Effect of heart failure on the mechanism of exercise-induced augmentation of mitral valve flow

Distinctive left ventricular-arterial and right ventricular-pulmonary arterial coupling observed in patients with heart failure and a higher left ventricular ejection fraction range

AIMS

Higher left ventricular (LV) ejection fraction (EF) is related to unfavourable prognosis in patients with heart failure (HF) with preserved ejection fraction (HFpEF). The cause of this finding needs to be haemodynamically explained. Thus, we investigated this crucial issue from the perspective of LV-arterial (A) and right ventricular (RV)-pulmonary arterial (PA) coupling.

METHODS AND RESULTS

Study patients were derived from our prospective cohort study of patients hospitalized due to acute decompensated HF and LVEF > 40%. We divided the 255 patients into three groups: HF with mildly reduced EF (HFmrEF), HFpEF with 50% ≤ LVEF < 60%, and HFpEF with LVEF ≥ 60%. We compared LV end-systolic elastance (Ees), effective arterial elastance (Ea), and Ees/Ea as a representative of LV-A coupling among groups and compared the ratio of tricuspid annular plane excursion to peak pulmonary arterial systolic pressure (TAPSE/PASP) as a representative of RV-PA coupling. All-cause death and readmission due to HF-free survival was worse in the group with a higher LVEF range. Ees/Ea was greater in HFpEF patients with LVEF ≥ 60% (2.12 ± 0.57) than in those with 50% ≤ LVEF < 60% (1.20 ± 0.14) and those with HFmrEF (0.82 ± 0.09) (P < 0.001). PASP was increased in the groups with higher LVEF; however, TAPSE/PASP did not differ among groups (n = 168, P = 0.17). In a multivariate Cox proportional hazard model, TAPSE/PASP but not PASP was significantly related to event-free survival independent of LVEF.

CONCLUSION

HFpEF patients with higher LVEF have unfavourable prognosis and distinctive LV-A coupling: Ees/Ea is elevated up to 2.0 or more. Impaired RV-PA coupling also worsens prognosis in such patients.

CLINICAL TRIAL REGISTRATION

URL: https://www.umin.ac.jp/ctr/index.htm Unique identifier: UMIN000017725.

Effects of aging and endurance exercise training on cardiorespiratory fitness and cardiac structure and function in healthy midlife and older women

Cardiovascular disease (CVD) remains the leading cause of morbidity and mortality in women in developed societies. Unfavorable structural and functional adaptations within the heart and central blood vessels with sedentary aging in women can act as the substrate for the development of debilitating CVD conditions such as heart failure with preserved ejection fraction (HFpEF). The large decline in cardiorespiratory fitness, as indicated by maximal or peak oxygen uptake (V̇o2max and V̇o2peak, respectively), that occurs in women as they age significantly affects their health and chronic disease status, as well as the risk of cardiovascular and all-cause mortality. Midlife and older women who have performed structured endurance exercise training for several years or decades of their adult lives exhibit a V̇o2max and cardiac and vascular structure and function that are on par or even superior to much younger sedentary women. Therefore, regular endurance exercise training appears to be an effective preventative strategy for mitigating the adverse physiological cardiovascular adaptations associated with sedentary aging in women. Herein, we narratively describe the aging and short- and long-term endurance exercise training adaptations in V̇o2max, cardiac structure, and left ventricular systolic and diastolic function at rest and exercise in midlife and older women. The role of circulating estrogens on cardiac structure and function is described for consideration in the timing of exercise interventions to maximize beneficial adaptations. Current research gaps and potential areas for future investigation to advance our understanding in this critical knowledge area are highlighted.

Phenotyping heart failure by echocardiography: imaging of ventricular function and haemodynamics at rest and exercise

Traditionally, congestive heart failure (HF) was phenotyped by echocardiography or other imaging techniques according to left ventricular (LV) ejection fraction (LVEF). The more recent echocardiographic modality speckle tracking strain is complementary to LVEF, as it is more sensitive to diagnose mild systolic dysfunction. Furthermore, when LV systolic dysfunction is associated with a small, hypertrophic ventricle, EF is often normal or supernormal, whereas LV global longitudinal strain can reveal reduced contractility. In addition, segmental strain patterns may be used to identify specific cardiomyopathies, which in some cases can be treated with patient-specific medicine. In HF with preserved EF (HFpEF), a diagnostic hallmark is elevated LV filling pressure, which can be diagnosed with good accuracy by applying a set of echocardiographic parameters. Patients with HFpEF often have normal filling pressure at rest, and a non-invasive or invasive diastolic stress test may be used to identify abnormal elevation of filling pressure during exercise. The novel parameter LV work index, which incorporates afterload, is a promising tool for quantification of LV contractile function and efficiency. Another novel modality is shear wave imaging for diagnosing stiff ventricles, but clinical utility remains to be determined. In conclusion, echocardiographic imaging of cardiac function should include LV strain as a supplementary method to LVEF. Echocardiographic parameters can identify elevated LV filling pressure with good accuracy and may be applied in the diagnostic workup of patients suspected of HFpEF.

Unfavourable outcomes in patients with heart failure with higher preserved left ventricular ejection fraction

AIMS

Newly introduced drugs for heart failure (HF) have been reported to improve the prognosis of HF with preserved ejection fraction (HFpEF) in the lower range of left ventricular ejection fraction (LVEF). We hypothesized that a higher LVEF is related to an unfavourable prognosis in patients with HFpEF.

METHODS AND RESULTS

We tested this hypothesis by analysing the data from a prospective multicentre cohort study in 255 patients admitted to the hospital due to decompensated HF (LVEF > 40% at discharge). The primary endpoint of this study was a composite outcome of all-cause death and readmission due to HF, and the secondary endpoint was readmission due to HF. LVEF and the mitral E/e' ratio were measured using echocardiography. In multicovariate parametric survival time analysis, LVEF [hazard ratio (HR) = 1.046 per 1% increase, P = 0.001], concurrent atrial fibrillation (AF) (HR = 3.203, P < 0.001), and E/e' (HR = 1.083 per 1.0 increase, P < 0.001) were significantly correlated with the primary endpoint. In addition to these covariates, angiotensin-converting enzyme inhibitor (ACEI)/angiotensin receptor blocker (ARB) use was significantly correlated with the secondary endpoint (HR = 0.451, P = 0.008). Diagnostic performance plot analysis demonstrated that the discrimination threshold value for LVEF that could identify patients prone to reaching the primary endpoint was ≥57.2%. The prevalence of AF or E/e' ratio did not differ significantly between patients with LVEF ≥ 58% and with 40% < LVEF < 58%.

CONCLUSION

A higher LVEF is independently related to poor prognosis in patients with HFpEF, in addition to concurrent AF and an elevated E/e' ratio. ACEI/ARB use, in contrast, was associated with improved prognosis, especially with regard to readmission due to HF.

