Further studies of hereditary patent ductus arteriosus (PDA) in the dog show the defect to have a graded phenotypic expression. A high proportion of offspring of test matings had a fully patent ductus arteriosus, while a smaller proportion had a blind diverticulum of the ductus arteriosus which communicated with the aorta. This is considered to be a forme fruste of PDA, representing incomplete closure. Approximately 50% of pups with fully patent ductus arteriosus developed signs of left heart failure, and about 15% developed severe pulmonary hypertension with right-to-left or bidirectional shunts. Genetic analysis indicated that hereditary PDA in the dog is not a simple mendelian trait. Rather, it resembles a quasi-continuous or threshold trait with a high degree of heritability. Results were analyzed using a polygenic model with two developmental thresholds. Liability to defective closure of the ductus arteriosus increased with the proportion of the genome received from dogs with PDA. Moreover, in pups which had PDA, the incidence of serious sequelae (left heart failure and severe pulmonary hypertension) increased in a parallel fashion, suggesting that an increased liability to PDA was accompanied by an increase in the severitv of the lesion. KEY WORDSductus diverticulum threshold trait heritability quasi-continuous trait left heart failure pulmonary hypertension vascular shunt • Persistent patency of the ductus arteriosus after birth (PDA) is one of the most common cardiovascular anomalies found in man (1, 2) and the dog (3-5). A number of reports of the familial occurrence of PDA have implicated genetic factors in the cause of this defect in man (6-11) but the mode of transmission and pathogenetic mechanisms involved are From the Comparative Cardiovascular Studies Unit and the Section

No abstract

Stenosis of the left ventricular outflow tract is one of the most frequent congenital cardiac anomalies in dogs. The subvalvular stenosis is described as a ring of fibrous tissue located in the left ventricular outflow tract immediately below the aortic valve. The best method of surgical treatment in dogs seems to be relief of the aortic obstruction with a ventricular aortic prosthesis. A new trileaflet valve manufactured out of polyurethane has been developed. For the conduit a woven Dacron graft has been used. In 5 male dogs a valved conduit was implanted between the apex of the left ventricle and the aorta thoracica without using hypothermia and/or cardiopulmonary bypass. Four dogs survived the surgical procedure and showed no clinical symptoms postoperatively. Blood flow through the conduit was demonstrated postoperatively by angiocardiography for a maximum of 22 days, the longest surviving time being 8 weeks. Trials for the replacement of the artificial valve in the conduit by a canine aortic allograft valve are in progress. Studies were done with the cryopreservation of fresh aortic valves. Sterilization, cryoconservation, and storage methods for the allograft are described.

No abstract

Zusammenfassung Ein vierjähriger Deutscher Schäferhund wurde wegen Gewichtsverlusts und raschen Ermüdens zur Untersuchung in die Klinik gebracht. Bei der Auskultation war ein Strömungsgeräusch im Pulmonal‐ und Aortenfeld zu hören. Im EKG ergaben sich Hinweise für eine Rechtshypertrophie (im Uhrzeigersinn drehende QRS‐Schleife in der Frontalebene und tiefe S‐Zacken in der linken unteren Brustwandableitung). Angiokardiographisch konnte eine Vena cava cranialis sinistra persistens, ein Vorhofseptumdefekt und ein Ductus‐Divertikel nachgewiesen werden. Die klinische Diagnose wurde pathologischanatomisch durch die Sektion bestätigt. Das Strömungsgeräusch wird als Folge einer relativen Pulmonalstenose durch Volumenüberlastung des rechten Ventrikels mit ausgeprägter postvalvulärer Dilatation der Pulmonalarterie interpretiert. Summary Atrial septal defect and persistent left cranial vena cava in an Alsatian dog A four‐year‐old Alsatian dog was brought to the clinic because it had lost weight and rapidly became tired. Auscultation revealed a flow murmur in the pulmonary and aortic field. The ECG gave indications of a right hypertrophy (QRS loop turned clockwise in the frontal plane and showing deep S waves in the left lower thoracic lead). The angiocardiogram showed a persistent left anterior vena cava, a defect in the atrial septum and a ductus diverticulum. The clinical diagnosis was confirmed at autopsy. The murmur is considered to have been the result of a relative pulmonary stenosis with over‐distension of the right ventricle and marked post‐valvular dilatation of the pulmonary artery. Résumé Communication interauriculaire et persistance de la veine cave supérieure gauche chez un chien berger allemand Un chien berger allemand, âgé de quatre ans, a été amené à la clinique pour examen, à cause d'une perte de poids et d'une trop grande fatigabilité. A l'auscultation, on pouvait entendre un souffle au foyer aortique et pulmonaire. L'ECG donne des indices pour une hypertrophie droite (complexe QRS se déplaçant dans le sens des aiguilles de la montre dans le plan frontal et ondes S profondes dan la dérivation thoracique inférieure gauche. L'angiocardiogramme révèle une veine cave supérieure gauche persistante, une communication interauriculaire et un diverticule du canal artériel. Le diagnostic clinique est confirmé à la pathologie et à l'anatomie après nécropsie. Le souffle est interprété comme étant la conséquence d'une sténose pulmonaire relative par surcharge du volume du ventricule droit avec dilatation post‐valvulaire prononcée de l'artère pulmonaire. Resumen Defecto del tabique interauricular y vena cava craneal izquierda persistente en un perro pastor alemán Un perro pastor alemán, de 4 años de edad, fué internado en la clínica para ser sometido a observación a causa de pérdidas ponderales y cansancio rápido. Al ser auscultado, se oía un ruido de corriente en la región pulmonar y de las aortas. En el ECG se infirieron indicios de una hipertrofia derecha (asa QRS que giraba en el sentido de las manecillas de un reloj...