Cardiac Stasis Imaging, Stroke and Silent Brain Infarcts in Patients with Non-Ischemic Dilated Cardiomyopathy.

Cardioembolic stroke is one of the most devastating complications of non-ischemic dilated cardiomyopathy (NIDCM). However, in clinical trials of primary prevention, the benefits of anticoagulation are hampered by the risk of bleeding. Indices of cardiac blood stasis may account for the risk of stroke and be useful to individualize primary prevention treatments. We performed a cross-sectional study in patients with NIDCM and no history of atrial fibrillation (AF) from two sources: 1) a prospective enrollment of unselected patients with left ventricular (LV) ejection fraction <45% and 2) a retrospective identification of patients with a history of previous cardioembolic neurological event. The primary endpoint integrated a history of ischemic stroke or the presence intraventricular thrombus, or a silent brain infarction (SBI) by imaging. From echocardiography, we calculated blood flow inside the LV, its residence time (RT) maps and its derived stasis indices. Of the 89 recruited patients, 18 showed a positive endpoint: 9 had a history stroke or TIA and 9 were diagnosed with SBIs in the brain imaging. Averaged RT, performed good to identify the primary endpoint (AUC (95% CI)= 0.75 (0.61-0.89), p= 0.001). When accounting only for identifying a history of stroke or TIA, AUC for was 0.92 (0.85-1.00) with and odds ratio= 7.2 (2.3 - 22.3) per cycle, p< 0.001. These results suggest that, in patients with NIDCM in sinus rhythm, stasis imaging derived from echocardiography may account for the burden of stroke.

Clinical evaluation of pulmonary hypertension using patient-reported outcomes: a cross-sectional study.

BACKGROUND: Patients with pulmonary hypertension (PH) have progressive and disabling symptoms, as well as a burden of treatments and a difficult clinical evaluation that make health-related quality of life a particularly relevant endpoint in this disease. The objective of the study was to evaluate patient-reported outcomes of patients receiving specific treatment for PH in a tertiary hospital using a specific questionnaire (Cambridge Pulmonary Hypertension Outcome Review-CAMPHOR) in the pharmacy consultation. METHODS: A cross-sectional, observational, descriptive study was conducted. It included all patients receiving specific treatment for PH in a tertiary hospital in Madrid, Spain. The inclusion period comprised between August to December 2019. CAMPHOR questionnaires containing three domains: symptoms, activities and quality of life were completed by the patients at the pharmacy consultation. Demographic and clinical variables, including WHO Functional Class (WHO FC), PH-specific tests and hemodynamic parameters, were recorded. Non-parametric analyses to assess relations between variables and CAMPHOR domains were performed. RESULTS: Thirty-six patients consented to participate in the study and completed the questionnaire. Median scores for symptoms, activities, and quality of life domains were 5.5 (2.5-10), 8.0 (4.5-10.5) and 3.5 (1-7.5), respectively. Statistically significant differences were found in the three domains when comparing by WHO FC, in the activities domain for 6-m walking test and in the quality of life domain for patients who had emergency visits or hospitalizations in the last year. CONCLUSIONS: The CAMPHOR questionnaire could be useful as a complementary test to achieve an integrated evaluation of PH patients, who could complete it easily during their routine pharmacy visits.

The natural matching of harmonic responses in the pulmonary circulation.

