Comparison of echocardiographic methods for assessment of left ventricular shortening and wall stress

Left Ventricular Wall Stress and Incident Heart Failure in Elderly Community-Dwelling Individuals

Background

Greater left ventricular (LV) wall stress is associated with adverse outcomes among patients with prevalent heart failure (HF). Less is known about the association between LV wall stress and incident HF.

Objectives

The purpose of the study was to identify clinical factors associated with wall stress and test the association between wall stress and incident HF.

Methods

We studied 4,601 ARIC (Atherosclerosis Risk In Communities) study participants without prevalent HF who underwent echocardiography between 2011 and 2013. LV end systolic and diastolic wall stress (LVESWS, LVEDWS) were calculated from chamber and wall thickness, systemic blood pressure, and transmitral Doppler E/e' as a surrogate for LV end diastolic pressure. Incident HF was ascertained by International Classification of Diseases (ICD)-9/10 claims for hospitalized HF through December 31, 2016. We used Cox regression to test the association between wall stress and incident HF, adjusted for demographics, traditional cardiovascular risk factors, prevalent coronary artery disease and atrial fibrillation, creatinine, N-terminal pro-B-type natriuretic peptide, troponin, triglycerides, C-reactive protein, LV ejection fraction, and LV mass.

Results

The cohort had a median age of 75 years and 58% women, with 18% identifying as Black. Median LVESWS and LVEDWS were 48.8 (25th-75th percentile: 39.3-60.1) and 18.9 (25th-75th percentile: 15.8-22.5) kdynes/cm2, respectively. LVESWS and LVEDWS were modestly related (rho = 0.30, P < 0.001). Over 4.6 years of median follow-up (156 HF events), each 1 kdyne/cm2 greater LVEDWS was significantly associated with higher risk of incident HF (HR: 1.03; 95% CI: 1.01-1.06), while LVESWS was not (HR: 1.00; 95% CI: 0.99-1.01).

Conclusions

Among community-dwelling elderly individuals, greater LVEDWS is associated with a higher risk for incident HF.

Influence of left ventricular ejection fraction on the reduction in N-terminal pro-brain natriuretic peptide by canagliflozin in patients with heart failure and type 2 diabetes: a sub analysis of the CANDLE trial

AIM

To investigate the effect of left ventricular ejection fraction (LVEF) on the behavior of N-terminal pro-brain natriuretic peptide (NT-proBNP) levels in patients with heart failure and type 2 diabetes mellitus with the use of canagliflozin compared to glimepiride.

METHODS

Patients (n = 233) from the CANDLE trial were randomly assigned to either the add-on canagliflozin (n = 113) or glimepiride treatment groups (n = 120). The patients were followed-up for 24 weeks. The NT-proBNP levels were measured at baseline and after 24 weeks. The LVEF was determined at baseline.

RESULTS

There was a significant relationship between the baseline NT-proBNP level (X1) and the change in NT-proBNP levels from baseline to 24 weeks (Y) in the canagliflozin group (Y = -0.533 × X1 + 178; r = -0.860, p < 0.001). However, this relationship was not observed in the glimepiride group (p = 0.428). The baseline LVEF (X2) correlated with Y with a marginal significance in the canagliflozin group (Y = 7.72 × X2-549; r = 0.192, p = 0.054), but no relationship was observed in the glimepiride group. In the canagliflozin group, bivariate regression analysis showed a significant correlation between Y, X1, and X2; Y = -0.567 × X1-6.04 × X2 + 542 (R = 0.871, p < 0.001). The partial regression coefficients of X1 (p < 0.001) and X2 (p = 0.006) significantly explained the variance in Y. The correlation coefficient for X2 was negative. There was a significant relationship between the logarithmically transformed NT-proBNP [ln(NT-proBNP)] at baseline (X1') and the change in ln(NT-proBNP) values from baseline to 24 weeks (Y'), a surrogate of the rate of change in NT-proBNP levels, in the canagliflozin group (Y' = -0.18 × X1' + 0.93; r = 0.450, p = 0.001).

CONCLUSIONS

The baseline NT-proBNP level significantly affected the extent and the rate of its decrease by canagliflozin. The reduction in NT-proBNP levels by canagliflozin was prominent in patients with a higher LVEF at baseline. However, its confounding effect of LVEF on canagliflozin treatment was not recognized without adjusting for the NT-proBNP level at baseline.

Clinical Assessment of Ventricular Wall Stress in Understanding Compensatory Hypertrophic Response and Maladaptive Ventricular Remodeling

Ventricular wall stress (WS) is an important hemodynamic parameter to represent myocardial oxygen demand and ventricular workload. The normalization of WS is regarded as a physiological feedback signal that regulates the rate and extent of ventricular hypertrophy to maintain myocardial homeostasis. Although hypertrophy is an adaptive response to increased biomechanical stress, persistent hypertrophic stimulation forces the stressed myocardium into a progressive maladaptive process called ventricular remodeling, consisting of ventricular dilatation and dysfunction in conjunction with the development of myocyte hypertrophy, apoptosis, and fibrosis. The critical determinant of this pathological transition is not fully understood, but an energetic mismatch due to uncontrolled WS is thought to be a central mechanism. Despite extensive basic investigations conducted to understand the complex signaling pathways involved in this maladaptive process, clinical diagnostic studies that translate these molecular and cellular changes are relatively limited. Echocardiographic assessment with or without direct measurement of left ventricular pressure used to be a mainstay in estimating ventricular WS in clinical medicine, but in recent years more and more noninvasive applications with magnetic resonance imaging have been studied. In this review article, basic clinical applications of WS assessment are discussed to help understand the progression of ventricular remodeling.

The determinants of plasma brain natriuretic peptide level in severe aortic valve stenosis patients undergoing transcatheter aortic valve implantation

BACKGROUND

Brain or B-type natriuretic peptide (BNP) is an objective marker to diagnose the presence of heart failure (HF) and assess its severity. However, the determinants of serum BNP level in elderly patients with severe aortic valve stenosis (AS) referred for transcatheter aortic valve implantation (TAVI) have not been well investigated.

METHODS

We prospectively studied 106 AS patients who underwent TAVI. Cardiac catheterization, transesophageal echocardiography, and blood collection for plasma BNP level measurements were performed simultaneously just before the TAVI procedures.

RESULTS

Ninety-nine patients (83.9±5.0 years, 33% male) were studied. The natural logarithm of BNP (lnBNP) level was 5.4±0.9 pg/mL. Significant correlations with lnBNP level were observed in: 1) the history of syncope, prior HF medication, and New York Heart Association class III or IV (R=0.255, p=0.011) (R=0.210, p=0.037) (R=0.402, p<0.001), 2) albumin and hemoglobin level (R=-0.289, p=0.004) (R=0.263, p=0.009), 3) Left ventricular (LV) ejection fraction and global longitudinal strain (LVGLS) (R=-0.338, p<0.001) (R=0.447, p<0.001), 4) LV end-diastolic volume index (EDVI), LV mass index, and left atrial volume index (R=0.280, p=0.005) (R=0.366, p<0.001) (R=0.337, p<0.001), 5) the catheter-measured pressure gradient across the aortic valve (AVPG) (R=0.365, p<0.001). Note that LV wall stress was not significantly correlated with lnBNP level. LVGLS, AVPG, hemoglobin level, and LVEDVI were independently correlated with ln BNP level (R=0.652, LVGLS; β=0.395, p<0.006, AVPG; β=0.291, p=0.001, hemoglobin level; β=-0.216, p=0.011, and LVEDVI; β=0.203, p=0.016, respectively).

CONCLUSIONS

In severe AS patients candidate for TAVI, multiple factors, including the severities of AS and HF conditions and subclinical LV dysfunction determined by LVGLS affects plasma BNP level.

Heart and Cardiovascular Involvement in Patients with Mucopolysaccharidosis Type IVA (Morquio-A Syndrome)

BACKGROUND

Mucopolysaccharidosis (MPS) IVA is a rare lysosomal storage disorder with multiple skeletal and non-skeletal abnormalities requiring multiple surgical interventions. It is well known that patients with MPS IVA suffer from tachycardia, but cardiac and hemodynamic alterations have not been reported to date. We investigated the cardiovascular and hemodynamic alterations in patients with MPS IVA and developed a possible patho-mechanism for cardiovascular deterioration during anesthesia.

MATERIAL AND METHODS

In this observational study, serial cardiac examinations were performed in 54 patients with MPS IVA who were followed at the Children's Hospital of the Mainz Medical University (Mainz, Germany) between 1991 and 2014 (follow-up 1-24 years; median 5.8 years). Results were compared with data from a large central European cohort of more than 2000 healthy infants and children.

RESULTS

None of the patients had arterial hypertension, but 4% had evidence of increased pulmonary artery pressure. Patients developed aortic root extension up to 6.9 standard deviations above normal. Left-sided valve leaflet thickening occurred in 26 patients (five with valve disease). Patients had lower left ventricular dimensions (z: -1.02±0.1), lower stroke volumes (z: -2.3±0.17), lower left ventricular mass (z: -1.5±0.21), but higher wall thickness (z: +0.8±0.16), and higher work index (z: +2.5±0.2) compared to healthy control subjects. Cardiac output was preserved by an increase in heart rate of 21%. Sixty % of patients showed impaired diastolic filling; heart rate (99.0±1.8 vs. 92.0±2.1 bpm), age (18.0±1.8 vs. 14.2±1 years), and cardiothoracic ratio (61.6±3.6% vs. 55±4.2%) of these patients were higher compared to those with normal filling.

