Modified free pectoral skin flaps in rats.

Various types of murine free flaps have been developed for microsurgical training and research. We present a new modification of the free pectoral skin flap in Sprague-Dawley rats. Twelve free pectoral skin flaps were raised according to the standard protocol except that we deviated from it by transecting the common thoracic vessels at the origin of the axillary vessels and anastomosing them end-to-side to the femoral vessels in the groin. This reduced operating time and complications as well as postoperative morbidity and mortality. Overall, it simplified the procedure considerably and therefore made the model more attractive to beginners in microvascular surgery.

Imaging angiogenesis: perspectives and opportunities in tumour research - a method display.

The growth of solid tumours necessitates angiogenesis. The aim of this paper is the presentation and evaluation of different ex vivo methods for analysing tumour angiogenesis. Oral squamous cell carcinomas (SCC) were induced in mice by subcutaneous injection of tumour cells in the groin region and processed for histology and microvascular corrosion casting. Vascularization was analysed light microscopically using CD31 immunochemistry. Corrosion casts were analysed by scanning electron microscopy (SEM), micro computed tomography (µCT) and synchrotron radiation-based micro computed tomography (SRµCT). Immunochemistry allows for a simple and authentic detection and stereological quantification of the SCC vascularization. µCT imaging of the corrosion casts gives a high-quality overview over the three-dimensional (3D) microvascular architecture. SEM and SRµCT allow a high-definition display of the vessel morphology, providing magnificent detail recognition down to the capillary level enabling imaging of different forms of tumour angiogenesis, e.g., sprouting and intussusceptive angiogenesis. Immunochemistry and SEM are regarded as suitable for most of the morphometrical and morphological assessments because of the simple procedure and the high explanatory power, especially in combination with each other. High resolution SRµCT helps answering specialized questions, however, requires sophisticated data processing for visualization and is of limited availability.

Anatomic and flow dynamic considerations for safe right axillary artery cannulation.

OBJECTIVES: Neuroprotection is of paramount interest in cardiac surgery. Right axillary artery cannulation is well established in aortic surgery because it significantly improves survival and outcome, but malperfusion of the right brain after direct cannulation has been reported. Anatomically, 4 vessel segments are potentially amenable for cannulation of the subclavian and axillary arteries. Clinical studies vary widely in dissection sites and cannulation techniques. We investigated critical flow dynamics in the right brain caused by arterial inflow after direct cannulation and specified cannulation positions that provide optimal cerebral perfusion. METHODS: Distances from the lateral margin of the axillary artery and the subclavian artery to the origin of the vertebral artery were measured in 14 human corpses by a flexible ruler. We calculated the hemodynamics within the vertebral artery, depending on different positions of the cannula tip, in a computer-calculated model. RESULTS: The mean distance from the axillary artery to the vertebral artery was 8.5 cm, and the mean distance from the subclavian artery to the vertebral artery was 6.7 cm. Computed flow calculations demonstrated reversed flow in the vertebral artery when the cannula tip was positioned too close to its orifice. To ensure safe supra-aortic flow, a cannula can be inserted securely up to 6.0 cm into the axillary artery and 4.2 cm into the subclavian artery. CONCLUSIONS: Direct cannulation of the right axillary artery can lead to cerebral malperfusion, caused by an obstruction of the vertebral artery's orifice by the arterial cannula or a subclavian steal phenomenon due to flow reversal. The safety of direct axillary artery cannulation can be improved by a well-considered dissecting site and insertion length of the cannula.

Endovascular aneurysm repair: Magnetic resonance monitoring of histological organization processes in the excluded aneurysm.

BACKGROUND: The purpose of the present study was to systematically analyze the histopathologic organization processes in excluded aneurysms after endovascular stenting and to develop a noninvasive monitoring method for these processes using MRI. METHODS AND RESULTS: In 36 mongrel dogs, autologous aortic aneurysms were created. Endovascular treatment was performed using covered stents. Follow-up was after 1 week, 6 weeks, and 6 months. MRI was performed with T2-weighted turbo-spin-echo sequences and T1-weighted spin-echo sequences and was repeated after contrast bolus with gadolinium. Histopathologic findings were correlated to signal intensities (SIs) of MRI images. SIs of distinct areas were analyzed and related to the SI of the reference tissue (SI ratio). The histological organization process was gradated in the following 4 classes: class 0, detritus without organization; classes I and II, connective tissue proliferation with increasing fiber synthesis; and class III, dense fibrous connective tissue. The SI ratios of T2-weighted images were significantly reduced from 4.76 in detritus (0) to 1.70 in dense fibrous connective tissue (III) as a function of histopathologic classes. SI ratios of T1-weighted images were reduced from 1.84 (0) to 1.12 (III). Contrast bolus with gadolinium-DTPA showed no change of SI ratio in detritus (0.99) but an increase from 1.12 (I) to 1.70 (III) as organization increased. CONCLUSIONS: The histological organization of excluded aneurysms can be monitored by MRI. Progressive organization is indicated by decreasing SIs in T2- and an increasing signal increase in T1-weighted images after gadolinium bolus.