CLINICAL TRIAL REGISTRATION

https://www.umin.ac.jp/ctr/index.htm.

UNIQUE IDENTIFIER

UMIN000017725.

Peak apical recoil rate is a simplified index of left ventricular untwist: validation and application for assessment of diastolic function in children

The use of untwisting rate as a novel index of LV diastolic function in clinical practice has been limited due to its tedious and time-consuming analysis. Therefore, we simplify the untwist measurement by only measuring the LV apex's recoil rate and validating and applying peak apical recoil rate (PARR) as an index of diastolic dysfunction (DD) in pediatric subjects during increased and decreased lusitropic states. We recruited 153 healthy subjects (mean age 13.8 ± 2.9 years), of whom 48 performed straight leg raising exercise and an additional 46 patients (mean 8.4 ± 5.6 years) with documented pulmonary capillary wedge pressures (PCWP) (validation cohort). In addition, we studied 16 dilated cardiomyopathy patients (mean age 9.5 ± 6.3 years) (application cohort). PARR and isovolumic relaxation time (IVRT) were compared to PCWP. Both PARR and PARR normalized by heart rate (nPARR) were excellent in detecting patients with PCWP ≥ 12 mmHg and greatly superior to IVRT in this respect (AUC: 0.98, 95% CI [0.96, 1.0] vs. AUC: 0.7 95%CI [0.54,0.86]). In DCM patients, PARR and nPARR were greatly decreased compared to controls (- 38.6 ± 18.6º/s vs - 63.1 ± 16.3º /s, p < 0.001) and (- 0.43 ± 0.20 º/ s/min vs - 0.83 ± 0.28º/s/min, p < 0.0001) but increased with straight leg raising exercise (- 59.4 ± 19.4º/s vs - 97.8 ± 39.0 º/s, p < 0.01) and - 0.85 ± 0.36 vs - 1.4 ± 0.62 º/s/min (p < 0.0001) respectively. PARR and nPARR successfully detected increased and decreased lusitropic states and superior to IVRT in correlation with PCWP. This highly reproducible parameter offers incremental value over traditional indices of DD and may potentially serve as a useful index of elevated PCWP in children.

Multimodality imaging in patients with heart failure and preserved ejection fraction: an expert consensus document of the European Association of Cardiovascular Imaging

Nearly half of all patients with heart failure (HF) have a normal left ventricular (LV) ejection fraction (EF) and the condition is termed heart failure with preserved ejection fraction (HFpEF). It is assumed that in these patients HF is due primarily to LV diastolic dysfunction. The prognosis in HFpEF is almost as severe as in HF with reduced EF (HFrEF). In contrast to HFrEF where drugs and devices are proven to reduce mortality, in HFpEF there has been limited therapy available with documented effects on prognosis. This may reflect that HFpEF encompasses a wide range of different pathological processes, which multimodality imaging is well placed to differentiate. Progress in developing therapies for HFpEF has been hampered by a lack of uniform diagnostic criteria. The present expert consensus document from the European Association of Cardiovascular Imaging (EACVI) provides recommendations regarding how to determine elevated LV filling pressure in the setting of suspected HFpEF and how to use multimodality imaging to determine specific aetiologies in patients with HFpEF.

[The role of diastolic transthoracic stress echocardiography with incremental workload in the evaluation of heart failure with preserved ejection fraction: indications, methodology, interpretation. Expert consensus developed under the auspices of the National Medical Research Center of Cardiology, Society of Experts in Heart Failure (SEHF), and Russian Association of Experts in Ultrasound Diagnosis in Medicine (REUDM)]

Diagnosis of heart failure with preserved ejection fraction (HFpEF) is associated with certain difficulties since many patients with HFpEF have a slight left ventricular diastolic dysfunction and normal filling pressure at rest. Diagnosis of HFpEF is improved by using diastolic transthoracic stress-echocardiography with dosed exercise (or diastolic stress test), which allows detection of increased filling pressure during the exercise. The present expert consensus explains the requirement for using the diastolic stress test in diagnosing HFpEF from clinical and pathophysiological standpoints; defines indications for the test with a description of its methodological aspects; and addresses issues of using the test in special patient groups.

Heart failure with preserved ejection fraction, atrial fibrillation, and increased NT‑proBNP levels : An emergent clinical dilemma

BACKGROUND

The co-presence of atrial fibrillation (AF) in patients with heart failure with preserved ejection fraction (HFpEF) may cause some diagnostic difficulties, because AF itself is associated with elevated levels of N‑terminal pro-B-type natriuretic peptide (NT-proBNP). In the present study we aimed to investigate NT-proBNP levels of patients with HFpEF and AF.

METHODS

This was a retrospective cohort study. Outpatient data were reviewed through the hospital data management system. Consecutive patients with the diagnosis of HFpEF and AF, who had at least one NT-proBNP measurement, were included in the study.

RESULTS

The study population comprised 235 patients. Median NT-proBNP levels were 1242 pg/ml in the stable phase and 2321.5 pg/ml during decompensation. NT-proBNP was correlated positively with age, CHA₂DS₂ and CHA₂DS₂VASc scores, left atrial diameter (LAD), tricuspid annulus diameter, and systolic pulmonary artery pressure but negatively correlated with left ventricular ejection fraction (LVEF) and hemoglobin level. The change in NT-proBNP was positively correlated with heart rate and LAD.

CONCLUSION

Patients with HFpEF and AF have higher levels of NT-proBNP, which may exceed the upper limits defined in guidelines. This study underlines the importance of measuring NT-proBNP levels in the stable phase and proposes a rule-in level for the decompensated phase.

Heart Failure With Preserved Ejection Fraction: A Comprehensive Review and Update of Diagnosis, Pathophysiology, Treatment, and Perioperative Implications

Almost three-quarters of all heart failure patients who are older than 65 have heart failure with preserved ejection fraction (HFpEF). The proportion and hospitalization rate of patients with HFpEF are increasing steadily relative to patients in whom heart failure occurs as result of reduced ejection fraction. The predominance of the HFpEF phenotype most likely is explained by the prevalence of medical conditions associated with an aging population. A multitude of age-related, medical, and lifestyle risk factors for HFpEF have been identified as potential causes for the sustained low-grade proinflammatory state that accelerates disease progression. Profound left ventricular (LV) systolic and diastolic stiffening, elevated LV filling pressures, reduced arterial compliance, left atrial hypertension, pulmonary venous congestion, and microvascular dysfunction characterize HFpEF, but pulmonary arterial hypertension, right ventricular dilation and dysfunction, and atrial fibrillation also frequently occur. These cardiovascular features make patients with HFpEF exquisitely sensitive to the development of hypotension in response to acute declines in LV preload or afterload that may occur during or after surgery. With the exception of symptom mitigation, lifestyle modifications, and rigorous control of comorbid conditions, few long-term treatment options exist for these unfortunate individuals. Patients with HFpEF present for surgery on a regular basis, and anesthesiologists need to be familiar with this heterogeneous and complex clinical syndrome to provide successful care. In this article, the authors review the diagnosis, pathophysiology, and treatment of HFpEF and also discuss its perioperative implications.

