Heart Sounds

Question 1

Four Heart Sounds

Answer 1

• hese sounds originate due to the rapid acceleration and deceleration of blood giving rise to vibrations of an audible frequency in the heart and neighbouring structures associated with certain event in the cardiac cycle.
• The sounds are numbered from the onset of systole and are referred to as S1, S2, S3, and S4

Question 2

S1

Answer 2

• corresponds to the onset of systole and is heard at the time of AV valve closure and the onset of ventricular contraction

Question 3

S2

Answer 3

• corresponds to the end of systole and is heard at the time of outflow valve closure

Question 4

S3

Answer 4

corresponds to the rapid passive filling phase of the ventricles

Question 5

S4

Answer 5

corresponds to the phase of active ventricular filling.

Question 6

Sounds in Horses v. Dogs/Cats

Answer 6

• In normal horses typically three or four of the normal heart sounds are audible at lower heart rates.
• In dogs and cats normally only the first two heart sounds S1 and S2 are audible.
• When either S3 or S4 are audible in dogs and cats a total of three sounds will be heard this is described as a gallop rhythm and is always abnormal

Question 7

Heart Mumurs

Answer 7

• An additional noise heard in the cardiac cycle due to the turbulent flow of blood within the heart or great vessels is described as a murmur.
• Murmurs are described according to where they are most clearly heard and also when in the cardiac cycle
• Murmurs are graded in intensity according to how loud they are with relation to the other heart sounds.

Question 8

Systole v. Diastole

Answer 8

• The period of time between S1 and S2 is systole.
• The period of time between S2and the following S1 is diastole.

Question 9

Decresendo Mumur

Answer 9

• As is typical of diastolic murmurs this murmur diminishes in intensity during it’s course.
• This would be described as a decrescendo murmur.

Question 10

Pulmonary Stenosis

Answer 10

• is a condition characterized by obstruction to blood flow from the right ventricle to the pulmonary artery.
• This obstruction is caused by narrowing(stenosis) at one or more points from the right ventricle to the pulmonary artery.
• Pulmonic stenosis is one of the 3 most common congenital heart diseases in dogs (the other 2 are patent ductus arteriosus and aortic stenosis)
• Narrowing of the pulmonic valve results in high velocity blood flow the other side of the valve (in the main pulmonary artery), which results in blood flow turbulence and a heart murmur.
• The point of maximal intensity of the murmur is over the left heart base. The murmur intensity directly correlates with the severity of the disease, so that the more severe the obstruction, the higher the velocity of blood flow, and the louder the murmur.
• The localization and characteristics of a pulmonic stenosis murmur are very similar to that of aortic stenosis and their differentiation on clinical examination is challenging

Question 11

Cardiac Rythm in Dogs

Answer 11

• Dogs do not normally have a regular cardiac rhythm. The rhythm is often regularly irregular
• beats come in regular cycles with slowing of the rate between. This is quite normal.

Question 12

Mitral Insufficiency or Mitral Regurgitation

Answer 12

• a disorder of the heart in which the mitral valve does not close properly when the heart pumps out blood.

Question 13

Which murmur would be most likely to be associated with a patent ductus arteriosus?

Answer 13

PDAs typically have continuous murmurs rather than just systolic murmurs.

Question 14

What would distinguish a grade IV from a grade V murmur?

Answer 14

A palpable thrill on the skin surface

Question 15

Holosystolic Murmur

Answer 15

• A holosystolic murmur begins at the first heart sound (S1) and continue to the second heart sound (S2), as illustrated in the phonocardiogram.
• Typically high-pitched, these murmurs are usually caused by ventricular septal defect, mitral regurgitation or tricuspid regurgitation, as discussed below
• A heart murmur between S1 and S2 is a systolic murmur. There is turbulent blood flow during ventricular contraction, that is, the time elapsing between atrioventricular and semilunar valvular closure.
• If the murmur is louder than S1 and S2, and extends throughout the whole of systole, which defines it as loud and holosystolic, respectively. The most common cause of a loud holosystolic murmur with point of maximal intensity over the left cardiac apex is mitral regurgitation.

Question 16

Differential diagnoses for mitral regurgitation

Answer 16

• Degenerative mitral valve disease (DMVD)
• mitral annulus dilatation secondary to dilated cardiomyopathy
• mitral valve dysplasia and endocarditis
• The first two are by far the most frequent causes of mitral regurgitation.

