Improved early ventricular performance with a right ventricle to pulmonary artery conduit in stage 1 palliation for hypoplastic left heart syndrome: evidence from strain Doppler echocardiography

Choice of shunt type for the Norwood I procedure: does it make a difference?

OBJECTIVES

This study aimed to compare pulmonary artery (PA) growth between patients who received a right ventricle-to-PA (RV-PA) shunt and those who received a modified Blalock-Taussig shunt (mBTS).

METHODS

All consecutive patients with hypoplastic left heart syndrome who underwent the Norwood I procedure between 2001 and 2017 were included in the study. Pre-stage 2 angiograms were analysed to measure the size of the PA. The Nakata index was calculated to estimate PA growth. The ratio of the right PA to left PA cross-sectional area (RPA/LPA) was used to calculate the difference in growth between the 2 branches. Study end points were shunt failure, shunt-related mortality and growth of the PAs.

RESULTS

A total of 223 patients with hypoplastic left heart syndrome (RV-PA group = 137, mBTS group = 86) underwent the Norwood I procedure, and 186 patients (RV-PA n = 116, mBTS n = 70) achieved the stage 2 procedure. PA growth was better in patients with mBTS (Nakata index: RV-PA = 282, mBTS = 315 mm2/m2, P = 0.021). LPA growth was worse compared to RPA growth in both groups (RPA/LPA: RV-PA = 1.21, mBTS = 1.29, P = 1.0). Patients with RV-PA shunts experienced more frequent shunt stenosis compared to patients with mBTS (26 vs 2, P < 0.010). Freedom from shunt failure was 83.3 ± 3.2% and 94 ± 2% at 6 months in the RV-PA and mBTS groups, respectively (P = 0.003).

CONCLUSIONS

PA growth is significantly better in patients who received an mBTS. Moreover, patients with an RV-PA shunt more frequently experienced shunt failure due to shunt stenosis. However, survival after the NW procedure is not shunt dependent and growth of the LPA is less pronounced than RPA, regardless of the shunt type.

Detection of occult right ventricular dysfunction in young Egyptians with type 1 diabetes mellitus by two-dimensional speckle tracking echocardiography

Background

Type 1 diabetes mellitus (T1DM) is a common chronic disorder of childhood and adolescence. T1DM induced cardiomyopathy has a different entity than T2DM as it relies on different pathophysiological mechanisms, and rarely coexists with hypertension and obesity. Evaluation of right ventricular (RV) function in diabetic patients has been neglected despite the important contribution of RV to the overall cardiac function that affects the course and prognosis of diabetic cardiomyopathy (DCM).

Objective

To assess RV myocardial performance in asymptomatic T1DM using speckle tracking and standard echo parameters and correlate it with functional capacity using treadmill stress test.

Patients and methods

Thirty-nine patients with TIDM (Group 1, mean age 18.2 ± 1.7y, BMI = 26.2 ± 3.9 kg/m²), without cardiac problems and 15 apparently healthy matched subjects as a control group (Group 2, mean age 18.8 ± 2.3 y, BMI = 22.8 ± 3.3 kg/m²) were enrolled. RV function was evaluated using conventional, tissue Doppler and 2D speckle tracking echocardiography (2D-STE). The peak RV global longitudinal strain (RV-GLS) was obtained. Functional capacity was assessed by treadmill exercise test and estimated in metabolic equivalent (METs).

Results

In this study; the diabetic group showed statistically highly significant decrease in the average RV-GLS (−14.0 ± 6.9 in group 1 vs. −22.7 ± 2.5 in group 2, P < 0.001), significant decrease in RV S velocity (9.5 ± 2.2 in group 1 vs. 11.5 ± 1.8 in group 2, P < 0.05), significantly reduced E/A ratio (1.0 ± 0.2 in group 1 vs. 1.1 ± 0.1 in group 2, P < 0.05), and highly significant increased E/Em ratio (7.9 ± 3.2 in group 1 vs. 5.2 ± 0.7 in group 2, P < 0.001). We did not found any significant differences between the two groups regarding the other echocardiographic or functional capacity parameters.

Conclusion

In asymptomatic patients with T1DM, in addition to RV diastolic dysfunction, early (subclinical) RV systolic dysfunction is preferentially observed with normal RV and left ventricular (LV) ejection fraction (EF). 2D-STE has the ability to detect subclinical RV systolic dysfunction.

Cavopulmonary Anastomosis During Same Hospitalization as Stage 1 Norwood/Hybrid Palliative Surgery

BACKGROUND

Limited literature has examined characteristics of infants with hypoplastic left heart syndrome (HLHS) who remain hospitalized during the interstage period. We described their epidemiologic characteristics, in-hospital outcomes, and identified risk factors that predict the need for superior cavopulmonary anastomosis (SCPA) during the same hospitalization.

METHODS

This retrospective multicenter database analysis included infants with HLHS who underwent stage 1 palliation from 2004 through 2013.

RESULTS

Among 5374 infants with HLHS, 314 (5.8%) underwent SCPA during the same hospitalization as stage 1 palliation. They had a higher incidence of baseline comorbidities, complications, and interventions than infants who were discharged. Despite an overall increase in need for SCPA in the same hospitalization across different eras, there was no significant statistical difference in mortality in the two groups in the same era. Septicemia, necrotizing enterocolitis, modified Blalock-Taussig shunt, cardiac catheterization, cardiopulmonary resuscitation, extracorporeal membrane oxygenation, gastrostomy tube, and antiarrhythmic agents were independently associated with increased odds of undergoing SCPA during the same hospitalization. Patients undergoing right ventricle to pulmonary artery shunt were less likely to remain hospitalized until stage 2 palliation. Nonsurvivors in the SCPA group had greater need for interventions and worse intensive care unit outcomes.

CONCLUSIONS

Infants with HLHS who remain hospitalized after stage 1 until their stage 2 palliation differ significantly from infants who were discharged. Several clinical characteristics, comorbidities, and need for interventions are associated with the likelihood for undergoing stage 2 palliation during the same hospitalization. Timely identification and intervention of adjustable causes of heart failure may improve outcomes.

Right ventricular systolic function in hypoplastic left heart syndrome: A comparison of manual and automated software to measure fractional area change

BACKGROUND

Quantitative echocardiographic assessment of right ventricular function is important in children with hypoplastic left heart syndrome (HLHS). The aim of this study was to examine the repeatability of different echocardiographic techniques, both manual and automated, to measure fractional area change (FAC) in patients with HLHS and to correlate these measurements with magnetic resonance imaging (MRI)-derived ejection fraction (EF).

METHODS

Fifty-one children with HLHS underwent transthoracic echocardiography and cardiac MRI under the same general anesthetic as part of routine inter-stage assessment. FAC was measured from the apical four-chamber view using three different techniques: velocity vector imaging (VVI) (Syngo USWP 3.0; Siemens Healthineers), QLAB (Q-lab R 10.0; Philips Healthcare), and manual endocardial contour tracing (Xcelera, Philips Healthcare). Intra- and inter-observer variability was calculated using intra-class correlation coefficient (ICC). FAC was correlated with MRI EF calculated using a single standard method.

RESULTS

Fractional area change had a good correlation with MRI-derived EF with an R value for VVI, QLAB, and manual methods of .7, .6, and .4, respectively. Intra- and inter-observer variability for FAC was good for automated echocardiographic methods (ICC>.85) but worse for manual method particularly inter-observer variability of FAC and end-systolic area. Both automated techniques tended to produce higher FAC values compared with manual measurements (P<.001).

