Stress-shortening relations and myocardial blood flow in compensated and failing canine hearts with pressure-overload hypertrophy

Large animal models of pressure overload-induced cardiac left ventricular hypertrophy to study remodelling of the human heart with aortic stenosis

Pathologic cardiac hypertrophy is a common consequence of many cardiovascular diseases, including aortic stenosis (AS). AS is known to increase the pressure load of the left ventricle, causing a compensative response of the cardiac muscle, which progressively will lead to dilation and heart failure. At a cellular level, this corresponds to a considerable increase in the size of cardiomyocytes, known as cardiomyocyte hypertrophy, while their proliferation capacity is attenuated upon the first developmental stages. Cardiomyocytes, in order to cope with the increased workload (overload), suffer alterations in their morphology, nuclear content, energy metabolism, intracellular homeostatic mechanisms, contractile activity, and cell death mechanisms. Moreover, modifications in the cardiomyocyte niche, involving inflammation, immune infiltration, fibrosis, and angiogenesis, contribute to the subsequent events of a pathologic hypertrophic response. Considering the emerging need for a better understanding of the condition and treatment improvement, as the only available treatment option of AS consists of surgical interventions at a late stage of the disease, when the cardiac muscle state is irreversible, large animal models have been developed to mimic the human condition, to the greatest extend. Smaller animal models lack physiological, cellular and molecular mechanisms that sufficiently resemblance humans and in vitro techniques yet fail to provide adequate complexity. Animals, such as the ferret (Mustello purtorius furo), lapine (rabbit, Oryctolagus cunigulus), feline (cat, Felis catus), canine (dog, Canis lupus familiaris), ovine (sheep, Ovis aries), and porcine (pig, Sus scrofa), have contributed to research by elucidating implicated cellular and molecular mechanisms of the condition. Essential discoveries of each model are reported and discussed briefly in this review. Results of large animal experimentation could further be interpreted aiming at prevention of the disease progress or, alternatively, at regression of the implicated pathologic mechanisms to a physiologic state. This review summarizes the important aspects of the pathophysiology of LV hypertrophy and the applied surgical large animal models that currently better mimic the condition.

Peak systolic myocardial velocity in patients undergoing surgical aortic valve replacement for severe aortic stenosis: prognostic value and natural course

Myocardial systolic longitudinal function has been known to decrease in patients with severe aortic stenosis (AS). Preoperative peak systolic myocardial velocity at the septal mitral valve annulus (S'), measured using Doppler tissue imaging, was used as an indicator for myocardial systolic longitudinal function. The prognostic value and natural course of S' after surgical aortic valve replacement for severe AS have not been elucidated. This retrospective observational study included patients from January 2006 to December 2018. The patients were divided to 2 groups (pre-S'_HIGH vs. pre-S'_LOW) with a cut-off 5.4 cm/s of preoperative S' (pre-S') that was identified by restricted cubic spline curve. The primary outcome was postoperative long-term all-cause mortality. Nine hundred and five patients were analyzed. All-cause mortality rate at the median follow-up period of 5.2 years was 12% in pre-S'_LOW and 8% in pre-S'_HIGH. Multivariate analysis showed that pre-S'_LOW was associated with an increased all-cause mortality (hazard ratio, 1.60; 95% confidence interval, 1.04-2.48; P = 0.032). Significantly different trajectories of postoperative S' (post-S') were found between two groups (P < 0.001 for difference): In pre-S'_LOW, post-S' increased within 6 months after surgery, and gradually decreased over time, whereas it slowly decreased up to 5 years after surgery and then reached a plateau in pre-S'_HIGH. The difference in pre-S' level maintained over time, and remained consistent in the adjusted analysis. Pre-S' < 5.4 cm/s was found to be associated with an increased long-term all-cause mortality. In addition, the trajectories for post-S' were different according to pre-S', which remained after adjustment.

Effect of food intake on echocardiographic measurements in healthy elderly

OBJECTIVE

This study evaluates whether food intake affects systolic and diastolic echocardiographic measurements in healthy seniors.

METHODS

Thirty healthy subjects 65-70 years of age were investigated with echocardiography, at fasting and then 30, 90, and 180 min after a meal.

RESULTS

After 30 min the biggest changes were seen in left ventricular wall stress and myocardial performance index with a decrease of 45% and 33%, respectively, compared to fasting values. Significant (p < .05) increases also were seen in left ventricular stroke volume, left ventricular cardiac output, left ventricular cardiac index, left ventricular outflow velocity-time integral, peak of early diastolic (E) and late diastolic (A) mitral flow velocities, the E/A ratio, pulsed tissue Doppler peak systolic (s') and early (e') and late (a') diastolic velocities, pulmonary vein peak velocities in systole (S) and diastole (D), mitral annular plane systolic excursion (MAPSE), tricuspid annular plane systolic excursion (TAPSE), and global longitudinal strain (GLS) (increases ranging 6%-19%). After 90 min there remained a decrease in wall stress and myocardial performance index of 31% and 17%, respectively, and smaller, but still significant, changes could be seen in left ventricular stroke volume, left ventricular outflow velocity-time integral, MAPSE (lateral), TAPSE, GLS, and a few pulsed tissue Doppler peak systolic velocities and late diastolic velocities. An increase also could be seen in deceleration time of E-wave (DT). After 180 min, all variables except DT were back at baseline or below. No significant changes were seen in S/D ratio, lateral early diastolic velocity (e' lateral) and E/e'ratio.

CONCLUSIONS

This study shows that food intake affects commonly used echocardiographic parameters, both systolic and diastolic, in healthy seniors. With a few exceptions, the changes seen in the older population were less pronounced than previous studies in younger subjects.

Impaired Left Ventricular Circumferential Midwall Systolic Performance Appears Linked to Depressed Preload, but Not Intrinsic Contractile Dysfunction or Excessive Afterload, in Paradoxical Low-Flow/Low-Gradient Severe Aortic Stenosis

Paradoxical low-flow/low-gradient aortic stenosis (P-LFLG-AS) occurs in about one-third of patients with severe AS and preserved left ventricular (LV) ejection fraction (EF). Our aim was to differentiate between altered LV loading conditions and contractility as determinants of subtle LV systolic dysfunction in P-LFLG-AS. We retrospectively analyzed medical records of patients with isolated severe degenerative AS and preserved EF (30 subjects with P-LFLG-AS and 30 patients with normal-flow/high-gradient severe AS (NFHG-AS)), without relevant coexistent diseases (e.g., diabetes, coronary artery disease and chronic kidney disease) or any abnormalities which could account for a low-flow state. Patients with P-LFLG-AS and NFHG-AS did not differ in aortic valve area index and most clinical characteristics. Compared to NFHG-AS, subjects with P-LFLG-AS exhibited smaller LV end-diastolic diameter (LVd) (44 ± 5 vs. 54 ± 5 mm, p < 0.001) (consistent with lower LV preload) with pronounced concentric remodeling, higher valvulo-arterial impedance (3.8 ± 1.1 vs. 2.2 ± 0.5 mmHg per mL/m2, p < 0.001) and diminished systemic arterial compliance (0.45 ± 0.11 vs. 0.76 ± 0.23 mL/m2 per mmHg, p < 0.001), while circumferential end-systolic LV midwall stress (cESS), an estimate of afterload at the LV level, was similar in P-LFLG-AS and NFHG-AS (175 ± 83 vs. 198 ± 69 hPa, p = 0.3). LV midwall fractional shortening (mwFS) was depressed in P-LFLG-AS vs. NFHG-AS (12.3 ± 3.5 vs. 14.7 ± 2.9%, p = 0.006) despite similar EF (61 ± 6 vs. 59 ± 8%, p = 0.4). By multiple regression, the presence of P-LFLG-AS remained a significant predictor of lower mwFS compared to NFHG-AS upon adjustment for cESS (β ± SEM: −2.35 ± 0.67, p < 0.001); however, the significance was lost after further correction for LVd (β = −1.10 ± 0.85, p = 0.21). In conclusion, the association of P-LFLG-AS with a lower cESS-adjusted mwFS, an index of afterload-corrected LV circumferential systolic function at the midwall level, appears secondary to a smaller LV end-diastolic cavity size according to the Frank−Starling law. Thus, low LV preload, not intrinsic contractile dysfunction or excessive afterload, may account for impaired LV circumferential midwall systolic performance in P-LFLG-AS.

