The theme of Dr. Ross, Jr’s lecture was how prior laboratory research often forms the basis for later clinical and laboratory research, even though the connection often is not cited or recognized. For example, Oswald Avery described DNA as genetic transforming factor in 1943, but his work was not cited in the Watson and Crick paper of 1953 for which they won the Nobel prize in 1962.

According to Dr. Ross, Jr. the past 50 years have witnessed a remarkable transformation of cardiovascular science and medicine. In the mid-1950s, Dr. Ross, Jr. participated with Dr. Alfred Blaylock at Johns Hopkins University School of Medicine on several Blaylock-Taussig operations on children with tetralogy of Fallot. Dr. Ross, Jr. then went to the then National Heart Institute in Bethesda, Maryland for research and training in the surgery clinic. At the time right heart catheterization was widely used but left heart catheterization was a new procedure with many hazardous approaches. The safest method was the transbronchial approach, which involved passing a needle through a bronchoscope to puncture the left atrium.

Dr. Ross, Jr. began dog studies to develop a method to reach the left heart by puncturing the inter-atrial septum. He devised a long needle with a curved tip, a reversed bevel, and an arrow shaped handle through which a small catheter could be passed. He was able to puncture the left atrium through the septum; pressure could be measured in the left atrium and left ventricle (LV) using the catheter. Left heart angiography also could be performed by contrast injection through the transseptal needle into the left atrium. The first transseptal left heart catheterization in a human patient occurred in 1958 in a man with mitral regurgitation. In 1960, Dr. Ross published his experience with the first 130 patients who had this procedure, all without complications. In 1960, the transseptal method was modified to use the percutaneous Seldinger approach with a larger taper-tipped catheter, which allowed left ventriculography to be performed.

In 1962, Dr. Ross, Jr. became a section head in charge of the catheterization laboratory at the National Heart Institute. There, he studied ventricular function in experimental animals, particularly the roles of afterload, preload, and inotropic state in normal and failing hearts. Among these studies was one that demonstrated the effects of sudden aortic pressure elevation during diastole in the dog heart, which altered only the afterload. There was an inverse relation between the afterload and stroke volume, from which the force velocity relation of the whole heart was calculated. Pressure volume loops provide a convenient way of looking at the responses of the left ventricular pressure-volume relation to changes in afterload.

In other experiments in which preload was allowed to vary, marked volume loading was used to produce a very high end-diastolic pressure and volume, and the limit of preload reserve was reached. In the absence of preload reserve, when the afterload is further increased, in beat 4 the stroke volume falls. These studies led to a clinical investigation in patients undergoing transseptal left heart catheterization. In patients with or without left ventricular dysfunction the afterload was progressively increased by graded infusions of angiotensin II. As the afterload increased the stroke volume increased in normal patients, whereas the stroke volume stayed the same in patients with cardiac dysfunction. When the stroke volume index was plotted against the left ventricular systolic pressure, the stroke volume rose in the normal patients but abruptly fell in patients with cardiac dysfunction. This was the first investigation to demonstrate enhanced sensitivity of the failing human LV to increased afterload.

Ongoing clinical investigations led to the concept of afterload mismatch with preload reserve, which can be defined as inability of the LV to maintain the stroke volume with increased afterload due to high arterial pressure, when preload reserve is fully utilized. In the failing dilated LV, it is defined as the inability of the LV to maintain the stroke volume with increased afterload due to high wall stress at rest, even at normal arterial pressure (Wst=P.r/Wth).

In 1968, Dr. Ross, Jr. moved to the University of California San Diego Medical School to become chief of Cardiology and director of a Myocardial Infarction (MI) Research Unit awarded by the NIH. Here he studied the effects of coronary reperfusion after long coronary occlusion. A study of reperfusion in dogs showed a reduction in infarct size at one week after occlusion. In 1986, a landmark trial in Italy proved that reperfusion by thrombolysis with streptokinase could be lifesaving in patients with MI. These and other studies proved that reperfusion reduces infarct size, leading to widespread use of thrombolysis and PTCA to treat acute MI.

Dr. Ross, Jr. showcased some of the research of Japanese cardiologists who formerly trained with him. Dr. Sasayama studied the development of LV hypertrophy, establishing that compensatory hypertrophy can be associated with normal myocardial contractility and that the end-systolic pressure-diameter relation is not reliable as a measure of contractility in the presence of chronic heart disease. In 1978, Dr. Tomoike demonstrated in dogs that exercise can produce marked regional myocardial dysfunction in the presence of severe coronary stenosis. In 1983, Dr. Matsuzaki showed that reperfusion corrected the effects of prolonged ischemia in dogs. In a 1992 experiment, Dr. Miura demonstrated a marked negative inotropic effect as heart rate is reduced in exercising dogs. Dr. Kambayashi showed that beta adrenergic stimulation enhances the force-frequency relation in conscious dogs. Thus, at rest and at exercise, both high-frequency and beta adrenergic stimulation are needed to achieve maximum contractility.

The major determinants of myocardial contractility are beta adrenergic stimulation, length-dependent activation, which plays a role in the Frank-Starling mechanism, the force-frequency relation, and beta adrenergic regulation. This regulation is lost in patients and animals with heart failure.

In 2002, the genetic defect in cardiomyopathic hamsters was found to be a mutation in the delta-sarcoglycan (d-SG) gene. The d-SG protein is an important component of the transmembrane dystrophin-dystroglycan complex in normal cardiac myocytes. Dr. Ross, Jr. and others developed a method for high efficiency gene transfer via the coronary arteries. Delivery of an adenoviral vector containing the missing gene to cardiomyopathic hamsters resulted in good d-SG protein expression at 3 weeks and mildly improved cardiac function. Other researchers obtained good results using a different vector directly injected into the LV wall.

In 2005, researchers delivered a new AAV serotype ape vector containing the d-SG gene into neonatal and 6-week old cardiomyopathic hamsters, which completely prevented the detrimental effects of the mutation in animals followed for up to one year. In an ongoing study using a different vector to deliver the d-SG gene, preliminary results indicate that the progression of an established dilated cardiomyopathy can be entirely arrested by gene therapy (Figure 2). According to Dr. Ross, Jr., these findings will be relevant for the future treatment of cardiomyopathies in humans.

Dr. Ross, Jr. concluded that he is very optimistic about the future of cardiovascular research and medicine. Despite initial clinical difficulties, cardiac gene therapy clearly can be effective in animals. Dr. Ross, Jr. is currently an advisor in a phase I clinical trial of gene therapy for heart failure. The development of embryonic stem cells will have multiple future applications. Other promising avenues include the identification of small peptides, such as growth factors and growth factor inhibitors, development of agents to inhibit specific signaling pathways, manipulation of micro-RNAs, and tissue engineering.