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1.
J Artif Organs ; 20(3): 266-269, 2017 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-28349221

RESUMO

Idiopathic hypereosinophilic syndrome is a condition of unknown etiology characterized by proliferation of eosinophils and their infiltration into tissues. Although cardiac involvement is rare, eosinophilic myocarditis can lead to life-threating fulminant congestive heart failure. Treatment of patients with eosinophilic myocarditis is challenging as heart failure can be caused by biventricular dysfunction. To our knowledge, this is the first case reported in the literature describing a patient with acute severe biventricular heart failure caused by eosinophilic myocarditis with mural left ventricular apical thrombus who was successfully treated with implantation of a total artificial heart as a bridge to heart transplant.


Assuntos
Eosinofilia/complicações , Insuficiência Cardíaca/cirurgia , Ventrículos do Coração/fisiopatologia , Coração Artificial , Miocardite/complicações , Biópsia , Ecocardiografia , Eosinofilia/diagnóstico , Insuficiência Cardíaca/diagnóstico , Insuficiência Cardíaca/etiologia , Ventrículos do Coração/diagnóstico por imagem , Ventrículos do Coração/cirurgia , Humanos , Masculino , Miocardite/diagnóstico , Miocárdio/patologia , Tomografia Computadorizada por Raios X , Adulto Jovem
2.
Curr Cardiol Rep ; 18(11): 108, 2016 11.
Artigo em Inglês | MEDLINE | ID: mdl-27628294

RESUMO

Cardiovascular disease has been responsible for more deaths in women than in men each year since 1985. This review discusses federal laws that have influenced the inclusion of women in research and reporting sex-specific differences, then addresses gender differences and gender disparities in four areas of clinical cardiovascular medicine: coronary heart disease, valvular heart disease, electrophysiology, and heart failure. The prevalence of disease in women is highlighted, the clinical characteristics of women at the time of referral for advanced therapies are reviewed, and the clinical outcomes of women are discussed. With the emergence of new technology such as smaller devices and less invasive procedures, more women are being referred for advanced therapies. However, a gap in awareness and diagnosis remains, contributing to later referrals for women. Women who do undergo advanced therapies often have more comorbidities and worse outcomes than men. A call is made to increase awareness, educate healthcare providers, and report more sex-specific data to resolve these gender disparities.


Assuntos
Eletrofisiologia Cardíaca/estatística & dados numéricos , Doença da Artéria Coronariana/diagnóstico , Insuficiência Cardíaca/diagnóstico , Doenças das Valvas Cardíacas/diagnóstico , Encaminhamento e Consulta/estatística & dados numéricos , Caracteres Sexuais , Saúde da Mulher , Doença da Artéria Coronariana/fisiopatologia , Diagnóstico Tardio , Feminino , Disparidades nos Níveis de Saúde , Disparidades em Assistência à Saúde/estatística & dados numéricos , Insuficiência Cardíaca/fisiopatologia , Doenças das Valvas Cardíacas/fisiopatologia , Humanos , Masculino , Prevalência , Fatores Sexuais
3.
Transplantation ; 97(6): 708-14, 2014 Mar 27.
Artigo em Inglês | MEDLINE | ID: mdl-24637869

RESUMO

BACKGROUND: Gene expression profiling test scores have primarily been used to identify heart transplant recipients who have a low probability of rejection at the time of surveillance testing. We hypothesized that the variability of gene expression profiling test scores within a patient may predict risk of future events of allograft dysfunction or death. METHOD: Patients from the IMAGE study with rejection surveillance gene expression profiling tests performed at 1- to 6-month intervals were selected for this cohort study. Gene expression profiling score variability was defined as the standard deviation of an individual's cumulative test scores. Gene expression profiling ordinal score (range, 0-39), threshold score (binary value=1 if ordinal score ≥ 34), and score variability were studied in multivariate Cox regression models to predict future clinical events. RESULTS: Race, age at time of transplantation, and time posttransplantation were significantly associated with future events in the univariate analysis. In the multivariate analyses, gene expression profiling score variability, but not ordinal scores or scores over threshold, was independently associated with future clinical events. The regression coefficient P values were <0.001, 0.46, and 0.773, for gene expression profiling variability, ordinal, and threshold scores, respectively. The hazard ratio for a 1 unit increase in variability was 1.76 (95% CI, 1.4-2.3). DISCUSSION: The variability of a heart recipient's gene expression profiling test scores over time may provide prognostic utility. This information is independent of the probability of acute cellular rejection at the time of testing that is rendered from a single ordinal gene-expression profiling test score.


