Estimation of cardiac reserve by peak power: validation and initial application of a simplified index.
(65/2423)
OBJECTIVES: To validate a simplified estimate of peak power (SPP) against true (invasively measured) peak instantaneous power (TPP), to assess the feasibility of measuring SPP during exercise and to correlate this with functional capacity. DESIGN: Development of a simplified method of measurement and observational study. SETTING: Tertiary referral centre for cardiothoracic disease. SUBJECTS: For validation of SPP with TPP, seven normal dogs and four dogs with dilated cardiomyopathy were studied. To assess feasibility and clinical significance in humans, 40 subjects were studied (26 patients; 14 normal controls). METHODS: In the animal validation study, TPP was derived from ascending aortic pressure and flow probe, and from Doppler measurements of flow. SPP, calculated using the different flow measures, was compared with peak instantaneous power under different loading conditions. For the assessment in humans, SPP was measured at rest and during maximum exercise. Peak aortic flow was measured with transthoracic continuous wave Doppler, and systolic and diastolic blood pressures were derived from brachial sphygmomanometry. The difference between exercise and rest simplified peak power (Delta SPP) was compared with maximum oxygen uptake (VO(2)max), measured from expired gas analysis. RESULTS: SPP estimates using peak flow measures correlated well with true peak instantaneous power (r = 0.89 to 0.97), despite marked changes in systemic pressure and flow induced by manipulation of loading conditions. In the human study, VO(2)max correlated with Delta SPP (r = 0.78) better than Delta ejection fraction (r = 0.18) and Delta rate-pressure product (r = 0.59). CONCLUSIONS: The simple product of mean arterial pressure and peak aortic flow (simplified peak power, SPP) correlates with peak instantaneous power over a range of loading conditions in dogs. In humans, it can be estimated during exercise echocardiography, and correlates with maximum oxygen uptake better than ejection fraction or rate-pressure product. (+info)
Graft coronary artery disease is strongly related to the aetiology of heart failure and cellular rejections.
(66/2423)
AIMS: To identify risk factors for the development of coronary artery disease after heart transplantation. METHODS AND RESULTS: In consecutive heart transplanted patients, who underwent coronary angiography at the first year follow-up, the aetiology of heart failure in 113 was ischaemic heart disease or dilated cardiomyopathy. Development of clinically significant graft coronary artery disease was analysed vs recipient and donor pre- and post-transplantation variables. At 1, 5 and 9 years follow-up, coronary artery disease had developed in 4%, 16%, and 20% of the included patients, respectively. Among patients with ischaemic heart disease as the aetiology of heart failure, 38% developed graft coronary artery disease, while the corresponding figure for patients with dilated cardiomyopathy was 9% (P<0.001) during 9 years of follow-up. In multivariate regression analysis, the aetiology of ischaemic heart disease and the number of cellular rejections were independent predictors of developing graft coronary artery disease, with risk ratios of 5.8, (95% confidence interval of 2.2-14.8 (P=0.0003)) and 3.3, (95% confidence interval of 1.7-6.5 (P=0.0004)), respectively. Classical risk factors for coronary artery disease did not influence the development of graft coronary artery disease. CONCLUSIONS: Ischaemic heart disease as the aetiology of heart failure and the number of cellular rejections were powerful independent predictors of development of graft coronary artery disease following heart transplantation. The low incidence of graft coronary artery disease among patients with dilated cardiomyopathy implies that coronary angiography after heart transplantation can be made on a more selective basis. (+info)
Intensity of myocardial expression of inducible nitric oxide synthase influences the clinical course of human immunodeficiency virus-associated cardiomyopathy. Gruppo Italiano per lo Studio Cardiologico dei pazienti affetti da AIDS (GISCA).
