Development and performance assessment of new solar and fuel cell-powered oxygen generators and ventilators for COVID-19 patients.

In this study, a new solar-based fuel cell-powered oxygenation and ventilation system is presented for COVID-19 patients. Solar energy is utilized to operate the developed system through photovoltaic panels. The method of water splitting is utilized to generate the required oxygen through the operation of a proton exchange membrane water electrolyser. Moreover, the hydrogen produced during water splitting is utilized as fuel to operate the fuel cell system during low solar availability or the absence of solar irradiation. Transient simulations and thermodynamic analyses of the developed system are performed by accounting for the changes in solar radiation intensities during the year. The daily oxygen generation is found to vary between 170.4 kg/day and 614.2 kg/day during the year. Furthermore, the amount of daily hydrogen production varies between 21.3 kg/day and 76.8 kg/day. The peak oxygen generation rate attains a value of 18.6 g/s. Moreover, the water electrolysis subsystem entails daily exergy destruction in the range of 139.9-529.7 kWh. The maximum efficiencies of the developed system are found to be 14.3% energetically and 13.4% exergetically.

Development and analysis of a new renewable energy-based industrial wastewater treatment system.

In this research study, a new solar energy-based integrated system is developed for treating industrial brine wastewater. An integrated solar-powered evaporation and membrane-based water treatment technique is utilized. Both forced convection as well as falling film evaporators are incorporated to treat high-concentration rejected brine. The system performance is assessed through a comprehensive thermodynamic investigation at varying operating parameters. The energetic performance is evaluated to vary from 12.5% to 15.9% across the year. Furthermore, the peak efficiency in terms of exergy is found to be 11.1%. Also, the membrane-based wastewater treatment subsystem is found to entail an energetic performance of 73.3% and an exergetic performance of 34.6% in terms of efficiencies. Moreover, an energetic performance of 15.4% and an exergetic performance of 2.9% is found for the evaporation-based subsystem. The exergy destructions in each system component are evaluated and the power generation subsystem is determined to have the highest exergy destruction rate of 15.4 MW. To investigate the effects of varying design parameters and operating conditions on the system performance, several parametric studies are also performed.

Development and multi-objective optimization of a newly proposed industrial heat recovery based cascaded hydrogen and ammonia synthesis system.

The industrial flue gas emitted to the atmosphere is considered not only harmful to the environment but also a waste of plentiful resources of thermal energy. The thermal energy extracted from the industrial flue gas can be employed for multiple purposes. This study proposes a new configuration to integrate the thermal management of industrial flue gas for thermochemical copper-chlorine (Cu-Cl) cycle based ammonia synthesis. A reverse osmosis desalination unit is employed to supply the freshwater required by the thermochemical Cu-Cl cycle. To recover the heat from high-temperature oxygen stream, thermoelectric generators (TEGs) and organic Rankine cycle (ORC) are integrated with the proposed configuration to utilize the low-grade waste heat for power production. A portion of produced hydrogen through the thermochemical Cu-Cl cycle is supplied to the cascaded system for ammonia production. A double-stage cascaded ammonia synthesis system is integrated with the proposed configuration to achieve high fractional conversion. A multi-objective optimization using genetic algorithm is implemented to the proposed system using the MATLAB to investigate and determine the best-operating temperatures and pressures for the ammonia synthesis system. The proposed configuration produces 518.4 kmol/day of hydrogen and 226.8 kmol/day of ammonia. The overall exergetic and energetic efficiencies are found to be 28.7% and 40.8%. Moreover, the results obtained from the comprehensive sensitivity analyses are presented and discussed.

Approach to patients with chylothorax complicating pulmonary resection.