Coronary blood flow in heart failure: cause, consequence and bystander

Heart failure is a clinical syndrome where cardiac output is not sufficient to sustain adequate perfusion and normal bodily functions, initially during exercise and in more severe forms also at rest. The two most frequent forms are heart failure of ischemic origin and of non-ischemic origin. In heart failure of ischemic origin, reduced coronary blood flow is causal to cardiac contractile dysfunction, and this is true for stunned and hibernating myocardium, coronary microembolization, myocardial infarction and post-infarct remodeling, possibly also for the takotsubo syndrome. The most frequent form of non-ischemic heart failure is dilated cardiomyopathy, caused by genetic mutations, myocarditis, toxic agents or sustained tachyarrhythmias, where alterations in coronary blood flow result from and contribute to cardiac contractile dysfunction. Hypertrophic cardiomyopathy is caused by genetic mutations but can also result from increased pressure and volume overload (hypertension, valve disease). Heart failure with preserved ejection fraction is characterized by pronounced coronary microvascular dysfunction, the causal contribution of which is however not clear. The present review characterizes the alterations of coronary blood flow which are causes or consequences of heart failure in its different manifestations. Apart from any potentially accompanying coronary atherosclerosis, all heart failure entities share common features of impaired coronary blood flow, but to a different extent: enhanced extravascular compression, impaired nitric oxide-mediated, endothelium-dependent vasodilation and enhanced vasoconstriction to mediators of neurohumoral activation. Impaired coronary blood flow contributes to the progression of heart failure and is thus a valid target for established and novel treatment regimens.

Large animal models of heart failure with preserved ejection fraction

Heart failure with preserved ejection fraction (HFpEF) is characterized by diastolic dysfunction and multiple comorbidities. The number of patients is continuously increasing, with no improvement in its unfavorable prognosis, and there is a strong need for novel treatments. New devices and drugs are difficult to assess at the translational preclinical step due to the lack of high-fidelity large animal models of HFpEF. In this review, we describe the summary of historical and evolving techniques for developing large animal models. The representative methods are pressure overload models, including (1) aortic banding, (2) aortic stent, (3) renal hypertension, and (4) mineralocorticoid-induced hypertension. Diet-induced metabolic syndromes are also used. A new technique with an inflatable balloon inside the left ventricle can be used during acute/chronic in vivo surgeries to simulate HFpEF-like hemodynamics for pump-based therapies. Canines and porcine are most widely used, but other non-rodent animals (sheep, non-human primates, felines, or calves) have been used. Feline models present the most well-simulated HFpEF pathology, but small size is a concern, and the information is still very limited. The rapid and reliable establishment of large animal models for HFpEF, and novel methodology based on the past experimental attempts with large animals, are needed.

Forward Left Ventricular Ejection Fraction as a Predictor of Postoperative Left Ventricular Dysfunction in Patients with Degenerative Mitral Regurgitation

Background: Left ventricular dysfunction (LVD) can occur immediately after mitral valve repair (MVr) for degenerative mitral regurgitation (DMR) in some patients with normal preoperative left ventricular ejection fraction (LVEF). This study investigated whether forward LVEF, calculated as left ventricular outflow tract stroke volume divided by left ventricular end-diastolic volume, could predict LVD immediately after MVr in patients with DMR and normal LVEF. Methods: Echocardiographic and clinical data were retrospectively evaluated in 234 patients with DMR ≥ moderate and preoperative LVEF ≥ 60%. LVD and non-LVD were defined as LVEF < 50% and ≥50%, respectively, as measured by echocardiography after MVr and before discharge. Results: Of the 234 patients, 52 (22.2%) developed LVD at median three days (interquartile range: 3–4 days). Preoperative forward LVEF in the LVD and non-LVD groups were 24.0% (18.9–29.5%) and 33.2% (26.4–39.4%), respectively (p < 0.001). Receiver operating characteristic (ROC) analyses showed that forward LVEF was predictive of LVD, with an area under the ROC curve of 0.79 (95% confidence interval: 0.73–0.86), and an optimal cut-off was 31.8% (sensitivity: 88.5%, specificity: 58.2%, positive predictive value: 37.7%, and negative predictive value: 94.6%). Preoperative forward LVEF significantly correlated with preoperative mitral regurgitant volume (correlation coefficient [CC] = −0.86, p < 0.001) and regurgitant fraction (CC = −0.98, p < 0.001), but not with preoperative LVEF (CC = 0.112, p = 0.088). Conclusion: Preoperative forward LVEF could be useful in predicting postoperative LVD immediately after MVr in patients with DMR and normal LVEF, with an optimal cut-off of 31.8%.

Cardiac hypertrophic risk markers of left ventricle and left atrium in chronic heart failure due to aortic and mitral valve disease

BACKGROUND

Chronic valvular heart disease leads to systolic dysfunction and left atrial enlargement that ultimately results in heart failure.

PURPOSE

To investigate prognostic importance of Echocardiography and plasma natriuretic peptide levels that increase as a compensatory response and can be used as predictive markers for cardiac hypertrophy.

MATERIAL AND METHODS

The patients were divided into three groups: 51 with left ventricle hypertrophy due to aortic valve disease; 126 with left atrial enlargement due to mitral valve dysfunction; and 76 with both conditions. Atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP) plasma levels were measured in all three respective groups showing dilated cardiomyopathy.

RESULTS

The mean left ventricular end-diastolic dimension at 64.3 ± 1.6 mm (P < 0.00) and left atrial dimension at 58.3 ± 3.7 mm (P < 0.00) were significantly high. However, patients with both conditions showed significantly high values for left ventricular end-diastolic dimension (63.3 ± 3 mm, P < 0.00) and left atrial dimension (54.9 ± 4 mm, P < 0.00) when compared with controls. A significant positive correlation was found between plasma natriuretic peptides levels and dilated cardiomyopathy. The mean values of ANP were 173 ± 46.6 pg/mL (P < 0.00), 140.4 ± 42.4 pg/mL (P < 0.00), and 295.1 ± 67.5 pg/mL (P < 0.00), significantly high in all three respective disease groups. The levels of BNP were also significantly high at 189 ± 44.5 pg/mL (P < 0.00), 166.6 ± 36.6 pg/mL (P < 0.00), and 323 ± 69.1 pg/mL (P < 0.00) in the disease groups with left ventricular hypertrophy, left atrial enlargement, and the disease group showing both characteristics, respectively.

CONCLUSION

Significant positive associations were found between left ventricle hypertrophy and left atrial enlargement with ANP and BNP.

