Pulmonary circulation at exercise

The pulmonary circulation is a high-flow and low-pressure circuit, with an average resistance of 1 mmHg/min/L in young adults, increasing to 2.5 mmHg/min/L over four to six decades of life. Pulmonary vascular mechanics at exercise are best described by distensible models. Exercise does not appear to affect the time constant of the pulmonary circulation or the longitudinal distribution of resistances. Very high flows are associated with high capillary pressures, up to a 20 to 25 mmHg threshold associated with interstitial lung edema and altered ventilation/perfusion relationships. Pulmonary artery pressures of 40 to 50 mmHg, which can be achieved at maximal exercise, may correspond to the extreme of tolerable right ventricular afterload. Distension of capillaries that decrease resistance may be of adaptative value during exercise, but this is limited by hypoxemia from altered diffusion/perfusion relationships. Exercise in hypoxia is associated with higher pulmonary vascular pressures and lower maximal cardiac output, with increased likelihood of right ventricular function limitation and altered gas exchange by interstitial lung edema. Pharmacological interventions aimed at the reduction of pulmonary vascular tone have little effect on pulmonary vascular pressure-flow relationships in normoxia, but may decrease resistance in hypoxia, unloading the right ventricle and thereby improving exercise capacity. Exercise in patients with pulmonary hypertension is associated with sharp increases in pulmonary artery pressure and a right ventricular limitation of aerobic capacity. Exercise stress testing to determine multipoint pulmonary vascular pressures-flow relationships may uncover early stage pulmonary vascular disease.

Right Atrial Pressure in the Critically Ill: How to Measure, What Is the Value, What Are the Limitations?

Right atrial pressure (P_ra) is determined by the interaction of the function of the heart as a pump, which is called cardiac function, and the factors that determine the return of blood to the heart, which is called return function. Thus, monitoring P_ra or its surrogate, central venous pressure (CVP), can give important insights into mechanisms behind changes in hemodynamic status, responses to interventions, and the likelihood of diagnoses. Examination of the components of the P_ra tracing, especially during the ventilator cycle, can also give information about right-sided cardiac diastolic function, the status of the tricuspid valve, volume responsiveness, and the cardiac rhythm. Importantly, the pressure difference from the large venous reservoir to the heart is small, and thus great care must be taken with technical factors that affect the measurement.

Central and Peripheral Determinants of Exercise Capacity in Heart Failure Patients With Preserved Ejection Fraction

OBJECTIVES

This study sought to discern which central (e.g., heart rate, stroke volume [SV], filling pressure) and peripheral factors (e.g., oxygen use by skeletal muscle, body mass index [BMI]) during exercise were most strongly associated with the presence of heart failure and preserved ejection fraction (HFpEF) as compared with healthy control subjects exercising at the same workload.

BACKGROUND

The underlying mechanisms limiting exercise capacity in patients with HFpEF are not fully understood.

METHODS

In patients with HFpEF (n = 108), the hemodynamic response at peak exercise was measured using right-sided heart catheterization and was compared with that in healthy control subjects (n = 42) at matched workloads to reveal hemodynamic differences that were not attributable to the workload performed. The patients studied were prospectively included in the REDUCE-LAP HF (Reduce Elevated Left Atrial Pressure in Patients With Heart Failure) trials and HemReX (Effect of Age on the Hemodynamic Response During Rest and Exercise in Healthy Humans) study. Univariable and multivariable logistic regression models were used to analyze variables associated with HFpEF versus control subjects.

RESULTS

Compared with healthy control subjects, pulmonary capillary wedge pressure (PCWP) and SV were the only independent hemodynamic variables that were associated with HFpEF, a finding explaining 66% (p < 0.0001) of the difference between the groups. When relevant baseline characteristics were added to the base model, only BMI emerged as an additional independent variable, in total explaining of 90% of the differences between groups (p < 0.0001): PCWP (47%), BMI (31%), and SV (12%).

CONCLUSIONS

The study identified 3 key variables (PCWP, BMI, and SV) that independently correlate with the presence of patients with HFpEF compared with healthy control subjects exercising at the same workload. Therapies that decrease left-sided heart filling pressures could improve exercise capacity and possibly prognosis.

