Total Stroke Volume Research Articles

Atrial aspiration from pulmonary and caval veins is caused by ventricular contraction and secures 70% of the total stroke volume independent of resting heart rate and heart size

Whereas ventricular filling has been extensively studied and debated, atrial filling is less well characterized. Therefore, the aim of this study was to quantify atrial filling secured during ventricular diastole and systole, and to investigate whether atrial filling depends on heart rate (HR) and total heart volume (THV). Thirty-two athletes (16 women) and 32 normal subjects (16 women) underwent cardiac magnetic resonance imaging. Cardiac volumes and atrioventricular plane displacement (AVPD) were determined. Longitudinal and radial contribution to stroke volume was calculated using planimetry and used to determine diastolic and systolic atrial filling. Atrial filling during ventricular diastole was 29±10% of the total stroke volume, and during ventricular systole atrial filling was 68±8% of the total stroke volume. There were no differences between groups of different HR (P=0·70 and P=0·41 for diastolic and systolic filling, respectively) or THV (P=0·44 and P=0·46 for diastolic and systolic filling, respectively). Systolic atrial filling was strongly correlated to longitudinal ventricular pumping (R=0·76, P<0·001). This study demonstrated that in healthy humans at rest, approximately 30% of the total stroke volume enters the atria during ventricular diastole and approximately 70% during systole, independent of heart rate (HR) or heart size. The atria are filled through suction driven by ventricular longitudinal contraction which aspirates blood from the pulmonary and caval veins. As 70% of the atrial filling occurs during ventricular emptying, the heart volume remains relatively constant over the cardiac cycle, which minimizes pulling on surrounding tissues and therefore optimizes energy expenditure.

Exploring the Link Between Cardiovascular Reactivity and End-Organ Damage in African and Caucasian Men: The SABPA Study

Heart failure in the African population is reaching alarming levels. Increased afterload as a result of increased vasoconstriction during stress may lead to impaired ventricular function and stroke volume (SV) as well as vascular hypertrophy. In this study, we challenged the cardiovascular system in order to evaluate the possible contribution of indicators of α-adrenergic vasoconstriction (i.e., vascular resistance and SV reactivity) on left ventricular mass and carotid intima-media thickness (CIMT) in African and Caucasian men. We evaluated 101 African and 101 Caucasian male schoolteachers. Ambulatory blood pressure measurements were taken. Total peripheral resistance, Windkessel compliance and SV, and resting and reactivity values were obtained using a Finometer device while the Stroop color word conflict test was being applied. The electrocardiogram was recorded to obtain the Cornell product as indication of left ventricular mass. The CIMT was measured and the cross-sectional wall area (CSWA) calculated. African men showed higher total vascular resistance resting values as well as higher positive reactivity values compared with Caucasian men. The SV decreased significantly during stress in African men while resting blood pressure and the Cornell product value increased. SV showed a consistent association with left ventricular mass (β = -0.21; P = 0.04) and CSWA (β = -0.24; P = 0.01) in single and multiple regression analyses. No such associations were evident in the Caucasian men. African men showed a suppressed SV, possibly as a result of an increased ventricular afterload leading to end-organ damage.

Prospective Comparison of Valve Regurgitation Quantitation by Cardiac Magnetic Resonance Imaging and Transthoracic Echocardiography

Both transthoracic echocardiography (TTE) and cardiac magnetic resonance (CMR) imaging allow quantification of chronic aortic regurgitation (AR) and mitral regurgitation (MR). We hypothesized that CMR measurement of regurgitant volume (RVol) is more reproducible than TTE. TTE and CMR performed on the same day in 57 prospectively enrolled adults (31 with AR, 26 with MR) were measured by 2 independent physicians. TTE RVol(AR) was calculated as Doppler left ventricular outflow minus inflow stroke volume. RVol(MR) was calculated by both the proximal isovelocity surface area method and Doppler volume flow at 2 sites. CMR RVol(AR) was calculated by phase-contrast velocity mapping at the aortic sinuses and RVol(MR) as total left ventricular minus forward stroke volume. Intraobserver and interobserver variabilities were similar. For AR, the Bland-Altman mean interobserver difference in RVol was -0.7 mL (95% confidence interval [CI], -5 to 4) for CMR and -9 mL (95% CI, -53 to -36) for TTE. The Pearson correlation was higher (P=0.001) between CMR (0.99) than TTE readers (0.89). For MR, the Bland-Altman mean difference in RVol between observers was -4 mL (95% CI, -21 to 13) for CMR compared with 0.7 mL (95% CI, -30 to 32) for the proximal isovelocity surface area and -10 mL (95% CI, -76 to 56) for TTE volume flow at 2 sites. Correlation was similar for CMR (0.94) versus TTE readers (0.90 for the proximal isovelocity surface area). Compared with TTE, CMR has lower intraobserver and interobserver variabilities for RVol(AR), suggesting CMR may be superior for serial measurements. Although RVol(MR) is similar by TTE and CMR, variability in measured RVol by both approaches suggests that caution is needed in clinical practice.