The canine chronic atrioventricular block model in cardiovascular preclinical drug research

Ventricular cardiac arrhythmia is a life threating condition arising from abnormal functioning of many factors in concert. Animal models mirroring human electrophysiology are essential to predict and understand the rare pro- and anti-arrhythmic effects of drugs. This is very well accomplished by the canine chronic atrioventricular block (CAVB) model. Here we summarize canine models for cardiovascular research, and describe the development of the CAVB model from its beginning. Understanding of the structural, contractile and electrical remodelling processes following atrioventricular (AV) block provides insight in the many factors contributing to drug-induced arrhythmia. We also review all safety pharmacology studies, efficacy and mechanistic studies on anti-arrhythmic drugs in CAVB dogs. Finally, we compare pros and cons with other in vivo preclinical animal models. In view of the tremendous amount of data obtained over the last 100 years from the CAVB dog model, it can be considered as man's best friend in preclinical drug research.

Left ventricular myocardial oxygen demand and subclinical dysfunction in patients with severe obesity referred for bariatric surgery

BACKGROUND AND AIMS

Increased myocardial oxygen (O₂) demand carries higher cardiovascular risk in hypertension. We hypothesized that myocardial O₂ demand is increased in severe obesity and linked to early left ventricular (LV) dysfunction.

METHODS AND RESULTS

Baseline data from 106 severely obese subjects referred for gastric bypass surgery (42 ± 11 years, 74% women, body mass index [BMI] 41.9 ± 4.8 kg/m², 32% with hypertension) in the prospective FatWest (Bariatric Surgery on the West Coast of Norway) study was used. LV systolic function was assessed by biplane ejection fraction (EF), midwall shortening (MWS) and endocardial global longitudinal strain (GLS), and LV diastolic function by mitral annular early diastolic velocity (e'). Myocardial O₂ demand was estimated from the LV mass-wall stress-heart rate product (high if > 1.62 × 10⁶/2.29 × 10⁶ g kdyne/cm² bpm in women/men). High myocardial O₂ demand was found in 33% and associated with higher BMI and high prevalence of low GLS (65%) and low MWS (63%) despite normal EF. In ROC analyses, higher myocardial O₂ demand discriminated between patients with low vs. normal MWS and GLS (area under curve 0.71 and 0.63, p < 0.05). In successive multiple regression analyses, higher myocardial O₂ demand was associated with lower LV MWS, GLS and average e', respectively, independent of age, gender, BMI, pulse pressure, diabetes mellitus, and EF (all p < 0.05).

CONCLUSION

In obese patients without known heart disease and with normal EF referred for bariatric surgery, high myocardial O₂ demand is associated with lower myocardial function whether assessed by GLS or MWS independent of confounders. CLINICALTRIALS.

GOV IDENTIFIER

NCT01533142.

Relationship between myocardial energy expenditure and postoperative ejection fraction in patients with severe mitral regurgitation

Objective:

This prospective study aimed to investigate the myocardial energy metabolism in severe mitral regurgitation (MR) and explore its effect on postoperative differentiation of ejection fraction (EF).

Methods:

A total of 85 patients with severe MR were prospectively enrolled from October 2018 to June 2019. During the study period, a total of 50 patients underwent mitral valve surgery and 49 patients were finally enrolled due to 1 missing data. Left ventricular function, circumferential end-systolic stress (cESS), and myocardial energy expenditure (MEE) were measured by transthoracic echocardiography preoperatively and 3 months after surgery. Patients were divided into 2 groups according to absolute difference of postoperative differentiation of EF.

Results:

Nine patients underwent mitral valve repair and 40 underwent prosthetic valve replacement. Patients with reduced EF had higher MEE demonstrated with cESS and MEE. Negative correlation between preoperative EF and N-terminal pro-brain natriuretic peptide (NT-proBNP), cESS, MEEs, and MEEm and positive correlation between preoperative EF and effective regurgitant orifice area were found. Complications occurred in 12 patients during hospitalization. Basal NT-proBNP, left atrium (LA), and cESS were significantly higher in postoperatively decreased EF group. Taking into consideration the covariates of multiple logistic regression analysis, LA and cESS were found to be independent predictors of EF reduction postoperatively.

Conclusion:

Higher LA and cESS are independent predictors of postoperative EF reduction. Preoperative high end-systolic stress could predict postoperative EF reduction and hence could be helpful for determining the timing of mitral valve surgery. Although MEE was higher in postoperatively decreased EF group, it did not reach statistical significance.

Large Animal Models of Heart Failure: A Translational Bridge to Clinical Success

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Preclinical large animal models play a critical and expanding role in translating basic science findings to the development and clinical approval of novel cardiovascular therapeutics.

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This state-of-the-art review outlines existing methodologies and physiological phenotypes of several HF models developed in large animals. A comprehensive list of porcine, ovine, and canine models of disease are presented, and the translational importance of these studies to clinical success is highlighted through a brief overview of recent devices approved by the FDA alongside associated clinical trials and preclinical animal reports.

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Increasing the use of large animal models of HF holds significant potential for identifying new mechanisms underlying this disease and providing valuable information regarding the safety and efficacy of new therapies, thus, improving physiological and economical translation of animal research to the successful treatment of human HF.

Preclinical large animal models of heart failure (HF) play a critical and expanding role in translating basic science findings to the development and clinical approval of novel therapeutics and devices. The complex combination of cardiovascular events and risk factors leading to HF has proved challenging for the development of new treatments for these patients. This state-of-the-art review presents historical and recent studies in porcine, ovine, and canine models of HF and outlines existing methodologies and physiological phenotypes. The translational importance of large animal studies to clinical success is also highlighted with an overview of recent devices approved by the Food and Drug Administration, together with preclinical HF animal studies used to aid both development and safety and/or efficacy testing. Increasing the use of large animal models of HF holds significant potential for identifying the novel mechanisms underlying the clinical condition and to improving physiological and economical translation of animal research to successfully treat human HF.

Better Myocardial Function in Aortic Stenosis with Low Left Ventricular Mass: A Mechanism of Protection against Heart Failure Regardless of Stenosis Severity?

About one-tenth to one-third of patients with severe aortic stenosis (AS) do not develop left ventricular hypertrophy (LVH). Intriguingly, the absence of LVH despite severe AS is associated with lower prevalence of heart failure (HF), which challenges the classical notion of LVH as a beneficial compensatory response. Notably, the few studies that have attempted to characterize AS subjects with inadequately low left ventricular (LV) mass relative to LV afterload (i-lowLVM) described better prognosis and enhanced LV performance in AS associated with i-lowLVM, but those reports were limited to severe AS. Our aim was to compare myocardial function between moderate and severe AS with i-lowLVM. We retrospectively analyzed in-hospital records of 225 clinically stable nondiabetic patients with isolated moderate or severe degenerative AS in sinus rhythm, free of coexistent diseases. Subjects with i-lowLVM were compared to those with appropriate or excessive LVM (a/e-LVM), defined on the basis of the ratio of a measured LVM to the LVM predicted from an individual hemodynamic load. Patients with i-lowLVM and a/e-LVM did not differ in aortic valve area, LV end-diastolic diameter (LVd, a measure of LV preload), and circumferential end-systolic LV wall stress (cESS), an estimate of LV afterload. Compared to a/e-LVM, patients with i-lowLVM had increased LV ejection fraction (EF) and especially higher LV midwall fractional shortening (a better index of LV myocardial function than EF in concentric LV geometry) (p < 0.001–0.01), in both moderate and severe AS. LVd and cESS were similar in the four subgroups of the study subjects, i.e., moderate AS with i-lowLVM, moderate AS with a/e-LVM, severe AS with i-lowLVM, and severe AS with a/e-LVM (p > 0.6). Among patients with i-lowLVM, LVM did not differ significantly between moderate and severe AS (p > 0.4), while in those with a/e-LVM, LVM was increased in severe versus moderate AS (p < 0.001). In conclusion, the association of the low-LVM phenotype with better myocardial contractility may already develop in moderate AS. Additionally, cESS appears to be a controlled variable, which is kept constant over AS progression irrespective of LVM category, but even when controlled (by increasing LVM), is not able to prevent deterioration of LV function. Whether improved myocardial performance contributes to favorable prognosis and the preventive effect against HF in AS without LVH, remains to be studied.

