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

2020 ◽  
Vol 319 (4) ◽  
pp. H808-H813
Author(s):  
Jakob A. Hauser ◽  
Alexander Jones ◽  
Bejal Pandya ◽  
Andrew M. Taylor ◽  
Vivek Muthurangu
Keyword(s):  
Mesenteric Artery ◽  
Dynamic Mri ◽  
Cardiovascular Responses ◽  
Cardiovascular Physiology ◽  
Food Ingestion ◽  
Hepatic Circulation ◽  
Regional Hemodynamics ◽  
Mri Protocol ◽  
Fontan Physiology ◽  
Fontan Patients

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.

Regional hemodynamic and baroreflex effects of endothelin in rats

1989 ◽  
Vol 257 (3) ◽  
pp. H918-H926 ◽  
Author(s):  
M. M. Knuepfer ◽  
S. P. Han ◽  
A. J. Trapani ◽  
K. F. Fok ◽  
T. C. Westfall
Keyword(s):  
Sympathetic Nerve ◽  
Sympathetic Nerve Activity ◽  
Pressor Response ◽  
Cardiovascular Responses ◽  
Nerve Activity ◽  
Anesthetized Rats ◽  
Pressor Responses ◽  
Regional Hemodynamics ◽  
Potent Vasoconstrictor ◽  
Baroreceptor Reflex Control

Endothelin is a peptide with potent, long-lasting pressor effects characterized by increases in mesenteric and hindquarters vascular resistance and bradycardia following an initial, transient depressor response. This study examined the mechanisms of action of endothelin on regional hemodynamics in conscious, freely moving rats and on baroreflex sensitivity both in conscious and chloralose-anesthetized rats. The pressor response to endothelin (0.67 nmol/kg) was attenuated by nifedipine (25 micrograms/kg) and augmented by chloralose anesthesia. The bradycardia was attenuated by pentolinium (10 mg/kg), atropine methyl sulfate (0.5 mg/kg), or chloralose anesthesia. Hindquarter vaso-constriction was attenuated by nifedipine, pentolinium, and atropine, whereas mesenteric vasoconstriction was less sensitive to blockade. The vasopressin V1 antagonist, [d(CH2)5Tyr(Me)]-AVP (20 micrograms/kg), indomethacin (5 mg/kg), or verapamil (150 micrograms/kg) did not affect any of these cardiovascular responses. Renal sympathetic nerve activity was reduced similarly in chloralose-anesthetized rats to pressor responses elicited by either phenylephrine or endothelin, and the slope of the baro-reflex function curve after endothelin was similar to that of phenylephrine. These results suggest that endothelin is a potent vasoconstrictor in which its action on visceral and skeletal muscle vasculature is mediated by somewhat different mechanisms. Endothelin does not alter baroreceptor reflex control of sympathetic nerve activity or heart rate.

PGE1-induced intestinal secretion: mechanism of enhanced transmucosal protein efflux.

1979 ◽  
Vol 236 (6) ◽  
pp. E788
Author(s):  
D N Granger ◽  
J S Shackleford ◽  
A E Taylor
Keyword(s):  
Blood Flow ◽  
Mesenteric Artery ◽  
Plasma Proteins ◽  
Structural Damage ◽  
Prostaglandin E1 ◽  
Intestinal Secretion ◽  
Fluid Exchange ◽  
Tissue Samples ◽  
Volume Absorption ◽  
Regional Hemodynamics

The effects of local intra-arterial prostaglandin E1 (PGE1) infusion on net transmucosal volume and protein fluxes, lymphatic volume and protein fluxes, and regional hemodynamics were ascertained in autoperfused segments of cat ileum. After acquiring control values (and tissue samples) for the various parameters, PGE1 (5.0 microgram/min) was infused directly into the superior mesenteric artery. The PGE1 infusions resulted in dramatic increases in ileal lymphatic volume and protein fluxes and blood flow. Infusion of PGE1 caused a reversion of net mucosal volume absorption to net secretion and an increased loss of plasma proteins into the lumen. Ultrastructural analysis of tissue samples taken during the PGE1 infusion indicate major structural damage to the mucosal membrane. The physiological and ultrastructural data acquired in this study suggest that 1) the increased transmucosal protein efflux during intra-arterial PGE1 infusions results from an alteration in mucosal transcapillary fluid exchange and 2) a significant portion of PGE1-induced ileal secretion is passively mediated.