CONCLUSIONS

The results of this study suggest an age-progressive disproportion of the intra-thoracic organs of patients with MPS IVA, which is accompanied by aortic root extension and thickened left ventricles, with reduced stroke volumes, impaired diastolic filling patterns, and increased heart rates.

Diastolic tissue Doppler indexes correlate with the degree of collagen expression and cross-linking in heart failure and normal ejection fraction

OBJECTIVES

We attempted to correlate echocardiographic analysis of diastolic function with changes of myocardial collagen in middle-aged patients with heart failure (HF) despite normal ejection fraction (EF).

BACKGROUND

Increased collagen deposition may contribute to the deterioration of the left ventricular compliance and diastolic dysfunction in HF.

METHODS

We investigated 41 patients (median age 50 years [interquartile range: 41 to 57 years]) with normal EF (median 62% [interquartile range: 56% to 70%]) whose endomyocardial biopsies were taken previously. Assessment of diastolic function was performed by mitral-flow and tissue Doppler measurements. Sirius red and immunohistologic staining was performed to determine collagen volume fraction (CVF) and cross-linking, collagen types I and III expression, and lysyl-oxidase (LOX) expression. Expression of collagen messenger ribonucleic acid was determined by real-time polymerase chain reaction.

RESULTS

Twenty-six patients with HFNEF with diastolic dysfunction showed a significant increase in total collagen and collagen I expression compared with that of 15 controls. This was accompanied with enhanced collagen cross-linking and LOX overexpression in HFNEF. Among all flow Doppler, only deceleration time of E was associated with CVF (R = 0.43), whereas tissue Doppler parameters correlated with CVF, collagen I at the protein and mRNA levels (E' [R = -0.58, -0.60, -0.45]; E'/A' [R = -0.32, -0.36, -0.31]), and left ventricular filling index (E/E' [R = 0.72, 0.68, 0.63]), respectively. No correlation with collagen III was found. The degree of collagen cross-linking and LOX expression was related to E' (R = -0.55 and -0.60) and E/E' (R = 0.72 and 0.71), respectively, but not to flow Doppler. Collagen overexpression correlated with reduced exercise capacity.

CONCLUSIONS

Patients with HFNEF showed increased content of myocardial collagen type I, enhanced collagen cross-linking, and LOX expression, which were associated with impaired diastolic tissue Doppler parameters.

NAD(P)H oxidase p22(phox) polymorphism and cardiovascular function in amateur runners

AIM

NAD(P)H system represents the major source of superoxide production at cardiovascular (CV) level. It has several genetic variants: in particular, the C242T polymorphism of its p22(phox) subunit is associated with a different oxidase activity, being the T allele related to a lower superoxide production. Although several authors investigated the protective effect of T allele in CV diseases, only few data are available on its functional role in physiological conditions. The aim of our study was to investigate the relationship between the p22(phox) C242T polymorphism and CV function in amateur runners.

METHODS

Seventy-three male amateur runners were screened for CYBA polymorphism. CV analysis was performed by echocardiographic-Doppler examination and by PulsePen tonometer assessment.

RESULTS

The genetic subgroups (CC and CT/TT) did not differ for VM O(2max) and cardiac dimension. Nevertheless, T carriers (n = 40) were characterized by a more efficient myocardial contraction and left ventricular (LV) filling, as evidenced by significant higher values of the midwall fractional shortening, systolic excursion of the tricuspid annular plane and of early/late diastolic wave velocities ratio and by a lower E wave deceleration time. Pulse wave velocity and augmentation index, parameters related to the arterial stiffness, were higher in CC subjects compared with CT/TT also when the analysis was adjusted for weight and diastolic pressure.

CONCLUSION

In amateur runners, CYBA variants may influence both systolic and diastolic function and arterial stiffness. We suppose that the lower oxidative activity that characterizes 242T subjects may positively influence the excitation-contraction and arterial-ventricular coupling mechanisms, thus leading to a more efficient CV function.

Left ventricular dysfunction induced by nonsevere idiopathic pulmonary arterial hypertension: a pressure-volume relationship study

RATIONALE

Severe increase in right ventricular pressure can compromise left ventricular (LV) function because of impaired interventricular interaction and aggravate the symptoms.

OBJECTIVES

To elucidate how nonsevere idiopathic pulmonary arterial hypertension (IPAH) influences LV function because of impaired interventricular interaction.

METHODS

Invasive pressure-volume (PV) loop analysis obtained by conductance catheterization was performed at rest and during atrial pacing in patients with mild IPAH (n = 10) compared with patients with isolated LV diastolic dysfunction (DD) (n = 10) and control subjects without heart failure symptoms (n = 9).

MEASUREMENTS AND MAIN RESULTS

Patients with nonsevere IPAH (pulmonary artery pressure mean 29 ± 5 mm Hg) and patients with DD showed preserved systolic (ejection fraction 63 ± 12% and 62 ± 9%) and impaired LV diastolic function at rest (LV stiffness 0.027 ± 0.012 ml(-1) and 0.029 ± 0.014 ml(-1)). During pacing at 120 per minute patients with IPAH and DD decreased their stroke volume (-25% and -30%; P < 0.05) and failed to increase cardiac output significantly. Opposite to patients with DD and control subjects, temporary preload reduction during inferior vena cava occlusion initially induced an expansion of LV end-diastolic volume in IPAH (+7%; P < 0.05), whereas end-diastolic pressure continuously dropped. This resulted in an initial downward shift to the right of the PV loop indicating better LV filling, which was associated with a temporary improvement of cardiac output (+11%; P < 0.05) in the patients with IPAH, but not in patients with DD and control subjects.

CONCLUSIONS

Mild idiopathic pulmonary arterial pressure impairs LV diastolic compliance even in the absence of the intrinsic LV disease and contributes to the reduced cardiac performance at stress.

Left ventricular wall stress compendium

Left ventricular (LV) wall stress has intrigued scientists and cardiologists since the time of Lame and Laplace in 1800s. The left ventricle is an intriguing organ structure, whose intrinsic design enables it to fill and contract. The development of wall stress is intriguing to cardiologists and biomedical engineers. The role of left ventricle wall stress in cardiac perfusion and pumping as well as in cardiac pathophysiology is a relatively unexplored phenomenon. But even for us to assess this role, we first need accurate determination of in vivo wall stress. However, at this point, 150 years after Lame estimated left ventricle wall stress using the elasticity theory, we are still in the exploratory stage of (i) developing left ventricle models that properly represent left ventricle anatomy and physiology and (ii) obtaining data on left ventricle dynamics. In this paper, we are responding to the need for a comprehensive survey of left ventricle wall stress models, their mechanics, stress computation and results. We have provided herein a compendium of major type of wall stress models: thin-wall models based on the Laplace law, thick-wall shell models, elasticity theory model, thick-wall large deformation models and finite element models. We have compared the mean stress values of these models as well as the variation of stress across the wall. All of the thin-wall and thick-wall shell models are based on idealised ellipsoidal and spherical geometries. However, the elasticity model's shape can vary through the cycle, to simulate the more ellipsoidal shape of the left ventricle in the systolic phase. The finite element models have more representative geometries, but are generally based on animal data, which limits their medical relevance. This paper can enable readers to obtain a comprehensive perspective of left ventricle wall stress models, of how to employ them to determine wall stresses, and be cognizant of the assumptions involved in the use of specific models.

Patterns of left ventricular remodeling in chronic heart failure: prevalence and prognostic implications

BACKGROUND AND AIM

Many descriptors of left ventricular (LV) remodeling have important prognostic implications in patients with chronic systolic heart failure (HF). We sought to assess the prognostic value of the combination of increased LV mass with a disproportion between wall thickness and internal diameter.

METHODS AND PATIENTS

Patients (n = 536) with chronic HF, ejection fraction <50% and LV end-diastolic volume index >91 mL/m(2), classified according to LV mass index and relative wall thickness (RWT), were followed up for 33 ± 21 months. Ventricular mass was determined using a standard M-mode echocardiographic method. Relative wall thickness was defined as the ratio of (sum of interventricular septum thickness in diastole + posterior wall thickness in diastole)/LV end-diastolic diameter.

RESULTS

Prevalence of the pattern of increased LV mass index, defined as LV mass index >148 g/m(2) in men and >122 g/m(2) in women, and decreased RWT (<0.34) was 29%. Multivariable predictors of all-cause mortality were age >70 years (P < .0001), New York Heart Association class >2 (P < .0001), increased LV mass index, and decreased RWT (P = .003), E wave deceleration time ≤140 ms (P = .005), and male gender (P = .025). Patients with increased LV mass index and decreased RWT had a worse survival (33%) than patients with less LV mass index and normal to reduced RWT (log-rank 23.92; P < .0001). Comparisons of Cox models showed that the combination of increased mass index and decreased RWT added prognostic value to a model that included ejection fraction and end-systolic volume index.

CONCLUSION

In patients with systolic HF, an independent and incremental risk of adverse outcome was associated with increased mass index and decreased RWT.

Brain natriuretic peptide and the athlete's heart: a pilot study

BACKGROUND

The role of brain natriuretic peptide (BNP) in differentiating the athlete's heart from maladaptive cardiac hypertrophy is unclear.

METHODS

To address this issue, an integrated M mode, two-dimensional B mode and Doppler echocardiographical study were performed and plasma BNP levels were measured in 25 strength athletes, 25 patients with established hypertrophic cardiomyopathy (HCM) and 25 healthy volunteers.

