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Hepatocellular carcinoma (HCC) is an uncommon tumour, but its incidence is increasing in Canada and elsewhere. Currently, there are no Canadian recommendations for diagnosis and treatment of hcc, and possible options may have regional limitations. A consensus symposium was held in the Ottawa region to consider current diagnostic and management options for hcc. These recommendations were developed: Diagnosis-with adequate imaging, a biopsy is not required pre-surgery, but is required before the start of systemic therapy; lesions smaller than 1 cm should be followed and not biopsied; repeat biopsies should be core tissue biopsies; magnetic resonance imaging is preferred, but triphasic computed tomography imaging can be useful. Resection-recommended for localized HCC. Radiofrequency ablation-recommended for unresectable or non-transplantable HCC; should not be performed in the presence of ascites. Trans-arterial chemoembolization (TACE)-doxorubicin with lipiodol is the agent of choice; trans-catheter embolization is an alternative for patients if TACE is not tolerated or is contraindicated. Medical management-first-line sorafenib should be considered the standard of care. Transplantation-suitable patients meeting Milan criteria should be assessed for a graft regardless of other treatments offered. The authors feel that the recommendations from this consensus symposium may be of interest to other regions in Canada.

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We present a case of an exophytic spinal primitive neuroectodermal tumor that, radiologically, simulated an extramedullary nerve sheath tumor, meningioma, or metastatic tumor deposit. MR imaging provided discrete anatomic localization of the tumor, enabling exclusion of multicentricity in the brain and spinal cord.

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The purpose of this paper is to sensitize musculoskeletal and general sonographers to a wide variety of bony abnormalities that may be noted adjacent to soft tissues of interest. The authors gathered sonographic images displaying abnormalities involving the periosseous, periosteal and cortical tissues from numerous patients who underwent imaging in their department. When available, correlative imaging or the pathological diagnosis (or both) is provided. The authors conclude that musculoskeletal ultrasonography, when used to its full potential, can reveal corroborative and occasionally unsuspected evidence of underlying bony abnormalities, so that correlative imaging (e.g., plain radiography, computed tomography, magnetic resonance imaging or bone scanning) can be performed as appropriate.

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The atrioventricular (AV) node responds in a complex fashion to changes in activation rate. A variety of approaches have been used to explain these dynamic AV nodal responses, but none has been able to account fully for AV nodal behavior. Three specific rate-dependent properties of the AV node have been described: 1) time-dependent recovery after excitation, 2) an effect of short cycles to advance recovery ("facilitation"), and 3) a gradual slowing of conduction in response to sustained, high-frequency activation ("fatigue"). We hypothesized that a model incorporating quantitative descriptors of all three processes might be able to account for a wide variety of AV nodal behaviors. Quantitative descriptors of AV nodal recovery, facilitation, and fatigue were developed based on AV nodal conduction changes during selective pacing protocols in seven autonomically blocked dogs. These descriptors were incorporated into a set of mathematical equations that define AV nodal conduction of any beat based on activation history. The equations were then applied to predict pacing-induced Wenckebach periodicity in each dog. Experimental data were obtained after nine to 19 step decreases in atrial cycle length into the Wenckebach zone in each animal. Observed behaviors included complex patterns of block, a progressive increase in the level of block over 5 minutes of rapid pacing, and periods of alternating patterns of block. The model accurately predicted the onset of AV block at each cycle length, the relation between conduction ratio and cycle length as a function of time, and the changing patterns of Wenckebach periodicity during sustained atrial pacing. All three terms of the model equation (describing recovery, facilitation, and fatigue) were essential to account fully for the observed behaviors. Elimination of AV nodal fatigue from the model resulted in failure to account for time-dependent changes in Wenckebach patterns, whereas exclusion of facilitation led to consistent overestimation of the degree of AV block at each cycle length. We conclude that a mathematical model incorporating terms to describe recovery, facilitation, and fatigue accurately predicts a wide range of Wenckebach-type behavior and that complex conduction patterns of the AV node can be fully accounted for by simple functional AV nodal properties.

