Heart and Blood Pressure Study: The Effect of Aortic Impedance on Myocardial Relaxation

Does dilation of blood vessels (vasodilation), which decreases aortic stiffness, have a greater effect on heart myocardium relaxation (diastole) than vasodilation which affects mean pressure equally without improving aortic stiffness?

60 subjects, 30 with hypertension and 30 without will attend two visits to the GCRC. At each visit, pulsatile hemodynamics (by using tonometry-a non-invasive means to obtain arterial pressure tracings) and Doppler tissue imaging relaxation velocity (a measurement of myocardial relaxation obtained by echocardiography) data will be collected before and after administration of vasodilator medication. At the first visit, each patient will receive an oral dose of the vasodilator hydralazine (does not effect aortic stiffness), and at the second visit each patient will receive intravenous nesiritide (does effect aortic stiffness). The relationship between timing of the reflected pulse wave and myocardial relaxation velocity will be studied at baseline and following administration of each vasodilator to determine if changing aortic stiffness has an impact on myocardial relaxation.

Inclusion Criteria: Subjects over the age of 65 Exclusion Criteria: Have known or suspected coronary artery disease Have known or suspected left ventricular dysfunction Have significant valvular, infiltrative, pericardial, or congenital heart disease Have a resting systolic blood pressure < 100 mmHg Have had an adverse reaction to nesiritide or hydralazine Have a serum creatinine > 2 mg/dl at Visit 1

Sweitzer NK, Hetzel SJ, Skalski J, Velez M, Eggleston K, Mitchell GF. Left ventricular responses to acute changes in late systolic pressure augmentation in older adults. Am J Hypertens. 2013 Jul;26(7):866-71. doi: 10.1093/ajh/hpt043. Epub 2013 Mar 28.