CONCLUSION

Automation improves the repeatability of FAC in HLHS. There are some differences between automated software in terms of correlation with MRI-derived EF. Measurement bias and wide limits of agreement mean that the same echocardiographic technique should be used during the follow-up of individual patients.

Right ventricular performance using myocardial deformation imaging in infants with bronchopulmonary dysplasia

OBJECTIVE

Right ventricular (RV) performance among infants with bronchopulmonary dysplasia (BPD) remains poorly understood. We tested the hypothesis that myocardial deformation imaging (MDI) strain and strain rate would allow for differentiation between infants with severe and milder forms of BPD, independent of tissue Doppler imaging (TDI) and superior to conventional echocardiographic measurements.

STUDY DESIGN

Infants with various severities of BPD (11 with none or mild, 13 with moderate and 10 with severe) underwent conventional echocardiography, TDI and MDI assessments at >36 weeks of corrected gestational age. BPD severity grading was determined according to the National Institutes of Child Health and Disease workshop rating scale by physicians blinded to the echocardiogram results. Group data were compared with one-way analysis of variance or Kruskal-Wallis tests, with post hoc multiple comparisons.

RESULTS

No differences in traditional echocardiographic parameters or TDI among the three BPD severity groups were observed; none of the infants had evidence of pulmonary hypertension. Using MDI, infants with severe BPD had lower peak global systolic strain than did infants with moderate BPD (P<0.01) or mild/none BPD (P<0.01). Early and late diastolic strain rate measurements were similar across the three groups.

CONCLUSIONS

Among infants with severe forms of BPD, evidence of abnormal RV systolic function was detected with MDI, but not traditional echocardiographic or TDI measurements. Infants with severe forms of BPD may represent a particularly high-risk subgroup for decreased RV performance warranting cardiac surveillance. MDI should be considered as a method to quantitate RV function in this population.

Peri-operative assessment of right heart function: role of echocardiography

The right heart contributes significantly to overall cardiac function. Right ventricular (RV) haemodynamics and function have been defined to be physiologically different from the left ventricle, and yet independently associated with outcomes in a spectrum of conditions. In particular, RV function has been shown to influence prognosis of patients undergoing surgery. The assessment of right heart function during the intra-operative and immediate postoperative periods plays an important role in the clinical management of patients having surgery. While a number of techniques are available for the assessment of the right heart intra-operatively, echocardiography remains the prime choice being least invasive, relatively safe, readily accessible and cost-effective. Advancements in the field of echocardiographic have improved ability to assess right heart function. This review examines the role echocardiography and advances in this imaging modality in the assessment of right heart function within the peri-operative setting.

Fate of ventricular and valve performance following early bidirectional Glenn procedure after Norwood operation controlled for hypoplastic left heart syndome anatomic subtype

The Norwood operation (NO) with a right ventricle (RV)-to-pulmonary artery (PA) shunt (NRVPA) is reportedly associated with early hemodynamic advantage. Shunt strategy has been implicated in ventricular function. Outcomes after NRVPA compared with classic procedure as part of a strategy involving early bidirectional Glenn (BDG) procedure were analyzed with reference to RV, tricuspid, and neoaortic valve performance. Between January 2005 and December 2010, 128 neonates with hypoplastic left heart syndrome (HLHS) underwent NO. Controlled for aortic/mitral stenosis (AS-MS) subtype, 28 patients underwent NRVPA (group A), and 26 patients had classic procedure (group B). The patients with a non-HLHS single-ventricle anatomy and those who had undergone a hybrid approach for HLHS were excluded from the study. The mean age at NO was 6.8 ± 3.5 days in group A and 6.9 ± 3.6 days in group B. Transthoracic echocardiographic evaluation (TTE) after NO (TTE-1) at the midinterval between NO and BDG (TTE-2), before BDG (TTE-3), before Fontan (TTE-4), and at the last follow-up evaluation (TTE-5) was undertaken. Cardiac catheterization was used to assess hemodynamic parameters before the Glenn and Fontan procedures. The operative, interstage, and pre-Fontan survival rates for AS-MS after NO were respectively 88.1 % (90.3 % in group A vs. 84.7 % in group B; p = 0.08), 82.5 % (82.7 % in group A vs. 81.8 % in group B; p = 0.9), and 80.7 % (79.5 % in group A vs. 81.8 % in group B; p = 0.9). The median follow-up period was 39.6 months (interquartile range 2.7-4.9 months). The RV global function, mid- and longitudinal indexed dimensions, fractionated area change before BDG (TTE-1, TTE-2, TTE-3) and after BDG (TTE-4, TTE-5), and right ventricular end-diastolic pressure did not differ statistically between the groups (p > 0.05). No statistically significant difference in tricuspid or neoaortic intervention was found between the groups (p > 0.05). Controlled for the AS-MS HLHS subtype, shunt strategy showed no midterm survival or hemodynamic (ventricular or valve) impact. At midterm, the follow-up need for neoaortic or tricuspid valve surgical intervention was not affected by shunt selection. The structural ventricular adaptation after reversal of shunt physiology was irrespective of shunt strategy.

Ventricular performance after surgery for a congenital heart defect as assessed using advanced echocardiography: from doppler flow to 3D echocardiography and speckle-tracking strain imaging

A varying degree of impairment of ventricular performance is observed over the long-term after surgery for a congenital heart defect (CHD). Impaired ventricular performance has been shown to be of prognostic value for increased risk of cardiovascular events in adult CHD patients. This emphasizes the importance of delineating the timing and cause of this postoperative impairment. Impairment of ventricular performance could develop over time as a consequence of residua, sequelae and complications of the CHD or surgical procedure. Yet, impaired ventricular performance has also been observed immediately after surgery and can persist and/or worsen over time. This postoperative impairment of ventricular performance is the focus of this review. This article provides an overview of echocardiographic techniques currently used to assess ventricular performance. Furthermore, we review current literature describing ventricular performance, as assessed using echocardiography, after correction of a CHD. In general, a decrease in ventricular performance is observed directly after surgery for CHD’s. Subsequent follow-up of ventricular performance is characterized by a varying degree of postoperative recovery. A consistent observation is the persistent impairment of right-ventricular performance after repair in several different subgroups of CHD patients ranging from ventricular septal defect repair to surgery for Tetralogy of Fallot.

Feasibility of conductance catheter-derived pressure-volume loops to investigate ventricular mechanics in shunted single ventricles

We present pressure–volume loops obtained from two patients with single-ventricle physiology, one with a modified Blalock–Taussig shunt and one with a right ventricle-to-pulmonary artery shunt. The dissimilarities in pressure–volume loop contour and related indices highlight potentially important differences in ventricular mechanics between the shunt types.

