Surgical management of complex and tunnel-like subaortic stenosis

Perioperative and Anesthetic Considerations in Pediatric Valvar and Subvalvar Aortic Stenosis

Aortic stenosis (AS) is a common form of left ventricular outflow tract obstruction (LVOTO) in children with congenital heart disease. This review specifically considers the perioperative features of valvar (VAS) and subvalvar AS (subAS) in the pediatric patient. Although VAS and subAS share some clinical features and diagnostic approaches, they are distinct clinical entities with separate therapeutic options, which range from transcatheter intervention to surgical repair. We detail the pathophysiology of AS and highlight the range of treatment strategies with a focus on anesthetic considerations for the care of these patients before, during, and after intervention.

Subvalvular Aortic Stenosis: Learning From Human and Canine Clinical Research

Subvalvular aortic stenosis (SAS) is the most common congenital heart disease (CHD) in dogs and is also prevalent in human children. A fibrous ridge below the aortic valve narrows the left ventricular outflow tract (LVOT) and increases blood flow velocity, leading to devastating side effects in diseased patients. Due to the similarities in presentation, anatomy, pathophysiology, cardiac development, genomics, and environment between humans and dogs, canine SAS patients represent a critical translational model of human SAS. Potential adverse outcomes of SAS include arrhythmias, left-sided congestive heart failure, endocarditis, exercise intolerance, syncope, and sudden cardiac death. The greatest divergence between canine and human SAS clinical research has been the standard of care regarding treatment of these outcomes, with pharmacological intervention dominating best practices in veterinary medicine and surgical intervention comprising the standard practice for human SAS patients. Regardless of the species, the field has yet to identify a treatment option to prevent disease progression or permanently remove the fibrous ridge, but historical leaps in SAS research support a continued translational approach as the most promising method for achieving this goal.

Surgical Considerations in Interrupted Aortic Arch

Interrupted aortic arch (IAA) is a rare congenital anomaly with several anatomical variants and is often associated with other intracardiac and/or extracardiac congenital anomalies. Historically, associated with high early mortality, outcomes for this anomaly have improved in recent eras with advances in perioperative and anesthesia management and refinements in surgical technique. This review provides a description of surgical anatomy, anatomical classifications, and associated congenital lesions as well as an examination of the perioperative and surgical management of IAA in the contemporary surgical era.

Modified Konno operation for diffuse subaortic stenosis

The modified Konno operation is designed to provide relief of diffuse subaortic stenosis, while preserving the native aortic valve. The aorta and the right ventricular infundibulum are opened. The upper part of the subaortic stenosis is incised through the aortic orifice. The conal septum is incised and the septotomy is extended across the stenotic area. The obstructive tissue is removed (mainly from the left-handed rim of the septotomy) and the conal septum is enlarged with a prosthetic patch. The aorta is closed and the right ventricular infundibulum is enlarged. Early and late mortality rates are low. Potential morbidity (complete heart block, residual ventricular septal defect, iatrogenic aortic insufficiency, right ventricular outflow tract obstruction) should be minimized by a careful surgical technique. The modified Konno operation is indicated in patients with diffuse subaortic stenosis and a normal aortic orifice; this includes patients with severe forms of hypertrophic obstructive cardiomyopathy and children with tunnel subaortic stenosis and a normal aortic orifice; the modified Konno procedure provides long-lasting relief of the obstruction. In patients with tunnel stenosis and a borderline-sized aortic annulus, residual obstruction may develop at the valvar level and need reoperation; the modified Konno operation can, however, delay aortic valve replacement.

Fixed subaortic stenosis: a clinical dilemma for clinicians and patients

Subaortic stenosis carries considerable morbidity and mortality. In most cases, patients have an underlying left ventricular outflow tract morphology that promotes turbulence at the outflow tract, which induces the development of subaortic fibromuscular tissue. A subset of patients will progress to develop severe stenosis and aortic regurgitation, but it has been difficult to determine which patients are at risk. While resection of the subaortic tissue improves immediate outcome, many patients have recurrence of both stenosis and regurgitation, questioning the efficacy of surgical intervention in asymptomatic patients. This review article describes the current understanding of the etiology, treatment, and prognosis of subaortic stenosis.

