Physiological reports
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Physiological reports · Oct 2016
Minimally invasive beat-by-beat monitoring of cardiac power in normal hearts and during acute ventricular dysfunction.
Cardiac power, the product of aortic flow and blood pressure, appears to be a fundamental cardiovascular parameter. The simplified version named cardiac power output (CPO), calculated as the product of cardiac output (CO) in L/min and mean arterial pressure (MAP) in mmHg divided by 451, has shown great ability to predict outcome in a broad spectrum of cardiac disease. Beat-by-beat evaluation of cardiac power (PWR) therefore appears to be a possibly valuable addition when monitoring circulatory unstable patients, providing parameters of overall cardiovascular function. ⋯ We found that the uPWR-integral overestimated compared to the ttPWR-integral by about 10% (P < 0.001) in both normal hearts and during ventricular dysfunction. Bland-Altman limits of agreement were at +0.060 and -0.054 J, without increasing spread over the range. In conclusion we find that the minimally invasive system follows its invasive counterpart, and is ready for clinical research of cardiac power parameters.
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Physiological reports · Sep 2016
A critical appraisal of transpulmonary and diastolic pressure gradients.
Pulmonary hypertension (PH) resulting from left heart failure is an increasingly recognized clinical entity. To distinguish isolated postcapillary PH from combined post- and precapillary PH, the use of a diastolic pressure gradient (DPG = diastolic Pulmonary Artery Pressure - Pulmonary Arterial Wedge Pressure, dPAP - PAWP) has been advocated over the transpulmonary pressure gradient (TPG = mean Pulmonary Artery Pressure - PAWP, mPAP - PAWP) since DPG was suggested to be independent of cardiac output (CO) and only slightly related to PAWP, while TPG depends on both. We quantitatively derived and compared the DPG and TPG Using right heart catheterization data (n = 1054), we determined systolic pulmonary artery pressure (sPAP), dPAP and mPAP, PAWP, and CO From this data, we derived TPG and DPG and tested their dependence on PAWP and CO We found that dPAP and sPAP are proportional with mPAP over a wide range of PAWP (1-31 mmHg), with dPAP = 0.62mPAP and sPAP = 1.61mPAP As a consequence, TPG and DPG are equally dependent on PAWP: TPG = mPAP - PAWP, and DPG = 0.62mPAP - PAWP Furthermore, we showed that both TPG and DPG depend on CO The absolute increase in DPG with CO is 62% of the TPG increase with CO, but the relative dependence is the same. Both TPG and DPG depend on PAWP and CO Thus, in principle, there are no major advantages for using DPG to distinguish postcapillary pulmonary hypertension from combined post- and precapillary pulmonary hypertension.
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Physiological reports · Jul 2016
Carotid artery longitudinal wall motion is associated with local blood velocity and left ventricular rotational, but not longitudinal, mechanics.
Recent studies have identified a predictable movement pattern of the common carotid artery wall in the longitudinal direction. While there is evidence that the magnitude of this carotid artery longitudinal wall motion (CALM) is sensitive to cardiovascular health status, little is known about the determinants of CALM The purpose of this integrative study was to evaluate the contribution of left ventricular (LV) cardiac motion and local blood velocity to CALM Simultaneous ultrasound measurements of CALM, common carotid artery mean blood velocity (MBV), and left ventricular motion were performed in ten young, healthy individuals (6 males; 22 ± 1 years). Peak anterograde CALM occurred at a similar time as peak MBV (18.57 ± 3.98% vs. 18.53 ± 2.81% cardiac cycle; t-test: P = 0.94; ICC: 0.79, P < 0.01). ⋯ The association between basal rotation and retrograde CALM was further supported by strong correlations between their peak magnitudes (r = -0.70, P = 0.02), whereas the magnitude of septal longitudinal displacement was not associated with peak CALM (r = 0.11, P = 0.77). These results suggest that the rotational mechanical movement of the LV base may be closely associated with longitudinal mechanics in the carotid artery. This finding may have important implications for interpreting the complex relationship between ventricular and vascular function.
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Physiological reports · Jun 2016
Adverse ventricular-ventricular interactions in right ventricular pressure load: Insights from pediatric pulmonary hypertension versus pulmonary stenosis.
Right ventricular (RV) pressure overload has a vastly different clinical course in children with idiopathic pulmonary arterial hypertension (iPAH) than in children with pulmonary stenosis (PS). While RV function is well recognized as a key prognostic factor in iPAH, adverse ventricular-ventricular interactions and LV dysfunction are less well characterized and the pathophysiology is incompletely understood. We compared ventricular-ventricular interactions as hypothesized drivers of biventricular dysfunction in pediatric iPAH versus PS Eighteen iPAH, 16 PS patients and 18 age- and size-matched controls were retrospectively studied. ⋯ Prolonged RVFW thickening, prolonged RVFW isovolumetric times, and profound septal dyskinesia are associated with interventricular mechanical discoordination and decreased early LV filling in pediatric iPAH much more than PS These adverse mechanics affect systolic and diastolic biventricular efficiency in iPAH and may form the basis for worse clinical outcomes. We used clinically derived data to study the pathophysiology of ventricular-ventricular interactions in right ventricular pressure overload, demonstrating distinct differences between pediatric pulmonary arterial hypertension (iPAH) and pulmonary stenosis (PS). Altered timing of right ventricular free wall contraction and profound septal dyskinesia are associated with interventricular mechanical discoordination and decreased early LV filling in iPAH much more than PS These adverse mechanics affect systolic and diastolic biventricular efficiency, independent of right ventricular systolic pressure.
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Physiological reports · May 2016
Repeatability of vascular responsiveness measures derived from near-infrared spectroscopy.
Near-infrared spectroscopy (NIRS)-derived measures of tissue oxygen saturation (StO2) have been recently shown to significantly correlate with the widely used method for noninvasively assessing vascular endothelial function, flow-mediated dilation (FMD). The purpose of this study was to examine the intraday and interday reliability of the reperfusion slope of StO2 (slope 2 StO2) and compare it to FMD Ultrasound-derived FMD was quantified following 5 min of distal cuff occlusion of the popliteal artery in nine healthy young men (26 ± 3 years). An FMD test was performed each of 4 days, with a fifth involving three tests. ⋯ Repeatability of slope 2 StO2 was better than %FMD for both intraday (0.43 and 5.65, respectively) and interday (0.48 and 4.82, respectively) comparisons; approximately 30% of mean values for slope 2 StO2 could be attributed to measurement error, whereas 100% of mean FMD could be for both intraday and interday comparisons. Similarly, ICC and CV values indicated stronger reliability of slope 2 StO2 compared to %FMD for both intraday (ICC 0.92 and 0.36, respectively; CV 9 ± 4% and 44 ± 24%, respectively) and interday (ICC 0.94 and 0.25, respectively; CV 14 ± 5% and 40 ± 22%, respectively) comparisons. In conclusion, NIRS-derived slope 2 StO2 can be used as a reliable measure of vascular reactivity.