Quality of life support in advanced cancer-web and technological interventions: systematic review and narrative synthesis.

BACKGROUND: As treatments continue to progress, patients with advanced cancer are living longer. However, ongoing physical side-effects and psychosocial concerns can compromise quality of life (QoL). Patients and physicians increasingly look to the internet and other technologies to address diverse supportive needs encountered across this evolving cancer trajectory. OBJECTIVES: 1. To examine the features and delivery of web and technological interventions supporting patients with advanced cancer. 2. To explore their efficacy relating to QoL and psychosocial well-being. METHODS: Relevant studies were identified through electronic database searches (MEDLINE, PsychINFO, Embase, CINAHL, CENTRAL, Web of Science and ProQuest) and handsearching. Findings were collated and explored through narrative synthesis. RESULTS: Of 5274 identified records, 37 articles were included. Interventions were evaluated within studies targeting advanced cancer (13) or encompassing all stages (24). Five subtypes emerged: Interactive Health Communication Applications (n=12), virtual programmes of support (n=11), symptom monitoring tools (n=8), communication conduits (n=3) and information websites (n=3). Modes of delivery ranged from self-management to clinically integrated. Support largely targeted psychosocial well-being, alongside symptom management and healthy living. Most studies (78%) evidenced varying degrees of efficacy through QoL and psychosocial measures. Intervention complexity made it challenging to distinguish the most effective components. Incomplete reporting limited risk of bias assessment. CONCLUSION: While complex and varied in their content, features and delivery, most interventions led to improvements in QoL or psychosocial well-being across the cancer trajectory. Ongoing development and evaluation of such innovations should specifically target patients requiring longer-term support for later-stage cancer. PROSPERO REGISTRATION NUMBER: CRD42018089153.

An unusual etiology of obstructive shock in the emergency department.

Obstructive shock describes any disease process that causes physical obstruction to blood flow into or out of the heart which results in impaired systemic oxygen or nutrient delivery. Common etiologies include cardiac tamponade, tension pneumothorax, and pulmonary embolus. However, several other causes exist and should prompt consideration in the correct clinical circumstances. In this report, we describe a 72-year-old female patient with history of hepatic cysts presenting with respiratory distress, mottled extremities, and abnormal vital signs. Contrast enhanced computed tomography scans showed a massive hepatic cyst which was compressing her vena cava and heart, causing hemodynamic instability. The patient was admitted to the ICU and the hepatic cyst was drained percutaneously, but ultimately, she succumbed to her illness post-operatively. This report highlights the importance of keeping a broad differential when considering etiologies of undifferentiated shock as well as the need for additional research regarding management of rare causes of obstructive shock.

Separate Effect of Perioperative Recombinant Human Factor VIIa Administration and Packed Red Blood Cell Transfusions on Midterm Survival in Lung Transplantation Recipients.

OBJECTIVE: The purpose of this study was to determine the relationship between blood product transfusion, with or without recombinant human activated factor VIIa, and survival after lung transplantation. DESIGN: Retrospective analysis of a single center with follow-up out to 6 years post-transplantation. SETTING: Single-center academic lung transplantation program. PARTICIPANTS: The study comprised 265 adult patients who underwent single or bilateral sequential lung transplantation from March 2011 to June 2017. INTERVENTIONS: Overall survival using Kaplan-Meier curves was compared among the following 3 cohorts: those not transfused with blood products, those transfused with blood products, and those given blood products and recombinant human activated factor VIIa. Cox proportional hazards regression was used to estimate hazard ratios (HRs), confidence intervals (CIs), and p values. MEASUREMENTS AND MAIN RESULTS: Seventy-eight patients received no packed red blood cell transfusions, 149 received packed red blood cell transfusions, and 38 received both packed red blood cell transfusions and recombinant human activated factor VII. Packed red blood cell transfusion was associated with an increased risk of mortality that did not reach statistical significance (HR 2.168, CI 0.978-4.805; p = 0.057). Additional packed red blood cells beyond 15 U were associated with worsened survival (HR 1.363, CI 1.137-1.633; p = 0.001), but recombinant human activated factor VIIa did not increase the risk of mortality. CONCLUSION: Blood product transfusion during and after lung transplantation is associated with decreased survival, especially with large-volume transfusions. Survival is not worse with recombinant human activated factor VIIa administration, but additional studies are needed to determine whether recombinant human activated factor VIIa administration reduces the need for blood product transfusions.

Assessment of Food Safety Knowledge and Behaviors of Cancer Patients Receiving Treatment.

