Left Ventricular Ejection Time Research Articles

Motorized adaptive compression system for enhancing venous return: A feasibility study on healthy individuals

Notwithstanding the extensive use of conventional compression devices in managing venous disorders, these modalities have shortages that diminish their treatment efficacy and lessen patient adherence to therapy. The purpose of this study was to develop an improved compression system that eliminates the flaws of the existing devices. A motorized bandage was designed that takes advantage of continuous feedback from force-sensing resistors to apply reproducible, controlled pressure on the lower extremities. The performance of the device in enhancing venous return was explored in a pilot test on 11 healthy participants, wherein graded lower body negative pressure was employed as a surrogate of passive standing. Each subject underwent two experiments; with and without pressure application over the calves. A two-way repeated-measures analysis of variance revealed a significant difference in the mean hemodynamic responses when the compression bandage was in action (p < .05). Specifically, a meaningful increase was observed in mean arterial pressure by 5%, diastolic blood pressure by 8% and left ventricular ejection time by 4%; and a significant decrease of 5% and 6% was noticed in heart rate and pulse pressure, respectively. These results demonstrate the capability of the designed system in attenuating the imposed orthostatic stress on cardiovascular system.

Carotid Arterial Pulse Waveform Measurements Using Fiber Bragg Grating Pulse Probe.

Arterial pulse is an established source of information for the clinical assessment of cardiovascular health. The central aortic pressure is known to be a better predictor of cardiovascular status than the peripheral pressure. The carotid arterial pulse is considered to be the best indicator of the central aortic pressure. The present work deals with the development of a novel noninvasive probe based on fiber Bragg grating (FBG) sensor for the real-time acquisition of the pulse waveform in the carotid arterial site. The fiber Bragg grating pulse probe (FBGPP) developed is used to obtain the carotid arterial pulse waveform (CAPW) of individual subjects, in the form of beat-to-beat carotid pulse. The FBGPP developed comprises of an elastic rubber diaphragm that comes into contact with the skin below, which the carotid artery is pulsating, creating strain variations over it. Effectively, the carotid arterial pulse is tranduced into the strain variations over a rubber diaphragm, which is acquired by the FBG sensor bonded over it. The FBGPP is designed such that the positioning and the access for the device to the carotid arterial site can be carried out with ease. Furthermore, the recorded CAPW is subjected to the pulse wave analysis in order to evaluate vital cardiovascular parameters like heart rate, left ventricular ejection time, carotid augmentation index, and ejection duration index, which are indicators of the cardiac health of the subject and the performance of the heart. Also, the linearity between these cardiovascular parameters is explored for a sample size of 55.

Combined Seismo- and Gyro-Cardiography: A More Comprehensive Evaluation of Heart-Induced Chest Vibrations.

This paper reports on the combined analysis of seismocardiogram (SCG) and gyrocardiogram (GCG) recordings. An inertial measurement unit (IMU) consisting of a three-axis micro-electromechanical (MEMS) accelerometer and a three-axis MEMS gyroscope is used to record heart-induced mechanical vibrations from the chest wall of the subjects. An electrocardiogram and an impedance cardiogram (ICG) sensor are also used as references for segmenting the cardiac cycles and recording the aortic valve opening and closure (AO and AC) events, respectively. A simplified model is proposed to explain the mechanical coupling of the chest wall to the IMU. Correlations and time differences are analyzed for the annotation of GCG and its first derivative with respect to ICG and SCG as references. Experimental results indicate a precise identification of systolic points such as the AO and AC events. The left ventricular ejection time and pre-ejection period metrics calculated from gyroscope recordings are also shown to accurately track their corresponding trends acquired from ICG signals. Waveform similarity analyses indicate that the first derivative of GCG has a better similarity with SCG than the GCG signal itself. Experimental results also suggest that interdevice differences in GCG recordings would need to be addressed before this technology can gain widespread application.

Central diastolic pressure exponential decay constant and subendocardial flow supply.

Central diastolic pressure exponential decay constant and subendocardial flow supply.