Assuntos
Perfilação da Expressão Gênica , Testes Genéticos , Rejeição de Enxerto/genética , Transplante de Coração/efeitos adversos , Adulto , Idoso , Biópsia , Feminino , Perfilação da Expressão Gênica/métodos , Predisposição Genética para Doença , Testes Genéticos/métodos , Rejeição de Enxerto/patologia , Transplante de Coração/mortalidade , Humanos , Masculino , Pessoa de Meia-Idade , Análise Multivariada , Valor Preditivo dos Testes , Modelos de Riscos Proporcionais , Fatores de Risco , Fatores de Tempo , Resultado do Tratamento , Estados Unidos
4.
Tex Heart Inst J ; 39(4): 554-6, 2012.
Artigo em Inglês | MEDLINE | ID: mdl-22949777

RESUMO

We report the case of a patient who had chronic anthracycline-induced cardiomyopathy that was reversed after treatment with a left ventricular assist device. A 29-year-old woman had undergone anthracycline-based chemotherapy as a teenager in 1991 and 1992 and received a diagnosis of dilated cardiomyopathy 10 years later. Optimal medical therapy had initially controlled the symptoms of heart failure. However, in June 2006, the symptoms worsened to New York Heart Association functional class IV status. We implanted a continuous-flow left ventricular assist device as a bridge to cardiac transplantation; of note, a left ventricular core biopsy at that time showed no replacement fibrosis. The patient's clinical status improved thereafter, enabling left ventricular assist device ex-plantation after 17 months. To our knowledge, this is the first report of the use of left ventricular assist device support to reverse chronic anthracycline-induced heart failure.


Assuntos
Antraciclinas/efeitos adversos , Antineoplásicos/efeitos adversos , Cardiomiopatia Dilatada/terapia , Insuficiência Cardíaca/terapia , Coração Auxiliar , Adulto , Biópsia , Cardiomiopatia Dilatada/induzido quimicamente , Cardiomiopatia Dilatada/diagnóstico , Cardiomiopatia Dilatada/fisiopatologia , Doença Crônica , Remoção de Dispositivo , Feminino , Insuficiência Cardíaca/induzido quimicamente , Insuficiência Cardíaca/diagnóstico , Insuficiência Cardíaca/fisiopatologia , Ventrículos do Coração/efeitos dos fármacos , Ventrículos do Coração/fisiopatologia , Ventrículos do Coração/ultraestrutura , Doença de Hodgkin/tratamento farmacológico , Humanos , Microscopia Eletrônica , Desenho de Prótese , Indução de Remissão , Fatores de Tempo , Resultado do Tratamento , Função Ventricular Esquerda
5.
Nurs Res Pract ; 2012: 109251, 2012.
Artigo em Inglês | MEDLINE | ID: mdl-22567222

