Pulmonary valve-moderator band distance and association with development of double-chambered right ventricle

Endothelial-to-Mesenchymal Transition as Underlying Mechanism for the Formation of Double-Chambered Right Ventricle

Double-chambered right ventricle (DCRV) is a progressive division of the right ventricular outflow tract (RVOT) often associated with a subaortic ventricular defect (VSD). The septation is caused by a mixture of hypertrophied muscle bundles and fibrous tissue, whereof the latter is of unclear pathogenesis. Our group has previously reported that flow disturbances lead to formation of fibroelastic tissue through a process called endothelial-to-mesenchymal transition (EndMT) but it is unclear whether the same mechanism exists in the RV. Tissue from patients undergoing repair of DCRV was examined to identify the histomorphological substrate of this tissue. Demographic and pre-/post-operative echocardiographic data were collected from nine patients undergoing surgery for DCRV. RVOTO tissue samples were histologically analyzed for myocardial hypertrophy, fibrosis, elastin content, and active EndMT (immunohistochemical double-staining for endothelial and mesenchymal markers and transcription factors Slug/Snail) and compared to four healthy controls. Indication for surgery were symptoms and progressive RVOT gradients. A highly turbulent flow jet through the RVOTO and VSD was observed in all patients with a preoperative median RVOT peak gradient of 77 mmHg (IQR 55.0-91.5), improved to 6 mmHg (IQR 4.5-17) postoperatively. Histological analysis revealed muscle and thick infiltratively growing fibroelastic tissue. EndMT was confirmed as underlying patho-mechanism of this fibroelastic tissue but the degree of myocardial hypertrophy was not different compared to controls (P = 0.08). This study shows for the first time that an invasive fibroelastic remodeling processes of the endocardium into the underlying myocardium through activation of EndMT contributes to the septation of the RVOT.

Congenital, acquired, or both? The only two congenitally based, acquired heart diseases

Discrete subaortic stenosis (DSS) is a type of left ventricular outflow tract obstruction whereas double-chambered right ventricle is a form of right ventricular outflow tract obstruction. Both of these cardiac malformations share lots of similar characteristics which classify them as acquired developmental heart diseases despite their congenital anatomical substrate. Both of them are frequently associated to ventricular septal defects. The initial stimulus in their pathogenetic process is anatomical abnormalities or variations. Subsequently, a hemodynamic process is triggered finally leading to an abnormal subaortic fibroproliferative process with regard to DSS or to hypertrophy of ectopic muscles as far as double-chambered right ventricle is concerned. In many cases, these pathologies are developed secondarily to surgical management of other congenital or acquired heart defects. Moreover, high recurrence rates after initial successful surgical therapy, particularly regarding DSS, have been described. Finally, an interesting coexistence of DSS and double-chambered aortic ventricle has also been reported in some cases.

Morphological classification of the moderator band and its relationship with the anterior papillary muscle

This study investigated and classified the various types of moderator band (MB) in relation to the anterior papillary muscle, with the aim of providing anatomical reference information and fundamental knowledge for use when repairing the congenital defects and understanding the conduction system. The study investigated 38 formalin-fixed human hearts of both sexes obtained from donors aged 38–90 years. The MB was evident in 36 of the 38 specimens (94.7%). The morphology of the MB and its connection with the APM took various forms. The MBs that had a distinct shape were classified into three types according to their shape: cylindrical column, long and thin column, and wide and flat column. Types 2 and 3 were the most common, appearing in 15 (41.7%) and 14 (38.9%) of the 36 specimens, respectively, while type 1 was observed in seven specimens (19.4%). Type 3 was divided into subtypes based on their length. The MB usually originated from a single root (91.7%), with the remainder exhibiting double roots. The pairs of roots in the latter cases had different shapes. The originating point of the MB ranged from the supraventricular crest to the apex of the ventricle. The most-common originating point was in the middle (25 of 36 specimens, 69.4%), followed by the upper third (13.9%), the lower third (11.1%), and the top fifth (5.6%) of the interventricular septum. This study has produced fundamental anatomical and clinical information that will be useful when designing cardiac surgical procedures.