Frequency-dependent effects of omecamtiv mecarbil on cell shortening of isolated canine ventricular cardiomyocytes.

Omecamtiv mecarbil (OM) is a myosin activator agent developed for the treatment of heart failure. OM was reported to increase left ventricular ejection fraction and systolic ejection time, but little is known about the effect of heart rate on the action of OM. The present study, therefore, was designed to investigate the effects of OM on unloaded cell shortening and intracellular Ca2+ ([Ca2+]i) transients as a function of the pacing frequency. Isolated cardiomyocytes were stimulated at various frequencies under steady-state conditions. Cell length was monitored by an optical edge detector and changes in [Ca2+]i were followed using the Ca2+-sensitive dye Fura-2. At the pacing frequency of 1Hz, OM (1-10μM) significantly decreased both diastolic and systolic cell length, however, fractional shortening was augmented only by 1μM OM. Time to peak tension and time of 90% relaxation were progressively increased by OM. At the frequency of 2Hz, diastolic cell length was reduced by 10μM OM to a larger extent than systolic cell length, resulting in a significantly decreased fractional shortening under these conditions. OM had no effect on the parameters of the [Ca2+]i transient at any pacing frequency. The results suggest that supratherapeutic concentrations of OM may decrease rather than increase the force of cardiac contraction especially in tachycardic patients.

The effect of exercises on left ventricular systolic and diastolic heart function in sedentary women: Step-aerobic vs core exercises

The purpose of this study is to investigate the effect of 16 weeks step-aerobic exercises and core exercises on left ventricular structure and function with some physiological parameters in sedentary women. MethodsTo achieve the purpose of this study, a total of 45 volunteers including (step-aerobic group (SAG, n = 25), core exercise group (CEG, n = 20) were selected as participants. Two different exercises were applied for 4 days a week, throughout 16 weeks, within 60 minutes for each exercise with the intensity of heart rate (HR) 60-70 percent. The HR was measured using a heart rate monitor for each subject. The physical, biochemical and echocardiographic characteristics of the women were measured before and after the exercise. ResultsDuring the exercise periods, there were a meaningful decrease in the body weight, BMI, value of waist region and hip circumference of the women in both intervention groups as well as in the values of HR, DBP, SBP (p < 0,05). In addition, serum homocysteine (Hcy) and high-sensitivity C-reactive protein (Hs-CRP) levels decreased and the VO2max and left ventricular diastolic end-diastolic dimension increased in both SAG and CEG (p < 0.05). The left ventricular diastolic functions of the SAG improved more than CEG. Left ventricular systolic ejection time and fractional shortening meaningfully improved in both SAG and CEG (p < 0.01). Conclusion16 weeks of step-aerobic and core exercise showed significant changes of inflammatory and lipid markers with cardiac dimensions and had favorable effects on both left ventricular systolic function. Left ventricular diastolic function had more improved in SAG than the CEG.

Left ventricular ejection time is an independent predictor of incident heart failure in a community-based cohort.

Systolic time intervals change in the progress of cardiac dysfunction. The usefulness of left ventricular ejection time (LVET) to predict cardiovascular morbidity, however, is unknown. We studied middle-aged African-Americans from one of four cohorts of the Atherosclerosis Risk in Communities study (Jackson cohort, n=1980) who underwent echocardiography between 1993 and 1995. Left ventricular ejection time was measured by pulsed-wave Doppler of the left ventricular outflow tract and related to outcomes. A shorter LVET was associated with younger age, male sex, higher diastolic blood pressure, higher proportion of diabetes, higher heart rate, higher blood glucose levels and worse fractional shortening. During a median follow-up of 17.6 years, 384 (19%) had incident heart failure (HF), 158 (8%) had a myocardial infarction, and 587 (30%) died. In univariable analysis, a lower LVET was significantly associated with increased risk of all events (P<0.05 for all). However, after multivariable adjustment for age, sex, hypertension, diabetes, body mass index, heart rate, systolic and diastolic blood pressure, fractional shortening and left atrial diameter, LVET remained an independent predictor only of incident HF [hazard ratio 1.07 (1.02-1.14), P=0.010 per 10 ms decrease]. In addition, LVET provided incremental prognostic information to the known risk factors included in the Framingham risk score, in regard to predicting all outcomes except for myocardial infarction. Left ventricular ejection time is an independent predictor of incident HF in a community-based cohort and provides incremental prognostic information on the risk of future HF and death when added to known risk prediction models.