Impact of shunt type on growth of pulmonary arteries after norwood stage I procedure: current best available evidence

The past decade has seen a substantial improvement in the outcome following surgical palliation for hypoplastic left heart syndrome. This has been attributed to modifications in the surgical as well as postoperative management strategies. One such modification is the reemergence of the right ventricle to pulmonary artery (RV-PA) shunt as an alternative to the modified Blalock-Taussig (mBT) shunt as the source of pulmonary blood flow. The RV-PA shunt has been shown to improve the immediate surgical outcome compared with the classic Norwood procedure with an mBT shunt. Despite the several reported advantages, the impact of the RV-PA shunt on growth of the pulmonary arteries and incidence of late development of central PA stenosis remains unclear. This systematic review evaluates the current best available evidence to address this issue and concludes that the evidence from retrospective studies and only available randomized controlled trial (RCT) is conflicting. The retrospective studies predominantly suggest that the Norwood procedure with RV-PA shunt may have favorable effects on the development of the pulmonary arteries due to even distribution of pulmonary blood flow with greater distal left pulmonary artery growth, resulting in more balanced distal branch pulmonary artery size albeit with a greater degree of central pulmonary artery hypoplasia needing surgical attention. On the contrary, the RCT reports that the overall size of the pulmonary artery on angiography before the stage II procedure was smaller in the RV-PA shunt group than in the mBT shunt group, with no information available on incidence of central pulmonary hypoplasia.

Does initial shunt type for the Norwood procedure affect echocardiographic measures of cardiac size and function during infancy?: the Single Vventricle Reconstruction trial

BACKGROUND

The Pediatric Heart Network trial comparing outcomes in 549 infants with single right ventricle undergoing a Norwood procedure randomized to modified Blalock-Taussig shunt or right ventricle-pulmonary artery shunt (RVPAS) found better 1-year transplant-free survival in those who received RVPAS. We sought to compare the impact of shunt type on echocardiographic indices of cardiac size and function up to 14 months of age.

METHODS AND RESULTS

A core laboratory measured indices of cardiac size and function from protocol exams: early after Norwood procedure (age 22.5 ± 13.4 days), before stage II procedure (age 4.8 ± 1.8 months), and at 14 months (age 14.3 ± 1.2 months). Mean right ventricular ejection fraction was <50% at all intervals for both groups and was higher in the RVPAS group after Norwood procedure (49 ± 7% versus 44 ± 8%; P<0.001) but was similar by 14 months. Tricuspid and neoaortic regurgitation, diastolic function, and pulmonary artery and arch dimensions were similar in the 2 groups at all intervals. Neoaortic annulus area (4.2 ± 1.2 versus 4.9 ± 1.2 cm(2)/m(2)), systolic ejection times (214.0 ± 29.4 versus 231.3 ± 28.6 ms), neoaortic flow (6.2 ± 2.4 versus 9.4 ± 3.4 L/min per square meter), and peak arch velocity (1.9 ± 0.7 versus 2.2 ± 0.7 m/s) were lower at both interstage examinations in the RVPAS compared with the modified Blalock-Taussig shunt group (P<0.001 for all), but all were similar at 14 months.

CONCLUSIONS

Indices of cardiac size and function after the Norwood procedure are similar for modified Blalock-Taussig shunt and RVPAS by 14 months of age. Interstage differences between shunt types can likely be explained by the physiology created when the shunts are in place rather than by intrinsic differences in cardiac function.

CLINICAL TRIAL REGISTRATION

URL: http://www.clinicaltrials.gov. Unique identifier: NCT00115934.

Echocardiographic evaluation of the single right ventricle in congenital heart disease: results of new techniques

Right ventricular (RV) function is increasingly recognized as having prognostic significance in various disease processes. The current gold standard for noninvasive measurement of RV function is cardiac magnetic resonance imaging; however, because of practical considerations, echocardiography remains the most often used modality for evaluating the RV. In the past, because of its complex morphology, echocardiographic assessment of the RV was usually qualitative in nature. Current advances in echocardiographic techniques have been able to overcome some of the previous limitations and thus quantification of RV function is increasingly being performed. In addition, recent echocardiographic guidelines for evaluating the RV have been published to aid in standardizing practice. The evaluation of RV function almost certainly has no greater importance than in the congenital heart population, especially in those patients that have a single RV acting as the systemic ventricle. As this complex population continues to increase in number, accurate and precise evaluation of RV function will be a major issue in determining clinical care.

Developments in echocardiographic techniques for the evaluation of ventricular function in children

Echocardiography is a very important tool for the diagnosis and follow-up of children with congenital and acquired heart disease. One of the challenges that remains in paediatric heart disease is the assessment of systolic and diastolic function in children, as this is influenced by growth, morphology and loading conditions. New echocardiographic techniques, such as tissue Doppler, deformation imaging and three-dimensional echocardiography, have great potential application in this field. They may provide new insights into the influence of growth, morphology and loading on cardiac mechanics, and could become useful clinical tools. In this review, we discuss the potential use and limitations of these new echocardiographic techniques in paediatric and congenital heart disease.

Comparison of Norwood shunt types: do the outcomes differ 6 years later?

BACKGROUND

A modification to the Norwood procedure involving a right ventricle-to-pulmonary artery (RV-PA) shunt may improve early postoperative outcomes. Concerns remain about the effect of the right ventriculotomy required with this shunt on long-term ventricular function.

METHODS

Between January 2000 and April 2005, 76 patients underwent the Norwood procedure, 35 with a modified Blalock-Taussig shunt (mBTS) and 41 with a RV-PA shunt. Patients were monitored until death or September 1, 2009, with an average follow-up of 6.8 years. Cardiac catheterization, echocardiograms, perioperative Fontan courses, and need for cardiac transplantation were compared between groups.

RESULTS

Cumulative survival was 63% (22 of 35) in the mBTS group vs 78% (32 of 41) in the RV-PA group (p = 0.14). Pre-Fontan echocardiography revealed poorer ventricular function in RV-PA patients (p = 0.03). Cardiac transplantation was required in 6 of 32 (19%) patients with a prior RV-PA shunt vs 1 of 23 (4%) in the mBTS group (p = 0.06). This results in an almost identical cumulative transplant-free survival between groups; 60% (21 of 35) in the mBTS group and 63% (26 of 41) in the RV-PA group (p = 0.95).

CONCLUSIONS

Neither shunt offers a clear survival advantage through an average follow-up of 6.8 years. The RV-PA shunt results in impaired late ventricular function that may result in an increased need for cardiac transplantation.

Two-dimensional speckle strain and dyssynchrony in single right ventricles versus normal right ventricles

BACKGROUND

Patients with single-right ventricle (RV) physiology are at increased risk for myocardial dysfunction and mechanical dyssynchrony. Newer echocardiographic modalities may be better able to quantitate right ventricular function in this unique population. The aim of this study was to use two-dimensional speckle analysis of strain and strain rate to quantify systolic function and dyssynchrony in single-RV post-Fontan patients and compare them with values for controls.

METHODS

Patients with single RV who underwent Fontan palliation and patients with normal biventricular anatomy were studied. Two-dimensional speckle echocardiography was used to measure strain, strain rate, time to peak, and longitudinal displacement in a 6-segment model of the RV. Independent t tests were used to compare group means. P values < .05 were considered significant.

RESULTS

Thirteen patients were studied in each group. There was no significant difference in age between single-RV patients and controls (6.60 +/- 2.07 vs 5.75 +/- 1.83 years, respectively). Single-RV strain values were significantly lower in all 6 segments compared with values in controls (basal interventricular septum [IVS], -14.28 +/- 7.78% vs -22.00 +/- 2.36%; mid IVS, -17.70 +/- 4.54% vs -22.99 +/- 2.71%; apical IVS, -19.46 +/- 4.97% vs -25.42 +/- 4.06%; basal RV, -22.40 +/- 5.7% vs -41.42 +/- 5.42%; mid RV, -21.20 +/- 3.21% vs -39.67 +/- 6.04%; apical RV, -20.70 +/- 4.90% vs -33.68 +/- 3.90%). Systolic strain rate and longitudinal displacement were also lower in the free wall and apical IVS in single-RV patients compared with controls. The modified Yu index for strain time to peak was longer in the single-RV patients (43.16 +/- 13.63 vs 21.72 +/- 7.25 ms).

