The role of full-thickness scalp resection for management of primary scalp melanoma

BACKGROUND

Scalp melanoma is aggressive and has a proclivity for regional metastasis. We hypothesize that subperiosteal scalp melanoma resection reduces in-transit/satellite recurrence, when compared with subgaleal resection.

METHODS

We identified patients with intermediate to deep, primary scalp melanoma referred to head/neck surgery over an 8-year period. Patients were compared based on scalp resection depth, including subperiosteal (resection to the level of calvarium) and subgaleal (resection including skin, subcutaneous tissue, and galea). The dependent variables were in-transit/satellite recurrence and time to in-transit/satellite recurrence.

RESULTS

Among 48 identified patients, the in-transit/satellite recurrence rate was 16.7%. Subgaleal resection patients had higher in-transit/satellite recurrence rates than subperiosteal resection patients (24.0% vs. 8.7%, P=0.155). Among node-negative patients, subgaleal resection had significantly higher in-transit/satellite metastasis rates when compared with subperiosteal resection (26.3% vs. 0%, P=0.047).

CONCLUSION

For node-negative, primary scalp melanoma, subperiosteal resection significantly decreases in-transit/satellite recurrence when compared with subgaleal resection. Given our small sample size, further studies are necessary to confirm these results.

Sentinel lymph node biopsy is accurate and prognostic in head and neck melanoma

BACKGROUND

Sentinel lymph node biopsy (SLNB) has emerged as a widely used staging procedure for cutaneous melanoma. However, debate remains around the accuracy and prognostic implications of SLNB for cutaneous melanoma arising in the head and neck, as previous reports have demonstrated inferior results to those in nonhead and neck regions. Through the largest single-institution series of head and neck melanoma patients, the authors set out to demonstrate that SLNB accuracy and prognostic value in the head and neck region are comparable to other sites.

METHODS

A prospectively collected database was queried for cutaneous head and neck melanoma patients who underwent SLNB at the University of Michigan between 1997 and 2007. Primary endpoints included SLNB result, time to recurrence, site of recurrence, and date and cause of death. Multivariate models were constructed for analyses.

RESULTS

Three hundred fifty-three patients were identified. A sentinel lymph node was identified in 352 of 353 patients (99.7%). Sixty-nine of the 353 (19.6%) patients had a positive SLNB. Seventeen of 68 patients (25%) undergoing completion lymphadenectomy after a positive SLNB result had at least 1 additional positive nonsentinel lymph node. Patients with local control and a negative SLNB failed regionally in 4.2% of cases. Multivariate analysis revealed positive SLNB status to be the most prognostic clinicopathologic predictor of poor outcome; hazard ratio was 4.23 for SLNB status and recurrence-free survival (P < .0001) and 3.33 for overall survival (P < .0001).

CONCLUSIONS

SLNB is accurate and its results are of prognostic importance for head and neck melanoma patients.

Features predicting sentinel lymph node positivity in Merkel cell carcinoma

PURPOSE

Merkel cell carcinoma (MCC) is a relatively rare, potentially aggressive cutaneous malignancy. We examined the clinical and histologic features of primary MCC that may correlate with the probability of a positive sentinel lymph node (SLN).

METHODS

Ninety-five patients with MCC who underwent SLN biopsy at the University of Michigan were identified. SLN biopsy was performed on 97 primary tumors, and an SLN was identified in 93 instances. These were reviewed for clinical and histologic features and associated SLN positivity. Univariate associations between these characteristics and a positive SLN were tested for by using either the χ(2) or the Fisher's exact test. A backward elimination algorithm was used to help create a best multiple variable model to explain a positive SLN.

RESULTS

SLN positivity was significantly associated with the clinical size of the lesion, greatest horizontal histologic dimension, tumor thickness, mitotic rate, and histologic growth pattern. Two competing multivariate models were generated to predict a positive SLN. The histologic growth pattern was present in both models and combined with either tumor thickness or mitotic rate.

CONCLUSION

Increasing clinical size, increasing tumor thickness, increasing mitotic rate, and infiltrative tumor growth pattern were significantly associated with a greater likelihood of a positive SLN. By using the growth pattern and tumor thickness model, no subgroup of patients was predicted to have a lower than 15% to 20% likelihood of a positive SLN. This suggests that all patients presenting with MCC without clinical evidence of regional lymph node disease should be considered for SLN biopsy.

Surgical management of primary disease

Despite advancements in the treatment of melanoma, surgical management remains the cornerstone for treatment and long-term survival. The authors present their surgical approach to the patient with melanoma including evaluation, treatment, and reconstruction. In addition, management of melanoma occurring in difficult anatomic areas and in special patient populations is reviewed.

Is there a benefit to sentinel lymph node biopsy in patients with T4 melanoma?

BACKGROUND

Controversy exists as to whether patients with thick (Breslow depth>4 mm), clinically lymph node-negative melanoma require sentinel lymph node (SLN) biopsy. The authors examined the impact of SLN biopsy on prognosis and outcome in this patient population.

METHODS

A review of the authors' institutional review board-approved melanoma database identified 293 patients with T4 melanoma who underwent surgical excision between 1998 and 2007. Patient demographics, histologic features, and outcome were recorded and analyzed.

RESULTS

Of 227 T4 patients who had an SLN biopsy, 107 (47%) were positive. The strongest predictors of a positive SLN included angiolymphatic invasion, satellitosis, or ulceration of the primary tumor. Patients with a T4 melanoma and a negative SLN had a significantly better 5-year distant disease-free survival (DDFS) (85.3% vs 47.8%; P<.0001) and overall survival (OS) (80% vs 47%; P<.0001) compared with those with metastases to the SLN. For SLN-positive patients, only angiolymphatic invasion was a significant predictor of DDFS, with a hazard ratio of 2.29 (P=.007). Ulceration was not significant when examining SLN-positive patients but the most significant factor among SLN-negative patients, with a hazard ratio of 5.78 (P=.02). Increasing Breslow thickness and mitotic rate were also significantly associated with poorer outcome. Patients without ulceration or SLN metastases had an extremely good prognosis, with a 5-year OS>90% and a 5-year DDFS of 95%.

CONCLUSIONS

Clinically lymph node-negative T4 melanoma cases should be strongly considered for SLN biopsy, regardless of Breslow depth. SLN lymph node status is the most significant prognostic sign among these patients. T4 patients with a negative SLN have an excellent prognosis in the absence of ulceration and should not be considered candidates for adjuvant high-dose interferon.

Prognostic significance of a positive nonsentinel lymph node in cutaneous melanoma

PURPOSE

Sentinel lymph node (SLN) biopsy provides important prognostic information for patients with cutaneous melanoma. There may be additional prognostic significance to melanoma spreading from the SLN to nonsentinel lymph nodes (NSLN). We examined the implications of a positive NSLN for overall and distant disease-free survival.

METHODS

Using a prospectively maintained, Institutional Review Board-approved melanoma database we studied patients who had a cutaneous melanoma, a positive SLN, and a completion lymph node dissection (CLND). Survival was determined using a combination of hospital records and the Social Security Death Index (SSDI). Univariate and multivariate Cox regression analysis was performed to further characterize predictors of overall and distant disease-free survival. Kaplan-Meier analysis was used to generate survival curves.

RESULTS

A total of 429 patients with positive SLN biopsies were identified, with at least one positive NSLN identified in 71 (17%). Median follow-up time was 36.8 months. Presence of a positive NSLN was significantly associated with poor outcome, although long-term survival was possible. Presence of ulceration, high mitotic rate, angiolymphatic invasion, total number of positive nodes, and volume of disease>1% in the SLN were significant predictors of survival on univariate analysis, but lost significance on multivariate. Multivariate Cox analysis revealed several predictors of overall survival: increasing age [hazard ratio (HR) 1.04, P<0.01], Breslow depth (HR 1.76, P<0.01), presence of extracapsular extension in the SLN (HR 2.39, P<0.01), and positive NSLN (HR 1.92, P<0.01).

