What is meaning of Gallop in Atrial Gallop rhythm

What is meaning of Gallop in Atrial Gallop rhythm & Ventricular Gallop rhythm ?

Gallop rhythm is abnormal heart auscultation , gallop , presence of S1 and S2 and either of s3 and s4 with increased heart rate produce a characteristic gallop sound. S3 is ventricular and s4 is atrial

Gallop is a term given for some kind of hemodynamic abnormality during rapid ventricular filling. That means it’s a phenomena of diastole. Out of all phases of V. Diastole there are only 2 phases when rapid ventricular filling happen :

  1. During rapid V. Filling in early diastole : if rate of V. Filling increases relatively more than normal in this phase then it’s called Ventricular gallop(called S3)

  2. when atria contract at end of diastole(just before start of systole) : if rate of V. Filling increases relatively during this phase then it’s called Atrial Gallop(S4) .

S3 gallop is found when There’s already overloaded ventricles during early diastole and still there’s rapid filling . Ex : in Heart failure , high cardiac output states like in pregnancy . Here ventricles are compliant so can stretch to accommodate excess coming blood

S4 gallop is found when atria has to push blood forcefully into a non compliant ventricule ( this ventricle is non compliant because of something which is creating a hindrance during ventricular systole) . Ex : in High systemic Hypertension , AS .