Cancer patients receiving treatment are at a higher risk for the acquisition of foodborne illness than the general population. Despite this, few studies have assessed the food safety behaviors, attitudes, risk perceptions, and food acquisition behaviors of this population. Further, no studies have, yet, quantified the food safety knowledge of these patients. This study aims to fill these gaps in the literature by administering a thorough questionnaire to cancer patients seeking treatment in three hospitals in a Midwest, metropolitan area. Demographic, treatment, food security, and food safety knowledge, behaviors, attitudes, risk perceptions, and acquisition information was assessed for 288 patients. Specific unsafe attitudes, behaviors, and acquisition practices were identified. Most notable is that 49.4% (n = 139) of participants were not aware that they were at increased risk of foodborne infection, due to their disease and treatment. Additionally, though patients exhibited a general understanding of food safety, the participant average for correctly answering the food safety questions was 74.77% ± 12.24%. The section concerning food storage showed lowest participant knowledge, with an average score of 69.53% ± 17.47%. Finally, patients reporting low food security also reported a higher incidence of unsafe food acquisition practices (P < 0.05). These findings will help healthcare providers to better educate patients in the food safety practices necessary to decrease risk of foodborne infection, and to provide targeted food safety education to low-food-security patients.

An Evaluation of Factors Predicting Diet Quality among Cancer Patients.

A high diet quality is associated with a lower risk of cancer mortality. However, the predictive factors of diet quality among cancer patients are not well understood. This study determines the socio-demographic and disease-related factors that affect diet quality among cancer patients. Two hundred and forty-two cancer patients completed questionnaires assessing sociodemographic and disease-related characteristics. Diet quality was measured using the Healthy Eating Index 2010 (HEI). Independent sample t-tests and one-way ANOVA with post-hoc analysis using the Tukey HSD test were used to compare mean HEI scores across these characteristics. A regression model was used to determine factors that predicted diet quality. The overall HEI score among cancer patients was 61.59 (SD = 11.67). Patients with a high school degree or General Education Diploma (GED) or less had lower HEI scores (ß = -4.03, p = 0.04; ß = -7.77, p = 0.001, respectively) compared to those with college degrees. Additionally, homemakers had significantly higher HEI scores (ß = 7.95, p = 0.008) compared to those who worked at least 40 hours per week. Also, individuals with some types of cancers (e.g., endometrial or uterine) had significantly higher HEI scores (ß = 12.56, p = 0.002) than those with other cancers (e.g., head and neck). Our findings will help oncology healthcare providers identify and target cancer patients with specific demographic characteristics who are at increased risk for consuming poor-quality diets with much needed food resource interventions.

Death from Transfusion-Transmitted Anaplasmosis, New York, USA, 2017.

We report a death from transfusion-transmitted anaplasmosis in a 78-year-old man. The patient died of septic shock 2 weeks after a perioperative transfusion with erythrocytes harboring Anaplasma phagocytophilum. The patient's blood specimens were positive for A. phagocytophilum DNA beginning 7 days after transfusion; serologic testing remained negative until death.

Acute Cerebellar Ataxia: An Unusual Pediatric Case.

BACKGROUND: Acute cerebellar ataxia is a clinical syndrome with sudden onset of uncoordinated gait and normal mental status in young children. Although it has a benign clinical course, it often requires an exhaustive diagnostic work-up in order to rule out potentially life-threatening etiologies that present similarly. The wide differential encompasses causes from infections, brain masses, drugs, toxins, trauma, paraneoplastic syndromes, as well as hereditary or congenital disorders. CASE REPORT: We report on a 4-year-old boy with recent hand-foot-mouth disease who presented with acute cerebellar ataxia. In addition to his marked truncal ataxia and wide-based, staggering gait, he had slowness of speech, which is not commonly reported with this condition in the literature. WHY SHOULD AN EMERGENCY PHYSICIAN BE AWARE OF THIS?: Emergency physicians have a unique role in being first to evaluate pediatric ataxia and can make a significant impact on identifying potentially fatal mimickers of acute cerebellar ataxia. This article will attempt to outline major diagnostic considerations in order to aid emergency physicians through their clinical approach.

A phase I trial of high-dose clofarabine, etoposide, and cyclophosphamide and autologous peripheral blood stem cell transplantation in patients with primary refractory and relapsed and refractory non-Hodgkin lymphoma.

