Augmentation of the push-pull effect by terminal aortic occlusion during head-down tilt

2003 ◽  
Vol 95 (1) ◽  
pp. 159-166 ◽  
Author(s):  
Amy L. Hakeman ◽  
Jami L. Shepard ◽  
Don D. Sheriff
Keyword(s):  
Blood Pressure ◽  
Inferior Vena Cava ◽  
Inferior Vena ◽  
Vena Cava ◽  
Vascular Occlusion ◽  
Vertical Acceleration ◽  
Sprague Dawley ◽  
Regulatory Systems ◽  
Gravitational Stress ◽  
Head Up Tilt

Tolerance to positive vertical acceleration (Gz) gravitational stress is reduced when positive Gz stress is preceded by exposure to hypogravity, which is called the “push-pull effect.” The purpose of this study was to test the hypothesis that baroreceptor reflexes contribute to the push-pull effect by augmenting the magnitude of simulated hypogravity and thereby augmenting the stimulus to the baroreceptors. We used eye-level blood pressure as a measure of the effectiveness of the blood pressure regulatory systems. The approach was to augment the magnitude of the carotid hypertension (and the hindbody hypotension) when hypogravity was simulated by head-down tilt by mechanically occluding the terminal aorta and the inferior vena cava. Sixteen anesthetized Sprague-Dawley rats were instrumented with a carotid artery catheter and a pneumatic vascular occluder cuff surrounding the terminal aorta and inferior vena cava. Animals were restrained and subjected to a control gravitational (G) profile that consisted of rotation from 0 Gz to 90° head-up tilt (+1 Gz) for 10 s and a push-pull G profile consisting of rotation from 0 Gz to 90° head-down tilt (-1 Gz) for 2 s immediately preceding 10 s of +1 Gz stress. An augmented push-pull G profile consisted of terminal aortic vascular occlusion during 2 s of head-down tilt followed by 10 s of +1 Gz stress. After the onset of head-up tilt, the magnitude of the fall in eye-level blood pressure from baseline was -20 ± 1.3, -23 ± 0.7, and -28 ± 1.6 mmHg for the control, push-pull, and augmented push-pull conditions, respectively, with all three pairwise comparisons achieving statistically significant differences ( P < 0.01). Thus augmentation of negative Gz stress with vascular occlusion increased the magnitude of the push-pull effect in anesthetized rats subjected to tilting.

scholarly journals 5-HT causes splanchnic venodilation

2017 ◽  
Vol 313 (3) ◽  
pp. H676-H686 ◽  
Author(s):  
Bridget M. Seitz ◽  
Hakan S. Orer ◽  
Teresa Krieger-Burke ◽  
Emma S. Darios ◽  
Janice M. Thompson ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Inferior Vena Cava ◽  
Portal Vein ◽  
Superior Mesenteric Vein ◽  
Inferior Vena ◽  
Vena Cava ◽  
Receptor Protein ◽  
Mesenteric Vein

Serotonin [5-hydroxytryptamine (5-HT)] causes relaxation of the isolated superior mesenteric vein, a splanchnic blood vessel, through activation of the 5-HT7 receptor. As part of studies designed to identify the mechanism(s) through which chronic (≥24 h) infusion of 5-HT lowers blood pressure, we tested the hypothesis that 5-HT causes in vitro and in vivo splanchnic venodilation that is 5-HT7 receptor dependent. In tissue baths for measurement of isometric contraction, the portal vein and abdominal inferior vena cava relaxed to 5-HT and the 5-HT1/7 receptor agonist 5-carboxamidotryptamine; relaxation was abolished by the 5-HT7 receptor antagonist SB-269970. Western blot analyses showed that the abdominal inferior vena cava and portal vein express 5-HT7 receptor protein. In contrast, the thoracic vena cava, outside the splanchnic circulation, did not relax to serotonergic agonists and exhibited minimal expression of the 5-HT7 receptor. Male Sprague-Dawley rats with chronically implanted radiotelemetry transmitters underwent repeated ultrasound imaging of abdominal vessels. After baseline imaging, minipumps containing vehicle (saline) or 5-HT (25 μg·kg−1·min−1) were implanted. Twenty-four hours later, venous diameters were increased in rats with 5-HT-infusion (percent increase from baseline: superior mesenteric vein, 17.5 ± 1.9; portal vein, 17.7 ± 1.8; and abdominal inferior vena cava, 46.9 ± 8.0) while arterial pressure was decreased (~13 mmHg). Measures returned to baseline after infusion termination. In a separate group of animals, treatment with SB-269970 (3 mg/kg iv) prevented the splanchnic venodilation and fall in blood pressure during 24 h of 5-HT infusion. Thus, 5-HT causes 5-HT7 receptor-dependent splanchnic venous dilation associated with a fall in blood pressure. NEW & NOTEWORTHY This research is noteworthy because it combines and links, through the 5-HT7 receptor, an in vitro observation (venorelaxation) with in vivo events (venodilation and fall in blood pressure). This supports the idea that splanchnic venodilation plays a role in blood pressure regulation.