Left bundle branch block increases left ventricular diastolic pressure during tachycardia due to incomplete relaxation

We investigated whether tachycardia in left bundle branch block (LBBB) decreases left ventricular (LV) diastolic distensibility and increases diastolic pressures due to incomplete relaxation, and if cardiac resynchronization therapy (CRT) modifies this response. Thirteen canines were studied at baseline heart rate (120 beats/min) and atrial paced tachycardia (180 beats/min) before and after induction of LBBB and during CRT. LV and left atrial pressures (LAP) were measured by micromanometers and dimensions by sonomicrometry. The time constant τ of exponential pressure decay and degree of incomplete relaxation at mitral valve opening (MVO) and end diastole (ED) based on extrapolation of the exponential decay were assessed. Changes in LV diastolic distensibility were investigated using the LV transmural pressure-volume (PV) relation. LBBB caused prolongation of τ (P < 0.03) and increased the degree of incomplete relaxation during tachycardia at MVO (P < 0.001) and ED (P = 0.08) compared with normal electrical activation. This was associated with decreased diastolic distensibility seen as upward shift of the PV relation at MVO by 18.4 ± 7.0 versus 12.0 ± 5.0 mmHg, at ED by 9.8 ± 2.3 versus 4.7 ± 2.3 mmHg, and increased mean LAP to 11.4 ± 2.7 versus 8.5 ± 2.6 mmHg, all P < 0.006. CRT shifted the LV diastolic PV relation downwards during tachycardia, reducing LAP and LV diastolic pressures (P < 0.03). Tachycardia in LBBB reduced LV diastolic distensibility and increased LV diastolic pressures due to incomplete relaxation, whereas CRT normalized these effects. Clinical studies are needed to determine whether a similar mechanism contributes to dyspnea and exercise intolerance in LBBB and if effects of CRT are heart rate dependent.NEW & NOTEWORTHY Compared with normal electrical conduction, tachycardia in left bundle branch block resulted in incomplete relaxation during filling, particularly of the late activated left ventricular lateral wall. This further resulted in reduced left ventricular diastolic distensibility and elevated diastolic pressures and thus amplified the benefits of cardiac resynchronization therapy in this setting.

Exercise Intolerance in Patients With Heart Failure: JACC State-of-the-Art Review

Exercise intolerance is the cardinal symptom of heart failure (HF) and is of crucial relevance, because it is associated with a poor quality of life and increased mortality. While impaired cardiac reserve is considered to be central in HF, reduced exercise and functional capacity are the result of key patient characteristics and multisystem dysfunction, including aging, impaired pulmonary reserve, as well as peripheral and respiratory skeletal muscle dysfunction. We herein review the different modalities to quantify exercise intolerance, the pathophysiology of HF, and comorbid conditions as they lead to reductions in exercise and functional capacity, highlighting the fact that distinct causes may coexist and variably contribute to exercise intolerance in patients with HF.

[Mechanisms of exercise intolerance in patients with heart failure and preserved ejection fraction. Part I: The role of impairments in the left heart chambers]

During exercise an increase in oxygen delivery to working muscles is achieved through well‑coordinated interaction of many organs and systems: the heart, lungs, blood vessels, skeletal muscles, and the autonomic nervous system. In heart failure with preserved left ventricular ejection fraction, all mechanisms involved in the normal exercise tolerance are impaired. In the first part of this review, the impairments of the left heart chambers are considered ‑ left ventricular diastolic dysfunction, the weakening of the contractile and chronotropic reserves, left atrium dysfunction; the possible ways of their medical correction are also presented.

Heart Failure With Preserved Ejection Fraction In Perspective

Approximately half of the patients with signs and symptoms of heart failure have a left ventricular ejection fraction that is not markedly abnormal. Despite the historically initial surprise, heightened risks for heart failure specific major adverse events occur across the broad range of ejection fraction, including normal. The recognition of the magnitude of the problem of heart failure with preserved ejection fraction in the past 20 years has spurred an explosion of clinical investigation and growing intensity of informative outcome trials. This article addresses the historic development of this component of the heart failure syndrome, including the epidemiology, pathophysiology, and existing and planned therapeutic studies. Looking forward, more specific phenotyping and even genotyping of subpopulations should lead to improvements in outcomes from future trials.

Evaluation of left ventricular diastolic function: state of the art after 35 years with Doppler assessment

Left ventricular (LV) diastolic function can be evaluated by echocardiographic indices of LV relaxation/restoring forces, diastolic compliance, and filling pressure. By using a combination of indices, diastolic function can be graded and LV filling pressure estimated with high feasibility and good accuracy. Evaluation of diastolic function is of particular importance in patients with unexplained exertional dyspnea or other symptoms or signs of heart failure which cannot be attributed to impaired LV systolic function and to assess filling pressure in patients with heart failure and reduced LV ejection fraction. Furthermore, grading of diastolic dysfunction can be used for risk assessment in asymptomatic subjects and in patients with heart disease.

Exercise physiology with a left ventricular assist device: Analysis of heart-pump interaction with a computational simulator

Patients with a Ventricular Assist Device (VAD) are hemodynamically stable but show an impaired exercise capacity. Aim of this work is to identify and to describe the limiting factors of exercise physiology with a VAD. We searched for data concerning exercise in heart failure condition and after VAD implantation from the literature. Data were analyzed by using a cardiorespiratory simulator that worked as a collector of inputs coming from different papers. As a preliminary step the simulator was used to reproduce the evolution of hemodynamics from rest to peak exercise (ergometer cycling) in heart failure condition. Results evidence an increase of cardiac output of +2.8 l/min and a heart rate increase to 67% of the expected value. Then, we simulated the effect of a continuous-flow VAD at both rest and exercise. Total cardiac output increases of +3.0 l/min (+0.9 l/min due to the VAD and +2.1 l/min to the native ventricle). Since the left ventricle works in a non-linear portion of the diastolic stiffness line, we observed a consistent increase of pulmonary capillary wedge pressure (from 14 to 20 mmHg) for a relatively small increase of end-diastolic volume (from 182 to 189 cm³). We finally increased VAD speed during exercise to the maximum possible value and we observed a reduction of wedge pressure (-4.5 mmHg), a slight improvement of cardiac output (8.0 l/min) and a complete unloading of the native ventricle. The VAD can assure a proper hemodynamics at rest, but provides an insufficient unloading of the left ventricle and does not prevent wedge pressure from rising during exercise. Neither the VAD provides major benefits during exercise in terms of total cardiac output, which increases to a similar extend to an unassisted heart failure condition. VAD speed modulation can contribute to better unload the ventricle but the maximal flow reachable with the current devices is below the cardiac output observed in a healthy heart.

