Detection of regional left ventricular dysfunction in early pacing-induced heart failure using ultrasonic integrated backscatter

Remodeling of left circumflex coronary arterial tree in pacing-induced heart failure

Congestive heart failure (CHF) is a very serious heart disease that manifests an imbalance between left ventricle supply and demand. Although the mechanical demand of the failing heart has been well characterized, the systematic remodeling of the entire coronary arterial tree that constitutes the supply of the myocardium is lacking. We hypothesize that the well-known increase in ventricle wall stress during CHF causes coronary vascular rarefaction to increase the vascular flow resistance, which in turn compromises the perfusion of the heart. Morphometric (diameters, length, and numbers) data of the swine left circumflex (LCx) arterial tree were measured in both CHF (n = 6) and control (n = 6) groups, from which a computer reconstruction of the entire LCx tree was implemented down to the capillary level to enable a hemodynamic analysis of coronary circulation. The vascular flow resistance was increased by ∼75% due to a significant decrease of vessel numbers (∼45%) and diameters in the first capillary segments (∼10%) of the LCx arterial tree after 3-4 wk of pacing. The structural remodeling significantly changed the wall shear stress in vessel segments of the entire LCx arterial tree of CHF animals. This study enhances our knowledge of coronary arterial tree remodeling in heart failure, which provides a deeper understanding of the deterioration of supply-demand relation in left ventricle.

Selective inhibition of the master regulator transcription factor Egr-1 with catalytic oligonucleotides reduces myocardial injury and improves left ventricular systolic function in a preclinical model of myocardial infarction

BACKGROUND

Egr-1 is implicated in the pathogenesis of myocardial ischemia-reperfusion injury. The aim of this study was to ascertain the effectiveness of intracoronary delivery of DNAzyme targeting the transcription factor Egr-1 at reperfusion following experimental myocardial ischemia.

METHODS AND RESULTS

Functional DNAzyme targeting Egr-1 or a size-matched scrambled control were delivered via the intracoronary route immediately on reperfusion after 60 minutes' balloon occlusion of the left anterior descending coronary artery in a pig model of myocardial I/R injury (n=7 per treatment group). Heart function and extent of myocardial infarction were determined following intervention by echocardiography and cardiac magnetic resonance imaging, respectively. Hearts were removed and examined for molecular and histological markers of inflammation and apoptosis. Administration of functional DNAzyme led to an overall decrease in the expression of inflammatory markers including intracellular adhesion molecule-1, tissue factor, and complement 3, with associated decreases in the extent of neutrophil infiltration, oxidative damage, and subsequent apoptosis within the infarct border zone. Functional significance was indicated by an increase in salvaged left ventricular myocardium (P=0.012), ejection fraction (P=0.002), and fractional area change (P=0.039) in the functional DNAzyme-treated group compared with the control.

CONCLUSIONS

Egr-1 silencing through intracoronary delivery of a targeting DNAzyme at the time of reperfusion following acute myocardial ischemia decreases myocardial inflammation and apoptosis leading to improved cardiac function.

Intracoronary delivery of DNAzymes targeting human EGR-1 reduces infarct size following myocardial ischaemia reperfusion

Despite improvements in treatment, myocardial infarction (MI) remains an important cause of morbidity and mortality. Inflammation arising from ischaemic and reperfusion injury is a key mechanism which underpins myocardial damage and impairment of cardiac function. Early growth response-1 (Egr-1) is an early immediate gene and a master regulator that has been implicated in the pathogenesis of ischaemia-reperfusion (IR) injury. This study sought to examine the effect of selective inhibition of Egr-1 using catalytic deoxyribonucleic acid molecules (DNAzymes, DZs) delivered via the clinically relevant coronary route in a large animal model of myocardial IR. It was hypothesized that Egr-1 inhibition with intracoronary DZ would reduce infarction size by modulating its downstream effector molecules. Egr-1 DZs inhibited the adherence of THP-1 monocytes to IL-1β-activated endothelial cells in vitro and retained its catalytic activity up to 225 min after in vivo administration. In a porcine model of myocardial IR (45 min ischaemia/3 h reperfusion), DZ was taken up in the cytoplasm and nuclei of cardiomyocytes and endothelial cells in the myocardium after intracoronary delivery. Egr-1 DZs reduced infarct size and improved cardiac functional recovery following intracoronary delivery at the initiation of IR in this large animal model of MI. This was associated with inhibition of pro-inflammatory Egr-1 and ICAM-1 expression, and the reduced expression of TNF-α, PAI-1, TF, and myocardial MPO activity in tissue derived from the border zone of the infarct. Taken together, these data suggest that strategies targeting Egr-1 via the intracoronary route after IR injury in pigs have potential therapeutic implications in human MI.