KEY POINTS: The right ventricle of the mammal heart is highly sensitive to the afterload imposed by a combination of the pulmonary circulation and the retrograde contribution of the left heart. Right ventricular afterload can be analysed in terms of pulmonary artery input impedance, which we were able to decompose as the result of the harmonic frequency responses of the pulmonary vessels and the left heart attached in series. Using spectral methods, we found a natural matching between the pulmonary vasculature and the left chambers of the heart. This coupling implies that the upstream transmission of the left heart frequency-response has favourable effects on the pulmonary tree. This physiological mechanism protects the right ventricle against acute changes in preload, and its impairment may be a relevant contribution to right ventricle dysfunction in pulmonary hypertension. ABSTRACT: The right ventricle (RV) of the mammal heart is highly sensitive to the afterload imposed by the pulmonary circulation, and the left heart (LH) retrogradely contributes significantly to this vascular load. Transmission-line theory anticipates that the degree of matching between the frequency responses of the pulmonary vasculature and the LH should modulate the global right haemodynamic burden. We measured simultaneous high-fidelity flow (pulmonary artery) and pressure (pulmonary artery and left atrium) in 18 healthy minipigs under acute haemodynamic interventions. From these data, we decomposed the impedance spectra of the total right-circulation system into the impedance of the pulmonary vessels and the harmonic response of the LH. For frequencies above the first harmonic, total impedance was below the pulmonary impedance during all phases (P < 0.001; pooled phases), demonstrating a favourable effect of the LH harmonic response on RV pulsatile load: the LH harmonic response was responsible for a 20% reduction of pulse pulmonary artery pressure (P < 0.001 vs. a theoretical purely-resistive response) and a 15% increase of pulmonary compliance (P = 0.009). This effect on compliance was highest during acute volume overload. In the normal right circulation, the longitudinal impedance of the pulmonary vasculature is matched to the harmonic response of the LH in a way that efficiently reduces the pulmonary pulsatile vascular load. This source of interaction between the right and left circulations of mammals protects the RV against excessive afterload during acute volume transients and its disruption may be an important contributor to pulmonary hypertension.

Clinical Utility of a Risk-Adapted Protocol for the Evaluation of Coronary Artery Disease in Liver Transplant Recipients.

The prevalence and management of coronary artery disease (CAD) in liver transplantation (LT) candidates are not well characterized. The aims of this study were to evaluate the impact on clinical outcomes of a specifically designed protocol for the management of asymptomatic CAD in LT candidates and to investigate noninvasive risk profiles for obstructive and nonobstructive CAD for 202 LT candidates. Those with high baseline cardiovascular risk (CVR; defined by the presence of classic CVR factors and/or decreased ejection fraction) received coronary angiography and significant arterial stenosis and were treated with percutaneous stents. Patients were followed up after LT until death or coronary event (CE). There were 78 patients who received coronary evaluation (62 direct angiography, 14 computed tomography coronary angiography, and 2 both). Of them, 39 (50%) patients had CAD of any severity, and 6 (7.7%) had significant lesions (5 were amenable to be treated with stents, whereas 1 patient had diffuse lesions which contraindicated the LT). Insulin-dependent diabetes was the only factor related to CAD of any severity (odds ratio, 3.44; 95% confidence interval [CI], 1.00-11.97). A total of 69 patients (46 with coronary evaluation) received LT. The incidence of CEs and overall survival after LT were similar between patients with and without coronary evaluation. Furthermore, no differences occurred between these groups in a multivariate competing risk model (subhazard ratio, 0.84; 95% CI, 0.27-2.61; P = 0.76). In conclusion, the application of an angiographic screening protocol of CAD in a selected high-risk Mediterranean population is safe and effective. The short- and medium-term incidence rates of CEs and death after LT in this population are similar to that observed in low-risk patients.

Sildenafil for improving outcomes in patients with corrected valvular heart disease and persistent pulmonary hypertension: a multicenter, double-blind, randomized clinical trial.

Aims: We aimed to determine whether treatment with sildenafil improves outcomes of patients with persistent pulmonary hypertension (PH) after correction of valvular heart disease (VHD). Methods and results: The sildenafil for improving outcomes after valvular correction (SIOVAC) study was a multricentric, randomized, parallel, and placebo-controlled trial that enrolled stable adults with mean pulmonary artery pressure ≥ 30 mmHg who had undergone a successful valve replacement or repair procedure at least 1 year before inclusion. We assigned 200 patients to receive sildenafil (40 mg three times daily, n = 104) or placebo (n = 96) for 6 months. The primary endpoint was the composite clinical score combining death, hospital admission for heart failure (HF), change in functional class, and patient global self-assessment. Only 27 patients receiving sildenafil improved their composite clinical score, as compared with 44 patients receiving placebo; in contrast 33 patients in the sildenafil group worsened their composite score, as compared with 14 in the placebo group [odds ratio 0.39; 95% confidence interval (CI) 0.22-0.67; P < 0.001]. The Kaplan-Meier estimates for survival without admission due to HF were 0.76 and 0.86 in the sildenafil and placebo groups, respectively (hazard ratio 2.0, 95% CI = 1.0-4.0; log-rank P = 0.044). Changes in 6-min walk test distance, natriuretic peptides, and Doppler-derived systolic pulmonary pressure were similar in both groups. Conclusion: Treatment with sildenafil in patients with persistent PH after successfully corrected VHD is associated to worse clinical outcomes than placebo. Off-label usage of sildenafil for treating this source of left heart disease PH should be avoided. The trial is registered with ClinicalTrials.gov, number NCT00862043.