Mediastinal lymph node dissection, an important part of surgery for non-small cell lung cancer, is associated with a risk of chylothorax. Although mortality has significantly decreased in recent years, it still worries thoracic surgeons. In this report we reviewed our experience on chylothorax with 26 cases and assessed the outcomes after conservative and surgical approaches. Between January 2000 and June 2010, twenty-six patients developed chylothorax after pulmonary resection performed for non-small cell lung cancer. Initially, all cases were treated conservatively with cessation of oral intake and the application of talc poudrage. If the conservative method failed, a surgical approach was used, which consisted either of suturing the leak or of mass ligation. The mean age of patients was 56 ± 9.05 years, and 3 were female. Chylothorax was more common on the right side, in lobectomy cases, in cases with adenocarcinoma, and in patients with advanced stage lung cancer, but the difference did not reach statistical significance. Conservative treatment was successful in 19 of 26 (73 %) patients, four of whom had undergone pneumonectomy. Seven out of 26 cases (27%) required thoracotomy to control the chylous leak. Though thoracotomy was required mostly for the right side (6 right vs. 1 left, p = 0.15), and in patients who had had pneumonectomy as their first operation (4 patients vs. 3, p = 0.18), this did not reach statistical significance. No patient died as a result of surgical intervention. In conclusion, chylothorax is not rare after pulmonary resection performed for lung cancer. But it is not as dangerous as it used to be. Talc pleurodesis has increased the success of conservative management and minimized the need for surgical intervention. In cases of high output leak the surgeon should not hesitate to perform surgery. VATS can be performed instead of open surgery in suitable cases.

Energy and exergy analyses of a biomass-based hydrogen production system.

In this paper, a novel biomass-based hydrogen production plant is investigated. The system uses oil palm shell as a feedstock. The main plant processes are biomass gasification, steam methane reforming and shift reaction. The modeling of the gasifier uses the Gibbs free energy minimization approach and chemical equilibrium considerations. The plant, with modifications, is simulated and analyzed thermodynamically using the Aspen Plus process simulation code (version 11.1). Exergy analysis, a useful tool for understanding and improving efficiency, is used throughout the investigation, in addition to energy analysis. The overall performance of the system is evaluated, and its efficiencies become 19% for exergy efficiency and 22% energy efficiency while the gasifier cold gas efficiency is 18%.

Prognosis in patients with non-small cell lung cancer and satellite tumors.

BACKGROUND: Aim of the study was to identify factors affecting survival in patients with lung cancer and satellite tumors (ST). METHODS: Between 2001 and 2008, there were 102 patients with synchronous multiple lung cancers among the 1355 lung resections performed in lung cancer patients. Satellite tumors were found to be near the primary lung cancer (PLC) in 29 patients. RESULTS: Complete resection was achieved in all patients, and the 5-year survival rate was 52 %. The independent "T" stages of the PLCs and STs did not affect survival ( P = 0.98 and P = 0.54, respectively). A distance between the PLC and ST longer or shorter than 2, 3, or 4 cm also did not affect survival ( P = 0.78, P = 0.57, and P = 0.62, respectively). The survival of patients treated with adjuvant therapy was significantly higher than that of patients who did not receive adjuvant therapy ( P = 0.0043). CONCLUSIONS: Satisfactory survival was achieved after surgical therapy for non-small cell lung cancer associated with ST. While the PLC and ST characteristics and the distance between tumors did not affect survival rates, the introduction of adjuvant chemotherapy with/without radiotherapy positively affected survival.

Comparison between nebivolol and ramipril in patients with hypertension and left ventricular hypertrophy: a randomized open blinded end-point (PROBE) trial.