CONCLUSION

Significant differences in strain analysis between single-RV patients and patients with biventricular physiology exist at a relatively young age. Future studies are needed to determine the clinical significance of these differences.

In hypoplastic left heart patients is Sano shunt compared with modified Blalock-Taussig shunt associated with deleterious effects on ventricular performance?

A best evidence topic in congenital cardiac surgery was written according to a structured protocol. The question addressed was: in hypoplastic left heart patients is Sano shunt compared with modified Blalock-Taussig (mBT) shunt associated with deleterious effects on ventricular performance? Sano shunt modification of Norwood procedure involves construction of a right ventricle to pulmonary artery (RV-PA) conduit as an alternative source of pulmonary blood flow. Compared with the mBT shunt, the RV-PA conduit provides a more stable haemodynamic state in the immediate postoperative period and is reported to be associated with lower interstage mortality. However, concerns regarding the impact of ventriculotomy on short- and long-term performance of single ventricle have been expressed. Altogether 101 papers were found using the reported search terms, from which seven represented the best evidence to answer the clinical question. The authors, journal, date and country of publication, patient group studied, study type, relevant outcomes and results of these papers are tabulated. None of the echocardiographic or clinical outcome studies showed poor ventricular performance after ventriculotomy of the systemic RV for construction of Sano shunt. A small autopsy study of 11 patients showed greater remodelling of the ventricular myocardial extracellular matrix in patients with RV-PA conduit with potential implications for poor ventricular performance. We conclude that the current available evidence, although weak, does not show any adverse effects of ventriculotomy on ventricular performance in patients with Sano shunt in the short- and medium-term. However, all the existing studies are limited by small numbers, non-randomised design and retrospective nature with failure of correlation of echocardiographic indices to clinical outcomes. It is expected that the Pediatric Heart Network randomised controlled trial will address this important issue.

Staged surgical palliation in hypoplastic left heart syndrome and its variants

BACKGROUND

Surgical options for infants with hypoplastic left heart syndrome (HLHS) and/or its variants are cardiac transplantation or the heart-preserving staged palliation with Norwood operation,followed by a two-staged Fontan procedure. We describe our 17-year experience with staged palliation of HLHS and/or its variants.

METHODS

Between December 1989 and December 2006, 64 patients with HLHS and/or its variants underwent a Norwood procedure (mean age/weight, 11.8+/-2.5 days/3.4 kg). Forty-four patients had classical HLHS. Twenty-eight percent had associated congenital cardiac, structural, and genetic anomalies. Subsequently, 25 patients underwent a bidirectional Glenn procedure (stage II) and 11 patients a modified Fontan procedure (stage III). Others await stage II and/or stage III. The follow-up was 143.2 patient-years.

RESULTS

Including the learning curve, overall early mortality from 1989 to 1999 after the Norwood procedure was 39.06%. This decreased tremendously for the last seven years, and reduced to 12.8% in 2000 to 2003 until 0% in 2004 to 2006 (p < 0.005). The causes of mortality were sepsis, capillary leak,or heart failure. Three patients died between stages II and III. One patient underwent heart transplantation after the second stage because of heart failure. Among 34 Norwood survivors, four are slightly tachypneic from a mild pulmonary hyperperfusion; one presents symptoms of minimal brain disease.

CONCLUSION

This report identified an outcome improvement after staged palliation of HLHS, attributed to an increase in experience and expertise gained over time. Lower operative weight, ascending aortic size, prolonged duration of cardiopulmonary bypass, and hypothermic circulatory arrest were identified to significantly influence early mortality after the Norwood procedure.

Tissue velocities, strain, and strain rate for echocardiographic assessment of ventricular function in congenital heart disease

During the last decade tissue Doppler and myocardial deformation imaging has been introduced to quantify myocardial function in patients with congenital heart disease. These methods could have potential benefits for patients where the anatomy makes it difficult to quantify ventricular function using M-mode or two-dimensional volumetric techniques. In this overview, the potential benefits as well as limitations of the techniques are discussed. Looking directly into the myocardium renders the techniques geometry-independent, allowing the quantification of right ventricular as well as univentricular systolic function. The limitations include the influence of variable loading conditions as well as different methodological problems.

Development of the pulmonary arteries after the Norwood procedure: comparison between Blalock-Taussig shunt and right ventricular-pulmonary artery conduit

BACKGROUND

The Norwood-Sano procedure for hypoplastic left heart syndrome (HLHS) has been associated with improved postoperative hemodynamics and outcome. This study compared the effect of a Blalock-Taussig shunt with right ventricular-pulmonary artery (RV-PA) conduit before bidirectional Glenn on the development of the PAs.

METHODS

Between January 2000 and June 2007, 42 patients with HLHS underwent bidirectional Glenn: 19 (mean age, 7 +/- 1.5 months) had a Blalock-Taussig shunt (3.5 mm in 15; and 4 mm in 4); 23 patients (mean age, 5 +/- 1 month) had RV-PA conduit (5-mm tube). Patients underwent postoperative cardiac catheterization and echocardiograms.

RESULTS

Total PA (Nakata) index was 192 +/- 10 mm2/m2 in the Blalock-Taussig group and 238 +/- 18 mm2/m2 in the RV-PA conduit group (p = 0.03). In the RV-PA conduit patients, the left and right PAs had comparable diameters. In the Blalock-Taussig group, the left PA was smaller than the right (p = 0.02). The mean PA pressure at the end of the operation was 14 +/- 2 mm Hg in the Blalock-Taussig group and 11 +/-1 mm Hg in the RV-PA conduit group (p = 0.06). Persistent pleural effusion occurred in 4 Blalock-Taussig patients (21%) and in 1 (4%) with RV-PA conduit (p < 0.05). Postoperative arterial oxygen saturation was 80% +/- 2% in the RV-PA conduit group and 74% +/- 2% in the Blalock-Taussig group (p < 0.05).

CONCLUSIONS

The Norwood procedure with RV-PA conduit may have favorable effects on the development of the PA due to even distribution of pulmonary blood flow.

Pathological changes and myocardial remodelling related to the mode of shunting following surgical palliation for hypoplastic left heart syndrome

BACKGROUND

The modification of placing the shunt from the right ventricle to the pulmonary arteries, also known as Sano procedure, has allegedly improved results over the short term in surgical palliation of hypoplastic left heart syndrome with the Norwood procedure. With this in mind, we reviewed autopsied specimens from neonates and children who did not survive after either a classic arterio-pulmonary shunt, or the modified procedure with the shunt placed from the right ventricle to the pulmonary arteries, so as to evaluate the pathological substrates of the remodelling of the systemic right ventricle, assessing any differences induced by the 2 techniques.

METHODS

We obtained the hearts from 11 patients with neonatal diagnosis of hypoplastic left heart syndrome who died after the first or second stages of the Norwood sequence of operations, comparing them with 6 normal hearts matched for age and weight. Macroscopic, microscopic and morphometric analysis were performed on each specimen, evaluating the diameter of the myocytes, extracellular matrix remodelling in terms of fibrosis and type of collagen, and vascularization in terms of capillary density.

