Chapter 23 Normal Heart Sounds

• Closing of heart valves causes audible sounds.
• No sounds are audible when the valves open in normal condtions.

Normal Heart Sounds

• The sound heard through a stethoscope is usually described as "lub, dub".
• The "lub" sound is associated with the closure of the atrioventricular (A-V) valves at the beginning of systole.
• The "dub" sound is associated with the closure of the semilunar valves (aortic and pulmonary) at the end of systole.
• The "lub" sound is called the first heart sound.
• The "dub" sound is called the second heart sound.
• The normal pumping cycle of the heart is considered to start when the A-V valves close at the onset of ventricular systole.

First Heart Sound

• Occurs due to vibration of the taut valves immediately after closure.
• Vibration of the adjacent walls of the heart and major vessels also contribute.
• Contraction of the ventricles causes backflow of blood against the A-V valves (tricuspid and mitral), causing them to close and bulge toward the atria.
• Chordae tendineae stop the back bulging.
• Elastic tautness of the chordae tendineae and valves causes the back-surging blood to bounce forward again into each respective ventricle.
• This mechanism causes blood, ventricular walls, and taut valves to vibrate and causes vibrating turbulence in the blood.
• Vibrations travel through adjacent tissues to the chest wall, where they can be heard as sound using the stethoscope.

Second Heart Sound

• Results from sudden closure of the semilunar valves (aortic and pulmonary) at the end of systole.
• Semilunar valves bulge backward toward the ventricles when they close.
• Elastic stretch recoils the blood back into the arteries.
• Causes a short period of reverberation of blood back and forth between the walls of the arteries and the semilunar valves, as well as between these valves and the ventricular walls.
• Vibrations in the arterial walls are transmitted mainly along the arteries.
• Vessels or ventricles come into contact with a sounding board such as the chest wall, they create sound that can be auscultated.

Duration and Pitch of Heart Sounds

• Individual heart sounds last slightly over 0.10 second.
• First sound lasts about 0.14 second.
• Second sound lasts about 0.11 second.
• Shorter second sound is because semilunar valves are tauter than A-V valves, so they vibrate for a shorter time than A-V valves.
• Audible frequency range (pitch) in the first and second heart sounds begins at about 40 cycles/sec and goes up above 500 cycles/sec.
• Special electronic apparatus can record sounds beyond the audible range (3 to 4 cycles/sec, peaking at about 20 cycles/sec).
• Major portions of the heart sounds can be recorded electronically by phonocardiography.
• Second heart sound normally has a higher frequency than the first heart sound, specifically:
  • semilunar valves are tauter in comparison with the much less taut A-V valves
  • greater elastic coefficient of the taut arterial walls provides the principal vibrating chambers for the second sound
• Clinicians uses the differences to distinguishes special characteristics of the two respective sounds.

Third Heart Sound

• A weak, rumbling sound sometimes heard at the beginning of the middle third of diastole.
• Possibly explained by oscillation of blood back and forth between the walls of the ventricles initiated by inrushing blood from the atria.
• Analogous to running water from a faucet into a paper sack.
• Does not occur until the middle third of diastole because the ventricles lack sufficient fill to create the tension necessary for reverberation.
• Frequency is usually so low it cannot be heard, but it can often be recorded in the phonocardiogram.
• May be normally present in children, adolescents, and young adults.
• Generally indicates systolic heart failure in older adults.

Fourth Heart Sound

• An atrial heart sound can sometimes be recorded in the phonocardiogram.
• Almost never audible with a stethoscope because of its weakness and very low frequency.
• Occurs when the atria contract.
• Presumably caused by the inrush of blood into the ventricles, which initiates vibrations similar to those of the third heart sound.
• Common in people who derive benefit from atrial contraction for ventricular filling as a result of decreased ventricular wall compliance and increased resistance to ventricular filling.
• Often heard in older patients with left ventricular hypertrophy.

Chest Surface Areas for Auscultation

• Listening to body sounds using a stethoscope is called auscultation.
• Auscultation can distinguish the different heart valvular sounds from different areas (aortic, pulmonic, tricuspid, and mitral).
• Cardiologists distinguishes sounds from different valves through elimination and noting loudness in different areas.
• Auscultation areas are not directly over the valves.
• Aortic area is upward along the aorta.
• Pulmonic area is upward along the pulmonary artery.
• Tricuspid area is over the right ventricle.
• Mitral area is over the apex of the left ventricle.

Phonocardiogram

• Amplifies and records heart sounds using a microphone specially designed to detect low-frequency sound.
• Heart sounds appear as waves.
• Can records third and atrial heart sounds.
• Third heart sound can be recorded in only one-third to one-half of people.
• Atrial heart sound can be recorded in perhaps one-fourth of people.

