Immediate impact of successful percutaneous mitral valve commissurotomy on echocardiographic measures of right ventricular contractility.

BACKGROUND: Functional analysis of the right ventricle cannot be reliably evaluated by conventional echocardiography, because of its complex geometry and load dependence of ejection phase indices. The Tei index, dP/dt, and myocardial acceleration during isovolumic contraction are parameters of right ventricular (RV) contractility unaffected by RV geometry. However, the effect of loading conditions on these parameters is controversial. The aim of this study was to examine how afterload reduction observed after percutaneous transverse mitral commissurotomy (PTMC) in patients with mitral stenosis affects these measures of RV contractility. METHODS: Fifty-eight patients (mean age, 30.0 ± 8.3 years seven men, 52 women) with isolated rheumatic mitral stenosis, eight of whom had atrial fibrillation, were studied prospectively before and 24 to 48 hours after PTMC. RESULTS: Immediately after PTMC, mitral valve area increased from 1.0 ± 0.2 to 1.8 ± 0.3 cm(2) (P = .0001). There was a significant decrease in systolic pulmonary artery pressure from 50.2 ± 26.9 to 33.2 ± 12.3 mm Hg (P = .0001), a decrease in the RV Tei index from 0.5 ± 0.2 to 0.3 ± 0.2 (P = .0001), and an increase in RV dP/dt from 321.0 ± 59.9 to 494.6 ± 139.5 mm Hg/sec (P = .0001). RV myocardial acceleration during isovolumic contraction and systolic velocity at the lateral tricuspid annulus assessed by Doppler tissue imaging did not change. There were weak positive correlations among the Tei index, dP/dt, and systolic pulmonary artery pressure before PTMC (respectively, r = 0.39, r = 0.28, and P = .02, P = .05) but not afterward (respectively, r = 0.17, r = 0.02, and P = .20, P = .90). CONCLUSIONS: This study suggests that RV dP/dt and Tei index are weakly load dependent, whereas myocardial acceleration during isovolumic contraction is unaffected by acute change in RV afterload.

Failure of the GORE HELEX atrial septal defect occluder to treat membranous VSDs in swine.

OBJECTIVE: We tested the suitability of the GORE HELEX septal occluder for closure of membranous ventricular septal defect in three Yucatan minipigs that had naturally-occurring membranous ventricular septal defects. METHODS: The animals were studied in the Gore Science Center Laboratory in Flagstaff, Arizona. In all of the device implantations, seating of the right disk along the right ventricular septum was problematic with resultant entanglement of one device in the chordae tendinae during attempted removal, implantation of one device onto the tricuspid valve papillary muscle and unlocking of one device occurring after implantation. CONCLUSIONS: A new occluder design appears to be needed to minimize the risk of disk entanglement with cardiac structures, particularly within the right ventricle. These studies did establish that the Yucatan mini swine are an acceptable and appropriate model for evaluating occluders intended for closure of membranous ventricular septal defects.

Successful surgical closure of an arterial duct in 18 children in a third world country.

OBJECTIVES: To perform surgical closure of a clinically significant arterial duct on children in a third world country. BACKGROUND: An arterial duct is one of the most common congenital cardiac defects. Large arterial ducts can cause significant pulmonary overcirculation, causing symptoms of congestive cardiac failure, ultimately resulting in premature death. Closure of an arterial duct is usually curative, allowing for a normal quality of life and expectancy. In western countries, arterial duct closure in children is usually performed by deployment of a device through a catheter-based approach, replacing previous surgical approaches. In third world countries, there is limited access to the necessary resources for performing catheter-based closure of an arterial duct. Consequently, children with an arterial duct in a third world country may only receive palliative care, can be markedly symptomatic, and often do not survive to adulthood. METHODS: We assembled a team of 11 healthcare workers with extensive experience in the medical and surgical management of children with congenital cardiac disease. In all, 21 patients with a history of an arterial duct were screened by performing a comprehensive history, physical, and echocardiogram at the Angkor Hospital for Children in Siem Reap, Cambodia. RESULTS: A total of 18 children (eight male and ten female), ranging in age from 10 months to 14 years, were deemed suitable to undergo surgery. All patients were symptomatic, and the arterial ducts ranged in size from 4 to 15 millimetres. Surgical closure was performed using two clips, and in four cases with the largest arterial duct, sutures were also placed. All patients had successful closure without any significant complications, and were able to be discharged home within 2 days of surgery. Of note, four children with arterial ducts died in the 5 months before our arrival. CONCLUSION: Surgical closure of an arterial duct can be performed safely and effectively by an experienced paediatric cardiothoracic surgical team on children in a third world country. We hope that our experience will inspire others to perform similar missions throughout the world.

Echocardiographic determinants of successful balloon dilation in pulmonary atresia with intact ventricular septum.

