Test: Murmurs and Heart Sounds - NEET PG MCQ

HOCM is characterised by asymmetrical septal hypertrophy, resulting in the formation of left ventricular (LV) outflow tract obstruction. This is influenced by the unique banana-shaped cavity of the left ventricle, where the blood volume within the LV chamber determines the extent of the outflow obstruction.

• The hypertrophied septum constricts the outflow tract leading into the aorta.
  
• A greater volume of blood in the LV alleviates the outlet obstruction.
• With reduced obstruction, the murmur is less pronounced.

When standing, the venous return diminishes, resulting in a lower blood volume within the LV chamber. This decrease in blood volume increases the LV outlet obstruction, causing the murmur to intensify.

S₂ on the phonocardiogram aligns with the conclusion of the T wave, at which point the aortic and pulmonic valves close.

• The label A in the diagram corresponds to the qRS complex, indicating the commencement of ventricular systole. At this moment, the aortic and pulmonic valves are opening, referred to as the ejection click.
• The label B in the diagram marks the end of the T wave, signifying the conclusion of ventricular systole. During this phase, the aortic and pulmonic valves are closing, known as S₂.
• The label C in the diagram represents the P wave, indicating the occurrence of atrial systole, which contributes to 30% of the ventricle's filling.

The clinical manifestation of exertional syncope, angina equivalent, and dyspnoea in the elderly suggests a diagnosis of valvular aortic stenosis. The auscultatory observation reveals a harsh ejection systolic murmur that radiates to the carotids.

• A soft S₂ is noted, which results from the reduced mobility of a stenosed valve.
• Choice B is incorrect as a narrow split S₂ or a paradoxical split S₂ is typically heard in aortic stenosis.
• Choices C and D are also incorrect due to the presence of the ejection systolic murmur associated with aortic stenosis.

The Graham Steell murmur arises from the expansion of the pulmonic valve ring and is observed in individuals with mitral valve disease, as well as those experiencing severe pulmonary artery hypertension. This murmur is characterised by a high-pitched, diastolic, decrescendo blowing sound that can be heard along the left sternal border.

Austin flint murmur results from significant aortic regurgitation. It arises from the diastolic movement of the anterior leaflet of the mitral valve caused by the aortic regurgitant stream. This condition generates a soft, low-pitched, rumbling murmur that occurs in the mid to late diastolic phase.

A continuous murmur can be detected during both systole and diastole, reaching its highest intensity at S2. To classify it as a continuous murmur, both of these conditions must be met.
Causes include:

• PDA
• AV fistula (Coronary, Pulmonary, Systemic)
• Aorto-pulmonary window
• Coarctation of the aorta
• Venous hum
• Rupture of the sinus of Valsava
• Pregnancy (Mammary souffle)
• Peripheral pulmonary artery stenosis associated with Williams syndrome.

The Ross Procedure is a specific type of aortic valve surgery in which the affected aortic valve is substituted with the patient's own pulmonary valve.
Subsequently, the pulmonary valve is replaced with a cryopreserved cadaveric pulmonary valve.

• For children and young adults, as well as older patients who are particularly active, this procedure presents various benefits compared to conventional aortic valve replacement using artificial prostheses.

The term 'midsystolic click' is nearly interchangeable with the prolapse of the mitral valve into the left atrium during systole. This phenomenon typically arises from myxomatous degeneration of the valve, leading to elongation of the valve and/or chordae tendinae. The primary issue stems from an abnormal relationship between the length of the mitral apparatus and the volume of the left ventricular chamber:

• The mitral valve is considered 'too long' relative to the size of the ventricular chamber.
• As ventricular systole progresses and the volume of the ventricle decreases, the valve cannot remain adequately positioned.
• This causes the valve to slip, and when it is caught again by the subvalvular tissue, the abrupt halt in motion produces a high-frequency sound known as the midsystolic click.
• The midsystolic click can actually manifest at nearly any point during systole, depending on the dimensions of the mitral apparatus and the volume of the left ventricle.

Reverse split S₂ indicates that the aortic valve closes significantly late, to the extent that it shuts after the pulmonic valve.

• This typically occurs in cases of severe aortic stenosis, where the obstruction at the valve increases the workload of the left ventricle.
• The prolonged ejection time results in a delayed closure of the aortic valve.
• This delay causes the split to narrow.

In mitral stenosis, a prominent S₁ is observed. In pulmonary artery hypertension, a loud P₂ can be detected. In pulmonic stenosis, a single S₂ is noted.

Erb's point serves as the auscultation site for heart sounds and murmurs. It is situated at the following locations:
Third intercostal space at the left lower sternal border

• Aortic area: second right interspace near the sternum
• Pulmonic area: second left interspace near the sternum
• Erb's point: third left interspace near the sternum
• Tricuspid area: fifth left interspace near the sternum
• Mitral area (apical): fifth left interspace medial to the MCL

The fundamental principle in medical education is that all events on the right side of the heart increase during inspiration, with the exception of the pulmonic ejection click associated with pulmonic stenosis. Conversely, left-sided events diminish with expiration.

