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Biomedical subjects

Mehmet Melek

Publications and source records attributed to Mehmet Melek.

At least 19 recordsLinked to original sources
PubMed2007

The effect of successful electrical cardioversion on left ventricular diastolic function in patients with persistent atrial fibrillation: a tissue Doppler study.

BACKGROUND: Changes in mitral inflow and pulmonary venous flow after electrical cardioversion (ECV) in patients with persistent atrial fibrillation (AF) were showed in many former studies. In our study we investigated the effects of ECV on diastolic parameters by using tissue Doppler imaging (TDI) in patients with persistent AF. METHODS: Forty-one (24 women) consecutive patients underwent successful elective ECV for nonvalvular persistent AF, and maintained sinus rhythm for 1 month were enrolled to the study. Transthoracic echocardiography was applied to all patients before, 24 hours after and 1 month after ECV. Mitral annular TDI parameters were also measured with mitral inflow, pulmonary venous flow, and other standard echocardiographic measurements. RESULTS: No differences in peak myocardial early velocity (Em), deceleration time of Em, and myocardial isovolumic relaxation time measured from mitral lateral annulus before, 24 hours after, and one month after ECV were found. Peak myocardial late velocity measured 24 hours after ECV increased significantly at the end of 1 month. CONCLUSION: There were not any changes in LV diastolic function except restoration of atrial mechanical contraction following ECV in patients with persistent AF.

Aged↗
PubMed2006

Tissue Doppler evaluation of intraventricular asynchrony in isolated left bundle branch block.

BACKGROUND: The aim of this study was to evaluate normal subjects with isolated left bundle branch block (LBBB) using tissue Doppler imaging (TDI) for the presence of intraventricular asynchrony. METHODS AND RESULTS: For this purpose, 23 subjects with isolated LBBB were compared with age-matched asymptomatic healthy subjects without LBBB with respect to global ejection fraction (EF) and isovolumic contraction time (ICTm) in separate left ventricular segments. TDI evaluation revealed prolongation of the ICTm in all of the segments in the LBBB group. Moreover, the ICTm differed significantly in each segment in the LBBB group. The ICTm in the lateral segments were shown to be longer compared to the anteroseptal segments. CONCLUSION: Our results indicate the presence of intraventricular asynchrony in isolated LBBB. This fact may play a role in the decreased global EF and increased cardiac mortality in patients with isolated LBBB.

Bundle-Branch Block↗
PubMed2006

Impaired left ventricular filling in patients with essential hyperhidrosis: an echo-Doppler study.

Essential hyperhidrosis is a well recognized dermatologic and neurologic disorder, characterized by excessive sweating of the eccrine sweat glands. It is also associated with cardiac autonomic dysfunction because sympathetic fibers to eccrine glands of palms of the hand arise from stellate and upper thoracic ganglia, which also innervate the heart. In this study, we investigated cardiac function in patients with essential hyperhidrosis by conventional and tissue Doppler imaging methods. Eighteen subjects with essential hyperhidrosis and eighteen control subjects were included in this study. Pulsed-wave Doppler parameters of the left and right ventricles, which represent diastolic filling abnormalities, were obtained by conventional Doppler and tissue Doppler imaging. Isovolumetric relaxation time, isovolumetric contraction time, ejection time and myocardial performance index were also calculated. Mitral inflow peak early (E(M)) and late (A(M)) velocities and E(M)/A(M) ratio, which represent diastolic filling of left ventricle, were significantly lower in hyperhidrotic subjects than in controls. Also, mitral lateral annulus early and late velocities and early/late velocity ratio, reflecting diastolic filling of left ventricle, were significantly lower in hyperhidrotic subjects than those of controls. However, there were no differences between hyperhidrotic subjects and control subjects with regard to the other echocardiographic indices of left and right ventricle diastolic functions. In conclusion, decreased mitral inflow suggests left ventricle diastolic dysfunction in patients with essential hyperhidrosis. This indicates that hyperactivity of sympathetic nervous system in patient with hyperhidrosis may alter cardiac function in long term.

Adult↗
PubMed2006

Acute smoking-induced alterations in Doppler echocardiographic measurements in chronic smokers.