Clofarabine has significant single-agent activity in patients with indolent and aggressive non-Hodgkin lymphoma and synergizes with DNA-damaging drugs. Treatment, however, may be associated with severe and prolonged myelosuppression. We conducted a phase I trial to determine the maximum tolerated dose (MTD) of clofarabine in combination with high-dose etoposide and cyclophosphamide followed by autologous peripheral blood stem cell transplantation in patients with refractory non-Hodgkin lymphoma (NHL). Patients received clofarabine at 30-70 mg/m(2)/day on days -6 to -2 in successive cohorts, in combination with etoposide 60 mg/kg (day -8), and cyclophosphamide 100 mg/kg (day -6), followed by filgrastim-mobilized PBSC on day 0. Sixteen patients of median age 57 (range: 32-67) years with diffuse large B cell (n = 8), follicular (n = 5), or mantle cell (n = 3) lymphoma that was either primary refractory (n = 2) or relapsed and refractory (n = 14) were treated at 5 clofarabine dose levels: 30 (n = 3), 40 (n = 3), 50 (n = 3), 60 (n = 3), and 70 mg/m(2)/day (n = 4) in combination with etoposide and cyclophosphamide. All patients had grade 4 neutropenia and thrombocytopenia. Grade 3-4 nonhematologic toxicity was evenly distributed across all 5 dose levels, and included diarrhea (n = 3), mucositis (n = 1), nausea (n = 1), reversible elevation of alanine aminotranferease/aspartate aminotransferase (AST/ALT) (n = 1) or bilirubin (n = 1), and hemorrhagic cystitis (n = 1); all resolved by day +30 following transplantation. The MTD was not reached. No treatment-related deaths occurred. At day +30, 13 patients achieved a complete remission (CR) or unconfirmed CR (CR(U)), and 2 patients achieved a partial response, for an overall response rate of 94%. After a median follow-up of 691 days, the 1-year progression-free survival (PFS) and overall survival (OS) were 63% (95% confidence interval [CI]: 43%-91%) and 68% (95% CI: 49%-96%), respectively. We recommend clofarabine 70 mg/m(2)/day × 5 days as a phase II dose in combination with high-dose etoposide and cyclophosphamide for further testing as a preparative regimen in NHL patients undergoing autologous PBSC transplantation.

Importance of obtaining a detailed medical history in diagnosing emphysematous cystitis.

Pneumaturia has long been known to be the characteristic pathognomonic finding in emphysematous cystitis. However, its history is often difficult to elicit. Imaging studies are diagnostic in the majority of emphysematous cystitis cases described in the literature. The authors present a unique case in which the patient did not admit having pneumaturia until detailed questioning about her medical history was completed after diagnostic imaging. Had an earlier and more thorough medical history been conducted, the patient's diagnosis would have been achieved several months earlier, before presentation to the emergency department, as described in the present case. Early diagnosis is vital to decrease the morbidity and mortality associated with emphysematous cystitis.

Atrial cellular electrophysiological changes in patients with ventricular dysfunction may predispose to AF.

BACKGROUND: Left ventricular systolic dysfunction (LVSD) is a risk factor for atrial fibrillation (AF), but the atrial cellular electrophysiological mechanisms in humans are unclear. OBJECTIVE: This study sought to investigate whether LVSD in patients who are in sinus rhythm (SR) is associated with atrial cellular electrophysiological changes that could predispose to AF. METHODS: Right atrial myocytes were obtained from 214 consenting patients in SR who were undergoing cardiac surgery. Action potentials or ion currents were measured using the whole-cell-patch clamp technique. RESULTS: The presence of moderate or severe LVSD was associated with a shortened atrial cellular effective refractory period (ERP) (209 +/- 8 ms; 52 cells, 18 patients vs 233 +/- 7 ms; 134 cells, 49 patients; P <0.05); confirmed by multiple linear regression analysis. The left ventricular ejection fraction (LVEF) was markedly lower in patients with moderate or severe LVSD (36% +/- 4%, n = 15) than in those without LVSD (62% +/- 2%, n = 31; P <0.05). In cells from patients with LVEF 45%, by 24% and 18%, respectively. The LVEF and ERP were positively correlated (r = 0.65, P <0.05). The L-type calcium ion current, inward rectifier potassium ion current, and sustained outward ion current were unaffected by LVSD. The transient outward potassium ion current was decreased by 34%, with a positive shift in its activation voltage, and no change in its decay kinetics. CONCLUSION: LVSD in patients in SR is independently associated with a shortening of the atrial cellular ERP, which may be expected to contribute to a predisposition to AF.