Higher left ventricular mass-wall stress-heart rate product and outcome in aortic valve stenosis

OBJECTIVE

Whether increased myocardial oxygen demand could help explain the association of left ventricular (LV) hypertrophy with higher adverse event rate in patients with aortic valve stenosis (AS) is unknown.

METHODS

Data from 1522 patients with asymptomatic mostly moderate AS participating in the Simvastatin-Ezetimibe in AS study followed for a median of 4.3 years was used. High LV mass-wall stress-heart rate product was identified as >upper 95% CI limit in normal subjects. The association of higher LV mass-wall stress-heart rate product with major cardiovascular (CV) events, combined CV death and hospitalised heart failure and all-cause mortality was tested in Cox regression analyses, and reported as HR and 95% CI.

RESULTS

High LV mass-wall stress-heart rate product was found in 19% at baseline, and associated with male sex, higher body mass index, hypertension, LV hypertrophy, more severe AS and lower LV ejection fraction (all p<0.01). Adjusting for these confounders in time-varying Cox regression analysis, 1 SD higher LV mass-wall stress-heart rate product was associated with higher HR of major CV events (HR 1.16(95% CI 1.06 to 1.29)), combined CV death and hospitalised heart failure (HR 1.29(95% CI 1.09 to 1.54)) and all-cause mortality (HR 1.34(95% CI 1.13 to 1.58), all p<0.01).

CONCLUSION

In patients with initially mild-moderate AS, higher LV mass-wall stress-heart rate product was associated with higher mortality and heart failure hospitalisation. Our results suggest that higher myocardial oxygen demand is contributing to the higher adverse event rate reported in AS patients with LV hypertrophy.

TRIAL REGISTRATION NUMBER

NCT000092677;Post-results.

Left Ventricular Contractility and Wall Stress in Patients With Aortic Stenosis With Preserved or Reduced Ejection Fraction

OBJECTIVES

This study sought to determine the prevalence of reduced contractility and uncompensated wall stress in patients with aortic stenosis (AS) with preserved or reduced left ventricular ejection fraction (LVEF) and their impact on survival.

BACKGROUND

LVEF in AS is determined not only by contractility but also by loading conditions.

METHODS

Patients with first diagnosis (time 0) of severe AS (aortic valve area [AVA]≤1 cm²) with prior echo study (-3±1 years) were identified. Contractility was evaluated by plotting midwall fractional shortening (mFS) against circumferential end-systolic wall stress (cESS), stratified by LVEF of 60% at time 0. The temporal changes (from -3 years to time 0) and prognostic value of LVEF, contractility, and wall stress were assessed.

RESULTS

Of 445 patients, 290 (65%) had LVEF ≥60% (median: 66% [interquartile range {IQR}: 63% to 69%]) and 155 patients (35%) had LVEF <60% (median: 47% [IQR: 34% to 55%]). Median AVA was 1.27 cm² (IQR: 1.13 to 1.43 cm²) at -3 years and 0.90 cm² (IQR: 0.83 to 0.96 cm²) at time 0. Decreased contractility was already present at -3 years (49 [17%] vs. 59 [38%]; LVEF ≥60% vs. <60%; p < 0.001) and became more prevalent at time 0 (69 [24%] vs. 106 [68%]; p < 0.001). Overall, wall stress was well controlled in both groups at -3 years (1 [0%] vs. 12 [8%]; p < 0.001) but deteriorated over time in patients with LVEF <60% (time 0: 0 [0%] vs. 26 [17%]; p < 0.001). During a median follow-up of 3.4 years, LVEF <60%, decreased contractility and high wall stress were associated with worse survival (p < 0.01 for all). Decreased contractility remained incremental to LVEF in patients with LVEF ≥60% (p < 0.01), but less so when LVEF was <60% (p = 0.11).

CONCLUSIONS

In patients with severe AS, LVEF <60% is associated with a poor prognosis, being linked with decreased contractility and/or high wall stress. Decreased contractility is also present in a subset of patients with LVEF ≥60% and provides incremental prognostic value. These abnormalities already exist before AVA reaches 1.0 cm².

Predicting the Time Course of Ventricular Dilation and Thickening Using a Rapid Compartmental Model

The ability to predict long-term growth and remodeling of the heart in individual patients could have important clinical implications, but the time to customize and run current models makes them impractical for routine clinical use. Therefore, we adapted a published growth relation for use in a compartmental model of the left ventricle (LV). The model was coupled to a circuit model of the circulation to simulate hemodynamic overload in dogs. We automatically tuned control and acute model parameters based on experimentally reported hemodynamic data and fit growth parameters to changes in LV dimensions from two experimental overload studies (one pressure, one volume). The fitted model successfully predicted the reported time course of LV dilation and thickening not only in independent studies of pressure and volume overload but also following myocardial infarction. Implemented in MATLAB on a desktop PC, the model required just 6 min to simulate 3 months of growth.

Echocardiographic aortic valve calcification and outcomes in women and men with aortic stenosis

Objective

Sex differences in risk factors of aortic valve calcification (AVC) by echocardiography have not been reported from a large prospective study in aortic stenosis (AS).

Methods

AVC was assessed using a prognostically validated visual score and grouped into none/mild or moderate/severe AVC in 1725 men and women with asymptomatic AS in the Simvastatin Ezetimibe in Aortic Stenosis study. The severity of AS was assessed by the energy loss index (ELI) taking pressure recovery in the aortic root into account.

Results

More men than women had moderate/severe AVC at baseline despite less severe AS by ELI (p<0.01). Moderate/severe AVC at baseline was independently associated with lower aortic compliance and more severe AS in both sexes, and with increased high-sensitive C reactive protein (hs-CRP) only in men (all p<0.01). In Cox regression analyses, moderate/severe AVC at baseline was associated with a 2.5-fold (95% CI 1.64 to 3.80) higher hazard rate of major cardiovascular events in women, and a 2.2-fold higher hazard rate in men (95% CI 1.54 to 3.17) (both p<0.001), after adjustment for age, hypertension, study treatment, aortic compliance, left ventricular (LV) mass and systolic function, AS severity and hs-CRP. Moderate/severe AVC at baseline also predicted a 1.8-fold higher hazard rate of all-cause mortality in men (95% CI 1.04 to 3.06, p<0.05) independent of age, AS severity, LV mass and aortic compliance, but not in women.

Conclusion

In conclusion, AVC scored by echocardiography has sex-specific characteristics in AS. Moderate/severe AVC is associated with higher cardiovascular morbidity in both sexes, and with higher all-cause mortality in men.

