Depressed Fractional Shortening Research Articles

Cardiac-specific overexpression of metallothionein attenuates L-NAME-induced myocardial contractile anomalies and apoptosis.

Hypertension contributes to the high cardiac morbidity and mortality. Although oxidative stress plays an essential role in hypertensive heart diseases, the mechanism remains elusive. Transgenic mice with cardiac overexpression of metallothionein, a heavy metal‐binding scavenger, were challenged with NG‐nitro‐L‐arginine methyl ester (L‐NAME) for 14 days prior to measurement of myocardial contractile and intracellular Ca2+ anomalies as well as cell signalling mechanisms using Western blot and immunofluorescence analysis. L‐NAME challenge elicited hypertension, macrophage infiltration, oxidative stress, inflammation and cardiac dysfunction manifested as increased proinflammatory macrophage marker F4/80, interleukin‐1β (IL‐1β), intracellular O2- production, LV end systolic and diastolic diameters as well as depressed fractional shortening. L‐NAME treatment reduced mitochondrial membrane potential (MMP), impaired cardiomyocyte contractile and intracellular Ca2+ properties as evidenced by suppressed peak shortening, maximal velocity of shortening/relengthening, rise in intracellular Ca2+, along with elevated baseline and peak intracellular Ca2+. These unfavourable mechanical changes and decreased MMP (except blood pressure and macrophage infiltration) were alleviated by overexpression of metallothionein. Furthermore, the apoptosis markers including BAD, Bax, Caspase 9, Caspase 12 and cleaved Caspase 3 were up‐regulated while the anti‐apoptotic marker Bcl‐2 was decreased by L‐NAME treatment. Metallothionein transgene reversed L‐NAME‐induced changes in Bax, Bcl‐2, BAD phosphorylation, Caspase 9, Caspase 12 and cleaved Caspase 3. Our results suggest that metallothionein protects against L‐NAME‐induced myocardial contractile anomalies in part through inhibition of apoptosis.

Bag3+ P209L Transgene Provides a Cardiac‐Specific Murine Model of Protein Misfolding and Aggregation

Bag3 is a heat shock protein expressed in skeletal muscle and cardiomyocytes that regulates proteasomal and lysosomal protein elimination pathways. Bag3, in association with Hsp70 and HspB8, assists in chaperone‐assisted selective autophagy. Several mutations in Bag3, including the P209L mutation, results in myofibrillar myopathy, a childhood‐onset disease with protein aggregation. The P209L mutation has been suggested to result in a toxic gain of function and Bag3 insufficiency. To test the role of P209L in the heart, we created a transgenic mouse with cardiac specific (α‐MHC) Bag3P209L. Longitudinal conscious echocardiography was performed over 12 months on mice, with histological analysis of apoptosis, protein aggregation, and fibroblast analysis performed upon harvest. In 8 months, Bag3 P209L Tg mice had significantly depressed fractional shortening compared to sibling wildtype control mice (FS% 38.9±1.0% vs. 48.1±0.95%, p=0.0005). However, no differences in apoptosis nor fibroblast number was identified at 12 months. No differences in amyloid protein aggregation were identified at 12 months (26.8±0.9 AU vs. 30.0±6.6 AU, p=0.76). However, analysis of cardiac tissue for pre‐amyloid oligomers will allow the more clinically relevant detection of proteotoxic intermediates that can lead to cytotoxicity, as is found in neurodegenerative diseases and other causes of heart failure. Since Bag3 is required for autophagosome formation during CASA, future studies will focus on pathological changes in cardiac autophagic flux and its related MAPK signaling. This novel Bag3 transgenic mouse model provides a useful model to characterize cardiac‐specific dysfunction we will use to identify therapeutic targets that protect against the development of cardiomyopathy.

