Effects of Injection Site on the Accuracy of Thermal Washout: Methods and Materials (2)
Analogue of the Cardiac Ventricle
Basic Structure of the Model Heart: A model heart with end-diastolic volume of 150 ml was constructed, the bottom of which was made of a movable rubber board connected to a piston and an electric motor, and the top of which was equipped with two oneway valves (Fig 1). Each valve was connected to the inflow (venous) or outflow (arterial) circuits, which in turn were connected to a large-volume constant-temperature (37°C) reservoir. Warm water from this reservoir filled the chamber and circuits and was circulated by strokes of the artificial heart. buy ventolin inhalers
Valvular Structure and Flow Characteristics: One end of a hollow cylinder (internal diameter, 25 mm; height, 35 mm) was covered with a board having a center hole (12-mm in diameter), and the other end with a porous board (six 6.5-mm-diameter circles set in a circle). In this cylinder, a ball (diameter, 22 mm) made of hard nylon occluded the 12-mm hole by compression by a supporting wire spring of pyramid shape (the lower end of the spring [diameter, 6 mm] was secured to the porous end of the cylinder; the upper end was 19 mm in diameter). The spring constant of this spring was 0.025 kg/mm and sufficient to respond to the pressure change generated by the piston movement and to prevent regurgitation. A pair of valves was set at the top of the chamber in opposite directions to each other; one was connected to the inflow (venous) circuit and the other to the outflow (arterial) circuit, and thereby flow was permitted in only one direction, from venous to arterial side. When a bolus of blue dye was injected in the inflow tract, it flowed turbulently into the chamber with movement of the piston, mixed completely and instantaneously in the chamber, and no regurgitation was noted.
Figure 1. Outline of model circuit.