scholarly journals “The Way to a Man’s Heart” - Adrenocortical Carcinoma With Vascular Invasion Into the Right Atrium and Ventricle

2021 ◽  
Vol 5 (Supplement_1) ◽  
pp. A983-A984
Author(s):  
Hassaan B Aftab ◽  
Kaye-Anne L Newton ◽  
Vitaly Kantorovich
Keyword(s):  
Blood Pressure ◽  
Adrenal Gland ◽  
Inferior Vena Cava ◽  
Right Atrium ◽  
Adrenal Mass ◽  
Inferior Vena ◽  
Vena Cava ◽  
History Of ◽  
The Right ◽  
Right Hepatic Vein

Abstract Background: Adrenocortical carcinoma (ACC) is a rare aggressive malignant neoplasm which may present with intravascular extension into the inferior vena cava (IVC) and rarely into the right atrium (RA). Clinical Case: 62-year-old male with no prior known significant medical history presented to ED with 2-day history of mild hematuria with 3-week history of headache. Vital signs were normal other than blood pressure of 198/88 while physical exam was unremarkable. Headache subsided and blood pressure improved to 130/60 range after IV labetalol administration. CT abdomen and pelvis with contrast revealed a large right suprarenal mass extending into the right hepatic vein, IVC, and RA. The right adrenal gland was not visualized while the left adrenal gland and bilateral kidneys were normal. MRI chest, heart and abdomen with contrast showed heterogeneously enhancing lobulated right adrenal mass measuring 11.4 x 11 x 14 cm (AP, transverse, CC, respectively) with extensive tumor thrombus invading the right hepatic vein, IVC, RA and notably protruding into the right ventricle (RV) through the tricuspid valve during diastole. Technitium-99m MDP whole body scan did not show any uptake suspicious for metastases. Pre-op lab assessment showed mildly abnormal 1 mg dexamethasone suppression test but no evidence of ACTH suppression, elevated catecholamines or excess adrenal steroidogenesis. He underwent combined cardiothoracic and abdominal surgery on cardiopulmonary bypass with resection of adrenal mass, removal of thrombus from IVC, RA, RV and patch angioplasty of IVC with bovine pericardium. Pathology report was consistent with ACC (AJCC stage III). On 1 month postoperative follow-up, patient is clinically doing well with plans to start mitotane with addition of etoposide/doxorubicin/cisplatin (EDP) chemotherapy. Conclusion: ACC is a rare, highly aggressive malignancy which may produce extensive intravascular invasion. It may rarely extend to the RA and even rarer into the RV; with 42 and 1 reported cases, respectively. No study has conclusively found that vascular extension of ACC is a poor prognostic factor, hence surgical management is the primary strategy including cases with RA/RV involvement. There is lack of data and consensus regarding adjuvant or palliative medical therapy. However, in phase II trials combination of EDP chemotherapy and mitotane have shown response rates ranging from 11% to 54%. Reference: Alghulayqah, Abdulaziz, et al. “Long-term recurrence-free survival of adrenocortical cancer extending into the inferior vena cava and right atrium: Case report and literature review.” Medicine 96.18 (2017).

scholarly journals Sex-related decrease in [Ca2+]i signaling and Ca2+-dependent contraction in inferior vena cava of female rat

2010 ◽  
Vol 298 (1) ◽  
pp. R15-R24 ◽  
Author(s):  
Yin Xia ◽  
Raouf A. Khalil
Keyword(s):  
Inferior Vena Cava ◽  
Inferior Vena ◽  
Varicose Veins ◽  
Vena Cava ◽  
Free Calcium ◽  
Female Rat ◽  
Sprague Dawley ◽  
Male And Female ◽  
Venous Function ◽  
The Right

