Methods
This study included a total of 170 cross-sectionally chosen CKD patients older than 18 years belonging to our clinic between September 2016 to July 2017. The definition and the diagnostic criteria for chronic kidney disease were proposed in the K/DOQI guidelines: estimated glomerular filtration rate (GFR ml/min/1.73 m2) calculated by the MDRD formula (18). Patients were divided into five groups according to their GFR values (Stage-I=76 (GFR>90), Stage-II=39 (GFR=60-89), Stage-III=25 (GFR=30-59), Stage-IV=15 (GFR=15-29), Stage-V=15 (GFR<15)). Patients with the following conditions were excluded from the study: uncontrolled hypertension, left ventricular systolic dysfunction, valvular pathology, any effusion, aortic aneurysms, acute coronary syndromes, chronic lung disease, hepatic dysfunction, known malignancy, systemic infection or inflammatory disorders, and dialysis application. Informed consent was obtained from all patients before the study. This study was performed according to the principles stated in the Declaration of Helsinki and was approved by the local ethics committee of the Van Training and Research Hospital.
Physical examinations, including anthropometric measurements, history, and basic laboratory tests, were performed. After an overnight fast of at least 8 hours, blood samples were taken from the antecubital vein with an atraumatic puncture and sent to the laboratory for analysis. Routine electrocardiography (ECG) was recorded in each patient. Each patient underwent complete transthoracic echocardiography following the American Society of Echocardiography guidelines. The transthoracic echocardiography was performed at rest, with the patient in the left lateral decubitus position, using an echocardiographic device (Vivid S6, General Electric, Horton, Norway) with a 3.0-MHz transducer. Two experienced cardiologists blinded to clinical data performed the echocardiography. Echocardiographic images were also recorded, and offline measurements were performed.
Color M-mode Doppler recordings were obtained from the suprasternal window in the supine position. The cursor was placed parallel to the main direction of flow in the descending aorta. The Nyquist limit was adapted to 30–50 cm/s, switching to the M-mode with a recorder sweep rate of 200 mm/s. If the slope of the flame was unclear, baseline shifting was used to change the aliasing velocity until a clear delineation of the velocity slope was obtained (Figure 1). AVP was then calculated by dividing the distance between the points corresponding to the beginning and end of the propagation slope by the duration between the corresponding time points. Thus, AVP corresponds to the velocity at which the flow is propagating down the artery. The mean of at least three measurements was recorded as the AVP.
The EFT was measured on the free wall of the right ventricle from the parasternal long-axis view, using the aortic annulus as an anatomic reference. The thickness of the free right ventricular wall was measured at the end-systolic period. When space was found without an echogenic view between visceral pericardium and myocardium, it was estimated as epicardial fat. To measure EFT, the thickest area was chosen to measure, preferably the right supraventricular area (Figure 2). The average value of the three cardiac cycles was noted.
Carotid arteries were evaluated using a Logiq 7 (General Electronic, Waukesha, WI, USA) with a 7.5-MHz transducer. All examinations were performed by two experienced radiologists who were blinded to the patients’ clinical information. Measurements were performed for the right and left carotid arteries and involved primary transverse and longitudinal scanning of the common carotid artery, bifurcation, and internal carotid. The patient was lying in a supine position with their head directed away from the side of interest and neck slightly extended. The CIMT was measured on the far wall, 1 cm from the bifurcation of the common carotid artery, as the distance between the lumen intima interface and the media-adventitia interface. The CIMT was measured from the frozen frame of a suitable longitudinal image. At least three measurements were performed on both sides, and the average measurement was taken as the CIMT. All measurements were made at a plaque-free site.