Risk Factors for Venous Obstruction in Children with Transvenous Pacing Leads FELICIA H. FIGA, BRIAN W. MCCRINDLF. JEAN-LUC BIGRAS. ROBERT M. HAMILTON, and ROBERT M. GOW From the Division of Cardiology. Deparfmcnt ot'P(!difitrirs, The Hospital for Sick Childrtm, aad the Faculty of Medicine, The University of Toruiito,Toronto, Ontario, Canada FIGA, F.H., ET AL. Risk Factors for Venous Obstruction in Children with Transvenous Pacing Leads. To determine tbe incidence and risk factor.^ for venous obstruction in children with transvenous pacing leads, 63 children were evaluated clinically and echocardiographically. Patients with abnormal clinical and/or echocardiographic findings were further investigated by venography. Thirteen patients (21%) had evi- dence of venous obstruction. Venography in 11 (2 refused) showed that severity of obstruction (as defined by percentage of luminal narrowing) was complete (100%) in 3, severe (> 90%) in 4. and moderate (60%-90%) in 5 (1 patient having 2 sites of obstruction). Risk factors for obstruction in 55 patients with single implantation procedures (10 with ohstruction: 18%) were sought. Total cross-sectiona! area of lead(s) was indexed to body surface area at implantation (INDEX). Patients with obstruction had a higher mean INDEX (7.6 ± 1.6 mm^/m^) than patients without obstruction (4.9 ± 2.0 mm^/m^); P < 0.0002). Re- ceiver-operator characteristic curves showed an INDEX > 6.6 mm^/m^ to best predict obstruction, with a sensitivity of 90% and specificity of 84%. Since pacing is lifelong, sizing of transvenous leads to the child is important to prevent obstruction and preserve venous access. (PACE 1997; 20[Pt.il:l902-1909) transvenous pacing leads, venous obstruction, venography Introduction Transvenous endocardial pacing has been suggested as the preferred method of permanent cardiac pacing for adults and for children weigh- ing more than 10 kg and without right-to-left in- tracardiac shunts.' Implantation of a reliable and durable pacing system can be performed safely and easily; however, complications associated with transvenous leads can occur. Venous ob- struction has been reported during follow-up in 31%-50% of adult patients.^"'" The incidence in children has not been established. This study as- sessed the incidence and risk factors for venous obstruction in children with transvenons pacing leads. Address fnr reprints; Robert M. Gow. MBBS, Division of Cardi- ology, The Hospital for Sick ChildrBii, 555 University Avenue. Toronto, Ontario, Canada, M5G-1X8. Fax: (416) 813-7547. Re[:eived January 5, 1996; revised March 22, 1996; accepted May 6, 1996. Methods Study Subjects Following the diagnosis of venous obstruc- tion in a single patient, a study protocol was de- signed to evaluate the incidence of venous oh- struction in the pacemaker clinic population. All patients with transvenous pacing leads who were actively followed at this institution's pacemaker clinic were eligible for enrollment. The study was approved by an institutional Research Ethics Board and Informed consent was obtained. We concurrently evaluated with echocardiography 63 of 70 eligible children who had transvenous pac- ing leads implanted between 1985 and 1993. Five patients were not included because of inadequate or incomplete echocardiographic assessments and two patients were noncompliant with follow-up. All remaining 63 available patients underwent physical examination for the presence of chest wall collateral vessels which suggested venous ob- struction. Patients with defined echocardio- graphic or clinical evidence of venous obstruction had further evaluation by venography. 1902 August 1997, Part I PACE, Vol. 20