AIMS: To compare the effects of nebivolol and ramipril on left ventricular hypertrophy in hypertensive patients. MATERIALS AND METHODS: The study was conducted with a pre-randomised blinded endpoint (PROBE) design in which 106 patients with mild-to-moderate hypertension and left ventricular hypertrophy were randomised to ramipril (n = 52) or to nebivolol (n = 54) and treated for 39 weeks. The doses of ramipril and nebivolol were 2.5 and 5 mg/day, respectively. After 4-8 weeks, in patients with not normalised diastolic blood pressure, a thiazide diuretic was added (indapamide 2.5 mg or hydrochlorothiazide 12.5 mg/day). In the ramipril group, thiazide diuretic was added in 97% of subjects and in nebivolol group in 92%. The effect of treatment on left ventricular mass was assessed by two-dimensional guided M-mode transthoracic echocardiography, at baseline and at the end of the treatment. Left ventricular mass index (LVMI) was calculated and indexed to body surface area (g/m2) and height2.7 (g/height2.7). Blood pressure (BP) was measured at baseline, after 4, 8, 12, 24 and 39 weeks with a standard mercury sphygmomanometer. RESULTS: Both left ventricular mass (LVM) and mass index (LVMI) decreased significantly after treatment with ramipril (LVMI -14.8 g/m2, -7.3 g/height2.7; p < 0.001), and after treatment with nebivolol (LVMI -31.9 g/m2, -15.6 g/height2.7; p < 0.001). The difference between ramipril and nebivolol (-17.1 g/m2, -8.3 g/height2.7) with regards to reduction of LVMI was statistically significant (p < 0.001). No differences were observed between the two groups in terms of normalization of LVMI. Both drugs decreased BP similarly after 39 weeks of treatment CONCLUSIONS: The present study shows that both nebivolol and ramipril decrease LVMI. Nebivolol 5 mg/daily treatment reduced LVMI significantly more than ramipril 2.5 mg/daily. Both drugs similarly decreased BP during the treatment.

Mediastinal ectopic parathyroid adenoma: report of two cases successfully treated by VATS approach.

Ectopic parathyroid adenomas are the cause of approximately one in four cases of primary hyperparathyroidism (pHPT). Most ectopic parathyroid adenomas are located adjacent to the upper thymus gland and can be resected with a collar incision. In rare cases, however, adenomas located in the chest require a transsternalor transthoracic approach. Due to the high rate of morbidity with a sternotomy or thoracotomy, minimally invasive methods such as video-assisted thoracoscopic surgery (VATS) or video-assisted mediastinoscopic surgery (VAMS) are becoming increasingly popular. We present two cases with primary hyperparathyroidism due to mediastinal ectopic parathyroid adenoma that were successfully treated by VATS approach.

Elevated levels of C-reactive protein are associated with impaired coronary collateral development.

BACKGROUND: In vitro studies have shown that C-reactive protein (CRP) attenuates nitric oxide production and inhibits angiogenesis, which may result in impaired collateral development. The aim of this study was to investigate the association between high sensitivity CRP (hsCRP) levels and the extent of coronary collaterals. MATERIALS AND METHODS: We investigated the association between hsCRP levels and the extent of coronary collaterals according to the Rentrop classification in a cohort of 185 patients who had high-grade coronary stenosis or occlusion on their angiograms. RESULTS: Mean age was 62 years and 80% were males. Subjects with a higher grade of collaterals were significantly less likely to have diabetes mellitus (OR; 0.48, 95% and CI; 0.28, 0.83) or acute coronary syndrome (OR; 0.58, 95% and CI; 0.33, 0.99), but they were more likely to have higher number of vessels with significant stenosis (OR; 1.41, 95% and CI; 1.03, 1.93) and to have received statins (OR; 1.84, 1.09, 3.13). The mean hsCRP values reduced significantly as the Rentrop grades increased (trend, P = 0.0006). After adjusting for age, gender, statin use, clinical presentation with acute coronary syndrome, diabetes mellitus and the number of vessels with significant stenosis, each 10-unit increase in hsCRP values corresponded to a 31% reduced odds of having a higher collateral score (OR; 0.69, 95% and CI; 0.53, 0.90). CONCLUSIONS: Our findings indicate that elevated hsCRP levels are associated with a significant impairment in coronary collateralization. These data suggest a previously unrecognized mechanism through which inflammation may worsen cardiovascular outcomes.

