: Echocardiographic Assessment of · PDF file : Echocardiographic Assessment of Atrial Septal...

PTEmasters.com: Echocardiographic Assessment of Atrial Septal Defects

[email protected]

Atrial septal defects (ASDs) are one of the more common congenital lesions

encountered perioperatively both in the adults and children. This review article

describes ASD anatomy and pathophysiology with an emphasis on

echocardiographic assessment of the lesions and their associated problems.

Morphologically, four atrial septal defects exist: ostium secundum,

ostium primum, sinus venosus, and coronary sinus. ASD pathophysiology

involves anatomic and physiologic shunting at the atrial level (1). Physiologic left to

right shunting results in recirculation of oxygenated venous blood into the

pulmonary artery and back into the left atrium (LA). Anatomically this involves

blood flow from the higher-pressure atrium (LA), to the lower pressure right atrium

(RA). Mean RA pressure is normally lower than mean LA pressure because right

ventricular (RV) compliance exceeds left ventricular (LV) compliance. Usually, RV

pressure is less than LV pressure, and pulmonary vascular resistance (PVR) is

usually less than systemic vascular resistance (SVR). The left to right flow through

the defect diminishes effective forward LV flow and results in volume overload of

the RA, RV, and LA(2). Thus, right ventricular volume overload (RVVO) is the

hallmark of large left to right atrial level shunts and is easily detected qualitatively

with transesophageal echocardiography (TEE)(1,3). Leftward shifting of the

interventricular septum during late diastole may be visualized with M-mode

echocardiography and is characteristic of RVVO (2,4). Increased right-sided flow

often results in dilation of the main pulmonary artery (MPA) and increased

pulmonary venous flow. Color flow Doppler (CFD) assists detection of flow across


[email protected]

the interatrial septum. Bidirectional flow indicates elevated RA pressure, which is

the consequence of RV dysfunction, tricuspid regurgitation, and/or impaired

diastolic function. An important cause of these changes is RV hypertension from

the pulmonary vascular remodeling that results from chronic pulmonary

overcirculation due to a left to right shunt. These changes are more likely with a

ratio of pulmonary to systemic flow (Qp/Qs) > 2:1.

Pulsed-wave or continuous-wave Doppler can be used to estimate the mean and

peak pressure gradients between the two atria by the following formula: ∆P = (LAP

– RAP) = 4 (velocity of flow across septum)2, where LAP is the left atrial pressure,

RAP is the right atrial pressure and ∆P is the difference between the two(5).

Ostium Secundum Defects

Ostimum secundum defects occur in the fossa ovalis and are the most

common ASD (75%)(1). During embryologic development a thin pliable septum

primum develops on the left atrial side of a thick muscular septum secundum (fatty

limbus). During formation of these curtain-like septa, two gaps or foramen develop,

the foramen primum and foramen secundum(6). Eventually both foramen close and

the muscular, septum secundum lies on the right atrial side of the thin pliable

septum primum, with the septum primum acting as the flap covering the fossa ovalis.

Secundum ASDs represent a defect in the embryologic septum primum in the area of

the fossa ovalis, which was the original fossa secundum; hence the name ostium

secundum. Secundum ASDs represent a hole in the septum primum and this


[email protected]

distinguishes them from a patent foramen ovale that is simply failure of the septum

primum (the flap of the fossa ovalis) to completely fuse with the septum secundum.

Morphologically four secundum subtypes exist (2):

Virtual absence of the septum primum with the ASD representing the

entire fossa ovalis

Deficiency of a portion of the septum primum (ASD represents part of

the fossa ovalis)

Completely fenestrated septum primum where there are multiple

small defects in the entire septum primum (“Swiss cheese

“appearance of fossa ovalis)

Partially fenestrated septum primum where part of the septum

primum is missing and the remainder is fenestrated

Secundum ASDs are often oval shaped with a 2:1 ratio of the major to minor axis (2).