C-Type Natriuretic Peptide Improves Left Ventricular Functional Performance at Rest and Restores Normal Exercise Responses after Heart Failure

In heart failure (HF), the impaired left ventricular (LV) arterial coupling and diastolic dysfunction present at rest are exacerbated during exercise. C-type natriuretic peptide (CNP) is elevated in HF; however, its functional effects are unclear. We tested the hypotheses that CNP with vasodilating, natriuretic, and positive inotropic and lusitropic actions may prevent this abnormal exercise response after HF. We determined the effects of CNP (2 μg/kg plus 0.4 μg/kg per minute, i.v., 20 minutes) on plasma levels of cGMP before and after HF and assessed LV dynamics during exercise in 10 chronically instrumented dogs with pacing-induced HF. Compared with the levels before HF, CNP infusion caused significantly greater increases in cGMP levels after HF. After HF, at rest, CNP administration significantly reduced LV end-systolic pressure (PES), arterial elastance (EA), and end-diastolic pressure. The peak mitral flow (dV/dtmax) was also increased owing to decreased minimum LVP (LVPmin) and the time constant of LV relaxation (τ) (P < 0.05). In addition, LV contractility (EES) was increased. The LV-arterial coupling (EES/EA) was improved. The beneficial effects persisted during exercise. Compared with exercise in HF preparation, treatment with CNP caused significantly less important increases in PES but significantly decreased τ (34.2 vs. 42.6 ms) and minimum left ventricular pressure with further augmented dV/dtmax Both EES, EES/EA (0.87 vs. 0.32) were increased. LV mechanical efficiency improved from 0.38 to 0.57 (P < 0.05). After HF, exogenous CNP produces arterial vasodilatation and augments LV contraction, relaxation, diastolic filling, and LV arterial coupling, thus improving LV performance at rest and restoring normal exercise responses after HF.

Arrhythmia-Induced Cardiomyopathies: Mechanisms, Recognition, and Management

Arrhythmia-induced cardiomyopathy (AIC) is a potentially reversible condition in which left ventricular dysfunction is induced or mediated by atrial or ventricular arrhythmias. Cellular and extracellular changes in response to the culprit arrhythmia have been identified, but specific pathophysiological mechanisms remain unclear. Early recognition of AIC and prompt treatment of the culprit arrhythmia using pharmacological or ablative techniques result in symptom resolution and recovery of ventricular function. Although cardiomyopathy in response to an arrhythmia may take months to years to develop, recurrent arrhythmia can result in rapid decline in ventricular function with development of heart failure, suggesting residual ultrastructural abnormalities. Reports of sudden death in patients with normalized left ventricular ejection fraction cast doubt on the complete reversibility of this condition. Several aspects of AIC, including specific pathophysiological mechanisms, predisposing factors, optimal therapeutic strategies to prevent ultrastructural changes, and long-term risk of sudden death remain unresolved and need further research.

Role of Diastolic Function in Preserved Exercise Capacity in Patients with Reduced Ejection Fractions

BACKGROUND

Some patients with markedly reduced ejection fractions (EFs) (<35%) have preserved exercise performance greater than predicted for age and gender. Because diastolic function may be a determinant of exercise performance, this study was conducted to test the hypothesis that patients with preserved exercise tolerance despite EFs < 35% may have relatively normal diastolic function.

METHODS

Sixty-five subjects with EFs < 35% who underwent exercise Doppler echocardiography and had no inducible ischemia were retrospectively examined. Forty-five subjects with normal EFs (>60%) and preserved exercise capacity were analyzed as a control group.

RESULTS

Sixteen of 65 patients with EFs < 35% had greater than predicted normal exercise capacity for their age and gender, and the remaining 49 patients had reduced exercise capacity. Patients with reduced EFs and preserved exercise capacity had E/e' ratios (mean, 10 ± 4) similar to those of control subjects (mean, 10 ± 3) and lower than those with reduced exercise tolerance (mean, 16 ± 8) (P < .01). In addition, they had better diastolic filling patterns and smaller left atrial sizes than patients with EFs < 35% and reduced exercise capacity. Multivariate logistic regression analyses indicated that E/e' ratio was an independent predictor of preserved exercise capacity in patients with reduced EFs.

CONCLUSIONS

Relatively intact diastolic function contributes to preserved exercise capacity in patients with reduced EFs (<35%).

Exercise Capacity and Aging

A growing body of literature suggests that regular exercise among older individuals regardless of the degree of frailty, with or without underlying chronic disease, may attenuate the consequences of age-related changes on exercise capacity. The purpose of this article is to review the effects of age-related changes on exercise capacity and the benefits of prescribing exercise to older persons.

Role of echocardiography in clinical hypertension

Hypertension is a major and correctable cardiovascular risk factor. The correct diagnosis of hypertension and precise assessment of cardiovascular risk are essential to give proper treatment in patients with hypertension. Although echocardiography is the second-line study in the evaluation of hypertensive patients, it gives many clues suggesting bad prognosis associated with hypertension, including increased left ventricular (LV) mass, decreased LV systolic function, impaired LV diastolic function, and increased left atrial size and decreased function. Along with conventional echocardiographic methods, tissue Doppler imaging, three-dimensional echocardiography, and strain echocardiography are newer echocardiographic modalities in the evaluation of hypertensive patients in the current echocardiographic laboratories. Understanding conventional and newer echocardiographic parameters is important in the diagnosis and assessment of cardiovascular risk in hypertensive patients.

Preliminary observations of prognostic value of left atrial functional reserve during dobutamine infusion in patients with dilated cardiomyopathy

BACKGROUND

The importance of left atrial (LA) functional reserve in patients with depressed left ventricular function remains unclear. Thus, the aim of this study was to test the hypothesis that diminished augmentation of LA function during dobutamine stress might be associated with cardiovascular events in patients with dilated cardiomyopathy.

METHODS

Eighty-four patients with dilated cardiomyopathy with a mean ejection fraction of 34 ± 9% were retrospectively recruited, and LA strain was determined as the averaged global speckle-tracking longitudinal strain from apical four-chamber and two-chamber views during dobutamine stress (20 μg/kg/min). The systolic component of LA strain was considered to reflect reservoir function, whereas the passive and active emptying components were considered to reflect passive and active emptying function, respectively. Event-free survival was tracked for 17 months.

RESULTS

Multivariate Cox proportional-hazards analysis identified LA volume index (hazard ratio [HR], 1.060; P < .001) and β-blocker use (HR, 0.048; P < .05) as the independent variables associated with cardiovascular events among the baseline parameters and changes in systolic LA strain (HR, 0.971; P = .02), in passive emptying LA strain (HR, 0.942; P < .001), and in left ventricular early diastolic strain rate (HR, 0.986; P = .03) under dobutamine as the variables among the functional reserve parameters. In sequential Cox models, a model based on clinical variables (χ(2) = 9.3) was improved by conventional echocardiographic parameters (χ(2) = 19.2, P = .012) and LA strain parameters at rest (χ(2) = 40.1, P = .005) and further improved by the addition of changes in LA strain parameters under dobutamine (χ(2) = 61.6, P < .001).