Integrated cardiovascular physiology: a laboratory exercise.

1993 ◽  
Vol 265 (6) ◽  
pp. S20 ◽  
Author(s):  
R D Patil ◽  
S V Karve ◽  
S E DiCarlo
Keyword(s):  
Heart Transplantation ◽  
Cardiovascular Function ◽  
Cardiovascular Responses ◽  
Physiological Data ◽  
Special Populations ◽  
Cardiovascular Physiology ◽  
Hemodynamic Responses ◽  
Laboratory Exercise ◽  
Sedentary Individual

Examining the hemodynamic responses to exercise provides a unique opportunity to analyze and integrate cardiovascular physiology because more is learned about how a system operates when it is forced to perform than when it is idle. We designed a laboratory exercise that examines the cardiovascular responses to exercise in a sedentary individual, an athlete, an individual with quadriplegia, and an individual with heart transplantation. The special populations were chosen because of their unique limitations and adaptations, which directly influence cardiovascular function. Basic anatomic and physiological data about the special populations are provided, and the students are challenged to analyze and assimilate information from figures, answer questions, make calculations, and plot graphs. The answers to the questions are provided in the APPENDIX. This laboratory exercise should be attempted in a group to foster discussions and interactions. The laboratory does not require any equipment or software. This exercise should be attempted after the cardiovascular section of the physiology course so that the students can integrate and apply the information presented during the course.

scholarly journals Case of placental insufficiency and premature delivery in a Fontan pregnancy: physiological insights and considerations on risk stratification

Open Heart ◽  
2021 ◽  
Vol 8 (1) ◽  
pp. e001211
Author(s):  
Maria Victoria Ordoñez ◽  
Giovanni Biglino ◽  
Massimo Caputo ◽  
Brenda Kelly ◽  
Aarthi Mohan ◽  
...  
Keyword(s):  
Complex Case ◽  
Premature Delivery ◽  
Histopathological Analysis ◽  
Left Heart ◽  
Hypoplastic Left Heart ◽  
Pregnancy Status ◽  
Fontan Physiology ◽  
Essential Knowledge ◽  
Left Heart Syndrome ◽  
Fontan Patients

ObjectivesThe coexistence of two complex physiologies such as Fontan and pregnancy is still not fully understood. We aim to add a unique and essential knowledge to help our colleagues in the management of Fontan patients that undergo pregnancy as well as the fetus and the placenta perfusion.Methods and resultsWe analyse the coexistence of Fontan and pregnancy physiology on a complex case of a woman with hypoplastic left heart syndrome palliated with a univentricular repair who became pregnant, delivered very prematurely and had atypical placental findings.ConclusionHistopathological analysis of the placenta could help us to refine the understanding of Fontan physiology adaptation during pregnancy, predict women and fetal outcomes as well as to plan a better pre-pregnancy status. However, further evidence is needed in order to reach a more solid and unified conclusion.

scholarly journals Muscle metaboreflex activation via postexercise ischemia as a tool for teaching cardiovascular physiology for undergraduate students

2019 ◽  
Vol 43 (1) ◽  
pp. 34-41
Author(s):  
André L. Teixeira ◽  
Milena Samora ◽  
Lauro C. Vianna
Keyword(s):  
Blood Pressure ◽  
Arterial Blood Pressure ◽  
Neural Control ◽  
Cardiovascular Responses ◽  
Cardiovascular Regulation ◽  
Cardiovascular Physiology ◽  
Isometric Handgrip ◽  
Muscle Metaboreflex ◽  
Arterial Blood ◽  
Laboratory Class

