Biomedical subjects

Giray Kabakci

Publications and source records attributed to Giray Kabakci.

11 recordsLinked to original sources

PubMed2006

Coronary artery bypass grafting is associated with a significant worsening of QT dynamicity and heart rate variability.

BACKGROUND: Imbalance in autonomic nervous system and impaired myocardial repolarization has been shown to increase the risk for arrhythmias in patients with coronary artery disease. This study evaluated the effects of coronary artery bypass grafting (CABG) on heart rate variability and QT interval dynamicity in subjects with coronary artery disease undergoing elective CABG surgery. METHODS: The study group consisted of 68 consecutive patients (mean age +/-SD: 61 +/- 9 years) with coronary artery disease who underwent elective CABG. Twenty-four-hour Holter monitoring was performed 2-5 days before cardiac surgery and was repeated 10 days after CABG. ELATEC holter software was used to calculate heart rate variability and QT dynamicity parameters. All subjects had a complete history, laboratory examination and transthoracic echocardiography. RESULTS: All patients had beta-blocking agent medication pre- and postoperatively. Standard deviation of all NN intervals for a selected time period, square root of the mean of the sum of the squares of differences between adjacent RR intervals, the proportion of differences in successive NN intervals greater than 50 ms, normalized low-frequency power, and normalized high-frequency power were significantly decreased after CABG surgery, whereas low-frequency/high-frequency ratio was significantly increased after CABG. QT/RR slopes over 24 h were significantly increased after CABG surgery for QT end and QT apex (QTapex/RR: 0.16 +/- 0.13 vs. 0.28 +/- 0.19, p < 0.001; QTend/RR: 0.18 +/- 0.13 vs. 0.36 +/- 0.23, p < 0.001). CONCLUSION: This prospective study showed for the first time that CABG was associated with a significant worsening of heart rate variability and QT dynamicity parameters in the postoperative period.

Adrenergic beta-Antagonists↗

PubMed2006

The effect of VVI pacing on P-wave dispersion in patients with dual-chamber pacemakers.

The incidence of atrial fibrillation is higher in patients with VVI pacing mode than DDD pacing mode, but the likely mechanism is not clearly understood. We aimed to evaluate whether short-term VVI pacing increases inhomogeneous atrial conduction by using P-wave dispersion. Forty-seven patients (32 men, 15 women, mean age 54 +/- 13 years) with DDD pacemakers were enrolled in this study. Twelve-lead surface ECGs were obtained in all patients during VDD pacing after an observation period of 1 week. The mode was then changed to VVI and 12 lead surface ECGs were obtained after another 1-week observation period. P-wave durations were calculated in all 12 leads in both VDD and VVI pacing modes. The difference between the maximum and the minimum P-wave duration was defined as the P-wave dispersion (PWD = P(max) - P(min)). P-wave maximum duration (P(max)) calculated in VVI pacing mode was significantly longer than in VDD pacing mode (128 +/- 19 vs 113 +/- 16 ms, P < 0.001). There was no significant difference in the P-wave minimum durations (80 +/- 13 ms vs 79 +/- 12 ms, P = 0.7) between VVI pacing and VDD pacing. The P-wave dispersion value was higher in the VVI pacing mode than in the VDD pacing mode (48 +/- 8 ms vs 34 +/- 7 ms, P < 0.001). Short-term VVI pacing induces prolongation of P(max) and results in increased P-wave dispersion, which might be responsible for the development of atrial fibrillation more frequently in these patients than in those with the VDD pacing mode.

Adult↗

PubMed2006

Value of 99mTc-methoxyisobutylisonitrile (99mTc-MIBI) gated SPECT for the detection of silent myocardial ischemia in hemodialysis patients: clinical variables associated with abnormal test results.