Effects of thrice-weekly in-center nocturnal vs. conventional hemodialysis on integrated backscatter of myocardial tissue

Ultrasonic tissue characterization with integrated backscatter (IBS) offers a promising method for the noninvasive assessment of myocardial fibrosis and contractile performance. The aim of this study was to investigate the effect of thrice-weekly in-center nocturnal hemodialysis (INHD) and conventional hemodialysis (CHD) on myocardial fibrosis and left ventricular function in end-stage renal disease patients. Thirty-two INHD and 58 matched CHD patients were enrolled; baseline and 12-month measures of blood pressure (BP), serum calcium and phosphorus, echocardiographic left ventricular mass index (LVMI) and left ventricular function, the myocardial calibrated IBS (C-IBS), and systodiastolic cyclical variations in IBS (CV-IBS) were collected. The baseline characteristics were similar between groups, except that serum phosphorus and calcium × phosphorus were higher in the INHD group. At 12-month follow-up, there was a significant decrease in the mean C-IBS (-20.2 ± 3.7 to -28.1 ± 4.0 dB, P<0.01) and a significant increase in CV-IBS (5.0 ± 1.5 to 7.1 ± 1.6 dB, P<0.01) in INHD patients. Multivariate analysis showed that the mean C-IBS was positively related to SBP, DBP, LVMI, serum phosphorus, and left atrial volume index and inversely related to midwall fractional shortening, transmitral E/A ratio, and E(m) . The mean CV-IBS was positively correlated with left ventricular midwall fractional shortening, E/A ratio, E(m) and inversely correlated with SBP, DBP, LVMI, serum phosphorus, E/E(m) , and left atrial volume index. There was no significant change in the mean C-IBS, mean CV-IBS, and LVMI in the CHD group. Compared with CHD, INHD improves myocardial fibrosis and left ventricular function, and control of serum phosphorus is associated with the improvement of myocardial fibrosis. Improvement of myocardial fibrosis contributes to the reduction of left ventricle hypertrophy.

Cardiovascular complications in patients with pheochromocytoma: a mini-review

Phaeochromocytomas are rare neuroendocrine tumours secreting high levels of catecholamines, able to exert serious metabolic and cardiovascular effects. The serious and potentially lethal cardiovascular complications of these tumours are due to the potent effects of secreted catecholamines, especially noradrenaline, the main transmitter released from sympathetic nerve terminals. Hypertension, tachycardia, pallor, headache and anxiety, usually dominate the clinical presentation. Occasionally, patients with predominantly epinephrine-secreting tumours present hypotension or even shock. Other cardiovascular complications of pheochromocytoma include ischaemic heart disease, acute myocardial infarction, cardiac arrhythmias, heart failure due to toxic cardiomyopathy, or pulmonary edema. Catecholamines have been shown to influence the extracellular matrix with collagen deposition and subsequent fibrosis in the arterial wall and in the myocardium. These morphofunctional changes of the myocardium and of arterial wall can be emphasized by ultrasound imaging. Indeed, ultrasound imaging of the myocardium and arterial wall not only identifies wall thickness but also contains information on texture that may be revealed by acoustic tissue characterization. The latter can be quantified through videodensitometric analysis of echographic images or through ultrasonic integrated backscatter signal analysis. This paper reviews cardiovascular complications in patients with pheochromocytoma and utility of the new ultrasound technique as backscatter signal. It is useful for evaluating preclinical pathological morphofunctional changes of the myocardium and arterial wall, characterized by increased collagen content in pheochromocytoma patients. The recognition of early catecholamine-induced alterations in patients with pheochromocytoma, is important to prevent at least morbidity and mortality, before surgical treatment.

Cardiac remodeling in patients with primary aldosteronism

OBJECTIVE

To evaluate the morpho-functional changes of the myocardium in patients with primary aldosteronism (PA).

DESIGN

An observational study in a university referral center for blood pressure diseases.

PATIENTS

Twenty- three patients with PA, 24 patients with essential hypertension (EH), and 15 normotensive controls (C) underwent conventional echocardiography with integrated backscatter (IBS) and tissue Doppler imaging (TDI) analysis. The corrected IBS (C-IBS) values and the systo-diastolic variation of IBS (CV-IBS) were performed at both interventricular septum and the posterior wall levels. TDI myocardial systolic (Sm), early diastolic (Em), and late diastolic (Am) velocities of both left ventricular walls were also determined.