OP.7B.11] DETERMINANTS OF PULSE PRESSURE AMPLIFICATION IN DRUG NAÏVE HYPERTENSIVE PATIENTS

Objective: Normally there is an amplification of the pressure pulse wave from the large arteries to the smaller conduit arteries and this can be understood as a “gradual widening” of the pulse pressure as it travels distally. This is known as pulse pressure amplification and is defined as the peripheral pulse pressure/central pulse pressure ratio. Of course aging is correlated with PPA but few studies have been conducted to assess its correlations with peripheral arterial resistance. The aim of the present study was to find determinants of PPA in drug naïve hypertensive patients to get insights of this phenomenon. Design and method: We recruited 87 drug naïve (mean age = 52.2 ± 12.5) 55 females, newly diagnosed hypertensive patients that visited the hypertension clinic of a tertiary hospital. Central systolic aortic BP (CSBP), Central diastolic BP (CDBP) was assessed by applanation tonometry and PWV was measured by Sphygmocor (Atcor Medical) and clinic SBP and DBP were measured according to international guidelines. Hemodynamics were assessed by impendance cardiography (ICG) by means of the Cardioscreen 2000 rheocardiographic system. The PPA ratio was defined as the peripheral pulse pressure/central pulse pressure. We used Pearson's r correlation to identify significant correlations of PPA and measured parameters and used multivariate regression analysis to identify independent determinants of PPA. Results: PPA was significantly correlated with age, bmi, gender, heart rate, urea, potassium, augmentation index, velocity index (VI), acceleration index (AI), left ventricular ejection time (LVET), systolic time ratio index (STRI), Ejection time index (ETI), left stroke work index (LSWI). In the regression model heart rate (β = 0.41, p < 0.001) and augmentation index (β = −0.71, p < 0.001) were the two significant determinants of PPA accounting for 77.4% of its variability. Conclusions: PPA is determined by heart rate and thus sympathetic nervous system amplification, and also the augmentation index which is well known marker of arterial stiffness. Overall, these two markers eliminate all other hemodynamic markers as determinants of PPA.

Role of peripheral vascular resistance as an indicator of cardiovascular abnormalities in patients with Parkinson's disease.

The aim of this study was to evaluate cardiovascular autonomic modulation in response to an orthostatic stress in healthy subjects and Parkinson's disease (PD). The study included 47 controls and 56 PD patients divided into groups (vasoconstrictor PD, vasodilator PD, control) according to vasodilation/vasoconstriction response during 70° head up tilt test. Using impedance cardiography (ICG) and electrocardiography (ECG) we measured stroke volume, cardiac output, left ventricular work index, left ventricular ejection time, acceleration index, index of contractility, Heather index, thoracic fluid content, total peripheral resistance, total arterial compliance. We also analyzed heart rate variability (HRV), using spectral analysis and continuous blood pressure (contBP). At rest, the vasodilator PD group showed significantly higher values of total peripheral resistance and lower values of stroke volume and cardiac output, compared to the vasoconstrictor PD and the control groups. A post-tilt drop in ∆ (change rest - tilt) systolic blood pressure, ∆mean blood pressure, ∆total peripheral resistance and ∆Heather index, and a significantly lower increase in ∆diastolic blood pressure was observed in subjects from the vasodilator PD group compared to the vasoconstrictor PD and the control groups. No statistically significant differences were observed for HRV parameters between the vasoconstrictor and vasodilator PD groups, P>.05. Longer duration and higher disease stage of PD correlated with a reduction in post-tilt systolic blood pressure changes in vasodilator group. Positive inotropy of the cardiac muscle represents a significant factor preventing orthostatic hypotension in PD subjects with a concurrent drop in peripheral vascular resistance during orthostatic stress.