Abstract 72: Pka Is A Master Regulator Of Pathological Cardiac Hypertrophy

Aims: The role of PKA in pathological cardiac hypertrophy (PCH) is not clear. The literature suggests both prohypertrophic and antihypertrophic effects of PKA. Furthermore, there are endogenous PKA inhibitors, PKI, highly expressed in the heart to regulate PKA activity but their roles in PCH have not been studied. We aim to explore the role of PKI/PKA in PCH induced by isoproterenol, phenylephrine, angiotensin II and pressure overload. Methods and Results: 1. PKIα and PKIγ were highly expressed in the heart but only PKIα was reduced by transaortic banding (TAB); TAB induced a significant increase in cardiac PKA activity at 1 week post TAB. 2. Four transgenic mouse lines with high (HE), medium (ME), low (LE) and very low (VLE) expression of PKI-GFP were obtained with the inhibition of maximum PKA activity induced by 1μM cAMP by 95%, 57%, 20% and 10% in the cardiac homogenates; 3. In the VLE hearts, some myocytes were PKI-GFP+ and some were PKI-GFP-, GFP- LVMs had significantly larger surface area than GFP+ LVMs; 4. PKA inhibition by PKI-GFP abolished PCH induced by isoproterenol, phenylephrine, angiotensin II in HE mice; 5. TAB for 8 weeks did not change HW/BW, myocyte cross-sectional area and myocardial fibrosis in HE mice but induced significant increases in HW/BW, myocyte cross-sectional area, myocardial fibrosis and depressed cardiac fractional shortening in control mice. 6. In cultured neonatal rat ventricular myocytes, PKI-GFP prevented myocyte hypertrophy induced by isoproterenol (ISO), phenylephrine (PE) and angiotensin II, as evidenced by no significant increases in protein synthesis (protein/DNA ratio), myocyte surface area, sarcomere organization. 7. PKI-GFP in NRVMs prevented the translocation of NFAT3 and HDAC5 induced by ISO and PE and increased the secretion of antihypertrophic ANF at baseline; 8. TAB induced PKA-dependent phosphorylation of GSK-3α and GSK-3β, inactivating them to relieve their antihypertrophic effect and promote protein synthesis (increased phosphorylation of mTORC1, eIF-4EBP1, p70 S6K); PKA inhibition abolished these effects. Conclusions: PKA is regulated by PKI and is a master regulator of PCH induced by pressure overload.

Myocardial hypertrophy reduces transmural variation in mitochondrial function.

Myocardial hypertrophy reduces transmural variation in mitochondrial function.

Oxidative activation of Ca2+/calmodulin-activated kinase II mediates ER stress-induced cardiac dysfunction and apoptosis

Endoplasmic reticulum (ER) stress elicits oxidative stress and intracellular Ca(2+) derangement via activation of Ca(2+)/calmodulin-dependent protein kinase II (CaMKII). This study was designed to examine the role of CaMKII in ER stress-induced cardiac dysfunction and apoptosis as well as the effect of antioxidant catalase. Wild-type FVB and transgenic mice with cardiac-specific overexpression of catalase were challenged with the ER stress inducer tunicamycin (3 mg/kg ip for 48 h). Presence of ER stress was verified using the ER stress protein markers immunoglobulin binding protein (BiP) and C/EBP homologous protein (CHOP), the effect of which was unaffected by catalase overexpression. Echocardiographic assessment revealed that tunicamycin elicited cardiac remodeling (enlarged end-systolic diameter without affecting diastolic and ventricular wall thickness), depressed fractional shortening, ejection fraction, and cardiomyocyte contractile capacity, intracellular Ca(2+) mishandling, accumulation of reactive oxygen species (superoxide production and NADPH oxidase p47phox level), CaMKII oxidation, and apoptosis (evidenced by Bax, Bcl-2/Bax ratio, and TUNEL staining), the effects of which were obliterated by catalase. Interestingly, tunicamycin-induced cardiomyocyte mechanical anomalies and cell death were ablated by the CaMKII inhibitor KN93, in a manner reminiscent of catalase. These data favored a permissive role of oxidative stress and CaMKII activation in ER stress-induced cardiac dysfunction and cell death. Our data further revealed the therapeutic potential of antioxidant or CaMKII inhibition in cardiac pathological conditions associated with ER stress. This research shows for the first time that contractile dysfunction caused by ER stress is a result of the oxidative activation of the CaMKII pathway.

