I read with interest the correspondence in the November issue about central venous catheter (CVC) malposition in the azygous arch . I report an interesting case of CVC malposition due to partial anomalous venous drainage. A 47-yr-old male was admitted to the intensive care unit (ICU) after an overdose of amitriptyline, complicated by a lower limb compartment syndrome requiring fasciotomy and subsequently above-knee amputation. By day 4 he required haemofiltration for renal failure consequent upon severe rhabdomyolysis. With strict asepsis a Vascath (catheter A) was inserted into the right subclavian vein together with a large bore multilumen CVC (catheter B) via a left internal jugular approach, neither with technical difficulty. The transduced pressures from both catheters were typically venous. A chest radiograph was taken to confirm position of the respective catheters. It was clear from the radiograph that the tips of the catheters were markedly displaced with catheter B appearing to be malpositioned (Fig. 1). The results of blood-gas analyses from simultaneous analysis of samples taken from each catheter are shown in Table 1. Catheter B was withdrawn by 5 cm and further blood samples were drawn again (Table 1). These results show that the multilumen catheter - inserted via the left internal jugular vein - was sampling oxygenated blood; however, when the catheter was withdrawn by 5 cm, the sampled blood became a 'venous admixture'. The multilumen catheter was removed uneventfully. The patient was discharged from the ICU 3 days later.
There are two possible explanations for these findings: first, catheter B initially advanced through a patent foramen ovale or an atrial septal defect - this is not supported by the radiographic position of the catheter. Second, catheter B was in a pulmonary vein and communicated with the left innominate vein via the left vertical vein. Partial anomalous pulmonary venous drainage, originally described by Winslow in 1739, is a congenital defect and an incidental finding in 0.7% of cadavers . Anomalous pulmonary venous connections more commonly involve the pulmonary veins of the right lung rather than the left lung. In the most common form, the right upper lobe pulmonary vein drains directly into the superior vena cava or right atrium. Echocardiography, cardiac catheterization and angiography are useful in defining the anatomy of partial anomalous venous drainage. Clinical diagnosis of isolated instances of partial anomalous venous drainage is rare. Where less than 50% of the pulmonary blood flow is shifted from left to right, it is generally asymptomatic and further evaluation is unwarranted. Greater shunt is associated with right atrial and ventricular dilatation leading to the development of dysrhythmias, right-sided heart failure and rarely pulmonary hypertension. About 10% of all patients with atrial septal defects will have anomalous pulmonary venous connections .
S. A. Townley
Department of Anaesthesia; Royal Hampshire County Hospital; Winchester, Hampshire; UK
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2. Hughes CW, Rumore PC. Anomalous pulmonary veins. Arch Path
3. Kalke BR, Carlson RG, Ferlic RM, Seller RD, Lillehei RW. Partial anomalous pulmonary venous connections. Am J Cardiol