RESULTS

Among athletes, BNP levels correlated negatively with the total training time (r = -0.79, p = 0.002) and positively with ejection fraction (r = 0.58, p = 0.049) and fractional shortening (r = 0.57, p = 0.049). A BNP cut-off value of 11.8 pg/ml had 88% specificity and 74% negative predictive value for the exclusion of HCM.

CONCLUSIONS

Brain natriuretic peptide might be useful as a preparticipation screening test in athletes.

Simultaneous estimation of NT-proBNP on top to mitral flow Doppler echocardiography as an accurate strategy to diagnose diastolic dysfunction in HFNEF

BACKGROUND

Conventional echocardiography has limited accuracy in detecting diastolic dysfunction and NT-proBNP is known to be a reliable biomarker to rule out heart failure. Therefore NT-proBNP on top to conventional mitral flow Doppler might improve the diagnostic of diastolic dysfunction in patients with heart failure despite normal EF (HFNEF) without using tissue Doppler.

METHODS AND RESULTS

Diastolic function of 46 patients with HFNEF was determined by pressure-volume loop obtained by conductance-catheter measurements. LV stiffness correlated with the amount of collagen types I and III analyzed from endomyocardial biopsies (EMBs). NT-proBNP plasma levels correlated with LV stiffness, LVEDP and the collagen amount from EMBs (p<0.01). In another set of patients with HFNEF (n=107, 53 [45-62] years), diastolic dysfunction was confirmed by left and/or right heart catheterization. Their Doppler indices and plasma marker NT-proBNP values were compared with those of 73 controls (186 [70-342] vs 54[30-75] pg/ml, p<0.001). Mitral flow Doppler was impaired in 70/107 (65%) of the HFNEF. When additional criterium NT-proBNP>125 pg/ml was used 96/107 (90%) patients with impaired diastolic function were recognized. Sensitivity of tissue Doppler indices E'/A' and E/E' were improved by 4-6% using NT-proBNP on top. NT-proBNP recognized HFNEF patients with higher hospitalization rate indicated by phone questionnaire, whereas Doppler indices alone did not.

CONCLUSION

Plasma NT-proBNP levels are associated with increased LV stiffness and cardiac collagen content. On top measurements of plasma NT-proBNP improve the echocardiography diagnostic of diastolic function and prognostic of rehospitalization in HFNEF.

Aortic elastic properties of patients with neurocardiogenic syncope

OBJECTIVE

Neurocardiogenic syncope (NCS) is a common clinical problem; however, hemodynamic mechanism is not clearly understood. Aim of the present study was to investigate aortic elastic parameters of patients with NCS provoked by head-up tilt test.

MATERIAL AND METHOD

We conducted a prospective study of 40 cases referred to our institution for head-up tilt testing. Group I constituted as 22 patients who developed mixed response and were enrolled for analysis. Hemodynamic data were compared with subjects of negative head-up tilt test (Group II). Aorta-diastolic and aorta-systolic diameters, aortic strain, aortic distensibility, aortic elastic modulus, and aortic stiffness index were calculated from transthoracic echocardiographically derived diameters of thoracic aorta.

RESULTS

Aortic distensibility (mean+/-SD; 2.7+/-1.2 cm2xdyn(-1)x10(-6) vs 4.0+/-1.2 cm2xdyn(-1)x10(-6), P=0.003) and aortic strain index (mean+/-SD; 7.0+/-1.8% vs 8.7+/-2.9%, P=0.042) were lower, and aortic stiffness index (mean+/-SD; 27.6+/-10.9 vs 20.9+/-6.18, P=0.035) and aortic elastic modulus (mean+/-SD; 0.94+/-0.7 cm2xdyn(-1)x10(-6) vs 0.49+/-0.1 cm2xdyn(-1)x10(-6), P=0.009) were higher in patients in Group I compared with those in Group II. There was no difference between two groups for following clinical variables: aorta-diastolic and aorta-systolic diameters, systolic and diastolic blood pressure, pulse pressure, E/A, weight, height, and body mass index.

CONCLUSIONS

Findings of this study have shown that elastic properties of aorta are impaired in patients with NCS. The data suggest that increase in aortic stiffness might be one of the determinants responsible for NCS. This proposal of novel link should be confirmed in further studies.

Coronary flow reserve in idiopathic dilated cardiomyopathy: relation with left ventricular wall stress, natriuretic peptides, and endothelial dysfunction

Studies have demonstrated impaired coronary blood flow reserve (CBFR) in idiopathic dilated cardiomyopathy (IDCM). It was the aim of this study to examine the potential underlying mechanisms for CBFR reduction in patients with IDCM by Doppler ultrasound techniques. Forty-eight clinically stable patients with heart failure caused by IDCM (New York Heart Association classes 1-3) were evaluated by echocardiographic and Doppler techniques with the assessments of CBFR and brachial artery flow-mediated dilation (FMD). CBFR was estimated as the hyperemic (dipyridamole: 0.84 mg/kg in 10 minutes, intravenously) to resting coronary diastolic peak velocities ratio. N-terminal pro-brain natriuretic peptide (Nt-pro-BNP) plasma levels were measured at the time of the index echocardiogram. Left ventricular (LV) ejection fraction was 30% +/- 8%, and wall motion score index was 2.0 +/- 0.25. The best correlation with CBFR was found with LV wall thickness-to-cavity radius (r = 0.77, P < .0001). A strong correlation of log-transformed Nt-pro-BNP levels was observed with CBFR (r = -0.64; P < .0001). No significant correlation was documented between CBFR and FMD. The stepwise regression model showed that LV wall thickness-to-cavity radius was the strongest independent predictor of CBFR followed by New York Heart Association class and log-transformed Nt-pro-BNP leading to a cumulative R value of 0.82 (P < .0001). The results of the study indicate that by measuring variables related to LV end-diastolic wall stress, such as LV wall thickness-to-cavity radius and plasma Nt-proBNP, it is possible to have information about CBFR in patients with heart failure secondary to IDCM.

Nonmyocardial production of ST2 protein in human hypertrophy and failure is related to diastolic load

OBJECTIVES

This study was designed to investigate: 1) relationships between serum ST2 levels and hemodynamic/neurohormonal variables; 2) myocardial ST2 production; and the 3) expression of ST2, membrane-anchored ST2L, and its ligand, interleukin (IL)-33, in myocardium, endothelium, and leukocytes from patients with left ventricular (LV) pressure overload and congestive cardiomyopathy.

BACKGROUND

Serum levels of ST2 are elevated in heart failure. The relationship of ST2 to hemodynamic variables, source of ST2, and expression of ST2L and IL-33 in the cardiovascular system are unknown.

METHODS

Serum ST2 (pg/ml; median [25th, 75th percentile]) was measured in patients with LV hypertrophy (aortic stenosis) (n = 45), congestive cardiomyopathy (n = 53), and controls (n = 23). ST2 was correlated to N-terminal pro-brain natriuretic peptide, C-reactive protein, and hemodynamic variables. Coronary sinus and arterial blood sampling determined myocardial gradient (production) of ST2. The levels of ST2, ST2L, and IL-33 were measured (reverse transcriptase-polymerase chain reaction) in myocardial biopsies and leukocytes. The ST2 protein production was evaluated in human endothelial cells. The IL-33 protein expression was determined (immunohistochemistry) in coronary artery endothelium.

RESULTS

The ST2 protein was elevated in aortic stenosis (103 [65, 165] pg/ml, p < 0.05) and congestive cardiomyopathy (194 [69, 551] pg/ml, p < 0.01) versus controls (49 [4, 89] pg/ml) and correlated with B-type natriuretic peptide (r = 0.5, p < 0.05), C-reactive protein (r = 0.6, p < 0.01), and LV end-diastolic pressure (r = 0.38, p < 0.03). The LV ST2 messenger ribonucleic acid was similar in aortic stenosis and congestive cardiomyopathy versus control (p = NS). No myocardial ST2 protein gradient was observed. Endothelial cells secreted ST2. The IL-33 protein was expressed in coronary artery endothelium. Leukocyte ST2L and IL-33 levels were highly correlated (r = 0.97, p < 0.001).

CONCLUSIONS

In human hypertrophy and failure, serum ST2 correlates with the diastolic load. Though the heart, endothelium, and leukocytes express components of ST2/ST2L/IL-33 pathway, the source of circulating serum ST2 is extra-myocardial.

Porous tissue grafts sandwiched with multilayered mesenchymal stromal cell sheets induce tissue regeneration for cardiac repair

AIMS

To provide the basis for uniform cardiac tissue regeneration, a spatially uniform distribution of adhered cells within a scaffold is a prerequisite. To achieve this goal, a bioengineered tissue graft consisting of a porous tissue scaffold sandwiched with multilayered sheets of mesenchymal stromal cells was developed.

METHODS AND RESULTS

This tissue graft (sandwiched patch) was used to replace the infarcted wall in a syngeneic Lewis rat model with an experimentally chronic myocardial infarction (MI). There were four treatment groups (n >/= 10): sham, MI, empty patch, and sandwiched patch. After a 7 day culture of the sandwiched patch, a tissue graft with relatively uniform cell concentrations was obtained. The cells were viable and tightly adhered to the tissue scaffold, as the endogenous extracellular matrix inherent with multilayered cell sheets can act as an adhesive agent for cell attachment and retention. At retrieval, the area of the empty patch was relatively enlarged, suggesting reduced structural support, while that of the sandwiched patch remained about the same (P = 0.56). In the immunofluorescent staining, host cells together with neo-microvessels were clearly observed in the empty patch; however, there were still a large number of unfilled pores within the patch. In the sandwiched patch, besides host cells, originally seeded cells were populated within the entire patch. No apparent evidence of apoptotic cell death was found in both studied patches. Thus, the sandwiched-patch-treated hearts demonstrated a better heart function to the empty-patch-treated hearts (P < 0.05).