Two Rare Human Mitofusin 2 Mutations Alter Mitochondrial Dynamics and Induce Retinal and Cardiac Pathology in Drosophila

Mitochondrial fusion is essential to organelle homeostasis and organ health. Inexplicably, loss of function mutations of mitofusin 2 (Mfn2) specifically affect neurological tissue, causing Charcot Marie Tooth syndrome (CMT) and atypical optic atrophy. As CMT-linked Mfn2 mutations are predominantly within the GTPase domain, we postulated that Mfn2 mutations in other functional domains might affect non-neurological tissues. Here, we defined in vitro and in vivo consequences of rare human mutations in the poorly characterized Mfn2 HR1 domain. Human exome sequencing data identified 4 rare non-synonymous Mfn2 HR1 domain mutations, two bioinformatically predicted as damaging. Recombinant expression of these (Mfn2 M393I and R400Q) in Mfn2-null murine embryonic fibroblasts (MEFs) revealed incomplete rescue of characteristic mitochondrial fragmentation, compared to wild-type human Mfn2 (hMfn2); Mfn2 400Q uniquely induced mitochondrial fragmentation in normal MEFs. To compare Mfn2 mutation effects in neurological and non-neurological tissues in vivo, hMfn2 and the two mutants were expressed in Drosophila eyes or heart tubes made deficient in endogenous fly mitofusin (dMfn) through organ-specific RNAi expression. The two mutants induced similar Drosophila eye phenotypes: small eyes and an inability to rescue the eye pathology induced by suppression of dMfn. In contrast, Mfn2 400Q induced more severe cardiomyocyte mitochondrial fragmentation and cardiac phenotypes than Mfn2 393I, including heart tube dilation, depressed fractional shortening, and progressively impaired negative geotaxis. These data reveal a central functional role for Mfn2 HR1 domains, describe organ-specific effects of two Mfn2 HR1 mutations, and strongly support prospective studies of Mfn2 400Q in heritable human heart disease of unknown genetic etiology.

Differential expression of potassium channels and abnormal conduction in experimental tachycardia-induced heart failure

Heart failure causes electrophysiological changes in the heart. Downregulation of repolarizing K+-currents leads to a prolongation of the cardiac action potential. Nevertheless, little is known about the differential expression of atrial and ventricular K+-channels in the failing heart. Ten rabbits underwent progressive rapid right ventricular pacing for 30days. Digitized ECGs and echocardiograms were obtained. Left ventricular and left atrial tissue was harvested and mRNA levels of BNP, Kv4.3, rERG, Kv1.5, and KvLQT1 were measured by real time PCR. Experimental heart failure was characterized by left ventricular dilatation (13 ± 1mm vs. 9 ± 1, p < .001), depressed fractional shortening (25 ± 5% vs. 40 ± 4, p < .001), and left atrial remodeling with increased diameter (16mm ± 2 vs. 12 ± 1, p = .002) and weight (1.3g ± 0.2 vs. 0.5 ± 0.1, p = .01). A prolongation of P-wave (44 ± 5ms vs. 40 ± 4, p = .001) and PQ-interval (73 ± 10ms vs. 66 ± 9, p = .009) occurred. In heart failure, BNP mRNA levels showed a significant upregulation in the left ventricle and atrium (1.83AU ±1.31 vs. 0.67 ± 0.65, p < .05 and 7.16AU ±1.76 vs. 0.77 ± 0.48, p < .05). Left ventricular Kv1.5 mRNA was reduced by 50% (p < .001) and KvLQT1 was reduced by 70% (p < .001). rERG and Kv4.3 mRNA were unchanged (n = ns). In contrast, left atrial Kv4.3 and KvLQT1 were reduced by 70% (p < .001), whereas rERG and Kv1.5 were unchanged (p = ns). Significant correlations were present between BNP and K+-channel expressions. Heart failure is characterized by significant changes in the gene expression of repolarizing K+-currents with a differential atrial and ventricular pattern. These molecular changes occur together with changes in cardiac function, geometry, conduction, and BNP expression and provide a functional basis for electrical vulnerability in heart failure.

Cigarette Smoke Exacerbates Ventricular Remodeling and Dysfunction in the Volume Overloaded Heart

Cigarette smoking is an independent risk factor for heart disease and is linked to sudden cardiac death. In this study, we examined the effects of cigarette smoke (CS) on the volume overload stressed heart. Our hypothesis was that CS exacerbates volume overload (VO)-induced cardiac dysfunction by accelerating ventricular remodeling. VO stress was surgically induced in male Sprague-Dawley rats by abdominal aortocaval fistula (ACF). Rats, with and without ACF, were exposed to either room air or CS (6 cigarettes/day) for 6 weeks. Temporal echocardiogram measurements indicated that CS significantly increased VO-induced left ventricular dilatation, prevented compensatory wall thickening, and depressed fractional shortening. Morphological analysis of ventricular collagen revealed that CS blunted compensatory collagen expression (45% decrease versus ACF alone). CS exacerbated the VO-induced increase of MMP-9 and TIMP-1 expression in the heart. CS also blocked the compensatory increases of HIF-1α, VEGF, and TGF-β in the VO-stressed heart. These data indicate that CS worsens VO remodeling by disrupting compensatory mechanisms, thereby promoting eccentric dilation and dysfunction.

