Influence of Vascular Function and Pulsatile Hemodynamics on Cardiac Function

Abnormal Cardiac Magnetic Resonance-Derived Ascending Aortic Area Strain Demonstrates Altered Ventriculo-Vascular Function in Marfan Syndrome

PURPOSE

There remains a need for improved imaging markers for risk stratification and treatment guidance in Marfan syndrome (MFS). After aortic root replacement (ARR), vascular remodeling and progressive aneurysm formation can occur due to alterations in up- and downstream wall biomechanics and hemodynamics. We aim to compare the ventriculo-vascular properties of patients with MFS with controls, and investigate the correlation between ascending aortic area strain and descending aortic area strain (DAAS) with other clinical variables.

PATIENTS AND METHODS

Nineteen patients with MFS (47% males), including 6 with ARR were studied. In 26 studies, aortic area strain was measured using cross-sectional cardiac magnetic resonance images at the ascending and proximal descending aortic levels. Left atrial, left ventricular longitudinal, and left ventricle circumferential strain (left atrial longitudinal strain, left ventricular longitudinal strain, and left ventricular circumferential strain, respectively) were measured using cardiac magnetic resonance-feature tracking.

RESULTS

Compared with healthy controls, patients with MFS had significantly impaired left ventricular longitudinal strain and left ventricular circumferential strain (-15.8 ± 4.7 vs -19.7 ± 4.8, P = 0.005, and -17.7 ± 4.0 vs -27.0 ± 4.1, P < 0.001). Left atrial longitudinal strain was comparable between patients with MFS and controls. AAAS was significantly reduced (19.0 [11.9, 23.7] vs 46.1 ± 11.3, P < 0.001), whereas DAAS was not significantly decreased. AAAS and DAAS were negatively correlated with age, whereas no significant associations were identified with left ventricle function indices. No significant differences were observed between the ventriculo-vascular properties of patients with MFS who underwent ARR and those who did not.

CONCLUSION

Patients with MFS demonstrated impaired ventricular and vascular function compared with healthy controls. Further investigations are warranted to determine clinical utility of aortic stiffness indices for predicting primary and repeat aortic events.

Mechanistic insights on age-related changes in heart-aorta-brain hemodynamic coupling using a pulse wave model of the entire circulatory system

Age-related changes in aortic biomechanics can impact the brain by reducing blood flow and increasing pulsatile energy transmission. Clinical studies have shown that impaired cardiac function in patients with heart failure is associated with cognitive impairment. Although previous studies have attempted to elucidate the complex relationship between age-associated aortic stiffening and pulsatility transmission to the cerebral network, they have not adequately addressed the effect of interactions between aortic stiffness and left ventricle (LV) contractility (neither on energy transmission nor on brain perfusion). In this study, we use a well-established and validated one-dimensional blood flow and pulse wave computational model of the circulatory system to address how age-related changes in cardiac function and vasculature affect the underlying mechanisms involved in the LV-aorta-brain hemodynamic coupling. Our results reveal how LV contractility affects pulsatile energy transmission to the brain, even with preserved cardiac output. Our model demonstrates the existence of an optimal heart rate (near the normal human heart rate) that minimizes pulsatile energy transmission to the brain at different contractility levels. Our findings further suggest that the reduction in cerebral blood flow at low levels of LV contractility is more prominent in the setting of age-related aortic stiffening. Maintaining optimal blood flow to the brain requires either an increase in contractility or an increase in heart rate. The former consistently leads to higher pulsatile power transmission, and the latter can either increase or decrease subsequent pulsatile power transmission to the brain.NEW & NOTEWORTHY We investigated the impact of major aging mechanisms of the arterial system and cardiac function on brain hemodynamics. Our findings suggest that aging has a significant impact on heart-aorta-brain coupling through changes in both arterial stiffening and left ventricle (LV) contractility. Understanding the underlying physical mechanisms involved here can potentially be a key step for developing more effective therapeutic strategies that can mitigate the contributions of abnormal LV-arterial coupling toward neurodegenerative diseases and dementia.

