Regional coronary vasoconstriction after combined beta-adrenergic and calcium channel blockade in patients with coronary artery disease

The beta-adrenergic and calcium channel blocking drugs, which individually and combined have proven efficacious in the treatment of angina pectoris, appear to have opposing effects on coronary artery vasomotion. Previous studies have shown that beta-adrenergic blockade may potentiate and calcium channel blockade reverse coronary vasoconstriction during adrenergic cold stimulation in patients with coronary artery disease. To assess the coronary hemodynamic effects of combined drug therapy, thermodilution coronary sinus and great cardiac vein flow and mean arterial pressure were measured during serial cold pressor testing, both before and after 0.1 mg/kg of intravenous propranolol and again after the addition of 10 mg of sublingual nifedipine in 21 patients (9 without [group A1] and 12 with [group A2] greater than 50% narrowing of the left anterior descending coronary artery). In an additional 15 patients (6 patients without [group B1] and 9 with [group B2] left anterior descending artery stenosis), serial cold pressor testing was performed reversing the drug order. Despite significant increases in mean arterial pressure (p less than 0.01) during cold pressor testing, coronary sinus resistance responses after propranolol plus nifedipine were not statistically significant for any group. However, regional coronary resistance responses differed between patients with and without left anterior descending artery stenosis. In group A1, great cardiac vein resistance was unchanged after propranolol plus nifedipine. In group A2, great cardiac vein flow decreased significantly after propranolol plus nifedipine from 8 +/- 17 to -4 +/- 12% (p less than 0.01 versus control), and great cardiac vein resistance increased from 4 +/- 21 to 15 +/- 19% (p less than 0.01 versus control). A similar significant response was observed for groups B1 and B2. Regional coronary vasoconstriction during adrenergic stimulation after combined drug therapy was only observed in patients with significant left anterior descending artery stenosis. These data suggest that in some patients with severe coronary artery disease, combined beta-adrenergic and calcium channel blockade modified regional coronary responses to adrenergic stimulation with an inhomogeneous distribution of blood flow to potentially ischemic regions without affecting total coronary blood flow. These data also imply that an improvement in anginal symptoms after combined drug therapy may be due primarily to mechanisms that reduce myocardial oxygen demand rather than to improved myocardial oxygen supply.     

Demonstration of Cerebral Plasticity by Intra-Operative Neurophysiological Monitoring: Report of an Uncommon Case

Summary  It has been postulated long ago that “eloquent” areas shift their location in patients with arteriovenous malformations (AVM). Obviously the “motor region” in not located in the precentral gyrus in a patient with an AVM in the “motor region”.  We report on the case of a 15-year old boy with an AVM in the left sensorimotor cortex, in whom intra-operative mapping showed an inexcitability of the precentral gyrus, while stimulation of the cortex anterior to the primary motor cortex elicited motor responses. This indicates that motor function was translocated from the primary to the supplementary motor cortex. Surgery was performed under general anaesthesia. Neurophysiological monitoring was performed throughout surgery. The central sulcus was identified by phase reversal of the somatosensory evoked potentials. The motor cortex was mapped by direct high-frequency (500 Hz) monopolar anodal stimulation.  In the patient herein reported, stimulation of the “anatomically” defined primary motor cortex induced no motor response, as expected. Motor response was elicited only by stimulation of the cortex anterior to the precentral gyrus. There was no postoperative deterioration of motor function. These observations indicate that the precentral gyrus was functionally “useless”. The motor region was relocated into more rostral areas in the supplementary motor cortex. This translocation of function in the presence of an AVM indicates cerebral plasticity.     

Influence of Hemorrhagic Shock Followed by Crystalloid Resuscitation on Propofol: A Pharmacokinetic and Pharmacodynamic Analysis

Background: Previous work has demonstrated that ongoing hemorrhagic shock dramatically alters the distribution, clearance, and potency of propofol. Whether volume resuscitation after hemorrhagic shock restores drug behavior to baseline pharmacokinetics and pharmacodynamics remains unclear. This is particularly relevant because patients suffering from hemorrhagic shock are typically resuscitated before surgery. To investigate this, the authors studied the influence of an isobaric bleed followed by crystalloid resuscitation on the pharmacokinetics and pharmacodynamics of propofol in a swine model. The hypothesis was that hemorrhagic shock followed by resuscitation would not significantly alter the pharmacokinetics but would influence the pharmacodynamics of propofol.

Methods: After approval from the Animal Care Committee, 16 swine were randomly assigned to control and shock-resuscitation groups. Swine randomized to the shock-resuscitation group were bled to a mean arterial blood pressure of 40 mm Hg over a 20-min period and held there by further blood removal until 42 ml/kg of blood had been removed. Subsequently, animals were resuscitated with lactated Ringer's solution to maintain a mean arterial blood pressure of 70 mm Hg for 60 min. After resuscitation, propofol (750 [mu]g[middle dot]kg-1[middle dot]min-1) was infused for 10 min. The control group underwent a sham hemorrhage and resuscitation and received propofol at the same dose and approximate time as the shock-resuscitation group. Arterial samples (20 from each animal) were collected at frequent intervals until 180 min after the infusion began and were analyzed to determine drug concentrations. Pharmacokinetic parameters for each group were estimated using a three-compartment model. The electroencephalogram Bispectral Index Scale was used as a measure of drug effect. Pharmacodynamics were characterized using a sigmoid inhibitory maximal effect model.