Role of Echocardiograghy in Treating a Case of Double Chamber Right Ventricle with Delayed Presentation

The clinical diagnosis of double chamber right ventricle (DCRV) is not straightforward. Clinical history, clinical examination, 12-lead electrocardiogram, chest X-ray, and Echocardiography (echo) contribute to morphological diagnosis. Cardiac catheterization is essential for hemodynamic evaluation. A thorough presurgical workup helps the cardiac surgeon to choose the appropriate surgical approach and timing of surgery in an individual case. We present a case of a DCRV who presented to us in the fifth decade of life. Echo confirmed the morphological diagnosis and cardiac catheterization complemented the exact pull back gradient across the obstruction in the right ventricle. This patient was suggested muscle bundle resection and ventricular septal defect closure using right atrial approach.

An (In)Significant Ventricular Septal Defect and/or Double-Chambered Right Ventricle: Are There Any Differences in Diagnosis and Prognosis in Adult Patients

A double-chambered right ventricle (DCRV) is an uncommon congenital anomaly: the right ventricle (RV) is divided into two chambers due to the presence of an abnormally located muscular band or anomalous muscle hypertrophy in the subinfundibular part of RV outflow tract, with a variable degree of obstruction. Generally, DCRV is well recognized in childhood and misdiagnosed in adult patients. Transthoracic and/or transesophageal echocardiography are the mx0435;thods of choice for the diagnosis of DCRV. Due to limitations of echocardiography in adult patients, this entity may be missed, particularly if it presents concomitant with other congenital defects, and therefore additional imaging methods such as MRI or cardiac catheterization are required for a definitive diagnosis.

Surgical Outcomes and Postoperative Prognosis Beyond 10 Years for Double-Chambered Right Ventricle

Double-chambered right ventricle (DCRV) is a rare condition. Stenosis of DCRV is progressive, and early surgical intervention is recommended for patients whose symptoms and/or pressure overload of right ventricular (RV) inflow are progressive. However, there are few data regarding the postoperative course of DCRV, and the surgical indications for asymptomatic patients remain to be determined. We retrospectively investigated 38 consecutive patients who were diagnosed with DCRV and underwent surgical intervention from 1981 to 2009. Moreover, we identified 29 patients in whom long-term follow-up transthoracic echocardiographic data were available and investigated the postoperative recurrence of DCRV by evaluating the systolic pressure of RV inflow before, immediately, and in the long term after surgical intervention. The mean follow-up period was 11.0 ± 8.8 years. There were no deaths and no surgical reinterventions during the long-term follow-up period. Among 29 patients with long-term follow-up echocardiographic data, there was no recurrence of DCRV. In these patients, the systolic pressure of RV inflow by echocardiography before, immediately, and long-term after surgical intervention was 80 ± 26, 30 ± 11, and 25 ± 6 mm Hg, respectively. In conclusion, the surgical outcomes and postoperative prognosis beyond 10 years of DCRV are favorable, and neither recurrence of DCRV nor fatal arrhythmias develop during the long-term follow-up period.

Bands, Chords, Tendons, and Membranes in the Heart: An Imaging Overview

Crests, bands, chords, and membranes can be seen within the different cardiac chambers, with variable clinical significance. They can be incidental or can have clinical implications by causing hemodynamic disturbance. It is crucial to know the morphology and orientation of normal structures, aberrant or accessory muscles, and abnormal membranes to diagnose the hemodynamic disturbance associated with them. Newer generation computed tomographic scanners and faster magnetic resonance imaging sequences offer high spatial and temporal resolution allowing for acquisition of high resolution images of the cardiac chambers improving identification of small internal structures, such as papillary muscles, muscular bands, chords, and membranes. They also help in identification of other associated complications, malformations, and provide a road map for treatment. In this article, we review cross-sectional cardiac imaging findings of normal anatomical variants and distinctive imaging features of pathologic bands, chords, or membranes, which may produce significant hemodynamic changes and clinical symptomatology.

Double chambered right ventricle with ventricular septal defect in adults: case series and review of the literature

Double-chambered right ventricle (DCRV) is an uncommon congenital anomaly in which anomalous muscle bands divide the right ventricle into two chambers; a proximal high-pressure and distal low-pressure chamber. It may be associated with mid right ventricular obstruction. It is commonly associated with other congenital anomalies, most frequently perimembranous ventricular septal defect (PM-VSD). We herein present 5 adult patients with concomitant DCRV and PM-VSD who varied in their symptomatic presentations and the ways of management.

