Show notes
Congenital heart disease is the most common birth defect, affecting 1 in 100 babies. Amongst these ventricular septal defects are very common with the majority of patients living into adulthood. In this episode we will be reviewing key features of VSDs including embryologic origin, anatomy, physiology, hemodynamic consequences, clinical presentation and management of VSDs. Dr. Tommy Das (CardioNerds Academy Program Director and FIT at Cleveland Clinic), Dr. Agnes Koczo (CardioNerds ACHD Series Co-Chair and FIT at UPMC), and Dr. Anu Dodeja (Associate Director for ACHD at Connecticut Children’s) discuss VSDs with expert faculty Dr. Keri Shafer. Dr. Shafer is an adult congenital heart disease specialist at Boston Children’s Hospital, and an assistant professor of pediatrics within Harvard Medical School. She is a medical educator and was an invited speaker for the inaugural CardioNerds Sanjay V Desai Lecture, on the topic of growth mindset. Script and notes were developed by Dr. Anu Dodeja. Audio editing by CardioNerds Academy Intern, Shivani Reddy.
The CardioNerds Adult Congenital Heart Disease (ACHD) series provides a comprehensive curriculum to dive deep into the labyrinthine world of congenital heart disease with the aim of empowering every CardioNerd to help improve the lives of people living with congenital heart disease. This series is multi-institutional collaborative project made possible by contributions of stellar fellow leads and expert faculty from several programs, led by series co-chairs, Dr. Josh Saef, Dr. Agnes Koczo, and Dr. Dan Clark.
The CardioNerds Adult Congenital Heart Disease Series is developed in collaboration with the Adult Congenital Heart Association, The CHiP Network, and Heart University. See more
Disclosures: None
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Pearls - Ventricular Septal Defects
Most common VSDs: Perimembranous VSD
The shunt volume in a VSD is determined largely by the size of the defect and the pulmonary vascular resistance. VSDs cause left to right shunt. The long-term effects are left sided chamber dilation, as is the case with PDAs (post-tricuspid shunts)
VSDs can be associated with acquired RVOTO, double chamber right ventricle, LVOTO/sub aortic membrane formation, and aortic regurgitation from aortic valve prolapse.
Eisenmenger syndrome results from long-term left-to-right shunt, usually at higher shunt volumes. The resulting elevated pulmonary artery pressure is irreversible and leads to a reversal in the ventricular level shunt, desaturation, cyanosis, and secondary erythrocytosis.
Endocarditis prophylaxis is not indicated for simple VSD. It is required for 6 months post VSD closure, in patients post VSD closure with a residual shunt and in Eisenmenger patients with R—L shunt and cyanosis.
Show notes - Ventricular Septal Defects
Notes (developed by Dr. Anu Dodeja):
What are types OF VSD? (Please note that there are several nomenclatures)
Perimembranous VSDMost common type of VSD - 80% of VSDsOccurs in the membranous septum and can be associated with inlet or outlet extensionLocated near the tricuspid and aortic valves, often time can be closed off by tissue from the septal leaflet of the tricuspid valve and associated with abnormalities in the septal leaflet of the tricuspid valve secondary to damage from the left to right shuntCan be associated with acquired RVOTO, double chamber right ventricle, LVOTO/sub aortic membrane formation
On TTE, the parasternal short axis view at the base demonstrates this type of VSD at the 10-12 o’clock position.
Muscular VSDSecond most common VSD - 15-20% of VSDsCompletely surrounded by muscle, usually restrictive, can be multiple defects
These usually close spontaneously by direct apposition of the muscular borders.