Results: The raw data demonstrated minimal differences in the mean plasma propofol concentrations between groups. The compartment analysis revealed some subtle differences between groups in the central and slow equilibrating volumes, but the differences were not significant. Hemorrhagic shock followed by resuscitation shifted the concentration effect relationship to the left, demonstrating a 1.5-fold decrease in the effect-site concentration required to achieve 50% of the maximal effect in the Bispectral Index Scale.     

Age-related total gray matter and white matter changes in normal adult brain. Part I: volumetric MR imaging analysis

BACKGROUND AND PURPOSE: A technique of segmenting total gray matter (GM) and total white matter (WM) in human brain is now available. We investigated the effects of age and sex on total fractional GM (%GM) and total fractional WM (%WM) volumes by using volumetric MR imaging in healthy adults. METHODS: Fifty-four healthy volunteers (22 men, 32 women) aged 20-86 years underwent dual-echo fast spin-echo MR imaging. Total GM, total WM, and intracranial space volumes were segmented by using MR image-based computerized semiautomated software. Volumes were normalized as a percentage of intracranial volume (%GM and %WM) to adjust for variations in head size. Age and sex effects were then assessed. RESULTS: Both %GM and %WM in the intracranial space were significantly less in older subjects (> or =50 years) than in younger subjects (<50 years) (P <.0001 and P =.02, respectively). Consistently, %GM decreased linearly with age, beginning in the youngest subjects. %WM decreased in a quadratic fashion, with a greater rate beginning only in adult midlife. Although larger GM volumes were observed in men before adjustments for cranium size, no significant differences in %GM or %WM were observed between the sexes. CONCLUSION: GM volume loss appears to be a constant, linear function of age throughout adult life, whereas WM volume loss seems to be delayed until middle adult life. Both appear to be independent of sex. Quantitative analysis of %GM and %WM volumes can improve our understanding of brain atrophy due to normal aging; this knowledge may be valuable in distinguishing atrophy of disease patterns from characteristics of the normal aging process.     

Zwölf Jahre laparoskopische Cholezystektomie

We studied developments in indication, operation time, conversion rate, morbidity, and mortality from the beginning of laparoscopic cholecystectomy. Between 1990 and 2002 we prospectively evaluated 4498 patients undergoing cholecystectomy (CE), of whom 79% were treated laparoscopically (lap). In 6.6%, the procedure had to be converted from laparoscopic to open cholecystectomy (con), and 14% were performed open from the beginning (open). During the above time period, the rate of open CE decreased steadily (49% in 1990 to 7.2% in 2002). The average operation time of lap CE remained constant with an average of 74 min (range 20-330). The conversion rate decreased in spite of broader indication for lap CE in even more complicated gallstone diseases, from an initial 9.4% to 2.5%. Among intraoperative complications in lap and con, bile duct lesions remained constant with 5/3856 (0.1%), bleeding which led to conversion decreased from 1.9% to 0.3%, and the rate of gall bladder perforation increased from 12% to 20.5%. Thirty-day morbidity was 2% in lap CE, 5% in con, and 11.5% in open. The mortality was 0% in lap, 0.7% in con, and 1% in open. CONCLUSION: Since the introduction of laparoscopic cholecystectomy the indication for this minimal-invasive operation steadily increased, the conversion-rate decreased and the complication-rate could be held low. Even with fast laparoscopic experience 7% of all cholecystectomies are technically difficult and remain to be carried out primarily in an open technique. The laparoscopic cholecystectomy has become the gold standard in the therapy of gallstone disease.     

Palliative operation for the treatment of alveolar echinococcosis

Background  The World Health Organization guidelines recommend radical hepatic resection for definite treatment of alveolar echinococcosis (AE), because it can cure the patient. However, parasitic masses are not entirely removable in about 70% of patients. Even so, palliative resections are carried out, although cure cannot be achieved. As conservative treatment has improved, the role of palliative surgical procedures has to be redefined. Methods  Critical appraisal of published reports on palliative resections for AE and estimation of the level of evidence and grade of recommendation. Results  Prospective randomized trials comparing palliative resections, radical resections, and conservative treatment are lacking. Most papers analyzed case series retrospectively. The number of palliative operations is significant. In the past, palliative resections were recommended in order to enhance anthelminthic drug efficacy but advances in conservative and interventional treatment improved the prognosis of AE. Prolonged survival by systematic palliative resections is not evident. However, palliative surgery is an option to treat persistent bacterial infection, fistulas, and obstructing or compressing masses. The indication is based on individual considerations and decisions. Conclusion  Curative surgery for AE is feasible if parasitic tissue is entirely removable. The benefit of palliative resections is uncertain because long-term results of conservative treatment are favorable. Palliative surgery is an option for complications not being manageable otherwise. Study aim Evaluation of the role of palliative operation for AE.     