The cardiovascular responses to exercise are mediated by several interactive neural mechanisms, including central command, arterial baroreflex, and skeletal muscle mechano- and metaboreflex. In humans, muscle metaboreflex activation can be isolated via postexercise ischemia (PEI), which increases sympathetic nerve activity and partially maintains the exercise-induced increase in arterial blood pressure. Here, we describe a practical laboratory class using PEI as a simple and useful technique to teach cardiovascular physiology. In an undergraduate exercise physiology class ( n = 47), a traditional 4-h lecture was conducted discussing the neural control mechanisms of cardiovascular regulation during exercise. Thereafter, eight students (4 men and 4 women) were selected to participate as a volunteer of a practical laboratory class. Each participant performed 90 s of isometric handgrip exercise at 40% of maximal voluntary contraction, followed by 3 min of PEI. Arterial blood pressure and heart rate were measured by digital monitors at rest and during isometric handgrip, PEI, and recovery. In addition, blood samples were collected from the tip of the exercising finger for blood lactate analyses. After the laboratory class, a survey was given to determine the perceptions of the students. The findings demonstrate that this laboratory class has proved to be highly popular with students, who self-reported a significant improvement in their understanding of several aspects of cardiovascular regulation during exercise.

Continuous monitoring of portal vein and hepatic artery hemodynamics in unrestrained rats

1988 ◽  
Vol 255 (2) ◽  
pp. G194-G200
Author(s):  
A. Braillon ◽  
M. J. Brody
Keyword(s):  
Portal Vein ◽  
Superior Mesenteric Artery ◽  
Hepatic Artery ◽  
Mesenteric Artery ◽  
Mesenteric Arteries ◽  
Hepatic Circulation ◽  
Experimental Conditions ◽  
Doppler Flowmetry ◽  
Portal Vein Flow ◽  
Large Animals

Continuous measurement of portal vein and hepatic artery blood flows during physiological experimental conditions, even in large animals, poses difficult problems. We report the successful use of miniaturized flow probes and pulsed Doppler flowmetry for chronic monitoring of hepatic artery and portal vein flows in intact unrestrained rats and describe the probe construction and implantation. Proportionality between portal vein velocity and portal flow was made possible by a technique for stabilizing the diameter of the venous segment from which velocity is recorded. The accuracy of the method in detecting changes in portal vein flow was established by the high statistically significant correlation between changes in velocity recorded simultaneously from portal vein and superior mesenteric artery in a series of rats with ligated celiac and inferior mesenteric arteries. In these preparations all portal vein flow is derived from the superior mesenteric artery. Complex dynamic changes in the hepatic circulation of conscious unrestrained rats were recorded in response to systemic injections of glucagon and angiotensin II. In the resting state several characteristic velocity patterns were recorded from the portal vein. Oscillations linked to respiration were not observed while the animals rested quietly but were noted during sleep and anesthesia. Two hitherto unrecognized patterns produced respectively by the pulsations of the superior mesenteric artery and by spontaneous contractions of the portal vein were also observed. The method described here provides the first opportunity to study hepatic circulation in chronically instrumented rats during physiological experimental conditions.

Pulmonary vasodilator therapy in the failing Fontan circulation: rationale and efficacy

2015 ◽  
Vol 25 (8) ◽  
pp. 1489-1492 ◽  
Author(s):  
Brian S. Snarr ◽  
Stephen M. Paridon ◽  
Jack Rychik ◽  
David J. Goldberg
Keyword(s):  
Single Ventricle ◽  
Fontan Operation ◽  
Vasodilator Therapy ◽  
Pulmonary Vasodilators ◽  
Pulmonary Vasodilator ◽  
Fontan Physiology ◽  
Fontan Surgery ◽  
Failing Fontan ◽  
Fontan Patients

AbstractThe Fontan operation is the final step of palliation for patients with a functionally single ventricle. Since its introduction in the 1970s, the Fontan surgery has become part of a successful surgical strategy that has improved single ventricle mortality. In recent years, we have become more aware of the limitations and long-term consequences of the Fontan physiology. Pulmonary vascular resistance plays an important role in total cavopulmonary circulation, and has been identified as a potential therapeutic target to mitigate Fontan sequelae. In this review, we will discuss the results of different pulmonary vasodilator trials and the use of pulmonary vasodilators as a treatment strategy for Fontan patients.