Valvular Lesions: Rheumatic Valvular Lesions

• Rheumatic fever is an autoimmune disease in which heart valves are likely to be damaged or destroyed.
• Usually initiated by a streptococcal toxin.
• The sequence begins with a group A hemolytic streptococci infection.
• Bacteria cause sore throat, scarlet fever, or middle ear infection.
• Streptococci release proteins against which the body produces antibodies.
• Antibodies react with streptococcal protein and other protein tissues, causing immunological damage.
• Reactions persist as long as antibodies persist in blood.
• Rheumatic fever causes damage in susceptible areas such as the heart valves with the degree of damage correlating with the concentration and persistence of the antibodies.
• Large hemorrhagic, fibrinous, bulbous lesions grow along the inflamed edges of the heart valves.
• The Mitral valve is most often seriously damaged, aortic valve is the second most frequently damaged.
• Right heart valves are less severely affected due to low-pressure stresses.
• Lesions of acute rheumatic fever frequently occur on adjacent valve leaflets simultaneously, so the edges of the leaflets become stuck together.
• Lesions become scar tissue, permanently fusing portions of leaflets.
• Free edges of leaflets become solid scarred masses.
• A valve in which the leaflets adhere to one another is said to be stenosed
• When the valve edges are so destroyed, regurgitation occurs when the valve should be closed.
• Stenosis usually occurs with the coexistence of regurgitation.

Aging and Aortic Valve Stenosis

• With aging, aortic valve often thickens, becomes calcified and stiffer, and may partially obstruct outflow from left ventricle.
• Aortic valve stenosis has become the most common heart valve disease.
• Stenosis of a previously normal aortic valve is called senile calcific aortic valve stenosis.
• Characterized by valve calcium deposition and ossification, which lead to narrowing of the aortic valve orifice.
• Compensatory the left ventricle undergoes concentric hypertrophy.
• Heart pumps with greater vigor against obstructed outflow.
• Pressure gradient develops across calcified valve.
• Hypertrophied left ventricle may be ischemic because of impaired microcirculatory perfusion
• Ejection fraction may be normal, but symptoms of heart failure appear during exercise.
• Stenosis worsens, there are reductions in systolic heart function and congestive heart failure appear, with reductions in stroke volume and cardiac output.
• Calcific aortic valve stenosis usually becomes severe enough to draw clinical attention until after age 70.
• Important symptoms are exertion-related angina, reduced exercise tolerance, and congestive heart failure.
• Shortness of breath (dyspnea) is due to increased left ventricular filling pressure or inability to increase cardiac output adequately with exercise.
• Early recognition and management of aortic stenosis are important.
• Untreated symptomatic aortic valve stenosis is progressive and will ultimately be fatal.
• Transcatheter aortic valve replacement technologies has provided new therapeutic opportunities, especially for older patients,

Heart Murmurs Caused by Valvular Lesions

• Abnormal heart sounds known as heart murmurs, occur when abnormalities of the valves are present

Systolic Murmur of Aortic Stenosis

• Blood is ejected from the left ventricle through only a small fibrous opening of the aortic valve.
• Blood pressure in the left ventricle sometimes rises as high as 300 mm Hg while pressure in the aorta is still normal.
• Nozzle effect created during systole, with blood jetting at tremendous velocity through opening causing the aortic walls to vibrate.
• Loud murmur occurs during systole transmitted throughout the superior thoracic aorta and even into the large arteries of the neck.
• Sound is harsh, may be loud enough to be heard several feet away, and cause a detectable vibration.

Diastolic Murmur of Aortic Regurgitation

• No abnormal sound is heard during systole.
• High-pressure aorta with blood flowing backward into the left ventricle during diastole, creating a "blowing" murmur.
• Heard maximally over the left ventricle due to turbulence of blood jetting into diastolic left ventricle.

Systolic Murmur of Mitral Regurgitation

• Blood flowing backwards from the mitral valve into the left atrium during systole.
• High-frequency blowing and swishing sound.
• Transmitted most strongly into the left atrium, but auscultated thorough the chest wall by the left ventricle to the apex of the heart.

Diastolic Murmur of Mitral Stenosis

• Mitral stenosis has issues with blood passing into the left ventricle, because the pressure never rises above 30mmHG, abnormalities heard are low frequency.
• Heard well in the latter two thirds of the diastole, as the left vetrivle has stretched enough to reverberate it will be heard clearly

Phonocardiograms of Valvular Murmurs

• Aortic stenotic lesion causes loudest murmur and mitral stenotic lesions cause weakest.
• Aortic stenosis and mitral regurgitation murmurs during systole.
• Aortic regurgitation and mitral stenosis occur during diastole.