Acute effects of smoking on left ventricular function have been studied previously. However, effects on right ventricular function have not yet been investigated. In this study, we attempted to investigate, through a combination of conventional and tissue Doppler imaging (TDI), the acute effects of smoking on both left and right ventricular function in chronic smokers. Thirty chronic smokers (with smoking habits of > or =1 pack/day for 74 +/- 1.3 years) underwent a complete transthoracic echocardiographic examination (2-dimensional, pulsed-wave Doppler transmitral and transtricuspid recordings, and TDI recordings of mitral and tricuspid annular velocities) by 3.5-MHz sector transducer. Pulsed-wave Doppler indices of left and right ventricular diastolic function-such as mitral and tricuspid inflows, peak early (E) and late (A) velocities, and E/A ratios-were obtained by conventional Doppler and TDI. Echocardiographic indices of the left and right ventricles--including isovolumetric relaxation time, isovolumetric contraction time, ejection time, and myocardial performance index of right ventricle-were also measured before and 30 minutes after each subject smoked a cigarette. Both mitral and tricuspid inflow measurements changed significantly after smoking a cigarette. Among the TDI measurements, mitral lateral annulus and tricuspid lateral annulus (diastolic, but not systolic) velocities changed after smoking a cigarette. Also, the right ventricular myocardial performance index increased immediately after smoking a cigarette. We found that acute cigarette smoking impaired both left and right ventricular diastolic function in chronic smokers.

Adult↗
PubMed2005

Atresia of the colon.

BACKGROUND/PURPOSE: Colonic atresia (CA) is one of the rarest causes of neonatal intestinal obstructions, and no large series can be reported. Therefore, we did perform a retrospective clinical trial to delineate our CA cases and carry out a literature survey. METHODS: We reviewed the charts of CA cases treated in our center between 1992 and 2002. We aimed to collect all reported cases in Medline, and personal communications with the authors of published series were used to reach the missing data. RESULTS: The chart review revealed 9 newborns with CA treated in our center (6 cases of type III, 2 cases of type II, and 1 case of type IV). These accounted for 3.7% of all gastrointestinal atresias managed in our center. Of the CA cases, 3 were isolated and 6 had at least one or more associated congenital anomalies. The preferred surgical technique at the initial treatment of CA was performing a proximal stoma and distal mucous fistula in an average of postnatal 59.4 hours. The literature survey enabled us to reach 224 cases of CA, including our cases. CONCLUSIONS: Because of the low incidence of CA, delay in diagnosis and treatment may occur. The mortality is statistically higher when the surgical management is performed after 72 hours of age. However, the prognosis of CA is satisfactory if diagnosis and surgical management could be made promptly and properly.

Anastomosis, Surgical↗
PubMed2005

Cigarette smoking and heart rate variability: dynamic influence of parasympathetic and sympathetic maneuvers.

BACKGROUND: Cigarette smoking has been associated with increased activity of the sympathetic nervous system. In this study, we investigated cardiac autonomic function in heavy smokers and nonsmoker controls by analysis of heart rate variability (HRV). METHOD: Twenty-four long-term heavy smokers (men) and twenty-two nonsmoker subjects (hospital staff) were included to study. Time domain [mean R-R interval (RR), the standard deviation of R-R interval index (SDNN), and the root mean square of successive R-R interval differences (RMSSD)] and frequency domain [high frequency (HF) low frequency (LF), and LF/HF ratio] parameters of HRV were obtained from all participants after 15 minutes resting period in supine position (S), during controlled respiration (CR), and handgrip exercise (HGE) over 5-minute periods. RESULTS: Baseline SDNN and RMSSD values were found to be lower in smokers than in nonsmokers. (64+/-10 vs 78+/-22, P<0.05 and 35+/-12 vs 54+/-30 ms, P<0.05). Baseline LF/HF ratio was also found to be higher in smokers than in nonsmokers (1.3+/-0.6 vs 0.9+/-0.5 ms, P<0.05). The other HRV parameters including R-R interval, LF, and HF were not significantly different. During CR, expected increase in RR, SDNN, and RMSSD did not occur in smokers, while it did occur in nonsmokers. Most HRV indices were significantly affected by HGE in both groups. In addition, the duration of smoking was found to be inversely correlated with RMSSD and HF and positively correlated with LF/HF ratio. CONCLUSION: Vagal modulation of the heart is blunted in heavy smokers, particularly during a parasympathetic maneuver. Blunted autonomic control of the heart may partly be associated with adverse event attributed to cigarette smoking.