CONCLUSIONS

The assessment of LA reservoir and passive emptying function during dobutamine stress provides important incremental prognostic value in patients with dilated cardiomyopathy.

New Insights Into Diastolic Dysfunction and Heart Failure With Preserved Ejection Fraction

As the population ages, the incidence of patients presenting for surgical procedures with diastolic dysfunction and heart failure with preserved ejection fraction will rise. This review will discuss the most current and relevant information on the pathophysiology, treatment, and perioperative management of these patients.

β3-Adrenergic receptor antagonist improves exercise performance in pacing-induced heart failure

In heart failure (HF), the impaired left ventricular (LV) arterial coupling and diastolic dysfunction present at rest are exacerbated during exercise. We have previously shown that in HF at rest stimulation of β3-adrenergic receptors by endogenous catecholamine depresses LV contraction and relaxation. β3-Adrenergic receptors are activated at higher concentrations of catecholamine. Thus exercise may cause increased stimulation of cardiac β3-adrenergic receptors and contribute to this abnormal response. We assessed the effect of L-748,337 (50 μg/kg iv), a selective β3-adrenergic receptor antagonist (β3-ANT), on LV dynamics during exercise in 12 chronically instrumented dogs with pacing-induced HF. Compared with HF at rest, exercise increased LV end-systolic pressure (PES), minimum LV pressure (LVPmin), and the time constant of LV relaxation (τ) with an upward shift of early diastolic portion of LV pressure-volume loop. LV contractility decreased and arterial elastance (EA) increased. LV arterial coupling (EES/EA) (0.40 vs. 0.51) was impaired. Compared with exercise in HF preparation, exercise after β3-ANT caused similar increases in heart rate and PES but significantly decreased τ (34.9 vs. 38.3 ms) and LVPmin with a downward shift of the early diastolic portion of LV pressure-volume loop and further augmented dV/dtmax. Both EES and EES/EA (0.68 vs. 0.40) were increased. LV mechanical efficiency improved from 0.39 to 0.53. In conclusion, after HF, β3-ANT improves LV diastolic filling; increases LV contractility, LV arterial coupling, and mechanical efficiency; and improves exercise performance.

Left ventricular vortex formation is unaffected by diastolic impairment

Normal left ventricular (LV) filling occurs rapidly early in diastole caused by a progressive pressure gradient within the ventricle and with a low left atrial pressure. This normal diastolic function is altered in patients with heart failure. Such impairment of diastolic filling is manifested as an abrupt deceleration of the early filling wave velocity. Although variations within the early filling wave have been observed previously, the underlying hydrodynamic mechanisms are not well understood. Previously, it was proposed that the mitral annulus vortex ring formation time was the total duration of early diastolic filling and provided a measure of the efficiency of diastolic filling. However, we found that the favorable LV pressure difference driving early diastolic filling becomes zero simultaneously with the deceleration of the early filling wave propagation velocity and pinch-off of the LV vortex ring. Thus we calculated the vortex ring formation time using the duration of the early diastolic filling wave from its initiation to the time of the early filling wave propagation velocity deceleration when pinch-off occurs. This formation time does not vary with decreasing intraventricular pressure difference or with degree of diastolic dysfunction. Thus we conclude the vortex ring pinch-off occurs before the completion of early diastole, and its formation time remains invariant to changes of diastolic function.

Effect of healthy aging on left ventricular relaxation and diastolic suction

Doppler ultrasound measures of left ventricular (LV) active relaxation and diastolic suction are slowed with healthy aging. It is unclear to what extent these changes are related to alterations in intrinsic LV properties and/or cardiovascular loading conditions. Seventy carefully screened individuals (38 female, 32 male) aged 21-77 were recruited into four age groups (young: <35; early middle age: 35-49; late middle age: 50-64 and seniors: ≥65 yr). Pulmonary capillary wedge pressure (PCWP), stroke volume, LV end-diastolic volume, and Doppler measures of LV diastolic filling were collected at multiple loading conditions, including supine baseline, lower body negative pressure to reduce LV filling, and saline infusion to increase LV filling. LV mass, supine PCWP, and heart rate were not affected significantly by aging. Measures of LV relaxation, including isovolumic relaxation time and the time constant of isovolumic pressure decay increased progressively, whereas peak early mitral annular longitudinal velocity decreased with advancing age (P < 0.001). The propagation velocity of early mitral inflow, a noninvasive measure of LV suction, decreased with aging with the greatest reduction in seniors (P < 0.001). Age-related differences in LV relaxation and diastolic suction were not attenuated significantly when PCWP was increased in older subjects or reduced in the younger subjects. There is an early slowing of LV relaxation and diastolic suction beginning in early middle age, with the greatest reduction observed in seniors. Because age-related differences in LV dynamic diastolic filling parameters were not diminished significantly with significant changes in LV loading conditions, a decline in ventricular relaxation is likely responsible for the alterations in LV diastolic filling with senescence.

Use and Limitations of E/e' to Assess Left Ventricular Filling Pressure by Echocardiography

Measurement of left ventricular (LV) filling pressure is useful in decision making and prediction of outcomes in various cardiovascular diseases. Invasive cardiac catheterization has been the gold standard in LV filling pressure measurement, but carries the risk of complications and has a similar predictive value for clinical outcomes compared with non-invasive LV filling pressure estimation by echocardiography. A variety of echocardiographic measurement methods have been suggested to estimate LV filling pressure. The most frequently used method for this purpose is the ratio between early mitral inflow velocity and mitral annular early diastolic velocity (E/e'), which has become central in the guidelines for diastolic evaluation. This review will discuss the use the E/e' ratio in prediction of LV filling pressure and its potential pitfalls.

Left intraventricular diastolic and systolic pressure gradients

To describe left ventricular (LV) function comprehensively, it is crucial to characterize precisely transmitral, intraventricular and transaortic pressure–flow relations. The site of measurement is important; as the measurement location is moved from the mitral valve toward the apex and the outflow tract, important regional pressure differences are recorded inside the LV. These intraventricular pressure gradients (IVPGs) play an important role in ventricular filling in the normal heart and may be abolished by systolic or diastolic dysfunction. Despite their apparent importance in ventricular filling and diastolic function, IVPGs have never been utilized in clinical cardiology, due to the complexity of their acquisition. The application of Doppler echocardiography allows the reconstruction of diastolic IVPGs completely non-invasively, thus avoiding the risk and expense of a cardiac catheterization. Regional pressure gradients are also present during ventricular emptying but their correlation with systolic function is not so clear. The current minireview highlights theories and experimental data on invasive and non-invasive assessment of diastolic and systolic IVPGs and their role in LV filling and emptying. We also review the pathophysiological modulation of regional gradients, their importance in understanding and evaluating the complex phenomena underlying ventricular filling, as well as their potential clinical application.