RESULTS

Hypertrophy of the myocytes was significantly increased in the hearts from patients having either a classic arterio-pulmonary or the ventriculo-pulmonary modification of the shunt compared to controls (p < 0.05). Myocardial fibrosis was increased in those having a shunt placed from the right ventricle to the pulmonary arteries when compared to the other 2 groups. The ratio of collagen I to collagen III was similar in those undergoing a classic arterio-pulmonary shunt compared to controls (0.94), but was lower in those having a shunt placed from the right ventricle to the pulmonary arteries (0.61), with an increase in collagen type III. The density of capillaries was lower in those who had undergone a classic arterial shunt when compared to the others.

CONCLUSION

We have shown greater remodelling of the ventricular myocardial extracellular matrix in patients having a shunt from the right ventricle to the pulmonary arteries when compared to those having a classic arterio-pulmonary shunt, with this remodelling progressing even after the neonatal period. This may influence a later suboptimal ventricular performance.

Outcomes of surgical treatment of infants with hypoplastic left heart syndrome: an institutional experience 1983-2004

AIM

To determine outcomes of surgical treatment of infants with hypoplastic left heart syndrome (HLHS).

METHODS

Retrospective analysis of medical records of infants with HLHS.

RESULTS

129 of 206 (63%) infants with HLHS were managed surgically over the period 1983-2004. Survival from all stages of surgical repair was 52 (40%) patients with significantly different (P < 0.001) survival according to surgical techniques and post-operative intensive care management recognisable in three eras. During 1983-1995 a classical Norwood stage 1 operation with a systemic-pulmonary shunt was performed for 61 infants with 13 (21%) survivors. From 1996 to 2002, pulmonary vasoconstriction and systemic vasodilatation after stage 1 operation were used to optimise systemic blood flow yielding a survival of 22 of 46 (48%) infants. From 2002 to 2004 a ventricular-pulmonary conduit was used with survival of 17 of 22 (77%) infants. Survival at 1, 6, 12 months and at 5, 10 and 15 years was 65%, 53%, 48%, 38%, 38% and 25%, respectively. The mean +/- SD number of surgical procedures was 4.5 +/- 3.7; duration of hospitalisation 53 +/- 52 days (median 38); number of hospital admissions 3.0 +/- 3.5; duration in intensive care 18 +/- 20 days (median 11); hours of mechanical ventilation 278 +/- 398 (median 151).

CONCLUSION

Short-term survival of HLHS has improved substantially over recent years with a ventricular-pulmonary conduit while long-term survival has been mediocre after arterial systemic-pulmonary shunts. Irrespective of type of primary surgery, infants undergo many operations and spend long periods in hospital and intensive care.

Right ventricular strain and strain rate properties in patients with right ventricular myocardial infarction

BACKGROUND

This study was planned to assess strain and strain rate properties of right ventricle in patients with RV myocardial infarction.

MATERIAL AND METHOD

Thirty patients with acute inferior myocardial infarction were included in this study. The presence of right ventricular infarction in association with an inferior myocardial infarction was defined by an ST-segment elevation 0.1 mV in lead V4 R. According to this definition, 15 patients had electrocardiographic signs of inferior myocardial infarction without right ventricular infarction (group I), and 15 patients had electrocardiographic signs of inferior myocardial infarction with right ventricular infarction (group II). Echocardiography was performed using a Vivid 5 System (GE Ultrasound; Horten, Norway) and a 2.5-MHz transducer. 2-dimensional color doppler myocardial imaging (CDMI) data for longitudinal function were recorded from the RV free wall using standard apical view. Offline analysis of the myocardial color Doppler data for regional velocity (V), strain rate (Sr), and strain (S) curves was performed using a special software program (EchoPac 6.4 Vingmed, Horten, Norway). They were assessed in basal, middle and apical segments of the RV. The differences between different groups were assessed with the Mann-Whitney U-test. A value of P < 0.05 was considered statistically significant.

RESULTS

Systolic tissue velocity, strain, strain rate of basal (4.8 +/- 0.8 cm/s vs 6.5 +/- 1.2 cm/s, -12 +/- 3% vs -24 +/- 5%, 1.28 +/- 0.3/s vs -1.9 +/- 0.4/s; P < 0.001, <0.001, <0.001, respectively) and mid (4.2 +/- 0.5 cm/s vs 5.4 +/- 0.5 cm/s, -16 +/-3% vs -26 +/- 4%, -1.2 +/- 0.3/s vs -2.1 +/- 0.3/s; P < 0.001, <0.001, <0.001, respectively) segments of right ventricle were significantly lower in patients with RV infarction than in patients without RV infarction. There were no differences between groups for apical strain, strain rate, and systolic tissue velocity.

CONCLUSION

This study demonstrates that right ventricular strain and strain rate were lower in patients with left ventricular inferior wall myocardial infarction with, compared to without, right ventricular infarction.

A contemporary comparison of the effect of shunt type in hypoplastic left heart syndrome on the hemodynamics and outcome at stage 2 reconstruction

OBJECTIVE

We compare the hemodynamics and perioperative course of shunt type in hypoplastic left heart syndrome at the time of stage 2 reconstruction and longer-term survival.

METHODS

We retrospectively reviewed the echocardiograms, catheterizations, and hospital records of all patients who had a stage 1 reconstruction between January 2002 and May 2005 and performed a cross-sectional analysis of hospital survivors.

RESULTS

One hundred seventy-six patients with hypoplastic left heart syndrome and variants underwent a stage 1 reconstruction with either a right ventricle-pulmonary artery conduit (n = 62) or a modified Blalock-Taussig shunt (n = 114). The median duration of follow-up is 29.1 months (range, 0-57 months). By means of Kaplan-Meier analysis, there is no difference in survival at 3 years (right ventricle-pulmonary artery conduit: 73% [95% confidence limit, 59%-83%] vs modified Blalock-Taussig shunt: 69% [95% confidence limit, 59%-77%]; P = .6). One hundred twenty-four patients have undergone stage 2 reconstruction (78 modified Blalock-Taussig shunts and 46 right ventricle-pulmonary artery conduits). At the time of the stage 2 reconstruction, patients with right ventricle-pulmonary artery conduits were younger (153 days [range, 108-340 days]; modified Blalock-Taussig shunt, 176 days [range, 80-318 days]; P = .03), had lower systemic oxygen saturation (73% [range, 58%-85%] vs 77% [range, 57%-89%], P < .01), and had higher preoperative hemoglobin levels (15.8 g/dL [range, 13-21 g/dL] vs 14.8 g/dL [range, 12-19 g/dL], P < .01) compared with those of the modified Blalock-Taussig shunt group. By means of echocardiographic evaluation, there was a higher incidence of qualitative ventricular dysfunction in patients with right ventricle-pulmonary artery conduits (14/46 [31%] vs 9/73 [12%], P = .02). However, no difference was observed in common atrial pressure or the arteriovenous oxygen difference.

CONCLUSION

Interim analyses suggest no advantage of one shunt type over another. This report raises concern of late ventricular dysfunction and outcome in patients with a right ventricle-pulmonary artery conduit.

