated in isolated rat hearts subjected to ischemia and reperfusion. After 30 minutes of perfusion, hearts were arrested with St. Thomas' Hospital cardioplegic solution, global ischemia was induced at 37 degrees C for 45 minutes, and the hearts were then reperfused at 37 degrees C for 30 minutes. The percent change in recovery of pulse pressure and maximal change of this pressure with time were better in the group perfused with Krebs-Henseleit solution containing aspirin plus L-arginine (17% +/- 23%, p = 0.001, and 10% +/- 25%, p = 0.002, respectively) compared with these values in the control group perfused with Krebs-Henseleit solution alone (-7% +/- 14% and -11% +/- 16%, respectively). Coronary vascular resistance before and after ischemia were lower in the aspirin plus L-arginine group (0.19 +/- 0.03 dynes.sec/cm5, p = 0.001, and 0.23 +/- 0.04 dynes.sec/cm5, p = 0.01, respectively) compared with those of the control group (0.24 +/- 0.02 and 0.28 +/- 0.07 dynes.sec/cm5, respectively). Cyclic guanosine monophosphate levels increased from 22.5 +/- 6 pmol/100 mg of tissue in the control group to 37.1 +/- 8.9 pmol/100 mg (p = 0.002) in the aspirin plus L-arginine group. Adding N omega-nitro-L-arginine methyl ester to the perfusion medium caused a deterioration in pulse pressure and maximal change of this pressure with time, a decrease in cyclic guanosine monophosphate, and a rise in coronary vascular resistance. The addition of L-arginine to the solution in the Krebs-Henseleit solution plus aspirin group increased the production of hydroxyl radicals from 0.32 +/- 0.18 nmol/gm per 3 minutes to 0.75 +/- 0.33 nmol/gm per 3 minutes (p = 0.03). Despite the association of nitric oxide with increased hydroxyl radical production, it appears that nitric oxide has an overall beneficial effect on the recovery of the ischemic myocardium. The synergism between aspirin and arginine may be caused in part by the scavenging of hydroxyl radicals. Alternatively, by inhibiting the prostaglandin pathway, aspirin may reduce the generation of superoxide anion, a free radical that inactivates nitric oxide. The prolonged half-life of nitric oxide may explain the increased levels of cyclic guanosine monophosphate seen in the group perfused with Krebs-Henseleit solution plus aspirin plus L-arginine. Aspirin and L-arginine, both readily available, may be useful adjuncts to clinical cardioplegia strategy.

Modified surgical palliation for a rare type of L-transposition with aortic atresia

L-Transposition of the great arteries with aortic atresia without an outlet chamber is a rare congenital heart defect. We used a modified Norwood procedure incorporating a type of direct coronary transfer for successful palliation of this lesion in a neonate.

Left thoracotomy for emergent repair of ventricular rupture during mitral valve replacement

Ventricular rupture is a dreaded complication of mitral valve replacement. We present a case of ventricular rupture that occurred during mitral valve replacement and was successfully repaired through a left thoracotomy approach.

Balloon occlusion scintigraphy of aortopulmonary collaterals

We evaluated two children with pulmonary atresia for coil embolization of aortopulmonary collateral vessels after placement of palliative aortopulmonary shunts. To determine vessel distribution and lung perfusion prior to collateral embolization, perfusion scintigraphy with technetium 99m-labeled macroaggregated albumin assessed pulmonary blood flow before and after balloon wedge catheter occlusion of the collaterals. In the first patient we found no perfusion defect during collateral occlusion, and we proceeded with embolization. In the second child, perfusion scintigraphy during occlusion of the collateral vessels demonstrated a filling defect, and embolization was not performed, thus avoiding the creation of a potential perfusion defect in this patient. Assessing the physiologic significance of aortopulmonary collateral vessels by utilizing temporary balloon occlusion of the collateral vessels and concurrent perfusion scintigraphy as an adjunct to selective angiography can provide a significant contribution to the safety and accuracy of coil embolization.

