Clinical physiology and functional imaging
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Clin Physiol Funct Imaging · May 2021
Transcutaneous PCO2 -based dead space ventilation at submaximal exercise accurately discriminates healthy controls from patients with chronic obstructive pulmonary disease.
Increased physiological dead space ventilation (VD /VT ) at exercise reflects pulmonary gas exchange impairment and is a sensitive marker of cardio-respiratory disease. VD /VT is typically not measured during routine cardiopulmonary exercise testing (CPET) because its calculation requires arterial blood gas analysis for determination of PaCO2 . Instead, dead space ventilation is indirectly evaluated as a determinant of the ventilation (VE)/VCO2 relationship, which also depends on the PaCO2 set point. We hypothesized that VD /VT calculations based on non-invasive transcutaneous PCO2 (PtcCO2 ) measurement had better diagnostic characteristics than the VE/VCO2 slope for the discrimination of healthy subjects from patients with COPD, a common disease associated with impaired pulmonary gas exchange. ⋯ PtcCO2 -based VD /VT was the most accurate measurement to discriminate healthy controls from subjects with COPD, a chronic lung disease associated with altered pulmonary gas exchange. Non-invasive monitoring of PtcCO2 may be useful for routine CPET.
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Clin Physiol Funct Imaging · Jan 2021
Ventilatory inefficiency during graded exercise in COPD: A pragmatic approach.
The current approach to measuring ventilatory (in)efficiency (V'E -V'CO2 slope, nadir and intercept) presents critical drawbacks in the evaluation of COPD subjects, owing mainly to mechanical ventilatory constraints. Thus, we aimed to compare the current approach with a new method we have developed for ventilatory efficiency calculation. ⋯ Although requiring more complex calculations compared to the current procedure, the new approach is highly sensitive to true ventilatory/gas-exchange deterioration, even throughout more severe pulmonary lung function in COPD subjects.
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Clin Physiol Funct Imaging · May 2019
Decreased biventricular longitudinal strain in patients with systemic sclerosis is mainly caused by pulmonary hypertension and not by systemic sclerosis per se.
Patients with pulmonary arterial hypertension (PAH) due to systemic sclerosis (SSc) have high mortality. Left ventricular (LV) peak global longitudinal strain (GLS) is decreased in SSc. It is unknown whether low GLS is due to SSc or PAH. Therefore, our primary aim was to evaluate both LV and right ventricular free wall GLS (RVFW GLS) in SSc, with and without PAH, using cardiac magnetic resonance with feature tracking. Secondary aim was to relate GLS to invasive mean pulmonary arterial pressure (mPAP) and pulmonary vascular resistance (PVR). ⋯ Lower GLS is mainly determined by increased pulmonary pressure and not by SSc per se. Low LV and RVFW GLS are indicative of increased mPAP and PVR, which opens for improved non-invasive methods to select patients eligible for right heart catheterization and to monitor the effects of PAH therapy.
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Clin Physiol Funct Imaging · Mar 2019
Comparative StudyEchocardiographic right ventricular strain from multiple apical views is superior for assessment of right ventricular systolic function.
Right ventricular (RV) systolic function is an important determinant of outcome in patients with pulmonary hypertension (PH). Conventional echocardiographic measures of RV are mainly based on longitudinal contractility. Recently, measurement of RV global longitudinal strain derived from multiple windows (RVGLS) has emerged as an option but has not been well evaluated. The aim of the present study was to evaluate which echocardiographic RV function parameter correlates best with RV ejection fraction derived from cardiac magnetic resonance imaging (RVEFCMR ). ⋯ The echocardiographic RV measures, RVGLS and RVfree correlated well with RVEFCMR , whereas correlation with TAPSE, RIMP and S' was unsatisfactory. Our findings suggest that RVGLS and RVfree are the preferred echocardiographic methods for clinical practice. RVfree is easiest to perform but RVGLS could provide incremental value in selected patients.
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Clin Physiol Funct Imaging · Sep 2018
Comparative StudyRight ventricular speckle tracking assessment for differentiation of pressure- versus volume-overloaded right ventricle.
Right ventricular (RV) dysfunction may be caused by either pressure or volume overload. RV function is conventionally assessed with echocardiography using tricuspid annular plane systolic excursion (TAPSE), RV fractional area change (RVFAC), tricuspid lateral annular systolic velocity (S') and RV index of myocardial performance (RIMP). The purpose of this study was to evaluate whether RV global longitudinal strain (RVGLS) and RV-free wall strain (RV-free) could add additional information to differentiate these two causes of RV overload. ⋯ In this study, RVGLS and RV-free could more accurately discriminate RV pressure from volume overload than conventional measures. The reason could be that TAPSE and S' are unable to differentiate active deformation from passive entrainment caused by the left ventricle. The pressure group had evidence of marked RV hypertrophy despite standard functional parameters (TAPSE and S) within normal range. This would enhance the value of strain to more sensitively detect abnormal function. A cut-off value of below -16% for RVGLS and RV-free predicts RV pressure overload with high accuracy.