The Biological Bases of Group 2 Pulmonary Hypertension.

Pulmonary hypertension (PH) is a potentially fatal condition with a prevalence of around 1% in the world population and most commonly caused by left heart disease (PH-LHD). Usually, in PH-LHD, the increase of pulmonary pressure is only conditioned by the retrograde transmission of the left atrial pressure. However, in some cases, the long-term retrograde pressure overload may trigger complex and irreversible biomechanical and biological changes in the pulmonary vasculature. This latter clinical entity, designated as combined pre- and post-capillary PH, is associated with very poor outcomes. The underlying mechanisms of this progression are poorly understood, and most of the current knowledge comes from the field of Group 1-PAH. Treatment is also an unsolved issue in patients with PH-LHD. Targeting the molecular pathways that regulate pulmonary hemodynamics and vascular remodeling has provided excellent results in other forms of PH but has a neutral or detrimental result in patients with PH-LHD. Therefore, a deep and comprehensive biological characterization of PH-LHD is essential to improve the diagnostic and prognostic evaluation of patients and, eventually, identify new therapeutic targets. Ongoing research is aimed at identify candidate genes, variants, non-coding RNAs, and other biomarkers with potential diagnostic and therapeutic implications. In this review, we discuss the state-of-the-art cellular, molecular, genetic, and epigenetic mechanisms potentially involved in PH-LHD. Signaling and effective pathways are particularly emphasized, as well as the current knowledge on -omic biomarkers. Our final aim is to provide readers with the biological foundations on which to ground both clinical and pre-clinical research in the field of PH-LHD.

Stasis imaging predicts the risk of cardioembolic events related to acute myocardial infarction: the ISBITAMI study.

INTRODUCTION AND OBJECTIVES: In the setting of ST-segment elevation myocardial infarction (STEMI), imaging-based biomarkers could be useful for guiding oral anticoagulation to prevent cardioembolism. Our objective was to test the efficacy of intraventricular blood stasis imaging for predicting a composite primary endpoint of cardioembolic risk during the first 6 months after STEMI. METHODS: We designed a prospective clinical study, Imaging Silent Brain Infarct in Acute Myocardial Infarction (ISBITAMI), including patients with a first STEMI, an ejection fraction ≤ 45% and without atrial fibrillation to assess the performance of stasis metrics to predict cardioembolism. Patients underwent ultrasound-based stasis imaging at enrollment followed by heart and brain magnetic resonance at 1-week and 6-month visits. From the stasis maps, we calculated the average residence time, RT, of blood inside the left ventricle and assessed its performance to predict the primary endpoint. The longitudinal strain of the 4 apical segments was quantified by speckle tracking. RESULTS: A total of 66 patients were assigned to the primary endpoint. Of them, 17 patients had 1 or more events: 3 strokes, 5 silent brain infarctions, and 13 mural thromboses. No systemic embolisms were observed. RT (OR, 3.73; 95%CI, 1.75-7.9; P<.001) and apical strain (OR, 1.47; 95%CI, 1.13-1.92; P=.004) showed complementary prognostic value. The bivariate model showed a c-index=0.86 (95%CI, 0.73-0.95), a negative predictive value of 1.00 (95%CI, 0.94-1.00), and positive predictive value of 0.45 (95%CI, 0.37-0.77). The results were confirmed in a multiple imputation sensitivity analysis. Conventional ultrasound-based metrics were of limited predictive value. CONCLUSIONS: In patients with STEMI and left ventricular systolic dysfunction in sinus rhythm, the risk of cardioembolism may be assessed by echocardiography by combining stasis and strain imaging. Registered at ClinicalTrials.gov (NCT02917213).