CONCLUSION

Among node-positive melanoma patients, presence of a positive NSLN is a highly significant poor prognostic sign, even after considering the total number of positive nodes and volume of disease in the SLN. CLND after a positive SLN provides this important prognostic information.

Do micromorphometric features of metastatic deposits within sentinel nodes predict nonsentinel lymph node involvement in melanoma?

INTRODUCTION

Multiple attempts have been made to identify melanoma patients with a positive sentinel lymph node (SLN) who are unlikely to harbor residual disease in the nonsentinel lymph nodes (NSLN). We examined whether the size and location of the metastases within the SLN may help further stratify the risk of additional positive NSLN.

METHODS

A review of our Institutional Review Board (IRB)-approved melanoma database was undertaken to identify all SLN positive patients with SLN micromorphometric features. Univariate logistic regression techniques were used to assess potential significant associations. Decision tree analysis was used to identify which features best predicted patients at low risk for harboring additional disease.

RESULTS

The likelihood of finding additional disease on completion lymph node dissection was significantly associated with primary location on the head and neck or lower extremity (P = 0.01), Breslow thickness >4 mm (P = 0.001), the presence of angiolymphatic invasion (P < 0.0001), satellitosis (P = 0.004), extranodal extension (P = 0.0002), three or more positive SLN (P = 0.02) and tumor burden within the SLN >1% surface area (P = 0.004). Sex, age, mitotic rate, ulceration, Clark level, histologic subtype, regression, and number of SLN removed had no association with finding a positive NSLN. Location of the metastases (capsular, subcapsular or parenchymal) showed no correlation with a positive NSLN. Decision tree analysis incorporating size of the metastatic burden within the SLN along with Breslow thickness can identify melanoma patients with a positive SLN who have a very low risk of harboring additional disease with the NSLN.

CONCLUSION

Size of the metastatic burden within the SLN, measured as a percentage of the surface area, helps stratify the risk of harboring residual disease in the nonsentinel lymph nodes (NSLN), and may allow for selective completion lymphadenectomy.

The effects of TeleWound management on use of service and financial outcomes

This study investigated the effects of a TeleWound program on the use of service and financial outcomes among homebound patients with chronic wounds. The TeleWound program consisted of a Web-based transmission of digital photographs together with a clinical protocol. It enabled homebound patients with chronic pressure ulcers to be monitored remotely by a plastic surgeon. Chronic wounds are highly prevalent among chronically ill patients in the United States (U.S.). About 5 million chronically ill patients in the U.S. have chronic wounds, and the aggregate cost of their care exceeds $20 billion annually. Although 25% of home care referrals in the U.S. are for wounds, less than 0.2% of the registered nurses in the U.S. are wound care certified. This implies that the majority of patients with chronic wounds may not be receiving optimal care in their home environments. We hypothesized that TeleWound management would reduce visits to the emergency department (ED), hospitalization, length of stay, and visit acuity. Hence, it would improve financial performance for the hospital. A quasi-experimental design was used. A sample of 19 patients receiving this intervention was observed prospectively for 2 years. This was matched to a historical control group of an additional 19 patients from hospital records. Findings from the study revealed that TeleWound patients had fewer ED visits, fewer hospitalizations, and shorter length of stay, as compared to the control group. Overall, they encumbered lower cost. The results of this clinical study are striking and provide strong encouragement that a single provider can affect positive clinical and financial outcomes using a telemedicine wound care program. TeleWound was found to be a credible modality to manage pressure ulcers at lower cost and possibly better health outcomes. The next step in this process is to integrate the model into daily practice at bellwether medical centers to determine programmatic effectiveness in larger clinical arenas.

The impact of factors beyond Breslow depth on predicting sentinel lymph node positivity in melanoma

BACKGROUND

In addition to Breslow depth, the authors previously described how increasing mitotic rate and decreasing age predicted sentinel lymph node (SLN) metastases in patients with melanoma. The objectives of the current study were to verify those previous results and to create a prediction model for the better selection of which patients with melanoma should undergo SLN biopsy.

METHODS

The authors reviewed 1130 consecutive patients with melanoma in a prospective database who underwent successful SLN biopsy. After eliminating patients aged <16 years and patients who had melanomas that measured <1 mm, 910 remaining patients were reviewed for clinical and pathologic features and positive SLN status. Univariate association of patient and tumor characteristics with positive SLN status was explored by using standard logistic regression techniques, and the best multivariate model that predicted lymph node metastases was constructed by using a backward stepwise-elimination technique.

RESULTS

The characteristics that were associated significantly with lymph node metastasis were angiolymphatic invasion, the absence of regression, increasing mitotic rate, satellitosis, ulceration, increasing Breslow depth, decreasing age, and location (trunk or lower extremity compared with upper extremity or head/neck). Previously reported interactions between mitotic rate and age and between Breslow depth and age were confirmed. The best multivariate model included patient age (linear), angiolymphatic invasion, the number of mitoses (linear), the interaction between patient age and the number of mitoses, Breslow depth (linear), the interaction between patient age and Breslow depth, and primary tumor location.

CONCLUSIONS

Younger age, increasing mitotic rate (especially in younger patients), increasing Breslow depth (especially in older patients), angiolymphatic invasion, and trunk or lower extremity location of the primary tumor were associated with a greater likelihood of positive SLN status. The current results support the use of factors beyond Breslow depth to determine the risk of positive SLN status in patients with cutaneous melanoma.

Predictors of Nonsentinel Lymph Node Positivity in Patients with a Positive Sentinel Node for Melanoma

BACKGROUND

Patients found to harbor melanoma micrometastases in the sentinel lymph node (SLN) are recommended to proceed to complete lymph node dissection (CLND), although the majority of patients will have no additional disease identified in the nonsentinel lymph nodes (NSLNs). We sought to assess predictive factors associated with finding positive NSLNs, and identify a subset of patients with low likelihood of finding additional disease on CLND.

STUDY DESIGN

We queried our prospective melanoma database for patients from January 1996 to August 2003 with a positive SLN. Univariable logistic regression models were fit for multiple factors and a positive NSLN. To derive a probabilistic model for occurrence of one or more positive NSLN(s), a multivariable logistic model was fit using a stepwise variable selection method.

RESULTS

Of 980 patients who underwent SLN biopsy for cutaneous melanoma, 232 (24%) had a positive SLN; 221 (23%) followed by CLND. Of these patients, 34 (15%) had one or more positive NSLN(s). In multivariable analysis, male gender (odds ratio [OR] 3.6 [95% CI 1.33, 9.71]; p = 0.01), Breslow thickness (OR 4.58 [95% CI 1.28, 16.36]; p = 0.019), extranodal extension (OR 3.2 [95% CI 1.0, 10.5]; p = 0.05), and three or more positive sentinel nodes (OR 65.81 [95% CI 5.2, 825.7]; p = 0.001) were all associated with the likelihood of finding additional positive nodes on CLND. Of 47 patients with minimal tumor burden in the SLN, only 1 (2%) had additional disease in the NSLN.

CONCLUSIONS

These results provide additional data to plan clinical trials to answer the question of who can safely avoid CLND after a positive SLN. Patients with minimal tumor burden in the SLN might be the most likely group, although defining "minimal tumor burden" must be standardized. Serial sectioning and immunohistochemistry on the NSLN in any "low-risk" group must be performed in a clinical trial to confirm that residual disease is unlikely before avoiding CLND can be recommended.

