Comprehensive MRI assessment of the cardiovascular responses to food ingestion in Fontan physiology

Q: What is the clinical evidence from this study?

Study design: Observational. Population: Fontan physiology (n=30). Intervention: Standardized high-calorie liquid meal vs. Healthy controls. Primary outcome: Postprandial changes in regional vascular impedance (Z0) and blood flow.

Q: What does this research mean for the field?

Fontan patients show preserved postprandial increases in cardiac output but exhibit blunted vasoreactivity in the legs and celiac axis compared to healthy controls. Novelty: ClaimNovelty.NOVEL_FINDING. Consensus alignment: ConsensusAlignment.NEUTRAL.

Jakob A. Hauser; Alexander Jones; Bejal Pandya; Andrew M. Taylor; Vivek Muthurangu

doi:10.1152/ajpheart.00500.2020

August 28, 2020AJP Heart and Circulatory PhysiologyOpen Access

Comprehensive MRI assessment of the cardiovascular responses to food ingestion in Fontan physiology

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Key result

Fontan patients show preserved postprandial cardiac output but blunted leg and celiac vasoreactivity vs controls.

n=30

Why the study?

Does a high-calorie meal challenge alter regional and global hemodynamics differently in Fontan patients compared to healthy controls?

Study Design

Type

Observational (n=30)

Multicenter

No

Structured PICO

Does a high-calorie meal challenge alter regional and global hemodynamics differently in Fontan patients compared to healthy controls?

P

Population

30 participants (n=15 Fontan patients recruited from a cardiac outpatient clinic, n=15 healthy controls from local hospital staff), 40% women and 60% men, median age 27.6 years in Fontan group and 32.1 years in control group. 80% of Fontan patients had total cavopulmonary connection with an extracardiac conduit. Exclusion criteria included chronic diseases requiring hospital management (in controls), hepatic or renal comorbidity, history of arrhythmia, MRI-incompatible implants, residual aortic coarctation, and significant vessel lesions.

I

Intervention

High-calorie liquid meal challenge (170 mL double cream and 45 g maltose syrup; 925 kcal, fat 81 g, glucose equivalent 43 g) consumed orally in 1-2 minutes.

C

Comparator

Healthy controls receiving the identical high-calorie liquid meal challenge.

O

Outcome

Changes in mean arterial pressure (MAP), cardiac output (CO), blood flow in major aortic branches, and regional vascular impedance (Z0) over approximately 50 minutes post-meal, measured by continuous hemodynamic MRI.surrogate

Fontan patients exhibit blunted celiac and lower limb vasoreactivity in response to a meal, which may reflect compensatory mechanisms to maintain vital organ perfusion in the setting of univentricular physiology.

Limitations

Did not assess blood flow redistribution from arms, inferior mesenteric artery, bronchial arteries, or aortopulmonary collaterals.
Supine position during MRI could have influenced cardiac loading conditions.
Central venous pressure was not measured noninvasively, so vascular resistance was estimated using vascular impedance (Z0).
Assumed mean arterial pressure was constant throughout examined body compartments.
Small sample size may have been underpowered to detect weaker signals in other compartments.
Supine position during MRI could have influenced cardiac loading conditions
Central venous pressure was not measured noninvasively, so true vascular resistance was not assessed
Assumption that MAP is constant throughout examined body compartments
Potential confounding by undetected vascular lesions
Study may have been underpowered to detect weaker signals in some compartments

Implication

Hypothesis-generating for postprandial hemodynamics in Fontan circulation; prospective studies needed before clinical implications.

Abstract

Novel data on cardiovascular physiology in response to a meal in Fontan patients are presented. Using a previously validated dynamic MRI protocol, we demonstrated that the usual increase in cardiac output and the dilation of the superior mesenteric artery are preserved in clinically well Fontan patients. In contrast, vasoconstriction of the legs may have prevented redistribution of blood flow from this region in response to the meal. This may also affect responses to other types of stress. Celiac vasodilation was also absent in Fontan patients. This may be due to abnormal hepatic circulation. The proposed protocol may be used to study Fontan complications secondary to abnormal regional hemodynamics.

Discussion

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Cite This Study

Hauser et al. (2020) conducted an observational in Fontan physiology (n=30). Standardized high-calorie liquid meal vs. Healthy controls was evaluated on Postprandial changes in regional vascular impedance (Z0) and blood flow. Fontan patients showed preserved postprandial increases in cardiac output but exhibited blunted vasoreactivity in the legs and celiac axis compared to healthy controls.

synapsesocial.com/papers/6a157cf215658026c0826d1b https://doi.org/10.1152/ajpheart.00500.2020

Topics

Congenital heart disease adults

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Comprehensive MRI assessment of the cardiovascular responses to food ingestion in Fontan physiology

Study Design

Structured PICO

Limitations

Implication

Abstract

Discussion

Cite This Study

Topics

Comprehensive MRI assessment of the cardiovascular responses to food ingestion in Fontan physiology

Study Design

Structured PICO

Limitations

Implication

Abstract

Discussion

Cite This Study

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