BACKGROUND: Although coronary artery disease is a major cause of mortality and morbidity in patients undergoing hemodialysis, there is no accurate diagnostic strategy for these patients. AIM: To assess the value of 99mTc-methoxyisobutylisonitrile (99mTc-MIBI) gated single-photon emission computed tomography for the detection of silent myocardial ischemia in patients undergoing hemodialysis and to evaluate the clinical variables associated with abnormal test results. METHODS: Thirty-one asymptomatic patients undergoing hemodialysis (20 men, 11 women), with a mean age of 45 years (range, 25-75 years), were included in the study. Serum electrolytes, creatinine, homocysteine and adhesion molecules were measured prior to dialysis. Ambulatory blood pressure, carotid intima-media thickness measurements, echocardiography and stress 99mTc-MIBI imaging were performed in all patients, whereas coronary angiography was performed only in patients with abnormal myocardial perfusion scintigraphy and/or echocardiography. RESULTS: Gated myocardial perfusion scintigraphy results were abnormal in nine patients (29%) and coronary angiography was abnormal in six patients. After a median follow-up of 20 months (range, 14-28 months), nine patients experienced a cardiac event. Seven of the nine patients (78%) with abnormal myocardial perfusion scintigraphy suffered a cardiac event, compared with only two of 22 patients (9%) with normal myocardial perfusion scintigraphy (P<0.0001). Patients with abnormal perfusion scintigraphy had higher serum C-reactive protein, homocysteine and adhesion molecule levels and the duration of hemodialysis was significantly longer. CONCLUSION: In asymptomatic hemodialysis patients, gated myocardial perfusion scintigraphy is a safe and non-invasive screening technique for the detection of coronary artery disease and for predicting future cardiac events. The presence of ischemia correlates significantly with markers of inflammation. The discordant results (abnormal myocardial perfusion scintigraphy/normal coronary angiography) can be attributed to angiographically unrecognized occult atherosclerotic changes and abnormal vasodilatation capacity of the coronary circulation.

Adult↗

PubMed2006

QT dispersion increases with aging.

BACKGROUND: Age-related changes in cardiovascular system are well-known. Arrhythmias in elderly patients constitute most of the urgencies, consultations, or hospitalizations. QT dispersion (QTd) is a simple noninvasive arrhythmogenic marker to demonstrate the electrical instability of the heart. The aim of this study was to investigate how QTd changes with increasing age by calculating the QTd in the elderly and younger subjects. METHODS: One hundred and forty-six consecutive subjects (62 males and 84 females; age range: 18-82 years) were enrolled in the study. Sixty-seven of the subjects were 65 years and over (mean age, 70 +/- 4), 79 were younger than 65 (mean age, 37 +/- 11). A 12-lead ECG was recorded. The longest and the shortest QT intervals were measured manually on these ECG recordings. QTd was calculated from the formula, QTd = QTmax - QTmin. RESULTS: Demographic features were similar between the two groups. QTd of the elderly group was found to be significantly higher than the younger group (35.6 +/- 15.6 in elderly, 24.2 +/- 12.4 in younger group, P < 0.001). A positive relationship was found between QTd and age (r = 0.415, P < 0.001). QTd was greater in female than in male (31.9 +/- 16.7 ms vs 26.0 +/- 11.3 ms, respectively, P = 0.018). CONCLUSIONS: Our study shows that QTd increases with advancing age. We think that long-term follow-up of these patients would be useful to show if there is any relationship between the clinical outcomes and the increase in QTd.

Adolescent↗

PubMed2006

Heart-type, fatty-acid binding protein can be a diagnostic marker in acute coronary syndromes.

OBJECTIVES: Chest pain is one of the most common complaints among patients admitted to emergency departments. Cardiac troponins, CK-MB and myoglobin, which are used routinely in the diagnosis of acute coronary syndrome (ACS), are not elevated in the initial hours of ACS--precluding their usefulness in the early diagnosis. The aim of this study is to determine the efficacy of H-FABP compared to myoglobin and CK-MB in the early diagnosis of ACS. METHODS: Sixty-seven patients with ACS were enrolled in the study. An initial blood sample was obtained for CK-MB, cTnT, myoglobin and H-FABP. At the fourth, eighth, and 12th hours, repeat ECGs and cardiac enzyme samples were obtained. H-FABP test was repeated at the fourth hour. RESULTS: H-FABP has sensitivity equal to that of CK-MB and superior to that of myoglobin (97.6%, 96.7%, 85.4%, respectively) on the first hour. This trend extends to the fourth hour of myocardial injury as well. H-FABP was more specific than CK-MB, myoglobin and troponin T at the first hour (38.5%, 34.6%, 34.6%, 23.1%, respectively), whereas its specificity at the fourth hour was equal to those of CK-MB and troponin T and exceeded that of myoglobin. CONCLUSIONS: It can be suggested that in patients with an initial diagnosis of ACS and within 20 hours from symptom onset, H-FABP levels may be measured. For this purpose, point-of-care H-FABP test may be utilized, which has the advantage of bedside testing and rapid test results.

Acute Disease↗

PubMed2005

Melatonin levels decrease in type 2 diabetic patients with cardiac autonomic neuropathy.