The use of a bovine collagen construct for reconstruction of full-thickness scalp defects in the elderly patient with cutaneous malignancy

Full-thickness defects of the scalp following cancer resection are reconstructive challenges when bone is exposed. Local, regional, and/or free tissue transfer have all been described for reconstruction when the pericranium is exposed. We examined the surgical outcomes from 23 patients who underwent placement of bovine collagen constructs. Thereafter, delayed skin grafting was performed. The average age of the patients was 70 years. All patients had one of the following: melanoma (n = 13) squamous cell carcinoma (n = 5), angiosarcoma (n = 2), basal cell carcinoma (n = 1), spindle cell carcinoma (n = 1), or malignant pilar tumor (n = 1). The average defect size was 51 cm, with a range of 9 cm to 169 cm. Average time between bovine construct placement and skin grafting was 30 days. Histologic studies demonstrated persistence of the construct and infiltration of nascent fibroblasts. Six patients had delayed healing due to microabscesses in the constructs. All wounds eventually healed. In the elderly, this is a simple method to treat full-thickness scalp defects.

Endothelial barrier dysfunction caused by LPS correlates with phosphorylation of HSP27 in vivo

Lung edema during sepsis is triggered by formation of gaps between endothelial cells followed by macrophage infiltration. Endothelial gap formation has been proposed to involve changes in the structure of the actin filament cytoskeleton. Heat shock protein 27 (HSP27) is believed to modulate actin filament dynamics or structure, in a manner dependent on its phosphorylation status. We hypothesized that HSP27 may play a role in endothelial gap formation, by affecting actin dependent events in endothelial cells. As there has been no report concerning HSP27 in lung edema in vivo, we examined induction and phosphorylation of HSP27 in lung following LPS injection, as a model of sepsis. In lung, HSP27 mainly localized in capillary endothelial cells of the alveolus, and in smooth muscle cells of pulmonary arteries. HSP27 became significantly more phosphorylated at 3 h after LPS treatment, while the distribution of HSP27 remained unchanged. Pre-treatment with anti-TNFalpha antibody, which has been shown to reduce lung injury, blocked increases in HSP27 phosphorylation at 3 h. HSP27 phosphorylation was also increased in cultured rat pulmonary arterial endothelial cells (RPAEC) by treatment with TNFalpha, LPS, or H2O2. This phosphorylation was blocked by pre-treatment with SB203580, an inhibitor of the upstream kinase, p38 MAP kinase. Increased endothelial permeability caused by H2O2 in vitro was also blocked by SB203580. The amount of actin associated with HSP27 was reduced after treatment with LPS, or H2O2. In summary, HSP27 phosphorylation temporally correlated with LPS induced pathological endothelial cell gap formation in vivo and in a cell culture model system. This is the first report of increased HSP27 phosphorylation associated with pathological lung injury in an animal model of sepsis.

Reliability of sentinel lymph node mapping with biopsy for head and neck cutaneous melanoma

OBJECTIVES

To determine (1) the reliability of sentinel lymph node mapping with biopsy (SLNB) in head and neck cutaneous melanoma to accurately stage nodal basins and (2) the safety of SLNB in both the neck and parotid regions.

DESIGN

Retrospective cohort study with a median follow-up of 25 months. All patients had a minimum follow-up of 1 year.

SETTING

Academic medical center.

PATIENTS

Eighty evaluable patients diagnosed as having head and neck cutaneous melanoma and staged using SLNB.

INTERVENTIONS

Sentinel lymph nodes were identified using preoperative lymphoscintigraphy and a combination of intraoperative gamma probe and isosulfan blue dye. Patients with a SLN positive for melanoma underwent therapeutic lymphadenectomy followed by an evaluation for adjuvant therapies. Patients with a negative SLNB result were followed up clinically.

MAIN OUTCOME MEASURES

Percentage of positive SLNs, regional recurrence in the setting of a negative SLNB result (false-negative rate), and procedure complications.

RESULTS

The mean Breslow depth was 2.35 mm. A SLN was identified in 77 (96.3%) of cases, with an average of 2.18 nodes per patient. Of the sentinel nodes identified, 74% were from the neck region. The remaining 26% were from the parotid basin. No facial nerve complications occurred. Of the patients, 14 (18%) were SLN positive for metastatic melanoma. The regional failure rate in the setting of a negative SLNB result was 4.5%.

CONCLUSIONS

Sentinel lymph node mapping with biopsy is a reliable technique to diagnose regional spread from head and neck cutaneous melanoma. This procedure can be performed in both neck and parotid nodal basins with safety and accuracy similar to non-head and neck sites.

MAP kinase pathways involving hsp27 regulate fibroblast-mediated wound contraction

BACKGROUND

Heat shock protein 27 (hsp27) has been shown to modulate actin arrays in a manner dependent on its phosphorylation status. Hsp27 is phosphorylated by mitogen-activated protein kinase-activated protein kinase 2/3, which is regulated by mitogen-activated protein (MAP) kinases. We hypothesize that hsp27 phosphorylation modulates wound contraction.

MATERIALS AND METHODS

In these studies, a specific p38 MAP kinase inhibitor, SB203580, and a specific MAPK/extracellular signal-regulated kinase kinase 1,2 inhibitor, PD98059, were used to inhibit kinase activity. The effect of MAP kinase inhibitors was tested using a tissue culture model, the fibroblast-populated collagen lattice (FPCL) contraction assay, and a rat full-thickness skin defect model of wound healing. Hsp27 phosphorylation status was determined by isoelectric focus and Western blot analysis.

RESULTS

We show here that hsp27 phosphorylation correlates with FPCL contraction and with contraction in vivo. In the tissue culture model, each inhibitor reduced FPCL contraction and hsp27 phosphorylation. Hsp27 phosphorylation correlated with both p38 and ERK1, 2 activation. Hsp27 was highly phosphorylated in the wound edge during wound healing in a rat in vivo model. The phosphorylation status was highest in the granulation tissue. Treatment with both kinase inhibitors significantly delayed wound contraction in vivo, which correlated with inhibition of hsp27 phosphorylation.

CONCLUSIONS

This study demonstrates that ERK and p38 kinase cascades play important roles in wound contraction. Additionally, these data implicate hsp27 as being a key molecule in modulating the effects of these kinases.

Role of glutathione redox dysfunction in diabetic wounds

We propose that diabetic foot ulcers and diabetic mouse wounds have insufficient glutathione to maintain correct cellular redox potential. Therefore, tissue samples from the wound edge of diabetic foot ulcers, diabetic mice wounds and nondiabetic mice wounds were obtained. Levels of glutathione, cysteine, and mixed protein disulfide were determined and topical application of esterified glutathione in carboxymethylcellulose or carboxymethylcellulose alone was applied to the mice wounds. Diabetic foot ulcer mean glutathione levels were 150.6 pmol/mg in the controls and 53.4 pmol/mg at the wound edge (p < 0.05), while mean cysteine levels were 22.3 pmol/mg in the control and 10.5 pmol/mg at the wound edge (p < 0.05). The mixed protein disulfide levels were elevated in the wounds (14.6 pmol/mg), but not in the control (6.9 pmol/mg) (p < 0.05). The glutathione levels were lower in the diabetic mouse wounds (155 pmol/mg) than the nondiabetic mouse wounds (205 pmol/mg) (p=0.04). The diabetic mouse treated with carboxymethylcellulose alone healed slower (19.5 +/- 2.2 days) than the nondiabetic mouse DM (11.5 +/- 0.5 days) (p < 0.001). The diabetic mouse that received topical glutathione healed significantly faster (12.5 +/- 0.8 days) than the carboxymethylcellulose-treated mice (19.5 +/- 2.2 days) (p < 0.001). Glutathione levels in the diabetic mouse (26.0 pmol/mg) were lower than in the nondiabetic mouse (311.7 pmol/mg) (p < 0.05) after glutathione treatment. In the glutathione-treated diabetic mouse, the oxidized glutathione was higher (26.7%) than in the nondiabetic mouse (9.9%) (p=0.05). These data suggest that cellular redox dysfunction and lower glutathione levels are present in diabetic foot ulcers and diabetic mouse wounds.