Increased Chamber Resting Tone Is a Key Determinant of Left Ventricular Diastolic Dysfunction.

BACKGROUND: Twitch-independent tension has been demonstrated in cardiomyocytes, but its role in heart failure (HF) is unclear. We aimed to address twitch-independent tension as a source of diastolic dysfunction by isolating the effects of chamber resting tone (RT) from impaired relaxation and stiffness. METHODS: We invasively monitored pressure-volume data during cardiopulmonary exercise in 20 patients with hypertrophic cardiomyopathy, 17 control subjects, and 35 patients with HF with preserved ejection fraction. To measure RT, we developed a new method to fit continuous pressure-volume measurements, and first validated it in a computational model of loss of cMyBP-C (myosin binding protein-C). RESULTS: In hypertrophic cardiomyopathy, RT (estimated marginal mean [95% CI]) was 3.4 (0.4-6.4) mm Hg, increasing to 18.5 (15.5-21.5) mm Hg with exercise (P<0.001). At peak exercise, RT was responsible for 64% (53%-76%) of end-diastolic pressure, whereas incomplete relaxation and stiffness accounted for the rest. RT correlated with the levels of NT-proBNP (N-terminal pro-B-type natriuretic peptide; R=0.57; P=0.02) and with pulmonary wedge pressure but following different slopes at rest and during exercise (R2=0.49; P<0.001). In controls, RT was 0.0 mm Hg and 1.2 (0.3-2.8) mm Hg in HF with preserved ejection fraction patients and was also exacerbated by exercise. In silico, RT increased in parallel to the loss of cMyBP-C function and correlated with twitch-independent myofilament tension (R=0.997). CONCLUSIONS: Augmented RT is the major cause of LV diastolic chamber dysfunction in hypertrophic cardiomyopathy and HF with preserved ejection fraction. RT transients determine diastolic pressures, pulmonary pressures, and functional capacity to a greater extent than relaxation and stiffness abnormalities. These findings support antimyosin agents for treating HF.

Transvalvular jet velocity, aortic valve area, mortality, and cardiovascular outcomes.

AIMS: The interplay between aortic stenosis (AS), cardiovascular events, and mortality is poorly understood. In addition, how echocardiographic indices compare for predicting outcomes remains unexplored for the full range of AS severity. METHODS AND RESULTS: We prospectively calculated peak jet velocity (Vmax) and aortic valve area (AVA) in 5994 adult subjects with and without AS. We linked ultrasound data to 5-year mortality and clinical events obtained from electronic medical records. Proportional-hazard and negative binomial regression models were adjusted for relevant covariables such as age, sex, comorbidities, stroke-volume, LV ejection fraction, left valve regurgitation, aortic valve sclerosis or calcification, and valve replacement. We observed a strong linear relationship between Vmax and all-cause mortality (hazard ratio: 1.26, 95% confidence interval: 1.19-1.33 per 100 cm/s), cardiovascular events, as well as incidental and recurrent heart failure (HF). Adjusted risks were highly significant even at Vmax values in the range of 150-200 cm/s, risk curves separating very early after the index exam. Vmax was not associated with coronary, arrhythmic, cerebrovascular, or non-cardiovascular events. Although risks were confirmed when AVA was entered in place of Vmax, the risks estimated for categories based on the two indices were mismatched, even in patients with normal flow. An external cohort comprising 112 690 patients confirmed augmented risks of all-cause and cardiovascular mortality starting at values of Vmax and AVA in the range of mild AS. CONCLUSIONS: Aortic stenosis is strongly associated to all-cause mortality, cardiovascular mortality, and cardiac events, specifically HF. Risks increase in parallel to the degree of outflow obstruction but are apparent very early in patients with mild disease. Criteria for grading AS based on Vmax and AVA are mismatched in terms of outcomes.

Impact of interstitial lung disease on the survival of systemic sclerosis with pulmonary arterial hypertension.