Pathophysiologic and Prognostic Implications of Right Atrial Hypertension in Adults With Tetralogy of Fallot

Background Right atrial pressure (RAP), a composite metric of right ventricular diastolic function, volume status, and right heart compliance, is a predictor of mortality in patients with heart failure due to acquired heart disease. Because patients with tetralogy of Fallot (TOF) might have abnormal right atrial and ventricular mechanics caused by myocardial injury and remodeling, we hypothesized that RAP would be associated with disease severity and cardiovascular adverse events in this population. Methods and Results We performed a cohort study of adults with TOF who underwent right heart catheterization at the Mayo Clinic Rochester between 1990 and 2017. The objective was to determine the association between RAP and multiple domains of disease severity in TOF (percentage of predicted peak oxygen consumption, atrial or ventricular arrhythmia, and heart failure hospitalization), as well as cardiovascular adverse events, defined as sustained ventricular tachycardia, resuscitated or aborted sudden death, heart transplantation, or death. Among 225 patients (113 male; mean age: 39±14 years), mean RAP was 10.7±5.2 mm Hg and median was 10 mm Hg (interquartile range: 7-13 mm Hg). Increasing RAP was associated with atrial or ventricular arrhythmias (odds ratio: 5.01; 95% CI, 1.22-23.49; P<0.001), heart failure hospitalization (odds ratio: 1.47; 95% CI, 1.10-2.39; P=0.033) per 5 mm Hg, and worsening exercise capacity (peak oxygen consumption; R2=0.74, r=-0.86, P<0.001). RAP was a predictor of cardiovascular adverse events (hazard ratio: 1.28; 95% CI, 1.10-1.47; P=0.028) per 5 mm Hg. Conclusions In symptomatic patients with TOF, increasing RAP correlates with multiple domains of disease severity (risk stratification) and predicts future cardiovascular events (prognostication). These data have potential clinical implications in the target population of symptomatic TOF patients.

The prognostic value of the relationship between right atrial and pulmonary capillary wedge pressure in diverse cardiovascular conditions

BACKGROUND

Physical examination of jugular venous pressure is used to estimate right atrial (RA) pressure and infer left-sided filling pressure to assist volume management. Previous studies in advanced heart failure patients showed about 75% concordance between RA and pulmonary capillary wedge (PCW) pressures. We sought to determine the relationship between mean RA and mean PCW pressure and assess the clinical significance in a broad population of patients undergoing invasive right heart catheterization (RHC).

METHODS

We examined 4135 RHC cases at a single academic medical center from February 2007 to December 2014, analyzing baseline variables, hemodynamic data, and in-hospital mortality.

RESULTS

The overall Pearson correlation for mean RA and PCW pressures was 0.68 with 70% concordance between dichotomized pressures (RA ≥10 and PCW ≥22 mmHg). Results were similar in subgroups with heart failure (r=0.67, 72%), STEMI/NSTEMI (r=0.60, 69%), unstable angina (r=0.78, 69%), stable/no angina (r=0.72, 67%), and valvular disease (r=0.61, 72%; Chi-square P=.15). Mean RA pressure was independently associated with in-hospital mortality in multivariate analysis (OR 1.12 [95% CI 1.081-1.157] per 1 mmHg increase, P<.001). The RA/PCW ratio was not independently associated with in-hospital mortality. Mean RA pressure was also weakly associated with worse renal function (rho=-0.16, P<.001).

CONCLUSION

In patients undergoing right catheterization for diverse indications, the mean RA and PCW pressures correlated moderately well, but there was discordance in a sizable minority, in whom assessment of left-sided filling pressures using estimated jugular venous pressure may be misleading. Elevated right atrial pressure is a marker for in-hospital mortality.

The pulmonary capillary wedge pressure accurately reflects both normal and elevated left atrial pressure

BACKGROUND

Pulmonary capillary wedge pressure (PCWP) is routinely used as an indirect measure of the left atrial pressure (LAP), although the accuracy of this estimate, especially under pathological hemodynamic conditions, remains controversial.

OBJECTIVES

The aim of this prospective study was to investigate the reliability of PCWP for the evaluation of LAP under different hemodynamic conditions.

METHODS

Simultaneous left and right heart catheterization data of 117 patients with pure mitral stenosis, obtained before and immediately after percutaneous mitral comissurotomy, were analyzed.

RESULTS

A strong correlation and agreement between PCWP and LAP measurements was demonstrated (correlation coefficient = 0.97, mean bias ± CI, 0.3 ± -3.7 to 4.2 mm Hg). Comparison of measurements performed within a 5-minute interval and those performed simultaneously revealed that simultaneous pressure acquisition yielded better agreement between the 2 methods (bias ± CI, 1.82 ± 1.98 mm Hg). In contrast to previous observations, the discrepancy between the 2 measures did not increase with elevated PCWP. Multiple regression analysis failed to identify hemodynamic confounders of the discrepancy between the 2 pressures. The ability of PCWP to distinguish between normal and elevated LAP (cutoff set at 12 and 15 mm Hg, respectively), as tested by receiver operating characteristics analysis, demonstrated a remarkably high diagnostic accuracy (area under the curve: 0.989 and 0.996, respectively).

CONCLUSIONS

Although the described limits of agreement may not allow the interchangeability of PCWP and LAP, especially at lower pressure ranges, our data support the clinical use of PCWP as a robust and accurate estimate of LAP.

