• Key to the auscultation of the heart- Leatham.

    Causation

  • Frequency- 120 to 150 Hz.
  • Occurs in downstroke of carotid pulse.
  • Coincides with incisura of great artery pulse.
  • Occurs due to sudden deceleration of retrograde blood flow in the great arteries at the end of systole setting the cardiohemic system into vibration.
  • Hangout interval is the distance in x-axis (time) between ventricular pressure and great artery pressure at the time of the incisura.
  • Hangout interval is more for pulmonary artery when compared to aortic.
  • Mechanisms of splitting of S2
    • Later P2 – due to increased pulmonary hangout interval and increased RV ejection time
    • Earlier A2

    Abnormalities of intensity

  • Increased intensity of A2
    • Increased pressure- Systemic hypertension, coarctation of aorta.
    • Increased flow
    • Root dilation- ascending aortic aneurysm
    • Anterior displacement of aorta- TOF, TGA
  • Decreased intensity of A2-
    • AR
    • Valvular AS
  • Increased intensity of P2- P2 is loud if it is louder than A2 at the pulmonary area (some are of the opinion that same intensity as A2 also indicates loud P2) or if it is audible at the apex
    • ASD
    • Pulmonary hypertension
  • Soft P2-
    • Valvular PS
    • Masking of P2 by loud A2- TOF, TGA

    Splitting

  • At least 30 msec interval is needed to appreciate splitting.
  • Enhanced on upright position as RV systole shortens more than LV systole.
  • Wide splitting-
    • means expiratory split present.
    • Confirm is upright position.
    • Persists after ASD repair due to persistently increased pulmonary artery compliance.
    • In ASD, both A2 and P2 are delayed.
    • Causes of increased pulmonary hangout interval are ASD, PS and IDPA.
    • Causes of wide splitting-
      • Delayed P2-
        • Hemodynamic-
          • PS (A2-P2 delay of more than 100 msec indicates PS gradient of 100 mmHg if there is no infundibular PS)
          • ASD
          • IDPA
          • RV failure (usually due to PAH or biventricular failure) (mechanisms of RV failure in LV failure are syntitial effect, coronary turgor effect, Bernheim effect and secondary to PAH)
          • Massive pulmonary embolism
        • Electrical-
          • RBBB
          • LV VPCs, LV pacing
          • WPW with LV preexcitation
      • Early A2-
        • MR
        • VSD
        • Pericardial tamponade- reduction in LV stroke volume is greater than that in RV stroke volume as the latter is relatively fixed
        • Constrictive pericarditis
        • LA myxoma
      • Other causes
        • Pectus excavatum and straight back syndrome
        • Some normal children.
  • Fixed splitting-
    • ASD
    • RV failure
    • Acute pulmonary embolism
  • Reversed or paradoxical splitting
    • Means S2 is more fixed in expiration than in inspiration
    • Type I paradoxical splitting-
      • Inspiration- Single S2
      • Expiration- Split S2 (P2-A2)
    • Type II paradoxical splitting-
      • Inspiration – Split S2 (A2-P2)
      • Expiration- Split S2 (P2-A2)
    • Type III paradoxical splitting-
      • Inspiration- Single S2
      • Expiration- Single S2 (P2-A2, but separation is 20 msec or less)
    • Thus in type II, we get split in both phases. In type III, we do not get any split. In type I, split in expiration, no split in inspiration.
    • Causes of reversed splitting-
      • LBBB, RV preexcitation
      • LVOTO and AS- due to delayed LV- aortic pressure crossover
      • Angina
      • Aortic dilation due to AS or AR
      • PDA
  • Pseudo-paradoxical splitting-
    • In COPD, inspiration leads to disappearance of P2 due to lung interposition- mistaken for paradoxical splitting
  • Narrow splitting-
    • Severe PAH without RV failure
  • Single S2-
    • Absent P2-
      • Severe PS
      • Pulmonary atresia
      • Severe TOF
      • Most cases of tricuspid atresia
    • Absent A2-
      • Severe AS
    • Absent A2 and P2-
      • Truncus arteriosus
    • Fusion of A2 with P2-
      • Eisenmenger VSD
      • Single ventricle
    • Apparently absent P2-
      • COPD
      • Obesity
      • Pericardial effusion