Supracristal (also known as sub-arterial/sub-pulmonary/conal/juxta-arterial)Represent 5% of VSDsLocated beneath the semilunar valves in the conal or outlet septumDo not usually close spontaneouslyMay be associated with progressive aortic regurgitation due to prolapse of the right aortic cusp and aneurysm of the sinus of Valsalva.Aortic valve prolapse:Prolapsing of the right or non-coronary aortic valve cusp may initially reduce the degree of left-to-right shunt but results in development of aortic regurgitationAortic valve prolapse usually involves the right coronary cusp and less frequently the non-coronary cusp In its early stage: prolapse occurs only in the systolic phase because of the venturi effect resulting from the rapid shunt flow through the defectIn later stages the prolapse also present last with the valve cusps cannot withstand intra-aortic pressure. Eventually the prolapsing aortic valve becomes incompetent because of the significant damage to the valve cusps and annulusAs a prolapsing aortic valve may completely close the ventricular septal defect, shunt physiology may disappear with progressive development of aortic regurgitationSome case reports of aneurysms of sinus of Valsalva indicate that the original defect might be ventricular septal defect complicated by aortic valve prolapse with complete obliteration of the defectRarely the prolapsed valve cusp may perforate with resultant aortic regurgitation into the right ventricle
On TTE, the parasternal short axis view at the base demonstrates these VSDs at the 12 to 2 o’clock position
Inlet/AV canal typeOccur in the inlet portion of the ventricular septum immediately inferior to the AV valve apparatusCan be associated with a common AV valveMay be associated with AV septal malalignment and straddlingDue to endocardial cushion defect
AVSD are the most common CHD in patients with Down syndrome.
Malalignment type of VSDsOccur in the output or infundibular septumMalalignment of the outlet septum may occur either anteriorly towards the right ventricle or posteriorly towards the left ventricleThe anterior malalignment of the outlet septum is the most common type of malalignment. In this situation the outlet septum is pulled anteriorly towards the right ventricular outflow tract resulting in a large ventricular septal defect with overriding aortic valve and pulmonary stenosis as seen in Tetralogy of Fallot.
Posterior malalignment results in sub-aortic obstruction and can be associated with Coarctation of aorta and IAA.
Rarely patients can have a LV-RA shunt known as a Gerbode defectAbsence of the atrioventricular septal tissue resulting in an isolated LV to RA shuntCan occur when the VSDs located slightly more superior to the tricuspid valve apparatusCan also be due to deficient tricuspid valve septal leafletCan occur as a post-operative complication
The effective impact of such a shunt is to produce right ventricular volume overload and elevated right atrial pressure and are at increased risk for endocarditis.
If VSDs are left to right shunts, why do they cause left sided chamber dilation?
The timing of the left to right shunt in ventricular septal defects is predominantly in ventricular systole so the blood goes left to right but is pumped directed out the PA resulting in increased pulmonary venous return to the LA and LV.
As such, the RV does not directly see the increased blood volume.
There are a few cases in which there maybe RA dilation including: Gerbode defect, Eisenmenger syndrome, and DCRV.
What are the indications for VSD repair?
Evidence of left ventricular volume overload and hemodynamically significant shunt (Qp: Qs 1.5:1), if PA pressures are less than 50% systemic and pulmonary vascular resistance is less than 1/3 systemic (2018 ACHD Guidelines)
What is the relevance of the conduction system in the approach to VSDs?
The nature of the VSD will also allow for understanding the course of the conduction system.
Perimembranous defects - the bundle of His runs along the posterior and inferior rim of the VSD. Post-operatively, patients may have a right bundle branch block pattern on ECG. Patients are at risk for surgical CHB which can occur even years post-VSD closure.
Inlet type VSD - the bundle of His runs anterior and superior to the defect which can be seen as a northwest axis deviation on EKG (-90 to 180°). Patients are at risk for surgical CHB, which can occur even years post-VSD closure.
Surgically induced AV block is less likely with a muscular or supracristal/outlet type of defects because they are distant from the AV nose and bundle of His.
What are clinical exam features of VSDs?
VSDs cause a holosystolic murmur if pressure in the right ventricle is lower than the left ventricle throughout systole, resulting in a holosystolic left-to-right shunt
Small restrictive VSD will have a loud, harsh, holosystolic murmur usually with a thrill in the third or fourth ICS along the LSB
Muscular VSDs can have shorter systolic murmurs
Absence of VSD murmur, with a loud P2, RV heave is indicative of elevated RV pressures with equalization in ventricular pressures indicating Eisenmenger syndrome. These patents will also have cyanosis, clubbing, over time can have a holosystolic murmur due to functional TR
Systolic ejection murmur at the LUSB may be indicative of RVOTO
Presence of a diastolic murmur in the RUSB, wide pulse pressure, and prominent carotid pulses indicate AR
What are imaging characteristics of VSDs?
First and foremost will be location and size of the VSD
Parasternal long axis view:Distinct visualization of muscular, membranous, and supracristal/infundibular VSDsPerimembranous and supracristal defects are seen below the aortic valveCan also show aortic cusp prolapse and associated aortic regurgitation