Use of a cell-based interactive wound dressing to enhance healing of excisional wounds in nude mice

The need to have viable, metabolically active cells to heal wounds is well recognized, because there is clear evidence that cellular dysfunction delays healing. This suggests that addition of metabolically active cells to a delayed healing tissue could enhance the healing of the tissue. Therefore, we examined the ability of an interactive wound dressing composed of human keratinocytes or fibroblasts grown on microporous bio-reactor beads and placed into a polyethylene bag to facilitate the delayed healing of wounds in nude mice. A 1 x 1 cm wound was made on the backs of nude mice, and the dressing with or without viable cells was placed on the wound for 8 to 24 days, with dressing changes every other day. Wound area and time to heal measurements were compared after various interventions including freeze-thawing. The data shows that the interactive wound dressing was more effective than the control dressings (p<0.05) and that keratinocytes were more effective than fibroblasts in wound healing (p<0.05). Freezing-thawing of the interactive wound dressings destroyed the activity of the dressing. Studies examining cells using a live/dead viability assay showed that both keratinocytes and fibroblasts were alive after 2 days on the mice. Surprisingly, human fibroblasts appeared to exhibit bridging behavior that is indicative of fibroblast proliferation. We conclude that a simple interactive wound dressing using either keratinocytes or fibroblasts can enhance the healing of wounds in nude mice.

TGF-beta3 in the treatment of pressure ulcers: a preliminary report

OBJECTIVE

To determine the safety, tolerability, and efficacy of TGF-beta3 in the treatment of chronic, nonhealing pressure ulcers.

DESIGN

A subset analysis of data from a randomized, blind, parallel, placebo-controlled trial involving 270 patients.

SETTING

University of Michigan Wound Care Center.

PATIENTS

A total of 14 patients (6 women and 8 men aged > or = 18 years) with pressure ulcers were randomly assigned to 1 of 3 groups to receive once daily topical application of recombinant TGF-beta3 or placebo gel for a period of no more than 16 weeks. Group 1 (n=4) received 1.0 microg/cm2 of TGF-beta3, Group 2 (n=5) received 2.5 microg/cm2 of TGF-beta3, and Group 3 (n=5) received placebo gel. All subjects received standardized wound care as well. Weekly evaluations were performed for efficacy, determined by relative wound surface areas and volumes, and were compared with initial baseline values and safety parameters.

MAIN OUTCOME MEASURE

Reduction in pressure ulcer area and volume.

MAIN RESULTS

Group 2 had a significantly increased rate of wound healing at the fourth visit (P<.05). No significant difference was observed in the healing rate among the groups at the termination of the study. Treatment with TGF-beta3 was well tolerated and there were no significant adverse reactions.

CONCLUSION

The findings of this study indicate that the topical application of TGF-beta3 is safe and useful in the treatment of pressure ulcers and is most effective at the earliest stages of therapy.

Role of platelet-derived growth factor as an adjunct to surgery in the management of pressure ulcers

Management options for pressure ulcers include local wound care, surgical repair, and, more recently, topical application of platelet-derived growth factor (PDGF). PDGF is a glycoprotein that is mitogenic for mesenchymal cells and has been studied extensively for applicability in promoting the healing of chronic human wounds. Using data obtained from a multicenter clinical trial for the treatment of full-thickness pressure ulcers, a subset analysis was performed to investigate the outcome of salvage surgery for pressure ulcers, after incomplete closure occurred with the topical use of either recombinant human PDGF-BB (rhPDGF-BB) or placebo gel. At the University of Michigan Wound Care Center, subset data from a randomized, double-blind, placebo-controlled, parallel group clinical trial were reviewed to compare the effects of three concentrations of rhPDGF-BB on full-thickness pressure ulcers of the trunk with those of the placebo. Twenty-eight patients were enrolled and 27 completed the trial. An intent-to-treat analysis was used to evaluate data. If the ulcer did not heal by the end of the 16-week trial period, the surgeon, still blinded to the treatment group, offered salvage surgical repair of the pressure ulcer. Eleven patients underwent salvage surgical repair using myocutaneous flaps, primary closure, or skin grafts. Of three patients who received placebo followed by surgery, none progressed to full healing within 1 year. Of 12 patients in the treatment group who received rhPDGF-BB and salvage surgery, 11 (92 percent) ultimately healed the ulcers within 1 year after the start of the clinical trial. These findings suggest that treatment with rhPDGF-BB before surgery enhances the ability to achieve a closed wound over surgery alone. It must yet be determined to what degree rhPDGF-BB contributed to the excellent results seen in the rhPDGF-BB/surgery group. It is possible that rhPDGF-BB "primes" the local wound milieu to make it more responsive to complete closure following surgical treatment.

Osteomyelitis related to pressure ulcers: the cost of neglect

Twelve patients with documented chronic osteomyelitis of the pelvis resulting from truncal pressure ulcers were examined retrospectively to identify the cost of treatment for this significant health care problem. The retrospective review of each case spanned an 18-month period--6 months prior to the initial positive bone biopsy to 1 year following bone biopsy. The financial charges associated with treatment of osteomyelitis were identified using the University of Michigan Health System's databases for hospital charges, professional charges, and pharmacy charges. Prior treatment of these patients included surgical debridement of the pressure ulcer, pelvic bone biopsy, and culture-specific antibiotic therapy. The total charges for this group of 12 patients was $715,204, or an average charge of $59,600 per patient. Each patient was hospitalized, with hospitalization charges of $587,212, or an average of $48,934 per patient. Pharmacy charges for culture-specific antibiotics totaled $85,217 for the 12 patients. Six of 8 flap repairs achieved successful surgical closure of the pressure ulcer (75%) postantibiotic therapy. Surgery charges are not included in the totals.

Becaplermin gel in the treatment of pressure ulcers: a phase II randomized, double-blind, placebo-controlled study

Pressure ulcers are associated with significant rates of morbidity and mortality, particularly in the geriatric and spinal cord-injured populations. Newer pharmacologically active therapies include the use of topically applied recombinant human platelet-derived growth factor-BB (becaplermin), the active ingredient in REGRANEX) (becaplermin) Gel 0.01%, which has been approved in the United States for treatment of lower extremity diabetic neuropathic ulcers that extend into the subcutaneous tissue or beyond and have an adequate blood supply. In this study, the efficacy of becaplermin gel in the treatment of chronic full thickness pressure ulcers was compared with that of placebo gel. A total of 124 adults (>/= 18 years of age) with pressure ulcers were assigned randomly to receive topical treatment with becaplermin gel 100 microg/g (n = 31) or 300 microg/g (n = 32) once daily alternated with placebo gel every 12 hours, becaplermin gel 100 microg/g twice daily (n = 30), or placebo (sodium carboxymethylcellulose) gel (n = 31) twice daily until complete healing was achieved or for 16 weeks. All treatment groups received a standardized regimen of good wound care throughout the study period. Study endpoints were the incidence of complete healing, the incidence of >/= 90% healing, and the relative ulcer volume at endpoint (endpoint/baseline). Once-daily treatment of chronic pressure ulcers with becaplermin gel 100 microg/g or 300 microg/g significantly increased the incidences of complete and >/= 90% healing and significantly reduced the median relative ulcer volume at endpoint compared with that of placebo gel (p < 0.025 for all comparisons). Becaplermin gel 300 microg/g did not result in a significantly greater incidence of healing than that observed with 100 microg/g. Treatment with becaplermin gel was generally well tolerated and the incidence of adverse events was similar among treatment groups. In conclusion, once-daily application of becaplermin gel is efficacious in the treatment of chronic full thickness pressure ulcers.