Adult↗
PubMed2005

Peripheral vascular endothelial function in essential hyperhidrosis.

BACKGROUND: Essential hyperhidrosis, a disorder of the eccrine sweat glands, is associated with sympathetic overactivity and the aim of the present study was to determine endothelium-dependent vasodilator function in patients with this condition. METHODS AND RESULTS: Using high-resolution ultrasound, the diameter of the brachial artery at rest and during reactive hyperemia (flow-mediated dilatation, %FMD endothelial-dependent stimulus to vasodilatation), as well as after sublingual administration of nitroglycerin (%NTG endothelium-independent vasodilatation) was measured in 18 subjects (mean age 27+/-5 years) with essential hyperhidrosis and 24 healthy control subjects (mean age 29+/-5 years). Baseline brachial artery diameter and FMD were comparable in both groups (BAD: 4.1+/-0.7 mm vs 4.3+/-0.5 mm (control), p = 0.8; FMD: 5.6+/-1.9% vs 6.7+/-2.2%, p=0.1). The time-averaged flow velocity during peak reactive hyperemia was similar in the 2 groups (75+/-11 cm/s vs 72+/-10 cm/s, p = 0.5), nor did NTG-induced dilatation in the patients with essential hyperhidrosis differ significantly from that in healthy control subjects (12.8+/-2.7% vs 14.0+/-3.6%, p = 0.3). CONCLUSION: These findings suggest that endothelium-dependent dilatation of large conduit arteries is preserved in essential hyperhidrosis and it seems to be a localized disorder of the eccrine sweat glands rather than a generalized disorder involving vascular endothelium.

Adult↗
PubMed2005

Comparison of the predictors for atrial rhythm disturbances between trained athletes and control subjects.

Atrial rhythm disturbances, particularly atrial fibrillation (AF), are frequently encountered in trained athletes. P wave dispersion (PWD) is a recent electrocardiographic (ECG) marker that reflects velocity of atrial impulse propagation. However, it remains unknown whether the P wave duration and PWD are different between athletes and sedentary controls. In this study we therefore determined the P wave duration and PWD, markers for conduction abnormalities, in trained athletes and controls. Fifty athletes and sex and age-matched 40 healthy sedentary controls were included in the study. All of the athletes were the members of a local athletic college and they were regularly maintaining their sportive activities; the duration of athletic competition was 7.7 +/- 3.3 years and the average athletic time was 10.1 +/- 1.6 hours/week. The 12-lead surface ECG was obtained from each subject in the supine position. The P wave duration was measured, and the difference between the maximum and minimum P wave duration was defined as the PWD. Distribution of sex, age, body mass index, blood pressure was similar in athletic groups and controls. Heart rate was significantly lower in the athletes than in the controls (66 +/- 7 vs 73 +/- 9 beats/min, p < 0.05). Maximum and minimum P wave durations were not statistically different in athletic group and controls (115 +/- 6 vs 114 +/- 4 ms and 74 +/- 8 vs 74 +/- 7 ms, respectively). In addition, PWD did not differ significantly in both groups (41 +/- 6 vs 40 +/- 7 ms, respectively). Thus, athlete's heart is not associated with prolonged P wave duration and increased PWD, indicating that P wave duration or PWD could not be used as a predictor for AF developed in trained athletes.

Adult↗
PubMed2004

Effect of smoking on endothelial function and wall thickness of brachial artery.