Early Left Atrial Mechanics and Volume Abnormalities in Subjects with Prehypertension: A Real Time Three-Dimensional Echocardiography Study

The aim of this study was to evaluate left atrial (LA) volume and mechanical functions by real time three-dimensional echocardiography (RT3DE) in prehypertensive subjects. The study included 54 (34 male and 20 female) prehypertensive subjects and 36 (14 male and 22 female) healthy control subjects. Transthoracic echocardiography and RT3DE were performed in all patients. Interventricular septum thickness and isovolumetric relaxation time were significantly higher in prehypertensives than in controls (10.7 ± 0.7 vs. 10.1 ± 0.8 P = 0.001 and 89.9 ± 10 vs. 82.4 ± 11 P = 0.002, respectively). LA maximum volume, volume before atrial contraction, total and active stroke volume, total and active emptying fractions, expansion index, and LA max volume index were significantly higher in prehypertensives when compared with controls (P < 0.0001 for all). However, the passive emptying fraction was significantly lower in prehypertensives than controls (45.7 ± 5.6 vs. 48.6 ± 4.1, P = 0.006), and the minimum LA volume between the two groups was similar. The main finding of this study was that although LA volume and LA active systolic functions were significantly increased in prehypertensive people, there was a reduction in passive LA systolic functions. These parameters may be important in showing hemodynamic and structural changes in cardiac tissue caused by prehypertension.

Equal stroke volumes, different costs: left ventricular 4D flow in normal and failing hearts

Summary Although total left ventricular (LV) stroke volume (SV) is equal in healthy subjects and heart failure patients with mild LV remodeling, the SV’s transventricular flow paths to ejection and diastolic energetics are different. These flow-specific markers of inefficiency of the failing heart are detectable prior to clinical decompensation, and might be predictors of progressive adverse cardiac remodeling. Background Heart failure is a common disorder with a dismal prognosis. Cardiac remodeling is a key component of heart failure that progresses from adaptive to maladaptive as the disease worsens, and is associated with increased risks of symptoms and mortality. In earlier stages of heart failure with adaptive remodeling, patients may remain clinically compensated and the failing heart’ sl eft ventricular (LV) stroke volume (SV) remains the same as in the normal heart. Recently, time-varying and complex three-dimensional flow patterns and energetics within the normal LV have been demonstrated. Based on such 4D flow-specific measures, we hypothesized that while the SV of normal and failing LVs may be equal, the SV’s diastolic kinetic energy (KE) and transventricular routes to ejection are different in the two states. Methods In ten patients with dilated cardiomyopathy (DCM) (6 females, 49±14 years [mean±SD]) and ten healthy subjects (4 female, 44±17 years), 4D phase-contrast CMR velocity data and morphological data were acquired at 1.5T (Philips Achieva). A previously validated method was used for the analysis: The LV endocardium was segmented from the morphological images at end-diastole (ED) and end-systole. Pathlines were emitted from the ED blood volume and traced forward and backward in time until end-systole, allowing separation of the Total SV into two flow components (figure 1): 1) Blood that enters and leaves the LV during the analyzed cardiac cycle (Direct SV), and 2) Blood that leaves but does not enter the LV during the analyzed cardiac cycle (Delayed SV). The KE was calculated over the cardiac cycle for these flow components based on the volume occupied by each pathline, its velocity, and blood density. Results The LV ED volume was larger and LV ejection fraction was smaller in DCM compared to healthy (179±33 vs 147±22 ml, p=0.021, and 42±5 vs 54±6 %, p<0.001, respectively). While the Total SV was equal in the two groups (77±19 vs 79±16 ml, p=0.8), the Direct SV represented a significantly smaller part of the Total SV in DCM compared to healthy (45±11 vs 69±5 %, p<0.001) (figure 2). At ED, the “KE of the Direct SV” / “KE of the Total SV”-ratio was lower in DCM compared to healthy (47±15 vs 76±7 %, p<0.001) (figure 2). Conclusions Although total LV stroke volume is equal in healthy subjects and in clinically compensated heart failure patients with mild LV remodeling, the diastolic routes through the LV and pre-systolic energetics of the SV are significantly different in the two states. Inefficient flow may augment the chronic stress on the failing heart’s reserve, promoting progressive maladaptive cardiac remodeling.

