Open AccessPressure‐volume analysis in athyroid patients off and on thyroxine supplementation: a pilot study
Author(s) -
B. Bastos Marcelo,
Massolt Elske T.,
Kam Boen L. R.,
Peeters Robin P.,
Van Mieghem Nicolas M.,
Visser W. Edward,
Uil Corstiaan A.
Publication year - 2018
Publication title -
physiological reports
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.918
H-Index - 39
ISSN - 2051-817X
DOI - 10.14814/phy2.13883
Subject(s) - preload , medicine , afterload , levothyroxine , stroke volume , contractility , cardiology , interquartile range , heart rate , blood pressure , euthyroid , hemodynamics , endocrinology , thyroid
Thyroid hormone importantly affects the cardiovascular system. However, evaluation of stroke volume ( SV ) and its determinants is confounded by variations in volume status that occur along different thyroid states. This study applied the pressure‐volume ( PV ) framework to obtain relatively load‐independent estimates of cardiac function in hypothyroidism as compared to euthyroidism. Ten athyroid patients were assessed echocardiographically after 4 weeks in deep hypothyroid state, and again after supplementation with oral Levothyroxine ( LT 4) for 3 months. Thyroid hormone levels were assessed and noninvasive pressure‐volume ( PV ) analysis based on dedicated repeated echocardiograms was performed. Changes were assessed using paired tests. Results are presented as medians and interquartile ranges. Hypothyroidism was associated with reduced stroke volume ( SV : 67.6 ± 17 vs. 75.7 ± 20.6 mL , P = 0.024), preload (end‐diastolic volume, EDV : 122.6 ± 32.5 vs. 135.7 ± 33.6 mL , P = 0.004), and contractility (end‐systolic elastance, E es : 1.7 ± 0.33 vs. 2.58 ± 1.33 mmHg/ mL , P = 0.01). Afterload was constant (effective arterial elastance, E a : 1.66 ± 0.32 vs. 1.79 ± 0.52 mmHg/ mL , P = 0.43) and the total energy spent was lower ( PVA ∙ HR : 86.7 ± 28 vs. 110.9 ± 32.1 J, P = 0.04). Hemodynamic manifestations of frank hypothyroidism in humans are characterized by reduced preload and contractility, and unchanged total afterload. LT 4 therapy increased work efficiency and heart rate, but not the net energy expenditure. Noninvasive PV analysis may be useful to follow‐up different thyroid states.