Diastolic relaxation and compliance reserve during dynamic exercise in heart failure with preserved ejection fraction

BACKGROUND

Recent studies have examined haemodynamic changes with stressors such as isometric handgrip and rapid atrial pacing in heart failure with preserved ejection fraction (HFpEF), but little is known regarding left ventricular (LV) pressure-volume responses during dynamic exercise.

OBJECTIVE

To assess LV haemodynamic responses to dynamic exercise in patients with HFpEF.

METHODS

Twenty subjects with normal ejection fraction (EF) and exertional dyspnoea underwent invasive haemodynamic assessment during dynamic exercise to evaluate suspected HFpEF.

RESULTS

LV end-diastolic pressure was elevated at rest (>15 mm Hg, n=18) and with exercise (≥20 mm Hg, n=20) in all subjects, consistent with HFpEF. Heart rate (HR), blood pressure, arterial elastance and cardiac output increased with exercise (all p<0.001). Minimal and mean LV diastolic pressures increased by 43-56% with exercise (both p<0.0001), despite a trend towards a reduction in LV end-diastolic volume (p=0.08). Diastolic filling time was abbreviated with increases in HR and the proportion of diastole that elapsed prior to estimated complete relaxation increased (p<0.0001), suggesting inadequate relaxation reserve relative to the shortening of diastole. LV diastolic chamber elastance acutely increased 50% during exercise (p=0.0003). Exercise increases in LV filling pressures correlated with changes in diastolic relaxation rates, chamber stiffness and arterial afterload but were not related to alterations in preload volume, HR or cardiac output.

CONCLUSION

In patients with newly diagnosed HFpEF, LV filling pressures increase during dynamic exercise in association with inadequate enhancement of relaxation and acute increases in LV chamber stiffness. Therapies that enhance diastolic reserve function may improve symptoms of exertional intolerance in patients with hypertensive heart disease and early HFpEF.

Mechanics of left ventricular relaxation, early diastolic lengthening, and suction investigated in a mathematical model

We investigated the determinants of ventricular early diastolic lengthening and mechanics of suction using a mathematical model of the left ventricle (LV). The model was based on a force balance between the force represented by LV pressure (LVP) and active and passive myocardial forces. The predicted lengthening velocity (e') from the model agreed well with measurements from 10 dogs during 5 different interventions (R = 0.69, P < 0.001). The model showed that e' was increased when relaxation rate and systolic shortening increased, when passive stiffness was decreased, and when the rate of fall of LVP during early filling was decreased relative to the rate of fall of active stress. We first defined suction as the work the myocardium performed to pull blood into the ventricle. This occurred when contractile active forces decayed below and became weaker than restoring forces, producing a negative LVP. An alternative definition of suction is filling during falling pressure, commonly believed to be caused by release of restoring forces. However, the model showed that this phenomenon also occurred when there had been no systolic compression below unstressed length and therefore in the absence of restoring forces. In conclusion, relaxation rate, LVP, systolic shortening, and passive stiffness were all independent determinants of e'. The model generated a suction effect seen as lengthening occurring during falling pressure. However, this was not equivalent with the myocardium performing pulling work on the blood, which was performed only when restoring forces were higher than remaining active fiber force, corresponding to a negative transmural pressure.

Effect of changes in left ventricular diastolic function during exercise on exercise tolerance assessed by exercise-stress tissue Doppler echocardiography

Cardiac function during exercise is assumed to be important in determining exercise tolerance. The aims of this study were to evaluate changes in left ventricular diastolic function (LVDF) during exercise and its effect on exercise tolerance assessed by a noninvasive method, exercise-stress tissue Doppler echocardiography. Twenty-six men with sinus rhythm (controls, hypertension, and cardiomyopathy) underwent cardiopulmonary exercise testing. To assess LVDF during exercise, exercise-stress Doppler echocardiography was performed with a constant workload at rest, and at 50%, 100%, and 120% of anaerobic threshold (AT). Doppler variables related to LVDF increased significantly as the workload increased (P < 0.05). Resting E'correlated significantly with AT (r = 0.424, P = 0.0308) and peak VO(2) (r = 0.471, P = 0.0152). However, the difference in E'between rest and 120% AT (DeltaE') was closely correlated with AT (r = 0.744, P < 0.0001) and peak VO(2) (r = 0.748, P < 0.0001). Moreover, DeltaE'was correlated independently with AT (P = 0.0321) and peak VO(2) (P = 0.0192) by multiple regression analysis. These results suggest that the ability to increase LVDF during exercise is an important factor in determining exercise tolerance.

The cardiac cycle and the physiologic basis of left ventricular contraction, ejection, relaxation, and filling

Heart failure is defined as the pathologic state in which the heart is unable to pump blood at a rate required by the metabolizing tissues or can do so only with an elevated filling pressure. Heart failure in adults most frequently results from the inability of the left ventricle to fill (diastolic performance) or eject (systolic performance) blood. The severity of heart failure and its prognosis are more closely related to the degree of diastolic filling abnormalities than the ejection fraction, which underscores the importance of understanding the mechanisms of diastolic abnormalities in heart failure.

Diastolic Heart Failure in the Elderly

Most elderly patients, particularly women, who have heart failure have a normal ejection fraction. Patients who have this syndrome have severe symptoms of exercise intolerance, frequent hospitalizations, and increased mortality. The pathophysiology and treatment are not well defined. Control of systemic hypertension may be a key to prevention and treatment. Several large trials of specific agents are currently underway.

Current clinical applications of spectral tissue Doppler echocardiography (E/E' ratio) as a noninvasive surrogate for left ventricular diastolic pressures in the diagnosis of heart failure with preserved left ventricular systolic function

Congestive heart failure with preserved left ventricular systolic function has emerged as a growing epidemic medical syndrome in developed countries, which is characterized by high morbidity and mortality rates. Rapid and accurate diagnosis of this condition is essential for optimizing the therapeutic management. The diagnosis of congestive heart failure is challenging in patients presenting without obvious left ventricular systolic dysfunction and additional diagnostic information is most commonly required in this setting. Comprehensive Doppler echocardiography is the single most useful diagnostic test recommended by the ESC and ACC/AHA guidelines for assessing left ventricular ejection fraction and cardiac abnormalities in patients with suspected congestive heart failure, and non-invasively determined basal or exercise-induced pulmonary capillary hypertension is likely to become a hallmark of congestive heart failure in symptomatic patients with preserved left ventricular systolic function. The present review will focus on the current clinical applications of spectral tissue Doppler echocardiography used as a reliable noninvasive surrogate for left ventricular diastolic pressures at rest as well as during exercise in the diagnosis of heart failure with preserved left ventricular systolic function. Chronic congestive heart failure, a disease of exercise, and acute heart failure syndromes are characterized by specific pathophysiologic and diagnostic issues, and these two clinical presentations will be discussed separately.