Question 17

Diagnosing a Pulmonary Stenosis Murmur

Answer 17

• With pulmonic stenosis the murmur tends to radiate dorsally and the femoral pulses are generally normal, while in aortic stenosis the murmur radiates to the thoracic inlet (carotid arteries) and in severe cases the pulses are weak.
• Echocardiography is necessary to diagnose and stage congenital heart diseases, and this should ideally be performed by a specialist cardiologist.

Question 18

Balloon Valvuloplasty

Answer 18

• A valvuloplasty, also known as balloon valvuloplasty orballoon valvotomy, is a procedure to repair a heart valve that has a narrowed opening
• A doctor uses a thin flexible tube (catheter) that is inserted through an artery in the groin or arm and threaded into the heart.
• When the tube reaches the narrowed mitral valve, a balloon device located on the tip of the catheter is quickly inflated.
• The narrowed or fused mitral valve leaflets are separated and stretched open as the balloon presses against them.
• This process increases the size of the mitral valve opening and allows more blood to flow from the left atrium into the left ventricle

Question 19

A loud heart murmur with point of maximal intensity on the right hemithorax

Answer 19

suggestive of a ventricular septal defect or severe tricuspid regurgitation

Question 20

Ventricular septal defects

(VSDs)

Answer 20

• are the most common congenital heart defect in cats, and the 4th most common congenital heart disease in dogs.
• Most VSDs in dogs are located in the interventricular septum just ventral to the aortic valve, and they are usually small so that relatively little blood flow crosses the defect.
• The systolic pressure in the left ventricle is normally much higher than in the right ventricle, so that a jet of high velocity blood flow crosses from the left ventricle to the right ventricle (left-to-right shunting), creating a very loud murmur heard best on the right hemithorax, cranially and close to the sternum.
• The murmur intensity is inversely related to the severity of the disease, so that the louder the murmur, the smaller the VSD.

Question 21

Small VSD v. loud VSD

Answer 21

• With a small VSD, the prognosis is usually excellent and no medical or surgical therapy is required.
• A loud systolic heart murmur over the right hemithorax in a young animal is suggestive of a ventricular septal defect, but echocardiography performed by a cardiology specialist is always required for a definitive diagnosis.

Question 22

A continuous heart murmur at the left heart base

Answer 22

• highly suggestive of a patent ductus arteriosus
• PDA is one of the most common congenital heart diseases in dogs. It is caused by a failure of the ductus arteriosus to close after birth, so that there is a persistent communication between the aorta and pulmonary artery.
• Because aortic pressures are higher than pulmonary artery pressures, there is a constant flow of blood from left (aorta) to right (pulmonary), and the turbulence continues throughout the cardiac cycle.
• Continued aortic blood flow into the pulmonary artery in diastole results in abnormally low diastolic aortic pressure, and a greater than normal difference between systolic and diastolic aortic pressures (hence the hyperdynamic pulses)

Question 23

Patent Ductus Arteriosus

Answer 23

• A PDA typically causes a very loud continuous murmur with a precordial thrill* at the left heart base (in the dorsal axillary region, under the triceps muscle).
• to avoid missing important heart murmurs always palpate the thorax over the heart (the ‘precordium’) before auscultating a dog, especially a puppy. This will help you to detect any cardiac thrill and indicate the point of maximal intensity of the murmur.
• The murmur is generally louder in systole (higher pressure gradient) than in diastole, because the difference in pressures between the aorta and pulmonary artery is higher in systole.
• Although the characteristics of the murmur (timing, location), breed and age are generally pathognomonic for a PDA, specialist echocardiography should be always performed to confirm the diagnosis, evaluate severity of the disease, and exclude other concurrent congenital heart diseases.
• Treatment is directed at closing the patent ductus.
• This can be done with a catheter interventional procedure (positioning a device in the ductus to close it) or by surgical ligation

Question 24

Echocardiography

Answer 24

• An echocardiogram, often referred to as a cardiac echo or simply an echo, is a sonogram of the heart. (It is not abbreviated as ECG, because that is an abbreviation for an electrocardiogram.)
• Echocardiography uses standard two-dimensional, three-dimensional, and Doppler ultrasound to create images of the heart

Question 25

Auscultation of chaotic heart sounds with pulse deficits

Answer 25

• provides a clue to the presence of atrial fibrillation; this should be confirmed with an electrocardiogram (ECG).
• Key features on an ECG include an irregular, fast rhythm, narrow QRS complexes and no obvious P waves.
• The majority of dogs with atrial fibrillation will have underlying structural heart disease and limiting the tachycardia associated with atrial fibrillation is important in managing clinical signs.
• ascites can be a consequence of congestive heart failure.