Effects of glutathione depletion on oxidant-induced endothelial cell injury

Ischemia-reperfusion produces edema in vivo by disrupting endothelial cell junctional integrity. A cultured rat pulmonary artery endothelial cell (RPAEC) model was used to analyze the effects of oxidants and ischemic plasma in vitro. RPAEC cultures were treated with ischemic human plasma from transverse rectus abdominis musculocutaneous (TRAM) flaps following mastectomy or with an equal quantity of nonischemic plasma taken peripherally. Endothelial cells treated with ischemic plasma rounded and formed gaps within 5 min, then ruffled and blebbed after 10 min. Cultures treated with human nonischemic plasma had no gross morphological changes. Additionally, cultures treated with human ischemic plasma demonstrated an increase in diffusion rate of 125I-albumin across monolayers while monolayers treated with human nonischemic plasma had no increase in diffusion rate. RPAEC monolayers were treated with malic acid diethyl ester (DEM) or L-buthionine-[S, R]-sulfoximine (BSO) to decrease cellular stores of glutathione before exposure to oxidant stress. Cultures depleted of cellular glutathione stores were significantly (P < 0.05) more susceptible to 50 microM H2O2 than controls, as determined by an increase in diffusion rate of 125I-albumin across monolayers. To determine if ischemic plasma effects were mediated by oxidants, cultures were depleted of glutathione by DEM or BSO pretreatment before exposure to plasma from the ischemic hind limbs of Sprague-Dawley rats. Glutathione-depleted RPAEC monolayers were significantly (P < 0.05) and substantially (2-3 X) more susceptible to the effects of ischemic plasma than were cultures with normal glutathione levels. Glutathione depletion had no effect on cultures treated with an equal amount of nonischemic plasma from sham-operated rats. These data strongly suggest that ischemic plasma in the absence of any cellular component are able to induce an oxidant injury in endothelial cells and thereby compromise junctional integrity.

TNF-alpha potentiates oxidant and reperfusion-induced endothelial cell injury

Pulmonary edema following reperfusion is a major clinical problem. Changes in endothelial cell shape induced by oxidant injury may account for immediate capillary leakage associated with reperfusion injury. In these experiments we examined the role of tumor necrosis factor-alpha (TNF-alpha) in acute endothelial cell injury following ischemia-reperfusion. Sprague-Dawley rats were treated with a neutralizing antisera directed against TNF-alpha prior to production of distal ischemia. These rats demonstrated a significant reduction (P < 0.05) in acute lung edema in response to 4 hr of ischemia and 30 min of reperfusion when compared to rats undergoing the same procedure without antisera treatment. An in vitro model was developed to determine if TNF-alpha had a direct effect on endothelial cell response to ischemia-reperfusion. The effects of TNF-alpha and oxidant stress on the integrity of cultured endothelial cell monolayers was measured. Rat pulmonary artery endothelial cell monolayers reacted in vitro to oxidant stress by an increase in permeability. The cells changed shape and an increase in diffusion of 125I-albumin across cell monolayers resulted when these cells were exposed to 50 microM hydrogen peroxide (H2O2) or plasma from the ischemic hind limb of a Sprague-Dawley rat (50 microliters/ml). Pretreatment of cultured cells with low levels of recombinant mouse TNF-alpha significantly affected both the cell shape change and the increase in permeability (P < 0.05). Increased permeability of cell monolayers in vitro was not due to cell lysis as determined by media lactate dehydrogenase levels. The effect appeared to be due to cellular rounding and contraction seen using video time lapse microscopy. These data suggest a direct effect of TNF-alpha on endothelial cells, whereby the cells are rendered more susceptible to oxidant injury accompanying reperfusion.

Oxidant stress: the role of the glutathione redox cycle in skin preconditioning

The role of the glutathione redox cycle in cellular protection form skin necrosis during the ischemic stress response (preconditioning) is unknown. In this series of experiments, we tested the hypothesis that oxidant stress reduces available total glutathione during injury and contributes to skin necrosis in flaps. Dorsal skin flaps (10 x 4 cm) were raised as acute flaps and skin grafts were obtained from the flaps at 0, 1, 4, 6, 12, or 24 hr. Some flaps were preconditioned as bipedicle flaps for 24, 48, 72, or 96 hr and the distal attachment divided before skin grafts were obtained 24 hr later. Flap survival was measured at 7 days. Total glutathione (GSH) and oxidized GSH (GSSG) were extracted and their levels determined enzymatically. Tissue GSH reductase (GR) activity was assayed with a spectrofluorometer and expressed as mumoles of NADPH oxidized/hr/g. Biochemical data were compared between the proximal and distal ends of the flaps using a two-tailed Student t test while differences between groups were compared using ANOVA. Skin necrosis was 5.4 +/- 0.12 cm in the distal ends at 7 days in acute flaps, while there was no skin necrosis in flaps preconditioned for 7 days. In acute flaps, total GSH levels fell precipitously in the distal end at 24 hr (P < 0.05). However, after 72 hr of preconditioning, the GSH levels in the distal end of the flap remained elevated while GSSG levels were undetectable. At 24 hr of ischemia, GR activity was 79 +/- 4 in the distal ends of acute flaps, while after preconditioning and 24 hr of ischemia, the GR activity increased to 172 +/- 13 in the distal ends (P < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Is aggressive surgical management justified in the treatment of Merkel cell carcinoma?

Since its original description in 1972, we have seen and personally treated a group of 15 patients with Merkel cell carcinoma at the Vanderbilt Medical Center and the Nashville VA Hospital. We will review the demographics, management, and clinical course of this extremely lethal but initially benign appearing cutaneous malignancy. The majority of lesions occur on the head and neck, followed by the extremities and trunk. Location of the primary tumor has no effect on outcome. Despite a high mortality in our series (10 of 15), early recognition and aggressive surgical therapy may be the only way to prolong survival. No other adjuvant therapy has proved effective.

Venoatrial pathways after the Mustard operation for transposition of the great arteries: anatomic and functional MR imaging

PURPOSE

To evaluate spin-echo (SE) and cine gradient-echo (GRE) magnetic resonance (MR) imaging with velocity mapping for detecting late complications of the Mustard operation.

MATERIALS AND METHODS

Twenty-one patients were studied with MR imaging 1-22 years after undergoing the Mustard operation. Twenty were also studied with transthoracic echocardiography, 18 with angiocardiography, and five with transesophageal echocardiography.

RESULTS

MR imaging showed no venoatrial obstruction in nine patients. This result was confirmed with angiocardiography in seven cases and postmortem examination in one case. In one case, MR imaging demonstrated a leak at the baffle suture line. Of 12 cases with venoatrial obstruction at MR imaging, nine were confirmed with angiocardiography or surgery. There were two false-positive MR studies and one case in which no conclusion was reached.

CONCLUSION

With addition of cine GRE sequences and velocity mapping to SE sequences, MR imaging is a useful noninvasive method of investigating late complications of the Mustard operation.

Acute skin injury releases neutrophil chemoattractants

BACKGROUND

Progressive or ongoing skin necrosis after traumatic injury is well known. Experimental evidence has associated these events with neutrophil activation and secondary oxidant injury. To determine the mechanism by which neutrophils migrate to a site of injury, cytokine release from injured skin was measured.

METHODS

Twenty-five skin biopsy specimens of acute partial thickness skin injuries were compared with uninjured skin of the same patient. Conditioned medium from explanted skin was assayed for tumor necrosis factor (TNF), interleukin-6 (IL-6), and IL-8.

RESULTS

Acute skin injury resulted in a significant release of IL-8 but not IL-6 or TNF. In eight patients gradient cytokine release was found; IL-8 levels for partial thickness burn were 26.4 ng/ml, for unburned skin adjacent to the burn were 2.1 ng/ml, and for distal normal skin were 0.2 ng/ml.

