Damus-Kaye-Stansel Procedure #1–3: Concept and Anastomotic Strategies

The Damus-Kaye-Stansel (DKS) procedure creates a direct communication between the pulmonary root and the systemic arterial pathway, allowing the pulmonary root to function as an additional systemic ventricular outlet. In congenital heart surgery, its principal application is the treatment or prevention of systemic ventricular outflow tract obstruction (SVOTO) in patients undergoing single-ventricle palliation. The central objective is not simply to enlarge an existing obstruction, but to establish a durable, low-resistance alternative pathway from the systemic ventricle to the ascending aorta while preserving semilunar-valve function [1].

Two major reconstructive configurations are used:

1. Side-to-end DKS, more commonly described as end-to-side DKS in the surgical literature, in which the transected proximal main pulmonary artery is anastomosed to the side of the ascending aorta.
2. Double-barrel DKS, in which the aortic and pulmonary roots are joined laterally and incorporated into a common systemic outflow.

Both techniques can effectively eliminate SVOTO. However, their effects on pulmonary-root geometry and semilunar-valve function differ, making the three-dimensional relationship of the great arteries an important determinant of surgical strategy.

1. Why Systemic Ventricular Outflow Obstruction Develops

SVOTO is particularly important when the dominant systemic ventricle does not have a direct, unrestricted connection to the aorta. Typical substrates include:

• Double-inlet left ventricle with transposed great arteries
• Tricuspid atresia with transposed great arteries
• Selected double-outlet right ventricle configurations undergoing single-ventricle palliation
• Other univentricular anatomies in which systemic blood must traverse a ventricular communication or outlet chamber before reaching the aortic root

In these configurations, systemic ventricular ejection may follow the pathway:

Systemic ventricle → bulboventricular foramen or ventricular septal communication → outlet chamber → aortic valve → ascending aorta

The ventricular communication may initially appear adequate but become relatively restrictive with growth or after staged palliation. Previous pulmonary artery banding is an important setting because ventricular hypertrophy and geometric remodeling can further reduce the effective subaortic pathway. Arch obstruction may coexist and compound systemic outflow resistance [2,3].

Importantly, obstruction is not necessarily static. Reduction in ventricular volume after a bidirectional Glenn can alter septal and ventricular geometry and expose a previously compensated subaortic narrowing. Consequently, the absence of a significant preoperative Doppler gradient does not necessarily imply that the future systemic outlet is secure.

2. Physiologic Principle of DKS Reconstruction

The DKS procedure bypasses the vulnerable intraventricular systemic outlet by providing an alternative route:

Systemic ventricle → pulmonary valve → pulmonary root → DKS connection → ascending aorta

The native aortic pathway remains present, but systemic ventricular output can now reach the ascending aorta through two potential routes. The pulmonary root effectively becomes a parallel systemic outlet.

This concept is particularly important because simply enlarging a bulboventricular foramen or performing direct subaortic resection may not provide durable relief when the underlying geometry remains unfavorable. DKS reconstruction relocates the critical systemic pathway away from the restrictive intracardiac segment.

The physiologic goals are therefore to:

• Minimize systemic ventricular afterload
• Prevent progressive ventricular hypertrophy
• Preserve ventricular systolic and diastolic performance
• Limit secondary atrioventricular valve regurgitation
• Provide a durable systemic outlet throughout subsequent staged palliation

Early experiences combining DKS with cavopulmonary connection demonstrated that this approach could eliminate residual systemic obstruction in selected high-risk single-ventricle patients [2].

3. Timing: Treatment Versus Prophylaxis

DKS may be performed either for established SVOTO or prophylactically before a clinically important gradient develops.

Historically, intervention was often triggered by documented subaortic obstruction. However, contemporary experience supports earlier reconstruction in anatomies strongly predisposed to obstruction, particularly at the time of bidirectional Glenn.

In a series of 25 patients undergoing prophylactic DKS concomitant with bidirectional Glenn, systemic outflow gradients remained very low during follow-up, and 84% subsequently completed Fontan circulation [4]. Similarly, a 36-patient series of DKS performed during cavopulmonary connection reported elimination of follow-up systemic outflow gradients, with zero or trivial semilunar regurgitation in 78% of patients [5].