Question 26

Dilated Cardiomyopathy

Answer 26

• (DCM) is a condition in which the heart becomes enlarged and cannot pump blood effectively
• A likely cause for mitral regurgitation
• Dilated cardiomyopathy is the most common primary myocardial disease in dogs and is typically seen in middle aged, large breed dogs.
• Irish Wolfhounds are a predisposed breed.
• Note that the intensity of the murmur does NOT correlate with the severity of the disease in DCM.

Question 27

Systole

Answer 27

During systole, the heart’s two ventricles contract (squeeze)

Question 28

Arrythmias

Answer 28

• Heart arrhythmia, also known as irregular heartbeat or cardiac dysrhythmia, is a group of conditions where the heartbeat is irregular, too slow, or too fast.

Arrhythmias are broken down into:

• Slow heartbeat: bradycardia.
• Fast heartbeat: tachycardia.
• Irregular heartbeat: flutter or fibrillation

Answer 29

• Sinus arrhythmia is a phasic variation in heart rate, usually in association with respiration. The heart rate increases in inspiration, and decreases in expiration.
• It is a common finding in healthy dogs, and is caused by the normal predominance of vagal tone.
• Non-brachycephalic dogs are unlikely to have congestive heart failure if sinus arrhythmia is present, as sinus arrhythmia is lost with any increase in sympathetic tone.
• This means that sinus arrhythmia is only likely to be detected in relatively calm dogs.
• Sinus arrhythmia is not considered normal in cats in a hospital environment.

Question 30

Discospondylitis

Answer 30

• Discospondylitis, also spelled as diskospondylitis, is an infection of the vertebrae and the surrounding cartilaginous discs.
• It is also referred to as vertebral osteomyelitis and the swelling created by this disease can cause severe pain as well as nerve damage in afflicted dogs if left untreated.

Question 31

What causes Sinus Arrhythmia?

Answer 31

• Sinus arrhythmia results from variation in the rate of spontaneous depolarization of the sino-atrial node, associated with phasic variation in vagal tone.
• It occurs when vagal tone predominates, either because sympathetic tone is low, or when vagal tone is particularly increased.
• It is common in calm, healthy dogs but it can also be seen with abnormally elevated vagal tone due to severe respiratory disease (particularly upper respiratory tract obstruction), severe gastrointestinal disease, central nervous system disease or increased intraocular pressure.
• Brachycephalic breeds often have upper respiratory tract obstruction, which causes increased vagal tone.
• In these breeds sinus arrhythmia may persist even in the presence of congestive heart failure.

Question 32

Which of the following is a frequent cause of cardiac murmurs in cats with cardiomyopathy?

Answer 32

• Dynamic Left Ventricular Outflow Tract Obstruction
• Dynamic left ventricular outflow tract obstruction is a common cause of heart murmurs in cats with hypertrophic cardiomyopathy (HCM).
• Abnormal motion of the anterior (septal) mitral valve leaflet during systole obstructs ejection of blood into the aorta and also causes mitral regurgitation, both resulting in a systolic heart murmur.

Question 33

What is the most common acquired cardiac disease in cats?

Answer 33

• Hypertrophic Cardiomyopathy
• HCM is the most common form of cardiac disease in cats

Question 34

systolic anterior motion of the mitral valve (‘SAM’)

Answer 34

• Cats with HCM often have SAM, causing dynamic left ventricular outflow tract obstruction and mitral regurgitation.
• Both outflow tract obstruction and mitral regurgitation cause high velocity blood flow that results in turbulence and consequently a heart murmur.
• The obstruction is influenced by sympathetic tone, so that the obstruction is worse (and the murmur is louder) with high sympathetic tone.
• This means that cats with HCM often have a heart murmur that varies in intensity.
• Note that healthy cats can also have a murmur that varies in intensity without any structural heart disease at all. This is a common phenomenon, and is called a ‘functional’ murmur.