Open vertebral cement augmentation combined with lumbar decompression for the operative management of thoracolumbar stenosis secondary to osteoporotic burst fractures

Osteoporotic burst fractures with neurologic symptoms are typically treated with neural decompression and multilevel instrumented fusion. These large surgical interventions are challenging because of patients' advanced ages, medical co-morbidities, and poor fixation secondary to osteoporosis. The purpose of this retrospective clinical study was to describe a novel technique for the treatment of osteoporotic burst fractures and symptomatic spinal stenosis via a limited thoracolumbar decompression with open cement augmentation [vertebroplasty (VP) or kyphoplasty (KP)]. Indications for decompression and cement augmentation were intractable pain at the level of a known osteoporotic burst fracture with symptoms of spinal stenosis. As such, 25 patients (mean age, 76.1 years) with low-energy, osteoporotic, thoracolumbar burst fractures (7 males, 18 females; 39 fractures) were included. In all cases, laminectomy of the stenotic level(s) was followed by vertebral cement augmentation (9 VP; 16 KP). When a spondylolisthesis at the decompressed level was present, instrumentation was applied across the listhetic level (n = 9). Clinical outcome (1 = poor to 4 = excellent) was assessed on last clinical follow-up (mean, 44.8 wks). In addition, a modified MacNab's grading criteria was used to objectively assess patient outcomes postoperatively. Radiographic analysis of sagittal contour was assessed preoperatively, immediately postoperatively, and at final follow-up. The average time from onset of symptoms to intervention was 19 weeks (range, 0.3-94 wks). A mean of 1.6 fractures/patient was augmented (range, 1-3 fractures) and 2.8 levels were decompressed (range, 1-6 levels). No statistical difference in anatomic distribution or number of fractures between the VP and KP groups or in the instrumented versus noninstrumented patients was noted (P > 0.05). An overall subjective outcome score of 3.4 was noted. Twenty of 25 patients were graded as excellent/good according to the modified MacNab's criteria. The choice of augmentation procedure or use of instrumentation did not predict outcome (P = 0.08). Overall, 1.7 degrees of sagittal correction was obtained at final follow-up. One patient was noted to have progressive kyphosis after KP. The use of a limited-posterior decompression and open cement augmentation via VP or KP is a safe treatment option for patients who have osteoporotic burst fractures and who are incapacitated from fracture pain and concomitant stenosis. After thoracolumbar decompression, open VP/KP provides direct visualization of the posterior vertebral body wall, allowing for safe cement augmentation of burst fractures, stabilizing the spine, and obviating the need for extensive spinal reconstruction. Although clinically successful, this technique warrants careful patient selection.     

A grading system for nasal dorsal deformities

There is no uniform grading system for nasal dorsal deformities currently in general use among surgeons who perform rhinoplasty. Given the popularity of this procedure among both the general public and surgeons, it is time that there was a uniform system describing dorsal deformities. Such a system has value in the education of students of rhinology and cosmetic nasal surgery. We have developed one such system, and applied it to 100 cases. In all cases it accurately describes the major pathological conditions of the dorsum, if present, as noted on physical examination. We have found application of this system to be facile.     

The influence of hemorrhagic shock on etomidate: a pharmacokinetic and pharmacodynamic analysis

We studied the influence of hemorrhagic shock on the pharmacology of etomidate in swine. Sixteen swine were randomly assigned to control and shock groups. The shock group was bled to a mean arterial blood pressure of 50 mm Hg and held there until 30 mL/kg blood was removed. Etomidate 300 micro g x kg(-1) x min(-1) was infused for 10 min to both groups. Fifteen arterial samples were collected until 180 min after the infusion began to determine drug concentration. Pharmacokinetic variables for each group were estimated by using a three-compartment model. The bispectral index scale was used as a measure of drug effect. The pharmacodynamics were characterized by using a sigmoid inhibitory maximal effect model. The raw data revealed a 25% increase in the plasma etomidate concentration at the end of the 10-min infusion which resolved after termination of the infusion in the shock group. The pharmacokinetic analysis revealed subtle changes in the variable estimates between groups. The etomidate infusion produced a similar Bispectral Index Scale change in both groups. These results demonstrated that, unlike the influence of hemorrhagic shock on other sedative hypnotics and opioids, moderate hemorrhagic shock produced minimal changes in the pharmacokinetics and no change in the pharmacodynamics of etomidate. IMPLICATIONS: Hemorrhagic shock produced minimal changes in the pharmacokinetics and no change in the pharmacodynamics of etomidate in swine. These results suggest that, unlike other sedative hypnotics and opioids, minimal adjustment in the dose of etomidate is required to achieve the same drug effect during hemorrhagic shock.