The effect of acute hypoxia on left ventricular function during exercise

The effect of acute hypoxia on the human left ventricular function during exercise was evaluated by 2D and Doppler echocardiography on 11 healthy male college students. Each subject completed 6-min moderate intensity (100 W) supine cycling exercises in normoxia and hypoxia, respectively. The concentration of inspired O(2) was adjusted to keep arterial hemoglobin O(2) concentration (SpO(2)) at 88-92% during hypoxia. Doppler indices obtained were compared between normoxia and hypoxia. The left ventricular myocardial diastolic function was increased during exercise in hypoxia compared with normoxia. The peak velocity of early filling wave increased at rest (P < 0.05) and during exercise (P < 0.05 at second minute, and P < 0.01 at sixth minute) in hypoxia. The heart rate (P < 0.01) and cardiac output (P < 0.001) were elevated markedly at rest during hypoxia. The left ventricular systolic function variables, such as stroke volume, ejection fraction, and end-systolic volume were relatively unaltered during hypoxia compared with normoxia. The results suggest that acute hypoxia increases the left ventricular myocardial diastolic function during moderate intensity supine cycling exercise without affecting the systolic function.

Diastolic heart failure in the elderly

Most elderly patients, particularly women, who have heart failure have a normal ejection fraction. Patients who have this syndrome have severe symptoms of exercise intolerance, frequent hospitalizations, and increased mortality. The pathophysiology and treatment are not well defined. Control of systemic hypertension may be a key to prevention and treatment. Several large trials of specific agents are currently underway.

Contribution of Systolic and Diastolic Abnormalities to Heart Failure With a Normal and a Reduced Ejection Fraction

Heart failure (HF) has traditionally been divided into HF with a reduced ejection fraction (EF; systolic HF) and HF with a normal EF (diastolic HF). Both groups have reductions in exercise tolerance, neurohumoral activation, and abnormal left ventricular (LV) filling dynamics and impaired relaxation. Although the normal EF indicates that pump performance is adequately compensated, some of the patients with HF and a normal EF have reduced longitudinal systolic velocity indicating cardiac muscular contractile dysfunction. Regardless of EF, the severity of HF and its prognosis and degree of exercise intolerance are closely related to the degree of diastolic filling abnormalities. Patients with HF and a reduced EF have ventricular dilatation and elongated myocytes, whereas patients with HF and a normal EF do not. Thus, patients with HF have diastolic abnormalities regardless of EF and many patients with HF and a normal EF have contractile abnormalities despite preserved systolic pump performance. Heart failure with a normal EF and a reduced EF differs in the systolic LV pump performance and the type of remodeling. The mechanism of the differing remodeling responses is not known, but aging, sex differences, and diabetes may contribute.

Scaling of diastolic intraventricular pressure gradients is related to filling time duration

In early diastole, pressure is lower in the apex than in the base of the left ventricle (LV). This early intraventricular pressure difference (IVPD) facilitates LV filling. We assessed how LV diastolic IVPD and intraventricular pressure gradient (IVPG), defined as IVPD divided by length, scale to the heart size and other physiological variables. We studied 10 mice, 10 rats, 5 rabbits, 12 dogs, and 21 humans by echocardiography. Color Doppler M-mode data were postprocessed to reconstruct IVPD and IVPG. Normalized LV filling time was calculated by dividing filling time by RR interval. The relationship between IVPD, IVPG, normalized LV filling time, and LV end-diastolic volume (or mass) as fit to the general scaling equation Y = kMβ, where M is LV heart size parameter, Y is a dependent variable, k is a constant, and β is the power of the scaling exponent. LV mass varied from 0.049 to 194 g, whereas end-diastolic volume varied from 0.011 to 149 ml. The β values relating normalized LV filling time with LV mass and end-diastolic volume were 0.091 (SD 0.011) and 0.083 (SD 0.009), respectively ( P < 0.0001 vs. 0 for both). The β values relating IVPD with LV mass and end-diastolic volume were similarly significant at 0.271 (SD 0.039) and 0.243 (SD 0.0361), respectively ( P < 0.0001 vs. 0 for both). Finally, β values relating IVPG with LV mass and end-diastolic volume were −0.118 (SD 0.013) and −0.104 (SD 0.011), respectively ( P < 0.0001 vs. 0 for both). As a result, there was an inverse relationship between IVPG and normalized LV filling time ( r = −0.65, P < 0.001). We conclude that IVPD decrease, while IVPG increase with decreasing animal size. High IVPG in small mammals may be an adaptive mechanism to short filling times.

Diastolic Heart Failure Can Be Diagnosed by Comprehensive Two-Dimensional and Doppler Echocardiography

There are many myocardial and non-myocardial conditions that cause heart failure with normal left ventricular ejection fraction (LVEF). Among them, diastolic heart failure (heart failure due to diastolic dysfunction) is the most common cause of heart failure with normal LVEF. Diastolic heart failure easily can be diagnosed by comprehensive two-dimensional and Doppler echocardiography, which can demonstrate abnormal myocardial relaxation, decreased compliance, and increased filling pressure in the setting of normal LV dimensions and preserved LVEF. Therefore, diastolic heart failure should always be considered when LVEF is normal on two-dimensional echocardiography in patients with clinical evidence of heart failure. The diagnosis can be confirmed if Doppler echocardiography and myocardial tissue imaging provide evidence for impaired myocardial relaxation (i.e., decreased longitudinal velocity of the mitral annulus during early diastole and decreased propagation velocity mitral inflow), decreased compliance (shortened mitral A-wave duration and mitral deceleration time), and increased filling pressure (shortened isovolumic relaxation time and an increased ratio between early diastolic mitral and mitral annular velocities). Early identification of diastolic dysfunction in asymptomatic patients by the use of echocardiography may provide an opportunity to manage the underlying etiology to prevent progression to diastolic heart failure.

Ventricular structure and function in aged dogs with renal hypertension: a model of experimental diastolic heart failure

BACKGROUND

Heart failure (HF) with normal ejection fraction (diastolic HF [DHF]) usually occurs in elderly patients with hypertension. The presence and significance of altered systolic and diastolic ventricular function in DHF is increasingly controversial. Our objective was to develop a clinically relevant large-animal model to better understand the pathophysiology of DHF.