Electrophysiological and arrhythmogenic effects of 5-hydroxytryptamine on human atrial cells are reduced in atrial fibrillation.

5-Hydroxytryptamine (5-HT) is proarrhythmic in atrial cells from patients in sinus rhythm (SR) via activation of 5-HT(4) receptors, but its effects in atrial cells from patients with atrial fibrillation (AF) are unknown. The whole-cell perforated patch-clamp technique was used to record L-type Ca(2+) current (I(CaL)), action potential duration (APD) and arrhythmic activity at 37 degrees C in enzymatically isolated atrial cells obtained from patients undergoing cardiac surgery, in SR or with chronic AF. In the AF group, 5-HT (10microM) produced an increase in I(CaL) of 115+/-21% above control (n=10 cells, 6 patients) that was significantly smaller than that in the SR group (232+/-33%; p<0.05; n=27 cells, 12 patients). Subsequent co-application of isoproterenol (1microM) caused a further increase in I(CaL) in the AF group (by 256+/-94%) that was greater than that in the SR group (22+/-6%; p<0.05). The APD at 50% repolarisation (APD(50)) was prolonged by 14+/-3ms by 5-HT in the AF group (n=37 cells, 14 patients). This was less than that in the SR group (27+/-4ms; p<0.05; n=58 cells, 24 patients). Arrhythmic activity in response to 5-HT was observed in 22% of cells in the SR group, but none was observed in the AF group (p<0.05). Atrial fibrillation was associated with reduced effects of 5-HT, but not of isoproterenol, on I(CaL) in human atrial cells. This reduced effect on I(CaL) was associated with a reduced APD(50) and arrhythmic activity with 5-HT. Thus, the potentially arrhythmogenic influence of 5-HT may be suppressed in AF-remodelled human atrium.

Post-operative atrial fibrillation is influenced by beta-blocker therapy but not by pre-operative atrial cellular electrophysiology.

INTRODUCTION: We investigated whether post-cardiac surgery (CS) new-onset atrial fibrillation (AF) is predicted by pre-CS atrial cellular electrophysiology, and whether the antiarrhythmic effect of beta-blocker therapy may involve pre-CS pharmacological remodeling. METHODS AND RESULTS: Atrial myocytes were obtained from consenting patients in sinus rhythm, just prior to CS. Action potentials and ion currents were recorded using whole-cell patch-clamp technique. Post-CS AF occurred in 53 of 212 patients (25%). Those with post-CS AF were older than those without (67 +/- 2 vs 62 +/- 1 years, P = 0.005). In cells from patients with post-CS AF, the action potential duration at 50% and 90% repolarization, maximum upstroke velocity, and effective refractory period (ERP) were 13 +/- 4 ms, 217 +/- 16 ms, 185 +/- 10 V/s, and 216 +/- 14 ms, respectively (n = 30 cells, 11 patients). Peak L-type Ca(2+) current, transient outward and inward rectifier K(+) currents, and the sustained outward current were -5.0 +/- 0.5, 12.9 +/- 2.4, -4.1 +/- 0.4, and 9.7 +/- 1.0 pA/pF, respectively (13-62 cells, 7-19 patients). None of these values were significantly different in cells from patients without post-CS AF (P > 0.05 for each, 60-279 cells, 29-86 patients), confirmed by multiple and logistic regression. In patients treated >7 days with a beta-blocker pre-CS, the incidence of post-CS AF was lower than in non-beta-blocked patients (13% vs 27%, P = 0.038). Pre-CS beta-blockade was associated with a prolonged pre-CS atrial cellular ERP (P = 0.001), by a similar degree (approximately 20%) in those with and without post-CS AF. CONCLUSION: Pre-CS human atrial cellular electrophysiology does not predict post-CS AF. Chronic beta-blocker therapy is associated with a reduced incidence of post-CS AF, unrelated to a pre-CS ERP-prolonging effect of this treatment.

Electrophysiological effects of prucalopride, a novel enterokinetic agent, on isolated atrial myocytes from patients treated with beta-adrenoceptor antagonists.