Left atrial volume and function in patients with Behcet's disease assessed by real-time three-dimensional echocardiography

Behçet's disease (BD), a multisystemic inflammatory disorder, has been associated with a number of cardiovascular dysfunctions, including endomyocardial fibrosis of the right heart, atrial fibrillation, ventricular arrhythmias and sudden cardiac death. The incidence and nature of cardiac involvement in BD are not yet clearly documented. Our aim was to evaluate left atrial (LA) volume and functions using real-time three-dimensional echocardiography (RT3DE) in Behcet's patients without any cardiac symptom. The study included 40 BD (16 females, 24 males and mean age of 33±7 years) and 30 healthy (11 females, 19 males and mean age of 35±6 years) subjects. All the patients' demographic parameters such as age, gender, and duration of BD were recorded. All the individuals underwent comprehensive 2D echocardiography examination, and RT3DE was performed to assess LA volumes and mechanical functions. LA maximum volume (Vmax) and before atrial contraction volume (Vpre A), LA active stroke volume and total stroke volumes (TSV), total emptying and active emptying fractions and expansion index were significantly higher in Behcet's disease patients when compared with the controls (P<0.0001 for all). LA passive emptying fraction was significantly lower in the patients with BD than in the controls (41±7 vs. 44±5, P=0.039). There were positive correlations between TSV and high-sensitive C-reactive protein level (r=0.413, P=0.008), TSV, and disease duration (r=0.417, P<0.007). Our study has shown that LA mechanical functions and volumes are impaired in BD. These results may be an early form of subclinical cardiac involvement in patients with BD who have no clinical evidence for cardiovascular disease.

Left ventricular fluid dynamics in heart failure: echocardiographic measurement and utilities of vortex formation time

In clinical heart failure (HF), inefficient propagation of blood through the left ventricle (LV) may result from suboptimal vortex formation (VF) ability of the LV during early diastole. We aim to (i) validate echocardiographic-derived vortex formation time (adapted) (VFTa) in control subjects and (ii) examine its utility in both systolic and diastolic HF. Transthoracic echocardiography was performed in 32 normal subjects and in 130 patients who were hospitalized with HF [91, reduced ejection fraction (rEF) and 39, preserved ejection fraction (pEF)]. In addition to biplane left ventricular ejection fraction (LVEF) and conventional parameters, the Tei index and tissue Doppler (TD) indices were measured. VFTa was obtained using the formula: 4 × (1 - β)/π × α³ × LVEF, where β is the fraction of total transmitral diastolic stroke volume contributed by atrial contraction (assessed by time velocity integral of the mitral E- and A-waves) and α is the biplane end-diastolic volume (EDV)(1/3) divided by mitral annular diameter during early diastole. VFTa was correlated with demographic, cardiac parameters, and a composite clinical endpoint comprising cardiac death and repeat hospitalization for HF. Mean VFTa was 2.67 ± 0.8 in control subjects; reduced in HF, preserved EF HF, 2.21 ± 0.8; HF with reduced EF, 1.25 ± 0.6 (P< 0.001). It was not affected by age, gender, body surface area but was correlated positively with TD early diastolic myocardial velocities (E', septal, r = 0.46; lateral, r = 0.43), systolic myocardial velocities (S', septal, r = 0.47; lateral, r = 0.41), and inversely with the Tei index (r = -0.41); all Ps < 0.001. Sixty-two HF patients (49%) met the composite endpoint. VFTa of <1.32 was associated with significantly reduced event-free survival (Kaplan Meier log rank = 16.3, P= 0.0001) and predicted the endpoint with a sensitivity and specificity of 65 and 72%, respectively. VFTa, a dimensionless index, incorporating LV geometry, systolic and diastolic parameters, may be useful in the diagnosis and prognosis of HF.