Imaging pitfalls, normal anatomy, and anatomical variants that can simulate disease on cardiac imaging as demonstrated on multidetector computed tomography

Advances in computed tomography have led to continuous improvement in cardiac imaging. Dedicated postprocessing capabilities, faster scan times, and cardiac gating methods reveal details of normal cardiac anatomy and anatomic variants that can mimic pathologic conditions. This article will review normal cardiac anatomy and variants that can mimic disease. Radiologists should be familiar with normal cardiac anatomy and anatomic variants to avoid misinterpretation of normal findings for pathologic processes.

Right ventricular apical sequestration: demonstration of a rare variant of double-chambered right ventricle with MRI

A 15-year-old boy sustained cardiac arrest and was ultimately found to have imaging characteristics consistent with a right ventricular apical sequestration, a sub-variety of double-chambered right ventricle. This is a unique report demonstrating the MRI findings of this rare variation.

[Presentation form and evolution of double-chambered right ventricle]

INTRODUCTION

The double-chambered right ventricle (DCRV) is an uncommon congenital heart disease; it represents the 0,5% of these congenital cardiopathies.

OBJECTIVE

To describe the clinical and echocardiographic characteristics of a series of 11 patients.

METHODS

Eleven patients with DCRV were studied. A complete medical history, chest radiograph, electrocardiogram, and transthoracic echocardiography were performed.

RESULTS

The median age of studied patients was 10 years. The 36.45% of cases were asymptomatic and the diagnosis was made by echocardiography. Other cases had weakness during food in the lactancy stage and worsening of NYHA functional class in older children. The echocardiogram showed double-chambered right by a muscular band in all studied patients. The most frequent associated anomalies were: ventricular septal defect, patent foramen ovale, subvalvular aortic stenosis, and Fallot's Tetralogy. Seven patients went to surgical treatment and now 6 of them are in NYHA functional class i.

CONCLUSIONS

This paper has a special importance, because is the biggest series of patients with double-chambered right ventricle in Mexico and the results are comparable to the studies reported in the literature. The worsening of the NYHA functional class was the predominate symptom. The clinical manifestations can be presented from the lactancy to adulthood and the degree of obstruction could have a progressive character. The echocardiography is the method of choice in the diagnosis of these patients. The 91% of patients with DCRV who went to surgical treatment had excellent hemodynamic and functional results in the mid-follow-up.

Outcomes of surgical repair of double-chambered right ventricle

BACKGROUND

We reviewed our experience with surgical repair of double-chambered right ventricle and long-term outcome.

METHODS

From November 1970 to February 2008, repair of double-chambered right ventricle was performed in 61 patients (31 males). The median age was 13 years (interquartile range, 2 months to 64 years); 10 patients were infants (16%). Mean preoperative right ventricular outflow tract pressure gradient was 67±37 mm Hg. An associated ventricular septal defect was present in 50 patients (82%).

RESULTS

There were 2 (3%) early deaths due to persistence of low cardiac output postoperatively, despite complete relief of the right ventricular gradient. The overall mean postoperative gradient was 2±4.5 mm Hg. Late follow-up was complete in 92% (mean, 7.4±7.9 years; maximum, 37 years). Late survival was 90% at 10 years. There were 3 late deaths due to heart failure in 2 patients and sudden death in 1 patient, all occurring before 1997. No patients required reoperation for residual or recurrent right ventricular obstruction.

CONCLUSIONS

Surgical correction of double-chambered right ventricle results in excellent functional and hemodynamic long-term results, with complete relief of the right ventricular obstruction. The presence of a double-chambered right ventricle should be considered in anomalies with high or persistent right ventricular outflow tract obstruction.