Moderate exercise based on artificial gravity preserves orthostatic tolerance and exercise capacity during short-term head-down bed rest.

Numerous countermeasures have been proposed to minimize microgravity-induced physical deconditioning, but their benefits are limited. The present study aimed to investigate whether personalized aerobic exercise based on artificial gravity (AG) mitigates multisystem physical deconditioning. Fourteen men were assigned to the control group (n=6) and the countermeasure group (CM, n=8). Subjects in the CM group were exposed to AG (2 Gz at foot level) for 30 min twice daily, during which time cycling exercise of 80-95 % anaerobic threshold (AT) intensity was undertaken. Orthostatic tolerance (OT), exercise tests, and blood assays were determined before and after 4 days head-down bed rest (HDBR). Cardiac systolic function was measured every day. After HDBR, OT decreased to 50.9 % and 77.5 % of pre-HDBR values in control and CM groups, respectively. Exercise endurance, maximal oxygen consumption, and AT decreased to 96.5 %, 91.5 % and 91.8 % of pre-HDBR values, respectively, in the control group. Nevertheless, there were slight changes in the CM group. HDBR increased heart rate, sympathetic activity, and the pre-ejection period, but decreased plasma volume, parasympathetic activity and left-ventricular ejection time in the control group, whereas these effects were eliminated in the CM group. Aldosterone had no change in the control group but increased significantly in the CM group. Our study shows that 80-95 % AT aerobic exercise based on 2 Gz of AG preserves OT and exercise endurance, and affects body fluid regulation during short-term HDBR. The underlying mechanisms might involve maintained cardiac systolic function, preserved plasma volume, and improved sympathetic responses to orthostatic stress.

Prognostic significance of myocardial energy expenditure and myocardial efficiency in patients with heart failure with reduced ejection fraction

In heart failure with reduced ejection fraction (HFrEF) patients, myocardial blood flow (MBF), myocardial energy expenditure (MEE), myocardial efficiency has been poorly evaluated because of the necessity of invasive procedures in the determination of these parameters. Transthoracic echocardiography (TTE) can provide reliable data for MEE, MBF (via coronary sinus (CS) flows). Also, myocardial efficiency can be evaluated by the MEE to MBF ratio. We aim to assess MBF, MEE and energy efficiency and the prognostic value of these parameters in HFrEF. In this prospective study, a total of 80 patients with HFrEF due to either ischemic or non-ischemic etiology and 20 healthy control subjects were included. Median follow-up duration was 901 (27-1004) days. MBF was calculated via coronary sinus blood flow. MEE was measured from circumferential end-systolic stress, stroke volume and left ventricular ejection time. MEE to MBF ratio was determined as MEf. Primary composite end-point (CEP) was cardiovascular mortality, heart transplantation or mechanical circulatory support. MEE and MEf were lower and MBF per minute was higher in HF group compared to control subjects whereas MBF per 100g left ventricular mass was not different. MEE and MEf have significantly negative correlation with troponin I, BNP, uric acid and positive correlation with epicardial fat thickness. In Cox regression analysis, per one calorie decrease of MEE was associated 4.3 times increased risk [HR 4.396 (95% CI 1.230-15.716)] and per one percent decrease of MEf was associated 3.3 times increased risk of CEP [HR 3.343 (95% CI 1.025-10.905)]. Our study demonstrated that while MEE and MEf diminished in HFrEF, MBF preserved with the symptomatic progression of HF. MEE and MEf were found to be associated with important prognostic markers and independent predictors of CEP in HFrEF. Evaluation of MEE, MBF and MEf with echocardiography may provide an additional data regarding prognostic assessment of HFrEF population.