Trial registration number

ClinicalTrials.gov identifier: NCT00092677

Favorable Pulse Wave Augmentation Indices and Left Ventricular Diastolic Profile in β-Thalassemia Minor

β-Thalassemia minor (β-Τm) is associated with rheological and biochemical alterations that can affect cardiovascular function. We aimed to evaluate the elastic arterial properties and the pulse wave augmentation indices in a population of patients with β-Τm. Seventy-five individuals with β-Τm (age 55.5 [42.75-65.25], women 48%) and 127 controls (age 57 years [48-63], women 55.1%) underwent comprehensive echocardiographic evaluation and applanation tonometry of the radial and femoral artery. Pulse wave analysis revealed that augmentation pressure, augmentation index (AIx), and heart rate-corrected AIx were significantly lower (median [interquartile range]: 8.75 [4.625-13] vs 11 [6.5-14.5], P = .017; 26.5 [17.5-33.375] vs 30.5 [20.75-37.5], P = .014; and 22.25 [15.125-29.5] vs 27 [20.5-33], P = .008, respectively) in the β-Τm group compared to controls. The left atrial active emptying volume was significantly lower and the isovolumic relaxation time was shorter in the β-Τm group compared to the control group (10.2 [7.4-14.4] vs 12.0 [8.6-15.8], P = .040 and 78 [70-90] vs 90 [70-104], P = .034, respectively). β-Thalassemia minor is associated with favorable pulse wave augmentation indices and left ventricular diastolic function profile in asymptomatic individuals with cardiovascular risk factors.

Left Ventricular Function Assessed by One-Point Carotid Wave Intensity in Newly Diagnosed Untreated Hypertensive Patients

OBJECTIVES

To investigate whether newly diagnosed untreated hypertensive patients show higher left ventricular (LV) contractility, as assessed by traditional echocardiographic indices and carotid wave intensity (WI) parameters, including amplitude of the peak during early (W₁ ) and late systole (W₂ ).

METHODS

A total of 145 untreated hypertensive patients were compared with 145 age- and sex-matched normotensive subjects. They underwent comprehensive echocardiography and WI analysis. WI analysis was performed at the level of the common carotid artery. The diameter changes were the difference between the displacement of the anterior and posterior walls, with the cursors set to track the media-adventitia boundaries 2 cm proximal to the carotid bulb and calibrated by systolic and diastolic BP. Peak acceleration was derived from blood flow velocity measured by Doppler sonography with the range-gate positioned at the center of the vessel diameter. WI was based on the calculation of (dP/dt)×(dU/dt), where dP/dt and dU/dt were the derivatives of BP (P) and velocity (U) with respect to time. One-point pulse wave velocity (PWVβ) and the interval between the R wave on ECG and the first peak of WI (R-W₁ ), using a high definition echo-tracking system implemented in the ultrasound machine (Aloka), were also derived.

RESULTS

After adjustment for body weight, heart rate, and physical activity, the two groups had similar general characteristics and diastolic function. However, hypertensives showed significantly higher LV mass, LV ejection fraction (LVEF), circumferential and LV end-systolic stress, and one-point PWV as well as W₁ (13.646 ± 7.368 vs 9.308 ± 4.675 mmHg m/s³ , P =.001) and W₂ (4.289 ± 2.017 vs 2.995 ± 1.868 mmHg m/s³ , P =.001). Hypertensives were divided into tertiles according to LVEF: W₁ (11.934 ± 5.836 vs 11.576 ± 5.857 vs 17.227 ± 8.889 mmHg m/s³ , P <.0001) was higher in the highest LVEF tertile along with relative wall thickness, midwall fractional shortening, endocardial fractional shortening, and R-W₁ .

CONCLUSIONS

Newly diagnosed hypertensives show increased LVM and LV contractility, including carotid WI parameters and R-W₁ values, as compared with normotensive subjects, but no differences in LV diastolic function.

Myocardial Performance Index in Childhood Onset Essential Hypertension and White Coat Hypertension

BACKGROUND

As a global measure of ventricular systolic and diastolic function, the myocardial performance index (MPI) can be an early indicator of hypertensive cardiomyopathy in children with essential hypertension (EH).

METHODS

Children with untreated newly diagnosed EH and white coat hypertension (WCH) by a 24-hour ambulatory blood pressure monitoring (ABPM), both groups without any identifiable etiology for the hypertension, were enrolled for the study. Echocardiograms and vascular ultrasounds for carotid artery intimal medial thickness were performed on all children prior to therapy. Diastolic function (peak E and A velocities, E/A ratio, isovolumic relaxation time, and deceleration times) and MPI were evaluated by simultaneous transmitral and transaortic spectral Doppler flow velocities. Systolic function was evaluated by shortening fraction and ejection fraction.

RESULTS

A cohort of 66 children (24 with EH, 42 with WCH, males 61%, median age of 13 years, range 10-17 years) were enrolled in the study. The demographic, anthropometric, laboratory tests, vascular ultrasound, and conventional echocardiographic parameters were similar between the 2 groups. There was a very small difference in MPI between the EH and WCH children (0.28 SD: 0.07 vs. 0.31 SD: 0.08, P = 0.045). However, in EH children, MPI increased by 0.14 units for every 10 unit increase in mean ABPM systolic BP (95% confidence interval: 0.03-0.25).

CONCLUSIONS

We found the increasing MPI was associated with increasing 24-hour mean systolic BP in children with EH. Therefore, MPI may have utility as a single, quick, noninvasive method of detection and tracking of subclinical hypertensive heart disease.

Coronary slow flow phenomenon: Not only low in flow rate but also in myocardial energy expenditure

BACKGROUND AND AIM

Coronary slow flow phenomenon (CSFP) is a miscellaneous clinical entity leading to angina-like symptoms, and electrocardiographic and scintigraphic evidence of ischemia. The impact of this syndrome on myocardial performance has not been comprehensively evaluated. In this study, we sought to evaluate the myocardial energy expenditure (MEE) in patients with CSFP and its relationship with exercise capacity.

METHODS AND RESULTS

A total of 64 patients (64.1% male, mean age 53.2 ± 10.3 years) with CSFP and 64 patients (60.9% male, mean age 52.2 ± 10.9 years) with normal coronary artery as control group were included. MEE was calculated by a validated formula that uses transthoracic echocardiography (TTE) parameters, including left ventricular circumferential end-systolic stress, stroke volume, and ejection time CSFP patients had significantly lower MEE (0.79 cal/systole ± 0.15 vs. 0.91 cal/systole ± 0.09, p < 0.001). In correlation analysis, MEE had a significant negative correlation with mean corrected TIMI frame count (mTFC) (β = -0.523; p < 0.001) and positive correlations with metabolic equivalents (METs) (β = 0.560; p < 0.001), rate pressure product (β = 0.649; p < 0.001), and exercise duration (β = 0.408; p < 0.001). At multivariate analysis, MEE was demonstrated as an independent predictor of CSFP (OR 1.863, CI 95% 1.485-2.338 p < 0.001).

CONCLUSION

Myocardial energy consumption, as a calculation obtained from TTE parameters, was reduced in patients with CSFP, and it had a significant relationship with exercise capacity. Considering its significant correlation with exercise capacity, myocardial energy consumption seemed to use evaluation of myocardial performance and functional status in another cardiovascular disease.

