Konno-Rastan Aortic Root Enlargement

Anatomy and Physiology

The left ventricular outflow tract (LVOT) comprises 3 distinct regions: subvalvular, valvular, and supravalvular.

Subvalvular Region

The subvalvular region is bordered anteriorly by the muscular and membranous portions of the interventricular septum and posteriorly by the base of the anterior mitral valve leaflet. The valvular region consists of the aortic root, which includes the 3 sinuses of Valsalva, the 3 semilunar aortic valve cusps, attachment to the aortic wall, and the sinotubular junction.

Supravalvular Region

The supravalvar region is formed by the ascending aorta above the sinotubular junction.

Valvar Region

The aortic valve has 3 cusps—right, left, and noncoronary—attached to the aortic wall in a semilunar fashion, forming three commissures at the apex of attachment. The right coronary artery originates from the right sinus of Valsalva. In contrast, the left coronary artery arises from the left sinus of Valsalva, typically in a central position within the sinus. The right ventricular outflow tract (RVOT) is positioned anterior to the subvalvar and valvar regions of the aorta and is bordered posteriorly by the conal muscular septum and anteriorly by the muscular free wall of the right ventricle. Notably, anterior enlargement of the aortic root does not compromise RV outflow, as the anterior free wall of the RV can be expanded using a patch without restrictions.

In Konno-Rastan aortic root enlargement, a longitudinal incision is made in the right coronary sinus, medial to the origin of the right coronary artery. This incision extends inferiorly through the right ventricular outflow tract muscle and the muscular conal septum beneath the right sinus of Valsalva. This technique increases the aortic root diameter and expands the subvalvar LVOT, effectively relieving obstruction and significantly reducing the pressure gradient. The resultant left ventricular remodeling is beneficial for long-term function. Proper closure of the septal defect and reconstruction of the RVOT are crucial to achieving optimal outcomes. Additionally, this approach can be combined with posterior root enlargement procedures for cases with a highly narrow aortic root.

Indications

Indications for the Konno-Rastan Procedure 

The Konno-Rastan procedure is primarily indicated for patients requiring aortic root enlargement to facilitate aortic valve replacement (AVR) and prevent patient-prosthesis mismatch (PPM). The most common indications include the following:

• Aortic root enlargement for AVR

  • To prevent patient-prosthesis mismatch in cases of a small aortic root, particularly in adults undergoing aortic valve replacement
  • In pediatric patients with a small aortic root requiring AVR

• Complex left ventricular outflow tract obstruction

  • Patients with multilevel LVOT obstruction (subvalvar, valvar, and supravalvar) in conjunction with a small aortic root require AVR and obstruction relief
  • In cases of recurrent LVOT obstruction associated with aortic valve disease, AVR and subvalvular LVOT resection are necessary

• Hypertrophic cardiomyopathy 

  • For patients with hypertrophic cardiomyopathy and LVOT obstruction requiring AVR

• Congenital heart defects with aortic stenosis

  • In patients with atrioventricular canal defects complicated by subaortic and aortic stenosis undergoing AVR
  • In individuals with a history of ventricular septal defect (VSD) closure and subvalvar aortic stenosis (modified Konno incision with septal and RVOT patch closure is required)

• Adjunct to other aortic root enlargement procedures

  • Performed in conjunction with other root-enlarging techniques to maximize aortic root expansion
  • Utilized during the Ross procedure to enlarge the aortic annulus and subvalvar region [1]

Personnel

The standard Konno-Rastan requires a surgeon with expertise in the procedure and a trained team, including the following:

• Cardiac surgeon
• Surgeon assistant
• Perfusionist
• Cardiac anesthesia team
• Operating room nursing staff
• Cardiologist

Preparation

Preoperative preparation includes a well-delineated transthoracic or transoesophageal echocardiogram to define the dimensions of the left ventricular outflow tract. The size of the required aortic prosthesis is determined based on the patient’s body surface area, and the effective orifice area of the prosthesis is decided to be used. A computed tomogram or magnetic resonance imaging of the left ventricular outflow tract and aortic valve can help identify the levels of obstruction. Preparing for cardiac surgery includes debriefing the team on the operative plan and preparing the materials. Prosthetic valves and valve sizers are made available along with glutaraldehyde to treat the pericardium, bovine pericardium patch, or dacron patch as planned.