BACKGROUND: Impaired flow mediated dilatation (FMD) and increased wall thickness (WT) of the brachial artery have been associated with atherosclerosis and its risk factors. In this study we sought to determine brachial artery wall thickness in chronic smokers and the instantaneous effect of smoking on brachial artery endothelium dependent vasodilator function in smokers and non-smokers. METHOD AND RESULTS: Using a high-resolution ultrasound, WT of posterior brachial artery wall, the diameter of brachial artery at rest and during reactive hyperemia (FMD %), as well as after sublingual administration of nitroglycerine (nitroglycerine mediated dilatation (NMD) %) was measured in 20 smokers and 20 non-smokers. Wall thickness (WT) of the posterior brachial artery wall and the wall index (WI) were greater in smokers than non-smokers. The baseline brachial artery diameter was comparable in smokers and non-smokers. Flow mediated dilation (FMD) was found to be less in smokers than non-smokers. The NMD in smokers also did not differ significantly from that in non-smokers. Flow mediated dilation significantly reduced after smoking compared to baseline in both groups. However, NMD remained unchanged after smoking in both groups. CONCLUSIONS: Increased WT and impaired endothelium-dependent dilatation of brachial artery suggests that cigarette smoking disrupts vessel wall morphology long before atherosclerosis is manifest.

Administration, Sublingual↗
PubMed2004

Acute cigarette smoking-induced hemodynamic alterations in the common carotid artery--a transcranial Doppler study--.

BACKGROUND: Cigarette smoking has been shown to temporarily alter cerebral flow velocity and vasomotor reactivity, so the aim of this study was to assess the acute effects of smoking a single cigarette on the common carotid artery (CCA) hemodynamics in healthy nonsmokers. METHOD AND RESULTS: Using a 7.0 MHz linear transducer of a computed sonography system, the CCA hemodynamics, including the diameter of the left and right CCA, peak systolic velocity, maximum end-diastolic velocity, time-averaged maximum velocity pulsatility index, resistivity index, flow volume, diameter and area of the CCAs, were measured in 16 healthy nonsmokers before and immediately after smoking a cigarette. Compared with the baseline, heart rate and blood pressure significantly increased, the diameter, flow volume and area of each CCA were unchanged, and the pulsatility index and resistivity index were significantly altered after smoking. In addition, the peak systolic velocity, maximum end-diastolic velocity and time-averaged maximum velocity were significantly altered after smoking. CONCLUSIONS: Cigarette smoking significantly altered the CCA hemodynamics in nonsmokers, probably as a consequence of enhanced adrenergic activity.

Adult↗
PubMed2002

Cardiac troponin T and cardiac enzymes after external transthoracic cardioversion of ventricular arrhythmias in patients with coronary artery disease.

BACKGROUND: Serum levels of cardiac troponins after external cardioversion (ECV) for atrial fibrillation and atrial flutter are widely investigated, and no increases in cardiac troponin T (cTnT) levels have been reported. However, the effect of ECV on cardiac enzyme release may depend on the type of arrhythmias. Furthermore, ventricular tachycardia (VT) or ventricular fibrillation (VF) could cause release of cardiac enzymes after ECV due to underlying myocardial ischemia, myocardial dysfunction, or more pronounced hemodynamic deterioration during arrhythmia. AIM: The purpose of this study was to determine whether direct current (DC) shock may increase cardiac enzyme levels in patients with coronary artery disease undergoing ECV for VT or VF, so that diagnosis of acute myocardial infarction, which initially presents with VT or VF, can be excluded. METHOD AND RESULTS: We obtained measurement of cTnT, total creatine kinase (CK), and CK MB isoenzyme (CK-MB) activity before and after ECV in 27 patients (mean +/- SD age, 62 +/- 13 years) with induced VT or VF (22 patients) who required ECV during provocative electrophysiologic testing and who underwent ECV due to VT (5 patients) in the cardiology department. Blood samples were drawn before, and 4 h, 8 h, and 24 h after ECV. The total energy used was 630 +/- 375 J (range, 200 to 1,280 J). CK levels rose to the upper limit of reference range in seven patients (26%), and CK-MB activity was higher than the normal reference range in five patients (19%) after ECV. In contrast, cTnT concentrations remained within the normal range (< 0.1 micro g/L) in all patients. Peak CK and CK-MB activity levels strongly correlated with the total energy delivered. CONCLUSION: Elevation of cTnT level after an urgent DC shock strongly indicates the diagnosis of acute myocardial infarction presented with life-threatening arrhythmias, rather than myocardial damage caused by ECV.

Creatine Kinase↗