Question 35

What is NOT a differential for a cardiac murmur in a cat?

Answer 35

• Diabetes Mellitus

Question 36

2 Most Common Types of Murmurs in Cats

Answer 36

• The two most common types of heart murmurs in cats are ‘innocent’ heart murmurs (also called functional or physiological murmurs, where there is no structural cardiac abnormality) and murmurs associated with hypertrophic cardiomyopathy (HCM).
• Systolic anterior motion of the mitral valve (SAM) causing dynamic left ventricular outflow tract obstruction is one of the most common causes of heart murmurs in cats with HCM.
• A murmur may also be heard in anaemic cats, as increased cardiac output and decreased blood viscosity can result in blood flow turbulence.
• Hyperthyroid and hypertensive cats also often have a heart murmur.
• Congenital heart disease should be considered in cats with very loud murmurs. Note that valve disease is rare in cats, in contrast to dogs

Question 37

Can cardiac disease be ruled out in a cat without a cardiac murmur?

Answer 37

• NO
• Some cats with HCM and other cardiomyopathies do not have any heart murmur at all, and there is no correlation between the loudness of the murmur and the severity of heart disease in cats.
• Bengals are thought to be predisposed to HCM
• A heart murmur is the sound caused by a turbulence of blood flow within the heart. Heart murmurs are common in cats, found in approximately 15-40% of the healthy feline population. A murmur can be found in normal cats (‘innocent’/physiological murmur).
• Conversely, some cats with cardiomyopathy have no heart murmur. Heart murmurs in cats may also be dynamic in nature, meaning they can be heard at one vet visit and not at the next. Currently, the most reliable method of diagnosing cardiomyopathy is echocardiography.

Question 38

What is a ‘gallop’ sound?

Answer 38

• an S3 and/or S4 sound

Question 39

When is a gallop sound detected in cats?

Answer 39

• Advanced cardiac disease with increased left ventricular filling pressures, In atrial fibrillation secondary to a fourth heart sound (S4)

Question 40

What is the clinical significance of a gallop sound?

Answer 40

• A gallop sound is produced by reverberations associated with filling of the left ventricle.
• They can be associated with early (passive) left ventricular filling (third heart sound, or S3) or with active atrial contraction (4th heart sound, or S4).
• S3 and S4 sounds are normally audible in horses, but are not normal in cats or dogs.
• Gallop sounds are NOT arrhythmias, and in cats they are most often heard in association with cardiomyopathies.
• They are particularly common when left atrial pressures are high, so they indicate a high risk of congestive heart failure.

Question 41

Restrictive Cardiomyopathy

Answer 41

• Restrictive cardiomyopathy (RCM) is a rare form of heart muscle disease that is characterized by restrictive filling of the ventricles.
• In this disease the contractile function (squeeze) of the heart and wall thicknesses are usually normal, but the relaxation or filling phase of the heart is very abnormal

Question 42

Gallop Sound

Answer 42

• A gallop sound is caused by an extra third (S3) or fourth (S4) heart sound.
• These are diastolic sounds not normally detected in healthy small animals.
• The differentiation between S3 and S4 in cats is generally impossible due to their fast heart rates.
• Gallop sounds are a very important clinical finding, because they generally reflect the presence of advanced structural cardiac disease and a present or imminent risk of congestive heart failure.
• In cats, gallop sounds are more specific for the presence of significant cardiac disease than heart murmurs.

Question 43

Premature Beat

Answer 43

A premature ventricular contraction (PVC)—also known as a premature ventricular complex, ventricular premature contraction (or complexor complexes) (VPC), ventricular premature beat (VPB), or ventricular extrasystole (VES)—is an event where the heartbeat is initiated by Purkinje fibers in the ventricles rather than by the sinoatrial node, the normal heartbeat initiator.

• The most obvious auscultation finding with premature beats in cats is often the pause that follows the premature beat

Question 44

What is the most frequent cause for arrhythmias in cats?

Answer 44

• Severe Cardiac Disease
• Arrhythmias in cats are commonly associated with cardiomyopathy.
• Arrhythmias is cats are a very important clinical finding, because they generally reflect the presence of advanced structural cardiac disease and the need for further diagnostic tests (e.g. measurement of cardiac biomarkers, echocardiography)