Automated Quantification of Mitral Inflow and Aortic Outflow Stroke Volumes by Three-Dimensional Real-Time Volume Color-Flow Doppler Transthoracic Echocardiography: Comparison with Pulsed-Wave Doppler and Cardiac Magnetic Resonance Imaging

The aim of this study was to compare the feasibility, accuracy, and reproducibility of automated quantification of mitral inflow and aortic stroke volumes (SVs) using real-time three-dimensional volume color-flow Doppler transthoracic echocardiography (RT-VCFD), with cardiac magnetic resonance (CMR) imaging as the reference method. In 44 patients (86% of the screened patients) without valvular disease, RT-VCFD, CMR left ventricular short-axis cines and aortic phase-contrast flow measurement and two-dimensional (2D) transthoracic echocardiography (TTE) were performed. Dedicated software was used to automatically measure mitral inflow and aortic SVs with RT-VCFD. CMR total SV was calculated using planimetry of short-axis slices and aortic SV by phase-contrast imaging. SVs by 2D TTE were computed in the conventional manner. The mean age of the included patients was 40 ± 16 years, and the mean left ventricular ejection fraction was 61 ± 9%. Automated flow measurements were feasible in all study patients. Mitral inflow SV by 2D TTE and RT-VCFD were 85.0 ± 21.5 and 94.5 ± 22.0 mL, respectively, while total SV by CMR was 95.6 ± 22.7 mL (P < .001, analysis of variance). On post hoc analysis, mitral inflow SV by RT-VCFD was not different from the CMR value (P = .99), while SV on 2D TTE was underestimated (P = .001). The respective aortic SVs were 82.8 ± 22.3, 94.2 ± 22.3, and 93.4 ± 24.6 mL (P < .001). On post hoc analysis, aortic SV by RT-VCFD was not different from the CMR value (P = .99), while SV on 2D TTE was underestimated (P = .006). The interobserver variability for SV measurements was significantly worse for 2D TTE compared with RT-VCFD. RT-VCFD imaging with an automated quantification algorithm is feasible, accurate, and reproducible for the measurement of mitral inflow and aortic SVs and is superior to manual 2D TTE-based measurements. The rapid and automated measurements make this technique practical in the clinical setting to measure and report SVs routinely where the acoustic window will allow it, which was 86% in our study.

Three-Dimensional Echocardiography in Paravalvular Aortic Regurgitation Assessment after Transcatheter Aortic Valve Implantation

Paravalvular aortic regurgitation (AR) after transcatheter aortic valve implantation (TAVI) is common, but the evaluation of its severity by two-dimensional (2D) transthoracic echocardiography (TTE) presents several constrains. The aim of this study was to assess the usefulness of a new methodology, using three-dimensional (3D) TTE, for better assessment of paravalvular AR after TAVI. Two-dimensional and 3D TTE was performed in 72 patients, 5 months after TAVI, using the X5-1 PureWave microbeamforming xMATRIX probe. The position and severity of the paravalvular AR jets were described using 2D and 3D TTE, and a model was designed for paravalvular AR systematic location description. Vena contracta width was measured using 2D transthoracic echocardiographic views, and the planimetry of the vena contracta was assessed after the perfect alignment plane was obtained using the multiplanar 3D transthoracic echocardiographic reconstruction tool. AR volume was calculated as the difference between 3D TTE-derived total left ventricular stroke volume and right ventricular stroke volume estimated using 2D TTE. Diagnostic efficiency for moderate AR was assessed using receiver operating characteristic curve analysis. Forty-three patients (57.4%) presented with AR; 10 (13.3%) had central AR, and 33 (44.0%) had paravalvular AR jets. Vena contracta widths were similar between patients with moderate and mild AR (2.1 ± 0.53 vs 1.9 ± 0.16 mm, P = .16), but vena contracta planimetry was larger in patients with moderate AR than in those with mild AR (0.30 ± 0.12 vs 0.09 ± 0.07 cm(2), P = .001). Vena contracta planimetry on 3D TTE was better correlated with AR volume than vena contracta width on 2D TTE (Kendall's τ = 0.82 [P < .001] vs 0.66 [P < .001]). The areas under the receiver operating characteristic curves were 0.96 for vena contracta planimetry and 0.35 for vena contracta width. This study proposes an alternative methodology for paravalvular AR assessment after TAVI. Using vena contracta planimetry on 3D TTE, an accurate methodology for paravalvular AR jet evaluation and moderate AR classification is described.