Effect of losartan on circulating TNFalpha levels and left ventricular systolic performance in patients with heart failure.

BACKGROUND: Tumor necrosis factor alpha (TNFalpha) plays an important role in the pathophysiology of heart failure. Recent studies have shown a beneficial effect of losartan in these patients. However, the effect of losartan on TNFalpha levels in heart failure has not yet been studied. We evaluated the effect of losartan on circulating TNFalpha levels and ejection fraction (EF) in patients with congestive heart failure. METHODS: Forty patients with heart failure and EF < or = 40% were enrolled into the study. All of the patients have been given diuretic and digitalis therapy. Twenty patients were given losartan (50 mg/d) (Group I, 10 women, 10 men, 12 dilated cardiomyopathy, 8 ischemic heart disease, mean age 64.9 + 8.9), and another 20 patients were not given losartan because of hypotension or renal dysfunction (Group II, 13 men, 7 women, 10 dilated cardiomyopathy, 10 ischemic heart disease, mean age 61.2 +/- 10.5). EF was measured at the initial evaluation and on the fifteenth day of the therapy by echocardiographic examination using an acoustic quantification method. Circulating TNFalpha levels were also measured at the initial evaluation and on the fifteenth day of therapy by the ELISA method. RESULTS: Losartan significantly increased EF and decreased TNFalpha (EF increased from 29.4 +/- 7.3% to 36.0 +/- 8.5%, P < 0.001, and TNFalpha decreased from 39.2 +/- 37.4 pg/ml to 27.0 +/- 30.0 pg/ml, P < 0.05). Changes in TNFalpha levels and EF were not found to be correlated (r=-0.28, P=0.24). However, in the control group, EF and TNFalpha levels were similar at baseline and at the fifteenth day (EF 31.4 + 8.1% vs 31.7 +/- 7.8%, P=0.1, and TNFalpha 91.5 + 86.0 pg/ml vs 110.0 +/- 80.7 pg/ml, P=0.1, respectively). CONCLUSIONS: Losartan improves left ventricular systolic function and decreases TNFalpha level. The decreased TNFalpha level seems to be independent of EF.

Association between the severity of heart failure and the susceptibility of myocytes to apoptosis in patients with idiopathic dilated cardiomyopathy.

BACKGROUND: Bcl-2 proto-oncogene, an inhibitor of apoptosis and Bax proto-oncogene, an inducer of apoptosis play critical roles in the molecular circuit controlling apoptosis in cardiac muscle. The ratio of Bax to Bcl-2 proto-oncogene determines survival or death after an apoptotic stimulus. We speculated that susceptibility of myocytes to apoptosis determined as the Bax/Bcl-2 ratio might vary with the severity of heart failure. METHODS AND RESULTS: We studied immunohistochemically 108 endomyocardial biopsy specimens from 30 patients with idiopathic dilated cardiomyopathy (mild heart failure, n=14; moderate or severe heart failure, n=16) with the use of Bcl-2 and Bax monoclonal antibodies. The expression of each protein was determined semiquantitatively as the fraction of myocytes labeled with specific monoclonal antibodies using a digital morphometric analysis system. Patients with mild heart failure showed significantly increased Bax/Bcl-2 ratio than the patients with advanced heart failure (1.59+/-1.26 vs. 0.34+/-0.43, P=0.002). The expression of Bcl-2 was found to be independent of the severity of heart failure whereas the expression of Bax was significantly higher in patients with mild heart failure compared to the patients with moderate or severe heart failure (52.1+/-29.3 vs. 21.6+/-22.4%, P=0.005). Additionally, Bax/Bac-2 ratio was inversely correlated with the mitral E-interventricular septum distance, left ventricular end-systolic and end-diastolic diameter. CONCLUSION: The susceptibility of myocytes to apoptosis is significantly increased in the early phase of heart failure but it decreases with worsening of the disease due to depressed expression of Bax onco-protein. Increased myocyte susceptibility to apoptosis may have a role in the transition from mild heart failure to severe in patients with idiopathic dilated cardiomyopathy.

