Cardiac Cycle: Heart Murmurs

Mary Beth Fontana MD

Block Objectives• Describe the mechanisms of production of cardiac

murmurs and vascular bruits • Describe how cardiac murmurs are characterized; relate

to the cardiac cycle and cardiothoracic relationships • Distinguish between normal and abnormal heart sounds

and murmurs•  Describe how respiratory and positional maneuvers can

enhance cardiac diagnosis

 

Objectives- murmurs

• Describe systolic, diastolic, and continuous murmurs and give etiologies

Resources• Lilly 5th edition;

– Chapter 2 pp. 36-43– Blaufuss.org:Heart Sound Tutorial & Quiz

• CSEAC: Interactive Cardiac Exam & Physiologic Origins of Heart Sounds and Murmurs (CD used in lecture)

CSEAC Access

• Fill out a reservation form at the link:• http://medicine.osu.edu/orgs/clinicalskills/p

rocedural request form/pages/index.aspx

• In the Clinical Skills Center’s 6th floor small group debriefing rooms

• After completing the form, will be contacted in 2-3 days to schedule time

• Plan ahead

Heart murmurs

• Audible prolonged sounds generated by turbulent blood flow

Laminar and Turbulent Flow

Flow

Pressure

Laminar flow Turbulent flow

Re = Vdp/

V – mean velocity; d – diameter;p – fluid density; - fluid viscosity

Reynold’s number

Re > 2,000

Laminar (streamline) flow =different layers of molecules move parallel to each other

(for homogeneous fluids)

Changes in velocity of flow or diameter of a vessel or valve are the usual causes of murmurs and bruits

Mechanisms of Murmurs

#1 Flow across partial obstruction#2 Increased flow across normal structures#3 Ejection into a dilated vessel#4 Regurgitant flow across incompetent valve#5 Abnormal communication between high and low pressure chambers or vessels

#1 Flow Across Partial Obstruction

• Heart valve that doesn’t open completely when it should – called stenosis

• Narrowing of outflow from the heart by excessive muscle in a ventricle

• Localized narrowing of a blood vessel– aorta, pulmonary artery, peripheral vessel

• A murmur over a peripheral vessel is called a BRUIT

#2 Increased Flow Across Normal Structures

• Increased stroke volume and/or rapidity of ejection of blood by the ventricles

• Many causes are physiologic– Children– Slow heart rates– Exercise– Pregnancy

• Pathologic– anemia, Congenital heart disease – atrial septal defect

#3 Ejection Into Dilated Vessel

• Least common cause• Dilation of the proximal aorta or pulmonary

artery from whatever cause

#4 Abnormal Flow When a Valve Doesn’t Close

• Aortic & pulmonic valves should be closed during diastole

• Mitral and tricuspid valves should be closed during systole

• Turbulent flow from the leaking valve is driven by higher pressure on one side of the valve

Normal Cardiac Cycle

• RA (2-8)• RV 30/2-8• PA 30/12• LA (2-12)• LV 140/2-12• AO 140/90

#5 Abnormal Communication Between High and Low Pressure Chambers or Vessels

• Result of a congenital defect– Between ventricles– ventricular septal defect– Between aorta and pulmonary artery- patent

ductus arteriosus

Normal Cardiac Cycle

• RA (2-8)• RV 30/2-8• PA 30/12• LA (2-12)• LV 140/2-12• AO 140/90

Description of Murmurs

• Timing – systolic, diastolic, continuous• Intensity – Grade I-VI systolic

Grade I-IV diastolic• Pitch or frequency – high if large pressure

difference between chambers or vessels, low if small pressure difference

• Shape or configuration – crecendo-decrescendo or decrescendo

Description of Murmurs

• Location – maximum intensity closest to source – use anatomic landmarks

• Quality – harsh, blowing, musical• Radiation – in direction of turbulent blood

flow• Response to maneuvers – position

change, respiration

Normal Cardiac Cycle

• RA (2-8)• RV 30/2-8• PA 30/12• LA (2-12)• LV 140/2-12• AO 140/90

Systolic Murmurs

Systolic Ejection Murmur• Pathologic - #1 partial obstruction to flow – aortic or pulmonic

stenosis• Crescendo- decrescendo- which parallels the increased flow

during early ventricular ejection with decreased pressure and flow later in systole.