Effect of shunt type on echocardiographic indices after initial palliations for hypoplastic left heart syndrome: Blalock-Taussig shunt versus right ventricle-pulmonary artery conduit

OBJECTIVES

The study objective was to compare echocardiographic indices in infants with hypoplastic left heart syndrome (HLHS) randomized to different surgical pathways.

BACKGROUND

Initial surgical palliation for HLHS has evolved to two strategies that vary by source of pulmonary blood flow: a modified Blalock-Taussig (BT) shunt or a right ventricle to pulmonary artery (RV-PA) conduit.

METHODS

Seventeen patients were randomized to either a BT shunt or RV-PA as their first-stage palliation, and 15 survived through bidirectional Glenn (BDG) (seven BT shunts/eight RV-PAs). Echocardiography was performed pre-stage 1 palliation (S1P), early post-S1P, pre-BDG, and post-BDG. Echocardiographic measurements included indices of right ventricle function and shape, right ventricle myocardial performance index, neoaortic Doppler flow patterns and cardiac output, Doppler inflow and tissue imaging, and conduit/neoaortic regurgitant fraction.

RESULTS

There were no significant differences in right ventricle size, shape, or estimates of systolic and diastolic function between groups. Patterns of changes in neoaortic Doppler flow in the RV-PA conduit group showed a decrease in all indices of systemic flow early after initial palliation, but these measures consistently increase later post-S1P and post-BDG. In contrast, the BT shunt group increases these same indices post-S1P and pre-BDG with a decrease after shunt removal.

CONCLUSIONS

Right ventricle size and function do not appear significantly affected by surgical type of initial palliation for HLHS, and this correlates with early outcome. Echocardiographic Doppler findings correlate well with the expected physiologies of the different shunts as these infants progress through initial palliative strategies.

Subclinical right ventricular dysfunction in diabetes mellitus--an ultrasonic strain/strain rate study

AIMS

While left ventricular dysfunction has been recognized to be a common complication of diabetes mellitus, data regarding right ventricular (RV) performance in patients with diabetes are incomplete. The aim of the study was to determine the preclinical effects of diabetes on regional RV systolic and diastolic function in asymptomatic persons with diabetes using the echocardiographic strain/strain rate technique.

METHODS

Groups studied consisted of 33 subjects with diabetes only (DM; aged 57.3 +/- 12.9 years) and 40 subjects with coexisting diabetes and hypertension (DMHT; aged 57.5 +/- 10.5 years). In all patients with diabetes, coronary artery disease and pulmonary hypertension were excluded. Thirty-six healthy age-matched persons served as control subjects. In each patient an echocardiographic study with strain/strain rate imaging was performed. Analysis of RV deformation data included assessment of systolic strain, peak systolic strain rate (SRs) and peak early diastolic strain rate (SRe) obtained from the basal and apical segments of the RV free wall.

RESULTS

Significantly lower values of systolic strain and SRs in the basal and apical segment of the RV free wall in the DM and DMHT groups as compared with control subjects indicated impairment of RV systolic function. Similarly, decreased SRe in patients with diabetes in both RV segments examined reflected abnormalities of RV diastolic performance. The systolic defects were more pronounced in the apical than in the basal segment. All measured parameters were similar in the two groups with diabetes.

CONCLUSION

Diabetes mellitus is associated with subclinical RV systolic and diastolic dysfunction, regardless of coexisting hypertension.

Outcomes after bidirectional Glenn operation: Blalock-Taussig shunt versus right ventricle-to-pulmonary artery conduit

BACKGROUND

There are distinct physiologic differences between patients with single-ventricle lesions who have undergone the Norwood procedure with a right ventricle-to-pulmonary artery conduit (NW-RVPA) compared with those patients who have undergone the Norwood operation with a Blalock-Taussig shunt (NW-BTS). We evaluated bidirectional Glenn operation outcomes and compared the two groups to assess whether the type of Norwood operation influenced outcomes.

METHODS

A retrospective chart review compared bidirectional Glenn operation outcomes for children undergoing the Norwood operation with NW-RVPA or NW-BTS at Children's Hospital Boston from January 1, 2002, to December 31, 2003.

RESULTS

Of 80 patients undergoing the Norwood operation, 56 (NW-BTS, 27 versus NW-RVPA, 29) returned for the bidirectional Glenn operation at our institution. The NW-RVPA group had a lower median age at presentation for bidirectional Glenn (4.5 months versus 5.8 months; p = 0.01), but had better weight gain (20.6 g/day versus 16.5 g/day; p = 0.03) than the NW-BTS group. No interstage deaths occurred in the NW-RVPA group. There were no differences in morbidity or mortality after the BDG between the two groups.

CONCLUSIONS

There were no differences in morbidity and mortality outcomes after the bidirectional Glenn operation between the NW-RVPA and NW-BTS groups. Despite younger age at presentation, the NW-RVPA patients had better growth rate, which may have contributed to the similar postoperative outcomes.

Does a ventriculotomy have deleterious effects following palliation in the Norwood procedure using a shunt placed from the right ventricle to the pulmonary arteries?

INTRODUCTION

A recent modification to the Norwood procedure involving a shunt placed directly from the right ventricle to the pulmonary arteries may improve postoperative haemodynamics. Concerns remain, however, about the potential problems produced by the required ventriculotomy.

METHODS

We compared 76 patients with hypoplastic left heart syndrome who underwent the Norwood procedure, 35 receiving a modified Blalock-Taussig shunt and the remaining 41 a shunt placed directly from the right ventricle to the pulmonary arteries. We reviewed their subsequent progress through the second stage of palliation. A single observer graded right ventricular function, and the severity of tricuspid regurgitation, based on blinded review of the most recent echocardiograms prior to the second stage of palliation.

RESULTS

At the time of catheterization prior to the second stage, patients with a shunt placed from the right ventricle to the pulmonary arteries, rather than a modified Blalock-Taussig shunt, had higher arterial diastolic blood pressure, at 44 versus 40 millimetres of mercury, p equal to 0.02, lower ventricular end diastolic pressures, at 8 versus 11 millimetres of mercury, p equal to 0.0002, and larger pulmonary arteries as judged using the Nakata index, at 270 versus 188 millimetres squared per metres squared, p equal to 0.009. There was no difference in qualitative ventricular systolic function or tricuspid regurgitation between groups. No differences were found between groups during the hospitalization following the second stage of palliation. A trend towards improved survival to the second stage was seen following the construction of a shunt from the right ventricle to the pulmonary arteries.

CONCLUSIONS

Construction of a shunt from the right ventricle to the pulmonary arteries is associated with lower right ventricular end diastolic pressures, larger pulmonary arterial size, and higher systemic arterial diastolic pressures. No apparent deleterious effects of the right ventriculotomy were observed in terms of qualitative ventricular systolic function or tricuspid regurgitation.

Stage I palliation for hypoplastic left heart syndrome: Norwood versus Sano modification

PURPOSE OF REVIEW

Advancements in surgical technique and perioperative care have significantly improved the survival of infants born with hypoplastic left heart syndrome. A recent modification to the Norwood procedure is being adopted by many centers to improve postoperative hemodynamic stability and survival to stage II palliation. The late effects of this modification, however, are speculated and have not been investigated.

RECENT FINDINGS

Center-specific improved short-term outcomes have been reported in a few small, nonrandomized studies of a new approach to the Norwood procedure, which utilizes a right ventricle to pulmonary artery shunt or Sano modification to provide pulmonary blood flow rather than the standard modified Blalock-Taussig shunt.