Partial sensory trigeminal rhizotomy at the pons for trigeminal neuralgia

Microvascular decompression is preferred among open procedures for the treatment of trigeminal neuralgia. However, in some cases the decompression cannot be performed, either because no significant vascular compression of the trigeminal nerve is found at surgery or because a patient's vascular anatomy makes it unsafe. Partial sensory rhizotomy is a commonly used alternative in these instances. The outcome after partial sensory rhizotomy was reviewed retrospectively in 83 patients with an average follow-up period of 72 months. Sixty-four (77%) of these patients had no evidence of vascular contact at operation. The remaining 19 patients (23%) had vascular structures in proximity to the trigeminal nerve but still underwent partial sensory rhizotomy in place of or in addition to microvascular decompression either because the offending vessel could not be moved adequately (11 cases) or because the vascular contact was considered insignificant (eight cases). Outcome was classified as: excellent if there was no trigeminal neuralgia postoperatively; good if pain persisted or recurred but was less severe than preoperatively; and poor if persistent or recurrent pain was equal to or greater than the preoperative pain in severity and was refractory to medication, or was severe enough to require additional surgery. The outcome was excellent in 40 patients (48%), good in 18 (22%), and poor in 25 (30%); follow-up durations were similar for the three outcome categories. The failure rate was 17% for the 1st year and averaged 2.6% each year thereafter. Two variables were predictive of a poor outcome: prior surgery and lack of preoperative involvement of the third trigeminal division. Major complications occurred in 4% of cases and minor complications in 11%. The authors conclude that partial sensory rhizotomy is a safe and effective alternative to microvascular decompression when neurovascular compression is not identified at operation or when microvascular decompression cannot be performed for technical reasons.

Solitary eosinophilic granuloma invading the clivus of an adult: case report

A 41-year-old white man with facial pain and diplopia was found to have an invasive lesion of the clivus. The final pathological diagnosis was eosinophilic granuloma. The patient's symptoms resolved completely after transsphenoidal resection of the lesion. The pathological and radiological diagnosis and the treatment of solitary eosinophilic granulomas are discussed.

Dorsal third ventricular cyst: an entity distinct from holoprosencephaly

The treatment and subsequent developmental progress of six children with dorsal third ventricular cysts are described. This cystic malformation has a radiological appearance which is superficially similar to that of the dorsal cyst of alobar holoprosencephaly, especially when the third ventricular cyst is large. Indeed, previous reports have identified this abnormality as a form of holoprosencephaly. However, careful study reveals that the dorsal third ventricular cyst is a distinct entity both developmentally and clinically. The six patients in this series were effectively treated with shunts, and their subsequent developmental progress was assessed by means of the Prescreening Developmental Questionnaire-Revised as well as the Bayley Scales of Infant Development. The nomenclature and differences between this entity and the holoprosencephalies are reviewed. The authors conclude that dorsal third ventricular cysts have a developmental and clinical course more similar to that of arachnoid cysts than to that of the holoprosencephalies.

Mechanism of spreading depression: a review of recent findings and a hypothesis

Spreading depression of Leão (SD) can be provoked by numerous nonspecific mechanical, electrical, and chemical stimuli. A similar, if not identical, phenomenon can be provoked by hypoxia. SD is characterized by drastic depolarization of neurons, severe reduction of membrane resistance, and redistribution of ions across cell membranes. Glial cells also depolarize but retain membrane resistance. Tetraethylammonium hastens the onset of hypoxic SD but reduces the sustained potential shift and K+ outflow from cells; 4-aminopyridine also accelerates SD but has no effect on the voltage shift. N-Methyl-D-aspartate receptor antagonists delay the onset of SD, while nickel and cobalt reduce the amplitude of SD-related redistribution of Ca2+. Yet, no specific blocker of SD has been found. Microdialysis of high-K+ solution in hippocampal CA1 region induces recurrent waves of SD propagating semi-independently in adjacent tissue layers, and a prolonged unstable depressed state that has not previously been described. Neither the release of K+ ions nor of glutamate is the unique agent of SD propagation. On the basis of recent findings we propose a hypothetical sequence of events that reconcile many of the previously seemingly paradoxical observations.

