Sympathetic neural overdrive and diminished exercise capacity in reduced ejection fraction heart failure related to anthracycline-based chemotherapy.

Cardiotoxicity is the most worrying cardiovascular alteration in patients treated with chemotherapy. To improve the understanding regarding the cardiotoxicity, we studied whether 1) patients with cardiac dysfunction related to anthracycline-based chemotherapy have augmented sympathetic nerve activity and decreased exercise capacity and 2) these responses are similar to those observed in patients with heart failure caused by other etiologies. Sixteen patients with heart failure with reduced ejection fraction related to anthracycline-based chemotherapy with or without chest radiation (HFrEFCA), 10 patients with heart failure with reduced ejection not related to cancer therapy (HFrEF), and 16 age- and body mass index (BMI)-matched healthy control subjects were studied. Left ventricular ejection fraction (LVEF, echocardiography), peak oxygen consumption (peak V̇o2, cardiopulmonary exercise test), muscle sympathetic nerve activity (MSNA, microneurography), and forearm blood flow (FBF, venous occlusion plethysmography) were measured. We found that peak oxygen consumption peak V̇o2 and LVEF were significantly reduced in patients with HFrEFCA compared with that of control subjects (P < 0.0001) but similar to those found in patients with HFrEFCA. The sympathetic nerve activity burst frequency and incidence were significantly higher in patients with HFrEFCA than that in control subjects (P < 0.0001). No differences were found between patients with HFrEF and HFrEFCA. Peak V̇o2 was inversely associated with MSNA burst frequency (r = -0.53, P = 0.002) and burst incidence (r = -0.38, P = 0.01) and directly associated with LVEF (r = 0.71, P < 0.0001). Taken together, we conclude that patients who develop heart failure due to anthracycline-based chemotherapy have sympathetic neural overdrive and reduced exercise capacity. In addition, these physiological changes are similar to those observed in patients with HFrEF.NEW & NOTEWORTHY Patients with heart failure with reduced ejection fraction related to anthracycline-based chemotherapy have increased sympathetic nerve activity and decreased exercise capacity. These alterations in autonomic control and physical capacity are similar to those observed in patients with heart failure due to other etiologies. These findings highlight the importance of special care of oncological patients treated with chemotherapy.

Neurovascular and hemodynamic responses to mental stress and exercise in severe COVID-19 survivors.

Previous studies show that COVID-19 survivors have elevated muscle sympathetic nerve activity (MSNA), endothelial dysfunction, and aortic stiffening. However, the neurovascular responses to mental stress and exercise are still unexplored. We hypothesized that COVID-19 survivors, compared with age- and body mass index (BMI)-matched control subjects, exhibit abnormal neurovascular responses to mental stress and physical exercise. Fifteen severe COVID-19 survivors (aged: 49 ± 2 yr, BMI: 30 ± 1 kg/m2) and 15 well-matched control subjects (aged: 46 ± 3 yr, BMI: 29 ± 1 kg/m2) were studied. MSNA (microneurography), forearm blood flow (FBF), and forearm vascular conductance (FVC, venous occlusion plethysmography), mean arterial pressure (MAP, Finometer), and heart rate (HR, ECG) were measured during a 3-min mental stress (Stroop Color-Word Test) and during a 3-min isometric handgrip exercise (30% of maximal voluntary contraction). During mental stress, MSNA (frequency and incidence) responses were higher in COVID-19 survivors than in controls (P < 0.001), and FBF and FVC responses were attenuated (P < 0.05). MAP was similar between the groups (P > 0.05). In contrast, the MSNA (frequency and incidence) and FBF and FVC responses to handgrip exercise were similar between the groups (P > 0.05). MAP was lower in COVID-19 survivors (P < 0.05). COVID-19 survivors exhibit an exaggerated MSNA and blunted vasodilatory response to mental challenge compared with healthy adults. However, the neurovascular response to handgrip exercise is preserved in COVID-19 survivors. Overall, the abnormal neurovascular control in response to mental stress suggests that COVID-19 survivors may have an increased risk to cardiovascular events during mental challenge.