RESUMO

This study examined the prevalence of self-reported depressive symptoms and the self reported somatic depressive symptoms as measured by the Beck Depression Inventory-II (BDI-II) among patients hospitalized for acute coronary syndrome (ACS), and explored the impact of gender on both. A convenience sample of 789 adults (248 women and 541 men) was recruited for the study during hospital admission for ACS and participants were screened for self-reported depressive symptoms. BDI-II scores of ≥14 indicate a moderate level of depressive symptoms and this cut-off score was used to categorize patients into depressed and non-depressed groups. Pearson chi-square tests for independence (categorical variables) and t tests for independent samples (continuous variables) were used for gender comparisons. Results showed that depressive symptoms during ACS episodes were different between women and men. Women reported greater overall depressive symptoms (BDI-II mean = 11.89, S.D. = 9.68) than men (BDI-II mean = 9.00, S.D. = 7.93) (P < 0.000). Significantly more women (7.66%) were identified positive for somatic depressive symptoms (sleep and appetite disturbances and fatigue) than men (2.22%) (P = 0.0003). Findings support that there are gender differences in depressive symptoms experienced by patients hospitalized for ACS. Somatic symptoms of depression may be important indicators of depression especially among female ACS patients.

6.
Curr Treat Options Cardiovasc Med ; 13(4): 343-53, 2011 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-21674171

RESUMO

OPINION STATEMENT: Cardiogenic shock (CS), a state of cardiac dysfunction that results in systemic hypoperfusion and end-organ dysfunction, is associated with high in-hospital mortality. Various forms of mechanical circulatory support have been used to treat CS. First employed in the 1960s, the intra-aortic balloon pump (IABP) has been a mainstay in the treatment of acute CS. However, the IABP is unable to provide adequate support in many patients, and newer technologies, including extracorporeal membrane oxygenation and percutaneous ventricular assist devices, appear to be more effective in reversing CS. These devices are also useful for supporting patients during complex percutaneous coronary intervention. Perhaps most importantly, they can be used as a bridge to decision or definitive therapy in CS patients who are potential candidates for surgical ventricular assist devices or cardiac transplantation.

7.
J Heart Lung Transplant ; 30(8): 849-53, 2011 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-21530318

RESUMO

BACKGROUND: In this study we investigated gastrointestinal (GI) bleeding and its relationship to arteriovenous malformations (AVMs) in patients with the continuous-flow HeartMate II (HMII) left ventricular assist device (LVAD). METHODS: The records of 172 patients who received HMII support between November 2003 and June 2010 were reviewed. Patients were considered to have GI bleeding if they had 1 or more of the following symptoms: guaiac-positive stool; hematemesis; melena; active bleeding at the time of endoscopy or colonoscopy; and blood within the stomach at endoscopy or colonoscopy. The symptom(s) had to be accompanied by a decrease of >1 g/dl in the patient's hemoglobin level. The location of the bleeding was identified as upper GI tract, lower GI tract or both according to esophagogastroduodenoscopy, colonoscopy, small-bowel enteroscopy or mesenteric angiography. Post-LVAD implantation anti-coagulation therapy consisted of warfarin, aspirin and dipyridamole. RESULTS: Thirty-two of the 172 patients (19%) had GI bleeding after 63 ± 62 (range 8 to 241) days of HMII support. Ten patients had GI bleeding from an AVM; these included 3 patients who had 2 bleeding episodes and 2 patients who had 5 episodes each. Sixteen patients had upper GI bleeding (10 hemorrhagic gastritis, 4 gastric AVM, 2 Mallory-Weiss syndrome), 15 had lower GI bleeding (6 diverticulosis, 6 jejunal AVM, 1 drive-line erosion of the colon, 1 sigmoid polyp, 1 ischemic colitis) and 1 had upper and lower GI bleeding (1 colocutaneous and gastrocutaneous fistula). All GI bleeding episodes were successfully managed medically. CONCLUSIONS: Arteriovenous malformations can cause GI bleeding in patients with continuous-flow LVADs. In all cases in this series, GI bleeding was successfully managed without the need for surgical intervention.