CONCLUSION

The results demonstrated that this novel bioengineered tissue graft can serve as a useful cardiac patch to restore the dilated left ventricle and stabilize heart functions after MI.

B-type natriuretic peptide and wall stress in dilated human heart

Background Although B-type natriuretic peptide (BNP) is used as complimentary diagnostic tool in patients with unknown thoracic disorders, many other factors appear to trigger its release. In particular, it remains unresolved to what extent cellular stretch or wall stress of the whole heart contributes to enhanced serum BNP concentration. Wall stress cannot be determined directly, but has to be calculated from wall volume, cavity volume and intraventricular pressure of the heart. The hypothesis was, therefore, addressed that wall stress as determined by cardiac magnetic resonance imaging (CMR) is the major determinant of serum BNP in patients with a varying degree of left ventricular dilatation or dysfunction (LVD). Methods A thick-walled sphere model based on volumetric analysis of the LV using CMR was compared with an echocardiography-based approach to calculate LV wall stress in 39 patients with LVD and 21 controls. Serum BNP was used as in vivo marker of a putatively raised wall stress. Nomograms of isostress lines were established to assess the extent of load reduction that is necessary to restore normal wall stress and related biochemical events. Results Both enddiastolic and endsystolic LV wall stress were correlated with the enddiastolic LV volume (r = 0.54, P < 0.001; r = 0.81, P < 0.001). LV enddiastolic wall stress was related to pulmonary pressure (capillary: r = 0.69, P < 0.001; artery: r = 0.67, P < 0.001). Although LV growth was correlated with the enddiastolic and endsystolic volume (r = 0.73, P < 0.001; r = 0.70, P < 0.001), patients with LVD exhibited increased LV wall stress indicating an inadequately enhanced LV growth. Both enddiastolic (P < 0.05) and endsystolic (P < 0.01) wall stress were increased in patients with increased BNP. In turn, BNP concentration was elevated in individuals with increased enddiastolic wall stress (>8 kPa: 587 +/- 648 pg/ml, P < 0.05; >12 kPa: 715 +/- 661 pg/ml, P < 0.001; normal < or =4 kPa: 124 +/- 203 pg/ml). Analysis of variance revealed LV enddiastolic wall stress as the only independent hemodynamic parameter influencing BNP (P < 0.01). Using nomograms with "isostress" curves, the extent of load reduction required for restoring normal LV wall stress was assessed. Compared with the CMR-based volumetric analysis for wall stress calculation, the echocardiography based approach underestimated LV wall stress particularly of dilated hearts. Conclusions In patients with LVD, serum BNP was increased over the whole range of stress values which were the only hemodynamic predictors. Cellular stretch appears to be a major trigger for BNP release. Biochemical mechanisms need to be explored which appear to operate over this wide range of wall stress values. It is concluded that the diagnostic use of BNP should primarily be directed to assess ventricular wall stress rather than the extent of functional ventricular impairment in LVD.

Effects of hemoglobin concentration and creatinine clearance in pro-B-type natriuretic peptide-based left ventricular filling pressure prediction in patients with preserved left ventricular systolic function

Although N-terminal pro-B-type natriuretic peptide (pro-BNP) has been shown to correlate with left ventricular (LV) filling pressure, pro-BNP-based LV filling pressure prediction has some limitations due to several factors that affect pro-BNP. The aim of this study was to evaluate the effects of blood hemoglobin concentration and creatinine clearance (CCr) on pro-BNP-based LV filling pressure prediction in patients with preserved LV systolic function. A total of 421 consecutive patients referred for coronary angiography underwent LV pressure measurement by fluid-filled catheters. Patients with plasma creatinine levels>or=1.5 mg/dl and LV ejection fractions<50% were excluded. LV diastolic pressures and echocardiographic parameters were compared with pro-BNP levels in 281 patients. Blood hemoglobin levels and CCr were measured simultaneously. Log pro-BNP was independently correlated with hemoglobin concentration (beta=-0.261, p<0.001), CCr (beta=-0.230, p<0.001) and LV pre-A-wave pressure (beta=0.384, p<0.001). A pro-BNP level of 124 pg/ml was the optimal cutoff for LV pre-A-wave pressure>15 mm Hg in all patients (sensitivity 67%, specificity 67%, p<0.001). However, by subclassification according to hemoglobin and CCr tertiles, optimal cut-off values varied significantly, and their predictive accuracies could be improved (from 89 to 331 pg/dl, with diagnostic accuracy up to 79%). In conclusion, in the pro-BNP-based prediction of elevated LV filling pressure, subclassification on the basis of hemoglobin concentration and CCr should be considered in patients with preserved LV systolic and renal function.

Abnormal regional myocardial deformation properties and increased aortic stiffness in normotensive patients with aortic coarctation despite successful correction: an ABPM, standard echocardiography and strain rate imaging study

The long-term follow-up data subsequent to a successful repair of AoC (aortic coarctation) show that life expectancy remains reduced. Previous standard echocardiographic studies have demonstrated normal or increased systolic cardiac function in patients following successful repair of AoC. SR (strain rate) imaging is a new technique able to detect subclinical myocardial abnormalities. In the present study we investigated whether young patients (without hypertension, as assessed using ambulatory blood pressure monitoring and an exercise test) following successful AoC repair already have abnormal myocardial deformation properties, and the relationship of the deformation properties with aortic stiffness. We studied 166 subjects, 83 AoC non-hypertensive patients (mean age 12+/-4 years) a number of years after successful repair of AoC and 83 age- and sex-matched subjects as controls. Peak systolic SR (1/s) for both regional longitudinal and radial function was assessed. The aortic stiffness index was calculated from the echocardiographically derived thoracic aortic diameters, and the measurement of blood pressure was obtained by cuff sphygmomanometry. The LV (left ventricular) ejection fraction was significantly increased in AoC patients, whereas regional longitudinal SRs were significantly reduced (-1.1+/-0.9 compared with -2+/-0.5, P<0.0001) in patients. The aortic stiffness index was significantly increased in AoC patients (12+/-9, P<0.0001). At multilinear regression analysis, age at repair (P=0.005; coefficient, -0.201; S.E.M., 0.027) and the aortic stiffness index (P=0.0029; coefficient, 0.334; S.E.M., 0.423) predicted longitudinal SR. Despite the presence of a successful repair for AoC, in the absence of hypertension, longitudinal deformation properties were significantly impaired. Moreover, the degree of longitudinal SR impairment was correlated with age at repair and aortic stiffness. Early repair can delay the onset of hypertension in postcoarctectomy patients, but cannot prevent the innate structural and functional abnormalities of the aorta and their deleterious effect on myocardial deformation properties.

Utility of Doppler echocardiography and tissue Doppler imaging in the estimation of diastolic function in heart failure with normal ejection fraction: a comparative Doppler-conductance catheterization study

BACKGROUND

Various conventional and tissue Doppler echocardiographic indexes were compared with pressure-volume loop analysis to assess their accuracy in detecting left ventricular (LV) diastolic dysfunction in patients with heart failure with normal ejection fraction (HFNEF).

METHODS AND RESULTS

Diastolic dysfunction was confirmed by pressure-volume loop analysis obtained by conductance catheter in 43 patients (19 men) with HFNEF. Their Doppler indexes were compared with those of 12 control patients without heart failure symptoms and with normal ejection fraction. Invasively measured indexes for diastolic relaxation (tau, dP/dt(min)), LV end-diastolic pressure, and LV end-diastolic pressure-volume relationship (stiffness, b [dP/dV], and stiffness constant, beta) were correlated with several conventional mitral flow and tissue Doppler imaging indexes. Conventional Doppler indexes correlated moderately with the degree of LV relaxation index, tau (E/A: r=-0.36, P=0.013; isovolumic relaxation time: r=0.31, P=0.040) and b (deceleration time: r=0.39, P=0.012) but not with beta, in contrast to the tissue Doppler imaging indexes E'/A'(lateral) (r=-0.37, P=0.008) and E/E'(lateral) (r=0.53, P<0.001). Diastolic dysfunction was detected in 70% of the HFNEF patients by mitral flow Doppler but in 81% and 86% by E'/A'(lateral), and E/E'(lateral), respectively.

CONCLUSIONS

Of all echocardiographic parameters investigated, the LV filling index E/E'(lateral) was identified as the best index to detect diastolic dysfunction in HFNEF in which the diagnosis of diastolic dysfunction was confirmed by conductance catheter analysis. We recommend its use as an essential tool for noninvasive diagnostics of diastolic function in patients with HFNEF.

Effect of endovascular stenting of aortic coarctation on biventricular function in adults

OBJECTIVE

To investigate the effect of endovascular stenting of aortic coarctation on biventricular function in adults during intermediate-term follow-up.

METHODS

21 patients (age 34 (10) years) were studied prospectively before and 14 (2) months after coarctation stenting from year 2002 to 2005. Biventricular function and blood pressure measurements were made. The post-stenting results were compared with pre-stenting values (group 1), with 22 age- and sex-matched post-surgical repair patients (group 2) and 30 normal controls (group 3).