High risk coronavirus disease 2019: The primary results of the CoronaHeart multi-center cohort study

BACKGROUND: Patients with Coronavirus Disease 2019 (COVID-19) may present high risk features during hospitalization, including cardiovascular manifestations. However, less is known about the factors that may further increase the risk of death in these patients. METHODS: We included patients with COVID-19 and high risk features according to clinical and/or laboratory criteria at 21 sites in Brazil from June 10th to October 23rd of 2020. All variables were collected until hospital discharge or in-hospital death. RESULTS: A total of 2546 participants were included (mean age 65 years; 60.3% male). Overall, 70.8% were admitted to intensive care units and 54.2% had elevated troponin levels. In-hospital mortality was 41.7%. An interaction among sex, age and mortality was found (p = 0.007). Younger women presented higher rates of death than men (30.0% vs 22.9%), while older men presented higher rates of death than women (57.6% vs 49.2%). The strongest factors associated with in-hospital mortality were need for mechanical ventilation (odds ratio [OR] 8.2, 95% confidence interval [CI] 5.4­12.7), elevated C-reactive protein (OR 2.3, 95% CI 1.7­2.9), cancer (OR 1.8, 95 %CI 1.2­2.9), and elevated troponin levels (OR 1.8, 95% CI 1.4­2.3). A risk score was developed for risk assessment of in-hospital mortality. CONCLUSIONS: This cohort showed that patients with COVID-19 and high risk features have an elevated rate of in-hospital mortality with differences according to age and sex. These results highlight unique aspects of this population and might help identifying patients who may benefit from more careful initial surveillance and potential subsequent interventional therapies

High risk coronavirus disease 2019: The primary results of the CoronaHeart multi-center cohort study.

BACKGROUND: Patients with Coronavirus Disease 2019 (COVID-19) may present high risk features during hospitalization, including cardiovascular manifestations. However, less is known about the factors that may further increase the risk of death in these patients. METHODS: We included patients with COVID-19 and high risk features according to clinical and/or laboratory criteria at 21 sites in Brazil from June 10th to October 23rd of 2020. All variables were collected until hospital discharge or in-hospital death. RESULTS: A total of 2546 participants were included (mean age 65 years; 60.3% male). Overall, 70.8% were admitted to intensive care units and 54.2% had elevated troponin levels. In-hospital mortality was 41.7%. An interaction among sex, age and mortality was found (p = 0.007). Younger women presented higher rates of death than men (30.0% vs 22.9%), while older men presented higher rates of death than women (57.6% vs 49.2%). The strongest factors associated with in-hospital mortality were need for mechanical ventilation (odds ratio [OR] 8.2, 95% confidence interval [CI] 5.4-12.7), elevated C-reactive protein (OR 2.3, 95% CI 1.7-2.9), cancer (OR 1.8, 95 %CI 1.2-2.9), and elevated troponin levels (OR 1.8, 95% CI 1.4-2.3). A risk score was developed for risk assessment of in-hospital mortality. CONCLUSIONS: This cohort showed that patients with COVID-19 and high risk features have an elevated rate of in-hospital mortality with differences according to age and sex. These results highlight unique aspects of this population and might help identifying patients who may benefit from more careful initial surveillance and potential subsequent interventional therapies.

Patients with COVID-19 who experience a myocardial infarction have complex coronary morphology and high in-hospital mortality: Primary results of a nationwide angiographic study.

OBJECTIVES: We aimed to explore angiographic patterns and in-hospital outcomes of patients with concomitant coronavirus disease-19 (COVID-19) and myocardial infarction (MI). BACKGROUND: Patients with COVID-19 may experience MI during the course of the viral infection. However, this association is currently poorly understood. METHODS: This is a multicenter prospective study of consecutive patients with concomitant COVID-19 and MI who underwent coronary angiography. Quantitative and qualitative coronary angiography were analyzed by two observers in an independent core lab. RESULTS: A total of 152 patients were included, of whom 142 (93.4%) had COVID-19 diagnosis confirmation. The median time between symptom onset and hospital admission was 5 (1-10) days. A total of 83 (54.6%) patients presented with ST-elevation MI. The median angiographic Syntax score was 16 (9.0-25.3) and 69.0% had multi-vessel disease. At least one complex lesion was found in 73.0% of patients, 51.3% had a thrombus containing lesion, and 57.9% had myocardial blush grades 0/1. The overall in-hospital mortality was 23.7%. ST-segment elevation MI presentation and baseline myocardial blush grades 0 or 1 were independently associated with a higher risk of death (HR 2.75, 95%CI 1.30-5.80 and HR 3.73, 95%CI 1.61-8.61, respectively). CONCLUSIONS: Patients who have a MI in the context of ongoing COVID-19 mostly present complex coronary morphologies, implying a background of prior atherosclerotic disease superimposed on a thrombotic milieu. The in-hospital prognosis is poor with a markedly high mortality, prompting further investigation to better clarify this newly described condition.