The longest part of the oval or major axis runs cephalad to caudad from the superior

vena cava (SVC) to inferior vena cava (IVC) as seen in a midesophageal (ME) bicaval

view and usually ranges in size from 4 to 30 mm with a mean of 15 mm. Usually a

tissue remnant or rim exists at both the anteroposterior and inferosuperior borders

but in large defects the rim may be deficient.

Secundum defects are visualized in the ME bicaval view and in a modified ME

aortic valve short axis view between 30 and 60 degrees. The defect is limited to the

fossa ovalis and usually a rim is seen surrounding the defect. (Videos 1 & 3)


[email protected]

In the ME bicaval view the defect is seen clearly in the fossa ovalis and this helps

distinguish it from a superior sinus venosus defect, which lies cephalad (superior) to

the crista terminalis (Figure 1, Videos 1 and 3). Surgical repair of a secundum ASD

often involves a patch with pericardium. Alternatively homograft material or woven

Dacron patch material is utilized. Small defects may be closed primarily. In patients

with a prominent Eustachian valve care must be taken to ensure this is not mistaken

for the inferior end of the ASD. Should this mistake occur, the IVC would be baffled

to the LA creating a right to left shunt, which may be visualized on perioperative

TEE.

Secundum defects often have a surrounding “rim” of septal tissue making

them amenable to closure with percutaneous devices (1,7,8). Percutaneous device

closure of an ASD is a generally safe and effective alternative to open surgical

closure with decreased trauma and shorter hospital length of stay(7). Embolization

following transcatheter ASD device placement is a rare (<2%(8), 0.55%(7) ) but

potentially lethal complication. Other possible problems following transcatheter

ASD device closure include: device erosion (0.1%), residual shunts (<4%), atrial

arrhythmias (<5%), device size mismatch (<5%), cerebral infarcts (rare), infective

endocarditis, and vascular access complications. (8) The ideal ASD for transcatheter

closure is small (<20 mm) with large (>5 mm) firm rims of septal tissue separating

the ASD from the surrounding structures (atrioventricular valves, superior and

inferior vena cavae, right upper pulmonary vein, coronary sinus). Very large ASDs

(>40mm) have been closed with devices, but the catastrophic risk of erosion

http://www.google.com/search?hl=en&client=safari&rls=en&sa=X&ei=BjUaTovnA4bZgAfrq4Al&ved=0CBsQvwUoAQ&q=eustachian+valve&spell=1


[email protected]

(cardiac perforation) increases as device size increases(8). Although the mechanism

for erosion is not fully understood, the only known independent risk factor from a

survey of all reported erosions was an oversized device (8). Device embolization can

cause significant ventricular arrhythmias, obstruction to flow, and valvular

insufficiency. Although percutaneous retrieval of stray devices has been reported

(9,10), many consider this a cardiac surgical emergency. TEE is useful for

determining the location of the stray device, detecting associated pathology (such as

LVOT obstruction) and ensuring appropriate ASD closure and de-airing postbypass.

Sinus Venous Defects

Sinus venosus ASDs are located near either the SVC (superior defects) or IVC

(inferior defects) entrance into the RA (Video 3, figure 1). Superior defects are much

more common than inferior defects which are rare. Sinus venosus defects are often

associated with partially anomalous pulmonary venous connections. The distinction

between an anomalous connection (drainage of a pulmonary vein into a structure

other than the LA) and anomalous drainage (drainage of normally positioned

pulmonary veins across the defect into the SVC/RA junction or IVC/RA junction)

must be made.

Both superior and inferior defects are located posterior to the fossa ovalis.

Strictly speaking these are not defects in the true atrial septum. These defects are

believed to result from a deficiency in the common wall, which normally separates

the pulmonary veins from the RA and the SVC rather than a defect in the atrial

septum or a change in the position of the pulmonary veins. Unroofing of the

posteriorly located pulmonary vein(s) produces drainage of the LA into the SVC and


[email protected]

RA creating a left to right shunt. The interatrial communication is an orifice of the

pulmonary veins rather than a defect in the atrial septum. The most common type of

anomalous pulmonary connection is the right upper pulmonary vein (RUPV)

draining directly into the lateral wall of the SVC above the SVC/RA junction at the

level of the right pulmonary artery (figure 2, video 3).

