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Electrophysiology
Published in A. Bakiya, K. Kamalanand, R. L. J. De Britto, Mechano-Electric Correlations in the Human Physiological System, 2021
A. Bakiya, K. Kamalanand, R. L. J. De Britto
The cardiopulmonary system consists of blood vessels that carry nutrients and oxygen to the tissues and removes carbon dioxide from the tissues in the human body (Humphrey & McCulloch, 2003; Alberts et al., 1994). Blood is transported from the heart through the arteries and the veins transport blood back to the heart. The heart consists of two chambers on the top (right ventricle and left ventricle) and two chambers on the bottom (right atrium and left atrium). The atrioventricular valves separates the atria from the ventricles. Tricuspid valve separates the right atrium from the right ventricle, mitral valve separates the left atrium from the left ventricle, pulmonary valve situates between right ventricle and pulmonary artery, which carries blood to the lung and aortic valve situated between the left ventricle and the aorta which carries blood to the body (Bronzino, 2000). Figure 3.9 shows the schematic diagram of heart circulation and there are two components of blood circulation in the system, namely, pulmonary and systemic circulation (Humphrey, 2002; Opie, 1998; Milnor, 1990). In pulmonary circulation, pulmonary artery transports blood from heart to the lungs. The blood picks up oxygen and releases carbon dioxide at the lungs. The blood returns to the heart through the pulmonary vein. In the systemic circulation, aorta carries oxygenated blood from the heart to the other parts of the body through capillaries. The vena cava transports deoxygenated blood from other parts of the body to the heart.
Mechanobiology of Heart Valves
Published in Jiro Nagatomi, Eno Essien Ebong, Mechanobiology Handbook, 2018
Joshua D. Hutcheson, Michael P. Nilo, W. David Merryman
The valves that direct blood flow from the heart to the body and lungs are known as semilunar valves due to the crescent shape of the leaflets (Figure 10.3a, a view of the aortic valve from the perspective of the aorta). The pulmonary valve is situated between the right ventricle and pulmonary artery, and the aortic valve directs flow from the left ventricle to the aorta. These two valves differ from the atrioventricular valves in that they lack chordae tendineae and rely solely on the hemodynamic forces of blood flow to direct opening and closing of their leaflets. Ventricular contraction during systole forces the leaflets of the semilunar valves open. During diastole, the leaflets coapt to prevent blood from flowing back into the ventricles. As we will discuss in much greater detail, the pressure of the blood on the leaflets of the closed semilunar valves during diastole introduces a high amount of stress on the tissues. This stress can lead to mechano-dependent signal transduction of pathologic responses at the cellular level within the leaflets that can greatly alter valve function.
Cardiovascular System:
Published in Michel R. Labrosse, Cardiovascular Mechanics, 2018
The aortic and pulmonary valves are found at the base of the heart, where the blood vessels attach. The pulmonary valve separates the right ventricle from the pulmonary artery, while the aortic valve separates the left ventricle from the aorta. During the diastole, the pressure in the blood vessels is higher than in the relaxed ventricles, and the back pressure shuts these valves. With systolic contraction, the pressure in the ventricles will rise. Once it exceeds the vessel pressure, it will push the aortic and pulmonary valves open, allowing for forward ejection of the blood. As diastole returns and the ventricle pressure once again drops below the vessel pressure, these valves will close due to the pressure differential. It is the closing of the valves that can be heard with a stethoscope. The first heart sound, “lub,” is the closing of the A-V valves, while the second heart sound, “dup,” is associated with the closure of the aortic and pulmonary valves.
Development of a miniature and ASIC based impedance cardiograph
Published in Journal of Medical Engineering & Technology, 2020
Jyoti V. Jethe, T. S. Ananthakrishnan, G. D. Jindal
The technique got an impetus for cardiological applications from Kubicek et al in 1966 [2], who introduced first time derivative of the impedance (dZ/dt) for simplistic assessment of blood ejected by left ventricle into aorta during one heartbeat, commonly known as stroke volume (SV). Multiplication of SV by heart rate yielded the total output of heart during one minute, commonly known as cardiac output (CO). For beat to beat continuous cardiac output monitoring, SV is multiplied by instantaneous heart rate. Figure 1 shows commonly used electrode configuration (Kubicek’s neck-abdomen configuration) and a typical dZ/dt waveform recorded. Characteristic points on the waveform (A, B, C, X, Y, O and Z) represent important cardiac events such as end of atrial contraction, opening of aortic valve, instant of maximum aortic flow, aortic valve closing, pulmonary valve closing, mitral valve opening and end of rapid filling phase [3,4,5] respectively; of which complex BCX corresponds to ventricular systole. This close correlation has evolved Impedance Cardiography (ICG) as a non-invasive method for monitoring cardiac function and other parameters of the cardiovascular system [6,7,8].
Left ventricle hemodynamics induced by a new anatomical-shaped mitral valve
Published in Computer Methods in Biomechanics and Biomedical Engineering, 2019
The double-activation simulator mimics the left human heart from the pulmonary valve to the systemic capillaries, going through the left atrium (LA), the left ventricle (LV) and the aorta (AO) (Tanné et al. 2010). The left atrium and ventricle were anatomical shape silicone molding parts. They were both immersed into separate and closed boxes filled, and activated by two Vivitro super pumps (VivitroLabs, Victoria, BC, Canada). Pulmonary venous return was done by a gear pump. The fluid circulating was a water and glycerol solution (40% of glycerol, 60% of water) with a dynamic viscosity of 3.8 ± 0.2 cP. LV, LA and AO pressures were measured using 3 pressure catheters (Millar MPR 500 [Millar Sensor System Solution, Houston, Tex]). The diastolic and systolic flow volumes were measured using an electromagnetic flowmeter (Probe 95 [Carolina Medical, East Bend, NC]) positioned between LA and LV, 5 mm upstream of the mitral valve. The effective orifice area (EOA) was calculated by dividing the diastolic flow volume measured with the flowmeter by the time velocity integral of the mitral flow.
Structure and motion design of a mock circulatory test rig
Published in Journal of Medical Engineering & Technology, 2018
Yuhui Shi, Theodosios Korakianitis, Zhongjian Li, Yubing Shi
Parts DKG and E combined to represent the blood flow in the left and right atriums, the aorta and the pulmonary artery. Two heart valves are equipped on the silicon septum DKG, and they are functioned as the mitral valve and the tricuspid valve in the heart. The two valves and the septum are attached to and driven by the motion control mechanism which moves in the vertical direction, thus to simulate the bulging of the septum in the heart in the diastolic phase. Two vertical channels in part E represent the roots of the aorta and the pulmonary artery. Two more heart valves are installed near the inlet to the aorta and the pulmonary artery to simulate the aortic valve and the pulmonary valve.