CONCLUSIONS

IL-8 is released from acutely injured skin; IL-6 and TNF are not. This selective release suggests a mechanism whereby neutrophils are recruited into injured tissue. These neutrophils might then induce further injury, increasing the extent of posttraumatic tissue loss.

dT diaphorase: increased enzyme activity and mRNA expression in oxidant stress of skin

DT diaphorase is a flavoprotein that enzymatically transfers two electrons from quinones as intermediate substrates and has been reported to increase its activity in the liver after exposure to toxicants. In this series of experiments, we tested the hypothesis that DT diaphorase also increases its activity after exposure to oxidants following gradient ischemia in skin. Using dorsal rat flaps, oxidant stress was induced immediately or during a 7-day period of preconditioning as a bipedicle flap before the distal attachment was divided. DT diaphorase activity (delta Abs/min/100 g) or expression of message was measured during the period of preconditioning to determine the relationship between skin survival, enzyme activity, and expression of message. There was 4.7 +/- 0.8 cm of skin necrosis in the distal end of acute flaps while the preconditioned flaps had no skin necrosis after the distal attachment was divided. In the acute flaps, the DT diaphorase activity was equal throughout the flap for the first 6 hr. After 24 hr of ischemia, the DT diaphorase activity was significantly higher in the proximal end of the flap (1.83 +/- 0.21 delta Abs/min/100 g) than that in the distal end (0.005 +/- 0.01 delta Abs/min/100 g), which was significant (P < 0.05). In the preconditioned flaps, enzyme activity did not increase but there was as 50-fold increase in DT diaphorase activity at the distal end 24 hr after they were divided (P < 0.05). Maximal enzyme induction of DT diaphorase activity occurred after 4 days of preconditioning and correlated with the maximal expression of mRNA. These studies provide the first evidence that DT diaphorase enzyme activity is inducible after oxidant stress. The data also suggests that DT activity remains elevated for at least 6 hr of ischemia and may be a potential source of anti-oxidant activity in ischemic skin.

Validation of measurement of regional myocardial perfusion in humans by ultrafast x-ray computed tomography

The objective was to validate the measurement of myocardial perfusion in humans by ultrafast computed tomography (CT), by comparing measurements with those from single photon emission computed tomography (SPECT). Measurement of myocardial perfusion with high spatial resolution (including the differentiation of subendocardial and subepicardial perfusion) may be possible by ultrafast CT in humans. Although there are encouraging data from experiments with dogs, the technique has not been validated in humans. In 11 patients, ultrafast CT measurement of regional perfusion in a single short-axis slice was compared with that obtained by SPECT, and in 14, reproducibility of ultrafast CT was evaluated. The ultrafast CT scanner was set to acquire 20 images, gated to end-diastole. The images were divided into 32 equal segments, and the time course and extent of opacification of the left ventricular cavity and myocardium were analyzed to calculate absolute perfusion. The thallium tomograms were also divided into 32 segments for comparison. The pattern of relative perfusion by segment was represented as a curve. In 18 of 22 paired scans, the mean difference of the position of the minimum and maximum points of the curves was less than 4, indicating close agreement between the two techniques. When scoring segmental perfusion as normal or abnormal, there was agreement between the methods in 129 of 176 segments ([symbol: see text] 0.41). Reproducibility (mean difference +/- 1 SD) of basal scans was 0.005 +/- 0.2 mL/min/mL, and during adenosine vasodilation was 0.05 +/- 0.32 mL/min/mL. Absolute perfusion (mean +/- 1 SD) at rest was 0.52 +/- 0.21 mL/min/mL. During adenosine infusion, perfusion increased to a mean of 0.84 +/- 0.42 mL/min/mL. Ultrafast CT and intravenous contrast can be used to assess relative myocardial perfusion in humans, at rest and during adenosine vasodilatation, although it may underestimate absolute perfusion, particularly at high flow.

Wound complications and treatment of the infected implantable cardioverter defibrillator generator

Since 1980, the automatic implantable cardioverter defibrillator (ICD) has evolved as effective therapy for prevention of sudden cardiac death following documented sustained ventricular tachycardia or fibrillation. During a 5-year period, 412 ICD devices were implanted at the University of Michigan Hospitals with a wound complication rate of 4.1%. In this group, there were 13 infections, 3 erosions of the generator pocket, and 1 wound hematoma. Of the 16 patients with infection or erosion, 12 patients were treated with a rectus abdominis muscle flap closure and 4 with ICD generator removal. In 83% (n = 12) of the muscle flap patients, the wound healed uneventfully. Preoperative chest CT scanning was found to be helpful in identifying probable infection of the epicardial leads. In these cases, all hardware had to be removed to achieve resolution of the infection. We concluded that rectus abdominis muscle flaps were helpful in salvaging infected or exposed ICD generators in the absence of infected epicardial leads.

Identification of xanthine oxidase activity following reperfusion in human tissue

In this series of experiments, we surveyed xanthine oxidase activity after microvascular transfer in the venous effluent after reperfusion of human rectus abdominis muscle (n = 8) and jejunum (n = 4). Enzyme activity was correlated with duration of ischemia and biochemical markers of cellular injury. Xanthine oxidase (XO) activity was measured spectrofluorometrically using a pterin assay, whereas cellular injury was measured with commercial creatinine phosphokinase activity assay and lipid peroxidation products using a spectrophotometer. The data demonstrated that XO activity was statistically significantly increased in muscle flaps kept at room temperature during ischemia compared with muscle flaps that were cooled (p < 0.05). Creatinine phosphokinase activity was also increased after 15 minutes of reperfusion in muscle flaps that were not cooled (p < 0.05). Two of the jejunal free flaps had ischemia times of > 1 hour and had elevated XO activity after reperfusion despite cooling (p < 0.05). Two other jejunal flaps had ischemia times of < 1 hour, but in one case, the XO activity was increased before harvest. The other case had no increase in XO activity.

Measurement accuracy of cardiac output in humans: indicator-dilution technique versus geometric analysis by ultrafast computed tomography

OBJECTIVES

The aim of this study was to evaluate measurement accuracy of cardiac output in humans by comparing the indicator-dilution technique with geometric analysis by ultrafast computed tomography.

BACKGROUND

Ultrafast computed tomography can be used to measure cardiac output by two methods. First, by scanning to obtain end-systolic and end-diastolic short-axis images of the ventricular cavities at sequential tomographic levels, the stroke volume and therefore the cardiac output can be calculated. Second, indicator-dilution theory (the Stewart-Hamilton equation) can be applied to measurements of the concentration of radiographic contrast in the blood pool after a bolus injection. The latter method has not been validated in humans.

METHODS

The accuracy of the geometric method itself was first established by comparing left and right ventricular stroke volumes in 29 patients without valvular regurgitation or an intracardiac shunt, whose left and right ventricular stroke volumes should have been identical (group A). In a subset of 17 patients, the geometric method was compared with the indicator-dilution method (group B).

RESULTS

Geometric analysis showed that the mean difference between left and right ventricular stroke volume was 1.8 +/- 7.3 ml, with a percentage SD of the differences of 9.3% (r = 0.9). Comparison wih indicator dilution-calculated cardiac output showed a mean difference of 0.079 +/- 1.22 liters/min, with a percent SD of the differences of 23.7% (r = 0.6). There was no improvement in this comparison with individual calibration of the scanner for each patient.

CONCLUSIONS

The disparity found between data obtained with the geometric and indicator-dilution methods may be a result of the hemodynamic effects of contrast medium or it may suggest the possibility that some assumptions of indicator-dilution theory are not valid.