RESULTS

In PA patients, septal and posterior wall CV-IBS were significantly lower than C (p<0.0001) and EH patients (p<0.001). In EH, CV-IBS was significantly lower than C (p<0.001). Patients with PA exhibited lower Sm, lower Em, and higher Am, and a subsequently reduced Em/Am ratio than C (p<0.001 for all) and EH (p<0.01 for all) at interventricular septum and lateral wall levels. In the latter, Sm, Em, and Em/Am ratio were lower and Am was higher than C (p<0.001 for all). In PA and EH patients, CV-IBS at both septum (r=-0.66, p<0.001) and posterior wall levels (r=-0.67, p<0.001) and Sm peak of both septum (r=-0.52, p<0.001) and lateral wall (r=-0.55, p<0.001) were inversely related to plasma aldosterone.

CONCLUSIONS

Patients with PA showed myocardial wall remodeling characterized by increased myocardial fibrosis and early left ventricular systodiastolic function abnormalities.

Effect of cibenzoline on regional left ventricular function in hypertrophic obstructive cardiomyopathy

BACKGROUND

Cibenzoline, a class Ia antiarrhythmic drug, can be used to relieve left ventricular (LV) outflow obstruction in hypertrophic obstructive cardiomyopathy (HOCM). However, the mechanism of this agent in HOCM has been controversial.

HYPOTHESIS

This study was designed to investigate the effect of cibenzoline on regional LV function and the acoustic properties in HOCM using ultrasonic integrated backscatter.

METHODS

Ten patients with HOCM and 16 healthy volunteers were examined. In patients with HOCM, wall thickening (%WT) and the magnitude of cyclic variation of integrated backscatter (mag-CVIBS) in the interventricular septum (IVS) and LV posterior wall were measured before and after oral administration of cibenzoline. To assess asynchrony of contractile elements, the phase difference between CVIBS and %WT were measured from the LV posterior wall. Pressure gradients at the LV outflow tract were estimated using continuous-wave Doppler echocardiography.

RESULTS

Although %WT decreased significantly in the LV posterior wall, %WT and mag-CVIBS remained unchanged in the IVS. The phase difference in the LV posterior wall was significantly greater in patients with HOCM than in healthy volunteers (HOCM:healthy volunteers, 1.57 +/- 0.23:1.00 +/- 0.03, p < 0.001) at baseline. After administration of cibenzoline, the phase difference shifted to normal value (from 1.57 +/- 0.23 to 1.28 +/- 0.27, p = 0.0382), and pressure gradients at the LV outflow tract decreased (from 109 +/- 55 to 58 +/- 48 mmHg, p = 0.0063). Changes in pressure gradients at the LV outflow tract and the phase difference were closely related.

CONCLUSIONS

Regional function and the acoustic properties of myocardium in HOCM were altered by cibenzoline in the LV posterior wall but remained unchanged in the IVS. The normalization of the phase difference in the LV posterior wall was closely related to the decrease in pressure gradients at the LV outflow tract. These findings suggest that negative inotropic action and the improvement of asynchrony in the LV posterior wall rather than in the IVS may contribute to the reduction of pressure gradients at the LV outflow tract in HOCM.

Preclinical cardiac involvement in phaeochromocytoma: a study with integrated backscatter

OBJECTIVE

It is well known that vascular and cardiac structure may be influenced by circulating neurohormonal factors. Our aim was to study the myocardial wall texture by integrated backscatter (IBS) analysis in patients with phaeochromocytoma (PHEO).

DESIGN

Fourteen patients with PHEO, 15 matched high-normal blood pressure (BP) subjects, 15 mild essential hypertensives and 15 normotensive controls underwent two-dimensional conventional ultrasonography and ultrasonic IBS of the myocardial wall. IBS analysis was performed at both interventricular septum and posterior wall levels. IBS values were expressed in decibels and corrected for the IBS values obtained within the pericardium (C-IBS). The systo-diastolic cyclical variations in IBS (CV-IBS), an index of myocardial contractile performance, were also evaluated.

