Leg-positive Pressure Research Articles

Ability of Left Atrial Distensibility After Radiofrequency Catheter Ablation to Predict Recurrence of Atrial Fibrillation

This study sought to assess the left atrial (LA) functional recovery after radiofrequency catheter ablation (RFCA) for atrial fibrillation (AF) and to evaluate the determining factor of procedural success of RFCA, using a novel preload stress echocardiography. A total of 111 patients with AF were prospectively recruited. The echocardiographic parameters were obtained during the leg-positive pressure (LPP) maneuver, both at baseline and midterm after RFCA. As an index of LA distensibility, the LA expansion index was calculated as (LAVmax - LAVmin)×100 / LAVmin. During a median follow-up period of 14.2 months, AF recurrence was observed in 23 patients (20.7%). In LA functional parameters at baseline, only the Δ LA expansion index was significantly larger in the success group (16 ± 11% vs 4 ± 9%, p <0.05). At midterm follow-up, the Δ LA expansion index significantly increased to 32 ± 19% (p <0.05), together with structural LA reverse remodeling only in the success group. Moreover, the Δ stroke volume index during the LPP stress test significantly increased only in the success group (from 2.3 ± 1.3 ml/m2 to 3.1 ± 4.8 ml/m2, p <0.05). In a multivariate analysis, left ventricular ejection fraction (hazard ratio 0.911, p <0.05) and baseline Δ LA expansion index (hazard ratio 0.827, p <0.001) were independent predictors of AF recurrence. In conclusion, the baseline Δ LA expansion index during LPP stress is a reliable marker for predicting procedural success after RFCA. Moreover, maintenance of sinus rhythm resulted in an improvement of the preload reserve after RFCA.

Effects of Radiofrequency Catheter Ablation on Cardiac Reserve Using Preload Stress Echocardiography in Paroxysmal and Persistent Atrial Fibrillation

The effects of catheter ablation on exercise tolerance and quality of life in patients with atrial fibrillation (AF) have been reported. We assessed cardiac function in more detail using the leg positive pressure (LPP) technique and found that contractile reserve is particularly important in relation to exercise tolerance and prognosis. In this study, we used the LPP technique to examine changes in contractile reserve immediately after ablation and 6 months later. We prospectively enrolled patients who underwent catheter ablation for AF at 2 institutes. We performed LPP stress echocardiography 2 to 3 days after (FU-1) and 6 months after (FU-2) ablation to examine changes in cardiac function indexes. The primary end point was improvement in contractile reserve. Ultimately, 109 patients (mean age 67.4 ± 9.6 years; 70% men) underwent 2 sessions of LPP stress echocardiography. The median CHA2DS2-VASC score was 2 (interquartile range 13). From FU-1 to FU-2, the change in the stroke volume index after the LPP maneuver increased in patients with paroxysmal and persistent AF with low CHA2DS2-VASC scores (both p <0.05). Regardless of AF subtype, contractile reserve at FU-2 improved in patients with low CHA2DS2-VASC scores compared with that at FU-1. In contrast, patients with high CHA2DS2-VASC scores had no change. In conclusion, patients with AF with a low CHA2DS2-VASC score had improved contractile reserve after ablation, whereas patients with high scores did not show any improvement. Aggressive interventions in patients with high scores may lead to better management after catheter ablation.

"Accelerated aging" of the heart as heart failure with preserved ejection fraction-analysis using leg-positive pressure stress echocardiography.

The aging process is a significant risk factor for heart failure. The incidence of heart failure with preserved ejection fraction (HFpEF) dramatically increases with age. Although HFpEF occurs along a continuum of aging of the cardiovascular system, the pathophysiology that differentiates overt HFpEF from physiological aging is not fully understood. A total of 102 subjects were prospectively recruited: 25 patients with HFpEF and 77 healthy controls. Controls were stratified into three age-groups: young (n = 27, 20-40years), middle aged (n = 25, 40-65years), and elderly (n = 25, > 65years). All participants underwent preload stress echocardiography using a leg-positive pressure (LPP) maneuver. With an increase in age, progressive concentric left ventricular (LV) remodeling was observed in healthy controls, resulting in the hemodynamic consequences of an age-dependent increase in the E/e' ratio (ANOVA, P < 0.001). During LPP stress, the E/e' ratio significantly increased in the middle-aged and elderly groups (from 8 ± 2 to 9 ± 3, from 10 ± 2 to 12 ± 3, P < 0.05, respectively), and this was more pronounced in patients with HFpEF (from 16 ± 5 to 17 ± 7, P < 0.05). Forward stroke volume (SV) significantly increased in each healthy group during LPP stress (all P < 0.001) but failed to increase in the HFpEF group (from 43 ± 13 to 44 ± 14mL/m2, P = 0.65). In a multivariate analysis, LV mass index (odds ratio [OR] 1.051, P < 0.05), E/e' ratio (OR 1.480; P < 0.05), and change in SV (OR 0.780; P < 0.05) were independent parameters that differentiated HFpEF from physiological aging. Structural remodeling and impaired preload reserve may both be critical features that characterize the pathophysiology of HFpEF.