126 - Systolic Time Ratios via Hemotag and 2D Echocardiography: Correlations with Ejection Fraction and Implications for Clinical Practice

Background: Cardiac time intervals (CTI) have been classically obtained with phonocardiography, though this technique has been overlooked since the advent of the 2D M-mode echocardiography. The “HemoTag” is a new technology that uses heart sounds and an ECG signal transduced via 3 thoracic electrodes to measure CTI and can potentially constitute a quick and cost effective means of assessing patient's left ventricular (LV) function. “HemoTag” indices were assessed as a predictor of bi-plane Simpson's ejection fraction as established echocardiographic measures of systolic dysfunction, using a variety of prediction models. Methods: 103 consecutive patients were recruited at an outpatient cardiology clinic from March to September 2016. CTI measurements were obtained for all patients using both conventional echocardiography and via “HemoTag”. Of interest were the Pre-Ejection Period (PEP) and LV ejection time (LVET), which were evaluated for correlation with LVET using the systolic time ratio (STR), STR = PEP/LVET. Results: The female to male ratio was 0.91 and the mean age was 70 ± 15 years. The mean systolic blood pressure was 129 ± 21 mmHg. Using a threshold-based model, a sensitivity of 100%, specificity of 83.33% and accuracy of 86.9% was noted. With a linear regression-based prediction model, a sensitivity of 86.7%, specificity of 80% and accuracy of 86.3% was noted. With a support vector machine (SVM)-based prediction model, a sensitivity of 97%, specificity of 92% and accuracy of 96.3% was noted. Patients were then randomly allocated into two subsets, one to drive the model and the other to validate it. Using a logistic regression, an ROC curve was employed to assess performance with an AUC of 0.75 in the validation set. Conclusion: “HemoTag” represents a cost effective and potentially widely applicable technology that can be used for the assessment of LV function. Larger studies are needed to reinforce the conclusions stated above.

Effects of cardiac timing and peripheral resistance on measurement of pulse wave velocity for assessment of arterial stiffness

To investigate the effects of heart rate (HR), left ventricular ejection time (LVET) and wave reflection on arterial stiffness as assessed by pulse wave velocity (PWV), a pulse wave propagation simulation system (PWPSim) based on the transmission line model of the arterial tree was developed and was applied to investigate pulse wave propagation. HR, LVET, arterial elastic modulus and peripheral resistance were increased from 60 to 100 beats per minute (bpm), 0.1 to 0.45 seconds, 0.5 to 1.5 times and 0.5 to 1.5 times of the normal value, respectively. Carotid-femoral PWV (cfPWV) and brachial-ankle PWV (baPWV) were calculated by intersecting tangent method (cfPWVtan and baPWVtan), maximum slope (cfPWVmax and baPWVmax), and using the Moens-Korteweg equation ({bf{cfPW}}{{bf{V}}}_{{{bf{c}}}_{{bf{0}}}} and {bf{baPW}}{{bf{V}}}_{{{bf{c}}}_{{bf{0}}}}). Results showed cfPWV and baPWV increased significantly with arterial elastic modulus but did not increase with HR when using a constant elastic modulus. However there were significant LVET dependencies of cfPWVtan and baPWVtan (0.17 ± 0.13 and 0.17 ± 0.08 m/s per 50 ms), and low peripheral resistance dependencies of cfPWVtan, cfPWVmax, baPWVtan and baPWVmax (0.04 ± 0.01, 0.06 ± 0.04, 0.06 ± 0.03 and 0.09 ± 0.07 m/s per 10% peripheral resistance), respectively. This study demonstrated that LVET dominates the effect on calculated PWV compared to HR and peripheral resistance when arterial elastic modulus is constant.

