• distal coronary
  • iFR isolates a specific period in diastole, called the wave-free period, and uses the ratio of distal coronary pressure (Pd) to the pressure observed in the aorta (Pa) over this period. (wikipedia.org)
  • severity
  • Fractional flow reserve, a pressure derived index of stenosis severity, constitutes the best example of the current importance of physiological assessment in clinical practice. (abebooks.com)
  • Baseline characteristics, maximum inflation pressures, types of balloon catheters used, and routinely registered angiographic stenosis properties (severity, length, eccentricity, and calcification) were similar in both groups. (ahajournals.org)
  • ischemia
  • We tested the hypothesis that chronic myocardial ischemia (repetitive bouts of coronary stenosis, CS) may induce IPC mediated by different mechanisms. (ahajournals.org)
  • The vast majority of experimental studies in IPC have used a brief episodes of the IPC stimulus on a background of a normal heart with normal coronary arteries, ie, virgin ischemia. (ahajournals.org)
  • To test this hypothesis, we compared the effects of repetitive ischemia, induced by 6 episodes of 90-minute coronary stenosis and 12-hour reperfusion, with a more traditional protocol of IPC, ie, delayed or second-window IPC (SWIPC). (ahajournals.org)
  • The instantaneous wave-free ratio (iFR, sometimes referred to as the instant wave-free ratio or instant flow reserve) is a diagnostic tool used to assess whether a stenosis is causing a limitation of blood flow in coronary arteries with subsequent ischemia. (wikipedia.org)
  • The CLARIFY study was a physiological study in which iFR and FFR were compared to an independent third measure, hyperaemic stenosis resistance (HSR) which uses a combination of pressure and flow assessment to detect ischemia. (wikipedia.org)
  • lesions
  • Third, a compliant arc of normal arterial wall borders part of the lumen in the majority of coronary lesions. (ahajournals.org)
  • Methods and Results- A novel 0.014-inch dual-sensor (pressure and Doppler velocity) guidewire was used in 15 coronary lesions to obtain per-beat averages of pressure drop and velocity after an intracoronary bolus of adenosine. (ahajournals.org)
  • CTA lesions were analyzed quantitatively and area stenoses ≥ 50 % and ≥ 75 % were compared to the MPI findings. (ahajournals.org)
  • The progressive accumulation of plaque within the artery wall over decades is the setup for vulnerable plaque which, in turn, leads to heart attack and stenosis (narrowing) of the artery (known as coronary artery lesions). (wikipedia.org)
  • Circulation
  • Coronary stenosis, Imaging, Structure and Physiology has become an important reference textbook for all those interested in the assessment and treatment of diseases affecting coronary circulation. (pcronline.com)
  • However, the acceptance of FFR by cardiologists contrasts with important voids in knowledge on the basic principles of coronary physiology and of other available techniques that, as an alternative to FFR, allow a more comprehensive assessment of coronary circulation. (abebooks.com)
  • 13 We hypothesized that PC-MRI flow reserve measurements could be used to identify functionally important stenoses in the anterior epicardial arterial circulation. (ahajournals.org)
  • Cardiac stress tests compare the coronary circulation while the patient is at rest with the same patient's circulation during maximum physical exertion, showing any abnormal blood flow to the myocardium (heart muscle tissue). (wikipedia.org)
  • luminal
  • During handgrip with intracoronary nitroglycerin, the pressure-rate product again increased 33%, but relative to resting control, capillary wedge pressure fell 4 mm Hg in association with a 32% increase in luminal area of the stenosis and a 28% reduction in flow resistance (all significantly different from the response to handgrip alone: p less than .001, .01, and .005, respectively). (ahajournals.org)
  • Measurement of coronary flow reserve can be used to identify functionally important luminal narrowing of the LAD artery. (ahajournals.org)
  • proximal
  • The redistribution of thallium-201 (201Tl) after coronary vasodilation was studied in 14 dogs with a proximal stenosis of the left circumflex coronary artery that did not reduce basal flow but attenuated reactive hypermia. (ahajournals.org)
  • Methods and Results -Thirty subjects (23 men, 7 women, age 36 to 77 years) underwent MRI visualization of the left main and LAD coronary arteries as well as measurement of flow in the proximal, middle, or distal LAD both at rest and after intravenous adenosine (140 μg/kg per minute). (ahajournals.org)