Surgical repair of double-chambered right ventricle in adulthood

The aim of this study was to investigate a rare subset of adult patients with double-chambered right ventricle, pertaining to clinical presentation, rhythm disturbances, surgical approach, and results of surgical repair. A retrospective review of our records revealed that 14 adults had undergone surgical repair of double-chambered right ventricle from 1990 to 2010. Their median age was 25.5 years, and their median weight was 50 kg. Patients presented with various symptoms, the most common being dyspnea on exertion. The mean systolic pressure gradient across the obstruction was 69.8 ± 23.1 mm Hg. The most common associated anomaly was ventricular septal defect. Significant rhythm disturbances were present in 4 patients. Transatrial repair was undertaken in 5 patients, a combined transatrial and transpulmonary approach was used in 4, and a right ventriculotomy in 5. There was no mortality at a median follow-up of 5.1 years. A mild right ventricular outflow tract gradient was noted in 2 patients. Medical management was required for rhythm disturbances in 2 patients. Double-chambered right ventricle can present in adulthood, often with vague symptoms. The midterm results of surgical correction are satisfactory. Long-term follow-up is necessary to detect late arrhythmias.

Characteristics of double-chambered right ventricle in adult patients

BACKGROUND/AIMS

This study evaluated the clinical features of double-chambered right ventricle (DCRV) in adults. Most cases of DCRV are diagnosed and treated during childhood. Consequently, very few reports include cases in which its clinical characteristics are evident in adults.

METHODS

We reviewed the clinical data for 10 adult patients (age > or = 18 years) with DCRV.

RESULTS

Electrocardiogram showed right ventricular hypertrophy in 3 DCRV patients. All cases were associated with ventricular septal defect (VSD; 7 for perimembranous, 2 for muscular outlet, and 1 for the subarterial type). Surgical correction was done for 7 DCRV patients all of whom survived operations. Their follow-up echocardiogram showed the pressure gradient in their right ventricle was significantly decreased from 69.4 +/- 17.2 mmHg preoperatively to 10.2 +/- 5.0 mmHg postoperatively (p < 0.05). In the short-term follow-up, there was no significant increase in the pressure gradient in the right ventricle.

CONCLUSIONS

There are lots of cases of DCRV that are not diagnosed accurately in adults. In our experience, all DCRV cases had VSD and surgical correction of these cases showed excellent results. Therefore, accurate diagnosis of DCRV is necessary so that DCRV is not overlooked and operations are enabled within an appropriate time.

Double-chambered right ventricle in an adult patient diagnosed by transthoracic echocardiography

Background

Double-chambered right ventricle is a rare congenital disease frequently misdiagnosed in the adult patient. An anomalous muscle band divides the right ventricle in two cavities causing variable degree of obstruction. Although echocardiography is considered a useful method for the diagnosis of this pathology in children, it has been recognized the transthoracic scanning limitation in adults.

Case presentation

A 29 year-old patient with double-chambered right ventricle presenting mild exercise intolerance referred for follow up of a known ventricular septal defect in whom a complete diagnosis was obtained based only on transthoracic two dimensional echocardiography without the needing of cardiac catheterization.

Conclusion

Based on non invasive echocardiographic diagnosis, patient was referred to surgical correction, which was completely successful.

Deficiency of Actinin-Associated LIM Protein Alters Regional Right Ventricular Function and Hypertrophic Remodeling

Targeted deletion of actinin-associated LIM protein (ALP) in mice leads to right ventricular (RV) dysplasia and a mild RV cardiomyopathy. Although the phenotype has been thoroughly characterized, the mechanisms leading from the cytoskeletal defect to the disease are unclear. We hypothesized that ALP deficiency may be associated with (1) changes in regional systolic dysfunction and (2) regional dysregulation of hypertrophic growth, in accordance with the restricted expression of ALP in the outflow tract of the RV. We examined RV regional epicardial systolic strains with respect to end-diastole in ALP knockout (ALPKO) mice and wild-type controls using an open-chest preparation. Strain components were consistently lower in the ALPKO mice than wild-type controls (second principal strain E2: p = 0.05). RV pressure was slightly but not significantly lower in ALPKO mice as well. To assess regional growth, geometric remodeling was analyzed in ALPKO and wild-type mice after 4 weeks of chronic hypoxia (11% oxygen). The average amount of RV wall thickening in response to hypoxia was reduced to 11% in the ALPKO mice compared with 44% in the wild-type controls. In summary, the results are consistent with the view that disruption of ALP is associated with diminished RV contractile function as well as altered hypertrophic remodeling.

