Endocardial Cushion Defect / AVSD

Brief information about clinical manifestation and management of Endocardial Cushion Defect / atrioventricular defect

1. Endocardial Cushion Defect 9/5/2020 Harshitha Bsc.CVT   MCHP, Manipal   Clinical Manifestations 

2. History PARTIAL AVSD Patients with ASD are usually asymptomatic during childhood Dyspnoea, easy fatigability, recurrent RTI and growth retardation may be present early in life if associated with major MR or common atrium COMPLETE AVSD  Tachypnea and failure to thrive invariably occur early in infancy and virtually all patients have symptoms by 1 year of age if these symptoms do not develop early on the clinician should suspect premature development of pulmonary vascular obstructive disease

3. Physical examination Infants with ECD are usually  undernourished  and will show  signs of CHF.  This defect is common in infants with Down syndrome. Hyperactive precordium with a systolic thrill at the lower left sternal border  is common.  The S1 is accentuated, S2 is narrowly splits, and the P2 increases in intensity. A grade 3 to 4/6 holosystolic murmur  is usually audible along the lower left sternal border.  The  systolic murmur may transmit well to the left back and be heard well at the apex when mitral regurgitation (MR) is significant.  A mid-diastolic rumble may be present  at the lower left sternal border or at the apex as a result of relative stenosis of the tricuspid or mitral valve. 

4. ECG  “Superior” QRS axis with the QRS axis between -40 and -150 degrees is characteristic of the defect   Prolongation of the P-R interval is observed in approximately 25% of patients with AVSD (first-degree AV block ).    RVH or RBBB is present in all cases, and many patients have LVH, too.

5. ECG 1

6. ECG 2

7. Xray Cardiomegaly is always present and involves all four cardiac chambers.  Pulmonary vascular markings are increased, and the main PA segment is prominent.   The left cardiac border is straightened by a prominent right ventricular outflow tract.  In Down’s syndrome, the lateral chest X-ray may show a double manubrial ossification center and the posterioanterior projection may show absent or rudimentary 12th rib.  Hyperinflation of the lung may be present because of upper airway obstruction in patients with Down’s syndrome.

8. Echocardiography Apical and subcostal views  The apical and subcostal four-chamber views are most useful in evaluating the anatomy and the functional significance of the defect.  These views show both an ostium primum ASD and an inlet muscular VSD    Either the anterior bridging leaflet crosses the ventricular septum, or the right and left AV valve leaflets can be seen at the same level from the crest of the ventricular septum.   The full extent of the ASD and VSD can be imaged during systole when the common anterior leaflet is closed.  A combined use of the subcostal transducer position (i.e., about 45 degrees clockwise from a standard four-chamber view) and the parasternal short-axis examination may show a cleft in the mitral valve, the presence of bridging leaflets, the number of AV valve orifices and the AV valve leaflets. 

9. These views may also image the abnormal position of the anterolateral papillary muscle, which is displaced posteriorly from its normal position, and the number of papillary muscles.  The subcostal five-chamber view may image a goose-neck deformity, which is characteristic of an angiocardiographic finding   In real time, the subcostal and apical four-chamber views can image the chordal attachment of the anterior bridging leaflet to the crest of the ventricular septum (type A), to the right side of the septum (type B), or to a papillary muscle at the apex of the RV or on its free wall (type C)

10. Parasternal views Parasternal short axis view shows trileaflet left AV valve, presence of cleft mitral valve , presence of common AV junction and abnormal position of the papillary muscles in the left ventricle.  Parasternal long-axis view shows discrepancy in left ventricle inflow and outflow measurements  and presence of LVOTO obstruction.  Straddling of left AV valve is defined in the parasternal long-axis view, 

11. Doppler echo Color flow Doppler interrogation  compliments the anatomical investigation by demonstrating the sites of intracardiac shunting and AV regurgitation, as well as defining any obstruction in the LVOT if present.  Pulsed and continuous wave Doppler  is used for quantitative measurements to assess pulmonary artery pressure, severity of left ventricular outflow tract obstruction (LVOTO).  Note:   The quantitative assessment of valvar stenosis is not accurate by Doppler echocardiography when there is large ASD.  So, it is important to evaluate valve anatomy by two-dimensional echocardiography and look especially for  dysplasia, tethering of leaflets and valve orifice. In such cases valve stenosis may manifest after closure of the ASD.