RESULTS

Patients with PHEO showed C-IBS values comparable to those of hypertensive patients, and significantly higher than those of high-normal BP subjects and controls at both septum and posterior wall levels (P < 0.001 for all). In PHEO patients, CV-IBS was lower than that of normotensive, high-normal BP subjects and hypertensive patients, at both septum and posterior wall levels (P < 0.001 for all). An inverse relationship was found in the PHEO group between 24-h urinary normetanephrine and CV-IBS of both septum (r(2) = -0.29, P < 0.05) and posterior wall (r(2) = -0.46, P < 0.05).

CONCLUSIONS

Our results show that patients with PHEO have myocardial remodelling characterized by increased myocardial fibrosis, confirmed by an increase in the overall myocardial backscatter level measured. The observed decrease in the magnitude of CV-IBS suggests an impairment of myocardial contractile performance. These results may provide insights into the role of catecholamines in left ventricular (LV) structure and function in PHEO.

Impact of the angiotensin II receptor antagonist, losartan, on myocardial fibrosis in patients with end-stage renal disease: assessment by ultrasonic integrated backscatter and biochemical markers

Myocardial fibrosis commonly occurs in patients with end-stage renal disease (ESRD) and has proven to be an important predictor for cardiovascular events. In experimental settings, angiotensin II type 1 receptor (AT1-R) antagonists have been shown to have anti-fibrotic effects on the myocardium independent of their antihypertensive effects. In this study, to investigate whether the AT1-R antagonist losartan would have such anti-fibrotic effects in patients, we administered losartan or, for purpose of comparison, the angiotensin-converting enzyme enalapril or Ca2+-antagonist amlodipine to patients with ESRD. Thirty-nine ESRD patients with hypertension were randomly assigned to receive losartan (n=13), enalapril (n=13), or amlodipine (n=13). Ultrasonic integrated backscatter (IBS) and serological markers of collagen type I synthesis and degradation were used to assess the degree of myocardial fibrosis just before and after 6 months of treatment. There were no significant differences in antihypertensive effects among the three agents. In the enalapril- and amlodipine-treated groups, the mean calibrated IBS values increased significantly after 6 months of treatment (enalapril: -31.6 +/- 1.3 to -29.4 +/- 1.2 dB, p=0.011; amlodipine: -30.6 +/- 1.4 to -27.2 +/- 1.2 dB, p=0.012). However, the mean calibrated IBS values in the losartan-treated group did not increase after 6 months of treatment (-31.2 +/- 1.7 to -31.3 +/- 1.4 dB, p=0.88). The ratio of the serum concentration of procollagen type I carboxy-terminal peptide to the serum concentration of collagen type I pyridinoline cross-linked carboxy-terminal telopeptide was significantly reduced in the losartan-treated group (42.6 +/- 4.6 to 34.4 +/- 3.6, p=0.038). The present study indicates that losartan more effectively suppresses myocardial fibrosis in patients with ESRD than does enalapril or amlodipine despite a comparable antihypertensive effect among the three drugs.

Left ventricular function and calcium phosphate plasma levels in uraemic patients

BACKGROUND. Recent investigations have focused on the pathogenetic role of disturbances of calcium phosphate metabolism in causing cardiovascular morbidity and mortality in haemodialysis patients. The aim of the present study was to assess left ventricular function and its relationship to phosphate and calcium plasma levels in stable uraemic patients on haemodialysis treatment.

METHODS

Twenty uraemic patients (mean age 51+/-13 years) on maintenance haemodialysis and free from overt cardiac dysfunction, and 20 healthy volunteers underwent standard echocardiography, tissue Doppler-derived early (E(m)) and late (A(m)) diastolic velocities, tissue characterization with cyclic variations of integrated backscatter (CV-IBS), and serum biochemistry.

RESULTS

With respect to tissue Doppler imaging (TDI), uraemic patients showed a lower E(m) peak, a higher A(m) peak, and a reduced E(m)/A(m) ratio of both interventricular septum and lateral wall (0.01>P<0.001) than controls. CV-IBS of both septum and posterior wall was significantly smaller in uraemic patients than in the control subjects (P<0.001). Moreover, the E(m)/A(m) ratio of septum and lateral wall were negatively related to serum phosphorus and to calcium phosphate product (P<0.001 for all). Accordingly, an inverse relationship was also found between CV-IBS of septum and lateral wall and calcium phosphate product and phosphorus (P<0.05 for all).

CONCLUSIONS

These results showed early cardiac impairment of diastolic myocardial function evaluated by TDI and IBS analysis, and a close relationship between these changes and the calcium-phosphate plasma levels. These findings are well in keeping with the important role of hyperphosphataemia as a risk factor for cardiovascular damage, and justify the effort for optimal control of calcium phosphate metabolism in uraemic patients.