(67/2423)
BACKGROUND: Increased levels of tumor necrosis factor-alpha (TNF-alpha) and inducible nitric oxide synthase (iNOS) have been reported in patients with dilated cardiomyopathy. We investigated the myocardial expression of TNF-alpha and iNOS in patients with HIV-associated cardiomyopathy (HIV-DCM) compared with patients with idiopathic dilated cardiomyopathy (IDCM). METHODS AND RESULTS: Endomyocardial biopsy specimens from 82 HIV-DCM and 80 IDCM patients were processed for determination of the immunostaining intensity of TNF-alpha and iNOS and for virological examination. Negative controls were derived from autopsy myocardium specimens from 32 HIV-negative patients without known heart disease. The mortality rate for congestive heart failure between groups according to the intensity of iNOS staining was also evaluated. The mean intensity of both TNF-alpha and iNOS staining was greater in patients with HIV-DCM (0.81 and 1.007, respectively) than in patients with IDCM (0.44 and 0.49, respectively) and controls (0.025 and 0.027, respectively). The staining intensity of both TNF-alpha and iNOS was inversely correlated with CD4 count. The staining intensity of iNOS was greater in HIV-DCM patients with HIV/coxsackievirus B3 (CVB3) or with HIV/cytomegalovirus coinfection than in IDCM patients showing infection with CVB3 and adenovirus alone. The staining intensity of iNOS correlated to mortality rate, because it was higher in HIV-DCM patients and, in particular, in those with an optical density unit >1. CONCLUSIONS: Cytokine activation seems to play a significant pathogenetic role in both HIV-DCM and IDCM. In HIV-DCM patients, the state of immunodeficiency may favor the selection of viral variants of increased pathogenicity, influencing the clinical course of cardiomyopathy by enhancement of the inflammatory process. (+info)
Disruption of the sarcoglycan-sarcospan complex in vascular smooth muscle: a novel mechanism for cardiomyopathy and muscular dystrophy.
(68/2423)
To investigate mechanisms in the pathogenesis of cardiomyopathy associated with mutations of the dystrophin-glycoprotein complex, we analyzed genetically engineered mice deficient for either alpha-sarcoglycan (Sgca) or delta-sarcoglycan (Sgcd). We found that only Sgcd null mice developed cardiomyopathy with focal areas of necrosis as the histological hallmark in cardiac and skeletal muscle. Absence of the sarcoglycan-sarcospan (SG-SSPN) complex in skeletal and cardiac membranes was observed in both animal models. Loss of vascular smooth muscle SG-SSPN complex was only detected in Sgcd null mice and associated with irregularities of the coronary vasculature. Administration of a vascular smooth muscle relaxant prevented onset of myocardial necrosis. Our data indicate that disruption of the SG-SSPN complex in vascular smooth muscle perturbs vascular function, which initiates cardiomyopathy and exacerbates muscular dystrophy. (+info)
Clinical profiles of four large pedigrees with familial dilated cardiomyopathy: preliminary recommendations for clinical practice.
(69/2423)
OBJECTIVES: This study aimed to characterize the clinical profile of familial dilated cardiomyopathy (FDC) in the families of four index patients initially diagnosed with idiopathic dilated cardiomyopathy (IDC) and to provide clinical practice recommendations for physicians dealing with these diseases. BACKGROUND: Recent evidence indicates that approximately one-half of patients diagnosed with IDC will have FDC, a genetically transmissible disease, but the clinical profile of families screened for FDC in the U.S. has not been well documented. Additionally, recent ethical guidelines suggest increased responsibilities in caring for patients with newly found genetic cardiovascular disease. METHODS: After identification of four families with FDC, we undertook clinical screening including medical history, physical examination, electrocardiogram and echocardiogram. Diagnostic criteria for FDC-affected status of asymptomatic family members was based on left ventricular enlargement (LVE). Subjects with confounding cardiovascular diagnoses or body mass indices >35 were excluded. RESULTS: We identified 798 living members from the four FDC pedigrees, and screened 216 adults and 129 children (age <16 years). Twenty percent of family members were found to be affected with FDC; 82.8% of those affected were asymptomatic. All four pedigrees demonstrated autosomal dominant patterns of inheritance. The average left ventricular end-diastolic dimension was 61.4 mm for affected and 48.4 mm for unaffected subjects, with an average age of 38.3 years (+/- 14.6 years) for affected and 32.1 years for unaffected subjects. The age of onset for FDC varied considerably between and within families. Presenting symptoms when present were decompensated heart failure or sudden death. CONCLUSIONS: We propose that with a new diagnosis of IDC, a thorough family history for FDC should be obtained, followed by echocardiographic-based screening of first-degree relatives for LVE, assuming their voluntary participation. If a diagnosis of FDC is established, we suggest further screening of first-degree relatives, and all subjects with FDC undergo medical treatment following established guidelines. Counseling of family members should emphasize the heritable nature of the disease, the age-dependent penetrance and the unpredictable clinical course. (+info)
Investigation of a family with autosomal dominant dilated cardiomyopathy defines a novel locus on chromosome 2q14-q22.