Sex differences in the incidence of varicose veins have been suggested; however, the venous mechanisms involved are unclear. We hypothesized sex-related differences in venous function and underlying distinctions in intracellular free calcium, [Ca2+]i, signaling and Ca2+-dependent mechanisms of venous contraction. Circular segments of inferior vena cava (IVC) from male and female Sprague-Dawley rats were suspended between two hooks, labeled with fura-2, and placed in a cuvet inside a spectrofluorometer for simultaneous measurement of isometric contraction and the 340/380 fluorescence ratio (indicative of [Ca2+]i). In male IVC, phenylephrine (PHE; 10−5 M) caused significant increase in contraction and [Ca2+]i. In female IVC, PHE-induced contraction was significantly reduced, but [Ca2+]i did not differ significantly from males. Membrane depolarization by KCl (96 mM), which stimulates Ca2+ influx, caused parallel increases in contraction and [Ca2+]i in male IVC, and the KCl-induced contraction was significantly reduced in parallel with [Ca2+]i in female IVC. In male IVC stimulated with 0 Ca2+ KCl solution, the addition of increasing concentrations of extracellular Ca2+ ([Ca2+]e) (0.1, 0.3, 0.6, 1, and 2.5 mM) caused stepwise increases in contraction and [Ca2+]i, and both the KCl-induced [Ca2+]e-contraction curve and the [Ca2+]e-[Ca2+]i curve were reduced in female IVC, suggesting reduced Ca2+ entry via voltage-gated channels. The PHE-induced [Ca2+]e-contraction curve was significantly reduced in females, but the [Ca2+]e-[Ca2+]i curve was similar in female and male IVC, suggesting the involvement of other mechanisms in addition to Ca2+ entry. The [Ca2+]e-contraction and [Ca2+]e-[Ca2+]i curves were used to construct the [Ca2+]i-contraction relationship. The KCl-induced [Ca2+]i-contraction relationship was superimposed in male and female IVC. In contrast, the PHE-induced [Ca2+]i-contraction relationship was reduced and located to the right in female compared with male IVC, suggesting reduced [Ca2+]i sensitivity of the venous contractile myofilaments. The reduced contraction, [Ca2+]i, and [Ca2+]i sensitivity in female veins render them more prone to dilation. These sex-specific reductions in venous function, if they also occur in human veins, may play a role in the greater incidence of varicose veins in females.

Heparin-free continuous vena-venous hemofiltration as a veno-venous bypass in inferior vena cava reconstruction

Vascular ◽  
2016 ◽  
Vol 24 (4) ◽  
pp. 355-360
Author(s):  
Sha-Xi Ouyang ◽  
Jia Fu ◽  
Ji-Tong Liu ◽  
Wen-Jian Shi ◽  
Kang-Han Liu
Keyword(s):  
Blood Pressure ◽  
Inferior Vena Cava ◽  
Inferior Vena ◽  
Venous Pressure ◽  
Urine Volume ◽  
Vena Cava ◽  
Blood Platelet ◽  
Central Venous ◽  
Serum Cystatin ◽  
Venous Bypass

Objective This paper investigated the effects of continuous vena-venous hemofiltration on inferior vena cava reconstruction. Method Totally, 11 patients were observed, vascular access in right internal jugular vein and femoral vein catheterization was established guided by ultrasound, and heparin-free continuous vena-venous hemofiltration was used to substitute for extracorporeal veno-venous bypass. Furthermore, blood pressure, central venous pressure, urine volume, blood platelet, serum albumin, renal function, serum cystatin C, CRP, TBil, AST, ALT, serum amylase, serum lipase, PLT, PT, APTT, Fig, D-mier, and adverse events were determined. Results All operations were completed successfully. Average time of continuous vena-venous hemofiltration was 2.96 ± 0.76 h. No hematoma and blood leakage was occurred when catheters were inserted, and no luminal stenosis and catheter-related infections were observed. Visceral congestion was observed when the inferior vena cava was clamped, but significantly improved immediately after the continuous vena-venous hemofiltration was begun. No hemofilter was changed due to clotting during continuous vena-venous hemofiltration therapy. Blood pressure, central venous pressure, and urine volume of the patients maintained stable. No significant change was observed in blood platelet, serum albumin, and serum creatinin. Serum cystatin and hsCRP increased after operation, but still in normal level. Conclusion Heparin-free continuous vena-venous hemofiltration was an effective mode as veno-venous bypass in the treatment of inferior vena cava interruption and reconstruction.