Circulatory Dynamics in Aortic Stenosis and Aortic Regurgitation

• Aortic stenosis has issues with the left ventricle emptying the blood properly, regurgitation causes the blood to flow backwards.
• Net stroke volume output is reduced.
• Left ventricular musculature hypertrophies, and the left ventricular chamber enlarges.
• Hypertrophy will result in a large left ventricle

Compensatory Effects of Heart Conditions

• Increases blood level to mean arterial pressure, results in the heart pumping when more power is required.

Issue With Valve Related Conditions

• Inadequate coronary blood flow, as ventricular tension is high, and coronary flow is greatly reduced.
• This can lead to ischemia of the heart muscle if left unchecked.
• At early stage, there may be adaptions to workload, but there is a risk of long term issues and serious heart diseases arising from not seeking treatment in a timely manner.

Dynamics of Mitral Stenosis and Mitral Regurgitation

• Mitrial stenosis, blood flow is impeded and much of the blood leaks back.
• Reduces movement of blood from the left atrium.

Pulmonary Edema in Mitral Valvular Disease

• Results in blood buildup which elevates left atrial pressure.
• Causes pulmonary edema.
• Enlarged left atrium and atrial fibrillation.
• High lest atrial pressure, results in the heart travelling far resulting in circulatory issues.

Compensation in Early Mitral Valvular Disease

• Blood volume increases from less excretion and helps cardiac activity.
• Therefore the heart is functional, until it cannot take the strain and starts rising again.

Circulatory Dynamics During Exercise in Patients with Valvular Lesions

• Issues with venous return and abnormalities, which can cause severe affects to people even with simple lesions.
• Heart reserve reduces in proportion, and muscles fatigue from blood flow reduction.

Abnormal Circulatory Dynamics in Congenital Heart Defects

• Malformation of heart or blood vessels, creating defects that affect blood flow.
• Three major types that occur:
  • Stenosis- where the blood flow is restricted/channeled down
  • Anomalies- allows blood from to flow from heart or aorta to the lung
  • Shunts- Allows blood to flow from right to left leading to bad lung distribution

Anomalies with flow and issues of heart conditions

• All conditions have the same reactions as aortic flow, however the dynamics are affected
• Coarctation, is a congential heart condition as well resulting in stenonis and low flow of blood.

Patent Ductus Arteriosus- A Left-To-Right Shunt

• During fetal life, the lungs are collapsed, and the elastic compression of the lungs that keeps the alveoli collapsed keeps most of the lung blood vessels collapsed as well.
• Resistance to blood flow to the lungs resulting in arterial pressure for an infant.
• Simultaneous pressure changes due to breathing and separation from the mother forces blood down, while resistance lowers.
• Ductus closes in hours/days reducing pressure and arterial blood
• Effects are diminished and there may be fainting/collapsing
• Lungs being affected results in pulmonary edema.

Heart Sounds: Machinery Murmur

• Blood flow can at times lead to certain sounds that can affect the body.

Surgical Treatment With Heart Problems

• Involves an extensive array of operations to remove issues and repair, many issues may arise that need attention and possible solutions to these medical disorders.

Tetralogy of Fallot- A Right-To-Left Shunt

Four different abnormalities occur simultaneously:

• 1. The aorta originates from the right ventricle rather than the left, or it overrides a hole in the septum.
• 2. much lower than normal amounts of blood pass into the lungs; instead, most of theblood passes directly into the aorta, thus bypassing the lungs
• 3. Blood from the left ventricle flows through a ventricular septal hole into the right ventricle and theninto the aorta or directly into the aorta that over-rides this hole.
• 4. Because the right side of the heart must pump large quantities of blood against the high pressure in the aorta, its musculature is highly developed, causing an enlarged right ventricle. Dysfunction is caused through the process of blood without oxygenation.

Surgical Treatment

Is used to treat this condition, which will often raise chances from between 3-4 years to 50 years of life after operation.

Causes of Congenital Anomalies

Congenital defects are often hereditary. May have underlying components, which can increase issues from time to time.

Use of Extracorporeal Circulation During Cardiac Surgery

This allows doctors/surgeons access to operate on the heart, allowing them to address complicated conditions if and when they arise.

Hypertrophy of the Heart in Valvular and Congenital Heart Disease

• Can be used to better treat the body, and issues related to any conditions that might effect it and cause detriment to the bodies overall effectiveness and functioning.

Detrimental Effects of Late Stages of Cardiac Hypertrophy

• Hypertrophy can occur leading to heart failure. One reason for this is that the coronary vasculature typically does not increase to the same extent as the mass of cardiac muscle increases.The heart also has a significant relationship the development of fibrosis.