RESULTS

The peak systolic gradient across the coarctation site fell (55 (15) mm Hg to 18 (8) mm Hg, p<0.001). Systolic, mean blood pressure and left ventricular (LV) mass dropped after stenting (p<0.05 for all). LV long-axis function improved at intermediate-term follow-up (tissue Doppler imaging lateral and septal systolic and diastolic velocities and E/Em ratios: LSm, 6.5 (1.4) cm/s to 7.9 (1.7) cm/s; SSm, 5.8 (1.2) cm/s to 7.3 (1.6) cm/s; LEm, 8.1 (1.3) to 9.4 (2.3) cm/s; SEm, 6.7 (1.5) cm/s to 7.8 (1.9) cm/s; LE/Em, 11.2 (2.7) to 9.8 (2.8); SE/Em, 14.8 (5.3) to 11.8 (3.9); p<0.05 for all). No significant difference in LV ejection fraction, conventional LV diastolic measurements (E, A, E/A ratio, IVRT and DT) was found after stenting. No significant deterioration of right ventricular function was seen in stented patients. Both post-stenting and post-surgical repair patients had poorer LV long-axis function than controls (p<0.01 for all).

CONCLUSIONS

Endovascular stenting of aortic coarctation resulted in medium-term LV mass regression and long-axis function improvement that may provide insight into long-term outcome of the stented patients. The results support aortic stenting in patients with anatomically suitable defects, given the additional benefit of avoiding cardiopulmonary bypass. The clinical significance of subclinical myocardial dysfunction in patients with stented or repaired coarctation warrants further studies.

Aortic elastic properties in patients with coronary artery ectasia

BACKGROUND

The purpose of the present study was to investigate the elastic characteristics of the aorta in patients with coronary ectasia (CE) and the relationship between these characteristics and echocardiographic left ventricular (LV) diastolic functions.

METHODS AND RESULTS

In the first group there were 35 patients with CE, the second group consisted of 35 patients with coronary artery disease (CAD) and the third group consisted of 35 patients with normal coronary arteries. Echocardiographic investigation was carried out for the assessment of the LV diastolic functions. Aortic strain, beta index and aortic distensibility were used as aortic elasticity parameters. LV diastolic functions were impaired in both the ectasia group and the CAD group as compared with patients with normal coronary arteries. Beta index and aortic distensibility measurements were similar between the CAD and CE groups. The values obtained for aortic strain, beta index and aortic distensibility were lower in the CAD and ectasia groups when compared with the values of the normal group. On performing the stepwise linear multivariable analyses, aortic elastic parameters have been determined to possess the strongest diagnostic power for LV diastolic functions.

CONCLUSIONS

The results of the current study show that stiffness parameters of aorta are impaired in the patients with CE as in the patients with CAD. The increase in aortic stiffness might be responsible for LV diastolic dysfunction.

Effect of chronic afterload increase on left ventricular myocardial function in patients with congenital left-sided obstructive lesions

The effect of pressure-overloading distance on left ventricular (LV) function in patients with congenital aortic coarctation and aortic stenosis (AS) was investigated. LV long-axis motions were recorded using M-mode and tissue Doppler imaging (TDI) techniques in 46 consecutive patients with severe LV outflow tract obstruction (23 coarctation and 23 AS), and results were compared with those of 23 controls. TDI lateral and septal long-axis systolic velocities, early diastolic velocities, and M-mode systolic amplitudes were lower in patients with coarctation and AS than controls (lateral site long-axis systolic velocity 7.1 +/- 1.7 and 6.4 +/- 1.6 vs 9.7 +/- 1.7 cm/s, septal site long-axis systolic velocity 6.3 +/- 1.3 and 5.4 +/- 1.1 vs 7.7 +/- 1.3 cm/s; lateral site early diastolic velocity 10.5 +/- 2.2 and 8.2 +/- 2.6 vs 13.1 +/- 2.5 cm/s, septal site early diastolic velocity 7.4 +/- 1.9 and 6.0 +/- 1.8 vs 10.8 +/- 1.6 cm/s, lateral site M-mode systolic amplitude 1.4 +/- 0.2 and 1.3 +/- 0.2 vs 1.6 +/- 0.2 cm, septal site M-mode systolic amplitude 1.2 +/- 0.2 and 1.1 +/- 0.2 vs 1.4 +/- 0.2 cm, p <0.01 for all). Compared with patients with coarctation, those with AS had lower TDI velocities, higher early LV filling velocity/long-axis diastolic velocity ratios, and a higher prevalence of long-axis incoordination (p <0.05 for all) despite similar LV mass index, ejection fraction, and systolic wall stress. In conclusion, LV long-axis function is impaired in patients with a chronic increase in afterload. Worse deterioration in LV function and higher prevalence of long-axis incoordination independent of LV outflow resistance is seen in patients with proximally increased LV afterload (AS) compared with distal disease (aortic coarctation).

Beraprost sodium enhances neovascularization in ischemic myocardium by mobilizing bone marrow cells in rats

Beraprost sodium, an orally active prostacyclin analogue, has vasoprotective effects such as vasodilation and antiplatelet activities. We investigated the therapeutic potential of beraprost for myocardial ischemia. Immediately after coronary ligation of Sprague-Dawley rats, beraprost (200 microg/kg/day) or saline was subcutaneously administered for 28 days. Four weeks after coronary ligation, administration of beraprost increased capillary density in ischemic myocardium, decreased infarct size, and improved cardiac function in rats with myocardial infarction. Beraprost markedly increased the number of CD34-positive cells and c-kit-positive cells in plasma. Also, four weeks after coronary ligation of chimeric rats with GFP-expressing bone marrow, bone marrow-derived cells were incorporated into the infarcted region and its border zone. Treatment with beraprost increased the number of GFP/von Willebrand factor-double-positive cells in the ischemic myocardium. These results suggest that beraprost has beneficial effects on ischemic myocardium partly by its ability to enhance neovascularization in ischemic myocardium by mobilizing bone marrow cells.

Alterations in the Pattern of Collagen Deposition May Contribute to the Deterioration of Systolic Function in Hypertensive Patients With Heart Failure

OBJECTIVES

We sought to assess the distribution of collagen deposits and collagen degradation in hypertensive patients with either systolic heart failure (SHF) or diastolic heart failure (DHF).

BACKGROUND

Increased collagen synthesis and deposition have been described in the myocardium of heart failure (HF) hypertensive patients.

METHODS

We studied 39 HF hypertensive patients subdivided into two groups: 16 with SHF and 23 with DHF. Endomyocardial biopsies were performed to quantify mysial (i.e., perimysial plus endomysial) and perivascular and scar-related collagen volume fraction (CVF). Matrix metalloproteinase (MMP)-1 and its tissue inhibitor matrix metalloproteinase (TIMP)-1 were analyzed in cardiac samples by Western blot and immunohistochemistry, and in blood samples by enzyme-linked immunosorbent assay.

RESULTS

Mysial CVF was lower in SHF hypertensive patients than in normotensive (p < 0.05) and DHF hypertensive patients (p < 0.01). Perivascular and scar-related CVF was higher (p < 0.05) in the two groups of hypertensive patients than in normotensive subjects, and in SHF hypertensive compared with DHF hypertensive patients. The MMP-1:TIMP-1 ratio was increased (p < 0.05) in tissue and serum samples from the SHF hypertensive group compared with the other two groups of subjects. The MMP-1 expression was increased (p < 0.01) in the interstitium and cardiomyocytes of SHF hypertensive patients compared with DHF hypertensive and normotensive subjects. The serum MMP-1:TIMP-1 ratio was inversely correlated with ejection fraction (r = -0.510, p < 0.001) and directly correlated with left ventricular end-diastolic diameter (r = 0.549, p < 0.001) in all subjects.

CONCLUSIONS

These findings show that the pattern of collagen deposits and the balance of the MMP-1/TIMP-1 system are different in the myocardium of SHF and DHF hypertensive patients. It is proposed that excessive degradation of mysial collagen may be related to the compromise of systolic function in HF hypertensive patients.

Patients With Hibernating Myocardium Show Altered Left Ventricular Volumes and Shape, Which Revert After Revascularization

OBJECTIVES

The purpose of this study was to investigate whether post-ischemic left ventricular (LV) remodeling might be induced by regional contractile dysfunction per se (i.e., in the absence of transmural necrosis) and whether this phenomenon is potentially reversible after contractile recovery.

BACKGROUND

Formation of extensive scar tissue is thought to be chiefly responsible for post-infarction LV remodeling; however, myocardial necrosis also causes loss of contractility. We investigated LV geometry and shape in a setting in which contractile dysfunction occurs in the presence of preserved myocyte viability, and thus it is potentially reversible.

METHODS

In 42 patients with chronically dysfunctional myocardium, we evaluated (by two-dimensional echocardiography) LV global and regional function, volumes, and sphericity index (SI), at baseline and 8 +/- 3 months after coronary revascularization. Myocardial viability before revascularization was evaluated by dobutamine echocardiography.

RESULTS

At baseline, regional and global function were depressed and LV dilation was present. Revascularization was followed by recovery of ejection fraction (from 33 +/- 6% to 45 +/- 10%, p < 0.0001) and wall motion score index (from 2.29 +/- 0.31 to 1.74 +/- 0.42, p < 0.0001). After revascularization, significant improvement of end-systolic volume index (from 78 +/- 23 ml/m2 to 56 +/- 23 ml/m2, p < 0.0001), end-diastolic volume index (from 118 +/- 26 ml/m2 to 99 +/- 26 ml/m2, p < 0.0001), and SI (from 0.69 +/- 0.14 to 0.52 +/- 0.11, p < 0.0001) was also observed. Improvement in LV volumes and SI were significantly correlated to the number of segments recovering function after revascularization.

