Diastolic ventricular interaction in chronic heart failure

Mechanical Preload Reduction: Harnessing a Cornerstone of Heart Failure Management to Improve Clinical Outcomes

Decongestion is a cornerstone therapeutic goal for those presenting with decompensated heart failure. Current approaches to clinical decongestion include reducing cardiac preload, which is typically limited to diuretics and hemofiltration. Several new technologies designed to mechanically reduce cardiac preload are in development. In this review, we discuss the pathophysiology of decompensated heart failure; the central role of targeting cardiac preload; emerging mechanical preload reduction technologies; and potential application of these devices.

Obesity in Heart Failure with Reduced Ejection Fraction: Time to Address the Elephant in the Room

Obesity has been long recognized as a risk factor for the development of heart failure, but recent evidence suggests obesity is more typically associated with heart failure with preserved ejection fraction as opposed to heart failure with reduced ejection fraction (HFrEF). Nevertheless, numerous studies have found that obesity modulates the presentation and progression of HFrEF and may contribute to the development of HFrEF in some patients. Although obesity has definite negative effects in HFrEF patients, the effects of intentional weight loss in HFrEF patients with obesity have been poorly studied.

Cell to whole organ global sensitivity analysis on a four-chamber heart electromechanics model using Gaussian processes emulators

Cardiac pump function arises from a series of highly orchestrated events across multiple scales. Computational electromechanics can encode these events in physics-constrained models. However, the large number of parameters in these models has made the systematic study of the link between cellular, tissue, and organ scale parameters to whole heart physiology challenging. A patient-specific anatomical heart model, or digital twin, was created. Cellular ionic dynamics and contraction were simulated with the Courtemanche-Land and the ToR-ORd-Land models for the atria and the ventricles, respectively. Whole heart contraction was coupled with the circulatory system, simulated with CircAdapt, while accounting for the effect of the pericardium on cardiac motion. The four-chamber electromechanics framework resulted in 117 parameters of interest. The model was broken into five hierarchical sub-models: tissue electrophysiology, ToR-ORd-Land model, Courtemanche-Land model, passive mechanics and CircAdapt. For each sub-model, we trained Gaussian processes emulators (GPEs) that were then used to perform a global sensitivity analysis (GSA) to retain parameters explaining 90% of the total sensitivity for subsequent analysis. We identified 45 out of 117 parameters that were important for whole heart function. We performed a GSA over these 45 parameters and identified the systemic and pulmonary peripheral resistance as being critical parameters for a wide range of volumetric and hemodynamic cardiac indexes across all four chambers. We have shown that GPEs provide a robust method for mapping between cellular properties and clinical measurements. This could be applied to identify parameters that can be calibrated in patient-specific models or digital twins, and to link cellular function to clinical indexes.

Heart Failure with Preserved Ejection Fraction and Pulmonary Hypertension: Focus on Phosphodiesterase Inhibitors

Pulmonary hypertension (PH) is common in patients with heart failure with preserved ejection fraction (HFpEF). A chronic increase in mean left atrial pressure leads to passive remodeling in pulmonary veins and capillaries and modest PH (isolated postcapillary PH, Ipc-PH) and is not associated with significant right ventricular dysfunction. In approximately 20% of patients with HFpEF, "precapillary" alterations of pulmonary vasculature occur with the development of the combined pre- and post-capillary PH (Cpc-PH), pertaining to a poor prognosis. Current data indicate that pulmonary vasculopathy may be at least partially reversible and thus serves as a therapeutic target in HFpEF. Pulmonary vascular targeted therapies, including phosphodiesterase (PDE) inhibitors, may have a valuable role in the management of patients with PH-HFpEF. In studies of Cpc-PH and HFpEF, PDE type 5 inhibitors were effective in long-term follow-up, decreasing pulmonary artery pressure and improving RV contractility, whereas studies of Ipc-PH did not show any benefit. Randomized trials are essential to elucidate the actual value of PDE inhibition in selected patients with PH-HFpEF, especially in those with invasively confirmed Cpc-PH who are most likely to benefit from such treatment.

Hemodynamics for the Heart Failure Clinician: A State-of-the-Art Review

Heart failure (HF) fundamentally reflects an inability of the heart to provide adequate blood flow to the body without incurring the cost of increased cardiac filling pressures. This failure occurs first during the stressed state, but progresses until hemodynamic derangements become apparent at rest. As such, the measurement and interpretation of both resting and stressed hemodynamics serve an integral role in the practice of the HF clinician. In this review, we discuss conceptual and technical best practices in the performance and interpretation of both resting and invasive exercise hemodynamic catheterization, relate important pathophysiologic concepts to clinical care, and discuss updated, evidence-based applications of hemodynamics as they pertain to the full spectrum of HF conditions.

High Central Venous Pressure and Right Ventricle Size Are Related to Non-decreased Left Ventricle Stroke Volume After Negative Fluid Balance in Critically Ill Patients: A Single Prospective Observational Study

Background: Optimal adjustment of cardiac preload is essential for improving left ventricle stroke volume (LVSV) and tissue perfusion. Changes in LVSV caused by central venous pressure (CVP) are the most important concerns in the treatment of critically ill patients. Objectives: This study aimed to clarify the changes in LVSV after negative fluid balance in patients with elevated CVP, and to elucidate the relationship between the parameters of right ventricle (RV) filling state and LVSV changes. Methods: This prospective cohort study included patients with high central venous pressure (CVP) (≥8 mmHg) within 24 h of ICU admission in the Critical Medicine Department of Peking Union Medical College Hospital. Patients were classified into two groups based on the LVSV changes after negative fluid balance. The cutoff value was 10%. The hemodynamic and echo parameters of the two groups were recorded at baseline and after negative fluid balance. Results: A total of 71 patients included in this study. Forty in VI Group (LVOT VTI increased ≥10%) and 31 in VNI Group (LVOT VTI increased <10%). Of all patients, 56.3% showed increased LVSV after negative fluid balance. In terms of hemodynamic parameters at T0, patients in VI Group had a higher CVP (p < 0.001) and P(v-a)CO₂ (p < 0.001) and lower ScVO₂ (p < 0.001) relative to VNI Group, regarding the echo parameters at T0, the RV_D/LV_D ratio (p < 0.001), DIVC _{end-expiratory} (p < 0.001), and ΔLVOT VTI (p < 0.001) were higher, while T0 LVOT VTI (p < 0.001) was lower, in VI Group patients. The multifactor logistic regression analysis suggested that a high CVP and RV_D/LV_D ratio ≥0.6 were significant associated with LVSV increase after negative fluid balance in critically patients. The AUC of CVP was 0.894. A CVP >10.5 mmHg provided a sensitivity of 87.5% and a specificity of 77.4%. The AUC of CVP combined with the RV_D/LV_D ratio ≥0.6 was 0.926, which provided a sensitivity of 92.6% and a specificity of 80.4%. Conclusion: High CVP and RV_D/LV_D ratio ≥0.6 were significant associated with RV stressed in critically patients. Negative fluid balance will not always lead to a decrease, even an increase, in LVSV in these patients.