Compensatory increase of left atrial external work to left ventricular dysfunction caused by afterload increase

Afterload mismatch can cause acute decompensation leading to an occurrence of acute heart failure. We investigated how the left atrium (LA) and left ventricle (LV) react to acute increases in afterload using speckle tracking echocardiography (STE). LA strain and volume were obtained by STE in 10 dogs during banding of descending aorta (AoB). Simultaneously, LA pressure was measured by a micromanometer-tipped catheter. LA peak negative strain during LA contraction, strain change during LA relaxation (early reservoir strain), and that during LA dilatation (late reservoir strain) were obtained from LA longitudinal strain-volume curves. From pressure-strain curves, the areas of A-loop and V-loops were computed as the work during active contraction and relaxation (A-work) and that during passive filling and emptying (V-work). AoB increased LV systolic pressure (105 ± 15 vs. 163 ± 12 mmHg, P < 0.01) and mean LA pressure (3.8 ± 1.2 vs. 7.1 ± 2.0 mmHg, P < 0.01). LV global circumferential strain decreased (−18.8 ± 3.5 vs. −13.2 ± 3.5%, P < 0.01), but LV stroke volume was maintained (8.4 ± 2.3 vs. 9.6 ± 3.6 ml). LA peak negative strain (−2.9 ± 2.3 vs. −9.8 ± 4.0%, P < 0.01) and early reservoir strain (4.5 ± 2.1 vs. 7.7 ± 2.4%, P < 0.05) increased by AoB, but late reservoir strain did not change (8.9 ± 3.4 vs. 6.1 ± 3.4%). A-work significantly increased (3.2 ± 2.0 vs. 19.2 ± 15.1 mmHg %, P < 0.01), whereas V-work did not change (13.3 ± 7.1 vs. 13.1 ± 7.7 mmHg %). In conclusion, LA external work during active contraction and relaxation increased as compensation for LV dysfunction during aortic banding. Atrial dysfunction may lead failure of this mechanism and hemodynamic decompensation.

Prognostic value of depressed midwall systolic function in cardiac light-chain amyloidosis

BACKGROUND

Cardiac amyloidosis represents an archetypal form of restrictive heart disease, characterized by profound diastolic dysfunction. As ejection fraction is preserved until the late stage of the disease, the majority of patients do fulfill the definition of diastolic heart failure, that is, heart failure with preserved ejection fraction (HFpEF). In another clinical model of HFpEF, that is, pressure-overload hypertrophy, depressed midwall fractional shortening (mFS) has been shown to be a powerful prognostic factor.

OBJECTIVE AND METHODS

To assess the potential prognostic role of mFS in cardiac light-chain amyloidosis with preserved ejection fraction, we enrolled 221 consecutive untreated patients, in whom a first diagnosis of cardiac light-chain amyloidosis was concluded between 2008 and 2010. HFpEF was present in 181 patients. Patients in whom cardiac involvement was excluded served as controls (n = 121). Prognosis was assessed after a median follow-up of 561 days.

RESULTS

When compared with light-chain amyloidosis patients without myocardial involvement, cardiac light-chain amyloidosis was characterized by increased wall thickness (P <0.001), reduced end-diastolic left ventricular volumes (P <0.001), and diastolic dysfunction (P <0.001). In patients with preserved ejection fraction, mFS was markedly depressed [10.6% (8.7-13.5) vs. 17.8% (15.9-19.5) P <0.001]. At multivariable analysis, mFS, troponin I, and NT-pro-brain natriuretic peptide were the only significant prognostic determinants (P <0.001), whereas other indices of diastolic (E/E' ratio, transmitral and pulmonary vein flow velocities) and systolic function (tissue Doppler systolic indices, ejection fraction), or the presence/absence of congestive heart failure did not enter the model.

CONCLUSION

In cardiac light-chain amyloidosis with normal ejection fraction, depressed circumferential mFS, a marker of myocardial contractile dysfunction, is a powerful predictor of survival.

How does stress possibly affect cardiac remodeling?

The aim of this study was to evaluate the predictive value of adrenocorticotropic hormone (ACTH), cortisol and ACTH receptor polymorphism (ACTHRP) for left ventricular (LV) remodeling. Thirty-six elite male athletes, as chronic stress adaptation models, and twenty sedentary age and sex-mached subjects emabarked on standard and tissue Doppler echocardiography to assess cardiac parameters at rest. They performed maximal cardiopulmonary test, which was used as an acute stress model. ACTH and cortisol were measured at rest (10min before test), at beginning, at maximal effort, at 3rd min of recovery, using radioimmunometric and radioimmunoassey techniques, respectively. Promoter region of ACTHR gene (18p11.2) was analysed from blood samples using reverse polymerization reaction with the analysis of restriction fragment length polimorphisam by SacI restriction enzyme. Normal genotype was CTC/CTC, heterozygot for ACTHRP CTC/CCC and homozygot CCC/CCC. In all participants, ACTH and cortisol increased during acute stress, whereas in recovery ACTH increased and cortisol remained unchanged. 49/56 examiners manifested CTC/CTC, 7/56 CTC/CCC and 0/56 CCC/CCC. There was no difference in ACTHRP frequency between groups (χ(1)(2)=0.178, p=0.67). LV mass (LVM) and LV end-diastolic volume (LVVd) were higher in athletes than in controls (p<0.01) and lower in CTC/CTC than in CTC/CCC genotype (219.43±46.59(SD)g vs. 276.34±48.86(SD)g, p=0.004; 141.24±24.46(SD)ml vs. 175.29±37.07(SD)ml, p=0.002; respectively). In all participants, predictors of LVM and LVVd were ACTH at rest (B=-1.00,-0.44; β=-0.30,-0.31; p=0.026,0.012, respectively) and ACTHRP (B=56.63,34; β=0.37,0.40; p=0.003,0.001, respectively). These results demonstrate that ACTH and ACTHRP strongly predict cardiac morphology suggesting possible regulatory role of stress system activity and sensitivity in cardiac remodeling.

Increased short-term blood pressure variability is associated with early left ventricular systolic dysfunction in newly diagnosed untreated hypertensive patients

BACKGROUND AND AIM

Twenty-four-hour blood pressure (BP) variability, by ambulatory BP monitoring (ABPM), has been related to left ventricular hypertrophy, independent of mean BP values. We tested the hypothesis that short-term BP variability (BPV) is also related to subclinical left ventricular systolic dysfunction.

METHODS

We assessed 24-h SBP and DBP variabilities, quantified as standard deviation (SD) of daytime (awake) BP values and as weighted SD of 24-h BP (24-h-weighted BPV), in 309 recently (<6 months) diagnosed, prospectively recruited, and untreated hypertensive patients. Patients were included only if with normal (≥55%) left ventricular ejection fraction (LVEF). Left ventricular systolic function was assessed by echocardiography measuring midwall fractional shortening (MFS), circumferential end-systolic stress (cESS), MFS/cESS, peak systolic wall stress, left ventricular fractional shortening (LVFS), and LVEF.

RESULTS

At multivariate analysis, awake and 24-h-weighted SBP variabilities (directly, P = 0.038 and P = 0.002, respectively) as well as relative wall thickness (RWT) (inversely, P = 0.001) were significantly related to cESS. Awake and 24-h SBP average values (inversely, P = 0.011 and P = 0.002, respectively), awake and 24-h-weighted SBP variabilities (inversely, P = 0.017 and P = 0.024, respectively), and RWT (directly, P = 0.001) were all significantly related to MFS/cESS. Finally, awake and 24-h average SBP (directly, P = 0.01 for both), awake and 24-h-weighted SBP variability (directly, P = 0.001 and P = 0.032, respectively), and RWT (inversely, P = 0.001) were all significantly and independently related to peak systolic wall stress.

CONCLUSION

In newly diagnosed never-treated hypertensive patients, in the absence of LVEF changes and independent of left ventricular mass index, higher awake, or 24-h-weighted short-term SBP variabilities are associated with early depressed left ventricular systolic function.

Effect of food intake on left ventricular wall stress

Objective

Left ventricular wall stress has been investigated in a variety of populations, but the effect of food intake has not been evaluated. We assessed whether left ventricular wall stress is affected by food intake in healthy subjects.