SUMMARY

The classic Norwood procedure and Sano modification each have specific advantages and disadvantages in both the short and long term. Data comparing the two techniques are nonrandomized, contradictory, and utilize historical controls. The optimal shunt to improve survival to the second-stage palliation is unknown. A multicenter randomized clinical trial comparing the Sano with the modified Blalock-Taussig shunt in hypoplastic left heart syndrome or variants is currently in progress and should hopefully provide future guidelines for shunt selection based on clinical presentation.

Fate of pulmonary arteries following Norwood Procedure

OBJECTIVE

This study evaluated the requirement for surgical reoperation and catheter-based reintervention to central pulmonary arteries (CPAs) following Norwood Procedure (NP). We sought to identify the influence of various surgical techniques employed during NP on subsequent interventions.

METHODS

Between 1993 and 2004, 226 patients underwent Stage II following NP. Ninety-eight patients (43%) had completion of Fontan circulation (Stage III) and a further 107 (47%) are on course for Fontan completion with 21 (9%) inter-stage deaths. During NP, the aortic arch was reconstructed without additional material (n = 91, 40%) or with a pulmonary homograft patch (n = 135, 60%). Pulmonary blood flow was supplied by modified Blalock-Taussig shunt (n = 177, 78%) or right ventricle to pulmonary artery conduit (RV-PA; n = 49, 22%). The CPAs defect was closed directly (n = 69, 31%) or with a patch (n = 157, 69%). Complete resection of coarctation was performed in 126 patients (56%).

RESULTS

Ninety-seven patients (43%) required surgical reoperation to CPAs during Stage II. Actuarial freedom from reoperation was 60+/-3%, 52+/-4% and 50+/-4% at 1, 5 and 10 years, respectively. On multivariable analysis, NP with RV-PA increased risk of reoperation (LR 8.3, 5.3-13.2; p < 0.001). Forty-one patients (18%) required catheter-based reintervention on CPAs. Actuarial freedom from reintervention was 98+/-1%, 72+/-4% and 58+/-6% at 1, 5 and 10 years, respectively. CPA problems were almost exclusively limited to the proximal Left pulmonary artery. On multivariable analysis, catheter-based reintervention became more common with time. Complete resection of coarctation increased risk of reintervention (LR 3.9, 1.6-9.6; p < 0.005). Arch reconstruction and CPAs repair techniques did not affect risk of reoperation or reintervention on CPAs.

CONCLUSIONS

CPA stenoses and hypoplasia need surgical attention in approximately half of all patients undergoing the NP. The need for reoperation is increased when using the RV-PA conduit technique (although the majority of these are performed as part of the Stage II procedure). Catheter reinterventions are almost exclusively confined to the left CPA and are increased when the arch is shortened by resection of the coarctation tissue at time of NP.

Early postoperative outcomes in a series of infants with hypoplastic left heart syndrome undergoing stage I palliation operation with either modified Blalock-Taussig shunt or right ventricle to pulmonary artery conduit

OBJECTIVE

Previous publications using nonconcurrent series of patients indicate improved survival for patients with hypoplastic left heart syndrome (HLHS) undergoing stage I palliation with a right ventricle to pulmonary artery conduit (NW-RVPA) vs. a modified Blalock-Taussig shunt (NW-BT). We compared postoperative outcomes in a concurrent series of patients with HLHS undergoing an NW-BT procedure vs. NW-RVPA procedure.

DESIGN

Perioperative data from 66 consecutive patients who underwent NW-BT (n = 37) or NW-RVPA (n = 29) procedures were retrospectively analyzed.

SETTING

Cardiac intensive care unit in a tertiary pediatric hospital.

PATIENTS

Charts were reviewed for all patients with the diagnosis of HLHS undergoing the NW-BT or NW-RVPA procedure between January 2002 and December 2003.

RESULTS

Cardiopulmonary bypass time was longer in the NW-BT group than in the NW-RVPA group (152.5 +/- 52.0 vs. 134.5 +/- 36.1 mins; p = .04). Postoperative diastolic pressures were higher and the Pao2 to Fio2 ratio profiles were lower for the NW-RVPA group over the first 72 hrs. Time to sternal closure (2 [1-6] vs. 4 [2-41] days; p = .01), duration of mechanical ventilation (113 [49-386] vs. 136 [84-764] hrs; p = .01), time to establish enteral feeds (4 [2-8] vs. 5 [3-22] days; p = .01), length of intensive care unit stay (11 [7-55] vs. 15 [8-90] days; p = .04), and length of hospital stay (16 [11-67] vs. 27 [12-126] days; p = .01) were shorter in the NW-RVPA group. Postoperative mortality was not significantly different between the NW-RVPA group (7%) and NW-BT group (11%).

CONCLUSION

At an experienced institution with low stage I palliation mortality for HLHS, there were no differences in early morbidity and mortality between the NW-RVPA and NW-BT procedures. The primary advantage of the NW-RVPA procedure may be faster recovery following surgery and earlier discharge from the hospital.

Pre- and Postoperative Quantitation of Right Ventricular Tissue Doppler Velocities in Infants with Hypoplastic Left Heart Syndrome

BACKGROUND

The purpose of this study was to use tissue Doppler imaging (TDI) to serially quantitate initial and preoperative right ventricular (RV) TDI velocities and compare them to postoperative RV TDI velocities as measures of RV function in newborns with hypoplastic left heart syndrome (HLHS).

METHODS

Twelve consecutive patients were prospectively studied with diagnosis of HLHS. Systolic (Sw) and early diastolic (Ew) velocities were recorded at the tricuspid annulus and the ventricular septum at (1) admission, (2) immediately preoperative, and (3) during recovery. All patients were treated preoperatively with prostaglandins (PGE). Velocities were compared using repeated measure analysis of variance.

RESULTS

Mean age at diagnosis was 1 day (0-4 days). Time from diagnosis to surgery was 4 days (1-9 days), age at surgery 5.3 days (2-10 days), and time from surgery to postoperative echo 12.3 days (5-19 days). Tricuspid annular and septal systolic velocities increased from admission to preoperative. Both tricuspid Sw and Ew and septal Sw velocities decreased postoperatively. No significant changes occurred in the ventricular septal diastolic (Ew) velocities from admission to preoperative.

CONCLUSION

These data indicate that following the institution of PGE and initial medical and ventilatory management, there is an increase in RV annular and septal systolic velocities from the initial to the preoperative period and that these indices as well as RV annular diastolic velocities decline significantly postoperatively. Initial septal diastolic velocities were severely abnormal and did not significantly change pre- and postoperatively. These data may have significance for both postoperative and subsequent long-term RV function.

Influence of surgical strategies on outcome after the Norwood procedure

OBJECTIVE

The study objective was to identify how the evolution of surgical strategies influenced the outcome after the Norwood procedure.

METHODS

From 1992 to 2004, 367 patients underwent the Norwood procedure (median age, 4 days). Three surgical strategies were identified on the basis of arch reconstruction and source of pulmonary blood flow. The arch was refashioned without extra material in group A (n = 148). The arch was reconstructed with a pulmonary artery homograft patch in groups B (n = 145) and C (n = 74). Pulmonary blood flow was supplied by a modified Blalock-Taussig shunt in groups A and B. Pulmonary blood flow was supplied by a right ventricle to pulmonary artery conduit in group C. Early mortality, actuarial survival, and freedom from arch reintervention or pulmonary artery patch augmentation were analyzed.