Technique or Treatment

Surgical Procedure for Konno-Rastan Aortic Root Enlargement 

1. Preoperative preparation

The patient is brought to the operating room, where general anesthesia is induced, and endotracheal intubation is performed. Preoperative vascular access is secured, including the following:

• Arterial line for continuous hemodynamic monitoring
• Peripheral and central venous lines for fluid and medication administration

The patient is positioned appropriately for surgery, and the surgical site is prepped and draped sterilely. The surgical checklist is confirmed.

2. Surgical exposure

• A midline median sternotomy is performed.
• The thymus is divided or subtotally resected in pediatric patients.
• The pericardium is opened and harvested if needed for patch reconstruction.
• The heart is suspended in a pericardial cradle for optimal exposure.

3. Initiation of cardiopulmonary bypass

• Systemic heparinization is administered, and adequacy is confirmed by activated clotting time (ACT).
• Aortic and bicaval cannulation is performed.
• A vent catheter is inserted into the left ventricle via the right superior pulmonary vein.
• A CO2 insufflation line is placed to minimize the risk of air embolism.
• The patient is cooled to the desired systemic temperature for myocardial protection.
• The aorta is cross-clamped, and antegrade cardioplegia is administered.
  • If associated aortic regurgitation is present, an aortotomy is performed, and ostial cardioplegia is given.

4. Aortotomy and initial inspection

• The aortotomy is performed obliquely, extending toward the left-right coronary commissure to facilitate later extension for the Konno incision.
• The aortic valve and left ventricular outflow tract are inspected.
• The pulmonary artery is snared to maintain a bloodless surgical field.

5. Right ventricular outflow tract incision

• The RVOT is opened with an incision just below the pulmonary valve.

6. Konno incision & LVOT enlargement

• The Konno incision is made in the aorta, starting just above the left-right commissure and extending through the commissure into the interventricular septum, stopping when the septal artery is visible.
• The incision depth is determined based on the required degree of root enlargement.
• If present, a subvalvular membrane is excised.
• If needed, an additional myectomy is performed.
• The adequacy of LVOT resection and a widely open outflow tract is confirmed.

7. Reconstruction of the Aortic Annulus and LVOT

• Pledgetted sutures are placed on the aortic annulus to implant the prosthetic aortic valve.
• The ventricular septal incision is closed using a bovine pericardial patch or glutaraldehyde-treated autologous pericardium, extending upwards through the aortic root using continuous polypropylene sutures.
• The junction between the septum and aortic root forms the neo-annulus, where pledgetted sutures are inserted, with the pledgets positioned toward the RVOT side.
• The ventricular septal patch is reinforced with additional interrupted sutures to prevent residual ventricular septal defects (VSD).

8. Prosthetic aortic valve implantation

• The prosthetic aortic valve is sized and implanted into the aortic root, secured with pledgetted sutures around the annulus.
• Free movement of all aortic prosthesis leaflets is verified.

9. Closure of aortotomy and RVOT reconstruction

• The superior part of the ventricular septal patch is used to close the aortotomy.
• The RVOT is reconstructed using a patch:
  • Continuous polypropylene sutures are used on the RVOT muscle side.
  • Continuous or interrupted sutures secure the superior margin.

10. Completion of the procedure

• The heart is deaired, and the aortic cross-clamp is removed.
• The patient is rewarmed and weaned off cardiopulmonary bypass (CPB).

Postoperative transesophageal echocardiography (TEE) is performed to confirm these:

• Proper function of the prosthetic valve
• Absence of paravalvular leak
• Adequate and wide-open LVOT without a significant gradient
• Absence of residual VSD
• Unobstructed RVOT
• Ventricular function assessment

Once hemodynamics are stable, the patient is decannulated, and protamine is administered to reverse heparinization.

• Chest tubes and temporary pacing wires are placed.
• Hemostasis is confirmed, and the sternum is closed.
• The patient is transferred to the intensive care unit for postoperative recovery and monitoring.[1]

Complications

Complications of the Konno-Rastan Procedure

Like any cardiac surgery, the Konno-Rastan procedure carries the risk of routine postoperative complications, including the following:

• Bleeding
• Infection
• Thromboembolic events
• Hemodynamic instability

However, specific complications associated with this procedure include these:

 Conduction System Injury

Complete atrioventricular block due to injury to the conduction system, often necessitating permanent pacemaker implantation.

Residual Ventricular Septal Defect 

• Incomplete closure of the ventricular septal incision can result in a residual VSD, requiring reoperation or catheter-based closure.

