Aberrant accessory

Fig. 4.2. Aberrant replaced right hepatic artery coming of the superior mesenteric artery (arrow) and aberrant accessory left hepatic artery (arrowhead) coming of the left gastric artery...

An aberrant hepatic artery refers to a branch that does not arise from its usual source (i.e. proper hepatic artery from the celiac trunk). This type of artery may be a substitute for the usual hepatic artery that is absent, in which case it is referred to as an aberrant replaced hepatic artery. In other cases there may be an additional artery to the one normally present hence the term aberrant accessory artery. 

This occurs in otherwise healthy individuals, who possess an anomalous (accessory) atrioventricular pathway they often experience attacks of paroxj mal AV re-entrant tachycardia or atrial fibrillation. Drugs that both suppress the initiating ectopic beats and delay conduction through the accessory pathway are used to prevent attacks e.g. flecainide, sotalol or amiodarone. Verapamil and digoxin may increase conduction through the anomalous pathway and should not be used. Electrical conversion may be needed to restore sinus rhythm when the ventricular rate is very rapid. Radiofrequency ablation of aberrant pathways will almost certainly provide a cure. 

Problems can also occur in patients with aberrant conduction pathways for example, verapamil caused an increased ventricular response in patients with Wolff-Parkinson-White syndrome associated with atrial fibrillation (9-11). The danger lies in provocation of ventricular fibrillation from advanced anterograde conduction in accessory pathways (12). 

Michels classic autopsy series of200 dissections, published in 1966, defined the basic anatomic variations in hepatic arterial supply, and has served as the benchmark for all subsequent contributions in this area (Table 20.1). Variant patterns occurred in 45% of cases, and the commonest arterial variant has been shown to be an aberrant right hepatic supply, which is seen in 13%-18% of patients (Coinaud 1986). Michels motivation was to maximize the database of the surgeon performing procedures in and around the porta hepatis, so as to avoid injury to vascular and ductal structures. A modification of the Michels classification was developed to reflect the presence of vessels that were either accessory or replaced, so that Michels original ten groups could be reduced to five major types and a most rare sixth variant (Hiatt et al. 1994) (Table 20.2) (Fig. 20.3). 

Common anatomical variations of penile arteries include asymmetry, bifurcated cavernosal artery, multiple cavernosal arteries, presence of recurrent branches, unilateral origin of all cavernosal branches, accessory cavernosal branches, and aberrant origin from the dorsal artery (Fig. 5.5). Occasionally the cavernosal artery consists of multiple short, rapidly tapering segments, periodically reconstituted by perforating vessels from the dorsal penile artery (Juskiewenski et al. 1982 Wahl et al. 1997). 

Perforating arteries, an important collateral pathway to the kidney, arise from the intraparenchymal branches of the renal artery and exit from the kidney to anastomose with various retroperitoneal arteries [18]. In addition to the main renal artery and perforating arteries, the superior, middle, and inferior capsular arteries should be considered as well. The superior capsular artery may arise from the inferior adrenal artery, main renal artery, or aorta. The middle capsular artery, which may consist of one or more branches, arises from the main renal artery. The inferior capsular artery may originate from the gonadal artery, an accessory or aberrant lower pole, or even the main renal artery. These vessels form a rich capsular network that anastomoses freely with perforating arteries and other retroperitoneal (especially lumbar) arteries and also with internal iliac, intercostal, and mesenteric arteries [18]. 

Fig. I5.I0a,b. Accessory soleus muscle (type 1). a Longitudinal extended field-of-view 12-5 MHz US image over the Achilles tendon (arrowheads) reveals the aberrant soleus muscle (arrows) inserting into the deep surface of the tendon. The muscle ends in proximity to the calcaneus and occupies a large part of Kager s space, b Axial CT scan confirms the presence of an accessory muscle (arrows) located between the distal Achilles tendon (At) and the flexor hallucis longus muscle (FHL)...

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