Epicardial Fat Expansion in Diabetic and Obese Patients With Heart Failure and Preserved Ejection Fraction-A Specific HFpEF Phenotype

Heart failure with preserved ejection fraction (HFpEF) is a heterogeneous syndrome with diverse etiologies and pathophysiological factors. Obesity and type 2 diabetes mellitus (T2DM), conditions that coexist frequently, induce a cluster of metabolic and non-metabolic signaling derangements which are in favor to induce inflammation, fibrosis, myocyte stiffness, all hallmarks of HFpEF. In contrast to other HFpEF risk factors, obesity and T2DM are often associated with the generation of enlarged epicardial adipose tissue (EAT). EAT acts as an endocrine tissue that may exacerbate myocardial inflammation and fibrosis via various paracrine and vasocrine signals. In addition, an abnormally large EAT poses mechanical stress on the heart via pericardial restrain. HFpEF patients with enlarged EAT may belong to a unique phenotype that can benefit from specific EAT-targeted interventions, including life-style modifications and pharmacologically via statins and fat modifying anti-diabetics drugs; like metformin, sodium-glucose cotransporter 2 inhibitors, or glucagon-like peptide-1 receptor agonists, respectively.

The design and use of a simple device for the MRI assessment of changes in cardiovascular function by lower-body negative-pressure-simulated reduction of central blood volume

AIM

To use a locally designed and simple lower-body negative-pressure (LBNP) device and 1.5 T magnetic resonance imaging (MRI) to demonstrate the ability to assess changes in cardiovascular function during preload reduction. These effects were evaluated on ventricular volumes and great vessel flow in healthy volunteers, for which there are limited published data.

MATERIAL AND METHODS

After ethical review, 14 volunteers (mean age 33.9 ± 7 years, mean body mass index [BMI] 23.1 ± 2.5) underwent LBNP prospectively at 0, -5, -10, and -20 mmHg pressure, using a locally designed LBNP box. Expiratory breath-hold biventricular volumes, and free-breathing flow imaging of the ascending aorta and main pulmonary artery were acquired at each level of LBNP.

RESULTS

At -5 mmHg, there was no change in aortic flow or left ventricular volumes versus baseline. Right ventricular output (p=0.013) and pulmonary net flow (p=0.026) decreased. At -20 mmHg, aortic and pulmonary net flow (p<0.001) decreased, as were left and right ventricular end diastolic volume (p<0.001) and left and right end systolic volumes (p=0.038 and p=0.003 respectively).

CONCLUSIONS

Use of a MRI-compatible LBNP device is feasible to measure changes in ventricular volume and great arterial flow in the same experiment. This may enhance further research into the effects of preload reduction by MRI in a wide range of important cardiovascular pathologies.

Extracardiac Abnormalities of Preload Reserve: Mechanisms Underlying Exercise Limitation in Heart Failure with Preserved Ejection Fraction, Autonomic Dysfunction, and Liver Disease

While many of the cardiac limitations to exercise performance are now well-characterized, extracardiac limitations to exercise performance have been less well recognized but are nevertheless important. We propose that abnormalities of cardiac preload reserve represents an under-recognized but common cause of exercise limitations. We further propose that mechanistic links exist between conditions as seemingly disparate as heart failure with preserved ejection fraction, nonalcoholic fatty liver disease, and pelvic venous compression/obstruction syndromes (eg, May-Thurner). We conclude that extracardiac abnormalities of preload reserve serve as a major pathophysiologic mechanism underlying these and other disease states.

Acute Unloading Effects of Sildenafil Enhance Right Ventricular-Pulmonary Artery Coupling in Heart Failure

BACKGROUND

Phosphodiesterase-5A inhibitors (PDE5i) are sometimes used in patients with advanced heart failure with reduced ejection fraction before heart transplant or left ventricular assist device implantation to decrease right ventricular (RV) afterload and mitigate the risk of right heart failure. Conflicting evidence exists regarding the impact of these drugs on RV contractility. The aim of this study was to explore the acute effects of PDE5i on ventricular-vascular coupling and load-independent RV contractility.

METHODS

Twenty-two patients underwent right heart catheterization and gated equilibrium blood pool single photon emission computed tomography, before and after 20 mg intravenous sildenafil. Single photon emission computed tomography and right heart catheterization-derived data were used to calculate RV loading and contractility.

RESULTS

PDE5i induced a decrease in the right atrial pressure (-43%), pulmonary artery (PA) mean pressure (-26%), and PA wedge pressure (PAWP; -23%), with favorable reductions in pulmonary vascular resistance (-41%) and PA elastance (-40%), and increased cardiac output (+13%) (all P < 0.01). The RV ejection fraction increased with sildenafil (+20%), with no change of RV contractility (P = 0.74), indicating that the improvement in the RV ejection fraction was related to enhanced RV-PA coupling (r = 0.59, P = 0.004) by a decrease in the ventricular load. RV diastolic compliance increased with sildenafil. The decrease in the PAWP correlated with RV end-diastolic volume decrease; no relationship was observed with the change in LV transmural pressure, suggesting decreased pericardial constraint.

CONCLUSIONS

Acute PDE5i administration has profound RV afterload-reducing effects, improves the RVEF, decreases RV volumes, and decreases the PAWP, predominantly through relief of pericardial constraint, without effects on RV chamber contractility. These findings support further study of PDE5i in protection of RV function in advanced heart failure with reduced ejection fraction who are at risk of RV failure.

The Role of the Pericardium in Heart Failure: Implications for Pathophysiology and Treatment

The elastic pericardium exerts a compressive contact force on the surface of the myocardium that becomes more substantial when heart volume increases, as in patients with various forms of heart failure (HF). Pericardial restraint plays an important role in determining hemodynamics and ventricular function in both health and disease. This review discusses the physiology of pericardial restraint in HF and explores the question of whether it can be targeted indirectly through medical interventions or directly through a number of existing and future therapies.