 Septal Artery Injury

• Damage to the septal artery during the Konno incision may lead to myocardial ischemia or ventricular dysfunction.

 Aortopulmonary Fistula

• There are reports of aortopulmonary fistula formation following Konno-Rastan aortoventriculoplasty, likely due to improper closure or excessive tissue tension.

 Coronary Artery Compression

• Oversizing of the aortic prosthetic valve can lead to coronary artery compression, compromising myocardial perfusion and resulting in ischemic complications.

 Right ventricular outflow tract obstruction

• Improperly sized patches or misalignment during reconstruction can create a gradient in the RVOT, potentially leading to right ventricular dysfunction.
• Proper surgical planning, meticulous intraoperative technique, and postoperative echocardiographic assessment are critical in minimizing these risks and ensuring optimal outcomes.

Clinical Significance

There are many techniques for aortic root enlargement with posterior incision on the aortic annulus. Konno-Rastan-aorticoventriculoplasty is the only anterior root enlargement technique that is effective for relief of subvalvar, valvar and supravalvar aortic stenosis with good long-term outcomes and minimal complication rate. The additional patch on the right ventricular outflow tract makes it useful in cases with combined right and left ventricular outflow tract obstruction patients. The incision has been modified to spare the aortic annulus (modified Konno) for relief of subaortic stenosis. This procedure has also been used along with the Ross procedure with small aortic roots to accommodate a good size autologous pulmonary root in native aortic root position using a Konno incision to enlarge the aortic root followed by pulmonary autograft implantation; it is also specifically useful in patients with prior mitral valve replacement requiring aortic root enlargement since posterior enlargement of the annulus is not possible in such cases.

The K-R procedure is an effective and attractive treatment for LVOT enlargement, surgically incising the aortic root, the interventricular septum, and the anterior wall of the LVOT.[2] Various case series have shown that the K-R procedure, together with aortic valve replacement, provides optimal postoperative results with minimal associated mortality rates (<1%), low mean gradient (<10 mm Hg), and remission of the New York Heart Association IV-III symptoms to I-II. Likewise, the safety of this technique has been highlighted with a survival greater than 85% and without deterioration of ventricular function in a 20-year follow-up (LVEF, 58%–62%).[3][4][5]

Enhancing Healthcare Team Outcomes

Konno-Rastan aortic root enlargement is an important adjunct technique to have reserved for special cases which require anterior root enlargement. An interdisciplinary review among the cardiac surgeon, anesthetist and cardiologist of the case planned for such a procedure is important. A diagnosis of associated subvalvar aortic stenosis requires to be reviewed to determine the extent of intervention required for LVOT. Debriefing the surgical steps with the cardiac operating room staff helps to get the materials prepared in time. Prosthetic valve and its step up or down sizes can be kept ready along with the sizers.

The glutaraldehyde required for treating the pericardial patch or the bovine pericardial patch can be kept available saving intraoperative wait time. Specific sutures required for each suture line if communicated preoperatively will make intraoperative steps smoother to perform. Hemostatic agents that will be required towards the later end of the surgery can be collected beforehand and made available. A preoperative discussion with the perfusionist regarding the expected cross clamp time, amount, and method of cardioplegia, degree of hypothermia and strategy for venting helps achieve good myocardial protection. A good post operative plan in terms of control of blood pressures and bleeding, management of disturbances in heart rhythm, pain relief, sedation and weaning from anesthesia. Ensuring proper interdisciplinary management will lower morbidity and give improved outcomes.

Nursing, Allied Health, and Interprofessional Team Interventions

The Konno-Rastan aortic root enlargement is a complex cardiac surgical procedure that requires a team formed by cardiac surgeons, cardiac anesthesiologists, trained cardiac nurses, cardiologists, perfusionists, intensivists, operating room technicians, pharmacists, physical therapists, nutritionist and many other specialist hospital staff to work in coordination to provide the best results for the patient. Each member of the team plays a significant role in the conduction of this procedure. Coordinated interprofessional team interaction helps to achieve a best outcome in terms of outstanding surgery, smooth recovery and better quality of life for the patient.

Nursing, Allied Health, and Interprofessional Team Monitoring

Every team member is responsible for delivering the best possible input from their side and be alert regarding possibility of development of issues that can delay, disturb or deteriorate the quality of care provided to the patient. Close monitoring of the events at each stage of the procedure helps avoid complications and ensure a good outcome.