Impact of peak respiratory exchange ratio on the prognostic power of symptoms-limited exercise testing using Bruce protocol in patients with Fontan physiology

2020 ◽  
pp. 1-8
Author(s):  
Jianli Niu ◽  
Aliana Godoy ◽  
Talya Kadish ◽  
Bibhuti B. Das
Keyword(s):  
Oxygen Consumption ◽  
Exercise Testing ◽  
Respiratory Exchange Ratio ◽  
Peak Oxygen Consumption ◽  
Cardiopulmonary Exercise ◽  
Bruce Protocol ◽  
Fontan Physiology ◽  
The Impact ◽  
Fontan Patients

Abstract Objectives: We evaluated the impact of peak respiratory exchange ratio on the prognostic values of cardiopulmonary exercise variables during symptoms-limited incremental exercise tests in patients with Fontan physiology. Methods: Retrospective single-centre chart review study of Fontan patients who underwent exercise testing using the Bruce protocol between 2014 and 2018 and follow-up. Results: A total of 34 patients (age > 18 years) had a Borg score of ≥7 on the Borg 10-point scale, but only 50% of patients achieved a peak respiratory exchange ratio of ≥ 1.10 (maximal test). Peak oxygen consumption, percent-predicted peak oxygen consumption, and peak oxygen consumption at the ventilatory threshold was reduced significantly in patients with a peak respiratory exchange ratio of < 1.10. Peak oxygen consumption and percent-predicted peak oxygen consumption was positively correlated with peak respiratory exchange ratio values (r = 0.356, p = 0.039). After a median follow-up of 21 months, cardiac-related events occurred in 16 (47%) patients, with no proportional differences in patients due to their respiratory exchange ratio (odds ratio, 0.62; 95% CI: 0.18–2.58; p = 0.492). Multivariate Cox proportional hazard analysis showed percent-predicted peak oxygen consumption, peak heart rate, and the oxygen uptake efficient slope were highly related to the occurrence of events in patients only with a peak respiratory exchange ratio of ≥ 1.10. Conclusions: The value of peak cardiopulmonary exercise variables is limited for the determination of prognosis and assessment of interventions in Fontan patients with sub-maximal effort. Our findings deserve further research and clinical application.

scholarly journals Angiopoietin-2 predicts morbidity in adults with Fontan physiology

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Aditya S. Shirali ◽  
Gentian Lluri ◽  
Pierre J. Guihard ◽  
Miles B. Conrad ◽  
Helen Kim ◽  
...  
Keyword(s):  
Predictive Value ◽  
Single Ventricle ◽  
Superior Vena ◽  
Vena Cava ◽  
Protein Profiling ◽  
Septal Defects ◽  
History Of ◽  
Fontan Physiology ◽  
Angiopoietin 2 ◽  
Fontan Patients

AbstractMorbidity in patients with single-ventricle Fontan circulation is common and includes arrhythmias, edema, and pulmonary arteriovenous malformations (PAVM) among others. We sought to identify biomarkers that may predict such complications. Twenty-five patients with Fontan physiology and 12 control patients with atrial septal defects (ASD) that underwent cardiac catheterization were included. Plasma was collected from the hepatic vein and superior vena cava and underwent protein profiling for a panel of 20 analytes involved in angiogenesis and endothelial dysfunction. Ten (40%) of Fontan patients had evidence of PAVM, eighteen (72%) had a history of arrhythmia, and five (20%) were actively in arrhythmia or had a recent arrhythmia. Angiopoietin-2 (Ang-2) was higher in Fontan patients (8,875.4 ± 3,336.9 pg/mL) versus the ASD group (1,663.6 ± 587.3 pg/mL, p < 0.0001). Ang-2 was higher in Fontan patients with active or recent arrhythmia (11,396.0 ± 3,457.7 vs 8,118.2 ± 2,795.1 pg/mL, p < 0.05). A threshold of 8,500 pg/mL gives Ang-2 a negative predictive value of 100% and positive predictive value of 42% in diagnosing recent arrhythmia. Ang-2 is elevated among adults with Fontan physiology. Ang-2 level is associated with active or recent arrhythmia, but was not found to be associated with PAVM.

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