Understanding preload and preload reserve within the conceptual framework of a limited range of possible left ventricular end-diastolic volumes

Preload has been variously defined, but if there is to be a direct relationship with activity of the Frank-Starling mechanism in its action to increase the force and extent of contraction, preload must directly reflect myocardial stretch. The Frank-Starling mechanism is activated during any stretch of a cardiac chamber beyond its resting size, which is present immediately before contraction. Every left ventricle has an intrinsic and limited range of possible volumes at end diastole. There is a curvilinear relationship between left ventricular (LV) end-diastolic pressure (LVEDP) and LV end-diastolic volume (LVEDV), and, at maximal or near maximal LVEDV, there will be a high LVEDP. Within the possible range, the LVEDV will be determined by the extent of filling, any change in LVEDV will result in changed activity of the Frank-Starling mechanism, and change in LVEDV might, therefore, be considered to represent change in preload. On the other hand, it is the difference between the current and the maximal possible LVEDV (or the preload reserve) that may be of the most clinical relevance. There is a reciprocal relationship between preload and preload reserve, with minor or absent LV preload reserve indicating that there will be either minimal or no increase in stroke volume following intravenous fluid administration. As left atrial pressure can remain within the normal range when the LVEDP is elevated, it is LVEDP, and not left atrial pressure, that provides the most reliable guide to preload reserve in an individual at a specific period in time.

Diastolic Ventricular Interaction in Heart Failure With Preserved Ejection Fraction

Background

Exercise‐induced pulmonary hypertension is common in heart failure with preserved ejection fraction (HFpEF). We hypothesized that this could result in pericardial constraint and diastolic ventricular interaction in some patients during exercise.

Methods and Results

Contrast stress echocardiography was performed in 30 HFpEF patients, 17 hypertensive controls, and 17 normotensive controls (healthy). Cardiac volumes, and normalized radius of curvature (NRC) of the interventricular septum at end‐diastole and end‐systole, were measured at rest and peak‐exercise, and compared between the groups. The septum was circular at rest in all 3 groups at end‐diastole. At peak‐exercise, end‐systolic NRC increased to 1.47±0.05 (P<0.001) in HFpEF patients, confirming development of pulmonary hypertension. End‐diastolic NRC also increased to 1.54±0.07 (P<0.001) in HFpEF patients, indicating septal flattening, and this correlated significantly with end‐systolic NRC (ρ=0.51, P=0.007). In hypertensive controls and healthy controls, peak‐exercise end‐systolic NRC increased, but this was significantly less than observed in HFpEF patients (HFpEF, P=0.02 versus hypertensive controls; P<0.001 versus healthy). There were also small, non‐significant increases in end‐diastolic NRC in both groups (hypertensive controls, +0.17±0.05, P=0.38; healthy, +0.06±0.03, P=0.93). In HFpEF patients, peak‐exercise end‐diastolic NRC also negatively correlated (r=−0.40, P<0.05) with the change in left ventricular end‐diastolic volume with exercise (ie, the Frank‐Starling mechanism), and a trend was noted towards a negative correlation with change in stroke volume (r=−0.36, P=0.08).

Conclusions

Exercise pulmonary hypertension causes substantial diastolic ventricular interaction on exercise in some patients with HFpEF, and this restriction to left ventricular filling by the right ventricle exacerbates the pre‐existing impaired Frank‐Starling response in these patients.

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.

Biventricular pacemaker therapy improves exercise capacity in patients with non-obstructive hypertrophic cardiomyopathy via augmented diastolic filling on exercise

AIMS

Treatment options for patients with non-obstructive hypertrophic cardiomyopathy (HCM) are limited. We sought to determine whether biventricular (BiV) pacing improves exercise capacity in HCM patients, and whether this is via augmented diastolic filling.

METHODS AND RESULTS

Thirty-one patients with symptomatic non-obstructive HCM were enrolled. Following device implantation, patients underwent detailed assessment of exercise diastolic filling using radionuclide ventriculography in BiV and sham pacing modes. Patients then entered an 8-month crossover study of BiV and sham pacing in random order, to assess the effect on exercise capacity [peak oxygen consumption (VO₂ )]. Patients were grouped on pre-specified analysis according to whether left ventricular end-diastolic volume increased (+LVEDV) or was unchanged/decreased (-LVEDV) with exercise at baseline. Twenty-nine patients (20 male, mean age 55 years) completed the study. There were 14 +LVEDV patients and 15 -LVEDV patients. Baseline peak VO₂ was lower in -LVEDV patients vs. +LVEDV patients (16.2 ± 0.9 vs. 19.9 ± 1.1 mL/kg/min, P = 0.04). BiV pacing significantly increased exercise ΔLVEDV (P = 0.004) and Δstroke volume (P = 0.008) in -LVEDV patients, but not in +LVEDV patients. Left ventricular ejection fraction and end-systolic elastance did not increase with BiV pacing in either group. This translated into significantly greater improvements in exercise capacity (peak VO₂  + 1.4 mL/kg/min, P = 0.03) and quality of life scores (P = 0.02) in -LVEDV patients during the crossover study. There was no effect on left ventricular mechanical dyssynchrony in either group.

CONCLUSION

Symptomatic patients with non-obstructive HCM may benefit from BiV pacing via augmentation of diastolic filling on exercise rather than contractile improvement. This may be due to relief of diastolic ventricular interaction.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.gov NCT00504647.

Diastolic Dysfunction and Heart Failure With Preserved Ejection Fraction: Understanding Mechanisms by Using Noninvasive Methods

Research in the last decade has substantially advanced our understanding of the pathophysiology of heart failure with preserved ejection fraction (HFpEF). However, treatment options remain limited as clinical trials have largely failed to identify effective therapies. Part of this failure may be related to mechanistic heterogeneity. It is speculated that categorizing HFpEF patients based upon underlying pathophysiological phenotypes may represent the key next step in delivering the right therapies to the right patients. Echocardiography may provide valuable insight into both the pathophysiology and underlying phenotypes in HFpEF. Echocardiography also plays a key role in the evaluation of patients with unexplained dyspnea, where HFpEF is suspected but the diagnosis remains unknown. The combination of the E/e' ratio and right ventricular systolic pressure has recently been shown to add independent value to the diagnostic evaluation of patients suspected of having HFpEF. Finally, echocardiography enables identification of the different causes that mimic HFpEF but are treated differently, such as valvular heart disease, pericardial constriction, and high-output heart failure or infiltrative myopathies such as cardiac amyloid. This review summarizes the current understanding of the pathophysiology and phenotyping of HFpEF with particular attention to the role of echocardiography in this context.