Relationship between breathing and cardiovascular function at rest: sex‐related differences

to compare relationships at rest between breathing rate, levels of muscle sympathetic nerve activity, total peripheral resistance and cardiac output among young men and women. recordings were made of respiratory movements, sympathetic nerve activity (peroneal microneurography), intra-arterial blood pressure, electrocardiogram, cardiac output (open-circuit acetylene uptake technique) in 19 healthy men (age 27 (+/-) 2years, mean (+/-) SEM) and 17 healthy women (age 25 (+/-) 1years). Total peripheral resistance and stroke volume were calculated. Four minutes epochs of data were analysed. breathing rates and sympathetic activity were similar in men and women but compared to men, women had significantly lower blood pressures, cardiac output and stroke volume. In men breathing rate correlated positively with sympathetic activity (r = 0.58, P < 0.05) but not in women (r = 0.12, P > 0.05). Furthermore, in men, respiratory rate correlated positively with total peripheral resistance (r = 0.65, P < 0.05) and inversely with cardiac output (r =-0.84, P < 0.05) and heart rate (r = -0.60, P < 0.05) but there were no such relationships in women (P > 0.05 for all). the positive relationship between breathing and sympathetic activity in men, and the inverse coupling of breathing to cardiac output and heart rate suggest that influences of respiration may be important not only for dynamic but also for 'tonic' cardiovascular function. The lack of relationships among these variables in women shows that there are fundamental differences in basic blood pressure regulation between the sexes.

Color Doppler Jet Area Overestimates Regurgitant Volume when Multiple Jets are Present

Color Doppler jet area (CDJA) is an important measure used to classify mitral regurgitation (MR) severity. The investigators hypothesized that the presence and configuration of multiple regurgitant jets can alter CDJA quantification for fixed regurgitant volumes. This has relevance to MR assessment prior to the treatment of valves with multiple regurgitant orifices or after surgical or percutaneous double-orifice mitral valve repair. An in vitro model was developed to create jets flowing through a simulated mitral orifice into an imaging chamber. The flow loop was driven with a pulsatile pump at 60 beats/min containing a water-glycerol solution approximating the viscosity of blood. At the orifice, simulated regurgitant stroke volumes of 2.5 to 25 mL were created through plates having either single openings with orifice areas from 0.125 to 0.50 cm(2) or two to four openings with total orifice area of 0.25 cm(2) and varied linear spacing. An 8-MHz transthoracic two-dimensional ultrasound probe was used to acquire jet velocities by continuous-wave Doppler as well as color Doppler for offline analysis. CDJA values were obtained with custom automated pixel-counting software. Peak jet velocities ranged from 30 to 550 cm/sec. For single jets, normalized average CDJA values increased nonlinearly as a function of average Reynolds number. Peak CDJA values were up to 62% higher for multiple jets compared with single jets with similar total orifice areas and simulated regurgitant stroke volumes. The presence or absence of multiple jets, rather than the total number of jets, appeared to have a greater effect on maximum CDJA. In addition, peak CDJA values for multiple jets increased with increased linear spacing. A fixed regurgitant volume involving multiple jets will have a larger CDJA value than the same total volume from a single jet. The source of this discrepancy appears to be increased ambient fluid entrainment from adjacent regurgitant jets. This potential overestimation of MR severity using color Doppler flow jets should be taken into consideration when assessing MR prior to treatment or when assessing residual MR after double-orifice mitral valve repair.

Early and Midterm Hemodynamics After Aortic Valve Bypass (Apicoaortic Conduit) Surgery

Aortic valve bypass (AVB [apicoaortic conduit]) relieves aortic stenosis (AS) by connecting the apex of the left ventricle to the descending thoracic aorta with a valved conduit. AVB is performed through a small left thoracotomy, without cardiopulmonary bypass, aortic cross-clamping, cardiac arrest, or debridement of the native aortic valve. Little is known about hemodynamics, including ventricular performance, relative conduit blood flow, and progression of native AS after AVB. Forty-seven very high risk patients underwent AVB for AS between 2003 and 2009. The mean age was 82 years. Predismissal and interval transthoracic quantitative two-dimensional and Doppler echocardiography was performed in a core laboratory. No patient had obstruction of the native aortic valve or the conduit during follow-up. The AVB effectively relieved left ventricular outflow tract obstruction (average peak gradient across the conduit was 5.6 +/- 3.8 mm Hg). Native aortic valve stenosis did not progress after AVB (0.63 +/- 0.16 cm(2) before surgery to 0.7 +/- 0.24 cm(2) at latest follow-up more than 6 months; p = 0.16). Total stroke volume increased after AVB from 60 mL +/- 22 mL to 107 mL +/- 27 mL (p < 0.0001). Left ventricular outflow was distributed in a predictable fashion between the conduit and the native aortic valve, with 63% +/- 10% of the flow directed to the conduit. Relative conduit flow remained stable (68% +/- 8%) at latest follow-up more than 6 months (p = 0.17). Aortic valve bypass effectively relieves the outflow tract obstruction of AS. Placement of an apical valved conduit halts the biologic progression of AS.