Suppression of presynaptic calcium currents by hypoxia in hippocampal tissue slices

We tested the hypothesis that suppression of inward calcium current in presynaptic terminals is the cause of failure of synaptic transmission early during cerebral hypoxia. Postsynaptic responses in CA1 zone of hippocampal tissue slices were blocked either by the combined administration of 6,7-dinitroquinoxaline-2,3-dione (DNQX) and 3-((+-)-2-carboxypiperazine-4-yl)-propyl-1-phosphonic acid (CPP) or by lowering extracellular calcium concentration ([Ca2+]o). Repetitive orthodromic activation of central neurons caused transient decrease of [Ca2+]o (measured by ion selective microelectrodes) in neuropil, attributable to influx of Ca2+ in presynaptic terminals. Presynaptic [Ca2+]o responses were rapidly and reversibly suppressed when oxygen was withdrawn from hippocampal tissue slices. The 'resting' baseline level of [Ca2+]o declined at first gradually, then precipitously as in spreading depression (SD). Presynaptic volleys during high frequency train stimulation were also depressed somewhat before SD began. We conclude that (1) presynaptic Ca2+ currents fail during hypoxia, perhaps because 'resting' intracellular free Ca2+ activity is increased and, in part, also because of partial failure of presynaptic impulse conduction; (2) the influx of Ca2+ into brain cells in hypoxic spreading depression is not mediated by glutamate/aspartate dependent channels.

Deafferentation syndrome in the rat: effects of sex, age, and lesion type

A deafferentation syndrome can be produced in Sprague-Dawley rats following dorsal root sections. The behavior may be objective evidence of dysesthesias, thus serving as an experimental model to study chronic dysesthesias caused by deafferentation in humans. This article examines the effects of sex, age, and lesion type on the expression of the deafferentation syndrome in Sprague-Dawley rats. No significant differences were found in the expression of the deafferentation syndrome with respect to age and weight in male rats within the ranges studied. Sex and lesion type did alter the expression of the syndrome.

Nuclear magnetic resonance imaging of the palliative operation for hypoplastic left heart syndrome

Electrocardiographic-gated nuclear magnetic resonance (NMR) imaging has been shown to be effective for the evaluation of congenital heart disease, particularly in supracardiac regions. This study evaluated the postoperative status after a stage I palliative operation (Norwood procedure) for hypoplastic left heart syndrome. The NMR images from three patients were compared with those of angiography and depicted all components of the reconstructed supracardiac and intracardiac anatomy after this operation. Nonobstructive anastomosis of the main pulmonary artery to the proximal aorta was clearly demonstrated in each patient. The caliber of the central or branch pulmonary artery, patency and caliber of the systemic to pulmonary artery shunt and the size of the atrial communication were also depicted in each patient and these findings corresponded with angiographic results. The results suggest that NMR imaging is effective for assessing the results of initial palliative surgery for hypoplastic left heart syndrome, which seems to be important for managing patients before subsequent definitive surgery.

Calcium, magnesium, and long-term recovery from hypoxia in hippocampal tissue slices

Ortho- and antidromic responses recovered and remained robust for 5 h in slices exposed to transient hypoxia in low calcium, while responses remained depressed in slices made hypoxic in normal calcium. Elevating magnesium in addition to reducing calcium did not improve recovery compared to reducing calcium alone. Spreading depression-like hypoxic depolarization occurred earlier in low calcium than in control fluid. We conclude that loss of function was triggered by calcium uptake by neurons and not by cell swelling, and that activation of NMDA receptors probably played no part.

Hemangiopericytoma of the sciatic nerve. Case report

The authors report the case of a hemangiopericytoma arising in a sciatic nerve. It was found to be invasive within the epineurium but sparing surrounding tissues. Adequate resection required sacrifice of the nerve. Hemangiopericytomas can be added to the short list of mesodermal peripheral-nerve tumors.