Physiological homology betweenDrosophila melanogasterand vertebrate cardiovascular systems

SUMMARYThe physiology of the Drosophila melanogaster cardiovascular system remains poorly characterized compared with its vertebrate counterparts. Basic measures of physiological performance remain unknown. It also is unclear whether subtle physiological defects observed in the human cardiovascular system can be reproduced in D. melanogaster. Here we characterize the cardiovascular physiology of D. melanogaster in its pre-pupal stage by using high-speed dye angiography and optical coherence tomography. The heart has vigorous pulsatile contractions that drive intracardiac, aortic and extracellular-extravascular hemolymph flow. Several physiological measures, including weight-adjusted cardiac output, body-length-adjusted aortic velocities and intracardiac shear forces, are similar to those in the closed vertebrate cardiovascular systems, including that of humans. Extracellular-extravascular flow in the pre-pupal D. melanogaster circulation drives convection-limited fluid transport. To demonstrate homology in heart dysfunction, we showed that, at the pre-pupal stage, a troponin I mutant, held-up2 (hdp2), has impaired systolic and diastolic heart wall velocities. Impaired heart wall velocities occur in the context of a non-dilated phenotype with a mildly depressed fractional shortening. We additionally derive receiver operating characteristic curves showing that heart wall velocity is a potentially powerful discriminator of systolic heart dysfunction. Our results demonstrate physiological homology and support the use of D. melanogaster as an animal model of complex cardiovascular disease.

Concurrent Wheel Running and Weekly Doxorubicin Treatment in the Rat: Effects on Cardiac Function

The use of exercise as a means of battling cardiotoxicity associated with the chemotherapy drug doxorubicin is showing promise. However, questions regarding exercise's long-term protection against doxorubicin cardiotoxicity still remain. PURPOSE: To investigate the effects of concurrent voluntary wheel running and weekly doxorubicin treatment on cardiac function measured 10 or 16 weeks after treatment. METHODS: Female rats were randomly assigned to the doxorubicin group (DOX) or the control group (CON). Animals in DOX received 2.5 mg·kg-1 doxorubicin weekly for 6 weeks (15 mg·kg-1 cumulative), and animals in CON received saline injections weekly for 6 weeks. DOX and CON animals were then assigned to either wheel running (W+DOX or W+CON, respectively) or sedentary (S+DOX and S+CON, respectively) groups. W+DOX and W+CON were introduced to voluntary wheel running cages following the first injection and were allowed 24 hour per day access to the running wheels for 10 weeks (10w) or 16 weeks (16w). S+DOX and S+CON were confined to normal cage activity for 10w or 16w. Cardiac function was then assessed at 10w or 16w. RESULTS: At 10w, S+DOX had a significantly depressed fractional shortening (FS) when compared to S+CON (-25%, p<0.05), but W+DOX FS did not differ significantly from S+CON at 10w (-11%, p>0.05). S+DOX and W+DOX possessed lower maximal mitral blood flow velocities (MVmax, -53% and -33%, respectively, p<0.05) and maximal aortic blood flow velocities (AVmax, -48% and -25%, respectively, p<0.05) than S+SAL at 10w; however, MVmax and AVmax were significantly greater in W+DOX than S+DOX (p<0.05). At 16w, S+DOX had an 18% decline in FS and W+DOX had a 7% decline in FS when compared to S+CON, but these differences were not significant (p>0.05). S+DOX had a significantly reduced MVmax and AVmax when compared to S+CON at 16w (-41% and -38%, respectively, p<0.05), but W+DOX MVmax and AVmax was not found to differ from S+CON (-12% and -5%, respectively, p>0.05). CONCLUSIONS: Wheel running during and following 6 weeks of doxorubicin treatment provided cardioprotection which lasted 16 weeks.

