3.3 CS: Heart Auscultation

HEART AUSCULTATION

• Listening to the heart sounds with the aid of the use of stethoscope

• Heart sounds are caused by closing of the different heart valves

POINT OF MAXIMUM INTENSITY (PMI) /PUNCTA MAXIMA

It is a spot on the thoracic wall where a valve sound is the loudest

Ventricular contraction (systole)

an increase in ventricular pressure and close of the atrioventricular valves (1st heart sound) and opening of the semilunar valve (aortic and pulmonic valves)

Ventricular relaxation (diastole)

atrioventricular valves opens and the semilunar valves closes (2nd heart sound)due to back pressure in the aorta and pulmonary trunk

Systole

contraction of ventricles; occurs between the 1st and 2nd heart sounds

Diastole

relaxation of ventricles; occurs between the 2nd and 1st sounds

1st heart sound (“lub”)

caused by closure of AV valves at onset of systole

2ndheart sound (“dub”)

caused by closure of semilunar valves at the end of systole

Heart Murmurs

abnormal sounds caused by blood flow turbulence; it can either be due to valvular or non-valvular problems

Systolic murmur

occurs between the 1st and 2nd heart sounds; when the AV valves should be fully closed and the semilunar valves opens

Diastolic murmur

occurs between the 2nd and 1st heart sound when the semilunar valves is fully closed and the AV valves opens

Aortic stenosis

narrowing of the aortic valve; it impedes the normal left ventricular emptying.

Subaortic stenosis

• most common form

• Breed predisposed is Boxers, Golden Retrievers, Rotweillers, and German Shepherd

Pulmonic stenosis

refers to narrowing of the valve between the right ventricle (a chamber of the heart) and the pulmonic artery (the major blood vessel that carries blood from the heart to the lungs).

Valvular form

most common; breed predilections such as English bulldogs, boxers, beagles, and Boykin Spaniels

Supravalvular form

uncommon and most often seen in Giant Schnauzers

Mitral valve stenosis

• narrowing of the mitral valve opening caused by the abnormalities of the mitral valve

• Rare in dogs and cats and it can occur together with other congenital defects such as subaortic stenosis, mitral valve dysplasia, and pulmonic stenosis

Mitral valve dysplasia

leads into a mitral insufficiency and systolic regurgitation of the blood into the left atrium; Canine breeds predisposed includes Bull terriers, German Shepherds, and Great Danes

Tricuspid valve dysplasia

leads into the tricuspid insufficiency and systolic regurgitation of blood into the right atrium; Breeds predisposed are Labrador Retrievers and German Shepherds

Atrial septal defect

It results when the foramen ovale and second foramen ovale overlaps; allowing blood to flow from left to right, leading into a poor oxygenation of the blood which can leads to cyanosis

Interventricular septal defect

• Failure of the interventricular septum to close, involving the membranous part of the septum

• The most common cardiac anomaly in large animals, it causes systolic murmur

Tetralogy of Fallot

most common defect that produces cyanosis

Pulmonic stenosis

Right ventricular hypertrophy

Ventricular septal defect

Overriding (dextropositioning) of aorta

what comprises the defect tetralogy of fallot (4)