Catheterization Laboratory Study: Acute Responses in Diastolic Heart Failure

1. Research question: What is the response of the heart's pumping function to changes in
heart chamber pressures?

2. Experimental design: Patients undergoing routine cardiac catheterization will be
studied. A thermodilution pulmonary artery catheter will be inserted through a venous
sheath and threaded into the pulmonary artery. After several minutes of quiet rest,
baseline hemodynamics will be obtained, including a determination of cardiac output
using thermodilution techniques and 30 seconds of pressure recordings from the left
ventricle and proximal aorta. In addition, a brief echocardiogram will be performed, to
determine ejection fraction and indices of diastolic filling. Finally, arterial
tonometry will be obtained in quick succession from the brachial, radial, femoral, and
carotid arteries. Following the collection of baseline data, a bolus and infusion of
nesiritide will be started. After 10 minutes of nesiritide infusion, with the drug still
infusing, a full set of invasive hemodynamics will again be obtained, as well as brief
echocardiographic and arterial tonometry examinations.