Norepinephrine transporter inhibition alters the hemodynamic response to hypergravitation

2008 ◽  
Vol 104 (3) ◽  
pp. 756-760 ◽  
Author(s):  
Sebastian Strempel ◽  
Christoph Schroeder ◽  
Ruth Hemmersbach ◽  
Andrea Boese ◽  
Jens Tank ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Sympathetic Activity ◽  
Norepinephrine Transporter ◽  
Standing Position ◽  
Vertical Acceleration ◽  
Short Term ◽  
Double Blind ◽  
Gravitational Stress ◽  
Head Up Tilt

Sympathetically mediated tachycardia and vasoconstriction maintain blood pressure during hypergravitational stress, thereby preventing gravitation-induced loss of consciousness. Norepinephrine transporter (NET) inhibition prevents neurally mediated (pre)syncope during gravitational stress imposed by head-up tilt testing. Thus it seems reasonable that NET inhibition could increase tolerance to hypergravitational stress. We performed a double-blind, randomized, placebo-controlled crossover study in 11 healthy men (26 ± 1 yr, body mass index 24 ± 1 kg/m2), who ingested the selective NET inhibitor reboxetine (4 mg) or matching placebo 25, 13, and 1 h before testing on separate days. We monitored heart rate, blood pressure, and thoracic impedance in three different body positions (supine, seated, standing) and during a graded centrifuge run (incremental steps of 0.5 g for 3 min each, up to a maximal vertical acceleration load of 3 g). NET inhibition increased supine blood pressure and heart rate. With placebo, blood pressure increased in the seated position and was well maintained during standing. However, with NET inhibition, blood pressure decreased in the seated and standing position. During hypergravitation, blood pressure increased in a graded fashion with placebo. With NET inhibition, the increase in blood pressure during hypergravitation was profoundly diminished. Conversely, the tachycardic responses to sitting, standing, and hypergravitation all were greatly increased with NET inhibition. In contrast to our expectation, short-term NET inhibition did not improve tolerance to hypergravitation. Redistribution of sympathetic activity to the heart or changes in baroreflex responses could explain the excessive tachycardia that we observed.

Postural changes in venous pressure gradients in anesthetized monkeys

1993 ◽  
Vol 264 (1) ◽  
pp. H21-H25 ◽  
Author(s):  
N. Terada ◽  
T. Takeuchi
Keyword(s):  
Inferior Vena Cava ◽  
Inferior Vena ◽  
Superior Vena ◽  
Venous Pressure ◽  
Vena Cava ◽  
Pressure Gradients ◽  
Anatomic Structure ◽  
Postural Changes ◽  
Hydrostatic Load ◽  
Head Up Tilt

We examined the hypothesis that head-up and head-down tilt produce a symmetrical hydrostatic load on the veins. Venous pressure was measured in anesthetized monkeys with a transducer-tipped catheter. Changes in venous pressure gradients during head-up tilt corresponded to changes in hydrostatic load. However, changes in venous pressure gradients during head-down tilt were not symmetrical to those during head-up tilt. During head-down tilt, venous pressure in the superior vena cava rose, venous pressure around the right atrium did not change, and venous pressure in the inferior vena cava on the caudal side of the diaphragm rose considerably. The venous pressure of the inferior vena cava caudal to the renal vein then gradually decreased. The inferior vena cava passes through the central tendon of the diaphragm. Thus, during head-down tilt, the gravitational shift of venous blood is impeded by this anatomic structure, and venous pressure around the hepatic vein increases significantly. These data disproved our hypothesis that head-up and head-down tilt induced symmetrical but opposite influences on vena caval pressures.

Hemodynamic significance of the carotid rete during changes in arterial blood pressure

1988 ◽  
Vol 254 (5) ◽  
pp. R770-R775
Author(s):  
G. Dieguez ◽  
A. L. Garcia-Villalon ◽  
B. Gomez ◽  
S. Lluch
Keyword(s):  
Blood Pressure ◽  
Blood Flow ◽  
Smooth Muscle ◽  
Inferior Vena Cava ◽  
Inferior Vena ◽  
Vena Cava ◽  
Brain Vessels ◽  
Afferent Limb ◽  
Active Relaxation ◽  
Arterial Blood

We attempted to characterize in the goat the hemodynamic response of the carotid rete during large, passive changes in blood pressure in the afferent limb of the rete produced by mechanical constriction of the thoracic aorta or the inferior vena cava. Experiments in 12 anesthetized goats demonstrated that calculated resistance through the rete decreases in hypertension and increases in hypotension, whereas changes in resistance through brain vessels follow opposite directions. The consequence of this is that the carotid rete, by passively decreasing its resistance to blood flow in hypertension, acts as a flow-facilitating system in a situation in which smooth muscle of brain vessels contracts in response to stretch. Contrariwise, by increasing its resistance to blood flow during systemic hypotension, the carotid rete "limits" the passage of blood when active relaxation of brain vessels takes place.

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