RESULTS

Early mortality was 28% (n = 102). Actuarial survival was 62% +/- 3% at 6 months. Early mortality was lower in group C (15%) than group A (31%) or group B (31%; P <.05). Actuarial survival at 6 months was better in group C (78% +/- 5%) than group A (59% +/- 5%) or group B (58% +/- 4%; P <.05). Fifty-three patients (14%) had arch reintervention. Freedom from arch reintervention was 76% +/- 3% at 1 year, with univariable analysis showing no difference among groups A, B, and C (P =.71). One hundred patients (27%) required subsequent pulmonary artery patch augmentation. Freedom from patch augmentation was 61% +/- 3% at 1 year, and was lower in group C (3% +/- 3%) than group A (80% +/- 4%) or group B (72% +/- 5%; P <.05).

CONCLUSIONS

Survival after the Norwood procedure improved after the introduction of a right ventricle to pulmonary artery conduit, but a greater proportion of patients required subsequent pulmonary artery patch augmentation. The type of arch reconstruction did not affect the incidence of arch reintervention.

Longitudinal but not circumferential deformation reflects global contractile function in the right ventricle with open pericardium

The clinical evaluation of right ventricular (RV) contractility is problematic because instantaneous RV volumetry is difficult to achieve. Our aim was to test whether global RV contractility can be assessed by using regional indexes in the longitudinal and/or circumferential axis. Six anesthetized adult ewes were instrumented with a RV conductance catheter and four RV free wall sonomicrometry crystals (interrogating the longitudinal and circumferential axes). Global and regional preload recruitable stroke work (PRSW) were measured by using acute vena cava occlusions at baseline, during esmolol and dobutamine infusion, and during stable low-preload and high-afterload conditions. The agreement between regional and global PRSW was assessed with regression and Bland-Altman analysis. Both regional PRSW indexes correlated well with global PRSW in baseline conditions, during inotropic modulation (R(2) = 0.83 and 0.74 for longitudinal and circumferential regional PRSW, respectively), and during preload reduction (R(2) = 0.62 and 0.83, respectively), but only longitudinal regional PRSW correlated with global PRSW in increased afterload conditions (R(2) = 0.59 and 0.13 for longitudinal and circumferential regional PRSW, respectively). We conclude that in the open-chest, open-pericardium animal model, deformation in the longitudinal axis accurately reflects global RV contractile function in baseline conditions and during acute load modulation, whereas circumferential motion is influenced by changes in afterload.

Update on pediatric echocardiography

PURPOSE OF REVIEW

The past year was dominated by developments in echocardiographic assessment of myocardial function in children, and this paper reviews some of these major advancements in pediatric echocardiography as a guide to those interested in imaging of the pediatric heart and vascular system.

RECENT FINDINGS

Characterization of myocardial function using Doppler tissue imaging, both in the normal child and in the child with congenital or acquired heart disease, was a primary focus of pediatric echocardiographic investigation. Other new technologies, including integrated backscatter analysis and three-dimensional echocardiography, appear to hold significant promise as tools to improve myocardial assessment echocardiographically. Three-dimensional echocardiography also is developing into a powerful technique in fetal echocardiography, allowing rapid data acquisition and extensive image postprocessing with opportunities for both anatomic and functional assessment. Childhood fitness and diseases have a significant impact on the heart and vascular bed, and descriptions of echocardiographic findings in obese children, children engaged in athletic activities, children with renal disease, children who have undergone cardiac transplantation, and those with aortic valve disease were better characterized by investigations published over the past year.

SUMMARY

Pediatric echocardiography has clearly expanded from a diagnostic tool used to describe anatomic abnormalities associated with congenital heart disease to a noninvasive myocardial monitoring tool that allows serial assessment of the pathologic effects of both cardiac and noncardiac disease.

Neonates with hypoplastic left heart syndrome have ultrasound evidence of abnormal superior mesenteric artery perfusion before and after modified Norwood procedure

OBJECTIVE

To a) describe superior mesenteric artery resistive index, as an estimate of perfusion, before and after modified Norwood; and b) assess incidence of diastolic flow reversal in the superior mesenteric artery before and after modified Norwood.

DESIGN

Prospective observational trial.

SETTING

Children's hospital pediatric intensive care unit.

PATIENTS

Ten newborns with hypoplastic left heart syndrome.

INTERVENTIONS

Ultrasound documentation of superior mesenteric artery diastolic flow direction and measurement of superior mesenteric artery resistive index 24-48 hrs before and 24-48 hrs after modified Norwood.

MEASUREMENTS AND MAIN RESULTS

Seven males and three females were enrolled. There was no change between the superior mesenteric artery resistive index pre- vs. postoperatively-0.99 (95% confidence interval, 0.85, 1.12) vs. 1.07 (95% confidence interval, 1.0, 1.15) (p = .13). Incidence of retrograde diastolic blood flow in the superior mesenteric artery was not different pre- vs. postoperatively (70% vs. 50%, p = .41). No patients developed necrotizing enterocolitis and all survived to hospital discharge.

CONCLUSIONS

Ultrasound measurements in neonates with hypoplastic left heart syndrome suggest that superior mesenteric artery perfusion, as measured by resistive index, is impaired. Superior mesenteric artery diastolic flow reversal is common before and immediately after modified Norwood.

Staged surgical management of hypoplastic left heart syndrome: a single institution 12 year experience

OBJECTIVE

To describe a 12 year experience with staged surgical management of the hypoplastic left heart syndrome (HLHS) and to identify the factors that influenced outcome.

METHODS

Between December 1992 and June 2004, 333 patients with HLHS underwent a Norwood procedure (median age 4 days, range 0-217 days). Subsequently 203 patients underwent a bidirectional Glenn procedure (stage II) and 81 patients underwent a modified Fontan procedure (stage III). Follow up was complete (median interval 3.7 years, range 32 days to 11.3 years).

RESULTS

Early mortality after the Norwood procedure was 29% (n = 95); this decreased from 46% (first year) to 16% (last year; p < 0.05). Between stages, 49 patients died, 27 before stage II and 22 between stages II and III. There were one early and three late deaths after stage III. Actuarial survival (SEM) was 58% (3%) at one year and 50% (3%) at five and 10 years. On multivariable analysis, five factors influenced early mortality after the Norwood procedure (p < 0.05). Pulmonary blood flow supplied by a right ventricle to pulmonary artery (RV-PA) conduit, arch reconstruction with pulmonary homograft patch, and increased operative weight improved early mortality. Increased periods of cardiopulmonary bypass and deep hypothermic circulatory arrest increased early mortality. Similar factors also influenced actuarial survival after the Norwood procedure.

CONCLUSION

This study identified an improvement in outcome after staged surgical management of HLHS, which was primarily attributable to changes in surgical technique. The RV-PA conduit, in particular, was associated with a notable and independent improvement in early and actuarial survival.

The intensive care of infants with hypoplastic left heart syndrome

Until a little over two decades ago, hypoplastic left heart syndrome was considered an inoperable and fatal condition, with most deaths occurring in early infancy, and almost all of those affected dying before their first birthday. However, the advent of surgical palliation and advances in peri-operative care, have offered hope to these patients and their families.