Gender Differences in Cardiac Dysfunction and Remodeling due to Volume Overload

Background This study examined the sex differences for hemodynamic and echocardiographic changes in hypertrophied and failing hearts induced by arteriovenous (AV) shunt. Methods and Results Echocardiographic and hemodynamic alterations were determined in male and female rats at 4 and 16 weeks after AV shunt. Ovariectomized females treated with estrogen for 16 weeks post-AV shunt were also used. Both genders developed cardiac hypertrophy at 4 and 16 weeks post-AV shunt; however, the increase in cardiac muscle mass was greater in females than males at 16 weeks. At 4 weeks post-AV shunt, increases in ventricular dimensions and left ventricular end-diastolic pressure (LVEDP) as well as a decrease in fractional shortening occurred in males only. Unlike the females, the rates of pressure development (+dP/dt) and decay (-dP/dt) were depressed and LVEDP increased in male rats at 16 weeks post-AV shunt. An increase in cardiac output was seen in both genders, but this was more marked in the males at 4 and 16 weeks post-AV shunt. Although mRNA levels for ACE were increased in both male and female rats at 4 and 16 weeks, mRNA levels for angiotensin II type 1 receptor were increased in males at 16 weeks only. Furthermore, increases in plasma catecholamines were elevated in males but were decreased or unchanged in females at 16 weeks of AV shunt. LV internal diameters as well as depressed fractional shortening occurred in males whereas increases in posterior wall thickness were seen in the female rats at 16 weeks of AV shunt. Ovariectomy resulted in depressed +dP/dt, -dP/dt, and fractional shortening, whereas a marked increase in cardiac output as well as increased LVEDP and LV internal diameters were observed at 16 weeks post-AV shunt. Although treatment with 17-β estradiol normalized ±dP/dt, LVEDP remained elevated. Conclusion Gender differences in cardiac function may be due to differences in the type of cardiac remodeling as a consequence of AV shunt. Furthermore, estrogen appears to play an important role in preventing cardiac dysfunction and adverse ventricular remodeling in female rats.

Anandamide Preserves Cardiac Function and Geometry in an Acute Doxorubicin Cardiotoxicity Rat Model

We investigated the use of the endocannabinoid anandamide as a means of cardioprotection against doxorubicin-induced cardiac dysfunction. Male rats received doxorubicin with or without anandamide pretreatment. Cardiac function was assessed in vivo using transthoracic echocardiography and ex vivo using the isolated working heart 5 days posttreatment. Doxorubicin administration without anandamide pretreatment resulted in a decline in fractional shortening (P < .05) and left ventricular wall thickness when compared to controls (P < .05). Ex vivo cardiac function analysis revealed a reduction in left ventricular developed pressure in hearts from animals receiving doxorubicin without anandamide pretreatment when compared to controls (P < .05). Left ventricles from animals receiving anandamide pretreatment before doxorubicin administration did not exhibit depressed fractional shortening, ventricular wall thickness, or developed pressure when compared to controls (P > .05). These results suggest that a potential therapy for doxorubicin-induced cardiotoxicity involves targeting the endogenous cannabinoid system.

Bitransgenesis with β2‐Adrenergic Receptors or Adenylyl Cyclase Fails to Improve β1‐Adrenergic Receptor Cardiomyopathy

Cardiomyopathic effects of beta-adrenergic receptor (betaAR) signaling are primarily due to the beta(1)AR subtype. beta(1)/beta(2)AR and beta(1)/adenylyl cyclase type 5 (AC5) bitransgenic mice were created to test the hypothesis that beta(2)AR or AC5 co-overexpression has beneficial effects in beta(1)AR-mediated cardiomyopathy. In young mice, beta(1)/beta(2) hearts had a greater increase in basal and isoproterenol-stimulated contractility compared to beta(1)/AC5 and beta(1)AR hearts. By 6 months, beta(1)AR and beta(1)/beta(2) hearts retained elevated basal contractility but were unresponsive to agonist. In contrast, beta(1)/AC5 hearts maintained a small degree of agonist responsiveness, which may be due to a lack of beta(1)AR downregulation that was noted in beta(1)- and beta(1)/beta(2) hearts. However, by 9 -months, beta(1), beta(1)/beta(2), and beta(1)/AC5 mice had all developed severely depressed fractional shortening in vivo and little response to agonist. p38 mitogen activated protein kinase (MAPK) was minimally activated by beta(1)AR, but was markedly enhanced in the bitransgenics. Akt activation was only found with the bitransgenics. The small increase in cystosolic second mitochondria-derived activator of caspase (Smac), indicative of apoptosis in 9-month beta(1)AR hearts, was suppressed in beta(1)/AC5, but not in beta(1)/beta(2), hearts. Taken together, the unique signaling effects of enhanced beta(2)AR and AC5, which have the potential to afford benefit in heart failure, failed to salvage ventricular function in beta(1)AR-mediated cardiomyopathy.