Initial in vitro testing of a paediatric continuous-flow total artificial heart

OBJECTIVES

Mechanical circulatory support has become standard therapy for adult patients with end-stage heart failure; however, in paediatric patients with congenital heart disease, the options for chronic mechanical circulatory support are limited to paracorporeal devices or off-label use of devices intended for implantation in adults. Congenital heart disease and cardiomyopathy often involve both the left and right ventricles; in such cases, heart transplantation, a biventricular assist device or a total artificial heart is needed to adequately sustain both pulmonary and systemic circulations. We aimed to evaluate the in vitro performance of the initial prototype of our paediatric continuous-flow total artificial heart.

METHODS

The paediatric continuous-flow total artificial heart pump was downsized from the adult continuous-flow total artificial heart configuration by a scale factor of 0.70 (1/3 of total volume) to enable implantation in infants. System performance of this prototype was evaluated using the continuous-flow total artificial heart mock loop set to mimic paediatric circulation. We generated maps of pump performance and atrial pressure differences over a wide range of systemic vascular resistance/pulmonary vascular resistance and pump speeds.

RESULTS

Performance data indicated left pump flow range of 0.4-4.7 l/min at 100 mmHg delta pressure. The left/right atrial pressure difference was maintained within ±5 mmHg with systemic vascular resistance/pulmonary vascular resistance ratios between 1.4 and 35, with/without pump speed modulation, verifying expected passive self-regulation of atrial pressure balance.

CONCLUSIONS

The paediatric continuous-flow total artificial heart prototype met design requirements for self-regulation and performance; in vivo pump performance studies are ongoing.

Right Atrial Pressure During Exercise Predicts Survival in Patients With Pulmonary Hypertension

Background We investigated changes in right atrial pressure (RAP) during exercise and their prognostic significance in patients assessed for pulmonary hypertension (PH). Methods and Results Consecutive right heart catheterization data, including RAP recorded during supine, stepwise cycle exercise in 270 patients evaluated for PH, were analyzed retrospectively and compared among groups of patients with PH (mean pulmonary artery pressure [mPAP] ≥25 mm Hg), exercise-induced PH (exPH; resting mPAP <25 mm Hg, exercise mPAP >30 mm Hg, and mPAP/cardiac output >3 Wood Units (WU)), and without PH (noPH). We investigated RAP changes during exercise and survival over a median (quartiles) observation period of 3.7 (2.8-5.6) years. In 152 patients with PH, 58 with exPH, and 60 with noPH, median (quartiles) resting RAP was 8 (6-11), 6 (4-8), and 6 (4-8) mm Hg (P<0.005 for noPH and exPH versus PH). Corresponding peak changes (95% CI) in RAP during exercise were 5 (4-6), 3 (2-4), and -1 (-2 to 0) mm Hg (noPH versus PH P<0.001, noPH versus exPH P=0.027). RAP increase during exercise correlated with mPAP/cardiac output increase (r=0.528, P<0.001). The risk of death or lung transplantation was higher in patients with exercise-induced RAP increase (hazard ratio, 4.24; 95% CI, 1.69-10.64; P=0.002) compared with patients with unaltered or decreasing RAP during exercise. Conclusions In patients evaluated for PH, RAP during exercise should not be assumed as constant. RAP increase during exercise, as observed in exPH and PH, reflects hemodynamic impairment and poor prognosis. Therefore, our data suggest that changes in RAP during exercise right heart catheterization are clinically important indexes of the cardiovascular function.

Liver stiffness obtained by ElastPQ ultrasound shear wave elastography independently determines mean right atrial pressure

PURPOSE

We aimed to investigate the relationship between right atrial pressure (RAP) and liver stiffness (LS) determined by liver elastography (LE) during cardiac resynchronization therapy (CRT) in patients with heart failure (HF) and conventional pacemaker (PM) implantation in patients without HF.

METHODS

60 patients with HF who underwent CRT and 60 patients without HF who underwent PM were enrolled. Routine echocardiography and laboratory examinations were performed. Systolic, diastolic, and mean RAP measurements were performed inversely during PM implantation and LS measurement with ElastPQ technique.

RESULTS

Systolic, diastolic, and mean RAP, left ventricular (LV) systolic-diastolic, right ventricular (RV) diastolic and left atrial diameters, tricuspid regurgitation pressure gradient, and RV-myocardial performance index (MPI) values were significantly higher in patients with HF (p < 0.05 each-one). LV ejection fraction and tricuspid annular plane systolic excursion values were significantly lower in patients with HF group (p < 0.05 each-one). LS values and inspiratory (Ins) and expiratory inferior vena cava (IVC) diameters were significantly higher in the patients with HF (p < 0.05 each-one). Mean RAP was found to be closely related to LS value, Ins-IVC diameter, RV-MPI, and NT-proBNP levels. LS value and Ins-IVC diameter were found to determine patients with mean RAP > 5 mmHg and > 10 mmHg. When the cut-off value of LS was taken as 7 kPa, it was found that the mean RAP > 10 mmHg with 89.6% sensitivity and 87.5% specificity.