Transcatheter aortic valve implantation in surgically repaired double outlet right ventricle

A 52-year-old male patient, with a medical history of surgically repaired double outlet right ventricle presented with severe aortic stenosis (AS) and hepatitis C with cirrhosis, presented with New York Heart Association Class IV heart failure. During evaluation for a liver transplant, he was deemed a poor surgical candidate due to his aortic valve disease and cirrhosis with model for end-stage liver disease score of 14. Transthoracic echocardiogram showed severe AS with a mean gradient of 62 mm Hg and calculated aortic valve area of 0.74 cm(2) with a normal ejection fraction of 65%. The patient underwent transfemoral implantation of a 23-mm Edwards Sapien commercial heart valve with significant mean gradient reduction across the aortic valve from 62 to 13 mm Hg. The patient was observed in the coronary care unit and discharged home 2 days postprocedure with his clinical symptoms greatly improved.

Modified Konno procedure: surgical management of tunnel-like left ventricular outflow tract stenosis

Left ventricular outflow tract stenosis represents 1-2 % of all congenital anomalies. In particular, tunnel-like left ventricular stenosis which is one type of fixed left ventricular outflow stenosis requires aggressive surgery to reduce the left ventricular outflow gradient. The purpose of the modified Konno procedure is to release fixed left ventricular outflow tract stenosis while preserving the native aortic valve and its function. Although the clinical results of the modified Konno procedure are acceptable, it is necessary to precisely understand this procedure and the anatomy of the left ventricular outflow tract in order to avoid complications.

Canadian Cardiovascular Society 2009 Consensus Conference on the management of adults with congenital heart disease: outflow tract obstruction, coarctation of the aorta, tetralogy of Fallot, Ebstein anomaly and Marfan's syndrome

With advances in pediatric cardiology and cardiac surgery, the population of adults with congenital heart disease (CHD) has increased. In the current era, there are more adults with CHD than children. This population has many unique issues and needs. Since the 2001 Canadian Cardiovascular Society Consensus Conference report on the management of adults with CHD, there have been significant advances in the field of adult CHD. Therefore, new clinical guidelines have been written by Canadian adult CHD physicians in collaboration with an international panel of experts in the field. Part II of the guidelines includes recommendations for the care of patients with left ventricular outflow tract obstruction and bicuspid aortic valve disease, coarctation of the aorta, right ventricular outflow tract obstruction, tetralogy of Fallot, Ebstein anomaly and Marfan's syndrome. Topics addressed include genetics, clinical outcomes, recommended diagnostic workup, surgical and interventional options, treatment of arrhythmias, assessment of pregnancy risk and follow-up requirements. The complete document consists of four manuscripts that are published online in the present issue of The Canadian Journal of Cardiology. The complete document and references can also be found at www.ccs.ca or www.cachnet.org.

Long-term Outcome and Risk of Heart Block After Surgical Treatment of Subaortic Stenosis

Although mortality following repair of subaortic obstruction is low, aggressive resection may increase morbidity. We sought to evaluate outcomes and risk of atrioventricular heart block (AVB) after subaortic resection in the current era. Simple obstruction was defined as a discrete subaortic membrane and complex as multilevel or diffuse narrowing. Limited resection included membranectomy and limited myomectomy. Aggressive resection included Konno, modified Konno, and Ross. Specified variables were obtained from a chart review. The 185 consecutive patients (1991-2008) ranged in age from 1 day to 21.8 years (5.1 ± 5.1 years) with 2 early and 4 late deaths. Actuarial survival was 97%, 95%, and 95% at 1, 5, and 10 years, respectively. Reoperations were required in 29 of 185 patients (15.7%); 2 required a third operation (1%). Freedom from reoperation in all patients was 97%, 83%, and 73% at 1, 5, and 10 years, respectively. Accessory mitral valve tissue ( P < .001) and age <3 months ( P = .004) predicted the need for reoperation. Transient or permanent high-degree AVB was documented in 33 of 185 patients (17.8%). Complex anatomy ( P = .01) and aggressive resection ( P < .001) increased the risk of acquiring AVB. The AVB was permanent in 21 of 185 (11.4%) patients, and pacemaker implantation was undertaken in 20 of 185 (10.8%) patients. Complex anatomy ( P = .04) and modified Konno procedure ( P = .03) increased the risk of acquiring a pacemaker. Aggressive resection lowered the frequency of recurrence but increased the risk of AVB. When aggressive resection is considered for long-term relief of subaortic obstruction, the risk of reobstruction must be balanced with the risk of AVB and the need for pacemaker implantation.