Imaging superior sinus venosus defects is facilitated by multiplane TEE,

which is superior to transthoracic echocardiography for visualizing this lesion(1,2).

In the ME bicaval view, the superior aspect of a superior sinus venosus defect

appears to be the right pulmonary artery due to the absence of the fatty limbus just

posterior to the orifice of the SVC (fig 2, video 3). If pulmonary veins are normally

positioned the defect may be closed with a pericardial patch. If the pulmonary veins

enter the SVC anomalously, then a Warden procedure may be performed(11,12).

With the Warden procedure the SVC is transected above the origin of the anomalous

vein(s), the proximal end of the SVC is oversewn and the orifice of the SVC is baffled

into the LA with a pericardial patch. The distal end of the SVC is then anastomosed

end-to-end to the roof of the RA appendage (RAA)(Figure 3)(11,12).

Ostium Primum Defects (figure 4, Videos 2 and 4)

Ostium primum ASDs often occur in conjunction with a common

atrioventricular valve orifice. Primum defects are associated with inlet ventricular

septal defects (VSD), and cleft atrioventricular (AV) valve leaflets. These lesions are

commonly seen in patients with trisomy 21. Primum defects result from a defect in

the endocardial cushions. A primum ASD with no associated VSD is a partial AV


[email protected]

canal. A primum ASD plus a restrictive inlet VSD constitutes a transitional AV canal,

and a primum ASD plus a nonrestrictive inlet VSD constitutes a complete AV canal

(CAVC) detect. The ostium primum defect lies posterior and inferior to the fossa

ovalis near the AV valves. A characteristic finding of this lesion is insertion of the

septal portions of both atrioventricular valves to the IVS at the same level. Normally

insertion of the tricuspid valve (TV) to the IVS is inferior (more apical) to that of the

mitral valve (MV), producing a ventriculoatrial septum, which separates the RA

from the LV. As a consequence, with primum ASDs and atrioventricular (AV) canal

defects the valves appear in the same plane and the defect is very close to these

valves (Figure 4). Close proximity to the AV valve leaflets helps explain the

association of cleft septal tricuspid and anterior mitral valve (MV) leaflets. The cleft

anterior MV leaflet is the result of partial fusion of the antero-superior and infero-

posterior bridging leaflets, which normally fuse to form the anterior MV leaflet.

Occasionally the posterior MV leaflet has a cleft or both mitral valve leaflets contain

clefts(13-15). These clefts cause mitral insufficiency and complicate repair of this

lesion. The ME 4-chamber view will reveal a defect in the posterior-inferior aspect

of the interatrial septum extending to the junction of the AV valves (figure 4). The

cleft MV can be appreciated as discontinuity of the anterior MV leaflet in any of the

short or long axis views, which optimize imaging of this leaflet. Three-dimensional

echocardiography of an en face view of the mitral valve and/or the transgastric

basal short axis view assist identification of the mitral valve cleft(s) (13-15). Color

flow Doppler imaging can be used to assess the severity of the associated

insufficiency by measuring the width of the vena contracta, and jet area as described


[email protected]

by Zoghbi WA et al (16). Repair usually requires patch closure of the primum ASD

and repair of the cleft AV valve leaflet(s). This mitral repair is normally done with a

few interrupted sutures to create continuity of the mitral leaflet(s). Occasionally

primum ASDs may be closed with transcatheter devices (video 2), but this is often

not feasible due to the proximity of this lesion to the AV valves.