Patients with COVID-19 who experience a myocardial infarction have complex coronary morphology and high in-hospital mortality: Primary results of a nationwide angiographic study

OBJECTIVES: We aimed to explore angiographic patterns and in-hospital outcomes of patients with concomitant coronavirus disease-19 (COVID-19) and myocardial infarction (MI). BACKGROUND: Patients with COVID-19 may experience MI during the course of the viral infection. However, this association is currently poorly understood. METHODS: This is a multicenter prospective study of consecutive patients with concomitant COVID-19 and MI who underwent coronary angiography. Quantitative and qualitative coronary angiography were analyzed by two observers in an independent core lab. RESULTS: A total of 152 patients were included, of whom 142 (93.4%) had COVID-19 diagnosis confirmation. The median time between symptom onset and hospital admission was 5 (1­10) days. A total of 83 (54.6%) patients presented with ST elevation MI. The median angiographic Syntax score was 16 (9.0­25.3) and 69.0% had multi-vessel disease. At least one complex lesion was found in 73.0% of patients, 51.3% had a thrombus containing lesion, and 57.9% had myocardial blush grades 0/1. The overall in-hospital mortality was 23.7%. ST-segment elevation MI presentation and baseline myocardial blush grades 0 or 1 were independently associated with a higher risk of death (HR 2.75, 95%CI 1.30­5.80 and HR 3.73, 95%CI 1.61­8.61, respectively). CONCLUSIONS: Patients who have a MI in the context of ongoing COVID-19 mostly present complex coronary morphologies, implying a background of prior atherosclerotic disease superimposed on a thrombotic milieu. The in-hospital prognosis is poor with a markedly high mortality, prompting further investigation to better clarify this newly described condition.

Exercise Rehabilitation Improves Cardiac Volumes and Functional Capacity in Patients With Endomyocardial Fibrosis: A RANDOMIZED CONTROLLED TRIAL.

PURPOSE: Endomyocardial fibrosis (EMF) is a restrictive cardiomyopathy associated with low functional capacity and high mortality rates. Exercise training has been proved to be a nonpharmacological treatment of cardiovascular diseases. Therefore, the purpose of this study was to determine the effects of exercise rehabilitation in EMF patients. METHODS: Twenty-two EMF patients, functional classes II and III (New York Heart Association [NYHA]), were randomized to the control (C-EMF) or exercise rehabilitation (Rehab-EMF) group. Patients in the Rehab-EMF group underwent 4 mo of exercise rehabilitation, whereas patients in the C-EMF group were instructed to maintain their usual daily routine. Peak oxygen uptake ((Equation is included in full-text article.)O2), cardiac function, and quality of life were evaluated. All assessments were performed at baseline and after 4 mo. RESULTS: After 4 mo of rehabilitation, peak (Equation is included in full-text article.)O2 increased in the Rehab-EMF group (17.4 ± 3.0 to 19.7 ± 4.4 mL/kg/min, P < .001), whereas the C-EMF group showed no difference (15.3 ± 3.0 to 15.0 ± 2.0 mL/kg/min, P = .87). Also, post-intervention, peak (Equation is included in full-text article.)O2 in the Rehab-EMF group was greater than that in the C-EMF group (P < .001). Furthermore, the Rehab-EMF group, when compared to the C-EMF group, showed an increase in left ventricular end-diastolic volume (102.1 ± 64.6 to 136.2 ± 75.8 mL vs 114.4 ± 55.0 to 100.4 ± 49.9 mL, P < .001, respectively) and decrease in left atrial diastolic volume (69.0 ± 33.0 to 34.9 ± 15.0 mL vs 44.6 ± 21.0 to 45.6 ± 23.0 mL, P < .001, respectively). Quality-of-life scores also improved in the Rehab-EMF group, whereas the C-EMF group showed no change (45 ± 23 to 27 ± 15 vs 47 ± 15 to 45 ± 17, P < .001, respectively). CONCLUSION: Exercise rehabilitation is a nonpharmacological intervention that improves functional capacity, cardiac volumes, and quality of life in EMF patients after endocardial resection surgery. In addition, exercise rehabilitation should be prescribed to EMF patients to improve their clinical condition.

