Pressure–volume loop-derived cardiac indices during dobutamine stress: a step towards understanding limitations in cardiac output in children with hypoplastic left heart syndrome

James Wong, Kuberan Pushparajah, Adelaide de Vecchi, Bram Ruijsink, Gerald F. Greil, Tarique Hussain, Reza Razavi

Research output: Contribution to journalArticlepeer-review

11 Scopus citations

Abstract

Background Children with a single systemic right ventricle, such as in hypoplastic left heart syndrome (HLHS), frequently experience reduced exercise capacity. Elucidating the causes could help with optimising treatment strategies. Methods Prospective data from 10 consecutive symptomatic patients with HLHS undergoing clinical cardiac magnetic resonance with catheterisation (XMR) were analysed. Mean age 8.6 years (range 3.5–11.6 years), mean time since Fontan completion 5.5 years. MR-compatible catheters were placed in the systemic right ventricle and branch pulmonary arteries to record pressures at rest, with dobutamine infusion at 10 mcg/kg/min and at 20 mcg/kg/min. Cine short-axis stacks of the ventricle were performed at each condition and used to construct pressure–volume loops. Results Compared to rest, cardiac index increased with low-dose dobutamine (p < 0.01) with no further rise at peak stress despite a further, albeit, blunted rise in heart rate (p = 0.002). A fall in stroke volume occurred (p = 0.014) despite good contractility (74% increase, p = 0.045) and a well-coupled ventriculo-arterial ratio. End-diastolic pressure and early active relaxation, markers of diastolic function, were normal at rest. However, preload fell at peak stress (p < 0.008) while pulmonary vascular resistance (PVR) was low throughout. This group of HLHS patients demonstrated a fall in SV at peak stress, coinciding with a fall in preload. Conclusions Markers of systolic and diastolic function remained normal. Failure to adequately fill the ventricle implies a ceiling of maximal flow through the Fontan circuit despite low PVR.

Original languageEnglish (US)
Pages (from-to)439-446
Number of pages8
JournalInternational Journal of Cardiology
Volume230
DOIs
StatePublished - Mar 1 2017

Keywords

  • Catheterisation
  • Congenital heart disease
  • Fontan procedure
  • Hypoplastic left heart syndrome
  • Magnetic resonance imaging

ASJC Scopus subject areas

  • Cardiology and Cardiovascular Medicine

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