Rapid progression of midventricular obstruction in adults with double-chambered right ventricle

OBJECTIVE

The purpose of this study was to determine the rate of progression of midventricular obstruction in adolescents and adults with double-chambered right ventricle.

METHODS

Clinical and echocardiographic findings in 45 patients (mean age 26 +/- 6 years, range 15-44) diagnosed with double-chambered right ventricle were retrospectively analyzed. Twenty patients underwent surgical repair before the age of 15 years. The relationship between Doppler midventricular pressure gradient and patient age was analyzed in 25 patients without previous repair. Sequential change in midventricular obstruction was determined for patients with 2 or more Doppler echocardiographic examinations performed within at least a 2-year interval.

RESULTS

Right midventricular pressure gradient in nonrepaired patients was 70 +/- 38 mm Hg (range 25-150). A significant relationship between midventricular obstruction and patient age (r = 0.64, P <.001) was found. Midventricular pressure gradient at initial evaluation was 32 +/- 27 mm Hg in 16 patients < 25 years and 73 +/- 45 mm Hg in 9 patients >/= 25 years (P <.03). After the initial study, 5 patients underwent surgical repair and 13 patients without repair were followed up for a period of 6.1 +/- 2.7 years (range 2-9), in which midventricular pressure gradient increased from 32 +/- 26 mm Hg to 67 +/- 35 mm Hg (P <.001). The slope of the change in midventricular pressure gradient was 6.2 +/- 3 mm Hg per year of follow-up. Seven more patients underwent surgical repair during follow-up due to progression of the obstruction. There was no mortality nor residual midventricular obstruction in surgically repaired patients.

CONCLUSIONS

Mild right midventricular obstruction shows a fast rate of progression in adolescents and young adults. Thus, close clinical and echocardiographic follow-up is advised, and surgical repair should be considered if significant progression of obstruction is detected.

Types of obstructions in double-chambered right ventricle: mid-term results

BACKGROUND

The double-chambered right ventricle (DCRV) is increasingly recognized as a distinct obstruction entity. The nature of the obstruction is not well defined.

METHODS

Patients with DCRV were prospectively studied during the last 4 years according to the following criteria: 1) pressure gradient by echo Doppler and cardiac catheterization within the right ventricle; 2) angiographic demonstration, and 3) surgical confirmation.

RESULTS

From March 1997 to March 2001, 10 new cases were included. Age ranged from 2 to 14 years (mean 9.5 +/- 4.4 years), weight ranged from 9.9 to 75 kg (mean 23 +/- 13.6 kg), and height from 0.85 to 1.48 m (mean 114 +/- 19 cm). Systolic gradient by echo Doppler ranged from 20 to 135 mmHg (mean 86 +/- 44 mmHg) and by cardiac catheterization, 18 to 130 mmHg (mean 78 +/- 35 mmHg). In terms of angiographic findings, in six patients the right ventriculogram showed an oblique and low obstruction; in four patients the obstruction was high and horizontal. With regard to surgical findings, angiographic findings were confirmed by the surgeon except in one patient, in whom both types of obstruction were present. No mortality was observed. With follow-up 4 to 40 months after surgery (mean 24 +/- 15 months), 8 of 10 patients were evaluated; all corresponded to class I NYHA. Systolic gradient by echo Doppler ranged from 0 to 11 mmHg (mean 4 +/- 6 mmHg).

CONCLUSIONS

DCRV IS PRODUCED BY THE FOLLOWING THREE TYPES OF MUSCULAR OBSTRUCTIONS: low and oblique obstruction; high and horizontal obstruction, and mixed obstruction. Mid-term surgical results are satisfactory.

Double-chambered right ventricle presenting in adulthood

BACKGROUND

Double-chambered right ventricle is a form of right ventricular outflow tract obstruction that develops over time, often in patients with an abnormally short distance between the moderator band and pulmonary valve. This lesion typically presents in childhood or adolescence and is often accompanied by a ventricular septal defect. Only a handful of previous cases have been described in which double-chambered right ventricle occurred in adulthood.

METHODS

Since 1992, three patients more than 30 years old (38, 43, and 66 years of age) have presented at our institution with unusual symptoms or a previous incorrect diagnosis. We reviewed the clinical data in these patients.

