Cardiovascular Function Laboratory

The Cardiovascular Function sub-unit of the Cardiothoracic Research Laboratory is devoted to the study of basic cardiopulmonary physiology in its application to clinically relevant problems. Chronically instrumented conscious animals are generally used in conjunction with a wide variety of state-of-the-art data collection and analysis techniques. Study methods include pulse transient sonmicrometry for dimensional analysis of global and regional ventricular geometry, high fidelity micromanometry, Doppler measurement of aortic, pulmonary, and coronary blood flow, 2-dimensional echocardiography for measuring left ventricular wall mass, color flow echocardiographic assessment of valvular lesions, 3-dimensional echocardiography, cardiac catheterization for coronary sinus and coronary artery instrumentation, on-line venous and arterial oxygen saturation for renal time oxygen consumption analysis, and ventricular thermo dilution calorimetry.

 

The implantable devices are placed on the heart under sterile, operating room conditions and the chest wall through a percutaneous access device that allows infection-free survival for several months. The long-term nature of the instrumentation permits study of a wide variety of chronic heart disease topics, such as ventricular adaptation to valvular disease. High fidelity micromanometer tipped catheters are passed via implanted tubes into the aorta, pleural space, and left and right ventricles, and other electronic leads are connected directly to computerized data acquisition systems. The on-line digital system has the capability to simultaneously record up to 16 channels of dimension, flow, pressure, temperature and oxygen saturation data for subsequent computer analysis.

 

This methodology has facilitated the development of several physiologic concepts for quantitative assessment of ventricular function, including the stroke work-end diastolic volume relationship and the concept of myocardial metabolic-to-mechanical energy transfer. These models have been applied to the study of cardiopulmonary resuscitation, cardiopulmonary interactions, functional and metabolic responses to ischemia, left ventricular adaptation to valvular disease, intra-aortic balloon pumping, and myocardial protection. Moreover, they have been successfully applied in humans after cardiac valve replacement or coronary artery bypass grafting in studies of myocardial preservation, cardiopulmonary interaction, and early endotracheal extubation.

 

The efforts of the laboratory are now being directed toward: 1) delineating the complex systolic mechanics of both the normal right ventricle and the right ventricle failing due to pressure overload, tricuspid regurgitation, or cardiomyopathy; 2) formulating a unifying concept to explain the cardiac hyper tropic response to stresses such as left ventricular volume overload, growth and chronic tachycardia; 3) development of non-invasive, load insensitive and a clinically applicable means to quantify left ventricular isotropic state; 4) better models of aortic impedance analysis; and 5) improvement of left ventricular systolic function by viral gene transfer to the myocardium or myocardial implantation of genetically engineered myocytes. A full-time electrical engineer, James Davis, Ph.D., is an independent investigator involved in studies of conductance volumetry, simulation of aortic impedance, 3-dimensional computer driven sonmicrometry, and developing data analysis software. The ultimate goal of this laboratory is the application of new physiologic principles to clinically relevant problems in order to enhance the care of patients with cardiac disease.

 

For any additional information, please feel free to contact Shu Lin, M.D., PhD.