Coronary Sinus Defects

Coronary sinus ASDs result from an unroofing of the posterior aspect of the

coronary sinus (CS) such that LA blood drains into the CS and through the orifice of

the CS into the RA creating a left to right shunt. Coronary sinus ASDs are usually

associated with a persistent left SVC and a large dilated coronary sinus (Figure 5

and Video 1). A persistent left SVC is easily detected with transverse plane imaging

in a modified view between the ME four-chamber view and the transgastric basal

short axis view. The probe is advanced posteriorly or retroflexed and a dilated

coronary sinus becomes visible (figure 5). From the mid esophagus (ME), the

persistent left SVC can be seen between the LA appendage and the left upper

pulmonary vein. A persistent left SVC can be diagnosed with a contrast study with

saline contrast injected into the left arm. With a persistent left SVC the contrast will

be seen entering the coronary sinus prior to the right atrium (video 4). In the ME

two-chamber view and/or ME long axis view, the coronary sinus is seen in short-

axis as an echolucent circle on the post aspect of the LA and communication

between the dilated CS and the LA may be detected (17,18). If a persistent left SVC is

present, repair requires patch closure of the unroofed coronary sinus, which directs


[email protected]

left SVC flow into to RA. In the absence of a left SVC, the orifice of the coronary sinus

may be oversewn resulting in closure of the LA to RA communication while leaving a

very small (<5%) right to left coronary sinus to LA shunt (12). As shown by Joffe et

al. (18) the ME 2-chamber view often nicely illustrates the communication of the

coronary sinus with the left atrium.

A patent foramen ovale (PFO), the most common defect in the interatrial

septum, occurs in 25% of the population (19,20) (Figure 6, Video 1). This may be

distinguished from an ostium secundum ASD by the presence of a flap. A secundum

represents a hole in the septum primum whereas a PFO represents failure of the

septum primum to completely fuse with the septum secundum.

Transesophageal echocardiography (TEE) assists in PFO detection (19,20).

Every comprehensive TEE examination should include interrogation of the

interatrial septum for a PFO with color flow Doppler and, if necessary, contrast

echocardiography. Color flow Doppler examination of the septum should be

performed in multiple views, with the color flow Doppler scale decreased to 20-40

cm/s since flow across the septum is low velocity. If color flow Doppler is negative,

or inconclusive and ruling out a PFO essential (for example in a patient undergoing

left ventricular assist device placement), then a contrast exam should be performed.

Agitated saline may function as echo contrast and it should be injected

intravenously while imaging the septum. In ventilated patients, this is performed

with and without the release of 20 -30 cm H2O positive airway pressure. The release

of positive airway pressure provokes a transient increase in right atrial pressure,

(increasing RAP >LAP) which forces the contrast medium against the septum and


[email protected]

across the defect, if present. Visualization of contrast medium crossing into the left

atrium within 3-5 cardiac cycles is consistent with a positive contrast study (20). An

agitated saline contrast study with release of positive pressure (as described above)

significantly improves PFO detection and should be conducted if color flow Doppler

examination is negative and ruling out a septal defect is essential (20). Release of a

Valsalva maneuver results in similar findings in non-ventilated patients and is often

used with transthoracic echocardiography. Of note, absence of leftward bulging of

the interatrial septum during opacification of the right atrium with saline contrast

was the most frequent characteristic of a false-negative injection (21).

A patent foramen ovale is associated with a Chiari network and aneurysmal

interatrial septum. The prevalence of an aneurysmal interatrial septum is 1%-2.2%

and they are associated with a PFO in 50%-89% of patients (19). Patients with an

aneurysmal interatrial septum and a PFO are at high-risk for paradoxical cerebral

embolus (3-5 times higher risk than patients with a PFO alone) (22-24) . Although

there is a good study showing that an incidental PFO probably should not be

repaired during cardiac surgery (25), patients with an aneurysmal interatrial

septum may still benefit because they are at very high risk for paradoxical cerebral

embolus(22-24).

Conclusion:

Periprocedure echocardiography assists in confirmation of the diagnosis,

placement of catheter closure devices and postoperative assessment of adequate


[email protected]

surgical or device closure. Echocardiography continues to improve and evolve,

enhancing our understanding of these lesions in children and adults.

Figure 1

Figure 1 shows a comparison of an ostium secundum ASD and a superior sinus venosus

ASD seen in a bicaval view. LA = left atrium, RA = right atrium, ME = midesophageal,

Sec ASD = ostium secundum ASD, SV ASD = sinus venosus ASD, ASD = atrial septal

defect.


