Page 104 - Clinical Pearls in Cardiology

92 Clinical Pearls in Cardiology

heart or in the large arteries. It is usually caused by one
of the following mechanisms:
1. Increased velocity of blood flow through normal
valves or blood vessels.
2. Normal forward flow though narrowed or deformed
valves or blood vessels.
3. Backward or regurgitant flow through incompetent
valve.
4. Vibration of loose structures within the heart.
A systolic murmur is a murmur that begins with or
after the first heart sound and ends before or with the
second heart sound. A diastolic murmur is a murmur
that begins with or after the second heart sound and
ends with or before the first heart sound. Continuous
murmurs begin in early systole and continue through
the second heart sound into all or part of diastole.
12. What are functional murmurs?
Functional murmurs are produced by the turbulence of
blood flow in the absence of structural abnormalities of
the heart or blood vessels. They are mainly of two types:
1. Innocent functional murmur: It is due to the
disturbance in blood flow generated by a heart with
normal cardiac output (e.g. the Still’s murmur in
children, the pulmonary ejection murmur in thin
adolescents).
2. Physiologic functional murmur: It is due to the
disturbance in blood flow generated by a heart with
increased cardiac output (e.g: the continuous venous
hum, which is best heard just above the clavicle on
the right side of the neck, the midsystolic flow
murmurs in high output states like anemia,
pregnancy, vigorous exercise, fever, etc.)