Resting spontaneous baroreflex sensitivity and cardiac autonomic control in anabolic androgenic steroid users.

OBJECTIVES: Misuse of anabolic androgenic steroids in athletes is a strategy used to enhance strength and skeletal muscle hypertrophy. However, its abuse leads to an imbalance in muscle sympathetic nerve activity, increased vascular resistance, and increased blood pressure. However, the mechanisms underlying these alterations are still unknown. Therefore, we tested whether anabolic androgenic steroids could impair resting baroreflex sensitivity and cardiac sympathovagal control. In addition, we evaluate pulse wave velocity to ascertain the arterial stiffness of large vessels. METHODS: Fourteen male anabolic androgenic steroid users and 12 nonusers were studied. Heart rate, blood pressure, and respiratory rate were recorded. Baroreflex sensitivity was estimated by the sequence method, and cardiac autonomic control by analysis of the R-R interval. Pulse wave velocity was measured using a noninvasive automatic device. RESULTS: Mean spontaneous baroreflex sensitivity, baroreflex sensitivity to activation of the baroreceptors, and baroreflex sensitivity to deactivation of the baroreceptors were significantly lower in users than in nonusers. In the spectral analysis of heart rate variability, high frequency activity was lower, while low frequency activity was higher in users than in nonusers. Moreover, the sympathovagal balance was higher in users. Users showed higher pulse wave velocity than nonusers showing arterial stiffness of large vessels. Single linear regression analysis showed significant correlations between mean blood pressure and baroreflex sensitivity and pulse wave velocity. CONCLUSIONS: Our results provide evidence for lower baroreflex sensitivity and sympathovagal imbalance in anabolic androgenic steroid users. Moreover, anabolic androgenic steroid users showed arterial stiffness. Together, these alterations might be the mechanisms triggering the increased blood pressure in this population.

Resting spontaneous baroreflex sensitivity and cardiac autonomic control in anabolic androgenic steroid users

OBJECTIVES: Misuse of anabolic androgenic steroids in athletes is a strategy used to enhance strength and skeletal muscle hypertrophy. However, its abuse leads to an imbalance in muscle sympathetic nerve activity, increased vascular resistance, and increased blood pressure. However, the mechanisms underlying these alterations are still unknown. Therefore, we tested whether anabolic androgenic steroids could impair resting baroreflex sensitivity and cardiac sympathovagal control. In addition, we evaluate pulse wave velocity to ascertain the arterial stiffness of large vessels. METHODS: Fourteen male anabolic androgenic steroid users and 12 nonusers were studied. Heart rate, blood pressure, and respiratory rate were recorded. Baroreflex sensitivity was estimated by the sequence method, and cardiac autonomic control by analysis of the R-R interval. Pulse wave velocity was measured using a noninvasive automatic device. RESULTS: Mean spontaneous baroreflex sensitivity, baroreflex sensitivity to activation of the baroreceptors, and baroreflex sensitivity to deactivation of the baroreceptors were significantly lower in users than in nonusers. In the spectral analysis of heart rate variability, high frequency activity was lower, while low frequency activity was higher in users than in nonusers. Moreover, the sympathovagal balance was higher in users. Users showed higher pulse wave velocity than nonusers showing arterial stiffness of large vessels. Single linear regression analysis showed significant correlations between mean blood pressure and baroreflex sensitivity and pulse wave velocity. CONCLUSIONS: Our results provide evidence for lower baroreflex sensitivity and sympathovagal imbalance in anabolic androgenic steroid users. Moreover, anabolic androgenic steroid users showed arterial stiffness. Together, these alterations might be the mechanisms triggering the increased blood pressure in this population.