Impaired preload reserve is an important haemodynamic characteristics that discriminates between physiological ageing and overt heart failure with preserved ejection fraction

Abstract Funding Acknowledgements Type of funding sources: None. Background Ageing process per se is a major risk factor for heart failure (HF). In fact, the incidence of HF with preserved ejection fraction (HFpEF) dramatically increases with age. Although ageing plays a central role in the development of HFpEF, not all the elderly patients develop clinical HFpEF. Multiple abnormalities in the cardiovascular system have been proposed to contribute to the development of HFpEF. However, the pathophysiology that discriminates between physiological ageing and overt HFpEF is incompletely understood. Purpose The purpose of this study was to assess the effects of ageing on the cardiac structures and haemodynamics. Moreover, we evaluated the determinant factor that discriminates between physiological ageing and overt HFpEF by non-invasive preload increasing manoeuvre using leg-positive pressure (LPP) stress echocardiography. Methods A total of 91 subjects were prospectively recruited in this study: 22 patients with HFpEF and 69 healthy controls. Normal controls were further stratified into 3 age groups: young (n = 19, 20-40 years of age), middle-aged (N = 25, 40-65 years) and elderly (n = 25, &amp;gt;65 years). All subjects underwent LPP stress with a continuous external pressure of 90 mmHg around both lower limbs using dedicated airbags (Fig.). Results The left ventricular mass index (LVMI; young, 68 ± 19 g/m²; middle-age, 70 ± 18 g/m²; elderly, 84 ± 21 g/m²) and also the relative wall thickness (RWT; young, 0.34 ± 0.09; middle-age, 0.41 ± 0.06; elderly 0.55 ± 0.10) increased with ageing, which was accelerated in HFpEF (LVMI: 111 ± 32 g/m², RWT; 0.63 ± 0.19, ANOVA P &amp;lt; 0.001, respectively). Although baseline LV ejection fraction and cardiac output were quite comparable between groups, E/e’ ratio significantly increased with with ageing (ANOVA P &amp;lt; 0.001, Fig.). During LPP stress, E/e’ ratio significantly increased in the middle-aged and elderly groups (from 8.8 ± 2.7 to 9.7 ± 3.3, and from 11.4 ± 2.4 to 13.0 ± 2.2, P &amp;lt; 0.05, respectively), which was further deteriorated in HFpEF (from 16.8 ± 5.8 to 18.0 ± 7.6, P &amp;lt; 0.05). On the other hand, stroke volume index (SVi) significantly increased in each healthy group during LPP stress (young; from 45 ± 10 to 50 ± 11 mL/m², middle-age; from 39 ± 7 to 44 ± 6 mL/m² and elderly; from 37 ± 7 to 43 ± 8 mL/m², all P &amp;lt; 0.001), while SVi failed to increase in the HFpEF group (from 45 ± 13 to 45 ± 14 mL/m², P = 0.60). In a multivariate logistic regression analysis, LVMI (hazard ratio; HR 1.055, P &amp;lt; 0.05), baseline E/e’ (HR 1.444; P &amp;lt; 0.05), and ΔSVi (HR 0.755; P &amp;lt; 0.05) during LPP stress were the independent parameters that characterised overt HFpEF. Conclusions Striking parallels between structure-function alterations were observed in the physiological cardiovascular ageing process, which was further accelerated in patients with HFpEF. Not only structural remodeling and impaired diastolic function, but also impaired systolic reserve during preload stress is important haemodynamic feature that characterise the pathophysiology of HFpEF. Abstract Figure.