METHODS AND RESULTS

Ventricular structure and function were characterized in young control (YC group; n=6), old control (OC group; n=7), and old dogs made hypertensive by renal wrapping (experimental DHF [ExDHF] group; n=8). The ExDHF group was associated with normal left ventricular (LV) volume, increased LV mass, and myocardial fibrosis. LV relaxation was impaired in ExDHF (tau=53+/-6 ms) compared with OC (tau=35+/-3 ms; P<0.05) and YC (tau=33+/-6 ms; P<0.05) dogs. The percent diastole at which relaxation is complete was increased in ExDHF (116+/-30%) compared with OC (69+/-8%; P<0.05) and YC (35+/-5%; P<0.05) dogs. The coefficient of LV diastolic stiffness was similar in OC, YC, and ExDHF dogs. Diastolic pressures increased dramatically in response to increases in blood pressure. End-systolic LV stiffness was enhanced in ExDHF dogs and after load enhancement of myocardial performance was maintained. Arterial stiffness was increased in ExDHF dogs.

CONCLUSIONS

Aged dogs with chronic hypertension exhibit LV hypertrophy and fibrosis with impaired LV relaxation but no increase in the coefficient of LV diastolic stiffness. LV systolic and arterial stiffness are increased, which may exacerbate load-dependent impairment of relaxation and contribute to increased filling pressures with hypertensive episodes. This model mimics many of the structural and functional characteristics described in the limited studies of human DHF and provides insight into the pathogenesis of DHF.

Levosimendan improves LV systolic and diastolic performance at rest and during exercise after heart failure

The new myofilament Ca2+ sensitizer levosimendan (LSM) is a positive inotropic and vasodilatory agent. Its beneficial effects have been demonstrated at rest in congestive heart failure (CHF). However, its effect during exercise (Ex) in CHF is unknown. We assessed the effects of LSM on left ventricular (LV) dynamics at rest and during Ex in eight conscious, instrumented dogs with pacing-induced CHF. After CHF, with dogs at rest, LSM decreased arterial elastance ( Ea) and increased LV contractile performance as assessed by the slope of LV pressure-volume (P-V) relation. LSM caused a >60% increase in the peak rate of mitral flow (dV/d tmax) due to decreases in minimal LV pressure and the time constant of LV relaxation (τ). LV arterial coupling, quantified as the ratio of end-systolic elastance ( Ees) to Ea, was increased from 0.47 to 0.85%. LV mechanical efficiency, determined as the ratio of stroke work to total P-V area, was improved from 0.54 ± 0.09 to 0.61 ± 0.07. These beneficial effects persisted during Ex after CHF. Compared with CHF Ex dogs, treatment with LSM prevented Ex-induced abnormal increases in mean left atrial pressure and end-diastolic pressure and decreased Ees/ Ea. With LSM treatment during CHF Ex, the early diastolic portion of the LV P-V loop was shifted downward with decreased minimal LV pressure and τ values and a further augmented dV/d tmax. Ees/ Ea improved, and mechanical efficiency further increased from 0.61 ± 0.07 to 0.67 ± 0.07, which was close to the value reached during normal Ex. After CHF, LSM produced arterial vasodilatation; improved LV relaxation and diastolic filling; increased contractility, LV arterial coupling, and mechanical efficiency; and normalized the response to Ex.

Endogenous β3-adrenoreceptor activation contributes to left ventricular and cardiomyocyte dysfunction in heart failure

The objective of the present study was to test the hypothesis that endogenous β3-adrenoreceptor (AR) activation contributes to left ventricular (LV) and cardiomyocyte dysfunction in heart failure (CHF). Stimulation of the β3-AR inhibits cardiac contraction. In the failing myocardium, β3-ARs are upregulated, suggesting that stimulation of β3-ARs may contribute to depressed cardiac performance in CHF. We assessed the functional significance of endogenous β3-AR activation in 10 conscious dogs before and after pacing-induced CHF. Under normal conditions, L-748,337, a specific β3-AR antagonist, produced a mild increase in LV contractile performance assessed by the slope ( Ees) of the LV pressure-volume relation (18%, 6.2 ± 0.9 vs. 7.3 ± 1.2 mmHg/ml, P < 0.05) and the improved LV relaxation time constant (τ; 28.4 ± 1.9 vs. 26.8 ± 1.0 ms, P < 0.05). After CHF, the plasma norepinephrine concentration increased eightfold, and L-748,337 produced a larger increase in Ees (34%, 3.8 ± 0.7 vs. 5.1 ± 0.8 mmHg/ml, P < 0.05) and a greater decrease in τ (46.4 ± 4.2 vs. 41.0 ± 3.9 ms, P < 0.05). Similar responses were observed in isolated myocytes harvested from LV biopsies before and after CHF. In the normal myocyte, L-748,337 did not cause significant changes in contraction or relengthening. In contrast, in CHF myocytes, L-748,337 produced significant increases in contraction (5.8 ± 0.9 vs. 6.8 ± 0.9%, P < 0.05) and relengthening (33.5 ± 4.2 vs. 39.7 ± 4.0 μm/s, P < 0.05). The L-748,337-induced myocyte response was associated with improved intracellular Ca2+ concentration regulation. In CHF myocytes, nadolol caused a decrease in contraction and relengthening, and adding isoproterenol to nadolol caused a further depression of myocyte function. Stimulation of β3-AR by endogenous catecholamine contributes to the depression of LV contraction and relaxation in CHF.

Diastolic mitral annular velocity during the development of heart failure

OBJECTIVES

We sought to investigate the mechanism of reduced diastolic mitral annular velocity with diastolic dysfunction, despite elevated left atrial (LA) pressure.

BACKGROUND

The peak rate of left ventricular (LV) early diastolic filling (E) and velocity of the mitral annulus due to long-axis lengthening (E(M)) are reduced in mild diastolic dysfunction. With more severe dysfunction, E increases in response to increased LA pressures. In contrast, E(M) decreases, despite increased LA pressure.

METHODS

We studied eight dogs instrumented to measure LA pressure, LV pressure, and internal dimensions during the progressive development of heart failure (HF) produced by rapid pacing.

RESULTS

Early diastolic filling decreased after four days of pacing from 114 +/- 32 to 88 +/- 22 ml/s (p < 0.05), but with more severe HF, it progressively increased to 155 +/- 32 ml/s (p < 0.05). In contrast, E(M) progressively decreased from 44 +/- 12 mm/s during the control period to 24 +/- 8 mm/s after four weeks (p < 0.05). Although E(M) was related to the time constant of LV relaxation (tau) (R(2) = 0.85), E was not. The latter occurred coincident with termination of the early diastolic LA to LV pressure gradient during all conditions. In contrast, with increasing HF, E(M) was progressively delayed after LA to LV pressure crossover by 37 +/- 12 ms (p < 0.05). The time from E to E(M) was related to tau (R(2) = 0.97).

CONCLUSIONS

With slowed relaxation during the development of HF, E(M) is reduced and delayed so that it occurs after early, rapid filling. Thus, with slowed relaxation, E(M) does not respond to the early diastolic LA to LV pressure gradient, because it occurs when LV pressure is greater than or equal to LA pressure.