Characterization of Cardiopulmonary Exercise Testing Variables in Patients with Endomyocardial Fibrosis after Endocardial Resection / Caracterização das Variáveis do Teste de Esforço Cardiopulmonar em Pacientes com Endomiocardiofibrose após Cirurgia de Ressecção Endocárdica

Abstract Background: Endomyocardial fibrosis (EMF) is a rare disease, characterized by diastolic dysfunction which leads to reduced peak oxygen consumption (VO2). Cardiopulmonary exercise testing (CPET) has been proved to be a fundamental tool to identify central and peripheral alterations. However, most studies prioritize peak VO2 as the main variable, leaving aside other important CPET variables that can specify the severity of the disease and guide the clinical treatment. Objective: The aim of this study was to evaluate central and peripheral limitations in symptomatic patients with EMF by different CPET variables. Methods: Twenty-six EMF patients (functional class III, NYHA) were compared with 15 healthy subjects (HS). Functional capacity was evaluated using CPET and diastolic and systolic functions were evaluated by echocardiography. Results: Age and gender were similar between EMF patients and HS. Left ventricular ejection fraction was normal in EMF patients, but decreased compared to HS. Peak heart rate, peak workload, peak VO2, peak oxygen (O2) pulse and peak pulmonary ventilation (VE) were decreased in EMF compared to HS. Also, EMF patients showed increased Δ heart rate /Δ oxygen uptake and Δ oxygen uptake /Δ work rate compared to HS. Conclusion: Determination of the aerobic capacity by noninvasive respiratory gas exchange during incremental exercise provides additional information about the exercise tolerance in patients with EMF. The analysis of different CPET variables is necessary to help us understand more about the central and peripheral alterations cause by both diastolic dysfunction and restrictive pattern.

Resumo Fundamento: A endomiocardiofibrose (EMF) é uma doença rara, caracterizada por disfunção diastólica que leva à redução consumo de oxigênio (VO2) pico. O teste de esforço cardiopulmonar (TECP) tem se mostrado uma ferramenta fundamental na identificação de alterações centrais e periféricas. No entanto, a maioria dos estudos prioriza o VO2 pico como a variável principal, em detrimento de outras importantes variáveis do TECP que poderiam identificar a gravidade da doença e direcionar o tratamento clínico. Objetivo: O objetivo deste estudo foi avaliar limitações centrais e periféricas em pacientes com EMF sintomáticos por meio de variáveis do TECP. Métodos: Vinte e seis pacientes com EMF (classe funcional III, NYHA) foram comparados com 15 indivíduos controle saudáveis (CS). A capacidade funcional foi avaliada por TECP e funções sistólicas e diastólicas por ecocardiografia. Resultados: A idade e o gênero foram similares entre pacientes com EMF e CS. A fração de ejeção do ventrículo esquerdo foi normal em pacientes com EMF, porém diminuída em comparação aos CS. Os picos de frequência cardíaca, carga de trabalho, VO2, pulso de oxigênio (O2) e da ventilação pulmonar (VE) estavam diminuídos em pacientes com EMF em comparação aos CS. Ainda, os pacientes com EMF apresentaram Δ frequência cardíaca /Δ consumo de oxigênio e Δ consumo de oxigênio /Δ taxa de trabalho aumentados em comparação aos CS. Conclusão: A determinação da capacidade aeróbica por troca respiratória não invasiva durante exercício progressivo fornece informações sobre a tolerância ao exercício em pacientes com EMF. É necessária uma análise das diferentes variáveis do TECP para nos ajudar a compreender mais acerca das alterações centrais e periféricas causadas tanto pela disfunção diastólica como pelo padrão restritivo.

Cardiac and peripheral autonomic control in restrictive cardiomyopathy.

AIMS: Autonomic dysfunction determines the advance of dilated cardiomyopathy (DCM) and is related to poor outcomes. However, this autonomic imbalance is unknown in patients with restrictive cardiomyopathy (RCM) even though they have similar symptoms and poor quality of life as DCM patients have. The aim of this study was to evaluate if autonomic and neurovascular controls were altered in RCM patients. METHODS AND RESULTS: Fifteen RCM patients, 10 DCM patients, and 10 healthy subjects were evaluated. Heart rate and blood pressure (BP) were recorded. Peripheral sympathetic activity [muscle sympathetic nerve activity (MSNA)] by microneurography and cardiac sympathetic activity by power spectrum analysis of heart rate variability. Spontaneous baroreflex sensitivity (BRS) was evaluated by the sequence method and forearm blood flow by venous occlusion plethysmography. Both cardiomyopathy groups had higher MSNA frequency (P < 0.001) and MSNA incidence (P < 0.001), higher cardiac sympathovagal balance (P < 0.02), reduced BRS for increase (P = 0.002) and for decrease in BP (P = 0.002), and lower forearm blood flow (P < 0.001) compared with healthy subjects. We found an inverse correlation between BRS for increase and decrease in BP and peripheral sympathetic activity (r = -0.609, P = 0.001 and r = -0.648, P < 0.001, respectively) and between BRS for increase and decrease in BP and cardiac sympathetic activity (r = -0.503, P = 0.03 and r = -0.487, P = 0.04, respectively). CONCLUSIONS: The RCM patients had cardiac and peripheral autonomic dysfunctions associated with peripheral vasoconstriction. Nonetheless, the presence of normal ejection fraction underestimates the evolution of the disease and makes clinical treatment difficult. These alterations could lead to a similar cardiovascular risk as that observed in DCM patients.