Adverse Renal Response to Decongestion in the Obese Phenotype of Heart Failure With Preserved Ejection Fraction

BACKGROUND

Patients with heart failure (HF) with preserved ejection fraction (HFpEF) and obesity display a number of pathophysiologic features that may render them more or less vulnerable to negative effects of decongestion on renal function, including greater right ventricular remodeling, plasma volume expansion and pericardial restraint. We aimed to contrast the renal response to decongestion in obese compared to nonobese patients with HFpEF METHODS AND RESULTS: National Institutes of Health heart failure network studies that enrolled patients with acute decompensated HFpEF (EF ≥ 50%) were included (DOSE, CARRESS, ROSE, and ATHENA). Obese HFpEF was defined as a body mass index ≥ 30 kg/m². Compared to nonobese HFpEF (n = 118), patients with obese HFpEF (n = 214) were an average of 9 years younger (71 vs 80 years,< 0.001), were more likely to have diabetes (64% vs 31%, P< 0.001) but had less atrial fibrillation (56% vs 75%, P< 0.001). Renal dysfunction (glomerular filtration rate < 60 mL/min/1.73m²) was present in 82% of patients, and there was no difference at baseline between obese and nonobese patients. Despite similar weight loss through decongestive therapies, obese patients with HFpEF demonstrated greater rise in creatinine (Cr) and decline in glomerular filtration rate, with a 2-fold higher incidence of mild worsening renal function (rise in Cr ≥ 0.3 mg/dL) (28 vs 14%, P = 0.008) and a substantially greater increase in severe worsening of renal function (rise in Cr > 0.5 mg/dL) (9 vs 0%, P = 0.002).

CONCLUSIONS

Despite being nearly a decade younger, obese patients with HFpEF experience greater deterioration in renal function during decongestion than do nonobese patients with HFpEF. Further study to elucidate the complex relationships between volume distribution, cardiorenal hemodynamics and adiposity in HFpEF is needed.

[Mechanisms of exercise intolerance in patients with heart failure and preserved ejection fraction. Part II: The role of right heart chambers, vascular system and skeletal muscles]

The main clinical manifestation of heart failure with preserved ejection fraction is poor exercise tolerance. In addi-tion to the dysfunction of the left heart chambers, which were presented in the first part of this review, many other disorders are involved in poor exercise tolerance in such patients: impairments of the right heart, vascular system and skeletal muscle. The second part of this review presents the mechanisms for the development of these disorders, as well as possible ways to correct them.

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

BACKGROUND

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.

METHODS AND RESULTS

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.

CONCLUSION

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.

Ventricular interaction in the jugular venous pulse in aortic regurgitation

A patient with severe aortic regurgitation due to rapidly progressive staphylococcal endocarditis demonstrated an unusual physical sign of prominent diastolic venous pulsation. We suggest that this venous pulse is the result of diastolic ventricular interaction in which inflow of blood into the right ventricle is arrested in the latter part of diastole due to extreme left ventricular distension. We wish to highlight this sign so that others can look for it with the aim of improving our understanding and treatment of ventricular interaction associated with heart failure.

Diastolic dyssynchrony and its exercise-induced changes affect exercise capacity in patients with heart failure with reduced ejection fraction

BACKGROUND

Left ventricular diastolic dyssynchrony is common in patients with heart failure with reduced ejection fraction (HFREF). Little is known however, about its pathophysiology and clinical effects. Herein is hypothesized that presence of diastolic dyssynchrony at rest or at exercise may importantly contribute to HF symptoms. The aim was to investigate the influence of diastolic dyssynchrony and its exercise-induced changes on exercise capacity in HFREF patients.

METHODS

Patients with stable, chronic HF, left ventricular ejection fraction < 35%, sinus rhythm and QRS ≥ 120 ms were eligible for the study. Rest and cyclo-ergometer exercise echocardiography were performed. Diastolic dyssynchrony was defined as opposing-wall-diastolic-delay ≥ 55 ms measured in tissue-Doppler imaging. Exercise capacity was assessed by peak oxygen consumption (VO2peak). Association between diastolic dyssynchrony and VO2peak was assessed in univariate regression analysis and further adjusted for possible confounders.

RESULTS

Fourty eight patients were included (aged 63.7 ± 12.2). Twenty-seven (56.25%) had diastolic dyssynchrony at rest and 13 (27%) at exercise. Twenty-two (46%) experienced a change in diastolic dyssynchrony status during exercise. In univariate models diastolic dyssynchrony at rest or at exercise were associated with lower VO2peak (beta coefficient = -3.8, p = 0.004; beta coefficient = -3.6, p = 0.02, respectively). However, the ability to restore diastolic synchronicity during exercise was associated with higher VO2peak (beta coefficient = 3.4, p = 0.04) and remained an important predictor of exercise capacity after adjustment for age and HF etiology.

CONCLUSIONS

The ability to restore diastolic synchronicity at exercise predicts exercise capacity in patients with HFREF.

C-Type Natriuretic Peptide Ameliorates Lipopolysaccharide-Induced Cardiac Dysfunction in Rats with Pulmonary Arterial Hypertension

Lipopolysaccharide induces rapid deterioration of cardiac function in rats with pulmonary arterial hypertension. It was desired to investigate if this cardiac dysfunction could be treated by C-type natriuretic peptide. Rat pulmonary arterial hypertension was induced by intraperitoneal injection of monocrotaline. Hemodynamics and cardiac function were measured by pressure-volume (P-V) catheter before and after the rats were treated with lipopolysaccharide and C-type natriuretic peptide. Cyclic guanosine 3',5'-monophosphate (cGMP) level was determined by enzyme-linked immunosorbent assay analysis. After the rats were injected with low-dose lipopolysaccharide, they experienced left ventricle systolic function deterioration. Administration of C-type natriuretic peptide improved hemodynamics and left ventricle systolic function. cGMP level was elevated after C-type natriuretic peptide treatment. C-type natriuretic peptide could ameliorate lipopolysaccharide-induced cardiac dysfunction and restore hemodynamic deterioration in rats with pulmonary arterial hypertension.

Echocardiographic predictors of change in renal function with intravenous diuresis for decompensated heart failure

Aims

The aim of this study was to identify echocardiographic predictors of improved or worsening renal function during intravenous diuresis for decompensated heart failure. Secondary aim included defining the incidence and clinical risk factors for acute changes in renal function with decongestion.

Methods and results

A retrospective review of 363 patients admitted to a single centre for decompensated heart failure who underwent intravenous diuresis and transthoracic echocardiography was conducted. Clinical, echocardiographic, and renal function data were retrospectively collected. A multinomial logistic regression model was created to determine relative risk ratios for improved renal function (IRF) or worsening renal function (WRF). Within this cohort, 36% of patients experienced WRF, 35% had stable renal function, and 29% had IRF. Patients with WRF were more likely to have a preserved left ventricular ejection fraction compared with those with stable renal function or IRF (P = 0.02). Patients with IRF were more likely to have a dilated, hypokinetic right ventricle compared with those with stable renal function or WRF (P ≤ 0.01), although this was not significant after adjustment for baseline characteristics. Left atrial size, left ventricular linear dimensions, and diastolic function did not significantly predict change in renal function.

Conclusions

An acute change in renal function occurred in 65% of patients admitted with decompensated heart failure. WRF was statistically more likely in patients with a preserved left ventricular ejection fraction. A trend towards IRF was noted in patients with global right ventricular dysfunction.