Predictive value of mitral annular calcification for the diagnosis of coronary artery disease in patients with dilated cardiomyopathy.

Mitral annulus calcification (MAC) is an independent predictor of coronary artery disease (CAD). The present study was designed to determine whether an association exists between MAC and CAD in patients with dilated cardiomyopathy. Among the 286 patients with MAC on echocardiographic examination who underwent coronary angiography, 55 patients with echocardiographic findings of dilated cardiomyopathy (group I) were compared to 60 age-matched controls without MAC and an echocardiographic diagnosis of dilated cardiomyopathy (group II) who underwent coronary angiography during the same time. There were no differences in echocardiographic findings between two groups. The prevalence of CAD was higher in group I when compared to group II (74% vs 28%, p<0.001). With regard to severity of CAD, two-vessel, three-vessel, and left main coronary artery disease were found to be significantly frequent in group I (p<0.001). Multivariate analysis revealed that MAC (p=0.001), diabetes mellitus (p=0.048), and history of anginal chest pain (p=0.009) are the independent predictors for the presence of CAD in patients with dilated cardiomyopathy. In conclusion, MAC may be a marker for the presence of coronary artery disease in patients with dilated cardiomyopathy.

The relation between transmitral early filling wave deceleration time and the recovery of atrial contractility after electrical cardioversion of atrial fibrillation.

BACKGROUND: Electrical cardioversion of atrial fibrillation (AF) to sinus rhythm is associated with transient left atrial dysfunction and this phenomenon may lead to thrombus formation and embolic stroke. Delay of atrial mechanical function recovery may be related to ventricular diastolic function. OBJECTIVE: This study examined the effects of left ventricular diastolic function as well as the multiple clinical factors on the recovery of atrial systolic function after cardioversion for atrial fibrillation. METHODS: A total of 44 patients (28 male, 16 female, 61+/-18 years) with chronic AF (> or =1 month) underwent electrical cardioversion. Deceleration time of early filling wave (pre-CV EDT) on transmitral inflow obtained by using Doppler echocardiography before cardioversion and serial transmitral inflow Doppler variables were recorded through a 1 week study period in all patients. Various clinical (age, gender, the duration of AF) and echocardiographic variables (pre-CV EDT, left atrial dimension, left ventricular ejection fraction) were tested for an association with peak atrial filling wave velocity (VA) on day 1, 3 and 7 after cardioversion. RESULTS: EDT measured before cardioversion had a strong linear correlation with peak VA on every echocardiographic evaluation after cardioversion (Regression coefficient (R)=0.69, P<0.001; R=0.78, P<0.001 and R=0.83, P<0.001, on day 1, day 3 and day 7, respectively). The effect of left ventricular ejection fraction on peak VA was weaker than those of EDT. The duration of AF showed an inverse association with the recovery of atrial function, but this lost on multivariate analysis. None of the other parameters significantly correlated with peak VA after cardioversion. CONCLUSION: The recovery of atrial mechanical function after cardioversion, as assessed by peak VA on transthoracic Doppler echocardiography is mainly associated with the left ventricular diastolic function as measured by EDT, whereas the left ventricular systolic function relatively a small effect on this outcome. The duration of AF does not have any association with peak VA, possibly if it is chronic.

Methylenetetrahydrofolate reductase gene polymorphism and risk of premature myocardial infarction.