CONCLUSIONS

Hibernating myocardium is associated with major alterations in LV volumes and shape, which significantly revert after revascularization. Thus, chronic dyssynergy per se is sufficient to induce ischemic LV remodeling in patients.

B-type natriuretic peptide strongly reflects diastolic wall stress in patients with chronic heart failure: comparison between systolic and diastolic heart failure

OBJECTIVES

We explored the stimulus for B-type natriuretic peptide (BNP) secretion in the clinical setting of heart failure (HF).

BACKGROUND

Increasingly, plasma BNP levels are being incorporated into the clinical assessment and management of systolic heart failure (SHF) as well as diastolic heart failure (DHF). However, heterogeneity in BNP levels among individuals with HF can cause some confusion in interpreting results.

METHODS

In 160 consecutive patients presenting with HF, we measured plasma BNP levels and performed echocardiography and cardiac catheterization. Systolic and diastolic meridional wall stress was calculated from echocardiographic and hemodynamic data.

RESULTS

Although plasma BNP had a significant correlation (r2 = 0.296 [p < 0.001]) with left ventricular end-diastolic pressure (EDP) as previously reported, the correlation between plasma BNP and end-diastolic wall stress (EDWS) (r2 = 0.887 [p < 0.001]) was more robust. In a subanalysis of 62 patients with DHF, a similar result was obtained (r2 = 0.143 for EDP and r2 = 0.704 for EDWS). In a comparison between SHF and DHF, the BNP level was significantly higher in SHF (p < 0.001). Although EDP did not show any difference, EDWS was significantly higher in SHF than in DHF (p < 0.001).

CONCLUSIONS

The present study shows that plasma BNP levels reflect left ventricular EDWS more than any other parameter previously reported, not only in patients with SHF, but also in patients with DHF. The relationship of left ventricular EDWS to plasma BNP may provide a better fundamental understanding of the interindividual heterogeneity in BNP levels and their clinical utility in the diagnosis and management of HF.

Effect of Obstructive Sleep Apnea on Aortic Elastic Parameters

BACKGROUND

Obstructive sleep apnea (OSA) syndrome has a critical association with cardiovascular mortality and morbidity. Aortic elastic parameters are important markers for left ventricular (LV) function and are deteriorated in cardiovascular disease.

METHODS AND RESULTS

Aortic elastic parameters and LV functions and mass were investigated in 40 patients with OSA (apnea - hypopnea index (AHI) >or=5) (mean age 51.3 +/-9 years, 32 males) and 24 controls (AHI <5) (mean age 51.9+/-5.2 years, 19 males). All subjects underwent polysomnographic examination and recordings were obtained during sleep. They also underwent a complete echocardiographic examination and systolic and diastolic aortic measurements were noted from M-mode traces of the aortic root. There were no significant differences in the demographic data of the patients with OSA and the controls. Subjects with OSA demonstrated higher values of aortic stiffness (7.1+/-1.88 vs 6.42+/-1.56, p=0.0001), but lower distensibility (9.47+/-1.33 vs 11.8+/-3.36, p=0.0001) than the controls. LV ejection fraction was significantly lower in patients with OSA when compared with the control group (61.3+/-5.2% vs 65.9+/-8.4%, p=0.0001). LV diastolic parameters were also compared and were worse in the subjects with OSA than in the control subjects (mitral E/A: 0.91 +/-0.42 vs 1.35+/-0.66, p=0.001; Em/Am: 0.86+/-0.54 vs 1.23+/-0.59, p=0.021). Respiratory disturbance index had a positive correlation with aortic stiffness (r=0.63, p=0.0001 and negative correlation with distensibility (r=-0.41, p=0.001).

CONCLUSION

Aortic elastic parameters are deteriorated in OSA, which has an extremely high association with cardiovascular disease. Increased aortic stiffness might be responsible for the LV systolic and diastolic deterioration in OSA syndrome.

Aortic elastic properties and left ventricular diastolic dysfunction in patients with obstructive sleep apnea

Although the responsible mechanisms are not yet fully known, obstructive sleep apnea is associated with an increased risk for cardiovascular disease and events. The aorta is not only a conduit delivering blood to the tissues but is also an important modulator of the entire cardiovascular system, its elastic properties also affecting left ventricular function and coronary blood flow. The aim of this study was to determine left ventricular diastolic function and aortic elastic properties in patients with obstructive sleep apnea syndrome. Fourteen male patients with obstructive sleep apnea and 14 age- and body mass index-matched healthy male controls took part in the study as a control group. All subjects underwent echocardiographic examination; left ventricular cavity dimension, standard and tissue Doppler parameters, and aortic diameter (3 cm above aortic valve) at systole and diastole were measured. While the aortic stiffness index in patients with obstructive sleep apnea was significantly higher than that of the control group (4.5 +/- 0.3 vs 2.1 +/- 0.1, P = 0.001), the aortic distensibility index was found to be lower in this group compared with controls (2.4 +/- 1.2 vs 3.9 +/- 1.5 cm2 dynes(-1) 10(-6), P = 0.009). Furthermore, peak velocity of myocardial systolic wave and peak velocities of myocardial diastolic waves in sleep apnea patients were lower than in controls. There was an association between aortic stiffness and the apnea hypopnea index (coefficient = 0.49, P = 0.002). We also found an inverse correlation between peak velocity of myocardial diastolic wave and aortic stiffness (coefficient = -0.43, P = 0.003), using multiple linear regression. Increased aortic stiffness that is associated with the severity of disease in patients with obstructive sleep apnea may lead to diastolic dysfunction of the left ventricle.

Effects of biventricular pacing on interstitial remodelling, tumor necrosis factor-α expression, and apoptotic death in failing human myocardium

AIMS

Recent data from the COMPANION trial have documented that cardiac resynchronization therapy (CRT) with biventricular (BiV) pacing reduces mortality and hospitalization in patients with advanced CHF, but little is known regarding the cellular and molecular mechanisms of CRT. Our aim is to evaluate interstitial remodelling, tumor necrosis factor-alpha (TNF-alpha) expression, and apoptosis in patients with advanced CHF treated with CRT.

METHODS AND RESULTS

We performed endomyocardial biopsies in 10 patients, aged 62, with dilated cardiomyopathy before and 6 months after the implantation of a BiV pacing device. Clinical status and left ventricular (LV) architecture and function were assessed as well as myocardial histology, TNF-alpha expression, and apoptotic index. CRT improved clinical status, as shown by a significant reduction of the Minnesota living with heart failure questionnaire (MLHFQ) score (from 53 to 40) and 6-min walked distance (from 290 to 330 m) (all P<0.05 vs. baseline). This was associated with reverse LV remodelling substantiated by significant reductions of LV volumes and end-systolic circumferential wall stress. Examination of myocardial tissue revealed a significant decrease of collagen volume fraction (CVF) (from 25.16 to 18.0%), TNF-alpha expression (from 9.5 to 3.6 pixel x 10(3)), and apoptotic index (from 2030 to 1408 apoptotic nuclei/10(6)), with increased capillary density (from 1801 to 2011 capillary/mm(2)) after 6 months of CRT (all P<0.05 vs. baseline). Moreover, changes in TNF-alpha expression were positively correlated with both CVF and end-systolic circumferential wall stress (r=0.80 and 0.70, respectively).

CONCLUSION

We provide the first evidence that CRT reduces interstitial remodelling, TNF-alpha expression, and apoptosis. The data may explain the beneficial effects of CRT on CHF progression and survival.

Adjunctive handgrip during dobutamine stress echocardiography: invasive assessment of myocardial oxygen consumption in humans

BACKGROUND

Adjunctive isometric exercise in the form of sustained submaximal handgrip (HG) is considered to increase the sensitivity of dobutamine stress echo (DSE) for detection of functionally significant coronary artery disease.

HYPOTHESIS

The study was undertaken to quantify invasively the impact of HG in humans on hemodynamics and myocardial oxygen consumption (MVO2) during DSE.

METHODS

An invasive hemodynamic evaluation was performed during DSE and with addition of adjunctive HG in 11 subjects. Coronary sinus (CS) blood flow, right-sided and systemic pressures, oxygen saturations, and transthoracic two-dimensional echocardiography were obtained at each 3-min stage and after adding HG at peak DSE. Myocardial oxygen consumption was calculated by the Fick method and circumferential end-systolic wall stress (ESWS) by Mirsky's formula.

RESULTS

At peak DSE, heart rate, left ventricular ejection fraction, CS flow, and MVO2 increased, whereas pulmonary capillary wedge pressure (PCWP) and circumferential end-systolic wall stress (ESWS) decreased from baseline. Compared with peak DSE, the addition of isometric HG at peak DSE caused an increase in PCWP (7 +/- 3 vs. 8.4 +/- 3 mmHg, p < 0.05), ESWS (112 +/- 25 x 103 vs. 125 +/- 32 x 103 dyne x s x cm2, p = 0.02), and CS flow (260 +/- 92 vs. 301 +/- 105 ml/min, p < 0.05). There was a minimal increase in left ventricular volumes, heart rate, and systolic blood pressure. The MVO2 increased from 29 +/- 8 ml/min at peak DSE to 31 +/- 9 ml/min with adjunctive HG (p = 0.03).

CONCLUSION

Handgrip adjunctive to peak DSE results in a modest increase in MVO2, primarily by an increase in end-systolic wall stress.