Assuntos
Malformações Arteriovenosas/complicações , Malformações Arteriovenosas/epidemiologia , Hemorragia Gastrointestinal/epidemiologia , Hemorragia Gastrointestinal/etiologia , Coração Auxiliar , Disfunção Ventricular Esquerda/terapia , Adolescente , Adulto , Idoso , Anticoagulantes/efeitos adversos , Anticoagulantes/uso terapêutico , Transfusão de Eritrócitos , Feminino , Hemorragia Gastrointestinal/terapia , Humanos , Masculino , Pessoa de Meia-Idade , Plasma , Prevalência , Estudos Retrospectivos , Tromboembolia/prevenção & controle , Resultado do Tratamento , Suspensão de Tratamento , Adulto Jovem
8.
Tex Heart Inst J ; 38(1): 66-7, 2011.
Artigo em Inglês | MEDLINE | ID: mdl-21423473

RESUMO

A 45-year-old man underwent repair of a congenital bicuspid aortic valve and complex aortic-root aneurysm with an aortic-root xenograft. A CentriMag® left ventricular assist device was implanted for cardiac support and was subsequently replaced with a HeartMate II® left ventricular assist device. A day later, the patient was returned to the operating room for control of bleeding, and thrombotic occlusion of the prosthetic aortic valve was detected. The patient underwent thrombus removal, oversewing of the prosthetic valve, and bypass of the left anterior descending coronary artery. This case emphasizes the hazard of bypassing a failed left ventricle with a cardiac assist device after aortic valve replacement, even with a bioprosthesis.


Assuntos
Aneurisma Aórtico/cirurgia , Valva Aórtica/cirurgia , Bioprótese , Implante de Prótese Vascular/instrumentação , Prótese Vascular , Oclusão de Enxerto Vascular/etiologia , Implante de Prótese de Valva Cardíaca/instrumentação , Próteses Valvulares Cardíacas , Coração Auxiliar/efeitos adversos , Trombose/etiologia , Valva Aórtica/anormalidades , Implante de Prótese Vascular/efeitos adversos , Ponte de Artéria Coronária , Oclusão de Enxerto Vascular/cirurgia , Implante de Prótese de Valva Cardíaca/efeitos adversos , Humanos , Masculino , Pessoa de Meia-Idade , Desenho de Prótese , Reoperação , Trombose/cirurgia , Transplante Heterólogo , Resultado do Tratamento
9.
J Heart Lung Transplant ; 30(5): 515-22, 2011 May.
Artigo em Inglês | MEDLINE | ID: mdl-21257321

RESUMO

BACKGROUND: The use of large, pulsatile left ventricular assist devices (LVADs) has been limited in women because of their small body size. METHODS: We compared the survival outcomes, quality of life, and adverse events in 465 patients (104 women, 361 men) with advanced systolic heart failure in their first 18 months of support with the HeartMate II (Thoratec Corp, Pleasanton, CA) continuous-flow LVAD for bridge to transplantation. RESULTS: During the first 18 months, there were no differences in survival between women and men while on LVAD support (73% ± 3% vs 73% ± 5%, p = 0.855) but fewer women (40%) underwent heart transplantation than did men (55%; p = 0.001). More women continued on support after 18 months (p = 0.007). Median duration of support was 238 days for women and 184 days for men (p = 0.003). Mortality was 20% for women and 19% for men (p = 0.89). Adverse events were similar, with the exception of hemorrhagic stroke, which occurred more frequently in women (0.10 vs 0.04 events/patient-year, p = 0.02), and device-related infections, which occurred less frequently in women (0.23 vs 0.44, p = 0.006). Functional capacity and quality of life at 6 months improved significantly in women and men. CONCLUSIONS: Continuous-flow left ventricular assistance as a bridge to transplantation is associated with similar survival rates in women and men. Differences observed in higher stroke rates and fewer infections among women require further study.