• The ejection click that introduces the murmur of pulmonary stenosis becomes quieter during inspiration.
• Pulmonary stenosis causes hypertrophy of the right ventricle, which results in stiffening of that chamber.
• When blood flows into the right ventricle during inspiration, the thickened chamber fails to distend properly, leading to a rise in pressure within the chamber.
• This pressure increase causes the pulmonary valve to be partially open.
• As the right ventricle contracts with the pulmonary valve partially open, its movement is reduced, resulting in the ejection click associated with maximal opening being softer and occurring earlier.

The Triangle of Auscultation is delineated by the following boundaries:

• Superiorly and medially, by the inferior part of the Trapezius.
• Inferiorly, by the Latissimus Dorsi.
• Laterally, by the medial border of the scapula.

The superficial floor of the triangle is constituted by the Serratus anterior and the lateral portion of the erector spinae muscles. Beneath these muscles lie:

• the osseous sections of the 6th and 7th ribs,
• the internal and external intercostal muscles.

Typically, the Triangle of Auscultation is obscured by the Scapula. To enhance the visibility of the triangle and facilitate the auscultation of respiratory sounds using a stethoscope, patients are instructed to cross their arms over their chest. This action medially rotates the scapulae while the trunk is bent forward, mimicking a fetal position.

A continuous murmur arises due to a persistent pressure gradient between two cardiac chambers or blood vessels throughout both systole and diastole. The characteristics of these murmurs typically include:

• Starting in systole
• Enveloping the second heart sound (S2)
• Continuing for a portion of diastole

Continuous murmurs remain unaffected by dynamic auscultation techniques such as squatting, as the murmur is determined by the pressure gradient. They can be challenging to differentiate from isolated systolic and diastolic murmurs in patients with mixed valvular heart disease. A well-known example of a continuous murmur is linked to a patent ductus arteriosus, which is generally audible in the second or third interspace, slightly distant from the sternal border.
Other potential causes of a continuous murmur include:

• Ruptured sinus of Valsalva aneurysm leading to an aortic-right atrial or right ventricular fistula
• Coronary or great vessel arteriovenous fistula
• Arteriovenous fistula created for dialysis access
• The cervical venous hum, typically heard in children or adolescents in the supraclavicular fossa, can be suppressed by applying firm pressure to the diaphragm of the stethoscope, especially when the individual turns their head towards the examiner
• The mammary souffle during pregnancy, which is associated with increased arterial blood flow through engorged breasts; the diastolic component of this murmur can also be suppressed with firm pressure on the stethoscope

Low pitch heart sounds include:

• S₃
• S₄
• Tumour plop sound (atrial myxoma)

Mid-systolic clicks are detected in mitral valve prolapse during systole and are characterised by high pitch. The pericardial knock (PK) is also a high-pitched sound that occurs slightly after the opening snap.
This timing aligns with the sudden halt of ventricular expansion following tricuspid valve opening and is associated with an exaggerated y descent observed in the jugular venous waveform of patients with constrictive pericarditis.
A tumour plop is a lower-pitched sound that may be heard in patients with atrial myxoma. It might only be noticeable in specific positions and results from the diastolic prolapse of the tumour across the mitral valve.

Reverse split S₂ indicates that the aortic valve closes significantly later, to the extent that it shuts after the closure of the pulmonic valve. Typically, the aortic valve closes before the pulmonic valve. This phenomenon occurs in cases of severe aortic stenosis, where the obstruction at the valve increases the workload of the left ventricle.

• The prolonged ejection time results in a delayed closure of the aortic valve.
• This delay in closure causes the split to narrow.

In instances of mitral stenosis, a pronounced S₁ is observed. Conversely, in pulmonary artery hypertension, a loud P₂ is noted. In cases of pulmonic stenosis, a single S₂ can be detected.

A functional murmur (also referred to as an innocent or physiological murmur) is a type of heart murmur primarily resulting from physiological conditions outside the heart, rather than from structural defects within the heart itself.
Characteristics of a functional murmur include:

• Soft sound, less than 3/6 in intensity (it is important to note that intensity does not necessarily indicate severity, even when structural heart disease is present).
• Often dependent on position; murmurs may be heard while lying down and can disappear when the individual is upright or seated.
• Typically found in otherwise healthy individuals, with no concerns regarding growth or symptoms of heart failure, such as dyspnoea on exertion.
  • In infants, inquire if the baby tires during feeding, becomes diaphoretic, or shows a rapid respiratory rate.
  • In older children, this can be assessed by asking if the child can keep up with peers during play.
• Occurs during systole or continuously throughout both systole and diastole (murmurs that occur only during diastole are always pathological).
• Physiological splitting of S2 (the A2 and P2 components should only be distinguishable during inspiration and should merge during expiration).
• No palpable thrill (a thrill is a vibration caused by turbulent blood flow).

• Pulmonary hypertension unless demonstrated otherwise
• Eisenmenger's syndrome resulting from ASD, VSD, or PDA
• Multiple pulmonary thrombi

During a systolic murmur observed in a stenotic condition such as aortic stenosis, the left ventricle must exert additional force to open the narrowed valve.

• The vigorous opening of these valves results in a pronounced ejection click.
• This should not be mistaken for mid-systolic clicks, which occur with mitral valve prolapse.

All murmurs diminish with Valsalva manoeuvre, standing, and inhalation of amyl nitrite, except for HOCM, which becomes more pronounced, and MVP, which extends in duration.