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14. 1. Loss of offsetting of atrioventricular valves. 2. Deficiency of inlet portion of ventricular septum.  3. Presence of common atrioventricular valve fibrous orifice. 4. Abnormal morphology of atrioventricular valve cusps.  5. Abnormal position of papillary muscles. 6. Longer left ventricular outflow and anterior unwedged position of aorta. Echocardiographic findings common to AVSD patients

15. Angiography Catheterization is indicated only when there is strong echo-based evidence of severe pulmonary hypertension. The best known angiographic feature is the Gooseneck malformation. The body of the goose is produced by the abnormal parietal attachment of the left component of the common AV junction.  A large Lt to Rt shunt at atrial level Show significantly high O2 Saturation from RA compared with blood from IVC & SVC  In complete ECD the PASP is at or near to systemic level In partial ECD the PASP is usually <60% of systemic pressure

16. Natural History 1. For patients with complete ECD, heart failure occurs 1 to 2 months after birth and recurrent pneumonia is common.  2. Without surgical intervention, most patients die by the age of 2 to 3 years. 3. In the latter half of the first year of life, the survivors begin to develop pulmonary vascular obstructive disease . These survivors usually die in late childhood or as young adults. 4. Infants with Down syndrome are particularly susceptible to the early development of PVOD during infancy. As a result, surgery should be performed during infancy

17. Pregnancy All women with a history of AVSD should be evaluated when first contemplating pregnancy to ensure that there are no significant residual hemodynamic problems that may complicate their management. Pregnancy usually is well tolerated by women who have had successful repair of AVSD.  In addition, for women with unrepaired partial AVSD, the left-to-right shunt and the left AV valve regurgitation usually are well tolerated during pregnancy.

18. Management

19. Medical management  In small infants with CHF, anticongestive management consisting of digoxin, diuretics, captopril, and so on should be started   Antibiotics and other supportive measures are indicated for pneumonia and other infections.  Antibiotic prophylaxis against SBE is recommended.    No exercise restriction is indicated in case of partial AVSD

20. Surgical management Complete ECD Indications.  The presence of complete ECD indicates the need for surgery because an important hemodynamic derangement is usually present. Most of these infants have CHF that is unresponsive to medical therapy, and some have elevated pulmonary vascular resistance.  Timing 2 to 4 months of age. Early surgical repair is especially important for infants with Down syndrome and complete ECD because of their known tendency to develop early pulmonary vascular obstructive disease.

21. Palliative Banding of the PA in early infancy is no longer recommended unless other associated abnormalities make complete repair a high-risk procedure.  The mortality rate for PA banding may be as high as 15%.  Corrective Given two ventricles of suitable size and no additional defects, closure of the primum ASD and inlet VSD and construction of two separate and competent AV valves are carried out under cardiopulmonary bypass or deep hypothermia, or both. Some surgeons use a single patch to close the ASD and VSD and reconstruction of the left AV valve as a bileaflet valve, whereas others use a two-patch technique ; one patch for the VSD and a second for the ASD.  The left AV valve is allowed to persist as a trileaflet structure.  Mitral valve replacement may become necessary in a few patients. 

22. Partial ECD Indications and Timing.  The presence of a partial AV canal or primum ASD is an indication for surgical repair.  Elective surgery can be performed in asymptomatic children between 2 and 4 years of age.  Surgery can be performed earlier in infants with CHF, failure to thrive, MR, or a common atrium.  Procedure. Under cardiopulmonary bypass, the primum ASD is closed and the cleft mitral and tricuspid valves are reconstructed. 

23. mortality The mortality rate has been 3% to 10%.  The survival rate is the same for patients with and without Down syndrome.  Factors that increase the surgical risk are  young age, severe AV valve regurgitation, hypoplasia of the LV, increased and fixed pulmonary vascular resistance, and severe preoperative symptoms.  Other defects (e.g., double-orifice mitral valve, single left-sided papillary muscle, additional muscular VSD) increase the surgical risk.  The hospital mortality rate for complete ECD and TOF is around 10%.  For partial ECD, The surgical mortality rate is approximately 3%.  Risk factors include the presence of CHF or cyanosis, failure to thrive, and moderate to severe MR. 

24.   Complications  MR becomes persistent or worsens 10% of the time.  Sinus node dysfunction resulting in bradyarrhythmias may occur. Although complete heart block occurs rarely (in <5% of patients), it occurs more frequently when mitral valve replacement is required (up to 20% of patients). Postoperative arrhythmias occur and are usually supraventricular.  Although rare, subaortic stenosis can develop after surgery

25. Postoperative Follow-up An office evaluation should be performed every 6 months to 1 year.  SBE prophylaxis should be continued as indicated, even after surgery.  Medications (e.g., digitalis, diuretics, captopril) may be required if residual hemodynamic abnormalities are present.  Some restriction of activities may be necessary if significant MR or other complications exist.  Rarely, subaortic stenosis may appear after surgical repair of complete ECD (although it is less frequent than in patients who had primum ASD repair), requiring surgical resection.

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