Heart Failure with Preserved Left Ventricular Ejection Fraction: A Complex Conundrum Simply Not Limited to Diastolic Dysfunction

Over the last two decades, the changing paradigm of heart failure with preserved ejection fraction (HFpEF) has transformed our understanding not only of the pathophysiology of this clinical entity but also the diagnostic and therapeutic approaches aimed at treating this complex patient population. No longer HFpEF should be seen as simply left ventricular diastolic dysfunction but as a group of that in addition of having small and thick left ventricles with abnormal diastolic filling patterns as their main pathophysiologic abnormality; they also have whole host of different abnormalities. In fact, this heterogeneous clinical entity embodies numerous mechanisms and is linked to multiorgan dysfunction, with hypertension and obesity playing a major role. Although we have gained an enormous amount of understanding not only on the causes but also the downstream effects of HFpEF, there is still much to be learned before we can fully comprehend this complex clinical entity. It is the main intention of this review to synthesize the most recent attributes, mechanism, diagnostic tools, and most useful therapeutic alternatives to be considered when evaluating patients either complaining of dyspnea on exertion as well as exercise intolerance or those recently admitted with HF symptoms but with normal LVEF in the absence of any other valvular abnormalities.

A coupled atrioventricular-aortic setup for in-vitro hemodynamic study of the systemic circulation: Design, fabrication, and physiological relevancy

In-vitro models of the systemic circulation have gained a lot of interest for fundamental understanding of cardiovascular dynamics and for applied hemodynamic research. In this study, we introduce a physiologically accurate in-vitro hydraulic setup that models the hemodynamics of the coupled atrioventricular-aortic system. This unique experimental simulator has three major components: 1) an arterial system consisting of a human-scale artificial aorta along with the main branches, 2) an artificial left ventricle (LV) sac connected to a programmable piston-in-cylinder pump for simulating cardiac contraction and relaxation, and 3) an artificial left atrium (LA). The setup is designed in such a way that the basal LV is directly connected to the aortic root via an aortic valve, and to the LA via an artificial mitral valve. As a result, two-way hemodynamic couplings can be achieved for studying the effects that the LV, aorta, and LA have on each other. The collected pressure and flow measurements from this setup demonstrate a remarkable correspondence to clinical hemodynamics. We also investigate the physiological relevancies of isolated effects on cardiovascular hemodynamics of various major global parameters found in the circulatory system, including LV contractility, LV preload, heart rate, aortic compliance, and peripheral resistance. Subsequent control over such parameters ultimately captures physiological hemodynamic effects of LV systolic dysfunction, preload (cardiac) diseases, and afterload (arterial) diseases. The detailed design and fabrication of the proposed setup is also provided.

Long-term cardiac pathology in individuals with mild initial COVID-19 illness

Cardiac symptoms are increasingly recognized as late complications of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection in previously well individuals with mild initial illness, but the underlying pathophysiology leading to long-term cardiac symptoms remains unclear. In this study, we conducted serial cardiac assessments in a selected population of individuals with Coronavirus Disease 2019 (COVID-19) with no previous cardiac disease or notable comorbidities by measuring blood biomarkers of heart injury or dysfunction and by performing magnetic resonance imaging. Baseline measurements from 346 individuals with COVID-19 (52% females) were obtained at a median of 109 days (interquartile range (IQR), 77-177 days) after infection, when 73% of participants reported cardiac symptoms, such as exertional dyspnea (62%), palpitations (28%), atypical chest pain (27%) and syncope (3%). Symptomatic individuals had higher heart rates and higher imaging values or contrast agent accumulation, denoting inflammatory cardiac involvement, compared to asymptomatic individuals. Structural heart disease or high levels of biomarkers of cardiac injury or dysfunction were rare in symptomatic individuals. At follow-up (329 days (IQR, 274-383 days) after infection), 57% of participants had persistent cardiac symptoms. Diffuse myocardial edema was more pronounced in participants who remained symptomatic at follow-up as compared to those who improved. Female gender and diffuse myocardial involvement on baseline imaging independently predicted the presence of cardiac symptoms at follow-up. Ongoing inflammatory cardiac involvement may, at least in part, explain the lingering cardiac symptoms in previously well individuals with mild initial COVID-19 illness.

Determining patterns of vascular function and structure in wild-type transthyretin cardiac amyloidosis. A comparative study

BACKGROUND

The impact of wild-type transthyretin-related cardiac amyloidosis (ATTRwt) on functional and structural peripheral vascular measures is unknown. In the present study, we explored patterns of vascular dysfunction in patients with ATTRwt in comparison to diseases with similar cardiac phenotype.