Assuntos
Insuficiência Cardíaca/terapia , Transplante de Coração , Coração Auxiliar , Caracteres Sexuais , Adulto , Feminino , Insuficiência Cardíaca/mortalidade , Humanos , Incidência , Masculino , Pessoa de Meia-Idade , Qualidade de Vida , Estudos Retrospectivos , Acidente Vascular Cerebral/epidemiologia , Taxa de Sobrevida , Resultado do Tratamento
11.
N Engl J Med ; 362(20): 1890-900, 2010 May 20.
Artigo em Inglês | MEDLINE | ID: mdl-20413602

RESUMO

BACKGROUND: Endomyocardial biopsy is the standard method of monitoring for rejection in recipients of a cardiac transplant. However, this procedure is uncomfortable, and there are risks associated with it. Gene-expression profiling of peripheral-blood specimens has been shown to correlate with the results of an endomyocardial biopsy. METHODS: We randomly assigned 602 patients who had undergone cardiac transplantation 6 months to 5 years previously to be monitored for rejection with the use of gene-expression profiling or with the use of routine endomyocardial biopsies, in addition to clinical and echocardiographic assessment of graft function. We performed a noninferiority comparison of the two approaches with respect to the composite primary outcome of rejection with hemodynamic compromise, graft dysfunction due to other causes, death, or retransplantation. RESULTS: During a median follow-up period of 19 months, patients who were monitored with gene-expression profiling and those who underwent routine biopsies had similar 2-year cumulative rates of the composite primary outcome (14.5% and 15.3%, respectively; hazard ratio with gene-expression profiling, 1.04; 95% confidence interval, 0.67 to 1.68). The 2-year rates of death from any cause were also similar in the two groups (6.3% and 5.5%, respectively; P=0.82). Patients who were monitored with the use of gene-expression profiling underwent fewer biopsies per person-year of follow-up than did patients who were monitored with the use of endomyocardial biopsies (0.5 vs. 3.0, P<0.001). CONCLUSIONS: Among selected patients who had received a cardiac transplant more than 6 months previously and who were at a low risk for rejection, a strategy of monitoring for rejection that involved gene-expression profiling, as compared with routine biopsies, was not associated with an increased risk of serious adverse outcomes and resulted in the performance of significantly fewer biopsies. (ClinicalTrials.gov number, NCT00351559.)


Assuntos
Biópsia , Perfilação da Expressão Gênica , Rejeição de Enxerto/diagnóstico , Transplante de Coração , Adolescente , Adulto , Idoso , Biópsia/efeitos adversos , Biópsia/estatística & dados numéricos , Intervalos de Confiança , Endocárdio/patologia , Feminino , Seguimentos , Rejeição de Enxerto/genética , Rejeição de Enxerto/mortalidade , Transplante de Coração/mortalidade , Humanos , Terapia de Imunossupressão/efeitos adversos , Estimativa de Kaplan-Meier , Masculino , Pessoa de Meia-Idade , Miocárdio/patologia , Reoperação , Taxa de Sobrevida , Adulto Jovem
12.
J Am Coll Cardiol ; 54(4): 312-21, 2009 Jul 21.
Artigo em Inglês | MEDLINE | ID: mdl-19608028

RESUMO

OBJECTIVES: This study sought to evaluate the use of a continuous-flow rotary left ventricular assist device (LVAD) as a bridge to heart transplantation. BACKGROUND: LVAD therapy is an established treatment modality for patients with advanced heart failure. Pulsatile LVADs have limitations in design precluding their use for extended support. Continuous-flow rotary LVADs represent an innovative design with potential for small size and greater reliability by simplification of the pumping mechanism. METHODS: In a prospective, multicenter study, 281 patients urgently listed (United Network of Organ Sharing status 1A or 1B) for heart transplantation underwent implantation of a continuous-flow LVAD. Survival and transplantation rates were assessed at 18 months. Patients were assessed for adverse events throughout the study and for quality of life, functional status, and organ function for 6 months. RESULTS: Of 281 patients, 222 (79%) underwent transplantation, LVAD removal for cardiac recovery, or had ongoing LVAD support at 18-month follow-up. Actuarial survival on support was 72% (95% confidence interval: 65% to 79%) at 18 months. At 6 months, there were significant improvements in functional status and 6-min walk test (from 0% to 83% of patients in New York Heart Association functional class I or II and from 13% to 89% of patients completing a 6-min walk test) and in quality of life (mean values improved 41% with Minnesota Living With Heart Failure and 75% with Kansas City Cardiomyopathy questionnaires). Major adverse events included bleeding, stroke, right heart failure, and percutaneous lead infection. Pump thrombosis occurred in 4 patients. CONCLUSIONS: A continuous-flow LVAD provides effective hemodynamic support for at least 18 months in patients awaiting transplantation, with improved functional status and quality of life. (Thoratec HeartMate II Left Ventricular Assist System [LVAS] for Bridge to Cardiac Transplantation; NCT00121472).