Noninvasive Leg-Positive Pressure Stress Echocardiography Reveals Preload Reserve in Adult Patients after Complete Repair of Tetralogy of Fallot

Long-term sequelae such as right ventricular dysfunction and reduced hemodynamic reserve are the main determinants of cardiovascular outcomes after repair of tetralogy of Fallot (TOF). Echocardiographic parameters at rest offer only partial information on impaired hemodynamics in these patients, and data during stress testing are lacking. The leg-positive pressure (LPP) maneuver has recently been reported to be able to apply acute preload stress. The aim of this study was to test the hypothesis that preload reserve is impaired and ventricular interaction is exacerbated in patients with TOF. In this prospective cross-sectional study, we recruited 44 consecutive patients with TOF and 30 normal control subjects. Echocardiography was performed both at rest and during LPP stress, and preload reserve was defined as the change between baseline stroke volume (SV) and that obtained during LPP stress. The eccentricity index was calculated as the ratio of the left ventricular anteroposterior to septal-lateral dimensions to quantify ventricular interaction. LPP stress significantly increased SV from 73±14 to 83±16mL(P<.01) in control subjects, while the increase in SV was significantly blunted (from 75±19 to 79±18mL; P<.01 for interaction) in patients with TOF. The eccentricity index significantly changed during LPP stress in patients with TOF only from 1.07±0.13 to 1.13±0.14 (P<.01 for interaction). Patients with TOF were subdivided into two subgroups on the basis of the median value of increased response in SV (22 with sufficient and 22 with insufficient preload reserve). Multivariate analysis identified significant pulmonary regurgitation as the only independent determinant factor for insufficient preload reserve (odds ratio, 4.57; 95% CI, 1.048-19.90; P=.04). In patients after repair of TOF, ventricular interaction was exacerbated and preload reserve was impaired, especially in patients with significant pulmonary regurgitation. LPP stress testing may direct tailored treatment approaches, risk stratification, and clinical decision-making, such as more aggressive pharmacologic therapy, meticulous outpatient follow-up, or earlier reintervention.

Postural preinspiratory cortical activity, genioglossus activity and fluid shift in awake obstructive sleep apnoea patients

What is the central question of this study? Transition to supine posture induces an inspiratory load associated with cortical activation in awake healthy subjects. Some obstructive sleep apnoea patients exhibit this cortical activity in the sitting position contributing to the arousal-dependent compensation of their upper airway abnormalities. Does a transition to the supine posture in awake obstructive sleep apnoea patients increase this cortical activity? What is the main finding and its importance? The transition to supine posture induces a reduction in the cortical activity despite evidence of an increase in genioglossus activity, suggesting that genioglossus activation is not driven by cortical activity. The anatomy and mechanical properties of the upper airway (UA) depend on posture. Lying in a supine position causes cephalad fluid shift to the neck, thus narrowing the UA and predisposing the individual to obstructive sleep apnoea (OSA). Increased UA dilator muscle activity during wakefulness prevents the UA collapse but the underlying mechanism has not yet been elucidated. In the sitting position during wakefulness, some OSA patients exhibit preinspiratory cortical activity (preinspiratory potential, PIP) probably related to UA abnormalities. The aim of this study was to investigate changes in the preinspiratory cortical activity and UA dilator muscle in OSA patients during postural challenge. An electroencephalogram was used to detect PIP, and the genioglossus electromyographic activity and ventilation were analysed in 17 awake, male OSA patients while they were sitting, just after lying down, and then in response to leg positive pressure to enhance cephalad fluid shift. The prevalence of PIP decreased from 53% (sitting) to 12% (supine) (P=0.002) in association with increased genioglossus activity (tonic from median (25th, 75th centiles) 2.3 (1.8, 2.8)% to 3.6 (1.7, 5.0)% of voluntary deglutition, P=0.019; phasic from 2.3 (1.9, 2.8)% to 3.7 (2.0, 6.1)%, P=0.024), and with increased transcutaneous carbon dioxide pressure (from 43.0 (42.4, 44.2) to 44.6 (43.5, 45.2) mmHg). No change was observed during leg-positive-pressure application. Moving from the sitting position to the supine position reduces respiratory-related premotor cortical activity in awake OSA patients. The concomitant increase in genioglossus activity, therefore, is not driven by cortical respiratory activity.

Clinical application of stress echocardiography for valvular heart disease.