METHODS

Treatment-naïve patients with ATTRwt (n = 32) were compared to: 1. Age-and sex-matched reference population without amyloidosis (n = 32), 2. Age-and sex-matched patients with systemic AL amyloidosis (n = 32), and 3. patients with cardiac AL amyloidosis (AL-HF, n = 23) or elderly patients with heart failure with preserved ejection fraction (HFpEF) (n = 16). All subjects underwent peripheral vascular assessment using carotid artery ultrasonography, brachial artery flow-mediated dilation (FMD), measurement of arterial stiffness and aortic hemodynamics including heart rate-adjusted time of return of reflected waves (Tr/HR).

RESULTS

After adjustment for traditional cardiovascular risk factors and coronary artery disease (core model), peripheral and aortic blood pressures (BP) were lower in patients with ATTRwt (p < 0.05) whereas other vascular markers were preserved compared to the reference non-amyloidosis group. ATTRwt was independently associated with lower BP and longer Tr/HR compared to AL. Compared to AL-HF, FMD was lower in ATTRwt (p = 0.033). ATTRwt patients had lower BP and higher Tr/HR than HFpEF (p < 0.05). By ROC analysis, Tr/HR discriminated ATTRwt vs. AL-HF (sensitivity 93%, specificity 75%) and HFpEF (sensitivity 100%, specificity 94%) and lower FMD increased the likelihood for ATTRwt at low Tr/HR values.

CONCLUSION

ATTRwt patients present a distinct peripheral vascular fingerprint which is different from AL-HF or HFpEF, consisting of lower peripheral and aortic BP, prolonged Tr/HR and FMD at reference-population range.

Aortic Stiffness and Pulsatile Pressures as Potential Mediators of Chronic Kidney Disease Induced Impaired Diastolic Function

Purpose

We assessed whether aortic stiffness and pulsatile pressures can mediate chronic kidney disease (CKD)-associated impaired diastolic function.

Participants and Methods

In 276 black Africans including 46 CKD (19 non-dialysis; 27 dialysis) and 230 control subjects, pulse wave velocity (PWV) estimated aortic stiffness and pulsatile pressures (forward and backward wave pressure, central systolic blood pressure (CSBP) and pulse pressure (CPP)) were determined by applanation tonometry; e’ as an index of left ventricular active relaxation and E/e’ as a measure of left ventricular filling pressure or passive relaxation were evaluated by echocardiography.

Results

In age, sex, traditional cardiovascular risk factor and mean arterial pressure (MAP) adjusted regression models, CKD was inversely associated with e’ (p = 0.03) and directly with E/e’ (p < 0.01). The CKD-e’ relationship was attenuated and no longer significant (p = 0.31) upon additional adjustment for aortic PWV but not pulsatile pressures (p = 0.03–0.05). In product of coefficient mediation analysis, PWV accounted for 47.6% of the CKD-e’ association. CSBP (22.9%) and CPP (18.6%) but not PWV (11.3%) accounted for a significant and relevant proportion of the CKD-E/e’ relationship. However, CKD remained strongly associated with E/e’ independent of aortic function measures (p < 0.01). Treatable covariates that were or tended to be consistently associated with diastolic function included MAP (p < 0.01) and diabetes (p = 0.02–0.07) for the CKD-e’ and CKD-E/e’ relations, respectively.

Conclusion

Aortic stiffness rather than pulsatile pressures mediates CKD-related impaired left ventricular active relaxation. By contrast, aortic pulsatile pressures (and not stiffness) contribute to CKD-related left ventricular filling pressures but do not fully account for the respective association.

Nebivolol for the Treatment of Essential Systemic Arterial Hypertension: A Systematic Review and Meta-Analysis

INTRODUCTION

Cardiovascular diseases are the main cause of mortality worldwide, and systemic arterial hypertension is associated with a large number of these cases. The objective of health professionals and health policies should be searching for the best therapeutics to control this disease. A recent consensus indicated that β-blockers have recently lost their place in initial indications for the treatment of systemic arterial hypertension and are now more indicated for the treatment of hypertension in association with other clinical situations such as angina, heart failure and arrhythmia; however, it is known that this approach was based on studies that evaluated older β-blockers such as atenolol.

OBJECTIVE

The main objective of this study was to perform a systematic review with subsequent meta-analysis on the use of nebivolol for hypertensive disease treatment, comparing it with drugs of the main antihypertensive classes.