To assess severity markers and outcomes of patients with systemic sclerosis (SSc) with or without pulmonary arterial hypertension (PAH-SSc/non-PAH-SSc), and the impact of interstitial lung disease (ILD) on PAH-SSc. Non-PAH-SSc patients from the Spanish SSc registry and PAH-SSc patients from the Spanish PAH registry were included. A total of 364 PAH-SSc and 1589 non-PAH-SSc patients were included. PAH-SSc patients had worse NYHA-functional class (NYHA-FC), worse forced vital capacity (FVC) (81.2 ± 20.6% vs 93.6 ± 20.6%, P < 0.001), worse tricuspid annular plane systolic excursion (TAPSE) (17.4 ± 5.2 mm vs 19.9 ± 6.7 mm, P < 0.001), higher incidence of pericardial effusion (30% vs 5.2%, P < 0.001) and similar prevalence of ILD (41.8% vs. 44.9%). In individuals with PAH-SSc, ILD was associated with worse hemodynamics and pulmonary function tests (PFT). Up-front combination therapy was used in 59.8% and 61.7% of patients with and without ILD, respectively. Five-year transplant-free survival rate was 41.1% in PAH-SSc patients and 93.9% in non-PAH-SSc patients (P < 0.001). Global survival of PAH-SSc patients was not affected by ILD regardless its severity. The multivariate survival analysis in PAH-SSc patients confirmed age at diagnosis, worse NYHA-FC, increased PVR, reduced DLCO, and lower management with up-front combination therapy as major risk factors. In conclusion, in PAH-SSc cohort risk of death was greatly increased by clinical, PFT, and hemodynamic factors, whereas it was decreased by up-front combination therapy. Concomitant ILD worsened hemodynamics and PFT in PAH-SSc but not survival regardless of FVC impairment.

Persistent Pulmonary Hypertension in Corrected Valvular Heart Disease: Hemodynamic Insights and Long-Term Survival.

Background The determinants and consequences of pulmonary hypertension after successfully corrected valvular heart disease remain poorly understood. We aim to clarify the hemodynamic bases and risk factors for mortality in patients with this condition. Methods and Results We analyzed long-term follow-up data of 222 patients with pulmonary hypertension and valvular heart disease successfully corrected at least 1 year before enrollment who had undergone comprehensive hemodynamic and imaging characterization as per the SIOVAC (Sildenafil for Improving Outcomes After Valvular Correction) clinical trial. Median (interquartile range) mean pulmonary pressure was 37 mm Hg (32-44 mm Hg) and pulmonary artery wedge pressure was 23 mm Hg (18-26 mm Hg). Most patients were classified either as having combined precapillary and postcapillary or isolated postcapillary pulmonary hypertension. After a median follow-up of 4.5 years, 91 deaths accounted for 4.21 higher-than-expected mortality in the age-matched population. Risk factors for mortality were male sex, older age, diabetes mellitus, World Health Organization functional class III and higher pulmonary vascular resistance-either measured by catheterization or approximated from ultrasound data. Higher pulmonary vascular resistance was related to diabetes mellitus and smaller residual aortic and mitral valve areas. In turn, the latter correlated with prosthetic nominal size. Six-month changes in the composite clinical score and in the 6-minute walk test distance were related to survival. Conclusions Persistent valvular heart disease-pulmonary hypertension is an ominous disease that is almost universally associated with elevated pulmonary artery wedge pressure. Pulmonary vascular resistance is a major determinant of mortality in this condition and is related to diabetes mellitus and the residual effective area of the corrected valve. These findings have important implications for individualizing valve correction procedures. Registration URL: https://www.clinicaltrials.gov; Unique identifier: NCT00862043.

Rationale and design of the optical coherence tomography observation of pulmonary ultra-structural changes in heart failure (OCTOPUS-CHF) study.