[email protected]

Figure 2

Figure 2 shows a ME Bicaval view showing a superior sinus venosus ASD. LA = left

atrium, RA = right atrium, ME = midesophageal, RPA = right pulmonary artery, RUPV =

right upper pulmonary vein.


[email protected]

Figure 3

Figure 3 shows the surgical approach for a Warden procedure. With the Warden procedure the SVC is transected above the origin of the anomalous vein(s), the proximal end of the SVC is oversewn and the orifice of the SVC is baffled into the LA with a pericardial patch. The distal end of the SVC is then anastomosed end-to-end to the roof of the RA appendage (RAA). RUPV = right upper pulmonary vein, SVC = superior vena cava, RAA = right atrial appendage, RA = right atrium, RV = right ventricle, LA = left atrium, LV = left ventricle B = area above incision, anastomosed to the right atrial appendage. A = area below incision.


[email protected]

Figure 4 shows an ostium primum ASD in a midesophageal four chamber view. RA = right atrium, LA = left atrium, RV = right ventricle, LV = left ventricle, ASD = atrial septal defect.

Figure 5 Figure 5 shows a dilated coronary sinus (CS) in a patient with a persistent left superior vena cava. RA = right atrium, RV = right ventricle, LV = left ventricle.


[email protected]

Figure 6 Figure 6 shows a patent foramen ovale (PFO). RA = right atrium, LA = left atrium, ASD = atrial septal defect.

References:

1. Russell IA, Rouine-Rapp K, Stratmann G, Miller-Hance WC. Congenital heart disease in the adult: a review with internet-accessible transesophageal echocardiographic images. Anesth Analg 2006;102:694-723.

2. DiNardo JA ZD. Anesthesia for Cardiac surgery. Third ed. Oxford, UK: Blackwell Publishing, 2008.

3. Lang RM, Bierig M, Devereux RB, Flachskampf FA, Foster E, Pellikka PA, Picard MH, Roman MJ, Seward J, Shanewise JS, Solomon SD, Spencer KT, Sutton MS, Stewart WJ. Recommendations for chamber quantification: a report from the American Society of Echocardiography's Guidelines and Standards Committee and the Chamber Quantification Writing Group, developed in conjunction with the European Association of Echocardiography, a branch of the European Society of Cardiology. J Am Soc Echocardiogr 2005;18:1440-63.

4. Rudski LG, Lai WW, Afilalo J, Hua L, Handschumacher MD, Chandrasekaran K, Solomon SD, Louie EK, Schiller NB. Guidelines for the echocardiographic assessment of the right heart in adults: a report from the American Society of Echocardiography endorsed by the European Association of Echocardiography, a registered branch of the European Society of Cardiology, and the Canadian Society of Echocardiography. J Am Soc Echocardiogr;23:685-713; quiz 86-8.


[email protected]

5. Quinones MA, Otto CM, Stoddard M, Waggoner A, Zoghbi WA. Recommendations for quantification of Doppler echocardiography: a report from the Doppler Quantification Task Force of the Nomenclature and Standards Committee of the American Society of Echocardiography. J Am Soc Echocardiogr 2002;15:167-84.

6. Moore K. The Developing Human. Fith ed.: W. B. Saunders Company, 1993. 7. Knirsch W, Dodge-Khatami A, Valsangiacomo-Buechel E, Weiss M, Berger F.

Challenges encountered during closure of atrial septal defects. Pediatr Cardiol 2005;26:147-53.

8. Kim MS, Klein AJ, Carroll JD. Transcatheter closure of intracardiac defects in adults. J Interv Cardiol 2007;20:524-45.

9. Chan KT, Cheng BC. Retrieval of an embolized amplatzer septal occluder. Catheter Cardiovasc Interv;75:465-8.

10. Lerakis S, Babaliaros V, Junahadhwalla Z, Williams SK, Martin R. Three-dimensional transesophageal echocardiographic guidance during retrieval of an embolized percutaneous atrial septal defect closure device. Echocardiography 2009;26:970-2.