CONCLUSIONS

The non-invasive LS value determined by LE independently determines the mean RAP in patients with and without HF. According to our study results, > 7 kPa value for LS determined in liver US may be predictive for increased mean RAP.

Non-invasive Estimation of Right Atrial Pressure Using Inferior Vena Cava Echography

The pulsatility of the inferior vena cava (IVC) reflects the volume status and central venous pressure of patients. The standard clinical indicator of IVC pulsatility is the caval index (CI), measured from ultrasound recordings. However, its estimation is not standardized and is vulnerable to artifacts, mostly because of IVC movements during respiration. Thus, we used a (recently patented) semi-automated method that tracks IVC movements and averages the CI across an entire section of the vein, which provides a more stable indication of pulsatility. This algorithm was used to estimate the CI, pulsatility indicators reflecting either respiratory or cardiac stimulation and the mean diameter of the IVC. These IVC indices, together with anthropometric information, were used as potential features to build an innovative model for the estimation of the right atrial pressure (RAP) recorded from 49 catheterized patients. An exhaustive search was carried out for the best among all possible models that could be obtained by using combinations of these features. The model with minimum estimation error (tested with a leave-one-out approach) was selected. This model estimated RAP with an error of about 3.6 ± 2.6 mm Hg (mean ± standard deviation); the error when using only operator measured variables, without software, was about 4.0 ± 2.5 mm Hg. These promising results underline the need for further study of our RAP estimation method on a larger data set.

Cardiac index predicts long-term outcomes in patients with heart failure

BACKGROUND

The role of cardiac index (CI) and right atrial pressure (RAP) for predicting long-term outcomes of heart failure has not been well established. The aim of this study was to investigate long-term cardiac outcomes in patients with heart failure having various combinations of CI and RAP.

METHODS

A total of 787 heart failure patients who underwent right-heart catheterization were retrospectively categorized into the following four groups: Preserved CI (≥2.5 L/min/m2) and Low RAP (<8 mmHg) (PRE-CI/L-RAP; n = 285); Preserved CI (≥2.5 L/min/m2) and High RAP (≥8 mmHg) (PRE-CI/H-RAP; n = 242); Reduced CI (<2.5 L/min/m2) and Low RAP (<8 mmHg) (RED-CI/L-RAP; n = 123); and Reduced CI (<2.5 L/min/m2) and High RAP (≥8 mmHg) (RED-CI/H-RAP; n = 137). Survival analysis was applied to investigate which groups were associated with major adverse cardiovascular events (MACE).

RESULTS

The RED-CI/L-RAP and RED-CI/H-RAP groups were significantly associated with MACE as compared with the PRE-CI/L-RAP and PRE-CI/H-RAP groups after adjustment for confounding factors (RED-CI/L-RAP vs. PRE-CI/L-RAP: HR 2.11 [95% CI 1.33-3.37], p = 0.002; RED-CI/H-RAP vs. PRE-CI/L-RAP: HR 2.18 [95% CI 1.37-3.49], p = 0.001; RED-CI/L-RAP vs. PRE-CI/H-RAP: HR 1.86 [95% CI 1.16-3.00], p = 0.01; RED-CI/H-RAP vs. PRE-CI/H-RAP: HR 1.92 [95% CI 1.26-2.92], p = 0.002), whereas the difference between the RED-CI/H-RAP and RED-CI/L-RAP groups was not significant (HR 1.03 [95% CI 0.64-1.66], p = 0.89).

CONCLUSIONS

The hemodynamic severity categorized by CI and RAP levels provided clear risk stratification in patients with symptomatic heart failure. Low CI was an independent predictor of long-term cardiac outcomes.

Device therapy with interatrial shunt devices for heart failure with preserved ejection fraction

Heart failure with preserved ejection fraction is responsible for half of all heart failure and confers substantial morbidity and mortality, and yet to date, there have been no effective pharmacologic interventions. Although the pathophysiology is complex, the primary aetiology of exercise intolerance is due to an elevated left atrial pressure, particularly with exercise. In this context, device-based therapy has become a focus. Several companies have developed techniques to percutaneously create an iatrogenic left to right shunt at the atrial level, thereby reducing left atrial pressure and reducing transmitted pressures to the pulmonary circulation and reducing pulmonary congestion. In this review, we explore the pathophysiology, evidence base, benefits, and considerations of these devices and their place in the therapeutic landscape of heart failure with preserved ejection fraction.

