Analog simulation of two clinical conditions: (1) Acute left ventricle failure; (2) exercise in patient with aortic stenosis

Analog Simulation of Aortic Stenosis

“…Input to the left ventricle is slightly modified as published (Dolenšek et al, 2009). Contractility modulation is the same as described in Sever and coworkers (Sever et al, 2007); via negative feedback it can be increased from 1 to about 8 "units of contractility". The time constant for myocardial contractility modulation control is increased from 1 s to 5 s. Aortic stenosis is simulated as described (Sever et al, 2007).…”

“…As in previous simulations four targets are modulated by negative feedback: venous tone, contractility of right ventricle, contractility of left ventricle, and heart rate. Essentially, the present equivalent circuit is the same as reported (Sever et al, 2007). The resetting of mean arterial pressure includes procedures whereby its resting value, "clamped" at about 98 mm Hg is shifted and then "clamped" again at a higher level.…”

“…Contractility modulation is the same as described in Sever and coworkers (Sever et al, 2007); via negative feedback it can be increased from 1 to about 8 "units of contractility". The time constant for myocardial contractility modulation control is increased from 1 s to 5 s. Aortic stenosis is simulated as described (Sever et al, 2007). Exercise is simulated by decreasing arteriolar and capillary resistance by 50 % and by resetting mean arterial pressure.…”

“…The resetting of mean arterial pressure includes procedures whereby its resting value, "clamped" at about 98 mm Hg is shifted and then "clamped" again at a higher level. Heart rate control is the same as described in Sever and coworkers (Sever et al, 2007); the duration of the systole is constant, www.intechopen.com 200 ms in all simulation conditions. Mitral and aortic valve are simulated by diode D1.…”

“…Third, the mean arterial pressure wasin some conditions -reset from the normal to a higher operating level (simulating increased sympathetic tone). By using these approaches recently various clinical conditions were simulated: acute left ventricle failure (myocardial infarction), aortic stenosis and exercise in man with aortic stenosis (Sever et al, 2007), and consequences of aortic and of mitral regurgitation (Dolenšek et al, 2009). In present simulations it is attempted to extend both recent simulations quoted above.…”