A New Technique for Production of Chronic Atrial Septal Defect in Cat without Thoracotomy

Cardiac hypertrophy resulting from pressure overload and from volume overload differ considerably in many respects. For example, pressure overload leads to concentric hypertrophy while volume overload leads to eccentric hypertrophy (1). Systolic contractile function is depressed in pressure overload hypertrophy (2) but is normal in volume overload hypertrophy (3). Studies utilizing experimentally produced pressure overload hy-pertrophied right ventricular papillary muscles of small mammals like cats (3-6) and rabbits (7, 8) have contributed considerably to the understanding of changes in myocar-dial function in cardiac hypertrophy. A surgically produced atrial septal defect in cats has been shown by Cooper et al. (3) to cause volume overload right ventricular hypertrophy which is another useful model for the study of cardiac hypertrophy. However, the surgical technique requires thoracotomy and pericardiotomy. A nonsurgical technique to create an atrial septal defect would facilitate further studies Of vol...