Ratio of Systolic Blood Pressure to Right Atrial Pressure, a Novel Marker to Predict Morbidity and Mortality in Acute Systolic Heart Failure

Congestion is the main contributor to heart failure (HF) morbidity and mortality. We assessed the combined role of congestion and decreased forward flow in predicting morbidity and mortality in acute systolic HF. The Evaluation Study of Congestive Heart Failure and Pulmonary Artery Catheterization Effectiveness trial data set was used to determine if the ratio of simultaneously measured systolic blood pressure (SBP)/right atrial pressure (RAP) on admission predicted HF rehospitalization and 6-month mortality. One hundred ninety-five patients (mean age 56.5 years, 75% men) who received pulmonary artery catheterization were studied. The RAP, SBP, and SBP/RAP had an area under the curve (AUC) of 0.593 (p = 0.0205), 0.585 (p = 0.0359), and 0.621 (p = 0.0026), respectively, in predicting HF rehospitalization. The SBP/RAP was a superior marker of HF rehospitalization compared with RAP alone (difference in AUC 0.0289, p = 0.0385). The optimal criterion of SBP/RAP <11 provided the highest combined sensitivity (77.1%) and specificity (50.9%) in predicting HF rehospitalization. The SBP/RAP had an AUC 0.622, p = 0.0108, and a cut-off value of SBP/RAP <8 had a sensitivity of 61.9% and specificity 64.1% in predicting mortality. Multivariate analysis showed that an SBP/RAP <11 independently predicted rehospitalization for HF (estimated odds ratio 3.318, 95% confidence interval 1.692 to 6.506, p = 0.0005) and an SBP/RAP <8 independently predicted mortality (estimated hazard ratio 2.025, 95% confidence interval 1.069 to 3.833, p = 0.030). In conclusion, SBP/RAP ratio is a marker that identifies a spectrum of complications after hospitalization of patients with decompensated systolic HF, starting with increased incidence of HF rehospitalization at SBP/RAP <11 to increased mortality with SBP/RAP <8.

Determinants of invasive left atrial pressure in patients with atrial fibrillation

AIMS

Estimation of left ventricular (LV) filling pressures in patients with a history of atrial fibrillation (AF) is challenging due to lack of reliable parameters. This study investigates the association between cardiac structure and function and invasive mean left atrial pressure (LAP).

METHODS AND RESULTS

This is a multi-centre prospective study enrolling patients undergoing transcatheter ablation for AF. The invasive measurement of LAP was performed at the time of the procedure while the echocardiography within the previous 24 h. A mean LAP ≥ 15 mmHg was considered as increased. Overall, 101 patients were included (mean age 65.8 ± 8.5 years, 68% male, mean LV ejection fraction 56.6 ± 8.0%). No significant differences regarding clinical characteristics were detected between the group of patients with normal (n = 47) or increased LAP (n = 54). The latter showed lower values of LV global longitudinal strain, larger left atrial volumes (LAVs) and worse right ventricular (RV) function. After multivariable adjustment, higher E/e' ratio (P = 0.041) and minimal LAV index (LAVI min) (P = 0.031), lower peak atrial longitudinal strain (P = 0.030), and RV free wall longitudinal strain (P = 0.037), but not maximal LAV index (LAVI max) (P = 0.137), were significantly associated with mean LAP. The associations were not modified by cardiac rhythm. Overall, LAVI min showed the best diagnostic accuracy to predict elevated LAP (area under the curve 0.703).

CONCLUSION

LA structure and function assessment well correlates with mean LAP in patients with a history of AF. These measures may be used in the assessment of filling pressure in these patients.

Duty cycle of 33% increases cardiac output during cardiopulmonary resuscitation

BACKGROUND

The aim of this study was to investigate whether 33% duty cycle increases end-tidal carbon dioxide (ETCO2) level, a surrogate measurement for cardiac output during cardiopulmonary resuscitation (CPR), compared with 50% duty cycle.

METHODS

Six pigs were randomly assigned to the DC33 or DC50 group. After 3 min of induced ventricular fibrillation (VF), CPR was performed for 5 min with 33% duty cycle (DC33 group) or with 50% duty cycle (DC50 group) (phase I). Defibrillation was delivered until return of spontaneous circulation (ROSC) thereafter. After 30 min of stabilization, the animals were re-assigned to the opposite groups. VF was induced again, and CPR was performed (phase II). The primary outcome was ETCO2 during CPR, and the secondary outcomes were coronary perfusion pressure (CPP), systolic arterial pressure (SAP), diastolic arterial pressure (DAP), and right atrial pressure (RAP).