Echocardiographic predictors of morbidity and mortality in patients with advanced heart failure: the Beta-blocker Evaluation of Survival Trial (BEST)

OBJECTIVES

The aim of this study was to determine echocardiographic predictors of outcome in patients with advanced heart failure (HF) due to severe left ventricular (LV) systolic dysfunction in the Beta-blocker Evaluation of Survival Trial (BEST).

BACKGROUND

Previous studies indicate that echocardiographic measurements of LV size and function, mitral deceleration time, and mitral regurgitation (MR) predict adverse outcomes in HF. However, complete quantitative echocardiograms evaluating all of these parameters have not been reported in a prospective randomized clinical trial in the era of modern HF therapy.

METHODS

Complete echocardiograms were performed in 336 patients at 26 sites and analyzed by a core laboratory. A Cox proportional-hazards regression model was used to determine which echocardiographic variables predicted the primary end point of death or the secondary end point of death, HF hospitalization, or transplant. Significant variables were then entered into a multivariable model adjusted for clinical and demographic covariates.

RESULTS

On multivariable analysis adjusted for clinical covariates, only LV end-diastolic volume index predicted death (events = 75), with a cut point of 120 ml/m(2). Three echocardiographic variables predicted the combined end point of death (events = 75), HF hospitalization (events = 97), and transplant (events = 9): LV end-diastolic volume index, mitral deceleration time, and the vena contracta width of MR. Optimal cut points for these variables were 120 ml/m(2), 150 ms, and 0.4 cm, respectively.

CONCLUSIONS

Echocardiographic predictors of outcome in advanced HF include LV end-diastolic volume index, mitral deceleration time, and vena contracta width. These variables indicate that LV remodeling, increased LV stiffness, and MR are independent predictors of outcome in patients with advanced HF.

Wall stress modulates brain natriuretic peptide production in pressure overload cardiomyopathy

OBJECTIVES

We postulated that both diastolic and systolic load modulate B-type natriuretic peptide (BNP) production in human pressure overload hypertrophy/failure.

BACKGROUND

In isolated myocytes, diastolic stretch induces BNP messenger ribonucleic acid expression. However, the mechanism of the BNP release in human hypertrophy remains controversial.

METHODS

In 40 patients with symptomatic aortic stenosis (AS), left ventricular (LV) performance and systolic and diastolic wall stress were calculated from combined invasive and echocardiographic data. Plasma BNP was determined by the rapid point-of-care bedside analyzer (Biosite Triage, Biosite Diagnostics Inc., San Diego, California).

RESULTS

A significant relationship was observed between plasma BNP and pulmonary capillary wedge pressure (p < 0.001), fractional shortening (p = 0.001), and aortic valve area (p = 0.006). Furthermore, a significant correlation was noted between BNP and LV mass index (p = 0.005) as well as between BNP and markers of diastolic load such as LV end-diastolic wall stress (p = 0.011), indexed LV end-diastolic volume (p < 0.001), and isovolumic relaxation time (p = 0.02). Preoperative BNP levels were elevated in patients with AS compared with patients without AS. Plasma BNP was higher in AS patients with impaired versus normal preload reserve (297 +/- 56 pg/ml vs. 168 +/- 44 pg/ml; p = 0.017) and in AS patients with clinical deterioration after valve replacement compared with those without (399 +/- 82 pg/ml vs. 124 +/- 41 pg/ml; p = 0.011).

CONCLUSIONS

In patients with AS, BNP appears to be regulated not only by systolic but also by diastolic load. This supports the hypothesis that myocardial stretch modulates BNP production in human pressure overload hypertrophy/failure.

Cardiovascular response to acute normovolaemic haemodilution in patients with severe aortic stenosis: assessment with transoesophageal echocardiography

Using multiplane transoesophageal echocardiography (TOE), we investigated the haemodynamic response to acute normovolaemic haemodilution (ANH) in anaesthetised patients with critical aortic stenosis. Twenty-eight patients were randomly assigned to ANH or control groups. In the control group, haemodynamic data remained unchanged over a 20-min period. In the ANH group, haemoglobin levels decreased from a mean (SD) of 134 (7) to 91 (9) g x l(-1) (p < 0.001) whereas stroke volume, central venous pressure and left ventricular (LV) end-diastolic area all increased significantly (mean (SD) +15 (6) ml; +2.0 (1.1) mmHg; +2.1 (0.8) cm2, respectively). During ANH, the accelerated blood flow through the stenotic valve caused an increased loss (SD) in LV stroke work: from 24 (8)% to 30 (10)%), (p < 0.01). Hence, lowering viscosity with ANH resulted in improved venous return, higher cardiac preload and increased stroke volume. However, this adaptive haemodynamic response was limited by less efficient LV stroke work due to dissipation of fluid kinetic energy.

Miscellaneous Use of Exercise Echocardiography in Patients with Chronic Pulmonary Disease or Congenital Heart Defect

To date, the usage of exercise echocardiography in patients with pulmonary or congenital heart disease has been limited despite its potential for broader applications in different clinical scenarios. Exercise echocardiography can be utilized to determine the extent of pulmonary vascular damage in patients with chronic obstructive pulmonary disease by demonstrating the presence of exertional pulmonary hypertension in subjects with normal pulmonary artery pressures (PAPs) at rest. It is also useful in patients with connective tissue disease to screen for lung involvement by identifying exertional pulmonary hypertension, and in patients with established pulmonary hypertension to choose and monitor the effects of therapeutic interventions on the PAPs. Moreover, the measurement of aortic flow velocity and acceleration by exercise echocardiography may be helpful in the study of dyspnea in patients at risk for both pulmonary disease and congestive heart failure. In patients with congenital heart disease, the measurement of PAP and ventricular function both at rest and during exercise by echocardiography is the cornerstone in the investigation of the etiology of exercise intolerance in these individuals. Lastly, exercise echocardiography can also screen for residual narrowing in patients after repair of the coarctation of the aorta by detecting a significant diastolic gradient in the descending aorta during exercise provocation.

Hemodynamic effects of inducible nitric oxide synthase and nitrotyrosine generation in heart failure

OBJECTIVES

The hemodynamic effects of cardiac inducible nitric oxide synthase (iNOS) and of iNOS-mediated peroxynitrite in patients with left ventricular (LV) dysfunction are unclear. The present study investigates the incidence and functional significance of iNOS expression and nitrotyrosine formation in patients with heart failure.

METHODS

LV endomyocardial biopsies obtained from 24 patients with heart failure due to idiopathic dilated cardiomyopathy (ejection fraction [EF] <45% and left ventricular end-diastolic volume index [LVEDVI] >102 ml/m2) were analyzed for iNOS and nitrotyrosine. LV contractile performance was assessed by left ventricular ejection fraction (LVEF) and stroke work normalized for end-diastolic pressure (SW/EDP). LV filling pattern was assessed by Doppler E/A wave ratio, deceleration time (DT) of early LV filling and indexed LV end-diastolic volume normalized for EDP as a marker of diastolic distensibility.

RESULTS

iNOS immunostaining correlated significantly with nitrotyrosine formation (r = 0.86, p < 0.001). In the whole study group, patients expressing iNOS (n = 13) showed larger LV end-diastolic (173 +/-16 vs 128 +/- 9 ml/m2, p = 0.031) and end-systolic volume indices (110 +/- 16 vs 61 +/- 9 ml/m2, p = 0.018) and similar LVEDP (18 +/- 2 vs 21 +/- 2 mm Hg, p = 0.227). In patients with advanced heart failure and reduced pre-load reserve (LVEDP > 16 mm Hg, n = 18), iNOS protein and nitrotyrosine formation correlated positively with LVSW/EDP (r = 0.65, p = 0.03 and r = 0.64, p = 0.04, respectively), DT (r = 0.96, p < 0.01 and r = 0.88, p < 0.01, respectively) and inversely with E/A (r = -0.82, p < 0.01 and r = -0.88, p < 0.01, respectively). In addition, nitrotyrosine formation correlated positively with LVEDVI/EDP (r = 0.64, p = 0.02). Advanced iNOS-positive heart failure patients had a higher LVEDVI/EDP compared with iNOS-negative patients (5.30 +/- 0.64 vs 3.13 +/- 0.34 ml/mm Hg x m2, p = 0.02).

CONCLUSIONS

In heart failure, iNOS protein expression is associated with nitrotyrosine formation. Although iNOS-positive patients are generally characterized by larger LV volume and depressed function, the preserved NO generation appears to be associated with higher cardiac work due to the preserved Frank-Starling relationship in end-stage heart failure.

Prevention of diastolic heart failure by endothelin type A receptor antagonist through inhibition of ventricular structural remodeling in hypertensive heart

OBJECTIVES

Despite the clinical frequency of diastolic heart failure, its therapeutic strategy has not been established. Our recent study demonstrated activation of the endothelin (ET) system in a diastolic heart failure model with hypertension. Several studies have reported that ET type A (ETA) receptor antagonist improves systolic function and prevents systolic heart failure; however, its effects on diastolic heart failure are unknown. We investigated the effects of chronic administration of ET(A) receptor antagonist in diastolic heart failure.

DESIGN AND METHODS

Dahl-Iwai salt-sensitive rats fed on a high-salt diet from 7 weeks of age, in which congestive heart failure develops following hypertension without cardiac chamber dilatation or systolic dysfunction, were divided into groups with and without administration of a subdepressor dose of ET(A) receptor antagonist.