Subclinical cardiac involvement in patients with facioscapulohumeral muscular dystrophy

Myocardial involvement is a common finding in certain myopathies, while it has not been extensively investigated in facioscapulohumeral muscular dystrophy (FSHD1A). Aim of this study was to assess in FSHD1A patients the electrical and functional properties of the myocardium. Twenty-four patients with FSHD1A (mean age 41.2+/-14.5 years) and 24 matched healthy subjects were studied. Standard- and signal-averaged electrocardiography were recorded to determine QT dispersion and the presence of ventricular late potentials (VLPs). Standard echocardiography with systo-diastolic variations of integrated backscatter signal (CV-IBS) were performed to assess functional properties of the myocardium. Compared with control subjects, patients with FSHD1A had significantly lower CV-IBS and higher QT dispersion. Nine patients had positive VLPs. QT and QTc dispersion were inversely related to CV-IBS at both septum and posterior wall levels. Moreover, septal CV-IBS was inversely related to the Kpnl-BinI4q fragment size. These results suggest a subclinical cardiac involvement in FSHD1A patients, which can represent a substrate for ventricular arrhythmias and heart failure.

Assessment of menopause-induced myocardial changes by integrated backscatter during inotropic stimulation and atropine injection

Estradiol has been considered as an L-type calcium channel blocker in animal studies. The concentration of estradiol decreases after menopause. Therefore, we hypothesized that human myocardial functional changes developed after menopause, and those changes could be evaluated through the use of cyclic variation of integrated backscatter (CVIBS). A total of 16 patients with menopause (native and surgical menopause), follicular stimulating hormone > 40 IU/L and estradiol < 20 pg/mL underwent dobutamine stress IBS examination (study group). Another 12 women with normal menstruation, follicular stimulating hormone < 40 IU/L and estradiol > 20 pg/mL were enrolled as a control group. All patients had a low likelihood of coronary artery disease and negative results of dobutamine stress echocardiography and (201)thallium scintigraphy. To avoid the phenomenon of anisotropy, the amplitude and phase of IBS were acquired only in the midanteroseptal segment from the parasternal short axis view. The baseline amplitudes of CVIBS differed between the control and study groups (5.9 +/- 1.2 dB vs. 8.1 +/- 2.1 dB; p = 0.007). The amplitudes during low-dose (20 microg/kg-min) and peak-dose (40 microg/kg-min) dobutamine infusion were also different between these 2 groups (5.7 +/- 0.9 dB vs. 8.4 +/- 1.7 dB; p < 0.001; 6.0 +/- 1.0 dB vs. 7.7 +/- 2.4 dB; p = 0.026). However, there were no significant differences in amplitudes between these two groups after atropine injection (control group 4.5 +/- 1.2 dB, study group 5.3 +/- 1.0 dB; p = NS). No significant differences of phase were found either at baseline or under dobutamine infusion between the two groups. Multivariate linear regression analysis showed that only menopause status associated significantly with the amplitudes at different doses of dobutamine infusion (p < 0.05). In conclusion, human myocardial functional changes are observed by CVIBS after menopause. Postmenopausal women have higher values of amplitude than premenopausal women. These phenomena persist during low and peak doses of dobutamine infusion, but are abolished by atropine injection.

Ultrasonic tissue characterization can predict beta-blocker efficacy in dilated cardiomyopathy

The aim was to determine if the combination of cyclic variation of myocardial integrated backscatter (variation IB) and left ventricular mass measurements can predict the efficacy of beta-blocker treatment in dilated cardiomyopathy. In 32 patients, left ventricular mass and variation IB were measured at baseline and during 6 microg/kg/min dobutamine infusion before the initiation of beta-blocker therapy. Variation IB was measured at left and right ventricular halves in the ventricular septum. The baseline left ventricular mass index and transseptal variation IB gradient during dobutamine were significantly greater in the effective group (1.16 +/- 0.18 g/mL and 1.8 +/- 0.6 dB) than in the ineffective group (0.94 +/- 0.28 g/mL, p = 0.032 and 0.4 +/- 0.6 dB, p < 0.005). When both baseline left ventricular mass index > or = 1.05 g/mL and transseptal variation IB gradient during dobutamine > or = 1.5 dB were defined as predictive criteria for the effective group, the sensitivity was 78% and the specificity was 86%. Analysis of transseptal variation IB during dobutamine may provide useful information predicting the efficacy of beta-blocker therapy in dilated cardiomyopathy.