METHODS

This systematic review was based on a search of the MEDLINE (via Pubmed), Scopus, Cochrane, International Pharmaceuticals Abstracts (IPA), and Lilacs databases for randomized and double-blind clinical trials. In addition, we also searched for gray literature studies, to 31 July 2015. Next, a cumulative meta-analysis was performed, with studies being added in a sequential manner, evaluating their impact on the combined effect. For this project, we only meta-analyzed direct comparisons of random effect.

RESULTS

Overall, 981 clinical trials were included in this systematic review. After careful analysis, 34 randomized and double-blind clinical trials were included to investigate the efficacy of nebivolol on systolic (SBP) and diastolic blood pressure (DBP) control and adverse effects. The study population comprised 12,465 patients with systemic arterial hypertension (SAH) aged between 18 and 85 years; 17% of subjects were of Black ethnicity, approximately 55% were men, and almost 10% had diabetes. In SBP management, nebivolol was superior to other β-blockers and diuretics and showed no difference in efficacy when compared with angiotensin receptor blockers or calcium channel blockers. There were insufficient studies on angiotensin-converting enzyme inhibitors for adequate comparison of both SBP and DBP control. For DBP control, nebivolol was more efficient than other β-blockers, angiotensin receptor blockers, diuretics, and calcium channel blockers.

DISCUSSION

Nebivolol is a third-generation β-blocker with additional capabilities to improve blood pressure levels in patients with arterial hypertension, because it acts by additional mechanisms such as endothelium-dependent vasodilation associated with L-arginine and oxide nitric acid, nitric oxide activity on smooth muscle cells, decreasing platelet aggregation, and leukocyte adhesion in the endothelium, decreasing oxidative stress. Although nebivolol has shown good results in controlling hypertension in this study (with few adverse events when compared with placebo treatment) and has an unquestionable benefit in individuals with heart failure (mainly with reduced ejection fraction), there is a lack of studies proving the benefit of this drug for controlling hypertension and reducing clinical outcomes such as cardiovascular (or general) mortality, acute myocardial infarction, or stroke.

CONCLUSIONS

Nebivolol demonstrated at least similar control of blood pressure levels in hypertensive individuals when compared with drugs of the most used classes. In addition, in relation to the control of arterial hypertension, studies with clinical outcomes should be performed to ensure the use of this drug in detriment to others with these well-established results.

Aortic root movement correlation with the function of the left ventricle

Echocardiographic assessment of systolic and diastolic function of the heart is often limited by image quality. However, the aortic root is well visualized in most patients. We hypothesize that the aortic root motion may correlate with the systolic and diastolic function of the left ventricle of the heart. Data obtained from 101 healthy volunteers (mean age 46.6 ± 12.4) was used in the study. The data contained sequences of standard two-dimensional (2D) echocardiographic B-mode (brightness mode, classical ultrasound grayscale presentation) images corresponding to single cardiac cycles. They also included sets of standard echocardiographic Doppler parameters of the left ventricular systolic and diastolic function. For each B-mode image sequence, the aortic root was tracked with use of a correlation tracking algorithm and systolic and diastolic values of traveled distances and velocities were determined. The aortic root motion parameters were correlated with the standard Doppler parameters used for the assessment of LV function. The aortic root diastolic distance (ARDD) mean value was 1.66 ± 0.26 cm and showed significant, moderate correlation (r up to 0.59, p < 0.0001) with selected left ventricular diastolic Doppler parameters. The aortic root maximal diastolic velocity (ARDV) was 10.8 ± 2.4 cm/s and also correlated (r up to 0.51, p < 0.0001) with some left ventricular diastolic Doppler parameters. The aortic root systolic distance (ARSD) was 1.63 ± 0.19 cm and showed no significant moderate correlation (all r values < 0.40). The aortic root maximal systolic velocity (ARSV) was 9.2 ± 1.6 cm/s and correlated in moderate range only with peak systolic velocity of medial mitral annulus (r = 0.44, p < 0.0001). Based on these results, we conclude, that in healthy subjects, aortic root motion parameters correlate significantly with established measurements of left ventricular function. Aortic root motion parameters can be especially useful in patients with low ultrasound image quality precluding usage of typical LV function parameters.

