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The Valsalva maneuver (VM) provokes strong changes in the cardiovascular system and is therefore well suited to study the cardiac-coronary interaction in humans. In 12 patients undergoing catheterization we simultaneously recorded aortic pressure, left ventricular pressure, and intracoronary pressure (Pd) and flow velocity (U) while the patients were performing a VM. Coronary wave intensity was calculated...
Coronary angiography is limited in assessing the hemodynamic significance of a coronary lesion or the state of the coronary microcirculation. Noninvasive transthoracic (TTE) and transesophageal (TEE) Doppler echocardiography have been used to measure coronary blood flow velocity and coronary flow reserve and thus the physiology of the coronary vasculature (normal, stable or unstable lesions). A fundamental,...
Photoplethysmography (PPG) is a technique widely used to monitor volumetric blood changes induced by cardiac pulsations. Pulse oximetry uses the technique of PPG to estimate arterial oxygen saturation values(SpO2). In poorly perfused tissues, SpO2 readings may be compromised due to the poor quality of the PPG signals. We have developed a new multimode PPG measurement system which utilizes a reflectance...
Mice are now commonly used as models of human cardiovascular diseases and conditions, but it is challenging to measure blood flow velocity in small vessels such as coronary arteries. Accordingly, we have developed a method using a 2 mm diameter 20 MHz pulsed Doppler probe applied to the chest of an anesthetized mouse to measure left main coronary blood flow velocity noninvasively. We also found that...
The majority of cerebral autoregulation research has focused on the middle cerebral artery. However, many symptoms of presyncope indicate posterior cerebral hypoperfusion. To address this issue, we measured cerebrovascular reactivity, cerebral blood flow velocity and dynamic cerebral autoregulation in the middle cerebral artery and vertebral arteries during orthostatic stress to presyncope in 9 healthy...
Atherosclerotic plaques form at specific sites of the arterial tree, an observation that has led to the "geometric risk factor" hypothesis for atherogenesis. It is accepted that the location of atherosclerotic plaques is correlated with sites subjected to low abnormal values of wall shear stress (WSS), which is in turn determined by the specific geometry of the arterial segment. In particular,...
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