AIMS: Pulmonary atresia with intact ventricular septum (PA-IVS) is a complex congenital heart malformation with multitude therapeutic approaches. Recently, balloon valvotomy has been used as an alternative to primary surgery. This study aimed to identify echocardiographic markers of balloon dilation success in PA-IVS. METHODS AND RESULTS: The echocardiograms of 26 patients diagnosed with PA-IVS who underwent primary pulmonary balloon valvotomy were reviewed. Tricuspid annulus Z-score, pulmonary annulus Z-score, right ventricular (RV) to left ventricular (LV) length ratio, RV to LV transverse diameter ratio, and tricuspid valve (TV) to mitral valve (MV) annulus diameter ratio were measured. The tricuspid Z-score, pulmonary Z-score, RV/LV length ratio, RV/LV diameter ratio, and the TV/MV ratio were significantly different in the group which had successful balloon dilation compared with that failed. Based on decision trees using the Weka classifier package, only RV/LV diameter ratio >0.76 predicts a 92.3% success rate. In contrast, an RV/LV diameter ratio < or =0.76 associated with RV/LV length ratio < or =0.70 predicts 100% failure. CONCLUSION: Successful balloon dilation in membranous type PA-IVS can be predicted by a scoring system using RV/LV diameter ratio and RV/LV length ratio.

Immediate impact of successful percutaneous mitral valve commissurotomy on right ventricular function.

AIMS: Mitral stenosis (MS) affects right ventricular (RV) function as a result of myocardial and haemodynamic factors. Although the long-term effects of mitral commissurotomy are well known, the aim of this study was to evaluate the immediate impact of percutaneous mitral commissurotomy (PTMC) on RV function in patients with MS. METHODS AND RESULTS: Twelve female patients (mean age 29 +/- 7 years) with isolated rheumatic MS, all in sinus rhythm, were studied before and 24-48 h after PTMC. Multiple parameters of global and longitudinal RV function were assessed by conventional and tissue Doppler imaging echocardiography. Immediately following PTMC, mitral valve area increased from 0.91 +/- 0.29 cm(2) to 1.86 +/- 0.43 cm(2) (P < 0.0001) and RV outflow tract fractional shortening (RVOTfs) increased from 57 +/- 15% to 72 +/- 12% (P = 0.002). There was a significant decrease in systolic pulmonary artery pressure from 46.4 +/- 32.1 mmHg to 29.1 +/- 13.4 mmHg (P = 0.02), in the RV Tei index from 0.44 +/- 0.025 to 0.29 +/- 0.17 (P = 0.021), in myocardial acceleration during isovolumic contraction (IVA) at the lateral tricuspid annulus from 0.36 +/- 0.11 m/s(2) to 0.25 +/- 0.07 m/s(2) (P = 0.023), and in isovolumic contraction velocities at the lateral tricuspid annulus from 11.03 +/- 3.37 cm/s to 8.50 +/- 2.04 cm/s (P = 0.034). In contrast, tissue Doppler velocities at the septal tricuspid annulus remained unchanged. The RV Tei index correlated with systolic pulmonary artery pressure before but not after PTMC (r = 0.70, P = 0.01, and r = 0.270, P = 0.053). CONCLUSION: Immediately after successful PTMC, significant decrease in RV contractility as assessed by IVA was observed whereas other parameters of infundibular and global RV function as assessed by RVOTfs and Tei index showed significant improvement. These discordant results may be related to the relative insensitivity of currently available echocardiography parameters of RV function that are not completely immune to loading conditions. Further work using larger numbers of patients is needed to confirm our findings and to assess their utility in patient follow-up and management.

Haemodialysis: effects of acute decrease in preload on tissue Doppler imaging indices of systolic and diastolic function of the left and right ventricles.

AIMS: Conventional echocardiographic (ECHO) parameters of left ventricular (LV) and right ventricular (RV) systolic and diastolic function have been shown to be load-dependent; however, the impact of preload reduction on tissue Doppler (TD) parameters of LV and RV function is incompletely understood. The aim of this study was to examine the effect of acute preload reduction by haemodialysis (HD) on conventional (ECHO) and TD imaging (TDI) indices of systolic and diastolic function of the left and right ventricles. METHODS AND RESULTS: Seventeen chronically uremic patients (age 31 +/- 10 years), without overt heart disease underwent conventional 2D and Doppler ECHO together with measurement of longitudinal mitral and tricuspid annular motion velocities. Fluid volume removed by HD was 2706 +/- 1047 cm(3). Haemodialysis led to reduction in LV end-diastolic volume (P < 0.0001), end-systolic volume (P < 0.001), peak early (E wave) transmitral flow velocity (P = 0.0001), and the ratio of early to late Doppler velocities of diastolic mitral inflow (P = 0.021). For the LV, early diastolic (E0) TDI velocities and the ratio of early to late TDI diastolic velocities (E0/A0) only on the septal side of the mitral annulus decreased significantly after HD (P = 0.0001 and P = 0.009, respectively). In a subgroup of seven patients who sustained significantly larger fluid volume loses following HD, E0 and the ratio of E0/A0 at the lateral side of mitral annulus also decreased suggesting a greater resistance of the lateral annulus to preload changes. Systolic velocities decreased after HD on both sides of mitral annulus (septal 6.90 +/- 1.10 vs. 5.97 +/- 1.48 cm/s, P = 0.006; lateral 8.68 +/- 2.67 vs. 6.94 +/- 1.52 cm/s, P = 0.011). For the RV, systolic tricuspid annular velocities decreased (13.45 +/- 1.47 vs.11.73 +/- 1.90 cm/s, P = 0.002) together with early diastolic velocities after HD (13.95 +/- 2.90 vs.10.62 +/- 2.45 cm/s, P = 0.0001). Both systolic and early diastolic tricuspid annular velocities correlated directly with fluid removal (P < 0.01). CONCLUSION: This study shows that both systolic and diastolic TDI velocities of the LV and RV are preload-dependent. However, the lateral mitral annulus is more resistant to preload changes than either the septal mitral annulus or the lateral tricuspid annulus.