Exercise and the right ventricle: a potential Achilles' heel

Exercise is associated with unequivocal health benefits and results in many structural and functional changes of the myocardium that enhance performance and prevent heart failure. However, intense exercise also presents a significant hemodynamic challenge in which the right-sided heart chambers are exposed to a disproportionate increase in afterload and wall stress that can manifest as myocardial fatigue or even damage if intense exercise is sustained for prolonged periods. This review focuses on the physiological factors that result in a disproportionate load on the right ventricle during exercise and the long-term consequences. The changes in cardiac structure and function that define 'athlete's heart' disproportionately affect the right-sided heart chambers and this can raise important diagnostic overlap with some cardiac pathologies, particularly some inherited cardiomyopathies. The interaction between exercise and arrhythmogenic right ventricular cardiomyopathy (ARVC) will be highlighted as an important example of how hemodynamic stressors can combine with deficiencies in cardiac structural elements to cause cardiac dysfunction predisposing to arrhythmias. The extent to which extreme exercise can cause adverse remodelling in the absence of a genetic predisposition remains controversial. In the athlete with profound changes in heart structure, it can be extremely challenging to determine whether common symptoms such as palpitations may be a marker of more sinister arrhythmias. This review discusses some of the techniques that have recently been proposed to identify pathology in these circumstances. Finally, we will discuss recent evidence defining the role of exercise restriction as a therapeutic intervention in individuals predisposed to arrhythmogenic cardiomyopathy.

Mismatch between right- and left-sided filling pressures in heart failure patients with preserved ejection fraction

BACKGROUND

Mismatch between right- and left-sided filling pressures is poorly understood in heart failure with preserved ejection fraction (HFpEF).

METHODS AND RESULTS

We retrospectively analyzed 170 patients with HFpEF (EF≥40%) who underwent right heart catheterization. Low match (right atrial pressure [RAP] < 10 mm Hg and pulmonary capillary wedge pressure [PCWP] < 22 mm Hg) was 76%, high match (RAP ≥ 10 mm Hg and PCWP ≥ 22 mm Hg) was 6.5%, high-R mismatch (RAP ≥ 10 mm Hg and PCWP < 22 mm Hg) was 12%, and high-L mismatch (RAP < 10 mm Hg and PCWP ≥ 22 mm Hg) was 5.9%. Elevated PCWP was a significant predictor of the composite endpoint of death or HF hospitalization within 12months (hazard ratio 5.40, 95% confidence interval 2.17-12.5, p<0.001). Elevated RAP was not significantly associated with worse outcomes. Pulmonary artery systolic pressure (PASP) and diastolic pressure (PADP) showed strong correlations with PCWP (PASP, r=0.738, p<0.001; PADP, r=0.834, p<0.001; RAP, r=0.638, p<0.001, respectively).

CONCLUSIONS

Discordance exists between right- and left-sided filling pressures in HFpEF. Physicians may utilize pulmonary artery pressure to evaluate left-sided filling pressure, which is a significant predictor of prognosis.

Soluble ST2 correlates with some indicators of right ventricular function in hypertensive heart failure

Purpose

ST2 receptor, which is a member of the Toll-like/interleukin-1 (IL-1) receptor family, has been found to be increased in the serum of patients 1 day after myocardial infarction. Several other studies have shown that soluble ST2 levels correlate with severity of heart failure (HF), left ventricular ejection fraction, creatinine clearance, B-type natriuretic peptide and C-reactive protein, and are predictors of mortality in HF. Most of these studies were not only limited to ischemic heart disease but also concentrated on left-sided HF. We therefore decided to study the relationship between soluble ST2 and some markers of right ventricular (RV) function in a cohort of hypertensive HF subjects.

Patients and methods

This is a prospective cohort study of hypertensive HF patients presenting to the University of Abuja Teaching Hospital, Abuja, over a 12-month period. ST2 was measured in plasma sample by the enzyme-linked immunosorbent assay (ELISA) method. Right ventricular diameters in diastole (RVDD) and right atrial area (RAA) were obtained on echocardiography, while right ventricular systolic pressure (RVSP) was estimated from echocardiography by the addition of the pressure gradient between the right ventricle and right atrium (RA) to the pressure in the RA.

Results

There was a significant correlation between RVSP and soluble ST2 (t=0.75, p<0.0001), RVDD (t=0.28, p=0.004) and RAA (t=0.46, p=0.002).

Conclusion

In a cohort of hypertensive HF subjects, soluble ST2 correlates significantly with RVSP, RVDD and RAA.

Cardiac metabolism - A promising therapeutic target for heart failure

Both heart failure with reduced ejection fraction (HFrEF) and with preserved ejection fraction (HFpEF) are associated with high morbidity and mortality. Although many established pharmacological interventions exist for HFrEF, hospitalization and death rates remain high, and for those with HFpEF (approximately half of all heart failure patients), there are no effective therapies. Recently, the role of impaired cardiac energetic status in heart failure has gained increasing recognition with the identification of reduced capacity for both fatty acid and carbohydrate oxidation, impaired function of the electron transport chain, reduced capacity to transfer ATP to the cytosol, and inefficient utilization of the energy produced. These nodes in the genesis of cardiac energetic impairment provide potential therapeutic targets, and there is promising data from recent experimental and early-phase clinical studies evaluating modulators such as carnitine palmitoyltransferase 1 inhibitors, partial fatty acid oxidation inhibitors and mitochondrial-targeted antioxidants. Metabolic modulation may provide significant symptomatic and prognostic benefit for patients suffering from heart failure above and beyond guideline-directed therapy, but further clinical trials are needed.

Left Ventricular Diastolic Function Assessment of a Heterogeneous Cohort of Pulmonary Arterial Hypertension Patients

BACKGROUND

Pulmonary arterial hypertension (PAH) is known to trigger right ventricular (RV) remodeling that might compromise left ventricular (LV) filling due to inter-ventricular interdependence. In this study, we aimed to examine standard echocardiographic measurements of LV diastolic function in PAH patients.

METHODS

In this retrospective study, we identified clinical as well as complete echocardiographic data from 128 chronic PAH patients to fully assess LV diastolic dysfunction (LVDD) using standard recommended Doppler guidelines. Accordingly, patients were divided into three groups: LVDD 0, LVDD 1 and LVDD 2.

RESULTS

The mean age of the studied population was 57 ± 14 years with a mean pulmonary artery systolic pressure (PASP) of 55 ± 21 mm Hg. A total of 36% of the study patients had normal LV diastolic function. However, 64% had LVDD with LVDD stage 1 being the most common (48%). In terms of echocardiographic data, significant differences were found among the three LVDD groups in regards to PASP, LV end systolic and diastolic volumes, tricuspid annular plane systolic excursion, right ventricular fractional area change as well as many other tissue Doppler imaging parameters. Finally, just age and PASP were predictors of abnormal LV diastolic function (P < 0.05).