Stress echocardiography is widely used to assess several cardiovascular diseases, including ischemic heart disease, valvular heart disease (VHD), heart failure, congenital heart disease, and pulmonary hypertension. In valvular heart disease with asymptomatic severe or symptomatic non-severe status, stress echocardiography plays a central role in the management. As of 2017, the updated American College of Cardiology/American Heart Association and European Society of Cardiology/European Association for Cardio-Thoracic Surgery VHD guidelines recommended stress testing to (1) confirm symptoms and (2) evaluate the hemodynamic response to exercise. In patients with undetermined VHD severity in the presence of low-flow status, it can also be helpful to determine whether the VHD is severe based on flow-dependent changes in response to stress. The clinical indications of stress echocardiography in VHD have expanded with growing evidence for prognosis and being an early marker for interventions. As a result, demand has increased in major cardiology societies for the standardization of stress echocardiography in VHD. Echocardiographic centers should be aware of the clinical potential of stress echocardiography to ensure its optimal application and performance in VHD. This article reviews the clinical application of stress echocardiography, including dobutamine, semisupine bicycle, treadmill, and leg-positive pressure for VHD patient management, and focuses on the current consensus regarding the use of stress echocardiography in VHD. Stress echocardiography is safe and should be encouraged, especially in heart valve clinics, to understand the complex mechanism in asymptomatic patients.

Postural respiratory-related cortical activation and rostral fluid shift in awake healthy humans.

What is the central question of this study? Moving to supine induces upper airway modifications and a fluid shift to the neck, which represent inspiratory load that predisposes to upper airway collapse.Is there cortical participation in the response to the load induced by transition to a supine posturein awake healthy subjects? What is the main finding and its importance? Moving to supine induces transient cortical activation in awake healthy subjects, with greater fluid shift, supporting possible cortical participation in the response to upper airway load induced by transition to a supine posture. Our findings open new perspectives in the understanding of the pathogenesis of obstructive sleep apnoea. Moving from sitting upright to lying supine causes anatomical modifications and a fluid shift to the neck, which represent inspiratory loads that predispose to upper airway collapse. The pre-inspiratory potential (PIP) corresponds to the cortical activity observed during inspiratory load. In the sitting position during wakefulness, some obstructive sleep apnoea patients exhibit PIP, probably in relationship to upper airway abnormalities. The aim of this study was to investigate whether moving to the supine position induces respiratory-related cortical activation (PIP) in awake healthy subjects. The ECG was analysed to detect PIP, and EMG activity of the genioglossus muscle and ventilation were measured in the sitting position, immediately after moving to the supine position, and during application of leg positive pressure in the supine position to promote fluid shift, which was measured by bioelectrical impedance. Twenty-four subjects were included. From sitting to lying, PIP prevalence increased from 1/24 to 11/24 (P=0.002), and ventilation decreased with no change in genioglossus activity. The fluid shift from sitting to supine was higher in the subjects exhibiting PIP while supine compared with the subjects without PIP [median (25th; 75th centiles) 440(430; 520) versus 320(275; 385)ml, P=0.018], without any other differences. From before to during leg positive pressure, PIP disappeared (P=0.006). These results indicate that moving from sitting to lying induces transient respiratory-related cortical activity in awake healthy subjects with greater fluid shift, supporting possible cortical participation in the response to upper airway loading induced by moving from sitting upright to lying supine. This study offers new perspectives in the understanding of obstructive sleep apnoea pathogenesis.

Echocardiography during preload stress for evaluation of right ventricular contractile reserve and exercise capacity in pulmonary hypertension.

Pulmonary hypertension (PH) is characterized by marked and sustained elevation of pulmonary vascular resistance and pulmonary artery pressure, and subsequent right-sided heart failure. Right ventricular (RV) function and exercise capacity have been recognized as important prognostic factors for PH. Our aim was to investigate RV contractile reserve and exercise capacity during a leg-positive pressure (LPP) maneuver. The study population comprised 43 PH patients and 17 normal controls. All patients underwent echocardiography at rest and during LPP stress. Exercise capacity was assessed by 6-minute walk distance for PH patients. RV relative wall thickness was calculated from dividing by RV free wall thickness by basal RV linear dimensions at end-diastole. RV function was calculated by averaging peak speckle-tracking longitudinal strain from the RV free wall. RV contractile reserve was assessed as the difference in RV free wall strain at rest and during LPP stress. Changes in left ventricular stroke volume (ΔSV) during LPP stress were also calculated. ΔSV and RV contractile reserve of PH patients were significantly lower than of controls (3.6±6.0mL vs 8.5±2.3mL, and 8.2±11.9% vs 14.5±6.6%; both P<0.01). RV contractile reserve of PH patients with ΔSV <3.3mL was significantly lower than of PH patients with ΔSV >3.3mL (3.9±13.2% vs 12.3±8.9%; P=0.02). ΔSV had also significant correlation with 6-minute walk distance (r=0.42, P=0.006). Multivariate regression analysis showed that RV relative wall thickness was an independent determinant parameter of ΔSV during LPP stress for PH patients (β=3.2, P=0.003). Preload stress echocardiography in response to LPP maneuver, a noninvasive and easy-to-use procedure for routine clinical use, proved to be useful for the assessment of RV contractile reserve and exercise capacity of PH patients.