Abstract 4956: A Risk Stratification Analysis of Predictors of Death or Transplant in Children with Hypertrophic Cardiomyopathy

We previously reported initial results from a univariate analysis of baseline predictors of death or heart transplant in children with hypertrophic cardiomyopathy (HCM). We present here the final multivariate analysis resulting in risk stratification rules for 6 HCM etiologic subgroups in children. The Pediatric Cardiomyopathy Registry collected longitudinal data on 882 children with HCM from 1990 –2003. The primary outcome was the earlier of death or heart transplantation. Cox regression was used to identify the 3 most important risk factors at time of diagnosis for each HCM subgroup; all echo measures were expressed as z-scores. Multivariate analysis revealed that children with idiopathic HCM diagnosed by 1 year were at higher risk of poor outcome if they had CHF, low BSA, or elevated LV mass, while risk factors for children diagnosed after 1 year were female gender, depressed fractional shortening, and elevated wall thickness. Risk factors for children with malformation syndrome were Black race, CHF and increased wall thickness; Black race, younger age, and elevated LV mass for children with inborn errors of metabolism; younger age, CHF, and increased wall thickness for children with mixed restrictive HCM; and decreased weight, family history of heart disease, and increased wall thickness for children with mixed dilated HCM. Children with multiple risk factors present at diagnosis had a significantly worse prognosis compared to those with 0 or 1 risk factors. (Figure ) Based on etiologic subtype and number of risk factors present at diagnosis, clinicians can reliably estimate the risk of death of transplant in children with HCM.

The Efficacy of Mitral Valve Surgery in Children with Dilated Cardiomyopathy and Severe Mitral Regurgitation

Severe mitral regurgitation predicts poor outcomes in adults with left ventricular dysfunction. Frequently, adult patients now undergo initial mitral valve surgery instead of heart transplant. Pediatric data are limited. This study evaluates the efficacy of mitral valve surgery for severe mitral regurgitation in children with dilated cardiomyopathy. This is a single-institution experience in seven children (range, 0.5-10.9 years) with severe mitral regurgitation and dilated cardiomyopathy who underwent mitral valve surgery between January 1988 and February 2005, with follow-up to January 2006. Children with dilated cardiomyopathy had a depressed fractional shortening preoperatively (24.4% +/- 6.1%) that remained depressed (22.9% +/- 7.6%) 1.3 +/- 1.2 years after surgery (p = 0.50). Left ventricular end-diastolic (6.5 +/- 1.5 to 4.8 +/- 1.8 z-scores, p < 0.01) and end-systolic (6.8 +/- 1.5 to 5.5 +/- 2.1 z-scores, p < 0.05) dimensions improved. Hospitalization frequency had a median decrease of 6.0 hospitalizations per year (p < 0.02). Three patients were transplanted 0.2, 2.4, and 3.5 years after surgery. There was no perioperative mortality. Mitral valve surgery in children with dilated cardiomyopathy was performed safely and improved symptoms, stabilizing ventricular dysfunction in most patients. Mitral valve surgery should be considered prior to heart transplant in children with dilated cardiomyopathy and severe mitral regurgitation.