BACKGROUND: The assessment of vascular remodeling using optical coherence tomography (OCT) has been previously described in some types of pulmonary hypertension. However, evidence about its feasibility and clinical utility for evaluation of pulmonary arterial vasculopathy in advanced heart failure (HF) is scarce. Optical Coherence Tomography Observation of Pulmonary Ultra-Structural Changes in Heart Failure (OCTOPUS-CHF) study is designed to study the correlation between OCT-morphometric parameters and hemodynamic data measured or derived from right heart catheterization (RHC). METHODS: OCTOPUS-CHF is an observational, prospective, multicentre study aiming to recruit 100 patients with advanced HF referred for heart transplantation (HTx) evaluation. As part of such evaluation, all patients will undergo RHC in order to rule out severe pulmonary hypertension. After RHC, a Dragonfly™ OPTIS™ imaging catheter will be used to perform OCT evaluation of a right-lower-lobe pulmonary artery with a luminal diameter ≤ 5 mm. The primary objective is to study the correlation of OCT parameters with hemodynamic RHC data. The secondary objective is to determine if OCT parameters improve prognostic stratification. CONCLUSIONS: The OCTOPUS-CHF study will investigate the feasibility and clinical utility of pulmonary arterial vasculopathy evaluation with OCT in advanced HF patients and its correlation with hemodynamic RHC data. The ability of OCT-morphometric parameters to improve prognostic stratification will also be tested.

Valve area and the risk of overestimating aortic stenosis.

OBJECTIVE: To obtain reference values of aortic valve area (AVA) in a large population and to infer the risk of overestimating aortic stenosis (AS) when focusing on flow-corrected indices of severity. METHODS: We prospectively measured indices of AS in all consecutive echocardiograms performed in a large referral cardiac imaging laboratory for 1 year. We specifically analysed the distribution of AVA, indexed AVA and velocity ratio (Vratio) in patients with and without AS, the latter defined as the coexistence of valvular outflow obstruction (Vmax ≥2.5 m/s) and morphological findings of valve degeneration. RESULTS: 16 156 echocardiograms were analysed, 14 669 of which did not show valvular obstruction (peak jet velocity <2.5 m/s). In the latter group, AVA was 2.6±0.7 cm2 in 8190 studies with normal valves and 2.3±0.7 cm2 in 6479 studies with aortic sclerosis (AScl). There was a relatively wide overlap between values of AVA, indexed AVA and velocity ratio between studies of patients with AScl and AS. Values of AVA ≤1.0 cm2 were found in 0.5% of studies with normal valves and 1.8% of studies with AScl. These proportions were 3.1% and 9.3% for AVA ≤1.5 cm2, respectively. Vratio ≤0.25 were found in 0.1% of patients without obstruction. Risk factors for a small AVA in patients without obstruction were AScl, female sex, small body surface area, low ejection fraction and mitral regurgitation. CONCLUSIONS: Normal values of continuity-equation derived AVA are smaller than previously considered. AVA values below cutoffs of moderate or severe AS can be found in patients without the disease. Flow-corrected indices may overestimate AS in patients with low gradients, particularly in the presence of well-identified risk factors.

Systemic vascular load in calcific degenerative aortic valve stenosis: insight from percutaneous valve replacement.

BACKGROUND: Systemic arterial load impacts the symptomatic status and outcome of patients with calcific degenerative aortic stenosis (AS). However, assessing vascular properties is challenging because the arterial tree's behavior could be influenced by the valvular obstruction. OBJECTIVES: This study sought to characterize the interaction between valvular and vascular functions in patients with AS by using transcatheter aortic valve replacement (TAVR) as a clinical model of isolated intervention. METHODS: Aortic pressure and flow were measured simultaneously using high-fidelity sensors in 23 patients (mean 79 ± 7 years of age) before and after TAVR. Blood pressure and clinical response were registered at 6-month follow-up. RESULTS: Systolic and pulse arterial pressures, as well as indices of vascular function (vascular resistance, aortic input impedance, compliance, and arterial elastance), were significantly modified by TAVR, exhibiting stiffer vascular behavior post-intervention (all, p < 0.05). Peak left ventricular pressure decreased after TAVR (186 ± 36 mm Hg vs. 162 ± 23 mm Hg, respectively; p = 0.003) but remained at >140 mm Hg in 70% of patients. Wave intensity analysis showed abnormally low forward and backward compression waves at baseline, increasing significantly after TAVR. Stroke volume decreased (-21 ± 19%; p < 0.001) and correlated with continuous and pulsatile indices of arterial load. In the 48 h following TAVR, a hypertensive response was observed in 12 patients (52%), and after 6-month follow-up, 5 patients required further intensification of discharge antihypertensive therapy. CONCLUSIONS: Vascular function in calcific degenerative AS is conditioned by the upstream valvular obstruction that dampens forward and backward compression waves in the arterial tree. An increase in vascular load after TAVR limits the procedure's acute afterload relief.