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Cycle length alternation (CLA) is commonly observed during supraventricular tachycardia (SVT) onset and termination. The present study was designed to gain insights into the mechanism and potential clinical relevance of CLA by comparing computer simulations of tachycardia to directly observed behavior in a canine model of AV reentrant tachycardia (AVRT). The computer model was based on the hypothesis that CLA is secondary to feedback between AV nodal output during SVT and subsequent AV nodal input, and used the measured anterograde AV nodal recovery curve (AV vs A1A2) to predict sequential AV and RR intervals during SVT. Orthodromic AVRT was created experimentally in 11 open-chested, autonomically-blocked (atropine plus nadolol) dogs using a sensing and pacing circuit that mimicked a retrograde-conducting accessory pathway. Steady-state cycle length and AV interval during experimental AVRT closely paralleled predictions made by the computer model. CLA appeared consistently at the onset of experimental AVRT at programmed VA intervals less than or equal to 100 msec (corresponding to VA less than or equal to 150 msec as measured clinically) in all dogs. The amplitude and duration of CLA increased as the VA interval decreased, and closely paralleled predictions based on the computer model. Abrupt accelerations in atrial pacing to the same rate as AVRT did not result in alternation of cycle length. In conclusion, alternation of cycle length results from feedback between AV nodal output and subsequent AV nodal input at the onset of reentrant supraventricular tachycardia, and does not require changes in autonomic tone or dual AV nodal pathways. CLA occurrence, amplitude, and duration are predictable based on AV node recovery properties, and depend on retrograde conduction properties of the reentrant circuit. The presence of CLA suggests that the AV node is an integral component of the SVT reentry circuit, and may be useful clinically to identify the mechanism of supraventricular tachycardias.

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The purpose of this study was to determine if the known frequency-dependent effects of diltiazem on inward calcium current result in selective actions during supraventricular tachycardia. These effects were evaluated by use of an experimental model of orthodromic atrioventricular reentrant tachycardia (AVRT). AVRT was induced in 15 dogs over a wide range of retrograde conduction times before and after two doses of diltiazem. Diltiazem produced a tachycardia-related suppression of atrioventricular nodal conduction resulting in greater efficacy for faster than for slower AVRTs. The degree of slowing for tachycardias that remained inducible after diltiazem administration was greater for AVRTs with a rapid initial rate (dose 1, 29%; dose 2, 40%) than for slower AVRTs (dose 1, 11%, p less than 0.01; dose 2, 18%, p less than 0.001). Rate-dependent AVRT slowing occurred because of a time-dependent phase of AH interval prolongation after the onset of tachycardia, which was observed only after diltiazem administration. to further clarify the mechanism of diltiazem's selective actions against faster tachycardias, its effects on the minimum pathway for reentry, or wavelength, were examined in four dogs. The ratio of refractory period to revolution time (RP/RT), an index of wavelength, was measured for each AVRT before and after diltiazem administration. Diltiazem increased the positive slope of the relation between RP/RT and the AVRT rate threefold compared with control (p less than 0.05). This rate-dependent effect prevented AVRT when RP/RT became greater than unity. In conclusion, rate-dependent atrioventricular node depression by diltiazem results in greater tachycardia slowing and higher rates of termination during atrioventricular reentrant tachycardias with faster initial rates and shorter retrograde conduction intervals.

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The present study concerns a report on the observations of supraclavicular nerves with abnormal passage though one or several intraclavicular bone canals. The explanation of the formation of interclavicular canals is found by the normal development of the clavicle. In most of the cases the bone canals are situated in the central part of the clavicule and rarely at the acromial end. The canals are either superficial or deep. Often bone bridges are formed. The bone canals and the supraclavicular nerves are barely visible on X-ray photographs. Polarising microscope analysis shows that the intraclavicular canals do not have the structure of the perforating canals of Volkmann. It can be deduced that the supraclavicular nerves have not pierced the bone substance already formed but, that they have been enclosed during later bone formation. Of the 254 cases studied (189 male and 65 female) the incidence of the described abnormality was 4% (10 cases) of which 3% were male.

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2 cases are described of a right recurrent nerve with abnormal origin and path. Frequency: 0,8%. Both cases ware associated with the presence of an A. lusoria. In the first case, the "non-recurrent" recurrent nerve reached the thyroid gland by its superior pole, in the second case by its inferior pole. In the latter case, there was a close relation between the nerve and the branches of the inferior thyroid artery. The consequences are discussed in relation to the surgical techniques.

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1. The dissection of 223 subjects has revealed 3 cases of A. lusoria (1.06%). In all these cases, the A. lusoria was the last branch of the aortic arch. 2. X-ray pictures were taken after injection of radio-opaque substance to elicit the topographical relations of A. lusoria with esophagus. 3. There were only small variations in the calibre and in the way of its branches. Right common carotid artery directly arose from the aortic arch. 4. The three Aa. lusoriae crossed the dorsal face of esophagus between the 4th and 2nd cervical vertebrae where they provoked at neat natch. 5. In one case, there was a marked narrowing at the origin of the artery. In another case, there was an initial widening of the artery. 6. Histological examination of the arterial wall from the portion between oesophagus and vertebral column demonstrated a decrease in number of elastic fibres towards the column. 7. In all cases, there was around A. lusoria a normal Ansa subclavia from the sympathetic trunk. 8. In one case, recurrent nervus were topographically normal on both sides. In both other cases, the right recurrent nerve did not pass under the right subclavian artery but went directly to the larynx without touching the right inferior thyroid artery and its branches.

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