"Impedance Cardiography (ICG) and Echo Cardiography Datasets "

"The signals were recorded at Hardas Heart Care (Pune, Maharashtra, India), following approval of the protocol by the hospital's Ethics Committee. The subjects were recruited, without gender and age balancing, from among the persons visiting the hospital for post-operative treatment, diagnosis, or health checkup. They were informed about the objectives of the study and the signal-recording procedure, and those willing to participate signed the consent form. Participation did not involve any monetary benefit or cost for the subjects. The subjects with normal health had no known history of cardiovascular disorders and were screened by a cardiologist on the basis of physical examination and ECG report. The subjects with cardiovascular disorders were the patients undergoing post-operative treatment or had a history of cardiovascular disorders. They were screened for suitability to participate in the study by the concerned cardiologist. The gender, age, height, and weight of the subjects were noted. The recordings were carried out over 13 months.The ICG signals were recorded using BHIC-2000 Impedance Cardiograph^ from Bio-Impedance Technology (Chapel Hill, NC, USA). The impedance sensing was carried out using four-electrode configuration with Ag-AgCl dispos able ECGspotelectrodes. The outer two electrodes were used for injecting the excitation current and the resulting voltage was picked up across the inner two electrodes. The electrode placement is shown in Fig. 2. The upper current electrode was placed above the suprasternal notch on the front of the neck, with the lower one placed below the xiphoid process on the left lateral side of the thorax. The upper voltage electrode was placed at the base of the neck below the upper current electrode and the lower voltage electrode was placed at the level of the xiphoid process on the left lateral side of the thorax above the lower current electrode. The distance between the voltage sensing electrodes was noted. The instrument used 1 mA excitation current of 100 kHz and provided analogue output signals corresponding to basal impedance (Z0), deviation from basal impedance (\u2212z(t)), and ICG (\u2212dZ\/dt)with the sensitivities of 40 mV\/\u03a9,0.5V\/\u03a9,and400mV\/(\u03a9\u22c5s\u22121),respectively. It also provided analog ECG signal as sensed using the voltage elec trodes. The output signals from the ICG instrument were ac quired using the eight-channel, 12-bit signal acquisition mod ule BKUSB-3102^ from Keithley Instruments (Cleveland,Ohio, USA)andconnectedthroughUSBtoabattery-powered notebook PC. The sampling frequency was set at 500 Hz. The echocardiography recordings were carried out using BiE33 echocardiography system^ from Philips Ultrasound (Bothell, WA, USA) with a 5-MHzphased-arrayprobe placed on the chest after applying an ultrasound gel for good contact with the skin. The aortic blood velocity profile was recorded using apical five-chamber view of the ascending aorta. The aortic diameter was measured using parasternal long-axis view at the level of aortic annulus during mid-systole. The velocity-time integral (VTI) was estimated as the areabetween the envelope of the Doppler spectrum and its baseline with the help of the built-in software of the echocardiography machine by tracing the spectral envelope with its track ball. The ECG was recorded using the three-electrode ECG recorder of the echocardiography machine and displayed along with the Doppler echocardiogram. The ECG electrode positions are shown in figure, along with the ICG electrodes. As the record ings of ICG and Doppler echocardiogram waveforms employed independent time bases, the cardiac cycles of the two recordings were synchronized by alignment of the corre sponding ECG-Rpeaks. For a subject with normal health, two recordings were car ried out. The first recording was carried out with the subject relaxed, rested, and lying in the left-lateral position with a slight folding of the right leg. For the second recording, the subject underwent an exercise to increase the heart rate. The exercise was carried out, following the first four stages of the Bruce exercise protocol, for about 10 min on the \"GE T-2100\" treadmill from GE Healthcare (Wauwatosa, WI, USA) attached with \"Smart Biphasic\" defibrillator from Philips Healthcare (Andover, MA, USA). The signals were recorded soon after cessation of the exercise and with the subject lying the same way as for the first recording. The first and second sets of recordings are referred to as \"under-rest\" and \"post-exercise\" recordings. For a subject with cardiovas cular disorder, only the under-rest recording was carried out. For all recordings, the subjects were advised to avoid any movements in order to minimize the motion artifacts, but no restrictions were placed on breathing. The recordings have been organised as a database and will be available for ICG related research. The under-rest (UR) and post-exercise (PE) recordings from the 18 subjects with normal health (SNH) have 630 and 625 cardiac cycles, respectively, and these are referred to as the SNH-UR and SNH-PE recordings. These cycles pooled together resulted in 1255 cardiac cycles and are referred to as SNH-UR+PE. The under-rest recordings from the 22 subjects with cardiovascular disorders (SCD) have 842 cardiac cycles and these are referred to as the SCD-UR recordings. "