Initial experience with high frequency ultrasound for the newborn C57BL mouse.

The mouse has become a powerful genetic tool for studying genes involved in cardiac development and congenital heart disease. Many of the most severe congenital heart defects are ductal-dependent, resulting in neonatal lethality. Recent advances in ultrasound technology provide an opportunity for the use of high-frequency transducers to characterize the cardiac anatomy and physiology of the newborn mouse. In this study, we define limited normative values for cardiac structure and function in the C57BL newborn mouse. Specifically, we define normal values for 19 indices derived from standard echocardiographic views. This study demonstrates that transthoracic echocardiography using a 40-MHz high-frequency transducer is a safe and reliable noninvasive modality for the delineation of cardiac anatomy and physiology in the newborn mouse.

Modified technique for the surgical treatment of severe tricuspid valve deformity in Ebstein's anomaly.

Distortion of septal and atrial anatomy in Ebstein's anomaly places the atrioventricular node and His bundle at risk for injury at operation. We present a novel technique for creating a robust neo-annulus, remote from conduction tissue, adding to the armamentarium of techniques available for the reconstruction or replacement of the tricuspid valve. Three cases are described. All the patients were in sinus rhythm, with competent native or bioprosthetic valves, at short-term follow-up.

Absent posteroinferior and anterosuperior atrial septal defect rims: Factors affecting nonsurgical closure of large secundum defects using the Amplatzer occluder.

Using transesophageal echocardiography, we sought to determine the anatomic characteristics of the secundum atrial septal defects (ASDs) that extend into the inferior sinus venosus and have no posteroinferior (PI) rim, to determine the factors related to potential closure with an Amplatzer occluder. We also sought to understand why large secundum ASDs with a PI but without an anterosuperior (AS) rim may require special techniques to reorient the left atrial disk before deployment of the waist and right atrial disk. We measured the lengths of 5 separate rims of the circumferences of 76 secundum ASDs, including anteroinferior, AS, superior, posterosuperior, and PI rims. We also measured anteroposterior and superoinferior defect diameters, total septal lengths, and the ratios of defect diameter to total septal length. The atrial depth was measured at the axial angle of the delivery sheath in 5 defects with no AS rim for which special techniques were required to achieve successful closure. Of 76 secundum ASDs, 13 (17%) had no PI rim. Each defect extended from the fossa ovalis into the inferior sinus venosus. Compared with defects with a PI rim, the factors related to potential closure included 100% larger defect diameters, shorter posterosuperior rim lengths, larger defect to total septal length ratios, and completely flat posterior atrial walls. When the AS rim was absent the factors related to the need for special techniques included diameters >/= 22 mm, atrial depth < the calculated Amplatzer occluder left atrial disk diameter, rigid wire/disk interface, and obligatory left atrial disk orientation more or less perpendicular to the atrial septal plane.

Conversion to digital technology improves efficiency in the pediatric echocardiography laboratory.

BACKGROUND: Although the videotape method (VTM) is commonly used to record and intrepret ecocardiographic images, many pediatric echocardiographers are considering acquiring to, interpreting from, and storing their images to digital disk using the single-beat digital acquisition method (SBM). The paucity of image redundancy using SBM should translate into improved laboratory efficiency compared with VTM, but hard data are lacking. The purpose of this study was to test the hypothesis that the time to acquire images to videotape using VTM and to disk using SBM would be the same for normal hearts and corresponding congenital heart diseases, but interpretation times would be shorter using SBM. METHODS: We measured the times to acquire and interpret 403 echocardiograms using standard VTM from Children's Hospital in Cincinnati, Ohio, and 352 echocardiograms acquired using SBM from Children's Hospital in San Diego, Calif. Diagnostic categories at each site included: (1) normal, (2) simple shunt or isolated valve disease, and (3) multiple-lesion disease. RESULTS: As a group, SBM echocardiograms included more hemodynamic measurements and took more time to acquire (P <.037), but less time to read (P <.001) than corresponding images acquired using VTM. Using SBM, it took more time to acquire normals and isolated valve or shunt lesions, whereas the average time to acquire multiple-lesion disease was the same using both VTM and SBM. With SBM, in contrast, interpretation times were significantly less for all corresponding diagnoses. CONCLUSION: SBM studies took longer to acquire because more hemodynamic measurements were acquired, but they were read in less time than corresponding VTM studies even though all videotapes were replayed in search fast-forward mode. Pediatric echocardiographers can increase their laboratory efficiency by converting from VTM to SBM.