Angioedema associated with lisinopril

Angioedema has been reported to occur in association with all angiotensin-converting enzyme inhibitors used in the United States. We reviewed nine cases of angioedema associated with lisinopril use seen in the emergency department at our hospital among 1,970 patients that had been prescribed lisinopril from March 1989 to May 1990. Cases were considered as probably (six cases) or possibly (three cases) drug related, depending on the temporal relationship of the initiation of therapy and the onset of angioedema. All of the cases had edema of the lips, buccal mucosa, and or face. None presented with laryngeal edema or stridor. The angioedema resolved within 1 to 2 days with diphenhydramine treatment and discontinuation of lisinopril. Our data suggest that the incidence of angioedema associated with lisinopril is greater than that associated with captopril or enalapril.

An improved method of in vivo wound disruption and measurement

Biomechanical studies of wound strength are important because of new investigations in growth factors, cytokines, and fetal wounds. We compared two traditional methods of wound disruption measurement with a novel computerized model designed for in vivo experiments. An Instron tensiometer (INSTS) and an air insufflated positive pressure device (AIPPD) were compared with a vacuum-controlled wound chamber device (VCWCD). The VCWCD produced vacuum at the wound site and wound disruption was monitored with two video camera/recorders. Rats were marked with a template guide for a 2.5 cm, full-thickness, abdominal incisional wound. Rats were divided into three groups and studied at 2, 7, or 14 days after wounding. The recorded images were computer digitalized to generate wound strength curves from a three-dimensional model. A comparison of the wound disruption curves demonstrated that the VCWCD was comparable to the INST or AIPPD in normal wound healing (P greater than .40). The VCWCD provided data with less standard error at 2 days after wounding (P less than 05). In separate series of experiments, VCWCD was tested in the early phases of healing and was found to be sensitive to change at intervals of 48 hr after wounding (P less than .005). The INST or AIPPD methods could not perform this task because of an unacceptable level of random error after tissue manipulation. The VCWCD system was considered superior for evaluating early wound healing because it was an in vivo method which required minimal wound manipulation.

Valve and great vessel stenosis: assessment with MR jet velocity mapping

For measurement of poststenotic jet velocities with magnetic resonance (MR) imaging, the authors reduced the echo time (TE) of the field even-echo rephasing (FEER) velocity mapping sequence from 14.0 to 3.6 msec, so minimizing the problem of MR signal loss from turbulent fluid. In vitro use of rotating disk and stenotic flow phantoms confirmed that the 3.6-msec TE sequence enables accurate measurement of jet velocities of up to 6.0 m/sec (r = .996). Peak jet velocity measurements were made with MR imaging in 36 patients with stenosis of native heart valves (n = 9), conduits (n = 19), or Fontan connections (n = 2) or with aortic coarctation (n = 6). Peak velocity measurements made with MR imaging agreed well with measurements made with Doppler ultrasound (US), which were available in 18 cases (standard deviation = 0.2 m/sec). Velocity mapping with fast-echo MR imaging is likely to have considerable importance as a noninvasive means of locating and evaluating stenoses, particularly at sites inaccessible to US, but care must be taken to prevent errors caused by malalignment, signal loss, phase wrap, or partial-volume effects.

Serum amyloid P component: its role in platelet activation stimulated by sphingomyelinase D purified from the venom of the brown recluse spider (Loxosceles reclusa)

Serum amyloid P component or serum amyloid protein is a ubiquitous, highly conserved glycoprotein whose function is unknown. Although the related pentraxin, C-reactive protein, is an acute phase reactant in man, there is no direct evidence that human serum amyloid protein is involved in an inflammatory response. Here we show that serum amyloid protein is required by sphingomyelinase D, the principal necrotic agent of the venom of Loxosceles reclusa, for the in vitro-activation of human platelets. Furthermore, this platelet activation is dependent upon the presence of only serum amyloid protein; no other plasma components are necessary. Secretion of [3H]-serotonin and aggregation of platelets are nearly maximal following incubation of the platelets with purified sphingomyelinase D (0.3 micrograms/ml) and 5 micrograms/ml pure serum amyloid protein in the presence of calcium. Since the platelets are no longer activated when this 10% physiologic amount of serum amyloid protein is omitted, serum amyloid protein is likely to have a role in the necrosis caused by brown recluse spider venom.

Magnetic resonance velocity mapping

Magnetic resonance velocity mapping is achieved by encoding velocity at each point in a tomographic imaging plane in the phase of the magnetic resonance signal. Although this can be achieved with almost any imaging sequence, cine gradient echo sequences are particularly suitable because of the high signal from blood and the ability to repeat the sequence rapidly to form a cine image. The technique has been shown to be accurate by in vitro and in vivo validation, with flow measurements in the great vessels having an accuracy of approximately 6%. A potential problem arises from loss of signal from turbulent blood flow, but this can be overcome with the use of even echo rephasing and echo times below 5 ms. Using such sequences, velocities of up to 6 m s-1 have been measured clinically and pressure gradients across valves as great as 16 kPa (120 mmHg) can be computed. Clinical application has centred on the measurement of flow in the pulmonary circulation and in shunts and conduits in patients with congenital heart disease. Other applications include the measurement of valvular regurgitation and stenosis, and flow in coronary artery bypass grafts. Flow in native coronary arteries has been measured but the technique requires further development before such measurements can be considered reliable. Real time imaging using echo planar velocity mapping has been achieved and it is hoped that this will make coronary artery flow measurements more robust.

Pulmonary artery distensibility and blood flow patterns: a magnetic resonance study of normal subjects and of patients with pulmonary arterial hypertension

Pulmonary artery distensibility was studied with spin-echo magnetic resonance imaging in 20 normal subjects of variable age and in four patients with pulmonary arterial hypertension. The distensibility was found to be significantly lower (8%) in patients with pulmonary arterial hypertension than it was in normal subjects (23%). No age-related difference occurred. Magnetic resonance velocity mapping of the pulmonary artery blood flow was performed in 26 normal subjects--11 had mapping in the mid pulmonary artery, 15 had mapping in the distal pulmonary artery, and mapping in the four patients with pulmonary arterial hypertension was in the mid pulmonary artery. The pulmonary artery flow volume was compared with aortic flow and left ventricular stroke volume and a very good correlation was found. A retrograde flow of 2% occurred in the normal subjects serving to close the pulmonic valve. Antegrade plug flow occurred in most normal subjects but varied among individuals. There were also other variations in the flow pattern among normal individuals. All patients with pulmonary arterial hypertension had a markedly irregular ante- and retrograde flow and a large retrograde flow (average 26%). Magnetic resonance imaging offers a noninvasive way to evaluate pulmonary arterial hypertension as well as to quantitate pulmonary and aortic flows in, for example, left-to-right shunts.

Chemical shift magnetic resonance imaging of human atheroma

Fifteen necropsy specimens of human descending aorta and from eight patients with atheromatous vascular disease were studied by magnetic resonance imaging at 0.5 T. Images were acquired in coronal and transverse planes to localised protruding lesions and then chemical shift imaging was performed by techniques described by Dixon and by Hinks. These techniques produce images in which signal strength is proportional to lipid content. The signal was expressed as a percentage of that from extravascular fat. The total lipid content and its distribution within the plaques were noted. After imaging, the postmortem specimens were examined histologically and the lipid content of the plaque was assessed on a semiquantitative scale. The distribution of lipid within the plaque and between intima and media was also noted. The findings of chemical shift imaging agreed well with histological examination both for total lipid content and for distribution within each plaque. Chemical shift imaging also provided an assessment of the lipid content of the plaques measured in living patients, but validation was more difficult. The usefulness of the technique in routine clinical practice remains to be established.