CONCLUSIONS

Impaired relaxation is a common abnormality in PAH patients. Additional studies are warranted to determine whether LVDD alters prognosis or is related to changes in the symptomatic profile of this group of patients.

Right heart imaging in patients with heart failure: a tale of two ventricles

PURPOSE OF REVIEW

The purpose is to describe the recent advances made in imaging of the right heart, including deformation imaging, tissue, and flow characterization by MRI, and molecular imaging.

RECENT FINDINGS

Recent developments have been made in the field of deformation imaging of the right heart, which may improve risk stratification of patients with heart failure and pulmonary hypertension. In addition, more attention has been given to load adaptability metrics of the right heart; these simplified indices, however, still face challenges from a conceptual point of view. The emergence of novel MRI sequences, such as native T1 mapping, allows better detection and quantification of myocardial fibrosis and could allow better prediction of postsurgical recovery of the right heart. Other advances in MRI include four-dimensional flow imaging, which may be particularly useful in congenital heart disease or for the detection of early stages of pulmonary vascular disease.

SUMMARY

The review will place the recent developments in right heart imaging in the context of clinical care and research.

Right Ventricular Systolic Dysfunction Is Common in Hypertensive Heart Failure: A Prospective Study in Sub-Saharan Africa

INTRODUCTION

Right ventricular (RV) systolic dysfunction is now recognized widely as a strong and independent predictor of adverse outcomes in patients with heart failure (HF). Reduction of RV systolic function more closely predicts impaired exercise tolerance and poor survival than does left ventricular (LV) systolic function. In spite of this, there is a dearth of data on RV function in hypertensive HF which is the commonest form of HF in sub-Saharan Africa. We therefore conducted a prospective cohort study of hypertensive HF patients presenting to the University of Abuja Teaching Hospital, Abuja, Nigeria over an 8 year period.

METHODS

Each subject had transthoracic echocardiography performed on them according to the guidelines of American Society of Echocardiography. RV systolic function was defined as a tricuspid annular plane systolic excursion (TAPSE) <15 mm using M-mode echocardiography.

RESULTS

RV systolic dysfunction was identified in 272 (44.5%) of the 611 subjects that were studied. Subjects with TAPSE less than 15 mm had worse prognosis compared to those with TAPSE ≥15 mm.There was a significant correlation between TAPSE and other adverse prognostic markers including left and right atrial area, LV size, LV mass, LV ejection fraction, restrictive mitral inflow and RV systolic pressure (RVSP). However, LV ejection fraction and right atrial area were the only independent determinants of RV systolic dysfunction.

CONCLUSIONS

Hypertensive HF is a major cause of RV systolic dysfunction even in a population with a low prevalence of coronary artery disease, and RV systolic dysfunction is associated with poor prognosis in hypertensive HF. Detailed assessment of RV function should therefore be part of the echocardiography evaluation of patients with hypertensive HF.

Restrictive right ventricular performance assessed by cardiac magnetic resonance after balloon valvuloplasty of critical pulmonary valve stenosis

BACKGROUND

Little data are published about right ventricular diastolic performance in patients with critical pulmonary valve stenosis after balloon pulmonary valvuloplasty thus far.

METHODS

A total of 44 patients with isolated critical pulmonary valve stenosis who had undergone balloon valvuloplasty with haemodynamic recordings were enrolled to the study; 33 patients who came for follow-up underwent further imaging by echocardiography after 6 months and their right ventricular functional parameters were compared with 33 control patients of the same age and sex. Out of 33 patients, 21 underwent cardiac MRI with late gadolinium enhancement to assess the presence of right ventricular fibrosis.

RESULTS

The right ventricular systolic pressure (p<0.0001) and right ventricular outflow tract gradient (p<0.0001) decreased acutely (p<0.0001) after balloon valvuloplasty. During follow-up, M-mode left ventricular end diastolic dimension (p<0.001) and end systolic dimension increased (p<0.001), whereas right ventricular end diastolic dimension decreased (p<0.001). Compared with controls, patients (n=33) had significantly reduced tricuspid annular Ea and higher E/Ea (p<0.001). Right ventricular systolic dysfunction was also suggested by reduced tricuspid annular systolic velocity (p<0.001). Late gadolinium enhancement was demonstrated in 13 out of 21 patients with restrictive physiology, which involves the anterior right ventricular outflow tract, anterior wall, and inferior wall. The right ventricular late gadolinium enhancement score correlated positively with age (r=0.7, p<0.001) and right ventricular mass index (r=0.52, p<0.001).

CONCLUSION

The persistence of right ventricular diastolic dysfunction after relief of chronic pressure overload of critical pulmonary valve stenosis suggests that a factor - other than increase in afterload - is involved in this physiology. Fibrosis is the most likely factor responsible for persistence of restrictive physiology as documented by late gadolinium enhancement.

Effects of nitrite infusion on skeletal muscle vascular control during exercise in rats with chronic heart failure

Chronic heart failure (CHF) reduces nitric oxide (NO) bioavailability and impairs skeletal muscle vascular control during exercise. Reduction of NO2 (-) to NO may impact exercise-induced hyperemia, particularly in muscles with pathologically reduced O2 delivery. We tested the hypothesis that NO2 (-) infusion would increase exercising skeletal muscle blood flow (BF) and vascular conductance (VC) in CHF rats with a preferential effect in muscles composed primarily of type IIb + IId/x fibers. CHF (coronary artery ligation) was induced in adult male Sprague-Dawley rats. After a >21-day recovery, mean arterial pressure (MAP; carotid artery catheter) and skeletal muscle BF (radiolabeled microspheres) were measured during treadmill exercise (20 m/min, 5% incline) with and without NO2 (-) infusion. The myocardial infarct size (35 ± 3%) indicated moderate CHF. NO2 (-) infusion increased total hindlimb skeletal muscle VC (CHF: 0.85 ± 0.09 ml·min(-1)·100 g(-1)·mmHg(-1) and CHF + NO2 (-): 0.93 ± 0.09 ml·min(-1)·100 g(-1)·mmHg(-1), P < 0.05) without changing MAP (CHF: 123 ± 4 mmHg and CHF + NO2 (-): 120 ± 4 mmHg, P = 0.17). Total hindlimb skeletal muscle BF was not significantly different (CHF: 102 ± 7 and CHF + NO2 (-): 109 ± 7 ml·min(-1)·100 g(-1) ml·min(-1)·100 g(-1), P > 0.05). BF increased in 6 (∼21%) and VC in 8 (∼29%) of the 28 individual muscles and muscle parts. Muscles and muscle portions exhibiting greater BF and VC after NO2 (-) infusion comprised ≥63% type IIb + IId/x muscle fibers. These data demonstrate that NO2 (-) infusion can augment skeletal muscle vascular control during exercise in CHF rats. Given the targeted effects shown herein, a NO2 (-)-based therapy may provide an attractive "needs-based" approach for treatment of the vascular dysfunction in CHF.