P1610Non-invasive assessment of preload reserve using the leg-positive pressure manoeuvre in patients with repaired tetralogy of Fallot

P1610Non-invasive assessment of preload reserve using the leg-positive pressure manoeuvre in patients with repaired tetralogy of Fallot

A clinical application of preload stress echocardiography for predicting future hemodynamic worsening in patients with early-stage heart failure.

To improve the prognosis of patients with heart failure, risk stratification in their early stage is important. We assessed whether the change in transmitral flow (TMF) velocity pattern during preload augmentation can predict future hemodynamic worsening in early-stage heart failure patients with impaired relaxation TMF pattern. We designed a prospective cohort study that included 155 consecutive patients with impaired relaxation (IR) pattern at rest. Preload stress echocardiography was achieved using leg-positive pressure (LPP), and changes in TMF pattern during the LPP was observed during baseline echocardiographic examination. The patients whose TMF pattern developed to pseudonormal (PN) pattern throughout the study period were classified into the change to PN group, and patients whose TMF pattern stayed in IR pattern were classified into the stay in IR group. The median follow-up period was 17months. The average age was 68±11years old, and 97 patients (63%) were male. Among 155 patients, 27 were classified into the change to PN group. A Cox proportional hazard analysis confirmed that the change in the peak atrial systolic TMF velocity during the LPP (ΔA, hazard ratio=0.58 per 1SD; 95% CI=0.39-0.88, P=0.010) was the powerful independent predictor of change into PN pattern. Kaplan-Meier analysis revealed that the patients with ΔA≤-7cm/s had more likely to develop into PN pattern than patients with ΔA>-7cm/s (P=0.001). Evaluation of a response in TMF during the LPP might provide an incremental diagnostic value to detect future overt heart failure in patients with early-stage heart failure.

Right Ventricular Function and Beneficial Effects of Cardiac Rehabilitation in Patients With Systolic Chronic Heart Failure

BackgroundIt has been recognized that a comprehensive cardiac rehabilitation (CR) program improves mortality in patients with chronic heart failure. On the other hand, the magnitude of the improvement in exercise capacity after CR differs among individuals. The aim of this study was to assess the echocardiographic determinants of responders to CR using preload stress echocardiography. MethodsWe prospectively enrolled 58 chronic heart failure patients with reduced left ventricular ejection fraction (aged 62 ± 11 years; 69% male; left ventricular ejection fraction 43% ± 7%) who had received optimized medical treatment in a CR program for 5 months. We performed preload echocardiographic studies using leg positive pressure (LPP) to assess the echocardiographic parameters during preload augmentation. We defined 41 patients as a development cohort to assess the predictive value of echocardiographic variables. Next, we validated results in the remaining 17 patients as a validation cohort. ResultsIn the development cohort, significant improvement in peak oxygen uptake (VO2) (>10%) after CR was observed in 58% patients. In a multivariable logistic regression model, the significant predictor of improvement in exercise capacity was right ventricular (RV) strain during LPP (odds ratio: 3.96 per 1 standard deviation; P = 0.01). An RV strain value of −16% during LPP had a good sensitivity of 0.79 and a specificity of 0.71 to identify patients with improvement in peak VO2. In the validation cohort, an optimal cutoff value of RV strain value was the same (area under the curve: 0.77, sensitivity: 0.78, specificity: 0.65). ConclusionsRV strain during LPP may be an echocardiographic parameter for assessing beneficial effects of CR.

Noninvasive Assessment of Preload Reserve Enhances Risk Stratification of Patients With Heart Failure With Reduced Ejection Fraction.