Age-related hemodynamic changes during vasovagal syncope

Objective The aim of our study was to identify specific age-related hemodynamic changes during upright tilt test in patients with vasovagal syncope. Methods We studied 115 subjects who were referred to us for unexplained syncope during 65° tilt with pharmacological challenge (s.l. nitrate) by noninvasive monitoring of blood pressure (Finometer). Two derived variables were also considered: total peripheral resistance and stroke volume. The patients were divided into 3 groups by age: Group 1, 10–30 yrs; Group 2, 31–50 yrs; and Group 3, > 51 yrs. Results The test was positive in 65 patients (57%). During the first 20 min of the test, older patients experienced lower increases in heart rate ( p < 0.00001) and premature reduction of total peripheral resistance ( p < 0.005) and systolic blood pressure ( p < 0.005). Group 1 showed more pronounced decreases in stroke volume ( p < 0.01). No differences emerged between negative and positive patients. In the 5 min that preceded syncope, younger subjects experienced a distinct, transient increase in heart rate immediately before symptom onset ( p < 0.005). Blood pressure was prematurely and progressively decreased in Group 3, whereas it decreased only in the 90 s prior to syncope in Groups 1 and 2 ( p < 0.01). Conclusions Our results suggest that blunted sympathetic activation occurs during passive orthostatism in older patients. On the other hand, hemodynamic changes before symptom onset seem to indicate as in younger subjects syncope results from an excessive sympathovagal reaction, whereas in older subjects it is related to an overwhelming, progressive central vagal activity that is associated with a defective peripheral sympathetic activation.

Serum calcium revisited: associations with 24-h ambulatory blood pressure and cardiovascular reactivity in Africans

Sub-Saharan Africans face an increasing burden of hypertension. Although controversial, recent experimental evidence strongly suggests that serum calcium contributes to elevated blood pressure through increased vascular resistance. We investigated the associations of 24-h blood pressure and cardiovascular reactivity with serum calcium in African men stratified by age. The study consisted of 50 younger (median age: 38 years) and 49 older (median age: 49 years) participants. We measured 24-h ambulatory blood pressure with a mean successful inflation rate of 72.6%. Total peripheral resistance and stroke volume reactivity were obtained using a Finometer device during application of the Stroop color and word conflict test. Total serum calcium was adjusted for serum albumin. Results showed that serum calcium levels were similar between the younger and older groups. However, in the younger group, 24-h systolic blood pressure, 24-h diastolic blood pressure and total peripheral resistance reactivity correlated positively, whereas stroke volume reactivity correlated negatively with serum calcium in single and multiple regression analyses (systolic blood pressure: B=34.99, P=0.017; diastolic blood pressure: B=34.93, P<0.001; total peripheral resistance reactivity: B=65.44, P=0.048; stroke volume reactivity: B=-45.40, P=0.017). No associations were evident in the older African men. In conclusion, 24-h ambulatory systolic and diastolic blood pressures are positively associated with serum calcium in African men younger than 43 years. The blood pressure-serum calcium relationship seems to be mediated through increased vascular resistance during stress.

Cardiovascular responses to dynamic exercise in postmenopausal women

Previous studies strongly indicate that the arterial baroreflex plays an important role in cardiovascular responses to dynamic exercise. However, the effect of arterial baroreflex on the hemodynamic responses to dynamic exercise is not well understood after menopause. Therefore, we investigated the cardiovascular responses during cycle exercise (30 W and 60 W) in healthy premenopausal and postmenopausal women. Thirty premenopausal and postmenopausal women were instrumented to measure heart rate (HR), cardiac output (CO) and mean arterial pressure (MAP). MAP was significantly increased with exercise intensity in postmenopausal women, while there was no difference in premenopausal women. CO, HR, total vascular conductance (TVC) and stroke volume increased with increasing workloads in both premenopausal and postmenopausal women. However, TVC was significantly lower after menopause at moderate workload compared to the premenopausal women (107.3±13.4 vs. 91.4±5.2 mm/min/Hg). The results indicate that higher MAP after menopause occurred due to combining increase in CO as well as substantial decrease in peripheral vascular conductance. We conclude that menopause altered normal cardiovascular responses to graded dynamic exercise. Additionally, after menopause significantly a higher increase in arterial blood pressure may be due to a depression in arterial baroreflex function during exercise.

