PR05POST‐OPERATIVE HAEMATOMAS IN MICROVASCULAR FREE FLAP RECONSTRUCTION OF THE HEAD AND NECK: THE INCIDENCE,AETIOLOGY AND OUTCOME MODIFICATIONS

Background Free tissue transfer using microvascular surgery has become a safe a reliable means to repair soft tissue and/or bony defects of the head and neck. Operative success reaches 98%, however the incidence of significant post‐operative complication is also relatively high (32%). One common and often severe complication is haematoma formation at either donor or recipient sites. The incidence of recipient site haematoma is reported at 6%, however the causes and outcomes of haematomas have not been well investigated. A retrospective historical analysis of both donor and recipient site wound haematoma was performed to identify causative factors and the effect on patient outcome. Methodology A five year review was conducted for microvascular free tissue transfer to defects in the head and neck at The Royal Melbourne Hospital, for the period from February 2001 until February 2006. The medical records of these 150 patients were reviewed for donor and recipient site wound haematoma and outcomes. Results Significant factors for the development of post‐operative haematomas included lood pressure control during the first post‐operative, correlating with the likelihood of developing either a donor or recipient site haematoma (p value < 0.001), drain‐tube outputs (both high and low), smoking and the use of pre‐operative NSAIDs. Conclusion There are significant reversible factors that contribute to the development of post‐operative haematomas in head and neck surgery. Close monitoring of patient blood pressure by theatre and recovery nursing staff, close monitoring of drain outputs, and pre‐operative counselling on the use of NSAIDs and smoking may all be useful in the prevention of haematoma formation.     

Automatic algorithm for correcting motion artifacts in time-resolved two-dimensional magnetic resonance angiography using convex projections.

Time-resolved contrast enhanced magnetic resonance angiography (MRA) may suffer from involuntary patient motion. It is noted that while MR signal change associated with motion is large in magnitude and has smooth phase variation in k-phase, signal change associated with vascular enhancement is small in magnitude and has rapid phase variation in k-space. Based upon this observation, a novel projection onto convex sets (POCS) algorithm is developed as an automatic iterative method to remove motion artifacts. The presented POCS algorithm consists of high-pass phase filtering and convex projections in both k-space and image space. Without input of detailed motion knowledge, motion effects are filtered out, while vasculature information is preserved. The proposed method can be effective for a large class of nonrigid motions, including through-plane motion. The algorithm is stable and converges quickly, usually within five iterations. A double-blind evaluation on a set of clinical MRA cases shows that a completely unsupervised version of the algorithm produces significantly better rank scores (P=0.038) when compared to angiograms produced manually by an experienced radiologist.     

Composite aortic root replacement in acute type A dissection: time to rethink the indications?

OBJECTIVE: The indications for aortic root replacement in acute type A dissection are unclear. We reviewed the immediate and long-term outcome of consecutive patients in a series in which a low-threshold policy of composite aortic root replacement had evolved. METHODS: From a prospectively compiled aortic surgery database, we identified 162 patients who had either supracoronary interposition grafting, Group A (n=89), or composite root replacement, Group B (n=73) for acute type A dissection. Patients receiving total arch replacements were excluded. Operative and clinical details were analyzed and patient survival was compared to an age and gender matched census cohort. Need for reoperation on the proximal or distal aorta was also noted. Follow-up totaled 795.5 patient-years. RESULTS: Hospital mortality rates were identical in both groups (12.3%: 11 deaths in group A; 9 in group B). Chronic pulmonary disease, diabetes, malperfusion, hemodynamic compromise and aortic root dilatation were independent risk factors for hospital death. Actuarial survival estimates at 1, 5 and 10 years were 79% (71-88%), 64% (53-75%), and 55% (41-68%) for group A, and 79% (70-86%), 73% (62-83%), and 65% (52-78%) for group B (P=0.48). Age and operative patency of the ascending false lumen were independent risk factors for death after hospital discharge. Proximal aortic reoperation was required for four patients in group A and none in group B (P=0.085). CONCLUSION: A strategy of replacement rather than repair of the dissected aortic root for specific indications in type A dissection yielded high survival and low proximal reoperation rates. These results support an aggressive policy of composite root replacement in acute type A dissection.     