BACKGROUND: Elevated plasma homocysteine level is an independent risk factor for cardiovascular disease. A common mutation (nucleotid 677C-T) in the gene coding for methylenetetrahydrofolate reductase (MTHFR) has been reported to reduce the enzymatic activity of MTHFR and is associated with elevated plasma levels of homocysteine, especially in subjects with low folate intake. HYPOTHESIS: Methylenetetrahydrofolate reductase T/T genotype may be a risk factor for premature MI in Turkish population who are known to have low folate levels. METHODS: The study group was comprised of 96 men (aged <45 years) with premature myocardial infarction (MI) and 100 age- and gender-matched controls who had no history or clinical evidence of coronary artery disease (CAD) and/or MI. DNA was extracted from peripheral blood and genotypes were determined by polymerase chain reaction, restriction mapping with HinfI, and gel electrophoresis. Conventional risk factors for CAD were prospectively documented. RESULTS: Allele and genotype frequencies among cases and control subjects were compatible with Hardy-Weinberg equilibrium. The frequencies of T/T, C/T, and C/C genotypes among patients with MI and control subjects were 15.6, 40.6, and 43.8%, and 5, 35, and 60%, respectively. Multivariate analyses identified smoking, MTHFR C/T polymorphism, diabetes mellitus, family history of CAD, and hypertension as the independent predictors of premature MI. Defining patients with non-T/T genotype (C/C and C/T combined) as reference, the relative risk of MI for subjects with T/T genotype was 5.94 (95% confidence interval: 1.96-18.02, p = 0.0016). CONCLUSIONS: Our findings suggest that C677T transition in the MTHFR gene may be a risk factor for premature MI in Turkish men.

Is there any effect of chronobiological changes on coronary angioplasty?

AIMS: We hypothesized that If there is a chronobiologic variation in the development of acute ischaemic events which is mainly attributed to the tendency for thrombus formation in the morning hours, same time dependent variations must also be seen in the development of ischaemic events after percutaneous transluminal coronary angioplasty (PTCA) and PTCA with stent implantation. METHODS: Enrolled in this study were 349 consecutive patients with single vessel disease and undergoing elective single vessel angioplasty. Patients had been observed for the development of immediate postprocedural ischaemic events. Working hours of our laboratory were divided into 2-hourly intervals in order to define the ending time of procedure. Analysis of acute complications was carried out according to the ending time of procedure. RESULTS: There was no difference with regard to clinical presentation, but patients who had complications had higher blood cholesterol level (P < 0.05). Patients with stent implantation had more adverse events than the PTCA group, but this difference did not reach the statistical significance (P = 0.07). The time interval between 10:30 a.m.-12:30 p.m. was found to be an independent risk factor for the negative outcomes (P = 0.043, Relative Risk 4838). CONCLUSION: The results of our study have demonstrated that postprocedural complications after angioplasty is related to the procedure time These patients may be observed more closely for the development of immediate postprocedural ischaemic events.

Hyperhomocysteinemia and restenosis.

OBJECTIVE: This study was undertaken to assess the effect of plasma homocysteine level on angiographic restenosis 6 months after coronary angioplasty. METHODS: The plasma homocysteine level was measured in 100 consecutive patients at the time of coronary angioplasty, 56 patients who attended a 6-month follow-up angiogram being enrolled to the study; the 44 patients without a control coronary angiogram were not enrolled. Patients with and without angiographic restenosis were designated as groups A (n = 34) and B (n = 22) respectively. RESULTS: The baseline demographic (groups A and B), angiographic (groups A and B) and procedural characteristics were similar in both groups. The mean plasma homocysteine level (SD) was 15.2 (7.7) and 11.1 (2.5) mumol/l in groups A and B respectively (P = 0.007; 95% CI -6.9 to -1.1). With respect to the plasma homocysteine level, the upper and the lower thirds were compared by binary logistic regression (the lower third homocysteine level being < 10.6 mumol/l and the upper third homocysteine level > 14.1 mumol/l). The angiographic restenosis rate for the lower and upper tertiles was 47.4% and 89.5% respectively (P = 0.01; OR = 9.4; 95% CI 1.6-52.7). After adjustment for age and sex, the statistical significance did not change (P = 0.013; OR = 9.43; 95% CI 1.6-54.9). Even after adjustment for age, sex, smoking, hypertension, hypercholesterolemia, and diabetes mellitus, there was a statistically significant difference between the upper and lower tertiles (P = 0.008; OR = 41.3; 95% CI 2.6-635). CONCLUSION: Increased plasma homocysteine level and diabetes mellitus were independent risk factors for angiographic restenosis after percutaneous transluminal coronary angioplasty and coronary stenting.