Assuntos
Insuficiência Cardíaca/terapia , Coração Auxiliar , Adulto , Feminino , Transplante de Coração , Humanos , Masculino , Pessoa de Meia-Idade , Qualidade de Vida , Resultado do Tratamento
13.
J Heart Lung Transplant ; 28(3): 294-6, 2009 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-19285624

RESUMO

Managing arrhythmias is challenging in patients who have undergone heterotopic heart transplantation because of the superimposed rhythms of the native and donor hearts. We present the case of a 43-year-old man with a previously placed biventricular pacemaker who underwent heterotopic heart transplantation and later developed acute rejection of the donor heart, which led to bradycardia and pause-dependent ventricular fibrillation. The patient remained clinically stable in the short term, likely because of partial recovery of myocardial function in the native heart. He later underwent placement of a pacing lead in the donor heart, allowing linking of the two hearts via a biventricular pacemaker.


Assuntos
Bradicardia/etiologia , Transplante de Coração/efeitos adversos , Transplante Heterotópico/efeitos adversos , Fibrilação Ventricular/etiologia , Adulto , Bradicardia/diagnóstico , Humanos , Masculino , Fibrilação Ventricular/diagnóstico
14.
Tex Heart Inst J ; 35(2): 166-73, 2008.
Artigo em Inglês | MEDLINE | ID: mdl-18612451

RESUMO

Congestive heart failure has long been one of the most serious medical conditions in the United States; in fact, in the United States alone, heart failure accounts for 6.5 million days of hospitalization each year. One important goal of heart-failure therapy is to inhibit the progression of congestive heart failure through pharmacologic and device-based therapies. Therefore, there have been efforts to develop device-based therapies aimed at improving cardiac reserve and optimizing pump function to meet metabolic requirements. The course of congestive heart failure is often worsened by other conditions, including new-onset arrhythmias, ischemia and infarction, valvulopathy, decompensation, end-organ damage, and therapeutic refractoriness, that have an impact on outcomes. The onset of such conditions is sometimes heralded by subtle pathophysiologic changes, and the timely identification of these changes may promote the use of preventive measures. Consequently, device-based methods could in the future have an important role in the timely identification of the subtle pathophysiologic changes associated with congestive heart failure.


Assuntos
Técnicas de Diagnóstico Cardiovascular/instrumentação , Insuficiência Cardíaca/complicações , Insuficiência Cardíaca/fisiopatologia , Desfibriladores Implantáveis , Insuficiência Cardíaca/diagnóstico , Humanos , Monitorização Fisiológica/instrumentação , Valor Preditivo dos Testes
15.
Transplantation ; 84(4): 480-3, 2007 Aug 27.
Artigo em Inglês | MEDLINE | ID: mdl-17713431