RESULTS

Mean ETCO2 was higher in the DC33 group compared with the DC50 group (22.5 mmHg vs 21.5 mmHg, P = 0.018). In a linear mixed model, 33% duty cycle increased ETCO2 by 1.0 mmHg compared with 50% duty cycle (P < 0.001). ETCO2 increased over time in the DC33 group [0.6 mmHg/min] while ETCO2 decreased in the DC50 group [-0.6 mmHg/min] (P < 0.001). Duty cycle of 33% increased SAP (6.0 mmHg, P < 0.001), DAP (8.9 mmHg, P < 0.001) RAP (2.6 mmHg, P < 0.001) and CPP (4.7 mmHg, P < 0.001) compared with the duty cycle of 50%.

CONCLUSION

Duty cycle of 33% increased ETCO2, a surrogate measurement for cardiac output during CPR, compared with duty cycle of 50%. Moreover, ETCO2 increased over time during CPR with 33% duty cycle while ETCO2 decreased with 50% duty cycle.

Relation Between Pulmonary Venous Flow and Left Atrial Pressure During Percutaneous Mitral Valve Repair With the MitraClip

Pulmonary venous (PV) flow may provide valuable information in terms of the severity of mitral regurgitation and left atrial (LA) pressure. We sought to find PV flow determinants of LA pressure during MitraClip procedure. We analyzed 575 PV flows in 290 patients using transesophageal echocardiography before and after MitraClip procedure. We measured peak systolic velocity (Sv), diastolic velocity (Dv), systolic velocity time integral (Svti), diastolic velocity time integral (Dvti), and those systolic to diastolic ratio as PV flow parameters. Systolic PV flow velocity was lower than diastolic PV flow velocity before the procedure, but systolic PV flow velocity markedly increased after the procedure. Peak Sv/Dv ratio and Svti/Dvti ratio after the procedure were significantly higher than those before the procedure (peak Sv/Dv; 1.06 [inter-quartile range (IQR) 0.73 to 1.34] vs 0.32 [IQR 0.03 to 0.55], p <0.001, Svti/Dvti; 1.06 [IQR 0.76 to 1.61] vs 0.26 [IQR 0.02 to 0.51], p <0.001). Peak Sv/Dv ratio and Svti/Dvti ratio were negatively correlated with mean LA pressure and LA pressure V wave, respectively (peak Sv/Dv ratio; r = -0.50 and r = -0.59, Svti/Dvti ratio; r = -0.47 and r = -0.58, p <0.001). In receiver operating characteristics curve assessing the ability of PV flow to predict mean LA pressure ≥20 mm Hg after the successful procedure, the area under the curve of peak Sv/Dv ratio was 0.76 (p <0.001). Peak Sv/Dv ratio <0.98 best predicted LA pressure ≥20 mm Hg with 77% sensitivity and 71% specificity. In conclusion, systolic PV flow velocity immediately increased in response to mitral regurgitation reduction during MitraClip procedure. PV flow velocity, specifically systolic to diastolic ratio, was useful to evaluate invasively determined LA pressure.

Development and Validation of a Nomogram for Predicting the Long-Term Survival in Patients With Chronic Thromboembolic Pulmonary Hypertension

There remains a lack of prognosis models for patients with chronic thromboembolic pulmonary hypertension (CTEPH). This study aims to develop a nomogram predicting 3-, 5-, and 7-year survival in patients with CTEPH and verify the prognostic model. Patients with CTEPH diagnosed in Fuwai Hospital were enrolled consecutively between May 2013 and May 2019. Among them, 70% were randomly split into a training set and the other 30% as a validation set for external validation. Cox proportional hazards model was used to identify the potential survival-related factors which were candidate variables for the establishment of nomogram and the final model was internally validated by the bootstrap method. A total of 350 patients were included in the final analysis and the median follow-up period of the whole cohort was 51.2 months. Multivariate analysis of Cox proportional hazards regression showed body mass index, mean right atrial pressure, N-terminal pro-brain natriuretic peptide (per 500 ng/ml increase in concentration), presence of anemia, and main treatment choice were the independent risk factors of mortality. The nomogram demonstrated good discrimination with the corrected C-index of 0.82 in the training set, and the C-index of 0.80 (95% CI: 0.70 to 0.91) in the external validation set. The calibration plots also showed a good agreement between predicted and actual survival in both training and validation sets. In conclusion, we developed an easy-to-use nomogram with good apparent performance using 5 readily available variables, which may help physicians to identify CTEPH patients at high risk for poor prognosis and implement medical interventions.