The leg-positive pressure maneuver can safely and noninvasively apply preload stress without increase in total body fluid volume. The purpose of this study was to determine whether preload stress could be useful for risk stratification of patients with heart failure with reduced ejection fraction. For this study, 120 consecutive patients with heart failure with reduced ejection fraction were prospectively recruited. The stroke work index was estimated as product of stroke volume index and mean blood pressure, and the E/e' ratio was calculated to estimate ventricular filling pressure. The echocardiographic parameters were obtained both at rest and during leg-positive pressure stress. During the median follow-up period of 20 months, 30 patients developed adverse cardiovascular events. During preload stress, stroke work index increased significantly (from 3280±1371 to 3857±1581 mm Hg·mL/m2; P<0.001) along with minimal changes in ventricular filling pressure (E/e', from 16±10 to 17±9; P<0.05) in patients without cardiovascular events. However, patients with cardiovascular events showed impairment of Frank-Starling mechanism (stroke work index, from 2863±969 to 2903±1084 mm Hg·mL/m2; P=0.70) and a serious increase in E/e' ratio (from 19±11 to 25±14; P<0.001). Both the patients without contractile reserve and those without diastolic reserve exhibited worse event-free survival than the others (P<0.001). In a Cox proportional-hazards analysis, the changes in stroke work index (hazard ratio: 0.44 per 500 mm Hg·mL/m2 increase; P=0.001) and in E/e' (hazard ratio: 2.58 per 5-U increase; P<0.001) were predictors of cardiovascular events. Contractile reserve and diastolic reserve during leg-positive pressure stress are important determinants of cardiovascular outcomes for patients with heart failure with reduced ejection fraction.

Preload Stress Echocardiography Predicts Outcomes in Patients With Preserved Ejection Fraction and Low-Gradient Aortic Stenosis.

The projected aortic valve area (AVAproj) at a normal transvalvular flow rate using dobutamine is helpful to determine the actual severity of aortic stenosis (AS) and to predict risk of adverse events in low-gradient AS cases with unclear surgical indication. Our study aimed to identify the independent and incremental value of preload stress echocardiography-derived AVAproj to predict outcomes in patients with preserved ejection fraction and low-gradient AS. We prospectively performed echocardiographic studies in 79 patients with low-gradient AS (age, 77±7 years; 30% men) with preload stress echocardiography using leg positive pressure. AVAproj was calculated using AVA and transvalvular flow rate at baseline and during leg positive pressure. The primary end point was the decision for aortic valve surgery or cardiac death. During a median period of 19 months, 23 patients had the decision for aortic valve surgery, and none died during follow-up. In a stepwise multivariable analysis, indexed AVAproj (AVAiproj; hazard ratio, 2.00 per 0.1 cm2/m2 decrease; 95% confidence interval, 1.36-2.96; P<0.001) was associated with the primary end point. Using a receiver operating characteristic curve analysis, the best cutoff value of AVAiproj for predicting cardiac events was <0.72 cm2/m2. By incorporating AVAiproj into AVAi at baseline, continuous net reclassification index for cardiac events was 0.48 (P=0.04). In patients with low-gradient AS, indexed AVAproj derived from preload stress echocardiography can be useful to predict risk of adverse events. The present article should be considered as a proof of concept study, and we think that larger multicenter studies are warranted.

RV Myocardial Strain During Pre-Load Augmentation Is Associated With Exercise Capacity in Patients With Chronic HF

ObjectivesThe aim of this study was to assess the relationship between right ventricular (RV) function during pre-load augmentation and exercise tolerance. BackgroundPeak oxygen uptake (VO2) is a strong predictor of mortality in chronic heart failure. Cardiac function during pre-load augmentation is an important part of the phenomenon in the evaluation of exercise capacity. MethodsWe prospectively performed echocardiographic studies in 68 chronic heart failure patients with cardiopulmonary exercise testing (mean age 60 ± 12 years; 69% male). After resting evaluations, echocardiographic parameters were repeated during leg positive pressure (LPP). Exercise capacity was assessed by peak VO2 in all patients (left ventricular ejection fraction: 43 ± 15%). ResultsPatients with severely reduced exercise capacity (peak VO2 <14 ml/kg/min) had significantly lower stroke volume index, left ventricular global longitudinal strain and RV strain and higher filling pressure (E/e’ and pulmonary arterial systolic pressure) than the remainder. Stroke volume index (β = 0.49), global longitudinal strain (β = −0.61), E/e’ (β = −0.32), pulmonary arterial systolic pressure (β = −0.57), and RV strain (β = −0.66) during LPP were independently correlated to peak VO2 (all p < 0.01). RV strain during LPP was the most powerful predictor in identifying patients with severely reduced exercise capacity (cut off value: −17%; sensitivity: 81%; specificity: 88%; areas under the curve: 0.88; p < 0.001) compared with other variables including resting parameters. ConclusionsRV strain during pre-load augmentation correlated independently to peak VO2 and was a powerful predictor in identifying patients with severely reduced exercise capacity.