Prospective Familial Assessment in Dilated Cardiomyopathy

In autoimmune disorders, circulating autoantibodies identify healthy relatives at risk years before clinical presentation. Healthy relatives of patients with dilated cardiomyopathy (DCM) who have echocardiographic changes, including left ventricular enlargement or depressed fractional shortening at baseline, have increased medium-term risk for DCM development. Approximately one third of relatives have serum anti-heart autoantibodies (AHAs) at baseline; we intended to assess their potential role in predicting DCM development. Baseline evaluation, including electrocardiography, echocardiography, and AHA, was performed in 592 asymptomatic relatives of 169 consecutive DCM patients (291 males and 301 females; mean age 36+/-16 years). Relatives were classified in accordance with published echocardiographic criteria; those who did not have DCM were followed up (median of 58 months). DCM among relatives was diagnosed by echocardiography at follow-up. Of the 592 individuals evaluated, 77% were assessed as normal, 4.4% as having DCM, and 19% as possibly affected on the basis of depressed fractional shortening without ventricular dilatation in 17 and left ventricular enlargement without systolic dysfunction in 94. Five-year follow-up of 311 relatives revealed that 26 had progressed (13 to DCM, 11 to left ventricular enlargement, and 2 to depressed fractional shortening). Relatives who developed DCM were more frequently AHA-positive than those who did not (69% versus 37%, P=0.02). Five-year probability of progression to DCM, among normal or possibly affected relatives, was higher in AHA-positive cases (P=0.03). By Cox regression, positive AHAs at baseline were independent predictors of progression (RR 2.26, CI 1 to 5.1, P=0.03). Among healthy relatives of DCM patients, AHAs are independent predictors of disease development within 5 years.

Neonatal Surgical Aortic Commissurotomy: Predictors of Outcome and Long-Term Results

The objective of this study was to review our institutional experience concerning neonatal aortic commissurotomy and to identify predictors of outcome. From January 1, 1990, to January 1, 2005, 65 neonates were referred for critical aortic stenosis. Among these 36 consecutive patients underwent surgical valvotomy by the same surgeon and 16 patients had balloon valvotomy. We examined clinical records to establish determinants of outcome and illustrate long-term results. In the surgical group 6 patients had nonstenotic parachute mitral valve, 6 had aortic coarctation, 13 had endocardial fibroelastosis; and 15 had depressed fractional shortening. In the balloon valvotomy group most infants had associated mitral stenosis (n = 7), small aortic annulus (n = 5), multiple anomalies (n = 2), endocardial fibroelastosis (n = 9), and depressed fractional shortening (n = 13). In the surgical group global mortality was 19%; 47% in infants with depressed fractional shortening and 0% in infants with normal fractional shortening. Mortality in the balloon valvotomy group was 56%. Low fractional shortening, low mean aortic gradient, endocardial fibroelastosis, and small aortic annulus were associated with fatal outcome. In the surgical group 6 patients needed Ross operation at a median interval of 4 years from commissurotomy. In the balloon valvotomy group 3 patients needed early mitral replacement and 5 aortic valve surgery. At a median follow-up of 6 years, all children are in New York Heart Association class I, all have a normal ventricular function, 2 have aortic restenosis, and 5 have at least moderate aortic incompetence. In a selected population of neonates with isolated aortic stenosis, surgical valvotomy offers an excellent long-term outcome to patients with a normokinetic left ventricle, while patients with a hypokinetic left ventricle have a poor outcome. Balloon valvotomy offers poor results when performed in patients with complex anomalies.

Echocardiographic Evaluation in Asymptomatic Relatives of Patients with Dilated Cardiomyopathy Reveals Preclinical Disease

Idiopathic dilated cardiomyopathy is often familial, and apparently healthy relatives may have latent, early, or undiagnosed established disease. To determine the prevalence and natural history of asymptomatic cardiac abnormalities among sampled relatives of unselected patients referred for management of dilated cardio-myopathy. Prospective cohort study. 767 asymptomatic relatives of 189 consecutive unselected patients with dilated cardiomyopathy. Clinical evaluation, including history, physical examination, electrocardiography, and echocardiography, was performed. Participants were classified in accordance with published echocardiographic criteria. Sampled relatives who did not have evidence of dilated cardiomyopathy at the initial evaluation were followed for a median of 57 months (range, 1 to 133 months). Of the 767 patients evaluated, 592 (77.2%) were assessed as healthy, 35 (4.6% [95% CI, 3.7% to 7.6%]) had dilated cardiomyopathy, 119 (15.5% [CI, 12.5% to 18.8%]) had left ventricular enlargement without systolic dysfunction, and 21 (2.7% [CI, 1.9% to 4.9%]) had depressed fractional shortening without ventricular dilatation. At follow-up, progression to dilated cardiomyopathy occurred in 13 (10%) relatives with left ventricular enlargement or depressed fractional shortening versus 3 (1.3%) healthy relatives. In a multivariate model, only left ventricular enlargement or depressed fractional shortening independently predicted progression to dilated cardiomyopathy (hazard ratio, 10.0 [CI, 2.8 to 35.5]; P < 0.001). Because relatives had to be willing to participate and be available geographically, selection bias may have occurred. Treatable asymptomatic dilated cardiomyopathy was identified in 4.6% of asymptomatic relatives. In addition, left ventricular enlargement and depressed fractional shortening were common in asymptomatic relatives of patients with dilated cardiomyopathy and were associated with a statistically significant medium-term risk for disease progression. Evaluation of relatives of patients with cardiomyopathy is recommended.