Interatrial septal motion as a novel index to predict left atrial pressure

We investigated whether the interatrial septal (IAS) motion of each heartbeat which is observed by transesophageal echocardiography reflects left atrial pressure (LAP) in patients with atrial fibrillation (AF). We studied 100 patients (70 males, age 67 ± 9 years) who underwent catheter ablation for AF. The amplitude of IAS motion was measured using M-mode and averaged for five cardiac cycles. Left and right atrial pressures, the left to right atrial pressure gradient were directly measured during the catheter ablation. In patients with sinus rhythm during measurement, elevated mean LAP, larger maximum left to right atrial pressure gradient, and greater left atrial emptying fraction were associated with IAS motion. The optimal cut-off value of the IAS motion for predicting high LAP (mean LAP > 15 mmHg) was 8.5 mm (sensitivity 100%, specificity 70.1%) in patients with sinus rhythm during pressure measurement. In addition, all patients were divided into 6 groups based on rhythm during measurement and cutoff value of IAS motion. In patients with sinus rhythm during measurement, low IAS motion group had a highest prevalence of elevated LAP compared with high IAS motion group (64 vs. 0%, P < 0.0001). The amplitude of interatrial septal motion during sinus rhythm reflects left atrial pressure in patients with atrial fibrillation. Interatrial septal motion could be a new index to predict elevated left atrial pressure.

Accelerated atrial pacing reduces left-heart filling pressure: a combined clinical-computational study

BACKGROUND AND AIMS

Accelerated atrial pacing offers potential benefits for patients with heart failure with preserved ejection fraction (HFpEF) and atrial fibrillation (AF), compared with standard lower-rate pacing. The study investigates the relationship between atrial pacing rate and left-heart filling pressure.

METHODS

Seventy-five consecutive patients undergoing catheter ablation for AF underwent assessment of mean left atrial pressure (mLAP) and atrioventricular (AV) conduction delay (PR interval) in sinus rhythm and accelerated atrial pacing with 10 bpm increments up to Wenckebach block. Computer simulations (CircAdapt) of a virtual HFpEF cohort complemented clinical observations and hypothesized the modulating effects of AV coupling and atrial (dys)function.

RESULTS

In the study cohort, 49(65%) patients had a high HFpEF likelihood (H2FPEF ≥ 5.0), and 28(37%) an elevated mLAP ≥ 15 mmHg at sinus rhythm. Optimal pacing rates of 100 [70-110]bpm (median [IQR]) significantly reduced mLAP from 12.8 [10.0-17.4]mmHg in sinus rhythm (55 [52-61]bpm) to 10.4 [7.8-14.8]mmHg (P < .001). Conversely, higher pacing rates (130 [110-140]bpm) significantly increased mLAP to 14.7 [11.0-17.8]mmHg (P < .05). PR interval and, hence, AV conduction delay prolonged incrementally with increasing pacing rates. Simulations corroborated these clinical findings, showing mLAP reduction at a moderately increased pacing rate and a subsequent increase at higher rates. Moreover, simulations suggested that mLAP reduction is optimized when AV conduction delay shortens with increasing rate.

CONCLUSIONS

Accelerated pacing acutely reduces left-heart filling pressure in patients undergoing AF catheter ablation and computer simulations with HFpEF features, suggesting it as a potential therapeutic strategy to alleviate congestion symptoms. Virtual HFpEF patient cohorts hypothesize that AV sequential pacing may further optimize this therapy's beneficial effects.

Can the Pulmonary Artery Wedge Pressure be Used Reliably as a Surrogate for the Left Atrial Mean Pressure in Pre-Fontan Evaluation?

The correlation between mean pulmonary artery wedge pressure (PAWP) and left atrial mean pressure (LAMP) has been poorly studied in patients with single ventricle (SV) physiology (Bernstein et al. in Pediatr Cardiol 33: 15-20 2012). The aim of this study is to determine if the PAWP can be used safely as a surrogate to the LAMP to calculate the pulmonary vascular resistance (PVR) during the pre-Fontan evaluation. Also, we aimed to understand if the presence of significant systemic-to-pulmonary collaterals (SPCs) is a confounding factor for accurate estimation of the LAMP. From February 2007 to February 2017, forty-one patients were eligible for inclusion in the study. These patients were varied in terms of underlying cardiac malformation. Sex distribution was equal with 20 males and 21 females. Median weight was 11.8 kg, median body surface area was 0.51 m², median age at catheterization was 2 years, and the median age at Glenn surgery was 5 months. We found the left and right PAWP and LAMP correlated strongly and the differences in the measurements were negligible. Similar findings were observed when calculating PVRs using PAWP and LAMP. These findings were more pronounced in the absence of significant SPCs. PAWP and LAMP correlation was still valid in the presence of significant SPCs; however, the correlation among the calculated PVRs was more attenuated.

Heightened Dependence of Left-Heart Filling Pressures on Right-Heart Failure in Congenital Heart Disease

BACKGROUND

Pulmonary artery wedge pressure (PAWP) is often elevated in patients with right-sided congenital heart disease (CHD), raising the possibility of coexisting left-heart disease, but pressure-volume relationships in the left and right sides of the heart influence one another through interdependence, which may be amplified in patients with CHD.