Significant Prognostic Value of Acute Preload Stress Echocardiography Using Leg-Positive Pressure Maneuver for Patients With Symptomatic Severe Aortic Stenosis Awaiting Aortic Valve Intervention.

Although aortic valve intervention is recommended for virtually all symptomatic patients with aortic stenosis (AS), how urgently the intervention should be performed remains controversial. The aim of this study was thus to determine whether the preload reserve in response to leg-positive pressure (LPP) maneuver could serve for decision-making for AS patients awaiting aortic valve intervention.Methods and Results:Sixty-eight patients with symptomatic AS, who were referred for aortic valve intervention, were recruited. Stroke volume (SV) was assessed by means of pulsed-wave Doppler, and the ratio between transmitral E wave and mitral annular velocity (e') was calculated to estimate ventricular filling pressure. While waiting for intervention, 11 patients experienced preoperative cardiac events. During acute preload stress, forward SV for patients without cardiac events increased significantly (from 43±9 to 49±10 mL/m2, P<0.01) along with a minimal change in filling pressure (E/e': from 20±8 to 21±9, NS). For patients with cardiac events, the Frank-Starling mechanism was significantly impaired (SVi: from 40±9 to 38±7 mL/m2, NS), while filling pressure increased to the critical level (E/e': from 24±8 to 31±8, P<0.001). Both the patients without flow reserve (∆SVi <4.5 mL/m2) and those without diastolic reserve (∆E/e' ≥2.9) exhibited significantly worse event-free survival than the others (P<0.05, respectively). Assessment of preload reserve during LPP stress could facilitate risk stratification of patients with severe AS waiting for aortic valve intervention.

Abstract 13729: Significant Prognostic Values of Acute Preload Stress Echocardiography by Using Leg-positive Pressure Maneuver in Patients With Severe Aortic Stenosis

Introduction: Recently, leg-positive pressure (LPP) maneuver, using customized air-bags inflated both lower limbs to maintain a constant loading pressure (90 mmHg for 5 minutes), is reported to be able to apply acute preload stress non-invasively without significant change in either heart rate or blood pressure. Hypothesis: We hypothesized the ability to utilize the Frank-Starling mechanism without significant increase in left ventricular (LV) filling pressure in response to LPP stress could provide additional prognostic capability for patients with aortic stenosis (AS). Methods: We prospectively recruited 48 patients with severe AS. LV stroke volume (SV) was assessed by means of pulsed-wave Doppler, and then normalized by body surface area (SVi). The ratio of transmitral E wave and mitral annular velocity (e’) was calculated to estimate LV filling pressure. These parameters were obtained both at rest and during LPP stress. Event-free survival was then tracked for 136 days. Results: Eight patients developed adverse cardiac events. During acute preload stress, forward SV increased significantly (SVi : 42±9 to 48±9 ml/m 2 , p&lt;0.001) along with minimal change in LV filling pressure (E/e’: 20±8 to 21±11, n.s.) in patients without cardiac events. On the other hand, Frank-Starling mechanism was significantly impaired (SVi: from 41±10 to 38±8 ml/m 2 ), while LV filling pressure increased to the critical level (E/e’:26±7 to 33±7, p&lt;0.01) in patients with cardiac events. When the patients were divided into two subgroups based on the response to LPP stress, patients without preload reserve (ΔSVi&lt;5ml/m 2 ) showed worse event rate than the others (p&lt;0.05). Similarly, patients without diastolic reserve (ΔE/e’ ratio &gt;3) exhibited significantly worse event-free survival (p&lt;0.05). Conclusions: Assessment of preload reserve and diastolic reserve during LPP stress can enhance the predictive capability for cardiovascular outcomes events for patients with AS.

