Clinical Investigation
Fetal and Pediatric Echocardiography
Impact of Right Ventricular Geometry and Left Ventricular Hypertrophy on Right Ventricular Mechanics and Clinical Outcomes in Hypoplastic Left Heart Syndrome

https://doi.org/10.1016/j.echo.2019.06.003Get rights and content

Highlights

  • “Apical bulging” describes a specific phenotype of hypoplastic left heart syndrome.

  • Apical bulging is consistent with lateral hypertrophy of the residual left ventricle.

  • Regional dysfunction is pronounced compared with the nonbulging phenotype.

  • Transplant-free survival in reduced RV function with apical bulging is low.

Background

Right ventricular (RV) function is a major determinant of survival in hypoplastic left heart syndrome (HLHS). However, the relation of RV geometry to myocardial mechanics and their relation to transplant-free survival are incompletely characterized.

Methods

We retrospectively studied 48 HLHS patients from the Hospital for Sick Children, Toronto, (median age, 2.2; interquartile range, 3.62 years) at different surgical stages. Patients were grouped by the presence (n = 23) or absence (n = 25) of RV “apical bulging” defined as a sigmoid-shaped septum with the RV leftward apical segment contiguous with the left ventricular (LV) lateral wall. Regional and global RV strain were measured using speckle-tracking echocardiography, and regional strains were analyzed for patterns and peak values. These were compared between HLHS anatomical subtypes and between patients with versus without apical bulging. We further investigated the association between RV geometry and dysfunction with the outcomes of heart failure, death, or transplant.

Results

RV global (–7.3% ± 2.8% vs –11.2% ± 4.4%; P = .001), basal septal (–3.8% ± 3.2% vs –11.4% ± 5.8%; P = .0001) and apicolateral (–5.1% ± 3.5% vs –8.0% ± 5.8%, P = .001) longitudinal strain were lower in patients with versus without apical bulging, respectively. Apical bulging was equally prevalent in all HLHS anatomical variants. Twenty of 22 (91%) patients with apical bulging displayed hypertrophy of the LV apical and lateral segments. Death or transplantation were approximately equal in both groups but related to reduced RV global strain in patients with (seven of seven) and not in those without apical bulging (two of eight; P = .022).

Conclusions

These results suggest that the finding of apical bulging is related to the presence of a hypertrophied hypoplastic LV, with a negative impact on regional and global RV function. Therefore, analysis of RV and LV geometry and mechanics may aid in the assessment and prognostication of this high-risk population.

Section snippets

Methods

The institutional research ethics board approved this study with waiver of informed consent. We retrospectively identified children from the Hospital for Sick Children in Toronto with HLHS from our institutional database between 2008 and 2010.12 For this study, classic HLHS was defined as usual atrial arrangement, atrioventricular and ventricular-arterial concordance, and an LV deemed too small to support the systemic circulation leading to single-ventricle palliation.21 Patients at all stages

Results

Forty-eight infants and children with HLHS (median age, 0.75 years; range, 0-14 years; interquartile range, 3.62 years; mean, 2.2 years) were retrospectively analyzed. Table 1 shows their clinical characteristics, prevalence and severity of TR, and different anatomical variants of HLHS separately for apical bulging versus nonapical bulging. There was no significant difference in clinical parameters between these groups. All patients underwent a Blalock- Taussig- shunt or hybrid procedure, and

Discussion

The major findings of the study are (1) the definition of an “apical bulging” HLHS phenotype, which is related to apicolateral hypertrophy of the hypoplastic LV; (2) the association of this phenotype with more pronounced regional dysfunction and lower global RV strain compared with the nonapical bulging phenotype; and (3) the discovery that transplant or death were related to reduced RV function in the apical bulging group.

Conclusion

Apical bulging of the RV in HLHS is present in association with LV lateral wall and apical hypertrophy. Apical bulging is associated with reduced basal septal and RV global longitudinal strain, possibly due to the impact of abnormal interventricular interaction with a hypertrophied residual LV. The combination of apical bulging with low RV strain appears to be associated with transplant or death. Indeed, transplant or death occurred in most cases in patients with reduced RV strain associated

Acknowledgments

The study was supported by a research grant from the national health organization of North Norway “Helse Nord” (grant no. HNF1342-17).

References (32)

  • J. Schlangen et al.

    Does left ventricular size impact on intrinsic right ventricular function in hypoplastic left heart syndrome?

    Int J Cardiol

    (2013)
  • N.S. Khoo et al.

    Novel insights into RV adaptation and function in hypoplastic left heart syndrome between the first 2 stages of surgical palliation

    JACC Cardiovasc Imaging

    (2011)
  • T. Azakie et al.

    Evolving strategies and improving outcomes of the modified norwood procedure: a 10-year single-institution experience

    Ann Thorac Surg

    (2001)
  • J. Rychik et al.

    Perinatal and early surgical outcome for the fetus with hypoplastic left heart syndrome: a 5-year single institutional experience

    Ultrasound Obstet Gynecol

    (2010)
  • J.S. Tweddell et al.

    Improved survival of patients undergoing palliation of hypoplastic left heart syndrome: lessons learned from 115 consecutive patients

    Circulation

    (2002)
  • M.A. Walsh et al.

    Left ventricular morphology influences mortality after the Norwood operation

    Heart

    (2009)
  • Cited by (12)

    • Global Longitudinal Strain Analysis of the Single Right Ventricle: Leveling the Playing Field

      2022, Journal of the American Society of Echocardiography
      Citation Excerpt :

      As in other pediatric populations, normal values could vary on the basis of age. They likely vary by palliative stage, and there could be differences among anatomic phenotype.6,20 It is clear, however, that cited normal GLS values for a non–single right ventricle should not apply to the single right ventricle population, as many of the “normal” patients in this study would be considered abnormal by most studies.21,22

    View all citing articles on Scopus
    View full text