Experimental Production of Ventricular Septal Defects

Abstract

It is apparent that much useful information about various problems concerning ventricular septal defects might be obtained if a reliable method for the production of such defects in experimental animals were available,. It is the purpose of this communication to present a technique which permits one to create defects of known size in the ventricular septum, to comment about the healing process after excision of a circular button of tissue, to record the apparent relationship of size of defect and its location upon survival and cardiac dysfunction, and to describe the resultant pathologic alterations. In other papers, changes in the cardiodynamics resulting from such defects and a method for their surgical closure will be reported. PRODUCTION OF INTERVENTRICULAR DEFECTSBefore the development of the present technique a number of other methods for the production of ventricular septal defects had been studied in this laboratory. Initially, an attempt w-as made to produce such defects under direct vision. The venous inflow to the heart was occluded and a long incision was made in the right ventricle. The septal wall was grasped with toothed forceps and a small portion of the septal myocardium was excised with scissors. The resultant small interventricular defect was then enlarged by spreading the blades of the scissors. The incision in the right ventricle was temporarily approximated by the application of a Potts ductus clamp to the edges of the incision. The obstruction of the great veins to the heart was then released and the incision in the right ventricle was closed by oversewing the Potts clamp.Seven dogs were operated upon by this method. Three of them live longer than three weeks with patent defects. These three dogs were sacrificed one, two, and four months after operation and all had small patent defects about 5-6 mm in diameter. Great dilatation of the right heart occurred in one dog immediately after the defect was made and cardiac III ensued. One dog died from a tension pneumothorax. Another died 3 weeks after operation from heart failure. In this animal tricuspid insufficiency had developed as the result of division of many chordae tendineae to the valve leaflets. Death occurred three days postoperatively in one animal from rupture of the incision in the right ventricle. In one additional dog a slightly different procedure was carried out. An incision was merely made in the septum and spread with the ~~~i~;or:ĩ nstead of excising a portion of the septum. In this case the systctie murmur at UNIV CALIFORNIA SANTA BARBARA on June 22, 2015 ang.sagepub.com Downloaded from

Experimental and Clinical Observations On the Closure of Cardiac Septal Defects

“…My associates and I were also successful in producing experimentally large defects of the ventricular septum which tended to remain widely patent over long periods of observation (8). Efforts to close them surgically resulted in the development of a method which proved quite satisfactory (9).…”

“…Efforts to close them surgically resulted in the development of a method which proved quite satisfactory (9). It entailed the passage of a tubular graft through the septum and through the mid-portion of the defect so that the tube when distended would obturate the opening between the two ventricles.…”