Glomerular filtration rate and N-terminal pro-brain natriuretic peptide as predictors of cardiovascular mortality in vascular patients.

OBJECTIVES: The purpose of this work was to assess the prognostic role of glomerular filtration rate (GFR) and NT-terminal pro-B-type natriuretic peptide (NT-proBNP) for mortality end points in the vascular population. BACKGROUND: The GFR and NT-proBNP have been shown to predict mortality end points in free-living and limited vascular populations, independent of traditional risk factors. However, their prognostic power in an unrestricted vascular population is poorly understood. METHODS: A total of 412 subjects from a vascular cohort with a history of either peripheral arterial disease (PAD) and/or other cardiovascular disease (CVD) were included in this prospective cohort analysis and followed for an average of 6.7 years. Outcome variables were all-cause mortality, ischemic heart disease (IHD) mortality, and any cardiovascular mortality. The prognostic roles of GFR and NT-proBNP levels were determined using multivariate survival analysis. RESULTS: Higher GFR (per 10 ml/min/1.73 m2) was significantly protective for all-cause mortality (hazard ratio [HR] 0.81, p < 0.001), IHD mortality (HR 0.82, p = 0.008), and CVD mortality (HR 0.84, p = 0.005). Conversely, NT-proBNP was not a significant predictor of any mortality end point. The GFR showed the strongest association in subjects with a history of other CVD. Although NT-proBNP did not demonstrate a significant prognostic role in any of the subgroups, the data were suggestive for patients with PAD alone. CONCLUSIONS: Glomerular filtration rate was a robust predictor of all-cause, IHD, and cardiovascular mortality in the vascular population, particularly in those with a history of other CVD, while NT-proBNP showed a suggestive association limited to the group with PAD only. These findings suggest that these markers must be selectively applied in the vascular population for greatest clinical utility.     

Optimal metabolite curve fitting for kinetic modeling of 11C-WAY-100635.

Many quantitative imaging protocols that make use of a metabolite-corrected arterial input function require the use of a mathematic model to describe the rate of metabolism of the radioligand. Commonly, parametric models are fit to metabolism data and then the fitted model is used to correct the plasma input function. (11)C-WAY 100635 is a rapidly metabolized radioligand used extensively in mapping the 5-hydroxytryptamine receptor 1A system. METHODS: To evaluate the adequacy of fit of 4 metabolite models, we examined data from 92 subjects who received an injection of (11)C-WAY 100635, were imaged with PET, and underwent measurement of total plasma concentration and metabolites. The performance of these models was assessed according to residual plots, as well as fit and information criteria. RESULTS: The study showed that the choice of model has a substantial effect on the resulting estimates of outcome measures. CONCLUSION: Among the models considered, the Hill model provides the best fit across all criteria.     

Characteristics of calcaneal bone infarction: an MR imaging investigation

Objective. Bone infarction (BI) of the calcaneus is an uncommon entity which has received little mention in the recent literature. In this paper, we review the MR images of six calcanei with BI, which demonstrate a pattern of presentation that may explain the etiology of BI at this unusual location. Design. A retrospective review was performed of the transcribed reports of the foot or ankle MR examinations at our institution. MR images of examinations with any marrow signal abnormality were reviewed for presence of BI and its distribution. Patients. Based on MRI criteria, four patients had calcaneal BI (none biopsy proven); they ranged in age from 37 to 51 years old. Two patients were diagnosed with systemic lupus erythematosus, one with fibrositis, and another with polymyositis. All were treated with corticosteroids. Results. Six calcanei (in four patients) contained a region of calcaneal BI. In five of the six, the lesions were entirely or predominantly located in the posterior half of the calcaneus. Conclusion. Two theories are proposed which may explain why BI predominantly occurs in the posterior half of the calcaneus. First, the convergence of the recurrent intraosseous calcaneal vessels may occasionally produce the equivalent of a single dominant vessel that is more prone to vascular accidents. Secondly, the region between the recurrent and the epiphyseal vessels may act as a watershed zone, increasing its susceptibility to ischemia.