Pre-Load Stress Echocardiography for Predicting the Prognosis in Mild Heart Failure

ObjectivesThis study sought to introduce and confirm the efficacy of pre-load stress echocardiography with leg-positive pressure (LPP) for improving risk stratification of patients with mild stable heart failure. BackgroundHeart failure patients with mild symptoms and a poor prognosis should be identified and treated aggressively to improve clinical outcome. MethodsWe performed transthoracic echocardiography with LPP in 202 patients with chronic cardiac disease. Twenty-two of these patients also underwent cardiac catheterization, and left ventricular pressure was measured during LPP along with simultaneous Doppler recordings. Patients were classified into 3 groups on the basis of their left ventricular (LV) diastolic dysfunction as assessed by transmitral flow velocity: restrictive or pseudonormal (PN) at rest, impaired relaxation (IR) at rest and during LPP (stable IR), and IR at rest and PN during LPP (unstable IR). Clinical outcome was compared among these groups. ResultsThe LPP increased LV end-diastolic pressure from 15.8 ± 4.7 mm Hg to 20.5 ± 5.0 mm Hg in the unstable IR group and from 10.5 ± 2.6 mm Hg to 14.7 ± 3.8 mm Hg in the stable IR group (both p < 0.001). During an average follow-up of 548 ± 407 days, 5 patients had cardiac death, 37 had acute heart failure, 4 had an acute myocardial infarction, and 7 had a stroke. The all-cause cardiac event rate in unstable IR was higher than in stable IR (p < 0.001), and was similar in the PN group (p = 0.81). Event-free survival was significantly lower in unstable IR than in stable IR (p = 0.003). In a Cox proportional hazards model, unstable IR was an independent predictor of all-cause cardiac events (hazard ratio: 8.0; p < 0.001). ConclusionsThe left LV end-diastolic pressure-volume relationship can be estimated by changes in transmitral flow velocity during LPP. Thus, pre-load stress echocardiography using LPP provides additional prognostic information in mild heart failure beyond that provided by conventional Doppler echocardiography at rest.

Autonomic nervous control of heart rate during blood-flow restricted exercise in man.

Power spectra of instantaneous heart rate (fc) allows the estimation of the contribution of sympathetic and parasympathetic control of fc during steady-state conditions. The present study was designed to examine autonomic control of fc as influenced by normal dynamic leg exercise and by ischemic leg exercise. Eight subjects performed supine cycle ergometry at 30% of their control peak work rate, with and without blood-flow restriction. Blood-flow restriction was induced by exposing the exercising legs to a supra-atmospheric pressure of 6.7 kPa (leg positive pressure; LPP). The exercise responses of arterial pressure and fc increased (P < 0.05) by LPP exposure. The exaggerated pressor response may be attributed to a chemoreflex drive originating in the ischemic muscles. Exposure to LPP during exercise also produced a significant decrease in parasympathetically mediated high frequency (HF; 0.15-1.00 Hz) fluctuation of fc, as indicated by a decrease (P < 0.05) in percent HF power compared to the control exercise level. During LPP exercise, the sympathetically mediated very low frequency (VLF; 0-0.05 Hz) fluctuation of fc increased, as indicated by an increase (P < 0.05) in percent VLF power above control exercise levels. Both LPP and control exercise conditions decreased (P < 0.05) power in all frequency ranges of interest compared to their respective resting conditions. The results suggest that the increase in fc associated with normal dynamic exercise was mediated predominantly by parasympathetic withdrawal, whereas the exaggerated fc response during ischemic exercise resulted from a combination of cardiac sympathetic drive and parasympathetic withdrawal.(ABSTRACT TRUNCATED AT 250 WORDS)

Dynamic exercise in man as influenced by experimental restriction of blood flow in the working muscles.

The effects of reduced muscle perfusion pressure on dynamic exercise performance and cardiovascular and respiratory functions were investigated. Eight subjects were studied during supine cycle ergometry at stepwise increasing workloads until exhaustion with and without the legs exposed to a supra-atmospheric pressure of 50 mmHg (Leg Positive Pressure, LPP), a novel and convenient means of reducing the perfusion pressure in the working muscles. In the LPP condition exercise performance was reduced by 40% which, judging from assessments of perceived exertion, was due to premature muscle fatigue, indicating local or overall underperfusion of the working muscles. At any given work load, the arterial pressure response was considerably stronger during LPP than in the control condition. LPP also caused greater increases in blood lactate concentration and pulmonary ventilation, the differences from control increasing with the work load. Furthermore, the ventilatory equivalent for O2 at a given work load was markedly higher in the LPP than in the control condition, while exercise-induced decreases in end-tidal PCO2 were considerably exaggerated by LPP. The augmented pressor response during flow-restricted exercise, together with the strong ventilatory response which was out of proportion to overall O2 uptake, suggests increased activation of muscle chemoreflexes by accumulation of metabolic end products, the increased pressor response tending to reduce the local flow error in the working muscles.