  • Since patients with significant narrowing of the left main or proximal left anterior descending (LAD) coronary arteries have improved survival with coronary artery bypass grafting, 1 2 3 the reliable identification of these individuals is important. (ahajournals.org)
  • Wellens' syndrome is an electrocardiographic manifestation of critical proximal left anterior descending (LAD) coronary artery stenosis in patients with unstable angina. (wikipedia.org)
  • Fractional
  • Fractional flow reserve (FFR), coronary flow reserve (CFVR), and velocity-based indices of stenosis resistance (h-SRv) and microvascular resistance (h-MRv) at maximal hyperemia were compared. (ahajournals.org)
  • More commonly coronary pressure measurements are used as a surrogate for flow measurement and techniques include iFR and fractional flow reserve (FFR). (wikipedia.org)
  • Fractional flow reserve is defined as the pressure after (distal to) a stenosis relative to the pressure before the stenosis. (wikipedia.org)
  • invasive
  • 4 5 6 Because invasive techniques are associated with some morbidity and mortality and are relatively expensive, 7 a noninvasive method of identifying and determining the functional importance of a stenosis in the left anterior epicardial arteries of humans would have substantial clinical utility. (ahajournals.org)
  • It is a non-invasive test, is generally regarded as a safe (see below) procedure and is well tolerated by patients (apart from people who suffer from claustrophobia) The majority of scans are performed using a stress/rest protocol using adenosine as the stressor which acts to induce ischaemia in the myocardium by the coronary 'steal' phenomenon. (wikipedia.org)
  • vessel
  • Coronary stenosis located at vessel bifurcations are frequent in everyday clinical practice. (pcronline.com)
  • Relief of a stenosis by stenting aims to restore vessel patency with improvement in blood flow leading to a reduction in angina symptoms. (wikipedia.org)
  • In other words, FFR expresses the maximal flow down a vessel in the presence of a stenosis compared to the maximal flow in the hypothetical absence of the stenosis. (wikipedia.org)
  • complications
  • How to manage complications in the treatment of a resistant coronary stenosis? (pcronline.com)
  • However, if stenoses are not flow limiting, then they can be safely left alone without stenting or surgery and this help reduce patient's exposure to unnecessary procedures and potential complications. (wikipedia.org)
  • angiographic
  • Therefore, although the predictive value of these findings is low, detailed evaluation of angiographic morphology of coronary stenoses may improve patient selection and reduce complication rates of PTCA. (ahajournals.org)
  • significance
  • The functional significance of the coronary collateral vessels is a matter of continuing experimental investigation although their existence has been known for over three centuries and been documented repeatedly in man and beast over the past seven decades. (wikipedia.org)
  • lumen
  • This extremely important morphologic feature of stenoses permits transient variation in stenosis lumen diameter in response to drugs or to variation in endogenous vasomotor activity or intraluminal pressure. (ahajournals.org)
  • IVUS is of use to determine both plaque volume within the wall of the artery and/or the degree of stenosis of the artery lumen. (wikipedia.org)
  • IVUS enables accurately visualizing not only the lumen of the coronary arteries but also the atheroma (membrane/cholesterol loaded white blood cells) "hidden" within the wall. (wikipedia.org)
  • citation needed] The range of lumen stenosis locations at which myocardial infarctions occurred ranged from areas of mild dilation all the way to areas of greater than 95% stenosis. (wikipedia.org)
  • resistance
  • As a result, seemingly small changes in diameter are amplified to large changes in stenosis resistance. (ahajournals.org)
  • Simultaneous assessment of stenosis and microvascular resistance may provide a valuable tool for guidance of PCI. (ahajournals.org)
  • This was shown across a variety of stenosis severities and demonstrated that over that specific period in diastole, microcirculatory resistance was the lowest and most stable compared to the rest of the cardiac cycle. (wikipedia.org)
  • In stenoses classified as ischemic, the wave-free period provided a similar reduction in microvascular resistance as adenosine-mediated hyperaemia over the whole cardiac cycle. (wikipedia.org)
  • Measurement
  • After 15-220 minutes of observation, the dogs were killed and the hearts removed for the measurement of the activity of 201Tl and the radioactive microspheres in the normal (left anterior descending coronary artery [LAD]) and flow-restricted (left circumflex coronary artery [LCX]) regions. (ahajournals.org)