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Aim: Determination of the phenotype of adult human atrial and ventricular myocytes based on gene expression and morphology. Methods: Atrial and ventricular cardiomyocytes were obtained from patients undergoing cardiac surgery using a modified isolation procedure. Myocytes were isolated and cultured with or without serum. The relative cell attachment promoting efficiency of several reagents was evaluated and compared. Morphological changes during long-term culture were assessed with phase contrast microscopy, morphometric analysis and immunocytochemistry or RT-PCR of sarcomeric markers including α-actinin, myosin light chain-2 (MLC-2) and the adhesion molecule, cadherin. Results: The isolation method produced viable rod-shaped atrial (16.6±6.0%, mean±S.E.; n=5) and ventricular cells (22.4±8.0%, mean±S.E.; n=5) in addition to significant numbers of apoptotic and necrotic cells. Cell dedifferentiation was characterized by the loss of sarcomeric structure, condensation and extrusion of sarcomeric proteins. Cells cultured with low serum recovered and assumed a flattened, spread form with two distinct morphologies apparent. Type I cells were large, had extensive sarcolemmal spreading, with stress fibers and nascent myofibrils, whilst type II cells appeared smaller, with more mature myofibril organisation and focal adhesions. Conclusion: Characterization of the redifferentiation capabilities of cultured adult cardiac myocytes in culture, provides an important system for comparing cardiomyocytes differentiating from human stem cells and provides the basis for an in vitro transplantation model to study interaction and communication between primary adult and stem cell-derived cardiomyocytes. [Copyright &y& Elsevier]

Aims To determine the impact of paroxysmal atrial fibrillation on quality of life and to determine the predictors of quality of life, particularly the role of symptomatology and autonomic function.Methods and Results The study group comprised 73 patients with paroxysmal atrial fibrillation (mean age 54·1 years, 51 males). On average, patients had a 3-year history of one paroxysm per week lasting 2h. Quality of life was assessed using the SF-36 (Medical Outcomes Study Short-Form Health Survey) and compared with age-matched controls. Autonomic function was assessed using Holter monitoring with analysis of heart rate variability and autonomic function tests. Symptoms during paroxysms of atrial fibrillation were also scored. Multivariate analysis was performed to identify independent predictors of quality of life. Quality of life scores were markedly lower in patients than in controls in four of the eight subscales (P<0·001): physical role function, emotional role function, vitality and general health. Structural heart disease did not predict quality of life, whereas frequency of paroxysms was predictive only of physical role function. In contrast, autonomic variables (baroreflex-sensitivity, total power (heart rate variability), response to deep breathing, 30–15 ratio (standing up)) were predictive in all four respective subscales (P<0·05), depressed vagal function being predictive of low scores. Symptoms, particularly severe perspiration, were also predictive of low scores (P<0·05).Conclusions This study shows that paroxysmal atrial fibrillation causes significant impairment of quality of life. Further, symptomatology and autonomic function are important predictors of quality of life in this patient group. [ABSTRACT FROM PUBLISHER]