Surgical management of left ventricular outflow tract obstruction after biventricular repair of double outlet right ventricle

Regardless of the preoperative morphology and the type of operation, left ventricular outflow tract obstruction (LVOTO) after biventricular repair of double outlet right ventricle (DORV) may develop. This report presents our 10-yr experience with surgical management of LVOTO after biventricular repair of DORV. Between 1996 and 2006, 15 patients underwent reoperation for subaortic stenosis after biventricular repair of DORV. The mean age at biventricular repair was 23.3+/-18.3 months (1.1-64.2). Biventricular repairs included tunnel constructions from the left ventricle to the aorta in 14 cases and an arterial switch operation in one. The mean left ventricle-to-aorta peak pressure gradient was 54.0+/-37.7 mmHg (15-140) after a mean follow-up of 9.5+/-6.3 yr. We performed extended septoplasty in nine patients and fibromuscular resection in six. There were no early or late mortality. There was one heart block and one aortic valve injury after an extended septoplasty, and two and one after a fibromuscular resection. No patient required reoperation for recurrent subaortic stenosis. The mean pressure gradient was 11.2+/-11.4 mmHg (0-34) after a mean follow-up of 5.6+/-2.7 yr. Extended septoplasty is a safe and effective method for the treatment of subaortic stenosis, especially in cases with a long-tunnel shaped LVOTO.

Implications of incising the ventricular septum in double outlet right ventricle and in the Ross-Konno operation

OBJECTIVE

Incision into the ventricular septum in complex biventricular repair is controversial, and has been blamed for impairing left ventricular function. This retrospective study evaluates the risk of a ventricular septal incision in patients undergoing double outlet right ventricle (DORV) repair and Ross-Konno procedure.

METHODS

From January 2003 to September 2007, 11 patients with DORV had a ventricular septum (VS) incision and 12 DORV patients did not. Sixteen patients had a Ross-Konno, and 16 had an isolated Ross procedure. The ventricular septal incision was made to match at least the diameter of a normal aortic annulus. In DORV, the VSD was enlarged superiorly and to the left. In the Ross-Konno, the aortic annulus was enlarged towards the septum posteriorly and to the left.

RESULTS

The median follow-up for the study is 19 months (1 month-4 years). For DORV, there were no significant differences in discharge mortality (p=0.22), late mortality (p=0.48), or late mortality plus heart transplant (p=0.093). Although patients with DORV and VSD enlargement have a more complex postoperative course, there were no differences in ECMO use (p=0.093), occurrence of permanent AV block (p=0.55), left ventricular ejection fraction (LVEF) (p=0.40), or shortening fraction (LVSF) (p=0.50). Similarly, for the Ross-Konno there were no significant differences in discharge mortality (p=0.30), late mortality (p=NS), LVEF (p=0.90) and LVSF (p=0.52) compared to the Ross, even though the Ross-Konno patients were significantly younger (p<0.0001).

CONCLUSION

Making a ventricular septal incision in DORV repair and in the Ross-Konno operation does not increase mortality and does not impair the LV function. The restriction of the VSD remains an important issue in the management of complex DORV. These encouraging results need to be confirmed by larger series.

Correction of discrete subaortic stenosis with abnormal chordae tendineae

The case of a 52-year-old woman with subvalvular aortic stenosis and aortic regurgitation is presented. Mitral regurgitation was associated, due to insertion of two abnormal chordae tendineae at the apex of the anterior papillary muscle and at the free border of the subvalvular membranous annulus. This abnormality displaced the anterior papillary muscle, thus applying a traction at the mitral leaflet. The patient was operated on through a valve-sparing approach, in which the discrete subaortic stenosis was removed through aortotomy and the ectopic chordae were excised. Suture mitral annuloplasty completed the procedure. Aortic and mitral insufficiency almost disappeared at follow-up. From the examination of this case and from a review of pertinent literature it emerges that in event of similar complex congenital abnormalities without intrinsic valve disease, a conservative approach should be chosen so that valve replacement can be avoided.