Characterization of Cardiopulmonary Exercise Testing Variables in Patients with Endomyocardial Fibrosis after Endocardial Resection.

BACKGROUND: Endomyocardial fibrosis (EMF) is a rare disease, characterized by diastolic dysfunction which leads to reduced peak oxygen consumption (VO2). Cardiopulmonary exercise testing (CPET) has been proved to be a fundamental tool to identify central and peripheral alterations. However, most studies prioritize peak VO2 as the main variable, leaving aside other important CPET variables that can specify the severity of the disease and guide the clinical treatment. OBJECTIVE: The aim of this study was to evaluate central and peripheral limitations in symptomatic patients with EMF by different CPET variables. METHODS: Twenty-six EMF patients (functional class III, NYHA) were compared with 15 healthy subjects (HS). Functional capacity was evaluated using CPET and diastolic and systolic functions were evaluated by echocardiography. RESULTS: Age and gender were similar between EMF patients and HS. Left ventricular ejection fraction was normal in EMF patients, but decreased compared to HS. Peak heart rate, peak workload, peak VO2, peak oxygen (O2) pulse and peak pulmonary ventilation (VE) were decreased in EMF compared to HS. Also, EMF patients showed increased Δ heart rate /Δ oxygen uptake and Δ oxygen uptake /Δ work rate compared to HS. CONCLUSION: Determination of the aerobic capacity by noninvasive respiratory gas exchange during incremental exercise provides additional information about the exercise tolerance in patients with EMF. The analysis of different CPET variables is necessary to help us understand more about the central and peripheral alterations cause by both diastolic dysfunction and restrictive pattern.

A simple and inexpensive method for laparoscopic appendectomy.

Laparoscopic appendectomy (LA) was introduced into clinical practice by Kurt Semm in 1983. Since then, a number of methods for performing LA have emerged in the literature. However, the majority of these modifications require costly equipment. In this short technical chapter, we describe a very simple and inexpensive method of performing this procedure without resorting to any additional expensive paraphernalia.

Deoxycholic acid at neutral and acid pH, is genotoxic to oesophageal cells through the induction of ROS: The potential role of anti-oxidants in Barrett's oesophagus.

Bile acids are often refluxed into the lower oesophagus and are candidate carcinogens in the development of oesophageal adenocarcinoma. We show here that the secondary bile acid, deoxycholic acid (DCA), is the only one of the commonly refluxed bile acids tested here, to show genotoxicity, in terms of chromosome damage and mutation induction in the human p53 gene. This genotoxicity was apparent at both neutral and acidic pH, whilst there was a considerable increase in bile-induced toxicity at acidic pH. The higher levels of cell death and low cell survival rates at acidic pH may imply that acid bile exposure is toxic rather than carcinogenic, as dead cells do not seed cancer development. We also show that DCA (at neutral and acid pH) induced the release of reactive oxygen species (ROS) within the cytoplasm of exposed cells. We further demonstrate that the genotoxicity of DCA is ROS mediated, as micronucleus induction was significantly reduced when cells were treated with DCA + the anti-oxidant vitamin C. In conclusion, we show that DCA, is an effective genotoxin at both neutral and acidic pH. As bile acids like DCA can induce DNA damage at neutral pH, suppressing the acidity of the refluxate will not completely remove its carcinogenic potential. The genotoxicity of DCA is however, ROS dependent, hence anti-oxidant supplementation, in addition to acid suppression may block DCA driven carcinogenesis in Barrett's patients.