RESULTS

Presenting symptoms included syncope, angina, and severe dyspnea resembling pulmonary hypertension. In 1 patient, disease was categorized as New York Heart Association class IV, and in the other 2 as class III. Coexisting anomalies included a patent foramen ovale or secundum atrial septal defect in 2 patients, a small ventricular septal defect in 1 (with a probable history of ventricular septal defect in another), and mild aortic regurgitation in 1. All patients required urgent or emergent operations, with peak pressures in the proximal right ventricular chamber of 135 to 180 mm Hg and severely depressed left ventricular function in 1 patient. Resection of the anomalous right ventricular muscle bundles was achieved through a right atrial approach in all patients. All patients were alive with improved functional status at follow-up, which was between 15 and 40 months.

CONCLUSIONS

Right ventricular outflow tract obstruction resulting from a double-chambered right ventricle is rare in adults, but when it does occur it can present with unusual symptoms. When evaluating the patient with signs or symptoms of primary right heart failure, cardiologists should make an effort to image the entire right heart complex. Subcostal echocardiography can facilitate adequate visualization of the right ventricle when it is difficult to distinguish the subpulmonary outflow tract from the parasternal and apical windows.

The nature of the obstructive muscular bundles in double-chambered right ventricle

OBJECTIVE

Our goal was to establish the morphologic nature of the obstructive muscular lesions in double-chambered right ventricle.

METHODS

We based our morphologic observations on 10 normal hearts and on the surgical findings in 26 patients, aged 0.5 to 24 years, with a mean of 6.9 years (SD 5.8 years). In the normal hearts, we measured the distance from the pulmonary valve to the apex of the right ventricle and from the takeoff of the moderator band to the ventricular apex. From angiograms available in 20 patients, using the frontal view, we then measured the distance from the pulmonary valve to the apex of the right ventricle and from the midpoint of the obstructive lesion to the apex of the right ventricle. This permitted calculations of multiple ratios.

RESULTS

In the 10 normal hearts, the moderator band took origin at a mean ratio of 0.48 (SD 0.16) of the ventricular length. On the basis of the angiographic findings, we identified 2 basic forms of double-chambered right ventricle. In 9 patients, the obstructive muscular shelf was positioned low and diagonally across the apical component, with a mean ratio of 0.38 relative to the ventricular length (SD 0.02). In the other 11 patients, the obstructive shelf was high and horizontal, with a mean ratio of 0.27 (SD 0.02). The difference was statistically significant (P =.001). Surgical repair was performed successfully in all 26 patients through a right ventriculotomy.

CONCLUSIONS

Double-chambered right ventricle is the consequence of a high or low muscular division of the apical component of the right ventricle. The abnormal muscular bundle probably represents accentuated septoparietal trabeculations, rather than always being an abnormal moderator band.

Which two ventricles cannot be used for a biventricular repair? Echocardiographic assessment

BACKGROUND

A variety of factors can influence the suitability of a congenitally malformed heart for biventricular repair, including size, morphology, function, and dimensions and function of the inflow and outflow, among others. Although certain features have been identified that may indicate a lower probability of successful biventricular repair, our ability to predict whether a particular patient will be able to tolerate completely separate in-series systemic and pulmonary circulations remains imperfect.

METHODS AND RESULTS

In this review, we discuss the echocardiographic evaluation of various factors that can influence a patient's suitability for two ventricle repair. We call on our own experience, and illustrate our discussion with a number of echocardiographic images.

CONCLUSIONS

In most cases, echocardiography allows for full assessment of the anatomic and functional features that influence whether a patient is a suitable candidate for biventricular repair. Although a number of indices have been developed for determining who can and cannot be expected to undergo successful two ventricle repair, there remains substantial room for progress in this area.

Echocardiography of hypoplastic ventricles

BACKGROUND

Evaluation of hypoplastic ventricles with echocardiography requires an appreciation of the ultrasound methods used to assess ventricles of normal size. In this review, we present an overview of the most common techniques used to measure ventricular size, which may be analyzed as long- or short-axis dimension, area, volume, or mass. In addition to methods for evaluation, we review pertinent studies of sonographic evaluation of hypoplastic ventricles in consideration of their suitability for biventricular repair.