RESUMO

Cardiac allograft hypertrophy is associated with persistent expression of cardiac tumor necrosis factor (TNF)-alpha. We investigated whether TNFalpha antagonism would impact allograft hypertrophy. EFECT (EFfect of Etanercept on Cardiac Transplantation) was a randomized, controlled, double-blind trial evaluating the effect of etanercept versus placebo treatment immediately posttransplant. The primary end-point was change in left ventricular (LV) mass after 6 months. Secondary endpoints included degree of collagen deposition at 6 months and incidence of adverse events. Forty-nine patients were randomized to either etanercept or placebo. LV mass increased significantly in both arms at 6 months, with a smaller increase in the etanercept group (19% vs. 33%, P=ns). Myocardial collagen content increased in the placebo, but not the etanercept, group (+39.8%, P<0.08 vs. -7.0%, P=NS). Allograft hypertrophy develops posttransplant with a corresponding increase in extracellular matrix. Etanercept appeared to decrease LV hypertrophy by decreasing extracellular matrix deposition.


Assuntos
Transplante de Coração/efeitos adversos , Hipertrofia Ventricular Esquerda/etiologia , Hipertrofia Ventricular Esquerda/prevenção & controle , Imunoglobulina G/uso terapêutico , Imunossupressores/uso terapêutico , Receptores do Fator de Necrose Tumoral/uso terapêutico , Fator de Necrose Tumoral alfa/antagonistas & inibidores , Colágeno/metabolismo , Método Duplo-Cego , Etanercepte , Matriz Extracelular/metabolismo , Matriz Extracelular/patologia , Feminino , Transplante de Coração/imunologia , Transplante de Coração/patologia , Ventrículos do Coração/metabolismo , Ventrículos do Coração/patologia , Humanos , Hipertrofia Ventricular Esquerda/patologia , Imunoglobulina G/efeitos adversos , Imunossupressores/efeitos adversos , Masculino , Pessoa de Meia-Idade , Miocárdio/metabolismo , Miocárdio/patologia , Receptores do Fator de Necrose Tumoral/metabolismo , Transplante Homólogo , Fator de Necrose Tumoral alfa/metabolismo
16.
Am J Physiol Heart Circ Physiol ; 288(4): H1982-8, 2005 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-15563542

RESUMO

Phospholemman (FXYD1), a 72-amino acid transmembrane protein abundantly expressed in the heart and skeletal muscle, is a major substrate for phosphorylation in the cardiomyocyte sarcolemma. Biochemical, cellular, and electrophysiological studies have suggested a number of possible roles for this protein, including ion channel modulator, taurine-release channel, Na(+)/Ca(2+) exchanger modulator, and Na-K-ATPase-associated subunit. We have generated a phospholemman-deficient mouse. The adult null mice exhibited increased cardiac mass, larger cardiomyocytes, and ejection fractions that were 9% higher by magnetic resonance imaging compared with wild-type animals. Notably, this occurred in the absence of hypertension. Total Na-K-ATPase activity was 50% lower in the phospholemman-deficient hearts. Expression (per unit of membrane protein) of total Na-K-ATPase was only slightly diminished, but expression of the minor alpha(2)-isoform, which has been specifically implicated in the control of contractility, was reduced by 60%. The absence of phospholemman thus results in a complex response, including a surprisingly large reduction in intrinsic Na-K-ATPase activity, changes in Na-K-ATPase isoform expression, increase in ejection fraction, and increase in cardiac mass. We hypothesize that a primary effect of phospholemman is to modulate the Na-K-ATPase and that its reduced activity initiates compensatory responses.


Assuntos
Cardiomegalia/metabolismo , Cardiomegalia/fisiopatologia , Proteínas de Membrana/genética , Proteínas de Membrana/metabolismo , Fosfoproteínas/genética , Fosfoproteínas/metabolismo , ATPase Trocadora de Sódio-Potássio/metabolismo , Volume Sistólico/fisiologia , Animais , Pressão Sanguínea , Cardiomegalia/patologia , Linhagem Celular , Ativação Enzimática , Óperon Lac , Camundongos , Camundongos Endogâmicos , Camundongos Mutantes , Miocárdio/patologia , Fenótipo , Sarcolema/enzimologia , Células-Tronco/citologia
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