Describe Pharmacologic Agents in amyl nitrite ?
Amyl Nitrite : It produces vasodilatation which initially results in marked fall in BP and in the next 30-60 seconds there is reflex tachycardia followed by an increase in cardiac output.
An ampoule of amyl nitrite is taken in gauze and crushed near the supine patient's nose and the patient is asked to inhale over 10-15 seconds.
Major auscultatory changes occur in the 1st 30 seconds after inhalation:
S1 is augmented, A, is diminished, and pathological S, is augmented.
A,-OS interval shortens.
Murmur of MR, VSD and AR are reduced.
Systolic murmurs AS, PS, HOCM and TR are accentuated.
Diastolic murmurs of MS, TS and PR are accentuated.
PDA murmurs and of AV fistula are reduced.
TOF - right to left shunt increases due to fall in systemic BP, therefore blood flow from RV to PA is reduced.
Systolic click and systolic murmur of MVP occur earlier.
If amyl nitrite is not available, the test can be done using isosorbide dinitratc.