A recurrent right heart thrombus in a patient with Behçet's disease.

We report the case of a patient who was admitted to the immunology unit of our medical facility. The patient had a history of recurrent oral ulcers, low-grade fever, weight loss, and fatigue. Echocardiographic examination revealed a right ventricular mass that was initially thought to be a myxoma in an unusual location, and the patient was sent to surgery. Surgery revealed the mass to be a thrombus. After 5 months of anticoagulation therapy, the patient was readmitted to our institution with the same complaints, and a right atrial thrombus was found on echocardiographic examination. After a careful reevaluation of the patient's history and episodes of recurrent oral and genital ulcers, as well as the papulopustular lesions found on his first admission to hospital, Behçet's disease was diagnosed. The patient received thrombolytic therapy with a regression of thrombus, and continued with immunosuppressive and anticoagulation therapy. Five months later, echocardiographic examination showed complete disappearance of thrombus.

Lengthening of intraatrial conduction time in atrial fibrillation and its relation with early recurrence of atrial fibrillation.

Intraatrial conduction delay in atrial fibrillation (AF) that is considered a component of atrial electrical remodeling has been demonstrated previously in experimental models and it is considered an important factor for the induction or stabilization of AF. However, it is not known if this phenomenon exists in human AF. The present study aimed to compare intraatrial conduction time (IACT) in patients with chronic atrial fibrillation who were converted to sinus rhythm and a matched control group, and to investigate its relation with early AF recurrence. Seventeen patients with chronic AF (mean duration of 20.71+/-16.35 months) were enrolled in the study (7 males, 10 females, 63+/-8 years). An age and sex matched control group (n=12) consisted of patients with sinus rhythm who underwent electrophysiological study (EPS). None of the patients were on any antiarrhythmic treatment during the procedures. Cardioversion was performed via external DC cardioversion. Eight patients in the control group were delivered a DC shock because of induced ventricular tachycardia during EPS. IACT was defined as the interval between the onset of P wave surface ECG and the beginning of A wave at high right atrium (IACT 1) and low right atrium (IACT 2). Additionally, the interval between A wave at high right atrium and low right atrium was measured (IACT 3). Patient characteristics such as age, sex and echocardiographic variables were not different between the AF group and the control group. Heart rate after cardioversion was found to be similar between the two groups. Total delivered energy was significantly higher in the AF group than in the control group (464.47+/-165.82 joules vs. 315.00+/-27.77 joules, p<0.001). IACT 1 (15.30+/-7.61 msec vs 8.50+/-5.29 msec, p<0.02 ), IACT 2 (45.25+/-836 msec vs 26.44+/-10.45 msec, p<0.001) and IACT 3 (26.9+/-8.26 msec vs. 18.67+/-10.05, p<0.05) significantly lengthened in the AF group after maintenance of sinus rhythm compared to the control group. There were 6 early AF recurrences during the 1 week follow-up period. Multivariate analysis, revealed IACT 2 and IACT 3 were significantly different between the control group, the patient with recurred AF and the patients with maintained sinus rhythm. Post-hoc analysis revealed that IACT 2 and IACT 3 significantly lengthened in the patients with recurred AF compared to both the control group and patients with maintained sinus rhythm. On the other hand, only IACT 2 patients with maintained sinus rhythm were found to be higher than those of the control group. The present study indicated that intraatrial conduction was disturbed in patients with AF, a finding which is consistent with those of previous experimental studies. Additionally, such a phenomenon may be a risk factor for the early recurrence of AF after cardioversion to sinus rhythm.