Arterial Stiffness in Aging: Does It Have a Place in Clinical Practice?: Recent Advances in Hypertension

Aortic stiffness increases markedly with age and is associated with excess risk for various adverse clinical outcomes, including heart disease, dementia, and kidney disease. Although evidence for adverse effects of aortic stiffening is overwhelming, integration of direct and indirect measures of aortic stiffness into routine clinical assessment has lagged behind the science. This brief review will examine recent evidence supporting the value of stiffness as an important new risk factor for hypertension and cardiovascular disease and will offer suggestions for incorporating stiffness measures into routine clinical practice.

Insights on the Pathogenesis of Aneurysm through the Study of Hereditary Aortopathies

Thoracic aortic aneurysms (TAA) are permanent and localized dilations of the aorta that predispose patients to a life-threatening risk of aortic dissection or rupture. The identification of pathogenic variants that cause hereditary forms of TAA has delineated fundamental molecular processes required to maintain aortic homeostasis. Vascular smooth muscle cells (VSMCs) elaborate and remodel the extracellular matrix (ECM) in response to mechanical and biochemical cues from their environment. Causal variants for hereditary forms of aneurysm compromise the function of gene products involved in the transmission or interpretation of these signals, initiating processes that eventually lead to degeneration and mechanical failure of the vessel. These include mutations that interfere with transduction of stimuli from the matrix to the actin-myosin cytoskeleton through integrins, and those that impair signaling pathways activated by transforming growth factor-β (TGF-β). In this review, we summarize the features of the healthy aortic wall, the major pathways involved in the modulation of VSMC phenotypes, and the basic molecular functions impaired by TAA-associated mutations. We also discuss how the heterogeneity and balance of adaptive and maladaptive responses to the initial genetic insult might contribute to disease.

Age-related values of aortic pulse wave velocity in healthy subjects measured by Doppler echocardiography

Aortic pulse wave velocity (aPWV) is a measure of aortic stiffness, which is an indicator of vascular aging and prognostic marker for cardiovascular complications. aPWV can be measured with various methods, but with different reference values depending on the technique used. Therefore, we decided to evaluate age-related values of aPWV, measured by Doppler echocardiography. We included 134 healthy adults (mean age 44.1 ± 13.2 years, 54% of females) divided into five groups based on age decades (D1 21-30 years, n = 29; D2 31-40 years, n = 24; D3 41-50 years, n = 34; D4 51-60 years, n = 25; and D5 61-70 years, n = 22). With the use of a cardiac probe and ECG tracing, ten Doppler waveforms were sequentially recorded, first in the distal aortic arch, and than in the left external iliac artery. Transit time was measured as a delay of the foot of the Doppler waveform in the distal, relative to the proximal location. The distance was measured over the body surface. aPWV was calculated as distance/transit time. Median aPWV in the whole group was 5.05 m/s [4.55-5.99] and did not differ according to sex (females, 5.28 m/s [4.50-6.1] vs. males, 4.95 m/s [4.59-5.77], p = 0.46). Mean aPWV values with 95% confidence intervals (95% CI) for each decade were as follows: D1, 4.54 m/s (4.37-4.72), D2, 4.61 m/s (4.36-4.87), D3, 5.11 m/s (4.89-5.33), D4, 6.04 m/s (5.63-6.45), and D5, 6.77 m/s (6.35-7.19). We report age-related values of aPWV, in a healthy population, measured by Doppler echocardiography. This may be helpful in future research exploring the associations between aortic stiffness, cardiac function, and cardiovascular risk.

Proximal aorta longitudinal strain predicts aortic root dilation rate and aortic events in Marfan syndrome

AIMS

Life expectancy in Marfan syndrome patients has improved thanks to the early detection of aortic dilation and prophylactic aortic root surgery. Current international clinical guidelines support the use of aortic root diameter as a predictor of complications. However, other imaging markers are needed to improve risk stratification. This study aim to ascertain whether proximal aorta longitudinal and circumferential strain and distensibility assessed by cardiac magnetic resonance (CMR) predict the aortic root dilation rate and aortic events in Marfan syndrome.

