The murmur of a ventricular septal defect (VSD) is holosystolic and best heard over the “tricuspid area”, or the lower left sternal border, with radiation to the right lower sternal border because this is the area which overlies the defect.
A VSD is a connection between the left and right ventricles. Blood flows from the high pressure left ventricle to the lower pressure right ventricle during systole, producing a murmur. During a squatting (or hand grip) maneuver, total peripheral resistance is increased, forcing more blood through the defect and causing a louder murmur.
As reviewed by McConnell et al., atrial and ventricular septal defects, along with pulmonary or aortic outflow tract abnormalities and patent ductus arteriosus are pathologic causes of systolic murmurs found in children. Worrisome characteristics of pathologic murmurs that indicate referral to a pediatric cardiologist include a sound level of grade 3 or louder, a diastolic murmur or an increase in intensity when the patient is standing.
Penny and Vick discuss VSDs. They note that in patients with long-standing left to right shunting through the VSD, pulmonary vascular disease can develop in later childhood or in early adult life. If a large lesion is left uncorrected, over time the pressures in the right side(pulmonary system) increase to greater than systemic pressures leading to reversal of flow through the shunt and cyanosis. This is called Eisenmenger's syndrome.
Illustration A is an echocardiographic image of a moderate ventricular septal defect in the mid-muscular part of the septum. Flow is from the left ventricle (right on image) to the right ventricle (left on image).
Answer 2: PDA causes a "continuous flow" murmur or continuous "machine-like" murmur, not a holosystolic murmur.
Answer 3: The most characteristic feature of an atrial septal defect is the fixed split S2.
Asnwer 4: Tricuspid atresia is the absence of a communication between the RV and RA due to failure of the tricuspid valve to form. It would present at birth.
Answer 5: The murmur of aortic stenosis is typically a mid-systolic ejection murmur, heard best over the “aortic area” or right second intercostal space, with radiation into the right neck.
McConnell ME, Adkins SB 3rd, Hannon DW. Heart murmurs in pediatric patients: when do you refer? Am Fam Physician. 1999 Aug;60(2):558-65. Review. PubMed PMID: 10465230.
PMID:10465230 (Link to Abstract)
Penny DJ, Vick GW 3rd. Ventricular septal defect. Lancet. 2011 Mar 26;377(9771):1103-12. Epub 2011 Feb 23. Review.
PMID:21349577 (Link to Abstract)
USMLE World Step 1 QBank Question #2117. Copyright © USMLEWorld, LLC 2012.