METHODS

We hypothesized that increases in PAWP in patients with CHD would be more strongly related to ventricular interdependence compared with patients who have isolated left-heart disease such as heart failure with preserved ejection fraction (HFpEF). Ventricular interdependence was assessed by the relationship between PAWP and right-atrial pressure (RAP), RAP/PAWP ratio, and the left-ventricular (LV) eccentricity index.

RESULTS

PAWP was elevated (≥15 mm Hg) in 49% of patients with CHD (n = 449). There was a very strong correlation between RAP and PAWP in CHD (r = 0.81, P < 0.001) that greatly exceeded the respective correlation in HFpEF (n = 160; r = 0.58, P < 0.001; P < 0.001 between groups). RAP/PAWP ratio and LV eccentricity index were higher in CHD than HFpEF (1.26 ± 0.18 vs 1.05 ± 0.14, P = 0.007) and (0.80 ± 0.21 vs 0.59 ± 0.19, P < 0.001), respectively. RAP (but not PAWP) was an independent predictor of death/transplant (hazard ratio 1.86 per 5 mm Hg, 95% confidence interval, 1.39-2.45, P = 0.002).

CONCLUSIONS

Left-heart filling pressures are commonly elevated in right-sided CHD, but this is related predominantly to right-heart failure and enhanced ventricular interdependence rather than left-heart disease. These data provide new insight into the basis of abnormal left-heart hemodynamics in patients with CHD and reinforce the importance of therapeutic interventions targeted to the right heart.

Physician-directed patient self-management in heart failure using left atrial pressure: Interim insights from the VECTOR-HF I and IIa studies

AIMS

Haemodynamic monitoring using implantable pressure sensors reduces the risk of heart failure (HF) hospitalizations. Patient self-management (PSM) of haemodynamics in HF has the potential to personalize treatment, increase adherence, and reduce the risk of worsening HF, while lowering clinicians' burden.

METHODS AND RESULTS

The VECTOR-HF I and IIa studies are prospective, single-arm, open-label clinical trials assessing safety, usability and performance of left atrial pressure (LAP)-guided HF management using PSM in New York Heart Association class II and III HF patients. Physician-prescribed LAP thresholds trigger patient self-adjustment of diuretics. Primary endpoints include the ability to perform LAP measurements and transmit data to the healthcare provider (HCP) interface and the patient guidance application, and safety outcomes. This is an interim analysis of 13 patients using the PSM approach. Over 12 months, no procedure- or device-related major adverse cardiovascular or neurological events were observed, and there were no failures to obtain measurements from the sensor and transmit the data to the HCP interface and the patient guidance application. Patient adherence was 91.4%. Using PSM, annualized HF hospitalization rate significantly decreased compared to a similar period prior to PSM utilization (0 admissions vs. 0.69 admissions over 11.84 months, p = 0.004). At 6 months, 6-min walk test distance and the Kansas City Cardiomyopathy Questionnaire overall summary score demonstrated significant improvement.

CONCLUSIONS

Interim findings suggest that PSM using a LAP monitoring system is feasible and safe. PSM is associated with high patient adherence, potentially improving HF patients' functional status, quality of life, and limiting HF hospitalizations.

Peripheral venous pressure measurements to evaluate congestion in pulmonary arterial hypertension

BACKGROUND

Right atrial pressure (RAP) is an important prognostic criterion in pulmonary hypertension. Elevated mean RAP measured by cardiac catheterization is an independent risk factor for mortality. Accurate bedside assessment of congestion in the management of patients with PH remains challenging. As a continuous conduit of circulating fluid, systemic congestion represented by high RAP may be reflected by peripheral venous pressure (PVP). We evaluated the reliability of PVP measurements for assessing congestion beyond conventional clinical assessments.

METHODS

We performed conventional congestion assessments and PVP measurements in 138 patients undergoing right heart catheterization. PVP was measured via the 16-gauge peripheral venous access placed in the upper extremity.

RESULTS

The mean RAP and PVP were 8.7 ± 4.2 mm Hg and 10.7 ± 4.3 mm Hg, respectively. PVP exhibited a strong linear correlation with RAP (Pearson R = 0.839; P < .001). PVP demonstrated significant discriminatory power for both RAP < 8 mm Hg (area under the curve: 0.91 [95% confidence interval: 0.86 to 0.96]; sensitivity: 72%; specificity: 94% cutoff: 8.5 mm Hg) and RAP ≥ 12 mm Hg (area under the curve: 0.92 [0.87 to 0.97]; sensitivity: 82%; specificity: 89% cutoff: 12.5 mm Hg).

CONCLUSION

PVP measured via peripheral venous access strongly correlates with invasively obtained RAP. PVP measurements may improve current bedside assessments of congestion.