METHODS AND RESULTS

One hundred and seventeen Marfan patients with no previous aortic dissection, cardiac/aortic surgery, or moderate/severe aortic regurgitation were prospectively included in a multicentre protocol of clinical and imaging follow-up. At baseline, CMR was performed and proximal aorta longitudinal strain and ascending aorta circumferential strain and distensibility were obtained. During follow-up (85.7 [75.0-93.2] months), the annual growth rate of aortic root diameter was 0.62 ± 0.65 mm/year. Fifteen patients underwent elective surgical aortic root replacement and four presented aortic dissection. Once corrected for baseline clinical and demographic characteristics and aortic root diameter, proximal aorta longitudinal strain, but not circumferential strain and distensibility, was an independent predictor of the aortic root diameter growth rate (P = 0.001, P = 0.823, and P = 0.997, respectively), z-score growth rate (P = 0.013, P = 0.672, and P = 0.680, respectively), and aortic events (P = 0.023, P = 0.096, and P = 0.237, respectively).

CONCLUSION

Proximal aorta longitudinal strain is independently related to the aortic root dilation rate and aortic events in addition to aortic root diameter, clinical risk factors, and demographic characteristics in Marfan syndrome patients.

Female Heart Health: Is GPER the Missing Link?

The G Protein-Coupled Estrogen Receptor (GPER) is a novel membrane-bound receptor that mediates non-genomic actions of the primary female sex hormone 17β-estradiol. Studies over the past two decades have elucidated the beneficial actions of this receptor in a number of cardiometabolic diseases. This review will focus specifically on the cardiac actions of GPER, since this receptor is expressed in cardiomyocytes as well as other cells within the heart and most likely contributes to estrogen-induced cardioprotection. Studies outlining the impact of GPER on diastolic function, mitochondrial function, left ventricular stiffness, calcium dynamics, cardiac inflammation, and aortic distensibility are discussed. In addition, recent data using genetic mouse models with global or cardiomyocyte-specific GPER gene deletion are highlighted. Since estrogen loss due to menopause in combination with chronological aging contributes to unique aspects of cardiac dysfunction in women, this receptor may provide novel therapeutic effects. While clinical studies are still required to fully understand the potential for pharmacological targeting of this receptor in postmenopausal women, this review will summarize the evidence gathered thus far on its likely beneficial effects.

Aortic stiffness, pressure and flow pulsatility, and target organ damage

Measures of aortic stiffness and pressure and flow pulsatility have emerged as correlates of and potential contributors to cardiovascular disease, dementia, and kidney disease. Higher aortic stiffness and greater pressure and flow pulsatility are associated with excessive pulsatile load on the heart, which increases mass and reduces global longitudinal strain of the left ventricle. Excessive stiffness and pulsatility are also associated with microvascular lesions in high-flow organs, such as the brain and kidney, suggesting that small vessels in these organs are damaged by pulsatility. This brief review will summarize evidence relating aortic stiffness to cardiovascular, brain, and kidney disease.

Measurement Repeatability of Central and Peripheral Blood Pressures: The ARIC Study

BACKGROUND

Central systolic and pulse pressures are markers of risk for small vessel disease in the brain and kidneys. The extent to which these markers are reproducible in the setting of population studies is less well established. We estimated short-term repeatability of central systolic and pulse pressures, and those of their peripheral measures for comparison.

METHODS

Participants aged 65 years and over (n = 79, 56% women) were drawn from the 2011-2013 examination of the ARIC cohort. Measurements were obtained with automated devices in the supine position, except for conventional sitting pressures, from paired measurements at each of 2 visits separated by 4 to 8 weeks. Three-level variance component models with between-participant, between-visit, and within-visit components estimated reliability metrics.

RESULTS

Mean central systolic and pulse pressures were higher than conventional brachial measures, yet their 4 to 8 week measurement repeatability was similar: reliability coefficients were 0.62 (95% confidence interval: 0.49, 0.74) and 0.63 (0.51, 0.76) for central and sitting brachial systolic pressures, and 0.66 (0.54. 0.77) and 0.73 (0.63, 0.82) for their corresponding pulse pressures. Between-participant variation contributed to two-thirds of the short-term repeatability for all measures. Within-visit variation remained uniformly low across visits.

CONCLUSIONS

Our results indicate that the average of 2 standardized measurements obtained at a single visit can provide reliable estimates of central systolic and pulse pressures. The reliability coefficients of central and peripheral blood pressure measures were comparable. Estimates are presented of minimal detectable change and difference to aid in study design and evaluation of analytic results.