• Always a gap between S1 and beginning of murmur(isovolumic contraction time) and the murmur ends before respective second sound(A2 or P2)

• Grade III/VI or greater in intensity• Many frequencies, often harsh, so heard with the diaphragm and

bell• Best heard 2 RSB for AS; 2LSB for PS• AS radiates to the carotids

Systolic Ejection Murmur

• Physiologic--#2 increased flow across normal structures

• called “innocent” or “functional”• Usually grade I-II/VI in intensity• Best heard in the aortic or pulmonary area• Decrease in intensity in upright position•  

Systolic Ejection Murmur

S1 S2

Parallels rapid early ventricular ejection and reduction of flow later in systole

Pansystolic Murmur

Pansystolic murmur

S1 S2

Large pressure difference between chambers throughout systole

Start with S1 and continue to S2

Late Systolic Murmur

• #4 Abnormal Flow When a Valve Doesn’t Close • Systolic prolapse of mitral leaflet(s)• maximum prolapse occurs in mid-late systole with

mild prolapse, so regurgitation occurs late.• Often preceded by one or more nonejection clicks

•

Late Systolic Murmur

S1 S2

With mild mitral leaflet prolapse the valve doesn’t leak until late systole

Diastolic Murmurs

Diastolic Decrescendo Murmur• #4 Abnormal Flow When a Valve Doesn’t Close• aortic regurgitation, pulmonic regurgitation with severe

pulmonary hypertension• high pitched due to large vessel – ventricular pressure

difference during diastole• decrescendo because the pressure difference

gradually decreases• begin with the S2 component (A2 or P2)• both best heard at left sternal border with the

diaphragm

Diastolic Decrescendo Murmur

S1 S2

Aortic regurgitation – the murmur starts with A2. Intensity drops as aorta-LV pressure difference decreases during diastole

Mid-Late Diastolic Murmur• #1 Flow across partial obstruction – mitral, tricuspid

stenosis• Gap from S2 to murmur beginning due to isovolumic

relaxation; opening snap of AV valve initiates murmur• Presystolic accentuation when atrial contraction

increases the velocity of flow across the valve• low pitched due to small pressure difference between

atrium and ventricle. Often called “rumbles”• Best heard with the bell at apex in the left lateral

position for mitral stenosis; LLSB for tricuspid stenosis

Mid-Late Diastolic Murmur

S2

OS

S1

Mitral stenosis – murmur begins with mitral valve opening and accentuates with atrial contraction

P wave indicates sinus rhythm

Middiastolic Low Pitched Murmur• #4 pulmonic valvular regurgitation with normal

pulmonary artery pressure; best heard at LSB with the bell

• #2 high early diastolic flow across mitral or tricuspid valves as in severe mitral, tricuspid regurgitation; best heard at apex for mitral, LLSB for tricuspid with the bell

• #1 preclosure of mitral leaflets by severe aortic regurgitation (Austin Flint)

Middiastolic Murmur

S1S2

If severe mitral, tricuspid regurgitation, early diastolic flow into the ventricle is markedly increased

Continuous Murmur• #5 Any communication between high pressure and lower

pressure where the pressure difference persists from systole into diastole. Blood flow always in one direction

• Patent Ductus Arteriosus between aorta and pulmonary artery

• Continuous does not necessarily mean that murmur never stops; only that it starts in systole and spills over S2 well into diastole, usually peaking around S2.

• Usually multifrequency so can be heard with diaphragm or bell. PDA murmur can be quite loud and has been called a “machinery” murmur. Heard best at the upper left sternal border

Continuous Murmur

S2S1 S2

Any communication between systemic and pulmonary circulations- large pressure difference throughout cardiac cycle – turbulent flow always in one direction as in patent ductus arteriosus

Continuous Murmur

S1 S2

If downstream pressure is elevated, the later diastolic component may not be audible as in pulmonary hypertension with a PDA

To and Fro Murmurs

To and Fro Murmurs

• #1, #4 any combination of stenosis and regurgitation at any cardiac valve.

• there is a gap between the systolic (to) and diastolic (fro)murmurs since blood flow has to change direction

• murmurs tend to have different pitch, configuration, and quality

To and Fro Murmurs

S1 S2

Stenosis and regurgitation of a cardiac valve – blood flow has to change direction

This example is aortic stenosis and regurgitation

Thrills & Bruits

• Thrill – palpable vibration felt where a murmur is loudest and of Grade IV or more intensity

• Bruit - an audible “murmur” over a peripheral vessel

Maneuvers• Respiratory variation – right sided murmurs

increase with inspiration• Postural change – standing and squatting

change ventricular volume• Leg raising – increases right heart murmurs

immediately• Isometric handgrip – raises arterial pressure• Variation in R-R interval- ejection murmurs

accentuate after long R-R interval, regurgitant murmurs do not

Summary

• Describe all characteristics of a murmur• Judge the significance of a murmur by the

rest of the history and physical findings• Systolic murmurs can be benign or

pathologic; diastolic pathologic• The H & P makes most cardiac diagnoses