Methods

Twenty-three healthy subjects aged 25.6 ± 4.5 years were investigated. Meridional end-systolic wall stress (ESS) and circumferential end-systolic wall stress (cESS) were measured before, 30 minutes after, and 110 minutes after a standardised meal.

Results

Both ESS and cESS decreased significantly (P < 0.001) from fasting values 30 minutes after the meal, and had not returned to baseline after 110 minutes. ESS decreased from 65 ± 16 kdynes/cm² (fasting) to 44 ± 12 kdynes/cm² 30 minutes after, and to 58 ± 13 kdynes/cm² 110 minutes after eating. cESS decreased from 98 ± 24 kdynes/cm² to 67 ± 18 kdynes/cm² 30 minutes after, and to 87 ± 19 kdynes/cm² 110 minutes after the meal.

Conclusion

This study shows that left ventricular wall stress is affected by food intake in healthy subjects.

Prevalence and covariates of abnormal left ventricular geometry in never-treated hypertensive patients in Tanzania

AIM. To assess prevalence, type and covariates of abnormal left ventricular (LV) geometry in untreated native Tanzanian patients with hypertension in relation to normotensive controls. METHODS. Echocardiography was performed in 161 untreated hypertensive outpatients and 80 normotensive controls at a tertiary hospital in Tanzania. Hypertensive heart disease was defined as presence of increased LV mass or relative wall thickness (RWT). RESULTS. The prevalence of hypertensive heart disease increased with the severity of hypertension and was on average 62.1% among patients and 12.5% in controls. In multivariate analyses, higher LV mass index was associated with higher systolic blood pressure (β = 0.28), body mass index (β = 0.20), peak early transmitral to medial mitral annulus velocity ratio (β = 0.16), and with lower stress-corrected midwall shortening (scMWS) (β = - 0.44) and estimated glomerular filtration rate (β = - 0.16), all p < 0.05. Higher RWT was associated with higher systolic blood pressure (β = 0.16), longer E-wave deceleration time (β = 0.23) and lower scMWS (β = - 0.66), irrespective of LV mass (all p < 0.05). CONCLUSION. Subclinical hypertensive heart disease is highly prevalent in untreated native hypertensive Tanzanians and associated with both systolic and diastolic LV dysfunction. Management of hypertension in Africans should include high focus on subclinical hypertensive heart disease.

Impact of overweight and obesity on cardiac benefit of antihypertensive treatment

BACKGROUND AND AIMS

Increased body mass index (BMI) has been associated with increased cardiovascular morbidity and mortality in hypertension. Less is known about the impact of BMI on improvement in left ventricular (LV) structure and function during antihypertensive treatment.

METHODS AND RESULTS

Annual BMI, echocardiograms and cardiovascular events were recorded in 875 hypertensive patients with LV hypertrophy during 4.8 years randomized treatment in the Losartan Intervention For Endpoint reduction in hypertension (LIFE) echocardiography substudy. Patients were grouped by baseline BMI into normal (n = 282), overweight (n = 405), obese (n = 150) and severely obese groups (n = 38) (BMI ≤24.9, 25.0-29.9, 30.0-34.9, and ≥35.0 kg/m(2), respectively). At study end, residual LV hypertrophy was present in 54% of obese and 79% of severely obese patients compared to 31% of normal weight patients (both p < 0.01). In regression analyses, adjusting for initial LV mass/height(2.7), higher BMI predicted less LV hypertrophy reduction and more reduction in LV ejection fraction (both p < 0.05), independent of blood pressure reduction, diabetes and in-study weight change. During follow-up, 91 patients suffered cardiovascular death, myocardial infarction or stroke. In Cox regression analysis 1 kg/m(2) higher baseline BMI predicted a 5% higher rate of cardiovascular events and 10% higher cardiovascular mortality over 4.8 years (both p < 0.05).

CONCLUSIONS

In hypertensive patients in the LIFE study, increased BMI was associated with less reduction of LV hypertrophy and less improvement in LV systolic function which may contribute to the observed higher cardiovascular event rate of treated hypertensive patients.

Stroke volume-to-wall stress ratio as a load-adjusted and stiffness-adjusted indicator of ventricular systolic performance in chronic loading

Load-adjusted measures of left ventricle (LV) systolic performance are limited by dependence on LV stiffness and afterload. To our knowledge, no stiffness-adjusted and afterload-adjusted indicator was tested in models of pressure (POH) and volume overload hypertrophy (VOH). We hypothesized that wall stress reflects changes in loading, incorporating chamber stiffness and afterload; therefore, stroke volume-to-wall stress ratio more accurately reflects systolic performance. We used rat models of POH (ascending aortic banding) and VOH (aorto-cava shunt). Animals underwent echocardiography and pressure-volume analysis at baseline and dobutamine challenge. We achieved extreme bidirectional alterations in LV systolic performance, end-systolic elastance (Ees), passive stiffness, and arterial elastance (Ea). In POH with LV dilatation and failure, some load-independent indicators of systolic performance remained elevated compared with controls, while some others failed to decrease with wide variability. In VOH, most, but not all indicators, including LV ejection fraction, were significantly reduced compared with controls, despite hyperdynamic circulation, lack of heart failure, and preserved contractile reserve. We related systolic performance to Ees adjusted for Ea and LV passive stiffness in multivariate models. Calculated residual Ees was not reduced in POH with heart failure and was reduced in VOH, while it positively correlated to dobutamine dose. Conversely, stroke volume-to-wall stress ratio was normal in compensated POH, markedly decreased in POH with heart failure, and, in contrast with LV ejection fraction, normal in VOH. Our results support stroke volume-to-wall stress ratio as a load-adjusted and stiffness-adjusted indicator of systolic function in models of POH and VOH.

Compensatory remodeling of coronary microvasculature maintains shear stress in porcine left-ventricular hypertrophy

BACKGROUND

Hypertension-induced left-ventricular hypertrophy (LVH) is generally accompanied with coronary neovascularization. The extent of vascular growth or rarefaction depends on many factors (e.g. age, duration of hypertension, degree of hypertrophy). Here, we hypothesize that there is a compensatory vascular growth that maintains uniform wall shear stress (WSS) in perfusion arterioles (diameters of 8-60 μm) in LVH of young porcine.

METHOD

To test this hypothesis, we investigated LVH in young porcine after 5 weeks of supravalvular aortic stenosis (3 months of age). The morphometry (diameters, lengths, number and connectivity of vessels) of the entire left circumflex (LCx) arterial tree was determined and a hemodynamic network analysis was used to calculate the distribution of pressure, flow and WSS throughout the tree in the control and LVH groups.

RESULTS

It was found that the number of vessels and the weight of left ventricle (LV) in hypertrophy increased 1.5 and 1.2 times, respectively, and the length of the LCx main trunk increased by 3 cm (36% increase), as compared with those in control group. There were similar myocardial blood flows of 0.87 ± 0.24 and 0.94 ± 0.38 ml/min per g in control and LVH hearts, respectively. The compensatory remodeling in early LVH restores WSS in the smaller perfusion arterioles, but not in the larger epicardial branches.

CONCLUSION

The present findings quantify the structural and functional remodeling in the entire LCx arterial tree in response to LVH, which reflect heterogeneity in vascular morphometry and hemodynamics from small to large vessels. These conclusions enhance our understanding of compensatory vascular remodeling in LVH of pediatric heart.