METHODS AND RESULTS

Standard methods of volumetric and functional evaluation of the right and left ventricles are described, with a focus on their suitability for and applicability to the patient with a small ventricle. When applied to the patient with a hypoplastic ventricle, assessment may be more complicated in some respects, and requires consideration of functional characteristics of the ventricle itself, as well as the size and function of the corresponding atrioventricular valve.

CONCLUSIONS

Echocardiography allows for excellent evaluation of ventricular size, morphology, and function. This holds true in patients with a hypoplastic ventricle as well, although the task is somewhat more complicated in such patients.

Evaluation of regional differences in right ventricular systolic function by acoustic quantification echocardiography and cine magnetic resonance imaging

BACKGROUND

Accurate quantitative evaluation of right ventricular (RV) function has been limited by its complex structural geometry. Although embryological and anatomic observations suggest that the RV is composed of 2 distinct components, the RV sinus and infundibulum, most studies on RV dimensions and function viewed it as a single chamber. This study was designed to determine the volumes, relative contribution to global systolic function, and temporal course of contraction and relaxation of the RV sinus and infundibulum.

METHODS AND RESULTS

Thirty-one individuals without heart disease (aged 1 month to 17 years, 16 boys and 15 girls) participated in this study. Instantaneous area over time, its derivatives, and the temporal course of contraction and relaxation were studied by acoustic quantification echocardiography and phonocardiography in 20 individuals. Global and regional RV volumes and ejection fraction were determined by cine MRI in 11 individuals. The RV sinus made up 81+/-6% of the combined RV end-diastolic volume and 87+/-4% of the combined stroke volume. The infundibulum accounted for the remaining 19+/-6% and 13+/-4%, respectively (P<0.0001). Compared with the infundibulum, the extent of RV sinus fiber shortening was significantly greater: for ejection fraction (56+/-11% versus 38+/-13%, P<0.001), fractional area change (42+/-14% versus 28+/-9%, P<0.0001), and dA/dt (27+/-17% versus 13+/-6%, P<0.0001). Analysis of temporal course of contraction and relaxation (expressed as percentage of the cardiac cycle to adjust for differences in heart rate) showed that the infundibulum follows the RV sinus: onset of contraction 53%+/-14 versus 19+/-11% of systole, time to peak systole 115+/-16% versus 97+/-19% (P< or =0.01), indicating a peristalsis-like pattern of contraction and relaxation.

CONCLUSIONS

The results of this study demonstrate significant regional differences between the sinus and infundibulum components of the RV with regard to contribution to stroke volume, extent of fiber shortening, and sequence of mechanical activation. These data from normal individuals can be used in future research on RV function in pathological conditions.

Development of a double-chambered right ventricle after repair of tetralogy of Fallot

OBJECTIVES

We sought to determine the frequency, etiology and progressive nature of midcavity obstruction in patients after primary repair of tetralogy of Fallot (TOF).

BACKGROUND

Midcavity obstruction (double-chambered right ventricle [DCRV]) represents a significant portion of reoperations in patients who have had TOF repair. This group is still poorly defined.

METHODS

A retrospective review of clinical, echocardiographic and catheterization data for all patients with TOF who later underwent reoperation for DCRV was performed.

RESULTS

Between 1973 and 1995, 552 children <2 years of age underwent primary TOF repair (median age 6.7 months). Long-term follow-up (median 50 months) was available in 308 children. Of these, 17 children subsequently developed DCRV requiring reoperation. The median age at initial operation was 7.9 months. During a median follow-up interval of 43.2 months, murmur intensity increased in all patients, and the average subpulmonary gradient at catheterization increased from 24+/-10 to 80+/-27 mm Hg in seven children (p = 0.002) and at Doppler echocardiography from 14+/-16 to 89+/-18 mm Hg in five children (p = 0.002). Before reoperation, 6 of the 17 children were symptomatic. During the operation (median age 55.4 months), obstruction was relieved by incision of hypertrophied anomalous muscle bundles in all 17 patients, with prominent fibrosis noted in 8 patients. Excessive septal and parietal hypertrophy was noted in one child. No new transannular patches were required. Recurrent obstruction has reappeared in 3 of these 17 children during follow-up.

