The electrocardiograms of17patients with Ebstein's anomaly of the tricuspid valve were analysed. Right bundle-branch block or Wolff-Parkinson-White syndrome (WPW) was found in the majority of patients, but there were several unusual electrocardiographic changes, including ventricular pre-excitation with normal PR interval (2 patients) and incomplete right bundlebranch block with broad Q waves suggesting inferior wall infarction (i patient). The mechanisms and clinical importance of these findings are discussed.

Electrocardiographic changes have an impor-tant diagnostic contributionin Ebstein's anomaly of the tricuspid valve. Right bundlebranch block is found in 70-80 per cent of patients (Vacca, Bussmann, and Mudd, I958; Schiebler et al., i959b; Genton and Blount, I967), usually with bizarre splintering of the QRS complex and low voltage in right prae-cordial leads. The intraventricular conduction defect is frequently associated with signs of right atrial overload and a prolonged PRinterval. Ebstein's anomaly is also the most common cardiac malformation in children with the Wolff-Parkinson-White syndrome (Schiebler et al., i959a, b). Among our patients with Ebstein's anomaly we have recently observed some unusual electrocardiographic findings which initially suggested a different diagnosis and/or the: presence of additional complications. The electrocardiograms of these patients are pre-sented in this paper.