PMC6661416_01
Intensity of the second heart sound and mean pulmonary arterial pressure during acute vasodilator testing.. The intensity of the second heart sound was measured during heart catheterization at an age of 14 years by acoustic cardiography. The intensity of the second heart sound changed immediately in accordance with changes in pulmonary arterial pressure during 10- to 15-min intervals of acute vasodilator testing with inhaled nitric oxide while breathing air or supplemental oxygen.. L/min: liters per minute, mV: millivolts, ppm: parts per million.
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The response occurs within 30-60 seconds as illustrated in Fig. 1 by the MPAP and abrupt change in the intensity of the second heart sound by acoustic cardiography.
Effect of phosphodiesterase V inhibitors on the pulmonary vasodilatory effect of inhaled nitric oxide.. The patient was monitored in the intensive care unit following heart catheterization at an age of 10 years. Pulmonary and systemic arterial pressures were measured continuously and recorded every 5 minutes for the graph. Adult doses of sildenafil (25 mg, 0.5 mg/kg) and tadalafil (5 mg, 0.1 mg/kg) were given while the patient was awake. Inhaled nitric oxide (20 parts per million) was administered for intervals of approximately 10 minutes. The pulmonary vasodilatory effect of inhaled nitric oxide was not appreciably prolonged by oral treatment with sildenafil or tadalafil. Less variability in her baseline pulmonary and systemic arterial pressures occurred while she was sleeping, between time points 8-14 hours.
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Fig. 2 illustrates that sildenafil and tadalafil did not even prolong the pulmonary vasodilatory effect of iNO.
Timeline of acute vasodilator testing with supplemental oxygen and 20 parts per million inhaled nitric oxide and long-term outpatient therapy.. The baseline ratio of pulmonary to systemic vascular resistance increased while being treated with sildenafil (25 mg/day to 75 mg/day, 0.7 mg/kg/day to 1.9 mg/kg/day) and intermittent transdermal nitroglycerin (0.2 mg/hour). A decrease in the baseline ratio of pulmonary to systemic vascular resistance occurred while being treated with amlodipine (5 mg/day to 15 mg/day, 0.11 mg/kg/day to 0.23 mg/kg/day). The ratio of pulmonary vascular resistance to systemic vascular resistance transiently increased at the onset of puberty. The effect of long-term treatment with amlodipine has not decreased the ratio of pulmonary vascular resistance to systemic vascular resistance to a level that can readily be achieved while breathing nitric oxide.
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Fig. 3 illustrates the impact of long-term outpatient therapy on her baseline ratio of pulmonary to systemic vascular resistance (Rp:Rs) over time.