Surgical treatment of subaortic obstruction in adolescent and adults: long-term follow-up

Subaortic stenosis (SAS) is a wide spectrum of anatomical derangements ranging from a discrete fibrous membrane to tortuous fibrous tunnel with or without aortic annulus hypoplasia. We have reviewed 88 patients undergoing surgery for SAS over a 15-year period. There were 47 male and 41 female patients with a mean age of 19.8 +/- 10.6 years (range 11 to 39). Fifty-eight patients had discrete subaortic membrane, and 30 patients had diffuse tunnel subvalvular stenosis. The mean systolic pressure gradients were found to be 86.5 +/- 31.4 mmHg (range 48 to 145 mmHg). Ten patients had mild and 13 patients had moderate-to-severe aortic insufficiency (AI) preoperatively. Nine patients had bicuspid aortic valve. Forty patients (45.4%) had associated cardiac lesions. Isolated membranectomy was performed in six patients. Membranectomy associated with septal myectomy was done in 52 patients. Fifteen patients of them associated hypoplasia of the aortic orifice necessitated aortic valve replacement (AVR) using the Konno-Rastan procedure. Fifteen patients with tunnel SAS and normal aortic valves underwent a combined approach for valve sparing, a modified Konno procedure with patch septoplasty. Also eight patients required AVR because of the severity of AI and five patients aortic reconstruction procedures. Aortic commissurotomy was performed to relief of stenosis in four patients. There were three early deaths (3.4%) and one late death (1.1%) all after the Konno-Rastan procedure. Eight patients (9.1%) had permanent conduction abnormalities. Postoperative left ventricle-aorta gradient was significantly decreased at early postoperative period (p < 0.001) and ranged from 10 to 25 mmHg (mean 14.1 +/- 4.3). Fourteen patients (16.5%) were reoperated for recurrent obstruction or progression of AI. The mean reoperation interval was 4.4 +/- 1.7 years (range 2 to 8 years). Five-year reoperation-free survival was 88.0 +/- 3.6% and 12.5-year reoperation-free survival was 75.5 +/- 7.0%. Our results of aggressive surgical approach of subvalvular aortic stenosis produces relief of obstruction and frees the valve leaflets, significantly reducing associated AI with long-term survival and long-term adequate relief of left ventricular outflow tract obstruction.

Surgical management of tunnel-like subaortic stenosis via ventricular septal defect in a patient with the interrupted aortic arch

A 24-day-old male with interrupted aortic arch (type B), ventricular septal defect, and tunnel-like subaortic stenosis underwent a one-stage surgical treatment. The operative procedure comprised reconstruction of the aortic arch, transatrial excision of the subaortic fibromuscular tissue via the ventricular sepatal defect, and patch closure of the defect. The patient tolerated the procedure well and the postoperative echocardiography demonstrated a residual pressure gradient across the left ventricular outflow tract of 20 mmHg. Our result suggests that the transatrial surgical management of subaortic stenosis via the ventricular sepatal defect produces a safe and promising surgical option.

Surgical correction of subaortic stenosis via right ventriculotomy and septal resection in a dog

After 2 years of medical management with a beta-adrenoreceptor blocking agent, a 30-month-old castrated male Golden Retriever with subaortic stenosis was treated surgically because of progression of its condition. In an attempt to achieve complete relief of the left ventricular outflow obstruction, a modified Konno procedure consisting of right ventriculotomy and septal myectomy from the infundibular portion of the right ventricle was performed; this combination of procedures allowed wide resection of the septal portion of the left ventricular outflow obstruction. Two years after surgery, the mass of the dog's left ventricle had decreased and the peak calculated pressure gradient across the aortic valve had decreased to 40 mm Hg, compared with a preoperative value of 240 mm Hg; at that evaluation, the dog had gained weight and was able to play normally. It is suggested that use of this modified approach to the outflow tract may have a positive effect on long-term survival time in dogs with subaortic stenosis.