The role of elastic restoring forces in right-ventricular filling.

AIMS: The physiological determinants of RV diastolic function remain poorly understood. We aimed to quantify the contribution of elastic recoil to RV filling and determine its sensitivity to interventricular interaction. METHODS AND RESULTS: High-fidelity pressure-volume loops and simultaneous 3-dimensional ultrasound sequences were obtained in 13 pigs undergoing inotropic modulation, volume overload, and acute pressure overload induced by endotoxin infusion. Using a validated method, we isolated elastic restoring forces from ongoing relaxation using conventional pressure-volume data. The RV contracted below the equilibrium volume in >75% of the data sets. Consequently, elastic recoil generated strong sub-atmospheric passive pressure at the onset of diastole [-3 (-4 to -2) mmHg at baseline]. Stronger restoring suction pressure was related to a shorter isovolumic relaxation period, a higher rapid filling fraction, and lower atrial pressures (all P < 0.05). Restoring forces were mostly determined by the position of operating volumes around the equilibrium volume. By this mechanism, the negative inotropic effect of beta-blockade reduced and sometimes abolished restoring forces. During acute pressure overload, restoring forces initially decreased, but recovered at advanced stages. This biphasic response was related to alterations of septal curvature induced by changes in the diastolic LV-RV pressure balance. The constant of elastic recoil was closely related to the constant of passive stiffness (R = 0.69). CONCLUSION: The RV works as a suction pump, exploiting contraction energy to facilitate filling by means of strong elastic recoil. Restoring forces are influenced by the inotropic state and RV conformational changes mediated by direct ventricular interdependence.

Noninvasive estimation of the rate of relaxation by the analysis of intraventricular pressure gradients.

BACKGROUND: During late ejection, myocardial relaxation causes systolic flow to decelerate and stop, and this phenomenon is coupled with the generation of a pressure gradient inside the left ventricle (LV). We hypothesized that the peak reverse ejection intraventricular pressure difference (REIVPD) between the LV apex and the outflow tract could be a useful method to improve the assessment of LV relaxation using Doppler echocardiography. METHODS AND RESULTS: Three sets of animal experiments and 1 clinical study were designed. In 6 pigs, a close relationship between REIVPD and the intensity of the relaxation wave (R(rm)=0.89) was demonstrated using wave intensity analysis of high-fidelity pressure-volume-velocity data. In 19 animals, REIVPD sensitively detected modifications of the lusotropic state and closely correlated with the time constant of LV relaxation (τ) within animals (R(rm)=-0.93). Load-dependence analysis in 5 pigs showed that REIVPD remained stable up to values of 35% to 40% acute preload reduction. Clinical validation was tested in 50 patients (23 with normal systolic function) undergoing simultaneous Doppler echocardiography and high-fidelity LV pressure measurements on the same beat. REIVPD and tissue Doppler mitral annulus velocity (e') were independently related to τ, but the REIVPD · e' product correlated better with τ than either variable separately (bootstrap-corrected correlation coefficients: R=-0.84 versus -0.71, and -0.70, respectively, P<0.05). Area under the receiver operating characteristic curve to predict impaired relaxation (τ>50 ms) for e' · REIVPD was 0.96 (95% confidence interval, 0.85 to 0.99). CONCLUSIONS: The Doppler-derived REIVPD provides a sensitive, reliable, reproducible, and relatively load-independent index of the rate of LV relaxation. Combined with tissue Doppler measurements of longitudinal function, this method improves noninvasive assessment of LV relaxation in the clinical setting.