CONCLUSIONS

DCRV is a medium-term complication of TOF repair in infants, with a minimal incidence of 3.1% (95% CI 1.8% to 4.9%). The condition is progressive and is due to anomalous muscle bundle hypertrophy or fibrosis, or both, which may represent displaced insertion of a moderator band. Further reobstruction does occur; continued careful follow-up is therefore essential.

Demonstration of double-chambered right ventricle on myocardial perfusion SPECT

A 19-year-old man with a double-chambered right ventricle (DCRV) and an associated ventricular septal defect was admitted to the hospital for surgical correction. Preoperative study of myocardial perfusion with Tc-99m tetrofosmin SPECT depicted the two chambers of the right ventricle. There was a substantial differential in the radioactive uptake between these two chambers. The inflow and outflow chambers with different peak-pressures (94 and 18 mm Hg) showed different uptakes reflecting the pressure difference, which was intense in the inflow chamber and weak in the outflow.

Implication of anterior septal malalignment in isolated ventricular septal defect

OBJECTIVE

The aim was to define the long term prognosis of isolated ventricular septal defect (VSD) with anteriorly malaligned outlet septum.

DESIGN

Cohort study.

SETTING

University hospital, tertiary medical care centre.

PATIENTS

Between July 1986 and June 1993, 63 patients were studied with an isolated VSD and anteriorly malaligned outlet septum (59 perimembranous; 4 muscular outlet).

MAIN OUTCOME MEASURES

The diagnosis of septal malalignment, aneurysmal transformation, right ventricular obstruction, subaortic ridge, and aortic valve prolapse was based on echocardiographic criteria, then confirmed by angiography in 33 patients and by surgery in 28. An actuarial curve for each event was obtained by Kaplan-Meier non-parametric analysis and the significance was examined by log-rank test.

RESULTS

Aneurysmal transformation decreased the size of the VSD in 52% of the patients, but was also associated with the appearance of subaortic ridge (p < 0.05). Progressive obstruction in the right ventricle was observed in 51%, more often in those without aneurysmal transformation (p < 0.05). Aortic valve prolapse was quite common whether or not aneurysmal transformation occurred (33% and 23%, respectively). This was attributed to the location of the VSD and the anterior malalignment of the outlet septum. Surgery was performed in 28 patients at a median age of 50 months because of significant left to right shunt (n = 5), or the development of obstruction in right ventricle (n = 9), aortic valve prolapse (n = 3), or combinations (n = 11). The presence of subaortic ridge per se was not considered to be a surgical indication.

CONCLUSIONS

Anteriorly malaligned VSDs have variable presentation. Careful echocardiographic evaluation is needed to identify various combinations of progressive right ventricular obstruction, aneurysmal transformation, subaortic ridge, or aortic valve prolapse. In extreme cases a patient may have a pathology complex comprising right ventricular outflow obstruction, subaortic ridge, aortic valve prolapse, and anteriorly malaligned VSD.

Color flow Doppler in the diagnosis of double-chambered right ventricle: a demographic and echocardiographic study

The purpose of this study was to evaluate the demographic and echocardiographic data of patients diagnosed with double-chambered right ventricle and attempt to explain a perceived rise in the incidence.

DEFINITION

Double-chambered right ventricle (DCRV) is a division of the right ventricle into two chambers by a hypertrophied muscle bundle.

METHODS

The medical records of patients diagnosed with DCRV were reviewed, and demographic, echocardiographic, and catheterization data were tabulated. Annual incidence of DCRV, based on year of birth, was compared to yearly detection rate, based on year of DCRV diagnosis. To evaluate the influence of color flow Doppler on the frequency of diagnosis of DCRV, demographics of patients born prior to September 1986 (when utilization of color Doppler began in our institution) were compared to those born after that date.

RESULTS

Despite an unchanged annual incidence of DCRV, yearly detection rate of this lesion rose significantly following the introduction of color flow Doppler to our institution (September 1986). DCRV was diagnosed earlier and was accompanied by earlier catheterization, which also showed lower right ventricular body gradients after September 1986. Associated anomalies, both cardiac and noncardiac, in our population differed from those reported in previous series.

CONCLUSION

This study infers that the advent of color flow Doppler significantly enhanced the diagnosis of DCRV in our pediatric patients and led to a perceived rise in incidence.