Table 1.

Comparison of elements of Windkessel model in systemic and pulmonary circulation

Characteristic (Ref. No.)	Pulmonary Circulation		Systemic Circulation
	Normal	Pulmonary Hypertension	Normal	Systemic Hypertension
Location of vascular compliance (21)	20% compliance in main, left and right pulmonary arteries; 80% located beyond first branches	20% compliance in main, left and right pulmonary arteries; 80% located beyond first branches	80% of compliance in proximal conduit vessels	80% of compliance in proximal conduit vessels
Pulsatile load, % (19, 21)	25	25	5–10	5–10
Compliance, ml/mm Hg (15, 17, 21)	3.8–12	0.4–3.8	2.5	0.8
Resistance, mm Hg⋅s/ml (21, 60)	0.11	>0.18	1.0	1.2