Antioxidant intravenous supplementation improves cardiac output during dynamic exercise in college soccer athletes

Antioxidant supplements are used by athletes as a means to counteract the oxidative stress of exercise. However, the effect of chronic antioxidant supplements on cardiovascular responses to dynamic exercise is not well understood. Therefore, we investigated the hemodynamic responses during cycle exercise after intravenous supplements of antioxidant vitamins in college soccer athletes. Eleven healthy subjects were instrumented to measure heart rate (HR), stroke volume (SV), cardiac output (CO) and mean arterial pressure (MAP) before and after 700 ml intravenous supplementation with antioxidant compound (B‐com, vitamin C, gluthation, vitamin B12, vitamin B5, vitamin B6, L‐ carnitine, magnesium sulphate, glycchyrizin, vitamin B1, thiot acid in isotonic sodium chloride solution), 14 times for one month. Total vascular conductance (127.1±8.7 vs. 137.2±9.3 ml/min/Hg), SV (123.7±7.8 vs. 137.8±7.7 ml), and CO (11.8±0.8 vs. 13±0.9 L) were significantly increased after the antioxidant supplements, where there were no differences in MAP and HR. The results indicate that antioxidant compound‐induced increases in SV and CO can increase oxygen delivery to exercising skeletal muscles and improve exercise performance. Effects may be due to attenuation of sympathetic‐induced vasoconstriction in skeletal muscle during dynamic exercise. Supported by Kyung Nam Pharm CO.

Caudate nucleus volumes in stroke and vascular dementia

We aimed to assess the volume of the nucleus caudatus as a neuroanatomical substrate of fronto-subcortical circuits, in stroke patients with/without dementia, and the relationship to potential determinants of neural circuit integrity such as white matter hyperintensities (WMH) and stroke volume. Stroke only (Stroke) ( n = 19) and stroke with Vascular Dementia (VaD) ( n = 16) and healthy control ( n = 20) subjects, matched on demographic variables, underwent extensive neuropsychiatric assessments and manual MRI-based volumetric measurements for intracranial area (ICA), stroke volume, and bilateral caudate volume. WMH on MRI were quantified using an automated algorithm. Multivariate analysis of covariance (controlling for age and ICA), revealed that across the three groups, caudate volumes were significantly different. There was a significant difference in bilateral caudate nucleus volume between subjects by diagnosis (Stroke, VaD, control). The control group was largest in overall mean volume of the diagnostic groups, followed by the Stroke group (86% of controls), and finally, the VaD group (72%). There was a partial correlation between total caudate volume and the total volume of deep WMH including periventricular regions and brainstem, controlling for ICA; and for total stroke volume. Stroke patients with VaD have smaller caudate nuclei compared to those without dementia and healthy controls, with the stroke-only patients being intermediate in their caudate volume status . There was preliminary evidence of negative correlation of caudate volume with volume of deep WMH and total stroke volume, suggesting cerebrovascular disease contributes to caudate atrophy,which, in turn may disrupt fronto-subcortical circuits.

Hemodynamic determinants of chronic hypotension and their modification through vasopressor application

Chronic low blood pressure is typically accompanied by symptoms such as fatigue, reduced drive, dizziness, headaches and cold limbs. Reduced cognitive performance, diminished cerebral blood flow and autonomic dysregulation have been furthermore documented in this condition. The present contribution reports two studies exploring systemic hemodynamics in chronic hypotension and their modification through vasopressor application. In study I, effects of the alpha-sympathomimetic midodrine were examined in 54 hypotensive individuals using a placebo-controlled double-blind design. Hemodynamic parameters were assessed at rest and during mental stress. They were derived from continuous blood pressure recordings using Modelflow analysis. The drug led to marked increases in blood pressure, total peripheral resistance and stroke volume. However, due to strong heart rate deceleration, cardiac output remained virtually unchanged. In study II, 40 hypotensive and 40 normotensive control persons were compared with respect to hemodynamics. While groups did not differ in total peripheral resistance, hypotensives exhibited markedly diminished stroke volume and heart rate, resulting in a reduction in cardiac output of 25% at rest and of 33% during mental stress. The data provide relevant knowledge about the hemodynamic mediation of chronic hypotension. In contrast to elevated blood pressure, which is mainly determined by increased peripheral resistance, reduced cardiac output may be the cardinal hemodynamic aberration in chronic hypotension. Midodrine proved to be effective in elevating blood pressure. However, given the cardiac origin of chronic hypotension and the lack of drug effect on cardiac output, alpha-sympathomimetic treatment may be suboptimal.