These observations support a key surgical principle:

When the anatomy predicts progressive SVOTO, prevention may be preferable to waiting for a measurable high-gradient lesion.

The decision should therefore incorporate:

• Size of the bulboventricular foramen or ventricular communication
• Relationship between the dominant ventricle and outlet chamber
• Degree of ventricular hypertrophy
• Previous pulmonary artery banding
• Associated arch obstruction
• Great-artery relationship
• Expected geometric changes after ventricular volume unloading
• Ventricular and atrioventricular valve function

DKS may also be performed at Fontan completion when obstruction becomes apparent later. In Fontan patients with established systemic outflow obstruction, DKS has provided effective midterm relief with generally low postoperative gradients [6].

Damus-Kaye-Stansel Procedure #2: Side-to-End DKS Anastomosis

4. Basic Construction

In the side-to-end technique, the main pulmonary artery is transected above the pulmonary valve, and the proximal pulmonary trunk is anastomosed to an opening in the lateral ascending aorta.

In anatomic terms, the pulmonary end is connected to the aortic side; consequently, this configuration is usually called end-to-side DKS in published surgical series.

The reconstruction redirects ventricular ejection through the pulmonary valve directly into the ascending aorta, thereby bypassing the restrictive subaortic pathway.

The conceptual operative sequence is:

1. Mobilize the ascending aorta and main pulmonary artery.
2. Transect the main pulmonary artery above the pulmonary root.
3. Create an appropriately positioned opening in the ascending aorta.
4. Approximate the pulmonary root to the ascending aorta without tension.
5. Complete a wide pulmonary-to-aortic anastomosis.
6. Add flap or patch augmentation when necessary to improve geometry or accommodate size discrepancy.

The objective is not merely a technically patent connection but a smooth, nonrestrictive systemic flow pathway.

5. Importance of Great-Artery Relationship

The spatial relationship of the aorta and pulmonary artery strongly influences DKS geometry.

The great arteries may be:

• Anterior-posterior
• Obliquely related
• Nearly side-by-side
• Discrepant in diameter

A side-to-end reconstruction is particularly useful when direct approximation can be achieved without excessive rotation. In more lateral or side-by-side configurations, an aortic flap or patch augmentation may help construct a wider transition and avoid tension.

The anastomosis should be sufficiently large to prevent a new supravalvar obstruction, but excessive mobilization or forced approximation can distort the semilunar root.

Thus, anastomotic size and root geometry must be considered simultaneously.

6. Pulmonary-Root Distortion and Valve Function

The major concern with an asymmetric side-to-end reconstruction is distortion of the pulmonary root.

The pulmonary root is a three-dimensional functional structure composed of:

• The annulus
• Semilunar leaflets
• Commissures
• Sinuses
• Sinotubular junction

After DKS, the pulmonary valve becomes part of the systemic outlet and is exposed to systemic pressure. Preservation of pulmonary sinus and commissural geometry therefore becomes particularly important.

Retrospective comparative data suggest that end-to-side reconstruction may produce more pulmonary-valve regurgitation than double-barrel DKS. In a 47-patient series, pulmonary regurgitation occurred in 4 of 11 end-to-side patients compared with 1 of 34 double-barrel patients [7]. The proposed mechanism was deformation of the pulmonary sinus resulting from asymmetric traction on the pulmonary root.

This finding illustrates an important technical distinction: a DKS anastomosis may be widely patent yet still be suboptimal if it compromises semilunar-valve geometry.

Damus-Kaye-Stansel Procedure #3: Double-Barrel DKS Anastomosis

7. Concept of the Double-Barrel Reconstruction

The double-barrel DKS creates a broader and more symmetric common systemic outlet.

Both great arteries are transected above their semilunar valves. Adjacent portions of the proximal aortic and pulmonary roots are opened and joined laterally. The resulting bivalved proximal outflow is then incorporated into the reconstructed ascending systemic artery.

The final pathway consists of:

• Native aortic root
• Pulmonary root
• Broad communication between the two roots
• Common distal systemic outflow into the ascending aorta

Rather than directing the pulmonary root obliquely toward the aorta, the two roots remain adjacent and function as parallel outlets.