Evaluation of the applicability and usefulness of Myocardial Performance Index in predicting the development of heart failure in comparison with other cardiac indices

Back ground: The myocardial performance (MPI) is a combined index of systolic and diastolic dysfunction and has been shown to be a predictor of cardiovascular outcome in heart diseases.&#x0D; Aim : Evaluate the role of MPI in assessment of heart failure in comparison with other echocardiographic parameters. Methods : By M-mode echocardiography, measurement of ejection fraction (EF) and stroke volume (SV) had been done, then measurement of left ventricular mass (LVM ) by measurement of left ventricular internal dimension in diastole (LVIDd) and systole (LVIDs), posterior wall thickness in diastole (PWTd), and interventricular septal thickness in diastole (IVSd). Left ventricular mass (LVM) was calculated from the measurements of the left ventricle (LV) using the equation: LVM (g) = 0.81 [1.04 (interventricular septal thickness + posterior wall thickness + LV end-diastolic internal dimension)3 – (LV end-diastolic internal dimension)3] + 0.6. Left ventricular mass index calculated by dividing LVM on body surface area. Measurement of MPI by the apical five-chamber view with Doppler study . the sum of the isovolumic relaxation time (IVRT) and isovolumic contraction time (IVCT) divided by the left ventricular ejection time (LVET) obtained from the left ventricular inflow and outflow. Results: The percentage of abnormal MPI in this study is about 82% (normal value is 0.39±0.05) in comparison to EF and SV which are 39% and 54.2% respectively. MPI showed weak but negative correlation with EF and SV ( r = -0.163, -0.044) respectively, and positive correlation with LVM and LVMI (r = 0.416 , 0.413) respectively. EF showed negative correlation with LVET, IVCT and IVRT( r = -0.03 , -0.028 , -0.25 ) respectively . Conclusion : Use of MPI for assessing cardiac performance has a potential clinical advantage over the use of other classical echocardiographic indices

Defects in Vascular Mechanics Due to Aging in Rats: Studies on Arterial Wave Properties from a Single Aortic Pressure Pulse.

Changes in vascular mechanics due to aging include elevated vascular impedance, diminished aorta distensibility, and an accelerated return of pulse wave reflection, which may increase the systolic workload on the heart. Classically, the accurate measurement of vascular mechanics requires the simultaneous recording of aortic pressure and flow signals. In practice, it is feasible to estimate arterial wave properties in terms of wave transit time (τw) and wave reflection index (RI) by using aortic pressure signal alone. In this study, we determined the τw and magnitudes of the forward (∣Pf∣) and backward (∣Pb∣) pressure waves in Long–Evans male rats aged 4 (n = 14), 6 (n = 17), 12 (n = 17), and 18 (n = 24) months, based on the measured aortic pressure and an assumed triangular flow (Qtri). The pulsatile pressure wave was the only signal recorded in the ascending aorta by using a high-fidelity pressure sensor. The base of the unknown Qtri was constructed using a duration, which equals to the ejection time. The timing at the peak of the triangle was derived using the fourth-order derivative of the aortic pressure waveform. In the 18-month-old rats, the ratio of τw to left ventricular ejection time (LVET) decreased, indicating a decline in the distensibility of the aorta. The increased ∣Pb∣ associated with unaltered ∣Pf∣ enhanced the RI in the older rats. The augmentation index (AI) also increased significantly with age. A significant negative correlation between the AI and τw/LVET was observed: AI = −0.7424 − 0.9026 × (τw/LVET) (r = 0.4901; P < 0.0001). By contrast, RI was positively linearly correlated with the AI as follows: AI = −0.4844 + 2.3634 × RI (r = 0.8423; P < 0.0001). Both the decreased τw/LVET and increased RI suggested that the aging process may increase the AI, thereby increasing the systolic hydraulic load on the heart. The novelty of the study is that Qtri is constructed using the measured aortic pressure wave to approximate its corresponding flow signal, and that calibration of Qtri is not essential in the analysis.

