Physiological Adaptation Q 90
A murmur is heard at the second left intercostal space along the left sternal border. Which valve area is this?
A. Aortic
B. Mitral
C. Pulmonic
D. Tricuspid
Correct Answer: C. Pulmonic
Abnormalities of the pulmonic valve are auscultated at the second left intercostal space along the left sternal border. Murmurs of the cardiac system develop due to alterations in blood flow or mechanical operation. Murmurs develop from a multitude of mechanisms. Typical cases include low blood viscosity from anemia, septal defects, failure of the ductus arteriosus to close in newborns, excessive hydrostatic pressure on cardiac valves causing valve failure, hypertrophic obstructive cardiomyopathy, and valvular specific pathologies.
Option A: Aortic valve abnormalities are heard at the second intercostal space, to the right of the sternum. Aortic regurgitation, also known as aortic insufficiency, is a decrescendo blowing diastolic murmur heard best at the left lower sternal border, heard when blood flows retrograde into the left ventricle. This is most commonly seen in aortic root dilation and as sequelae of aortic stenosis.
Option B: Mitral valve abnormalities are heard at the fifth intercostal space in the midclavicular line. Mitral stenosis is a diastolic murmur, best heard at the left 5th midclavicular line. It is associated with infective endocarditis and chronic rheumatic heart disease. Mitral regurgitation is a systolic murmur, best heard at the left 5th midclavicular line with possible radiation to the left axilla. It is commonly associated with infective endocarditis, rheumatic heart disease, congenital anomalies, and inferior wall myocardial infarctions.
Option D: Tricuspid valve abnormalities are heard at the third and fourth intercostal spaces along the sternal border. Tricuspid stenosis is best heard at the lower left sternal border. Typical causes include infective endocarditis, seen in intravenous drug users, and carcinoid syndrome. Prolonged tricuspid stenosis may lead to right atrial enlargement and arrhythmias. Tricuspid regurgitation is systolic, auscultated at the lower left sternal border. It is also associated with intravenous drug users and carcinoid syndrome.