8. Preservation of Semilunar-Root Geometry

The principal theoretical advantage of the double-barrel technique is better preservation of pulmonary sinus geometry.

Because the pulmonary and aortic roots are joined along their adjacent walls, the pulmonary root is subjected to less asymmetric lateral traction than in an end-to-side construction. This may allow more physiologic preservation of:

• Commissural orientation
• Sinus configuration
• Sinotubular geometry
• Leaflet coaptation

The comparative series by Fujii and colleagues found significantly less pulmonary regurgitation after double-barrel reconstruction, supporting the importance of maintaining pulmonary sinus shape [7].

A separate retrospective series in which operative technique was selected according to great-artery anatomy reported no recurrent SVOTO during follow-up. Double-barrel DKS was favored for an anterior-posterior great-artery relationship, whereas an ascending-aortic-flap side-to-end technique was used for side-by-side arteries. One side-to-end patient ultimately required neoaortic valve replacement for regurgitation [8].

These data are limited by small sample size and nonrandomized technique selection, but they reinforce the principle that DKS configuration should be tailored to the native three-dimensional anatomy.

9. Patch Augmentation

Size discrepancy between the native aorta and pulmonary root can make reconstruction difficult. Patch augmentation may therefore be incorporated into either DKS configuration.

In the double-barrel technique, augmentation of the distal ascending aorta can create a broad transition from the combined roots into the systemic artery. Modified double-barrel techniques have specifically incorporated anterior patch augmentation to avoid narrowing while preserving semilunar-root geometry [9].

Patch design should avoid:

• Acute angulation
• Localized supravalvar narrowing
• Excessive widening that distorts either root
• Tension on the commissures
• Distortion of the coronary-bearing aortic root

The surgeon should therefore conceptualize the reconstruction as a three-dimensional systemic root complex, rather than simply as an anastomosis between two vessels.

10. Side-to-End Versus Double-Barrel DKS

Side-to-End / End-to-Side DKS

Potential advantages include:

• Direct construction
• Flexibility in positioning the proximal pulmonary artery
• Limited reconstruction of the native aortic root
• Ability to use an aortic flap or patch when necessary

Potential concerns include:

• Asymmetric pulmonary-root traction
• Pulmonary sinus deformation
• Semilunar regurgitation
• Local narrowing if the connection is small or angulated

Double-Barrel DKS

Potential advantages include:

• Broad systemic outlet
• Symmetric incorporation of both semilunar roots
• Better preservation of pulmonary sinus geometry
• Lower observed pulmonary-regurgitation rates in small retrospective comparative series [7]

Potential concerns include:

• More extensive great-artery reconstruction
• Need for precise root alignment
• Patch augmentation when substantial size discrepancy exists
• Potential distortion of either root if reconstruction is asymmetric

Neither technique should be considered universally superior for every patient. Great-artery relationship, root dimensions, previous operations, arch anatomy, coronary relationships, and the planned stage of palliation must all be considered.

11. Intraoperative Assessment

After DKS reconstruction, assessment should address both systemic outflow adequacy and semilunar-valve competence.

Echocardiographic assessment should include:

• Flow through the DKS connection
• Residual systemic outflow gradient
• Pulmonary/neo-aortic valve regurgitation
• Native aortic valve regurgitation
• Ventricular systolic function
• Atrioventricular valve regurgitation

The reconstructed pathway should demonstrate smooth flow without significant acceleration. Particular attention should be directed to newly developed pulmonary-valve regurgitation because it may indicate distortion of the pulmonary root rather than intrinsic leaflet disease.

12. Long-Term Surveillance

Published series consistently demonstrate that DKS is effective in preventing recurrent systemic outflow obstruction when performed appropriately, including when used prophylactically at the cavopulmonary stage [4-6]. However, the available evidence consists predominantly of small retrospective cohorts.

Long-term surveillance should evaluate:

• Recurrent systemic outflow obstruction
• DKS anastomotic narrowing
• Pulmonary/neo-aortic regurgitation
• Native aortic valve regurgitation
• Root dilatation
• Ventricular hypertrophy
• Ventricular systolic and diastolic function
• Atrioventricular valve competence
• Subsequent Fontan candidacy and completion

Current evidence is strongest for the ability of DKS to provide durable relief of SVOTO. Evidence regarding very long-term ventricular remodeling, root dilatation, and comparative valve outcomes remains more limited.