Efficacy of left ventricular ejection time in guiding volume management during liver transplantation

Objective To evaluate the efficacy of left ventricular ejection time(LVET)in guiding the volume management during liver transplantation. Methods Sixty American Society of Anesthesiologists physical status Ⅱ or Ⅲ patients, aged 32-64 yr, weighing 54-93 kg, of Child-Pugh grade A or B liver function, scheduled for elective the first liver transplantation with general anesthesia, were divided into either control group(group C)or transesophageal echocardiography(TEE)monitoring group(group TEE), with 30 patients in each group.In group C, the fluctuating range of mean arterial pressure, heart rate and central venous pressure was maintained less than 20% of the baseline value, and the urine volume was maintained >1 ml·kg-1·h-1.LVET was maintained between 0.35-0.40 s in group TEE.The consumption of intraoperative vasoactive agents(dopamine, norepinephrine, epinephrine), volume of fluid infused, volume of blood transfused, blood loss and urine volume were recorded.The occurrence of adverse events was observed during the perioperative period, and postoperative extubation time and intensive care unit residence time were also recorded. Results Compared with group C, the consumption of intraoperative dopamine and norepinephrine was significantly decreased, the urine volume was increased, the incidence of myocardial ischemia, pulmonary edema and renal failure in the perioperative period was decreased, and the postoperative extubation time and intensive care unit residence time were shortened in group TEE(P 0.05). Conclusion LVET produces good efficacy in guiding the volume management during liver transplantation. Key words: Stroke volume; Liver transplantation; Volume management

Higher exercise intensity delays postexercise recovery of impedance-derived cardiac sympathetic activity.

Systolic time intervals (STIs) provide noninvasive insights into cardiac sympathetic neural activity (cSNA). As the effect of exercise intensity on postexercise STI recovery is unclear, this study investigated the STI recovery profile after different exercise intensities. Eleven healthy males cycled for 8 min at 3 separate intensities: LOW (40%-45%), MOD (75%-80%), and HIGH (90%-95%) of heart-rate (HR) reserve. Bio-impedance cardiography was used to assess STIs - primarily pre-ejection period (PEP; inversely correlated with cSNA), as well as left ventricular ejection time (LVET) and PEP:LVET - during 10 min seated recovery immediately postexercise. Heart-rate variability (HRV), i.e., natural-logarithm of root mean square of successive differences (Ln-RMSSD), was calculated as an index of cardiac parasympathetic neural activity (cPNA). Higher preceding exercise intensity elicited a slower recovery of HR and Ln-RMSSD (p < 0.001), and these measures did not return to baseline by 10 min following any intensity (p ≤ 0.009). Recovery of STIs was also slower following higher intensity exercise (p ≤ 0.002). By 30 s postexercise, higher preceding intensity resulted in a lower PEP (98 ± 14 ms, 75 ± 6 ms, 66 ± 5 ms for LOW, MOD, and HIGH, respectively, p < 0.001). PEP recovered to baseline (143 ± 11 ms) by 5 min following LOW (139 ± 13 ms, p = 0.590) and by 10 min following MOD (145 ± 17 ms, p = 0.602), but was still suppressed at 10 min following HIGH (123 ± 21 ms, p = 0.012). Higher preceding exercise intensity attenuated the recovery of indices for cSNA (from STIs) and cPNA (from HRV) in a graded dose-response fashion. While exercise intensity must be considered, acute recovery may be a valuable period during which to concurrently monitor these noninvasive indices, to identify potentially abnormal cardiac autonomic responses.

Subendocardial viability ratio in patients with rheumatoid arthritis: comparison with healthy controls and identification of prognostic factors.

