There are two types of stethoscopes used - membranous (transmits better high frequency sounds and bell-shaped (for listening to low frequency sounds and murmurs, e.g. the 3^rd sound, 4^th sound, and diastolic mitral and tricuspid murmurs).
 
Normal cardiac sounds:
 
example a); example b)
 
Auscultation is of great significance - the most important physical examination of the heart (see the picture Auscultation points on the chest, sounds).
 
I^st sound
 
This is produced by closing of the mitral and then tricuspid valves at the beginning of ventricular systole.
 
II^nd sound
 
This is produced by closure of the semilunar valves, firstly the aortic and secondly the pulmonary (changes with respiration). In expiration, both components are getting closer together; in inspiration they are moving away - the physiological segregation of the 2^nd sound. It is due to the fact, that in inspiration, the negative intrathoracic pressure is intensified, the return to the right heart increases and the increased stroke volume of the right ventricle prolongs its ejection and therefore leads to a delayed closure of the pulmonary valve - e.g. in BRTN (block of the right Tawara´s node) in ECG, in atrioseptal defect etc.
 
NOTE - in pathological conditions, the paradox split of the 2^nd sound occurs if the left ventricle is overloaded and its systole is prolonged (e.g. aortic stenosis, ischaemic heart disease, BLTN - block of the left Tawara´s node in ECG) - closure of the aortic valve is delayed, firstly the pulmonary, then the aortic component. Therefore, in inspiration the 2^nd sound is paradoxically split, in inspiration the two components are moving away (i.e. the aortic component and the pulmonary one physiologically), so that they merge.
 
III^rd sound
 
It is audible in patient lying on the left side, at the apex, with the bell-shaped stethoscope.
 
It is produced by vibrations of the ventricular myocardium in the phase of rapid filling of the ventricles at the beginning of diastole; it is always produced, but as it is of low frequency character, it is audible:
 

	In young patients in physiological conditions or
	In elderly patients in pathological conditions it corresponds with low frequency -protodiastolic gallop (in failing heart).

 
IV^th sound
 
It is audible in the patient lying on the left side, at the apex, with the bell-shaped stethoscope.
 
It is elicited by vibrations of the ventricular myocardium on ejection of the blood into the ventricle during the ventricular systole at the end of diastole; but it is absent in atrial fibrillation!!!
 
It is found in young healthy people or in elderly patients as the presystolic gallop.
 
Concurrence of the 3^rd and 4^th sounds in cardiac insufficiency is called the summation gallop.
 
NOTE! IT IS ALWAYS AN IMPORTANT SIGN OF THE LEFT VENTRICULAR FAILURE!
 
Most frequent arrhythmia - - atrial fibrillation
 
Systolic clicks are accessory sounds produced during the systolic phase by the valvular activity.
 

	Ejection aortic click corresponds probably with sudden distension of the aortic valve. It occurs in early systole and is of a sharp clicking character. It is best audible in the apex region in dilatation of the aortic root, regardless of the cause of dilatation.
	Systolic click may occur also during the midsystole or late systole, it sounds like a short, dry whip crack and can be multiple. It is caused by an abnormal function of the mitral valve and it is considered a sign of mitral valve prolapse.

 
Ejection aortic and systolic clicks are often confused. Systolic click occurs later during the systole and in inspiration approaches the 1^st sound.
 
Murmurs
 
Murmur - an acoustic phenomenon produced by vibrations of the valvular apparatus or another structure, if the laminar blood flow is replaced by turbulent circulation.
 
Classification of the murmurs based on localisation in the cardiac cycle:
 

	Systolic can be functional (e.g. in childhood, in anaemia, in hyperkinetic circulation, neurasthenia, thyreopathy, febrile conditions, stress) or of organic aetiology. Murmurs are further classified according to a more precise time specification into:    early systolic (protosystolic)    midsystolic (mesosystolic)    late systolic (telesystolic)    lasting the whole systole (holosystolic).
	Diastolic murmurs are always of organic aetiology (i.e. pathological!); they are classified into:    early diastolic (protodiastolic)    late diastolic (presystolic)    holodiastolic.

 
Based on the character given by the prevailing frequency of vibrations, the murmurs are classified into:
 

	Harsh (rough)
	Bellows (blowing)
	Machinery
	Musical (high-pitched character)
	Continuous
	Crescendo
	Decrescendo
	Crescendo - decrescendo.

 
According to the intensity 6 murmur grades can be recognised:
 

	1st grade - hardly audible murmurs
	2nd grade - murmurs soft, but audible
	3rd grade - murmurs of middle audibility
	4th grade - loud murmurs
	5th grade - very loud murmurs, audible upon minimum contact of the stethoscope with the thoracic wall
	6th grade - distant murmurs, i.e. audible without placing the stethoscope on the chest.

 
4^th to 6^th grade murmurs are usually connected with the palpable whirl. The 2/6 murmurs indicate the 2^nd grade intensity out of the given six grades.
 
Loudness of the murmur is usually proportional to the velocity of blood stream between the two cavities. Velocity of the blood movement depends on the pressure gradient over the ostium, on the shape of the ostium and size of the minute volume. In general, loud murmurs occur in a higher gradient, smaller ostium, or greater minute volume - e.g. a small ventricular septal defect elicits a very loud systolic murmur (great pressure gradient over the defect).
 
Auxiliary manoeuvres to improve murmur audibility:
 

	In exertion, murmurs are intensified, but in heart failure they remain unchanged.
	Diastolic murmur in mitral stenosis is better audible in the position on the left side and following exercise.
	Diastolic murmur in aortic regurgitation is examined in the sitting patient, slightly bent forwards.
	Murmurs from the right heart are intensified in inspiration and they get reduced in Valsalva manoeuvre.
	Left heart murmurs are accentuated in expiration.

 
Accentuation of the sounds:
 

	Accentuation of the 2nd sound over the aorta is a manifestation of hypertension in the systemic circulation.
	Accentuation of the 2nd sound over the pulmonary artery is a manifestation of hypertension in the pulmonary circulation