Prucalopride is a selective 5-hydroxytryptamine type 4 (5-HT4) receptor agonist developed for the treatment of gastrointestinal disorders. The endogenous agonist 5-HT acting via 5-HT4 receptors increases the L-type Ca2+ current (I(CaL)) with potentially proarrhythmic consequences (Pau et al., 2003). The aims of this study were to investigate the effects of prucalopride on I(CaL), action potentials, refractory period, and arrhythmic activity in human atrial myocytes, and to compare these with the effects of 5-HT, using the whole-cell perforated patch-clamp technique. Prucalopride (10(-9) to 10(-4) M) produced a concentration-dependent increase in I(CaL) amplitude, with a maximum response at 10 microM, from -5.3 +/- 0.6 to -10.9 +/- 1.5 pA/pF (p < 0.05; n = 22 cells, 10 patients), without affecting its voltage-dependence. Subsequent application of 10 microM 5-HT further increased I(CaL) to -17.7 +/- 2.8 pA/pF (p < 0.05; n = 16 cells, 9 patients). The increase in I(CaL) by prucalopride, 98 +/- 15%, was significantly smaller than that by 5-HT, 233 +/- 26% (p < 0.05). Prucalopride (10 microM) significantly increased the action potential duration at 50% repolarization (APD50) from 12 +/- 2 to 17 +/- 3 ms (p < 0.05; n = 22 cells, 9 patients). Following washout of prucalopride, 5-HT (10 microM) increased APD50, to a greater extent, from 14 +/- 3 to 32 +/- 7 ms (p < 0.05; n = 11 cells; 8 patients). The APD75, APD90, and effective refractory period were unaffected by prucalopride or 5-HT. Furthermore, 5-HT induced abnormal depolarizations in 27% of the cells studied, whereas prucalopride induced none (p < 0.05). In conclusion, in human atrial cells, prucalopride, at concentrations markedly above those used therapeutically, acted as partial agonist on I(CaL) and APD50, with no effect on late repolarization or refractory period, and was devoid of arrhythmic activity.

Electrophysiological effects of 5-hydroxytryptamine on isolated human atrial myocytes, and the influence of chronic beta-adrenoceptor blockade.

5-Hydroxytryptamine (5-HT) has been postulated to play a proarrhythmic role in the human atria via stimulation of 5-HT4 receptors. The aims of this study were to examine the effects of 5-HT on the L-type Ca2+ current (ICaL) action potential duration (APD), the effective refractory period (ERP) and arrhythmic activity in human atrial cells, and to assess the effects of prior treatment with beta-adrenoceptor antagonists. Isolated myocytes, from the right atrial appendage of 27 consenting patients undergoing cardiac surgery who were in sinus rhythm, were studied using the whole-cell perforated patch-clamp technique at 37 degrees C. 5-HT (1 nm-10 microm) caused a concentration-dependent increase in ICaL, which was potentiated in cells from beta-blocked (maximum response to 5-HT, Emax=299+/-12% increase above control) compared to non-beta-blocked patients (Emax=220+/-6%, P<0.05), but with no change in either the potency (log EC50: -7.09+/-0.07 vs -7.26+/-0.06) or Hill coefficient (nH: 1.5+/-0.6 vs 1.5+/-0.3) of the 5-HT concentration-response curve. 5-HT (10 microm) produced a greater increase in the APD at 50% repolarisation (APD50) in cells from beta-blocked patients (of 37+/-10 ms, i.e. 589+/-197%) vs non-beta-blocked patients (of 10+/-4 ms, i.e. 157+/-54%; P<0.05). Both the APD90 and the ERP were unaffected by 5-HT. Arrhythmic activity was observed in response to 5-HT in five of 17 cells (29%) studied from beta-blocked, compared to zero of 16 cells from the non-beta-blocked patients (P<0.05). In summary, the 5-HT-induced increase in calcium current was associated with a prolonged early plateau phase of repolarisation, but not late repolarisation or refractoriness, and the enhancement of these effects by chronic beta-adrenoceptor blockade was associated with arrhythmic potential.

Characterisation of the Na, K pump current in atrial cells from patients with and without chronic atrial fibrillation.