Abstract 5773: Reduced Left Ventricular Vortex Formation Ability Despite Preserved Ejection Fraction in Low-Flow, Low-Gradient Severe Aortic Stenosis

Background and Aim : Low-flow, low-gradient (LFLG) severe aortic stenosis (AS) despite preserved left ventricular (LV) ejection fraction (EF) has been associated with more advanced stage of the disease, lower cardiac output (CO) and higher systemic afterload. We aim to characterize the LV performance determinants, including its vortex formation (VF) ability. Methods : Echocardiography was performed in 61 consecutive patients with severe AS (aortic valve area index (AVAI) ≤ 0.6 cm 2 /m 2 ) and preserved LVEF (≥ 50%). In addition to biplane LV measurements, AS severity indices and Tei index were measured. Hemodynamic indices (including systemic vascular resistance (SVR) and valvulo-arterial impedance (VAI)) were calculated. VF index (VFI) was obtained from 4 X (1-β)/πX α 3 X LVEF where β is the fraction of total transmitral diastolic stroke volume (SVol) contributed by atrial contraction (assessed by time velocity integral of the mitral E and A waves) and α is the end diastolic volume (EDV) 1/3 divided by mitral annular diameter during early diastole. Patients were categorized by their LV SVol index (SVI). LFLG group consisted of SVI &lt; 45ml/m 2 . Results : Mean VFI was 2.67±1.1; AVAI, 0.50±0.09 cm 2 /m 2 . Though AVAI was slightly lower in LFLG, dimensionless index and aortic valve resistance were similar and associated with no difference in LV mass and volume between the 2 groups. VFI was significantly reduced in the LFLG, 2.37±0.9 vs 3.12±1.3 ( P =0.01), However other LV functional parameters including Tei index and LVEF were similar (Table ). LFLG was associated with higher SVR and VAI (Table ). In LFLG, the only significant correlates of VFI were SVR (r=0.38), VAI (0.37) and stroke work index (0.36); all P s&lt;0.05. VFI did not correlate to these parameters in the non-LFLG group. Conclusion : In LFLG severe AS, increased afterload and suboptimal LV vortex formation ability contribute to lower CO/SV. VFI provides useful insights in understanding this relatively new entity. Comparison of echocardiographic and haemodynamic data in LFLG and non-LFLG groups

Abstract 3289: Vortex Formation Index in Heart Failure: Novel Non-invasive Assessment Of Fluid Dynamics using Transthoracic Echocardiography

Background: In clinical heart failure (HF), inefficient propagation of blood through the left ventricle (LV) may result from suboptimal vortex formation (VF) ability of the LV during early diastole. We aim to validate echocardiographic-derived VF index (VFI) in normal subjects and examine its utility in both systolic and diastolic HF. Method: Echocardiography was performed in 100 normals and 155 pts admitted with HF (110, systolic and 45, isolated diastolic failure). In additon to biplane LV ejection fraction (EF) and conventional parameters, the Tei index and tissue Doppler (TD) indices were measured. VFI was obtained using: 4 X (1-β) / πX α 3 X LVEF where β is the fraction of total transmitral diastolic stroke volume contributed by atrial contraction (assessed by time velocity integral of the mitral E and A waves) and α is the biplane end diastolic volume (EDV) 1/3 divided by mitral annular diameter during early diastole. Results: Mean VFI was 2.75 ± 0.7 in control subjects; reduced in heart failure, diastolic, 2.21 ± 0.8; systolic, 1.24 ± 0.5 (P&lt;0.001, Fig 1 ). It correlated positively with TD early diastolic myocardial velocities (E, septal, r =0.58; lateral, r =0.58), inversely with LV filling pressure (E/E’ septal, r =−0.42; lateral, r =−0.41) and the Tei index (r =−0.57, curvilinear relation, Fig 2 ); all Ps &lt;0.001. In comparison with age, sex and LVEF-matched controls, only VFI, but not all other echo indices, remained significantly different (attenuated) in diastolic HF patients (2.01 ± 0.7 vs 2.74 ± 0.8, P=0.005). Conclusion: VFI, a novel, dimensionless index, incorporating LV geometry, systolic and diastolic contributions to fluid dynamics, may be useful in heart failure.