Ultrasonographic and histological evaluation of the effects of long-term carotid catheterization on cardiac function in NMRI mice

Catheterization of laboratory mice is commonly performed in biomedical research to infuse substances and for blood sampling. One approach is to catheterize the right common carotid artery and advance the catheter until the tip is positioned in the aorta or the proximal brachiocephalic trunk. Owing to the small body size of the mouse, a catheter tends to occupy a great part of even the larger vessel lumens, and this may increase vascular resistance with potential pathophysiological impacts on the heart. The present study compared cardiac function of catheterized mice, with catheter tip placement in the brachiocephalic trunk, with sham-operated mice and non-operated control mice. During four weeks post-catheterization, M-mode echocardiography measurements of the thickness of the left ventricular anterior wall, left ventricular inner diameter and the thickness of the left ventricular posterior wall were performed. The left ventricular volume, ejection fraction and fractional shortening were calculated. Moreover, aortic recordings of the thickness of the medial and lateral walls as well as the inner diameter were measured. Terminally, histological analysis of the hearts was conducted, and body weights and heart weights were compared between groups. No effects on echocardiography parameters, histology, body weights or cardiac weights could be found between groups. In the present study, implantation of a carotid catheter with catheter tip placement in the proximal brachiocephalic trunk had minimal influence on cardiac and aortic physiology and did not induce significant cardiac changes.

Hydraulic forces contribute to left ventricular diastolic filling

Myocardial active relaxation and restoring forces are known determinants of left ventricular (LV) diastolic function. We hypothesize the existence of an additional mechanism involved in LV filling, namely, a hydraulic force contributing to the longitudinal motion of the atrioventricular (AV) plane. A prerequisite for the presence of a net hydraulic force during diastole is that the atrial short-axis area (ASA) is smaller than the ventricular short-axis area (VSA). We aimed (a) to illustrate this mechanism in an analogous physical model, (b) to measure the ASA and VSA throughout the cardiac cycle in healthy volunteers using cardiovascular magnetic resonance imaging, and (c) to calculate the magnitude of the hydraulic force. The physical model illustrated that the anatomical difference between ASA and VSA provides the basis for generating a hydraulic force during diastole. In volunteers, VSA was greater than ASA during 75-100% of diastole. The hydraulic force was estimated to be 10-60% of the peak driving force of LV filling (1-3 N vs 5-10 N). Hydraulic forces are a consequence of left heart anatomy and aid LV diastolic filling. These findings suggest that the relationship between ASA and VSA, and the associated hydraulic force, should be considered when characterizing diastolic function and dysfunction.

Aortic stiffening precedes onset of heart failure with preserved ejection fraction in patients with asymptomatic diastolic dysfunction

Background

Identifying which patients with diastolic dysfunction will progress to heart failure with preserved ejection fraction (HFpEF) remains challenging. The goal of this study is to determine whether increased vascular stiffness as identified on 2D transthoracic echocardiography (TTE) serves as a biomarker for the development of HFpEF in patients with diastolic dysfunction.

Methods

The study design is a matched retrospective case–control study. Subjects with diastolic dysfunction were divided into two groups based on whether they had a clinical diagnosis of HFpEF. The two groups were matched based on age, gender, race and body surface area, resulting in 77 matched pairs (n = 154). Data from the first TTE that documented diastolic dysfunction prior to the development of HFpEF was extracted along with baseline demographic and clinical data. Indices of vascular stiffness were measured and compared. A sub-group analysis was performed to compare diabetic subjects in Group 1 (n = 43) to those in Group 2 (n = 21).

Results

Group 1 had significantly decreased aortic distensibility as measured on the initial TTE when compared to Group 2 (1.9 ± 1.0 vs. 2.8 ± 1.8 cm²dyne⁻¹10⁻³, p = 0.01). In the diabetic subset, Group 1 had significantly less aortic strain (6.9 ± 3.3 vs. 9.7 ± 5.6%, p = 0.02) and aortic distensibility (1.8 ± 1.0 vs. 3.5 ± 2.6 cm²dyne⁻¹10⁻³, p = 0.02) compared to Group 2. Other indices of vascular stiffness did not differ significantly between groups.

Conclusions

This study demonstrates that increased proximal aortic stiffness is associated with the development of HFpEF in patients with asymptomatic diastolic dysfunction. Larger prospective studies are needed to further investigate this relationship.