Left ventricular outflow tract obstruction

Left ventricular outflow tract obstruction can occur at the supravalvar, valvar, or subvalvar level. Each level of obstruction is associated with distinct symptomatology, natural history, and operative approach. Reconstructive techniques can usually be used with low operative risk and excellent immediate and longer-term outcomes. Valve replacement for valvar obstruction is advised when reconstruction is not possible. The Ross procedure has greatly improved the results of valve replacement in children.

Biventricular repair after Norwood palliation

BACKGROUND

In general, neonates with severe left ventricular outflow tract obstruction, aortic valvar stenosis or atresia, and arch hypoplasia with either interruption or coarctation, and a small left ventricle undergo Norwood palliation followed classically by a bidirectional cavopulmonary shunt and eventual modified Fontan. However, a subset of patients, usually neonates with a ventricular septal defect, may have adequate left ventricle and mitral valve sizes making them candidates for future biventricular repair (BVR). In view of the long-term advantage of BVR, the feasibility and outcome of this approach was studied. Additionally, echocardiographic data were reviewed in an attempt to develop objective prognostic criteria for selection of patients suitable for BVR.

METHODS

During a 4-year period, 8 of 58 infants undergoing Norwood palliation were identified as potential two-ventricle candidates. Their mean age was 6 days. Diagnoses included aortic atresia (n = 1), or aortic valve stenosis and subaortic stenosis (n = 7), with an interrupted aortic arch in 3 and coarctation in 4. All patients had a ventricular septal defect and a left ventricle that was considered to be apex forming. Mean mitral valve size was 11 mm (z-score = -1.7). Mean aortic valve size was 4.1 mm (mean z-score = -8.4).

RESULTS

All 8 patients survived Norwood palliation. Six subsequently underwent BVR with ventricular septal defect closure and a right ventricle to pulmonary artery conduit at a mean age of 7 months. One patient is awaiting repair, and 1 underwent a cavopulmonary shunt. At the time of BVR, mean mitral valve z-score was essentially unchanged at -1.4 (14 mm). No early deaths or late deaths occurred during a mean follow-up of 32 months.

CONCLUSIONS

A small subset of patients requiring Norwood palliation as newborns may be candidates for eventual BVR with low risk. In general, patients suitable for BVR have a mitral valve z-score of more than -3 and a normal-sized left ventricle. Recognition of neonatal BVR candidates enables consideration of complete neonatal repair. However, single-stage repair needs to be compared with the excellent results obtainable with the staged approach.

The anatomy of the septal perforating arteries in normal and congenitally malformed hearts

BACKGROUND

Many cardiac operations involve incisions and sutures on or near the ventricular septum. These jeopardize the septal perforating arteries. Our aim was to provide guidelines for the surgeon to predict the site of these vessels.

METHODS AND RESULTS

We dissected 50 hearts. In 16 of these we also conducted histologic examination of the area of the septum containing the atrioventricular node, the penetrating bundle (of His), and the branching atrioventricular bundle to elucidate the source of the vascular supply to these structures. The major perforating septal arteries arise from the superior interventricular artery or, in hearts with a rudimentary right ventricle, from the superior delimiting artery. The first is usually the largest. The location of this artery can be predicted relative to the position of the medial papillary muscle. In abnormal hearts, holes within the ventricular septum in the presence of a well-developed muscular outlet septum were found to deviate the path of the septal perforating arteries in a predictable manner. The triangular area bordered by the margin of the ventricular septal defect, the muscular outlet septum, and the medial papillary muscle is free of major perforating arteries. The histologic studies showed that the conduction tissues at the base of the ventricles tend to receive their blood supply from arteries arising from the inferior interventricular artery, except in double-inlet left ventricle, in which the arterial supply is from the right-sided delimiting artery.

CONCLUSION

The location of the first superior septal perforating artery is predictable in many cases. Its course leaves a triangular area on the muscular ventricular septum that is free of major arteries.