Association of heart failure hospitalizations with combined electrocardiography and echocardiography criteria for left ventricular hypertrophy

BACKGROUND

The value of performing echocardiography in hypertensive patients with electrocardiographic left ventricular hypertrophy (LVH) is uncertain.

METHODS

Baseline echo- and electrocardiographic data and cardiovascular events over 4.8 years study treatment were assessed in 922 hypertensive patients in the Losartan Intervention For Endpoint reduction in hypertension echocardiography substudy. Patients were grouped according to presence of LVH on both electrocardiogram (ECG) and echocardiogram (n = 515), only on ECG (n = 172), only on echocardiogram (n = 135), or on none tests (n = 100). LVH was diagnosed by Sokolow Lyon and Cornell product criteria by electrocardiography and as LV mass index >116 g/m(2) in men and >104 g/m(2) in women by echocardiography.

RESULTS

Patients with LVH on both tests were older, had higher systolic blood pressure and LV mass, lower LV systolic function, and included more patients with aortic regurgitation, albuminuria, and history of ischemic heart disease (all P < 0.05). Incidence of combined myocardial infarction, stroke, or cardiovascular death did not differ between groups. Incidence of hospitalization for heart failure was 5.3 and 2.6 times higher in patients with LVH on both tests compared to patients with LVH on ECG or echocardiogram only (P < 0.01). In Cox regression, LVH on both tests predicted hospitalization for heart failure (hazard ratio 4.29 (95% confidence interval 1.26-14.65), P = 0.020) independent of other covariates including study treatment allocation and history of ischemic heart disease.

CONCLUSIONS

Our results suggest that combining LVH assessment on a single ECG and echocardiogram provides a simple tool for additional heart failure risk stratification in asymptomatic high-risk hypertensive patients.

Aortic stiffness and distensibility in top-level athletes

BACKGROUND

Although cardiac adaptation to different sports has been extensively described, the potential relationship of training with aortic root (AR) elastic properties and diameters in top-level athletes remains not fully investigated. The aims of this study were to compare AR morphology and stiffness between highly trained athletes and sedentary subjects and to assess the independent determinants of AR stiffness and distensibility in athletes.

METHODS

Four hundred ten elite athletes (220 endurance-trained athletes [ATE] and 190 strength-trained athletes [ATS]; 290 men; mean age, 28.3 ± 13.6 years; age range, 18-40 years) and 240 healthy controls underwent standardized comprehensive transthoracic echocardiography, including Doppler studies. End-diastolic AR diameters were measured at four locations: the aortic annulus, the sinuses of Valsalva, the sinotubular junction, and the maximal diameter of the proximal ascending aorta. The aortic distensibility index was calculated as 2 × (systolic proximal ascending aortic diameter - diastolic proximal ascending aortic diameter)/(diastolic proximal ascending aortic diameter) × (pulse pressure) (cm(-2)·dyn(-1)·10(-6)). AR stiffness index was defined as (systolic blood pressure/diastolic blood pressure)/(systolic proximal ascending aortic diameter - diastolic proximal ascending aortic diameter)/diastolic proximal ascending aortic diameter. Analysis of variance was performed to evaluate differences among groups.

RESULTS

Left ventricular (LV) mass index did not significantly differ between the two groups of athletes but was lower in controls. ATS showed higher body surface area, sum of wall thickness (septum plus LV posterior wall), and circumferential end-systolic stress, while LV stroke volume and LV end-diastolic volume were greater in ATE. AR diameters at all levels and AR stiffness were significantly greater in ATS than in ATE and controls, while AR distensibility was significantly higher in ATE. However, AR dilatation was observed only in four male power athletes (1%). By multivariate analyses, in the overall population of athletes, age, LV stroke volume, endurance training, and duration of training were the only independent determinant of higher AR distensibility. On the other hand, age, circumferential end-systolic stress, strength training, and duration of training were independently associated with AR stiffness in ATS.

CONCLUSIONS

AR diameters and stiffness were significantly greater in strength-trained athletes, while aortic distensibility was higher in endurance athletes compared with age- and sex-matched healthy controls.

Range of right heart measurements in top-level athletes: the training impact

OBJECTIVES

To explore the full range of right heart dimensions and the impact of long-term intensive training in athletes.

BACKGROUND

Although echocardiography has been widely used to distinguish the athlete's heart from pathologic left ventricular (LV) hypertrophy, only few reports have described right ventricular (RV) and right atrial (RA) adaptations to extensive physical exercise.

METHODS

650 top-level athletes [395 endurance- (ATE) and 255 strength-trained (ATS); 410 males (63.1%); mean age 28.4 ± 10.1; 18-40 years] and 230 healthy age- and sex-comparable controls underwent a transthoracic echocardiographic exam. Along with left heart parameters, right heart measurements included: RV end-diastolic diameters at the basal and mid-cavity level; RV base-to-apex length; RV proximal and distal outflow tract diameters; RA long and short diameters; and RA area. Tricuspid annular plane systolic excursion and RV tissue Doppler systolic peak velocity were assessed as indexes of RV systolic function. Pulmonary artery systolic pressure (PASP) was estimated from the peak tricuspid regurgitant velocity.

RESULTS

ATS showed increased sum of wall thickness and relative wall thickness, whereas left atrial volume, LV end-diastolic volume, LV stroke volume and PASP were significantly higher in ATE. RV and RA measurements were all significantly greater in ATE than in ATS and controls. ATE also showed improved early diastolic RV function, whereas RV systolic indexes were comparable among groups. On multivariate analysis, type and duration of training (p<0.01), PASP (p<0.01) and LV stroke volume (p<0.001) were the only independent predictors of the main RV and RA dimensions in athletes.

CONCLUSIONS

This study delineates the upper limits of RV and RA dimensions in highly-trained athletes. Right heart measurements were all significantly greater in elite endurance-trained athletes than in age- and sex-matched strength athletes and controls. This should be considered as a "physiologic phenomenon" when evaluating athletes for sports eligibility.

Ovine models for chronic heart failure

PURPOSE

Testing and optimizing of surgical therapies for chronic heart failure (CHF) requires large animal models. CHF has been induced in several large animal species. Sheep have modest body mass increase and demonstrate docile behavior and are therefore a preferred species in research on surgical therapies for CHF METHODS: A literature search for existing ovine CHF models was performed, using search terms "sheep" and "heart failure". Relevant secondary references were traced.

RESULTS

Rapid ventricular pacing produces rapid-onset CHFE Its severity ranges from moderate left ventricular failure to severe biventricular failure, depending on length and frequency of pacing. Its counterpart in human CHF is tachycardia-induced HF since it is reversible upon cessation of pacing. Myocardial damage models include CHF induced by cardiototoxic drugs and ischemia. Ischemia-based models include coronary microembolization, occlusion and ischemia/reperfusion models. The microembolization model is relevant to diabetic cardiomyopathy. Coronary occlusion models exhibit variable functional impairment, some with aneurysm formation, and some with mitral valve regurgitation, depending on occlusion localization. They are relevant to CHF following non-reperfused myocardial infarction. Coronary occlusion/reperfusion models are relevant to the occurrence of human ãã despite coronary artery recanalization. Pressure overload of left and right ventricle is induced by aortic and pulmonary artery banding, respectively. Hypertrophy precedes CHF as in patients with valve stenosis and hypertension. Volume overload is induced by valve damage or shunt creation. Atrioventricular valve regurgitation is the most important clinical counterpart.

CONCLUSION

Several ovine CHF models exist. Since they exhibit important cardiac pathology differences, the choice of model should be based on the specific experimental question.