(70/2423)
Dilated cardiomyopathy (DCM) is a leading cause of heart failure and the most frequent indication for heart transplantation in young patients. Probably >25% of DCM cases are of familial etiology. We report here genetic localization in a three-generation German family with 12 affected individuals with autosomal dominant familial DCM characterized by ventricular dilatation, impaired systolic function, and conduction disease. After exclusion of known DCM loci, we performed a whole-genome screen and detected linkage of DCM to chromosome 2q14-q22. Investigation of only affected individuals defines a 24-cM interval between markers D2S2224 and D2S2324; when unaffected individuals are also included, the critical region decreases to 11 cM between markers D2S2224 and D2S112, with a peak LOD score of 3.73 at recombination fraction 0 at D2S2339. The identification of an additional locus for familial autosomal dominant DCM underlines the genetic heterogeneity and may assist in the elucidation of the causes of this disease. (+info)
Beta-adrenergic receptor blockade arrests myocyte damage and preserves cardiac function in the transgenic G(salpha) mouse.
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Transgenic (TG) mice with cardiac G(salpha) overexpression exhibit enhanced inotropic and chronotropic responses to sympathetic stimulation, but develop cardiomyopathy with age. We tested the hypothesis that cardiomyopathy in TG mice with G(salpha) overexpression could be averted with chronic beta-adrenergic receptor (beta-AR) blockade. TG mice and age-matched wild-type littermates were treated with the beta-AR blocker propranolol for 6-7 months, starting at a time when the cardiomyopathy was developing but was not yet severe enough to induce significant cardiac depression (9.5 months of age), and ending at a time when cardiac depression and cardiomyopathy would have been clearly manifest (16 months of age). Propranolol treatment, which can induce cardiac depression in the normal heart, actually prevented cardiac dilation and the depressed left ventricular function characteristic of older TG mice, and abolished premature mortality. Propranolol also prevented the increase in myocyte cross-sectional area and myocardial fibrosis. Myocyte apoptosis, already apparent in 9-month-old TG mice, was actually eliminated by chronic propranolol. This study indicates that chronic sympathetic stimulation over an extended period is deleterious and results in cardiomyopathy. Conversely, beta-AR blockade is salutary in this situation and can prevent the development of cardiomyopathy. (+info)
Natriuretic peptides in patients with diastolic dysfunction due to idiopathic dilated cardiomyopathy.
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AIMS: The degree of systolic dysfunction does not always correlate with functional impairment in patients with congestive heart failure. In contrast, diastolic dysfunction correlates well with functional impairment. In heart failure, both elevation of N-terminal proatrial natriuretic peptide and B-type natriuretic peptide are markers of a poor prognosis. METHODS: We investigated 32 patients (26 male, 6 female; mean age 55+/-2 years) with dilated cardiomyopathy and sinus rhythm. M-mode echocardiography and 2D-echocardiography were carried out in each patient. Pulsed-wave Doppler inflow signals were obtained and the following parameters were measured: maximal E wave and maximal A wave velocity, E/A ratio, E wave deceleration time, A wave deceleration time. Immediately after echocardiography blood samples were collected from patients in the supine position. N-terminal proANP and brain natriuretic peptide were measured using a radioimmuno assay. RESULTS: The left ventricular ejection fraction was 34+/-1%, the left ventricular end-diastolic diameter on M-mode echocardiography was 68+/-1 mm, while left atrial diameter was 45+/-1 mm. Univariate analysis revealed a significant correlation between both left atrial diameter and ejection fraction and N-terminal proANP and brain natriuretic peptide. All transmitral Doppler parameters showed a significant correlation with N-terminal proANP and brain natriuretic peptide. On forward stepwise regression analysis, left atrial diameter and ejection fraction were able to predict both N-terminal proANP and brain natriuretic peptide. However, of the diastolic parameters only the E/A ratio remained significant. Mildly symptomatic patients differed significantly from severely symptomatic patients in all Doppler parameters. Mildly symptomatic patients had significantly lower levels of N-terminal proANP (0.571+/-0.079 vs 2.282+/-0.340 nmol. l(-1);P<0.001) and brain natriuretic peptide (51+/-14.8 vs 474.2+/- 86.8 pg. ml(-1);P<0. 001). CONCLUSION: There is a close relationship between natriuretic peptides and diastolic Doppler parameters of left ventricular filling in patients with dilated cardiomyopathy. There is also a significant difference between patients with mild and severe functional impairment regarding both natriuretic peptides and transmitral Doppler parameters. (+info)