RESULTS

Hypertension induced compensatory left ventricular (LV) hypertrophy at 13 weeks in six untreated rats. Persistent pressure overload developed progressive LV hypertrophy and fibrosis from 13 to 19 weeks, resulting in elevated LV filling pressure and increased lung weight. Chronic ET(A) receptor blockade did not restrain compensatory LV hypertrophy at 13 weeks; however, it attenuated LV hypertrophy and fibrosis thereafter (n = 6). These beneficial effects resulted in the maintenance of normal LV filling pressure without changes in LV end-diastolic diameter, indicating prevention of LV stiffening.

CONCLUSIONS

Chronic ET(A) receptor blockade is likely to exert beneficial effects in diastolic failure through attenuation of the progression of LV hypertrophy and fibrosis.

Echo doppler assessment of left ventricular function in rats with hypertensive hypertrophy

OBJECTIVE

This study attempted to establish echocardiographic measurements of left ventricular (LV) mass and LV systolic and diastolic function, particularly in rats with hypertensive heart.

METHODS

M-mode LV echograms and Doppler mitral flow were obtained in Dahl salt-sensitive rats placed on 0.3% or 8% sodium chloride diet. Echo Doppler measurements were compared with catheterization and pathologic measurements in 54 rats for LV mass and in 45 rats for LV systolic and diastolic function.

RESULTS

Echocardiographic measurement of LV mass correlated well with pathologic measurement (r = 0.94, P <.01, n = 54, SEE = 0.08 mg), independent of LV size, aging, and therapeutic intervention. Endocardial fractional shortening (FS) correlated with LV peak + dP/dt (r = 0.56, n = 45, P <.01), and the correlation was improved to r = 0.71 if 11 rats with marked LV hypertrophy were excluded. Midwall FS correlated well with LV peak + dP/dt (r = 0.72, n = 45, P <.01) even if rats with extremely thickened ventricular wall were included. If midwall FS was lower than 14%, LV systolic dysfunction was very likely (sensitivity 67%, specificity 91%). Association of mitral E/A ratio of 2.0 or greater with deceleration time of shorter than 35 ms was an accurate indicator of elevated LV end-diastolic pressure (sensitivity 82%, specificity 86%) and increased lung weight because of congestive heart failure (sensitivity 89%, specificity 96%) in rats with hypertension.

CONCLUSION

LV mass, LV systolic function, and LV end-diastolic pressure were assessable with echo Doppler in rats with hypertensive heart.

Clinical significance of iodine-123-15-(p-iodophenyl)-3-R, S-methylpentadecanoic acid myocardial scintigraphy in patients with aortic valve disease

The present study sought to determine whether myocardial fatty acid metabolism as assessed with iodine-123-labeled 15-(p-iodophenyl)-3-R,S-methylpentadecanoic acid (BMIPP) scintigraphy is impaired in patients with aortic valve disease (AVD) and whether the degree of the metabolic abnormality reflects the severity of AVD. BMIPP scintigraphy was performed in 12 patients with aortic stenosis (AS), 14 patients with aortic regurgitation (AR), and 9 healthy volunteers, and from that the heart-mediastinum uptake ratio (H/M ratio) corrected by the left ventricular (LV) mass (U/Mass ratio) and the myocardial washout rate (WR) were obtained. The H/M ratio tended to be higher in patients than in healthy volunteers (3.3 +/- 0.7 for AS, 3.5 +/- 0.5 for AR, 3.0 +/- 0.3 for healthy volunteers), and the WR was significantly higher in patients than in healthy volunteers (42.8 +/- 9.1% for AS, 35.7 +/- 6.5% for AR, 19.6 +/- 9.1% for healthy volunteers, p<0.01). In the AS patients, the U/Mass ratio showed significant negative correlations (r=-0.79 to -0.90, all p<0.01) and the WR showed significant positive correlations (r=0.61 to 0.82, all p<0.01) with transaortic pressure gradient, LV wall thickness, and LV mass. Similarly, in AR patients these BMIPP parameters showed proportional changes to the LV volumes and LV mass (r=-0.79 to -0.83, all p<0.01 for U/Mass ratio, r=0.55 to 0.70, p<0.05 to <0.01 for WR). In the 9 patients who underwent aortic valve replacement, the BMIPP parameters tended to normalize with increasing U/Mass ratio (0.90 +/- 0.41 x 10(-2)/g to 1.34 +/- 0.59 x 10(-2)/g, p<0.05) and decreasing WR (41.9 +/- 8.8% to 35.4 +/- 9.2%, p<0.01) after surgery. Myocardial fatty acid metabolism as assessed with BMIPP scintigraphy was impaired in patients with aortic valve disease and the U/Mass ratio and WR reflect the severity. These parameters may be useful for the noninvasive assessment of the myocardial metabolic abnormalities caused by hemodynamic overload.

Growth hormone alone or combined with metoprolol preserves cardiac function after myocardial infarction in rats

BACKGROUND AND OBJECTIVE

Beta-adrenoreceptor blocking agents are important for the treatment of myocardial infarction (MI). Accumulating evidence also indicates that growth hormone (GH) improves cardiac function after MI in rats. We aimed to investigate the cardiovascular effects of combined treatment in an animal model of MI.

METHODS

MI was induced in rats by ligation of the left coronary artery. Three days after MI, animals were randomly assigned to one of four groups: controls (C) (n=19); GH (n=19) receiving s.c. 2 mg/kg per day rhGH; metoprolol (M) group (n=19) receiving 24 mg/kg per day and combined group (GHM) (n=20) treated with both GH (2 mg/kg per day s.c.) and M (24 mg/kg per day) for 9 days. Transthoracic echocardiography was performed before and after treatment.

RESULTS

Serum levels of insulin-like growth factor I were significantly elevated in the GH-group but not in the GHM group compared to controls. Left ventricular volumes, cardiac index, systolic blood pressure, were similar in all groups. Percent changes in ejection fraction compared to baseline were; GH (6.1+/-5.0%) and GHM (6.1+/-4.2%) vs. C (-12.5+/-3.0%), P<0.01, M (-7.3+/-4.2%). The occurrence of aneurysms was not significantly different between the various treatment regimes.

CONCLUSION

Treatment with growth hormone alone or in combination with metoprolol preserved left ventricular function after MI.

Chronic administration of ghrelin improves left ventricular dysfunction and attenuates development of cardiac cachexia in rats with heart failure

BACKGROUND

Ghrelin is a novel growth hormone (GH)-releasing peptide that may also induce vasodilation and stimulate feeding through GH-independent mechanisms. We investigated whether ghrelin improves left ventricular (LV) dysfunction and attenuates cardiac cachexia in rats with chronic heart failure (CHF).

METHODS AND RESULTS

Ligation of the left coronary artery or sham operation was performed; 4 weeks after surgery, rat ghrelin (100 microg/kg SC BID) or saline was administered for 3 weeks. Echocardiography and cardiac catheterization were performed. Serum GH and insulin-like growth factor-1 were significantly higher in both CHF and sham rats treated with ghrelin than in those given placebo (P<0.05 for both). CHF rats given placebo showed an impaired increase in body weight compared with sham rats given placebo (P<0.05). CHF rats treated with ghrelin, however, showed a significantly greater increase in body weight than those given placebo (+10% versus +3%, P<0.05). They showed significantly higher cardiac output (315+/-49 versus 266+/-31 mL. min(-1). kg(-1), P<0.05) and LV dP/dt(max) (5738+/-908 versus 4363+/-973 mm Hg/s, P<0.05) than CHF rats given placebo. Ghrelin increased diastolic thickness of the noninfarcted posterior wall, inhibited LV enlargement, and increased LV fractional shortening in CHF rats (from 15+/-3% to 19+/-3%, P<0.05).

CONCLUSIONS

Chronic subcutaneous administration of ghrelin improved LV dysfunction and attenuated the development of LV remodeling and cardiac cachexia in rats with CHF.

Renin angiotensin system-dependent hypertrophy as a contributor to heart failure in hypertensive rats: different characteristics from renin angiotensin system-independent hypertrophy

OBJECTIVES

This study aimed to characterize the difference between renin angiotensin system (RAS)-dependent and RAS-independent hypertrophy and their differential contribution to the transition to heart failure.

BACKGROUND

Hypertensive left ventricular (LV) hypertrophy develops with RAS activation in the heart; however, LV hypertrophy develops even without RAS activation.

METHODS

Left ventricular geometry and function were assessed in Dahl salt-sensitive rats placed on an 8% NaCl diet from seven weeks old (hypertensive rats) and in those placed on an 0.3% NaCl diet (control rats, n = 8). The hypertensive rats were randomized to no treatment (n = 8) or treatment with the angiotensin type 1 receptor (AT1R) antagonist candesartan (1 mg/kg per day, n = 10) after the baseline echocardiography study.

RESULTS

From 7 to 13 weeks, AT1R blockade at a subdepressor dose did not restrain the development of LV hypertrophy but prevented narrowing of LV diastolic dimension, leading to the normalization of abnormally decreased end-systolic wall stress in the untreated rats. Progressive development of LV hypertrophy in spite of lower than normal end-systolic wall stress (excessive hypertrophy) after 13 weeks was suppressed by the AT1R blockade. Elevation of LV end-diastolic pressure and prolongation of Tau were associated with histological evidence of myocyte hypertrophy and massive interstitial fibrosis in the untreated rats, and none of these was evident in the treated rats.

CONCLUSIONS

Renin-angiotensin system activation and AT1R signaling may be dispensable for the development of early adaptive LV hypertrophy and closely linked to the transition to heart failure.