Pulmonary Hypertension an Independent Risk Factor for Death in Intensive Care Unit: Correlation of Hemodynamic Factors with Mortality

OBJECTIVE

Critically ill patients with pulmonary hypertension (PH) pose additional challenges due to the existence of right ventricular (RV) dysfunction. The purpose of this study was to assess the impact of hemodynamic factors on the outcome.

METHODS

We reviewed the records of patients with a diagnosis of PH admitted to the intensive care unit. In addition to evaluating traditional hemodynamic parameters, we defined severe PH as right atrial pressure >20 mmHg, mean pulmonary artery pressure >55 mmHg, or cardiac index (CI) <2 L/min/m². We also defined the RV functional index (RFI) as pulmonary artery systolic pressure (PASP) adjusted for CI as PASP/CI; increasing values reflect RV dysfunction.

RESULTS

Fifty-three patients (mean age 60 years, 72% women, 79% Blacks), were included in the study. Severe PH was present in 68% of patients who had higher Sequential Organ Failure Assessment (SOFA) score (6.8 ± 3.3 vs 3.8 ± 1.6; P = 0.001) and overall in-hospital mortality (36% vs 6%; P = 0.02) compared to nonsevere patients, although Acute Physiology and Chronic Health Evaluation (APACHE) II scores (19.9 ± 7.5 vs 18.5 ± 6.04; P = 0.52) were similar and sepsis was more frequent among nonsevere PH patients (31 vs 64%; P = 0.02). Severe PH (P = 0.04), lower mean arterial pressure (P = 0.04), and CI (P = 0.01); need for invasive ventilation (P = 0.02) and vasopressors (P = 0.03); and higher SOFA (P = 0.001), APACHE II (P = 0.03), pulmonary vascular resistance index (PVRI) (P = 0.01), and RFI (P = 0.004) were associated with increased mortality. In a multivariate model, SOFA [OR = 1.45, 95% confidence interval (C.I.) = 1.09–1.93; P = 0.01], PVRI (OR = 1.12, 95% C.I. = 1.02–1.24; P = 0.02), and increasing RFI (OR = 1.06, 95% C.I. = 1.01–1.11; P = 0.01) were independently associated with mortality.

CONCLUSION

PH is an independent risk factor for mortality in critically ill patients. Composite factors rather than individual hemodynamic parameters are better predictors of outcome. Monitoring of RV function using composite hemodynamic factors resulting in specific interventions is likely to improve survival and needs to be studied further.

A disproportionate elevation in right ventricular filling pressure, in relation to left ventricular filling pressure, is associated with renal impairment and increased mortality in advanced decompensated heart failure

BACKGROUND

Discordance between left- and right-sided filling pressures occurs in a subset of patients presenting with acute decompensated heart failure (ADHF). We hypothesized that a disproportionately increased right atrial pressure (RAP) relative to the pulmonary capillary wedge pressure (PCWP) would be associated with both renal dysfunction and mortality in ADHF.

METHODS

A total of 367 patients admitted with ADHF with elevated intracardiac filling pressures were treated with intensive medical therapy guided by invasive hemodynamic monitoring. Baseline characteristics, hemodynamics, and renal function at admission were stratified by RAP/PCWP quartiles. The association of RAP/PCWP quartile with all-cause mortality after a median follow-up of 2.4 years was assessed in univariable and multivariable models, which included adjustment for the RAP.

RESULTS

The median RAP/PCWP was 0.58 (interquartile range 0.43-0.75). Increasing RAP/PCWP was inversely associated with estimated glomerular filtration rate at baseline and with treatment (P < .0001) independently of RAP. High RAP/PCWP was associated with increased mortality (quartile 4 vs 1: hazard ratio [95% CI] 2.1 [1.3-3.5], P = .002). The association of RAP/PCWP with mortality persisted after adjustment for age, gender, mean arterial pressure, RAP, cardiac index, pulmonary vascular resistance, and estimated glomerular filtration rate (hazard ratio 2.4 [1.4-3.9], P = .007).

CONCLUSION

A disproportionate increase in right to left ventricular filling pressures is associated with renal dysfunction and mortality, independently of the right atrial pressure.

Short-term intravenous sodium nitrite infusion improves cardiac and pulmonary hemodynamics in heart failure patients

BACKGROUND

Nitrite exhibits hypoxia-dependent vasodilator properties, selectively dilating capacitance vessels in healthy subjects. Unlike organic nitrates, it seems not to be subject to the development of tolerance. Currently, therapeutic options for decompensated heart failure (HF) are limited. We hypothesized that by preferentially dilating systemic capacitance and pulmonary resistance vessels although only marginally dilating resistance vessels, sodium nitrite (NaNO2) infusion would increase cardiac output but reduce systemic arterial blood pressure only modestly. We therefore undertook a first-in-human HF proof of concept/safety study, evaluating the hemodynamic effects of short-term NaNO2 infusion.

METHODS AND RESULTS

Twenty-five patients with severe chronic HF were recruited. Eight received short-term (5 minutes) intravenous NaNO2 at 10 μg/kg/min and 17 received 50 μg/kg/min with measurement of cardiac hemodynamics. During infusion of 50 μg/kg/min, left ventricular stroke volume increased (from 43.22±21.5 to 51.84±23.6 mL; P=0.003), with marked falls in pulmonary vascular resistance (by 29%; P=0.03) and right atrial pressure (by 40%; P=0.007), but with only modest falls in mean arterial blood pressure (by 4 mm Hg; P=0.004). The increase in stroke volume correlated with the increase in estimated trans-septal gradient (=pulmonary capillary wedge pressure-right atrial pressure; r=0.67; P=0.003), suggesting relief of diastolic ventricular interaction as a contributory mechanism. Directionally similar effects were observed for the above hemodynamic parameters with 10 μg/kg/min; this was significant only for stroke volume, not for other parameters.

CONCLUSIONS

This first-in-human HF efficacy/safety study demonstrates an attractive profile during short-term systemic NaNO2 infusion that may be beneficial in decompensated HF and warrants further evaluation with longer infusion regimens.

Heart rate-dependent left ventricular diastolic function in patients with and without heart failure

BACKGROUND

Chronic heart rate (HR) reduction in the treatment of heart failure (HF) with systolic dysfunction is beneficial, but the immediate mechanical advantages or disadvantages of altering HR are incompletely understood. We examined the effects of increasing HR on early and late diastole in humans with and without HF.