Porcine heparin increases postoperative bleeding in cardiopulmonary bypass patients

One hundred thirteen patients undergoing cardiopulmonary bypass were randomly assigned to receive either bovine or porcine heparin. Heparin was infused at 4.5 mg/kg during bypass and administered at the lesser of 70 units/kg or 5000 units/dose at 12-hour intervals postoperatively. Platelet counts decreased to 45% of preoperative levels during the first 3 days postoperatively (porcine, 44 +/- 13%, n = 50; bovine, 46 +/- 15%), but returned to preoperative levels by the seventh postoperative day. The average blood loss in the porcine heparin group significantly exceeded that of the bovine heparin group (porcine, 1350.7 +/- 727.8 ml; bovine, 1059.6 +/- 381.0 ml; p less than .01). Consequently, the platelet transfusion requirement was greater in the porcine heparin group (porcine, 1.7 +/- 3.9 units; bovine, 0.5 +/- 1.7 units; p less than .05); however, blood and blood component (with the exception of platelets) administration was not significantly different between the two groups. The four patients taking anticoagulants or antiinflammatory agents in the porcine group required a mean of 8.5 units of red blood cells (RBC) plus supplemental platelets. The seven such patients in the bovine group received a mean of 3.0 units of RBC and no platelets. Thus, the use of porcine heparin resulted in a generalized increase in postoperative bleeding with increased management problems in patients undergoing cardiopulmonary bypass.

Omental pedicle grafting in the treatment of postcardiotomy sternotomy infection

Postcardiotomy sternal infection occurred in 20 (2%) of 1007 patients undergoing cardiac surgery between September 1985 and December 1987, a 10-fold increase over the preceding 33 months (4 [0.24%] of 1627 patients). Cultures were sterile in 5 patients and yielded staphylococci in 12 and a variety of bowel organisms in 3. The cause for the increased occurrence of sternal wound infection is unclear after multivariate analysis, although infections have precipitously dropped subsequent to changing to cefuroxime sodium antibiotic prophylaxis. Treatment has evolved to appropriate antibiotics and early débridement of involved sternum and cartilage. Rewiring the sternum is not attempted. If gross purulence is not present, primary closure is accomplished using muscle flaps (2 patients) or omental pedicle grafts (17 patients). In the presence of gross purulence, the wound is packed open for 5 days and then closed in the above fashion. Two patients required skin grafts for primary closure. The omental pedicle flap is preferred due to simplicity and improved coverage of the sternal defect inferiorly. Nineteen patients healed primarily. A superficial wound infection was drained in 1 patient. Midline incisional hernias developed in 3 muscular patients. Omentum is now harvested through a left subcostal incision. Hospital stay was under 2 weeks in 13 patients. One death occurred due to multisystem failure prior to completion of wound closure. In our experience, early sternal débridement and omental pedicle grafting with primary closure is appropriate therapy for postcardiotomy sternotomy infections. The presence of gross purulence may require 5 days of open packing prior to omental grafting. No significant complications occurred, and mortality was low. A left subcostal incision for omental harvesting is utilized to avoid the occurrence of delayed incisional hernias.

Surgical management of traumatic disruption of the descending aorta

During an 11 1/2-year period, 20 consecutive patients presenting with a traumatic disruption of the proximal descending aorta underwent an emergency operative repair. The mean age was 26 years (range 15 to 62), and 13 (65%) were male. Associated injuries were frequent and required additional major operative procedures in half of the cases. Two patients died as a result of associated intracranial injuries, for a hospital survival of 90%. The operative repair was accomplished by graft replacement of the involved segment of the aorta in all but one patient who underwent a primary repair. Simple aortic crossclamping was used in 8 patients (40%) and heparinless femoral-femoral venoarterial bypass in 12 patients (60%). Neither renal failure nor paraplegia in any of the patients. Four patients required thoracic reoperations. These results indicate that an aggressive multidisciplinary surgical approach can produce favorable results in patients with traumatic descending aortic injuries.

Internal banding for palliation of truncus arteriosus in the neonate

A method for surgically limiting pulmonary blood flow in the critically ill neonate with truncus arteriosus is described. Two recent cases utilizing this technique are presented. Comparisons are made between this and other palliative surgical procedures used in truncus arteriosus.

A new insulated caudalis nucleus DREZ electrode. Technical note

A new insulated radiofrequency electrode for making nucleus caudalis dorsal root entry zone lesions reduces the incidence of ataxia.