Regional aortic compliance studied by magnetic resonance imaging: the effects of age, training, and coronary artery disease

Arterial compliance was measured in 70 healthy volunteers, 13 athletes, and 17 patients with coronary artery disease. Magnetic resonance images were acquired at end diastole and end systole through the ascending aorta, the aortic arch, and the descending thoracic aorta. Regional compliance was derived from the change in luminal area in a slice of known thickness and from the pulse pressure. Total arterial compliance was also measured from the left ventricular stroke volume and the pulse pressure. In the volunteers, mean (SD) regional compliance (microliters/mm Hg) was greatest in the ascending aorta (37 (18], lower in the arch (31 (15], and lowest in the descending aorta (18 (8], and it decreased with age. Compliance in the athletes was significantly higher than in their age matched controls (41 (16) versus 22 (11) microliters/mm Hg). In the patients with coronary artery disease it was significantly lower (12 (4) v 18 (10] than in age matched controls. Total arterial compliance also fell with age in those with coronary artery disease although there was more variation. The results suggest a possible role for compliance in the assessment of cardiovascular fitness and the detection of coronary artery disease.

Quantitation of antegrade and retrograde blood flow in the human aorta by magnetic resonance velocity mapping

Magnetic resonance velocity mapping was used in 24 normal subjects to study two-dimensional velocity profiles in the proximal and mid-ascending aorta, and to quantify both forward and reverse flow. The aortic flow measurements were validated by comparison with left ventricular stroke volume in all subjects and by comparison with pulmonary flow measurements in 12. Agreement was good with standard errors of the estimate of 7.8 and 7.1 ml, and correlation coefficients of 0.93 and 0.95, respectively. Systolic velocity maps were similar in the proximal aorta and the mid-ascending aorta, with maximum early systolic flow along the left posterior wall. Toward the end of systole and throughout diastole, a channel of reverse flow developed in the same region in the mid-ascending aorta, but in the proximal aorta it split to enter the sinuses of Valsalva, predominantly the left and the right coronary sinuses. Mean percentage ratio of retrograde-to-antegrade flow was 6.3%, with the majority of retrograde flow occurring in early diastole. The findings suggest that the retrograde flow is related to coronary artery flow and it is possible that aortic disease, which is known to influence aortic flow patterns, may also influence coronary flow.

Left ventricular volume measured rapidly by oblique magnetic resonance imaging

Magnetic resonance measurements of left ventricular volume and ejection fraction based on measurements of area and length in a single oblique plane containing the long axis of the ventricle were compared with measurements made by summing the areas of the chamber in multiple contiguous slices. The multislice technique is known to be accurate, but the single slice technique is much quicker; it takes only nine minutes of acquisition time for both volume and ejection fraction. In 25 normal subjects there was good agreement between the two methods of measuring volume with a mean (SD) difference between measurements of 2.0 (6.6) ml. In 20 patients with previous infarction it was less good with a mean (SD) difference of 4.5 (18.1) ml. The mean (SD) difference of ejection fraction measurements was -0.019 (0.038) in the normal subjects and -0.059 (0.106) in the patients, and the discrepancy between the two techniques was greatest in the patients with a pronounced abnormality of wall motion and low ejection fraction. In a further 25 normal subjects, the agreement between single plane volume measurements in the vertical and horizontal long axis planes was good, indicating that either plane is suitable for rapid measurement. Single plane measurements of left ventricular volume and ejection fraction can be made with the accuracies stated, which are sufficient for routine clinical use except in patients with a pronounced abnormality of wall motion. In combination with measurements of regional wall thickness and motion, previously described, the technique offers a rapid non-invasive assessment of both global and regional left ventricular function.

Magnetic resonance velocity mapping in aortic dissection

We describe three patients with chronic aortic dissection in whom both spin-echo magnetic resonance imaging (MRI) and cine field-echo imaging were performed. The field even-echo rephasing (FEER) sequence showed the intimal flaps much more clearly than the spin-echo sequence and provided a distinction between thrombus and static blood. Velocity mapping allowed flow measurements in the true and false lumens. The management of the three patients was based upon the information provided by MRI. It is suggested that MRI may avoid invasive investigation and be the method of choice in haemodynamically stable patients with aortic dissection provided that the FEER sequence is used.

Brown recluse spider bites of the upper extremity

Brown recluse spider bites may cause painful, necrotic, slow-healing wounds. When these bites involve the hand and upper extremity, they can also create severe functional deficits and long-term disability. We reviewed an 11-year experience with brown recluse bites to the hand and upper extremity. Data from patients (n = 31) indicated a 20% incidence of functional complications (n = 6) unless conservative wound management, dapsone, and antibiotics were used. Delayed surgical excision was preferable until wounds were free from active inflammation. Painful, recurrent wound breakdown and hand dysfunction were more common with early surgical excision. These complications were successfully treated with steroids, sympathetic blockade, and early aggressive physical therapy.

Plasma components are required for platelet activation by the toxin of Loxosceles reclusa

We have used a partially purified toxin from the venom of the brown recluse spider, Loxosceles reclusa, to study its effects on human platelets isolated from plasma proteins. This toxin, which produced skin necrosis in rabbits, contained sphingomyelinase D activity. The toxin induced platelet aggregation and secretion of [3H]serotonin in human plasma but not in buffer or in human neonate plasma. Ca2+ was required for the interaction of toxin, platelets, and plasma factor(s). The addition of C-reactive protein restored aggregation and serotonin release of platelets incubated in human neonate plasma. The ADP-degrading enzyme, apyrase, and the non-steroidal, anti-inflammatory drug, indomethacin, inhibited platelet aggregation, suggesting that ADP secreted from platelet storage granules and indomethacin-sensitive pathway(s) are involve in the toxin-induced human platelet activation (aggregation and serotonin release). Generation of platelet activating factor (PAF) from the platelet by brown recluse toxin is not likely since the PAF receptor antagonist, BN 52021, did not inhibit platelet aggregation induced by the brown recluse toxin.

Magnetic resonance imaging of the pulmonary arteries and their systemic connections in pulmonary atresia: comparison with angiographic and surgical findings

Patients with pulmonary atresia require several investigations and operations. The role of magnetic resonance imaging in assessing the anatomy of the central pulmonary arteries, the origin and course of systemic collateral arteries, and the patency of surgical shunts has been studied with the aim of reducing the need for invasive angiography. Transverse, coronal, and sagittal images were obtained in ten adult patients and assessed without knowledge of surgical and angiographic data. Central pulmonary artery anatomy varied from full development to complete absence. Transverse slices showed hypoplastic arteries particularly well and the findings accorded with surgical and angiographic data in all patients. The origin and proximal course of 15 large collaterals were identified on the magnetic resonance images and 18 were identified by surgical and angiographic data. Magnetic resonance imaging did not show their distal connections; if such information is required angiography will be needed. Five surgical shunts were shown to be patent and two occluded at surgery and angiography, and this was confirmed on the magnetic resonance images. The patency of a further four shunts was uncertain, but they were not seen by magnetic resonance and were presumed to be occluded.

Blood flow patterns in the human aorta studied by magnetic resonance

Magnetic resonance velocity mapping by the field even echo rephasing sequence was used to provide two dimensional velocity profiles in the ascending and the descending aorta. Flow patterns were studied in ten healthy volunteers by a display method that gave clear details of the profiles. Velocity profiles in the ascending aorta were skewed in systole with an axis of skew roughly symmetrical about the plane of the aortic arch. During diastole flow was reversed along the posterior left wall of the ascending aorta while it continued forwards at the anterior right wall. In the descending aorta plug flow occurred but with minimal skew. Flow along the right wall was reversed during diastole. Turbulent flow did not occur in the ascending or descending aorta of any healthy subject. Magnetic resonance velocity mapping is a very powerful tool for the study of cardiovascular physiology. Its non-invasiveness, its quantitative two-dimensional data, its accuracy, and its high spatial resolution make it suitable for clinical use.