13. Surgical Perspective

The fundamental principle of DKS is to secure systemic ventricular egress before obstruction produces irreversible physiologic consequences.

A successful reconstruction must accomplish three objectives:

1. Create a wide, low-resistance systemic outlet.
2. Preserve semilunar-root and valve geometry.
3. Integrate the reconstruction into the staged single-ventricle pathway.

Prophylactic DKS at the time of bidirectional Glenn is particularly valuable when anatomy predicts progressive SVOTO, even when a substantial resting gradient has not yet developed [4,5].

The side-to-end technique can provide excellent relief of obstruction, particularly when great-artery geometry permits a tension-free connection. The double-barrel technique creates a more symmetric common outlet and appears to better preserve pulmonary-valve function by reducing sinus distortion [7].

Ultimately, the optimal DKS is not simply the largest anastomosis. It is the reconstruction that provides a durable systemic pathway while maintaining the geometry and competence of both semilunar roots throughout the patient's staged single-ventricle circulation.

References

[1] Fraser CD. Management of systemic outlet obstruction in patients undergoing single ventricle palliation. Semin Thorac Cardiovasc Surg Pediatr Card Surg Annu. 2009. doi:10.1053/j.pcsu.2009.01.006.

[2] Huddleston CB, Canter CE, Spray TL. Damus-Kaye-Stansel with cavopulmonary connection for single ventricle and subaortic obstruction. Ann Thorac Surg. 1993. doi:10.1016/0003-4975(93)90994-S.

[3] McElhinney DB, Reddy VM, Silverman NH, Hanley FL. Modified Damus-Kaye-Stansel procedure for single ventricle, subaortic stenosis, and arch obstruction in neonates and infants: midterm results and techniques for avoiding circulatory arrest. J Thorac Cardiovasc Surg. 1997. doi:10.1016/S0022-5223(97)70075-8.

[4] Shimada M, Hoashi T, Kagisaki K, Shiraishi I, Yagihara T, Ichikawa H. Clinical outcomes of prophylactic Damus-Kaye-Stansel anastomosis concomitant with bidirectional Glenn procedure. J Thorac Cardiovasc Surg. 2012. doi:10.1016/j.jtcvs.2011.09.009.

[5] Alsoufi B, Alwadai A, Khan M, Al-Ahmadi M, Kalloghlian A, Bulbul Z, Alfayyadh M, Al-Halees Z. Outcomes of Damus-Kaye-Stansel anastomosis at time of cavopulmonary connection in single ventricle patients at risk of developing systemic ventricular outflow tract obstruction. Eur J Cardiothorac Surg. 2014. doi:10.1093/ejcts/ezt251.

[6] Hiramatsu T, Imai Y, Kurosawa H, Takanashi Y, Aoki M, Shinoka T, Sakamoto T. Midterm results of surgical treatment of systemic ventricular outflow obstruction in Fontan patients. Ann Thorac Surg. 2002. doi:10.1016/S0003-4975(01)03440-3.

[7] Fujii Y, Kasahara S, Kotani Y, Takagaki M, Arai S, Otsuki S, Sano S. Double-barrel Damus-Kaye-Stansel operation is better than end-to-side Damus-Kaye-Stansel operation for preserving the pulmonary valve function: the importance of preserving the shape of the pulmonary sinus. J Thorac Cardiovasc Surg. 2011. doi:10.1016/j.jtcvs.2010.06.007.

[8] Yang CK, Jang W, Choi ES, Cho S, Choi K, Nam J, Kim W. The clinical outcomes of Damus-Kaye-Stansel procedure according to surgical technique. Korean J Thorac Cardiovasc Surg. 2014. doi:10.5090/kjtcs.2014.47.4.344.

[9] Rosenblum JM, Anvari F, Alsoufi B. The Damus-Kaye-Stansel operation: management of systemic ventricular outflow tract obstruction. Multimed Man Cardiothorac Surg. 2018. doi:10.1510/mmcts.2018.017.