METHODS AND RESULTS

We studied force-interval relationships of the left ventricle (LV) in 11 HF patients and 14 control subjects. HR was controlled by right atrial pacing, and LV pressure was recorded by a micromanometer-tipped catheter. The time constant of isovolumic relaxation (tau) was calculated, and simultaneous sonographic images were analyzed for LV volumes. The end-diastolic pressure-volume relationship (EDPVR) was analyzed with the use of a single-beat method. Tau was shortened in response to increasing HR in both groups; the slope of this relationship was steeper in HF than in control subjects. The predicted volume at a theoretic pressure of 0 mm Hg (V30) increased at higher HRs compared with baseline, shifting the predicted EDPVR compliance curve to the right in HF patients but not in control subjects.

CONCLUSIONS

In HF, changes in HR affect early relaxation and diastolic compliance to a greater extent than in control subjects. Our study reinforces current recommendations for HR-lowering drug treatment in HF.

Pathophysiology and clinical relevance of pulmonary remodelling in pulmonary hypertension due to left heart diseases

Pulmonary hypertension (PH) in left heart disease, classified as group II, is the most common form of PH that occurs in approximately 60% of cases of reduced and preserved left ventricular ejection fraction. Although relatively much is known about hemodynamic stages (passive or reactive) and their consequences on the right ventricle (RV) there is no consensus on the best hemodynamic definition of group II PH. In addition, the main pathways that lead to lung capillary injury and impaired biology of small artery remodelling processes are largely unknown. Typical lung manifestations of an increased pulmonary pressure and progressive RV-pulmonary circulation uncoupling are an abnormal alveolar capillary gas diffusion, impaired lung mechanics (restriction), and exercise ventilation inefficiency. Of several classes of pulmonary vasodilators currently clinically available, oral phosphodiesterase 5 inhibition, because of its strong selectivity for targeting the cyclic guanosine monophosphate pathway in the pulmonary circulation, is increasingly emerging as an attractive opportunity to reach hemodynamic benefits, reverse capillary injury, and RV remodelling, and improve functional capacity. Guanylate cyclase stimulators offer an additional intriguing opportunity but the lack of selectivity and systemic effects might preclude some of the anticipated benefits on the pulmonary circulation. Future trials will determine whether new routes of pharmacologic strategy aimed at targeting lung structural and vascular remodelling might affect morbidity and mortality in left heart disease populations. We believe that this therapeutic goal rather than a pure hemodynamic effect might ultimately emerge as an important challenge for the clinician.

Impact of chronic congestive heart failure on pharmacokinetics and vasomotor effects of infused nitrite

BACKGROUND AND PURPOSE

Nitrite (NO₂⁻) has recently been shown to represent a potential source of NO, in particular under hypoxic conditions. The aim of the current study was to compare the haemodynamic effects of NO₂⁻ in healthy volunteers and patients with stable congestive heart failure (CHF).

EXPERIMENTAL APPROACH

The acute haemodynamic effects of brachial artery infusion of NO₂⁻ (0.31 to 7.8 μmol·min⁻¹) was assessed in normal subjects (n = 20) and CHF patients (n = 21).

KEY RESULTS

NO₂⁻ infusion was well tolerated in all subjects. Forearm blood flow (FBF) increased markedly in CHF patients at NO₂⁻ infusion rates which induced no changes in normal subjects (ANOVA: F = 5.5; P = 0.02). Unstressed venous volume (UVV) increased even with the lowest NO₂⁻ infusion rate in all subjects (indicating venodilation), with CHF patients being relatively hyporesponsive compared with normal subjects (ANOVA: F = 6.2; P = 0.01). There were no differences in venous blood pH or oxygen concentration between groups or during NO₂⁻ infusion. Venous plasma NO₂⁻ concentrations were lower in CHF patients at baseline, and rose substantially less with NO₂⁻ infusion, without incremental oxidative generation of nitrate, consistent with accelerated clearance in these patients. Plasma protein-bound NO concentrations were lower in CHF patients than normal subjects at baseline. This difference was attenuated during NO₂⁻ infusion. Prolonged NO₂⁻ exposure in vivo did not induce oxidative stress, nor did it induce tolerance in vitro.

CONCLUSIONS AND IMPLICATIONS

The findings of arterial hyper-responsiveness to infused NO₂⁻ in CHF patients, with evidence of accelerated transvascular NO₂⁻ clearance (presumably with concomitant NO release) suggests that NO₂⁻ effects may be accentuated in such patients. These findings provide a stimulus for the clinical exploration of NO₂⁻ as a therapeutic modality in CHF.

The hemodynamic basis of exercise intolerance in tricuspid regurgitation

BACKGROUND

Patients with severe tricuspid regurgitation (TR) frequently present with exertional fatigue and dyspnea, but the hemodynamic basis for exercise limitation in people with TR remains unclear.

METHODS AND RESULTS

Twelve subjects with normal left ventricular (LV) ejection fraction and grade ≥3 TR underwent high-fidelity invasive hemodynamic exercise testing with simultaneous expired gas analysis and were compared with 13 age- and sex-matched controls. At rest, TR subjects had lower pulmonary blood flow (3.6±0.4 versus 5.1±1.9 L/min; P=0.01), increased right atrial pressure (12±5 versus 4±1 mm Hg; P=0.0002), and higher pulmonary capillary wedge pressure (17±5 versus 9±3 mm Hg; P=0.0001). However, LV transmural pressure (pulmonary capillary wedge pressure-right atrial pressure), which reflects LV preload independent of right heart congestion and pericardial restraint, was similar in TR and controls (6±3 versus 4±2 mm Hg; P=0.3). With exercise, TR subjects displayed lower peak VO2 (10.3±2.8 versus 13.8±4.2 mL/min per kg; P=0.02), lower pulmonary blood flow (6.4±1.3 versus 10.3±3.3 L/min; P=0.001), and less increase in pulmonary blood flow relative to VO2 (+4.6±1.1vs +6.2±0.7; P=0.001). TR subjects displayed higher pulmonary capillary wedge pressure with exercise, but this was solely because of RA hypertension (27±9 versus 8±3 mm Hg; P<0.0001), because LV transmural pressure dropped with exercise in subjects with TR (-5±6 versus +3±3 mm Hg; P=0.0007), suggesting inadequate LV diastolic filling, despite high pulmonary capillary wedge pressure.

CONCLUSIONS

Impaired exercise capacity in people with severe TR is related to low cardiac output reserve relative to metabolic needs, coupled with elevated systemic and pulmonary venous pressures. Left heart pressures are elevated with exercise in subjects with TR, despite low LV preload, secondary to enhanced ventricular interaction.