OBJECTIVE: To assess the contribution of the Na, K pump current (I(p)) to the action potential duration (APD) and effective refractory period (ERP) in human atrial cells, and to investigate whether I(p) contributes to the changes in APD and ERP associated with chronic atrial fibrillation (AF). METHODS: Action potentials and ion currents were recorded by whole-cell patch clamp in atrial myocytes isolated from consenting patients undergoing cardiac surgery, who were in sinus rhythm (SR) or AF (>3 months). RESULTS: In cells from patients in SR, the I(p) blocker, ouabain (10 microM) significantly depolarised the membrane potential, V(m), from -80+/-2 (mean+/-S.E.) to -73+/-2 mV, and lengthened both the APD (174+/-17 vs. 197+/-23 ms at 90% repolarisation) and ERP (198+/-22 vs. 266+/-14 ms; P<0.05 for each, Student's t-test, n=7 cells, 5 patients). With an elevated pipette [Na(+)] of 30 mM, I(p) was measured by increasing extracellular [K(+)] ([K(+)](o)) from 0 to 5.4 mM. This produced an outward shift in holding current at -40 mV, abolished by 10 microM ouabain. K(+)- and ouabain-sensitive current densities were similar, at 0.99+/-0.13 and 1.12+/-0.11 pA/pF, respectively (P>0.05; n=9 cells), confirming the K(+)-induced current as I(p). I(p) increased linearly with increasing V(m) between -120 and +60 mV (n=25 cells). Stepwise increments in [K(+)](o) (between 0 and 10 mM) increased I(p) in a concentration-dependent manner (maximum response, E(max)=1.19+/-0.09 pA/pF; EC(50)=1.71+/-0.15 mM; n=27 cells, 9 patients). In cells from patients in AF, the sensitivity of I(p) to both V(m) and [K(+)](o) (E(max)=1.02+/-0.05 pA/pF, EC(50)=1.54+/-0.11 mM; n=44 cells, 9 patients) was not significantly different from that in cells from patients in SR. Within the group of patients in AF, long-term digoxin therapy (n=5 patients) was associated with a small, but significant, reduction in E(max) (0.92+/-0.07 pA/pF) and EC(50) (1.35+/-0.15 mM) compared with non-treatment (E(max)=1.13+/-0.08 pA/pF, EC(50)=1.76+/-0.14 mM; P<0.05 for each, n=4 patients). In cells from non-digoxin-treated patients in AF, the voltage- and [K(+)](o)-sensitivity (E(max) and EC(50)) were similar to those in cells from patients in SR. CONCLUSIONS: The Na, K pump current contributes to the human atrial cell V(m), action potential shape and ERP. However, the similarity in I(p) sensitivity to both [K(+)](o) and V(m) between atrial cells from patients with and without chronic AF indicates that I(p) is not involved in AF-induced electrophysiological remodelling in patients.

Chronic beta-adrenoceptor blockade and human atrial cell electrophysiology: evidence of pharmacological remodelling.

OBJECTIVE: Chronic beta-adrenoceptor antagonist (beta-blocker) treatment reduces the incidence of reversion to AF in patients, possibly via an adaptive myocardial response. However, the underlying electrophysiological mechanisms are presently unclear. We aimed to investigate electrophysiological changes in human atrial cells associated with chronic treatment with beta-blockers and other cardiovascular-acting drugs. METHODS: Myocytes were isolated enzymatically from the right atrial appendage of 40 consenting patients who were in sinus rhythm. The cellular action potential duration (APD), effective refractory period (ERP), L-type Ca(2+) current (I(CaL)), transient (I(TO)) and sustained (I(KSUS)) outward K(+) currents, and input resistance (R(i)) were recorded using the whole cell patch clamp. Drug treatments and clinical characteristics were compared with electrophysiological measurements using simple and multiple regression analyses. P<0.05 was taken as statistically significant. RESULTS: In atrial cells from patients treated chronically with beta-blockers, the APD(90) and ERP (75 beats/min stimulation) were significantly longer, at 213+/-11 and 233+/-11 ms, respectively (n=15 patients), than in cells from non-beta-blocked patients, at 176+/-12 and 184+/-12 ms (n=11). These cells also displayed a significantly reduced action potential phase 1 velocity (22+/-3 vs. 34+/-3 V/s). Chronic beta-blockade was also associated with a significant reduction in the heart rate (58+/-3 vs. 69+/-5 beats/min) and in the density of I(TO) (8.7+/-1.3 vs. 13.7+/-2.1 pA/pF), an increase in the R(i) (214+/-24 vs. 132+/-14 MOmega), but no significant change in I(CaL) or I(KSUS). The I(TO) blocker 4-aminopyridine largely mimicked the changes in phase 1 and ERP associated with chronic beta-blockade, in cells from non-beta-blocked patients. Chronic treatment of patients with calcium channel blockers or angiotensin converting enzyme inhibitors (n=11-13 patients) was not associated with any significant changes in atrial cell electrophysiology. CONCLUSION: The observed atrial cellular electrophysiological changes associated with chronic beta-blockade are consistent with a long-term adaptive response, a type of 'pharmacological remodelling', and provide mechanistic evidence supportive of the anti-arrhythmic actions of beta-blockade.