Cardiac involvement is common in rheumatoid arthritis. Subendocardial viability ratio (SEVR) is a non-invasive measure of microvascular coronary perfusion, yet it remains unclear whether it is affected in rheumatoid arthritis patients. We additionally sought predictors of SEVR in rheumatoid arthritis among a wide range of disease-related parameters, cardiac and hemodynamic factors, and markers of atherosclerosis, arteriosclerosis, and endothelial dysfunction. SEVR was estimated in rheumatoid arthritis patients and healthy controls by applanation tonometry, which was also used to evaluate arterial stiffness (pulse wave velocity and augmentation index). In the rheumatoid arthritis group, carotid intima-media thickness (cIMT) was additionally estimated by ultrasound, cardiac and hemodynamic parameters by impedance cardiography, and endothelial dysfunction by measurement of asymmetric dimethylarginine (ADMA). In a total of 122 participants, SEVR was lower among 91 patients with rheumatoid arthritis compared to 31 controls (141.4±21.9 vs 153.1±18.7%, p=0.009) and remained so among 29 rheumatoid arthritis patients without hypertension, diabetes, or cardiovascular diseases, compared to the control group (139.7±21.7 vs 153.1±18.7%, p=0.013). SEVR did not significantly correlate with arterial stiffness, cIMT, ADMA, or disease-related parameters. Multivariate analysis revealed gender (p=0.007), blood pressure (p=0.028), heart rate (p=0.025), cholesterol levels (p=0.008), cardiac index (p<0.001) and left ventricular ejection time (p=0.004) as independent predictors of SEVR among patients with rheumatoid arthritis. Patients with rheumatoid arthritis exhibit lower values of SEVR compared to healthy individuals. Cardiac and hemodynamic parameters, rather than functional indices of endothelial and macrovascular dysfunction, may be useful as predictors of myocardial perfusion in rheumatoid arthritis.

Ejection time: influence of hemodynamics and site of measurement in the arterial tree.

The left ventricular ejection time is routinely measured from a peripheral arterial waveform. However, the arterial waveform undergoes constant transformation as the pulse wave propagates along the arterial tree. Our goal was to determine if the left ventricular ejection time measured peripherally in the arterial tree accurately reflected the ejection time measured through the aortic valve. Moreover, we examined/accessed the modulating influence of hemodynamics on ejection time measurements. Continuous wave Doppler waveform images through the aortic valve and the simultaneously obtained radial artery pressure waveforms were analyzed to determine central and peripheral ejection times, respectively. The peripheral ejection time was significantly longer than the simultaneously measured central ejection time (174.5±25.2 ms vs. 120.7±14.4 ms; P<0.0001; 17.4±8.7% increase). Moreover, the ejection time prolongation was accentuated at lower blood pressures, lower heart rate and lower pulse wave velocity. The time difference between centrally and peripherally measured ejection times likely reflects intrinsic vascular characteristics. Moreover, given that the ejection time also depends on blood pressure, heart rate and pulse wave velocity, peripherally measured ejection times might need to be adjusted to account for changes in these variables.

Altered Blood Flow Response to Small Muscle Mass Exercise in Cancer Survivors Treated With Adjuvant Therapy.

BackgroundAdjuvant cancer treatments have been shown to decrease cardiac function. In addition to changes in cardiovascular risk, there are several additional functional consequences including decreases in exercise capacity and increased incidence of cancer‐related fatigue. However, the effects of adjuvant cancer treatment on peripheral vascular function during exercise in cancer survivors have not been well documented. We investigated the vascular responses to exercise in cancer survivors previously treated with adjuvant cancer therapies.Methods and ResultsPeripheral vascular responses were investigated in 11 cancer survivors previously treated with adjuvant cancer therapies (age 58±6 years, 34±30 months from diagnosis) and 9 healthy controls group matched for age, sex, and maximal voluntary contraction. A dynamic handgrip exercise test at 20% maximal voluntary contraction was performed with simultaneous measurements of forearm blood flow and mean arterial pressure. Forearm vascular conductance was calculated from forearm blood flow and mean arterial pressure. Left ventricular ejection time index (LVETi) was derived from the arterial pressure wave form. Forearm blood flow was attenuated in cancer therapies compared to control at 20% maximal voluntary contraction (189.8±53.8 vs 247.9±80.3 mL·min−1, respectively). Forearm vascular conductance was not different between groups at rest or during exercise. Mean arterial pressure response to exercise was attenuated in cancer therapies compared to controls (107.8±10.8 vs 119.2±16.2 mm Hg). LEVTi was lower in cancer therapies compared to controls.ConclusionsThese data suggest an attenuated exercise blood flow response in cancer survivors ≈34 months following adjuvant cancer therapy that may be attributed to an attenuated increase in mean arterial pressure.