11. DiBardino DJ, McKenzie ED, Heinle JS, Su JT, Fraser CD, Jr. The Warden procedure for partially anomalous pulmonary venous connection to the superior caval vein. Cardiol Young 2004;14:64-7.

12. Jonas R. Comprehensive Surgical Management of Congenital Heart Disease: Hodder Arnold, 2004.

13. Muller H, Kalangos A, Fassa AA, Lerch R. Isolated cleft mitral valve with posterior and anterior clefts: a rare cause of congenital valve regurgitation. Echocardiography;27:E50-2.

14. Muller H, Cikirikcioglu M, Lerch R. Isolated posterior mitral valve cleft: diagnosis by real-time three-dimensional transoesophageal echocardiography. Eur J Echocardiogr;11:E29.

15. Townsley MM, Chen EP, Sniecinski RM. Cleft posterior mitral valve leaflet: identification using three-dimensional transesophageal echocardiography. Anesth Analg;111:1366-8.

16. Zoghbi WA, Enriquez-Sarano M, Foster E, Grayburn PA, Kraft CD, Levine RA, Nihoyannopoulos P, Otto CM, Quinones MA, Rakowski H, Stewart WJ, Waggoner A, Weissman NJ. Recommendations for evaluation of the severity of native valvular regurgitation with two-dimensional and Doppler echocardiography. J Am Soc Echocardiogr 2003;16:777-802.

17. Roberson DA, Cui W, Patel D, Tsang W, Sugeng L, Weinert L, Bharati S, Lang RM. Three-dimensional transesophageal echocardiography of atrial septal defect: a qualitative and quantitative anatomic study. J Am Soc Echocardiogr;24:600-10.

18. Joffe DC, Rivo J, Oxorn DC. Coronary sinus atrial septal defect. Anesth Analg 2008;107:1163-5.

19. Burch TM, Davidson MF, Pereira SJ. Use of transesophageal echocardiography in the evaluation and surgical treatment of a patient with an aneurysmal interatrial septum and an intracardiac thrombus traversing a patent foramen ovale. Anesth Analg 2008;106:769-70.


[email protected]

20. Augoustides JG, Weiss SJ, Weiner J, Mancini J, Savino JS, Cheung AT. Diagnosis of patent foramen ovale with multiplane transesophageal echocardiography in adult cardiac surgical patients. J Cardiothorac Vasc Anesth 2004;18:725-30.

21. Johansson MC, Eriksson P, Guron CW, Dellborg M. Pitfalls in diagnosing PFO: characteristics of false-negative contrast injections during transesophageal echocardiography in patients with patent foramen ovales. J Am Soc Echocardiogr;23:1136-42.

22. Agmon Y, Khandheria BK, Meissner I, Gentile F, Whisnant JP, Sicks JD, O'Fallon WM, Covalt JL, Wiebers DO, Seward JB. Frequency of atrial septal aneurysms in patients with cerebral ischemic events. Circulation 1999;99:1942-4.

23. Mas JL, Arquizan C, Lamy C, Zuber M, Cabanes L, Derumeaux G, Coste J. Recurrent cerebrovascular events associated with patent foramen ovale, atrial septal aneurysm, or both. N Engl J Med 2001;345:1740-6.

24. Pearson AC, Nagelhout D, Castello R, Gomez CR, Labovitz AJ. Atrial septal aneurysm and stroke: a transesophageal echocardiographic study. J Am Coll Cardiol 1991;18:1223-9.

25. Krasuski RA, Hart SA, Allen D, Qureshi A, Pettersson G, Houghtaling PL, Batizy LH, Blackstone E. Prevalence and repair of intraoperatively diagnosed patent foramen ovale and association with perioperative outcomes and long-term survival. JAMA 2009;302:290-7.

: Echocardiographic Assessment of · PDF file : Echocardiographic Assessment of Atrial Septal...

Documents

Transcript of : Echocardiographic Assessment of · PDF file : Echocardiographic Assessment of Atrial Septal...