Regulation of myocardial function by histidine-rich, calcium-binding protein.

Impaired sarcoplasmic reticulum (SR) Ca release has been suggested to contribute to the depressed cardiac function in heart failure. The release of Ca from the SR may be regulated by the ryanodine receptor, triadin, junctin, calsequestrin, and a histidine-rich, Ca-binding protein (HRC). We observed that the levels of HRC were reduced in animal models and human heart failure. To gain insight into the physiological function of HRC, we infected adult rat cardiac myocytes with a recombinant adenovirus that contains the full-length mouse HRC cDNA. Overexpression (1.7-fold) of HRC in adult rat cardiomyocytes was associated with increased SR Ca load (28%) but decreased SR Ca-induced Ca release (37%), resulting in impaired Ca cycling and depressed fractional shortening (36%) as well as depressed rates of shortening (38%) and relengthening (33%). Furthermore, the depressed basal contractile and Ca kinetic parameters in the HRC-infected myocytes remained significantly depressed even after maximal isoproterenol stimulation. Interestingly, HRC overexpresssion was accompanied by increased protein levels of junctin (1.4-fold) and triadin (1.8-fold), whereas the protein levels of ryanodine receptor, calsequestrin, phospholamban, and sarco(endo)plasmic reticulum Ca-ATPase remained unaltered. Collectively, these data indicate that alterations in expression levels of HRC are associated with impaired cardiac SR Ca homeostasis and contractile function.

Effects of angiotensin II receptor blockade versus angiotensin-converting-enzyme inhibition on ventricular remodelling following myocardial infarction in the mouse

Left ventricular (LV) remodelling following myocardial infarction (MI) is associated with increased morbidity and mortality. Previous data suggest that angiotensin II (Ang II) plays a central role in the molecular events contributing to LV remodelling. We explored the effects of angiotensin-converting-enzyme (ACE) inhibition versus Ang II (AT1) receptor blockade on LV remodelling in mice post-MI. Mice underwent sham procedure or left coronary artery ligation, and received placebo, the AT1 receptor antagonist, losartan or the ACE inhibitor, enalapril. At 6 weeks, echocardiography and haemodynamic studies were performed. Infarct size and interstitial collagen content were determined. Expression of genes encoding atrial natriuretic peptide (ANP), collagen type I, AT1a and AT1b receptors were measured. The placebo MI group showed increased LV end-diastolic diameter, LV end-systolic diameter with depressed fractional shortening (P&lt;0.01 versus shams), increased LV mass and volume (both P&lt;0.01 versus shams). The placebo MI group also exhibited increased non-infarct zone collagen content (P&lt;0.01), ANP (P&lt;0.01) and collagen type 1 (P&lt;0.01) gene expression, with a non-significant rise in AT1a receptor gene expression. Neither losartan or enalapril prevented LV dilation or improved fractional shortening. Both similarly lowered systolic blood pressure (P&lt;0.01 for each versus placebo). Losartan and enalapril inhibited LV hypertrophy (P&lt;0.01), and decreased ANP (P&lt;0.01) and collagen type 1 gene expression (P&lt;0.05). Levels of AT1a receptor gene expression were higher than shams (P&lt;0.05 for both), but similar to placebo. AT1b receptor gene expression was much lower than that for AT1a receptor and similar in all groups. Thus, in this model, AT1 receptor antagonism and ACE inhibition have equivalent inhibitory effects on myocardial hypertrophy and fibrosis. These results serve as an important basis for planned investigations to evaluate the anti-remodelling effects of these agents on mice in which genetic manipulations are used to disrupt components of the Ang II signalling system.