The present study has been designed to determine melatonin levels in type 2 diabetic patients and test the relationship between the autonomic nervous system and melatonin dynamics. Thirty-six type 2 diabetic patients and 13 age-matched healthy subjects were recruited for the study. Circadian rhythm of melatonin secretion was assessed by measuring serum melatonin concentrations between 02:00-04:00 and 16:00-18:00 hr. Melatonin dynamics were re-evaluated with respect to autonomic nervous system in diabetic patients with autonomic neuropathy who were diagnosed by the cardiovascular reflex tests, heart rate variability (HRV), and 24-hr blood pressure monitoring. Nocturnal melatonin levels and the nocturnal melatonin surge were low in the diabetic group (P = 0.027 and 0.008 respectively). Patients with autonomic neuropathy revealed decreased melatonin levels both at night and during day when compared with healthy controls (P < 0.001 and 0.004 respectively) while the melatonin dynamics were similar to controls in patients without autonomic neuropathy. Nocturnal melatonin level was positively correlated with nocturnal high and low frequency components of HRV (P = 0.005 and 0.011 respectively) and systolic and diastolic blood pressures at night (P = 0.002 and 0.004 respectively) in patients with autonomic neuropathy. We found a negative correlation between nocturnal melatonin levels and the degree of systolic blood pressure decrease at night (r = -0.478, P = 0.045). As a conclusion this study has shown that circadian rhythm of melatonin secretion is blunted in type 2 diabetic patients and there is a complex relationship between various components of autonomic nervous system and melatonin secretion at night. Among the patients with autonomic neuropathy those with more preserved HRV and the systolic nondippers (<10% reduction in blood pressure during the night relative to daytime values) have more pronounced melatonin surge at night.

Autonomic Nervous System Diseases↗

PubMed2005

Effect of irbesartan monotherapy compared with ACE inhibitors and calcium-channel blockers on patient compliance in essential hypertension patients: a multicenter, open-labeled, three-armed study.

OBJECTIVES: This multicenter, three-armed, open-labeled study investigated patient compliance of patients receiving irbesartan, angiotensin-converting enzyme (ACE) inhibitors or calcium-channel blockers (CCB) for essential hypertension for a 6-month period. Patients were either newly diagnosed or switched from existing antihypertensive medication due to lack of efficacy or side-effects. METHODS: Patients were started monotherapy with irbesartan (n=377), ACE inhibitors (n=298) or CCB (n=308) and were reevaluated on 1st, 3rd, and 6th months of the treatment. The primary endpoint was patient compliance, assessed by proportion of patients who had taken their study medication every day. Efficacy was recorded as mean reductions in blood pressure and the proportion of patients whose blood pressure normalized. Tolerability was assessed by reported adverse events. RESULTS: Significantly more patients receiving irbesartan had complied with study medication after 3 and 6 months of treatment than ACE inhibitors or CCB. Significantly fewer patients receiving irbesartan needed to change their antihypertensive medication. All three study treatments exhibited similar efficacy profiles, but irbesartan had significantly less adverse events. CONCLUSIONS: This study demonstrated that patient compliance to irbesartan was significantly superior to other study treatments. Irbesartan is therefore a suitable first-line therapy for essential hypertension in everyday clinical practice.

Adult↗

PubMed2004

The signal-averaged P-wave duration is longer in hypertensive patients with history of paroxysmal atrial fibrillation as compared to those without.

BACKGROUND: Onset of atrial fibrillation in hypertensive patients is usually associated with a high occurrence of cardiovascular complications. Therefore, it is important to assess non-invasively the risk of developing paroxysmal atrial fibrillation (PAF) in hypertensive patients during sinus rhythm. This study was undertaken to determine if hypertensive patients with history of PAF could be identified while in sinus rhythm by measurement of signal-averaged ECG P-wave duration. METHODS: Signal-averaged electrocardiography (SAECG) P-wave recording was performed in 44 hypertensive patients (30 men and 14 women; mean age 60+/-11 years, group A) who had a history of paroxysmal AF and in 50 hypertensive patients without history of AF (33 men and 17 women; mean age 57+/-12, group B). All patients were also evaluated by using echocardiography to measure left ventricular ejection fraction (LVEF) and left atrial diameter (LAD). RESULTS: SAECG P-wave duration was found to be significantly higher in group A than in group B (146+/-14 ms vs. 128+/-11 ms, p<0.001). Left atrial diameter was not significantly different (40.1+/-3.4 mm vs. 39.3+/-3.0 mm, p>0.05), whereas LVEF was significantly lower in group A than group B (63+/-5% vs. 67+/-4%, p=0.03). There was a correlation between SAECG P-wave duration and age (r=0.32, p<0.05). In univariate analysis, SAECG P-wave duration and LVEF were significant predictors of PAF, but only SAECG P-wave duration remained a significant independent predictor of PAF in multivariate analysis. CONCLUSION: The results of this study indicate that hypertensive patients with history of PAF can be detected while in sinus rhythm by signal-averaged ECG P-wave duration.

