Search results for "Afterload"
showing 10 items of 13 documents
Heavy vs Light Load Single-Joint Exercise Performance with Different Rest Intervals
2017
Abstract The aim of the study was to compare the effect of three distinct rest period lengths between sets of upper body single-joint exercise with different load zones and volume designed for either endurance or hypertrophy (50% or 80% of 1-RM). Sixteen trained men (20.75 ± 2.54 years; 76.35 ± 5.03 kg; 176.75 ± 3.33 cm, 24.53 ± 1.47 kg/m2) performed a test and retest of 1-RM on non-consecutive days. Forty-eight hours after load testing, the participants were randomly assigned to six sessions consisting of four sets of the triceps pull-down, combining different intensities with distinct rest periods between sets. The shorter 1 minute rest promoted a significant reduction in the total repeti…
Influence of preload and afterload on stroke volume response to low-dose dobutamine stress in patients with non-ischemic heart failure: a cardiac MR …
2011
Lack of increase in left ventricular (LV) stroke volume (SV) during low-dose dobutamine stress (LDD) is attributed to exhausted cardiac contractile reserve in failing heart. However, the role of the afterload and preload in SV changes is underestimated. The aim of the study was to investigate the effects of LDD on preload reserve and afterload in patients with non-ischemic heart failure.58 patients (age 62 years) underwent LDD (up to 20μg/kg/min) using cardiac magnetic resonance.LV-SV increased by 27% in 24 patients (p0.001) (SV+), while decreased by 19% in 22 patients (p0.001) (SV-). The LDD-to-rest reduction in preload, as defined by LV end-diastolic volume (EDV), was more pronounced in S…
Usefulness and limitations of contractile reserve evaluation in patients with low-flow, low-gradient aortic stenosis eligible for cardiac resynchroni…
2014
Aims In low-flow, low-gradient aortic stenosis (LF/LG AS), the assessment of contractile reserve (CR) by dobutamine stress echocardiography (DSE) is recommended for risk stratification and treatment strategy. However, DSE may show limitations in cases of left ventricular dyssynchrony (LVD). The impact of LVD in LF/LG AS, and the feasibility of CRT in this setting have never been evaluated. We aimed to assess: (i) the proportion of LF/LG AS patients with LVD; (ii) the influence of LVD on CR at DSE; and (iii) the effects of CRT in these patients. Methods and results Thirty consecutive patients with LF/LG AS underwent DSE with study of CR. The operative risk for aortic valve replacement (AVR) …
CRT-727 Percutaneous Balloon Atrial Septostomy for Direct Left Heart Decompression in Patients on Extra Corporeal Membrane Oxygenation
2014
Severe myocardial dysfunction and added afterload from the Extra Corporeal Membrane Oxygenation (ECMO) arterial cannula may lead to significant rise in left ventricular (LV) end-diastolic and left atrial (LA) pressures. This may result in ischemia, lower likelihood of ventricular recovery and hence
Evaluation of ventricular wall stress and cardiac function in patients with dilated cardiomyopathy
2015
Dilated cardiomyopathy is a heart disease characterized by both left ventricular dilatation and left ventricular systolic dysfunction, leading to cardiac remodeling and ultimately heart failure. We aimed to investigate the effect of dilated cardiomyopathy on the pump performance and myocardial wall mechanics using patient-specific finite element analysis. Results evinced pronounced end-systolic wall stress on left ventricular wall of patients with dilated cardiomyopathy as compared to that of normal hearts. In dilated cardiomyopathy, both end-diastolic and end-systolic pressure–volume relationships of left ventricle and right ventricle were shifted to the right compared to controls, sugges…
Extreme Pulsus Alternans with P Wave Alternans in a Child
2002
Pulsus alternans was observed in a child with left ventricular dysfunction secondary to systemic hypertension. The Echo-Doppler of supravalvular aorta and a simultaneous electrocardiographic trace (ECG) clearly demonstrated the mechanism of an apparent abrupt halving of pulse frequency compared with the ECG, similar to an electromechanical dissociation 2: 1. Besides the extreme pulsus alternans, a P wave and a PP cycle length change were also observed. Both mechanical and electrical alternans disappeared with afterload reduction by nitroprusside treatment.
I-125 seed calibration using the SeedSelectron(®) afterloader: a practical solution to fulfill AAPM-ESTRO recommendations.
2012
Purpose SeedSelectron® v1.26b (Nucletron BV, The Netherlands) is an afterloader system used in prostate interstitial permanent brachytherapy with I-125 selectSeed seeds. It contains a diode array to assay all implanted seeds. Only one or two seeds can be extracted during the surgical procedure and assayed using a well chamber to check the manufacturer air-kerma strength (SK) and to calibrate the diode array. Therefore, it is not feasible to assay 5–10% seeds as required by the AAPM-ESTRO. In this study, we present a practical solution of the SeedSelectron® users to fulfill the AAPM- ESTRO recommendations. Material and methods The method is based on: a) the SourceCheck® well ionization chamb…
Sublingual administration of captopril versus nitroglycerin in patients with severe congestive heart failure.
1990
Angiotensin-converting enzyme inhibition has proven to be a successful approach for the long-term treatment of patients with congestive heart failure. This investigation compared the acute hemodynamic changes after sublingual administration of the angiotensin-converting enzyme inhibitor captopril with those after nitroglycerin. A total of 24 patients with severe left heart failure (New York Heart Association classes III and IV) were given 25 mg captopril and 0.8 mg nitroglycerin sublingually in this randomized, cross-over study. Hemodynamic monitoring revealed a clear improvement in pre- and afterload parameters for both drugs (P less than 0.01 and P less than 0.001), while captopril induce…
Relative sensitivity of four noninvasive methods in assessing systolic cardiovascular effects of isoproterenol in healthy volunteers.
1992
Study objective The study was performed to evaluate the relative sensitivity of various noninvasive methods to detect and describe the systolic cardiovascular effects of stepwise increasing doses of isoproterenol: two-dimensional left ventricular echocardiography (main variable, ejection fraction), ACVF (attenuation compensated volume flow)–dual-beam Doppler echoaortography (time-averaged mean velocity), electrical impedance cardiography [(dZ/dtmax)/RZ index], and systolic time intervals from mechanocar-diography (PEP and QS2c). Methods Isoproterenol was administered by constant rate intravenous infusion in consecutive steps of 0.1, 0.2, 0.4, 0.75, and 1.5 µg/min (each for 15 minutes). Sali…
Computational fluid dynamics simulation to evaluate aortic coarctation gradient with contrast-enhanced CT
2014
Coarctation of aorta (CoA) is a narrowing of the aorta leading to a pressure gradient (Delta P) across the coarctation, increased afterload and reduced peripheral perfusion pressures. Indication to invasive treatment is based on values of maximal (systolic) trans-coarctation Delta P. A computational fluid dynamic (CFD) approach is herein presented for the non-invasive haemodynamic assessment of Delta P across CoA. Patient-specific CFD simulations were created from contrast-enhanced computed tomography (CT) and appropriate flow boundary conditions. Computed Delta P was validated with invasive intravascular trans-CoA pressure measurements. Haemodynamic indices, including pressure loss coeffic…