Adult↗

PubMed2002

Angioplasty induced myocardial ischaemia prolongs the signal-averaged P-wave duration in single vessel coronary artery disease.

Aims The P-wave duration (PWD) has been shown to prolong in conditions associated with elevated left ventricular end-diastolic and left atrial pressures, which also increase during transient coronary artery occlusions such as angioplasty. The aim of this study was to investigate the effects of angioplasty-induced myocardial ischaemia on signal averaged PWD in patients undergoing coronary angioplasty. Methods Eighty-four consecutive adult patients with single-vessel coronary artery disease undergoing elective coronary angioplasty were included. Duration of the P wave before and during coronary angioplasty were evaluated using signal averaged P-wave analysis. Patients were classified in groups according to the artery occluded, as left anterior descending (LAD) Group, right coronary artery (RCA) Group or Others Group (which included obtuse marginal, circumflex or diagonal). Results Patients included in the LAD, RCA and Others groups were similar with respect to clinical characteristics. The mean PWD at baseline was similar in all lesions (P>0.05), whereas mean PWD at inflation was significantly longer in LAD Group compared with RCA (126.1 +/- 9.5 ms vs 118.7 +/- 10.4 ms, P=0.007) and Others (126.1 +/- 9.5 ms vs 116.3 +/- 8.6 ms, P<0.001). The PWD during balloon inflation was significantly prolonged in all groups compared with baseline levels (LAD Group 126.1 +/- 9.6 ms vs 109.7 +/- 8.0 ms; RCA Group 118.7 +/- 10.4 ms vs 108.3 +/- 8.4 ms and Others Group 116.3 +/- 8.6 ms vs 109.7 +/- 6.0 ms, all P values <0.001). Conclusion Signal-averaged PWD significantly increases during single-vessel coronary angioplasty. This increase is more pronounced for LAD lesions. However, the clinical implications of P-wave prolongation during balloon angioplasty and the value of PWD as a measure of ischaemia remains to be clarified.

Angioplasty, Balloon, Coronary↗

PubMed2002

Effects of menstrual cycle on cardiac autonomic innervation as assessed by heart rate variability.

OBJECTIVE: The aim of the study was to investigate the effects of menstrual cycle on cardiac autonomic function parameters in young healthy women by means of heart rate variability (HRV). METHODS: Forty-three nonobese regularly cycling women (age 29 +/- 6, range 20-38) were enrolled. Recordings for HRV analysis were obtained during the two phases of the menstrual cycle when the estrogen and progesterone levels peaked (follicular phase 11 +/- 1 days and luteal phase 21 +/- 1 days from the start of bleeding). Power spectral analysis of HRV was performed to calculate the low frequency peak (LF, 0.04-0.15 Hz), high frequency peak (HF, 0.15-0.40 Hz), LF in normalized unit (LF nU), HF in normalized unit (HF nU), and LF/HF ratio during the two phases of menstrual cycle. RESULTS: The heart rates, LF and HF, were similar in both phases (P > 0.05). A significant increase was noted in the LF NU in the luteal phase compared to follicular phase of the menstrual cycle (P = 0.014), whereas a tendency for increased HF NU was observed in the follicular phase (P = 0.053). Furthermore, LF/HF ratio was significantly higher in the luteal phase compared to follicular phase (2.1 +/- 1.5 vs 1.6 +/- 0.9, P = 0.002), suggesting increased sympathetic activity in the luteal phase. CONCLUSION: We concluded that regulation of autonomic tone is modified during menstrual cycle. The alteration in the balance of ovarian hormones might be responsible for these changes in the cardiac autonomic innervation.

Adult↗

PubMed2002

Effects of hormone replacement therapy on plasma homocysteine and C-reactive protein levels.

In order to investigate the effect of hormone replacement therapy (HRT) on plasma homocysteine and C-reactive protein (CRP) levels 46 healthy postmenopausal women were prospectively enrolled. HRT, which was either 0.625 mg/day conjugated equine estrogen (CEE) plus 2.5 mg/day medroxyprogesterone acetate (MPA) or 0.625 mg/day CEE alone were administered. After 6 months, estrogen alone significantly increased serum CRP concentrations (p = 0.039), however, estrogen plus progesterone therapy did not significantly alter serum CRP levels. Both regimens significantly decreased plasma homocysteine levels (CEE group p = 0.034, CEE+MPA group p = 0.007). It was concluded that the reduction in plasma homocysteine levels with both regimens might contribute to the cardiovascular benefit of HRT and the CRP raising effect of estrogen might be partially prevented by the addition of progesterone.

Adult↗