effects of acute bp elevation on the vessel wall
DESCRIPTION
Effects of Acute BP Elevation on the Vessel Wall. Pathophysiology overview. Sustained neurohormonal activation and vasoconstriction leads to Endothelial decompensation Altered vascular structure. Vicious cycle of homeostatic failure begins, leading to - PowerPoint PPT PresentationTRANSCRIPT
![Page 1: Effects of Acute BP Elevation on the Vessel Wall](https://reader031.vdocuments.site/reader031/viewer/2022013004/568145be550346895db2ca03/html5/thumbnails/1.jpg)
Effects of AcuteBP Elevation onthe Vessel Wall
![Page 2: Effects of Acute BP Elevation on the Vessel Wall](https://reader031.vdocuments.site/reader031/viewer/2022013004/568145be550346895db2ca03/html5/thumbnails/2.jpg)
Pathophysiology overview
Sustained neurohormonal activation and vasoconstriction leads to • Endothelial decompensation • Altered vascular structure
Vicious cycle of homeostatic failure begins, leading to • Loss of cerebral and local autoregulation• Organ system ischemia and dysfunction• Myocardial infarction
![Page 3: Effects of Acute BP Elevation on the Vessel Wall](https://reader031.vdocuments.site/reader031/viewer/2022013004/568145be550346895db2ca03/html5/thumbnails/3.jpg)
Pathophysiology of hypertension
INAPPROPRIATELY HIGH SYMPATHETIC OUTFLOW
Increased large arterial stiffness
Inappropriately high
cardiac output
Abnormal venoconstriction
and high venous return
INAPPROPRIATELY HIGH RENIN RELEASE
ABNORMAL RENAL
SALT/WATER HANDLING
Increased systemic
resistance
Courtesy of JL Izzo Jr, MD.
![Page 4: Effects of Acute BP Elevation on the Vessel Wall](https://reader031.vdocuments.site/reader031/viewer/2022013004/568145be550346895db2ca03/html5/thumbnails/4.jpg)
NO
PGI2
CatecholaminesAT-II
ADH (vasopressin)Aldosterone
TxA2
ET1
Endogenous vasoconstrictors
The endothelium modulates vascular tone
Courtesy of JJ Ferguson III, MD.
Endogenous vasodilators
![Page 5: Effects of Acute BP Elevation on the Vessel Wall](https://reader031.vdocuments.site/reader031/viewer/2022013004/568145be550346895db2ca03/html5/thumbnails/5.jpg)
Proposed vascular pathophysiology of hypertensive urgency
Vaughan CJ, Delanty N. Lancet. 2000;356:411-7.Courtesy of JJ Ferguson III, MD.
Acute ↑ BP triggers ↑ cellular adhesion molecular expression
NO
PGI2
CatecholaminesAT-II
ADH (vasopressin)Aldosterone
TxA2
ET1( - ) ( + )
CAMs
Endogenous vasodilators
Endogenous vasoconstrictors
![Page 6: Effects of Acute BP Elevation on the Vessel Wall](https://reader031.vdocuments.site/reader031/viewer/2022013004/568145be550346895db2ca03/html5/thumbnails/6.jpg)
• Overwhelmed control of vascular tone leads to coagulation cascade activation• Loss of endothelial activity coupled with coagulation and platelets promotes DIC
Proposed vascular pathophysiology of hypertensive emergency
Vaughan CJ, Delanty N. Lancet. 2000;356:411-7. Courtesy of JJ Ferguson III, MD.
TxA2
![Page 7: Effects of Acute BP Elevation on the Vessel Wall](https://reader031.vdocuments.site/reader031/viewer/2022013004/568145be550346895db2ca03/html5/thumbnails/7.jpg)
Endothelial shear stress
Chatzizisis YS et al. J Am Coll Cardiol. 2007;49:2379-93.ESS = endothelial shear stress
Proportional to the product of blood viscosity (μ) and spatial gradient of
blood velocity at the wall (dv/dy).
![Page 8: Effects of Acute BP Elevation on the Vessel Wall](https://reader031.vdocuments.site/reader031/viewer/2022013004/568145be550346895db2ca03/html5/thumbnails/8.jpg)
Endothelial mechanoreceptors sense changes in shear stress
Chatzizisis YS et al. J Am Coll Cardiol. 2007;49:2379-93.ESS = endothelial shear stress
![Page 9: Effects of Acute BP Elevation on the Vessel Wall](https://reader031.vdocuments.site/reader031/viewer/2022013004/568145be550346895db2ca03/html5/thumbnails/9.jpg)
Shear stress rapidly activates endothelial signal transduction and gene expression
Chien S et al. Hypertension. 1998;31[part 2]:162-9.
Maximum activation
Signal Transduction
Basal activityRas
ERKJNK
0 30 60min
Ac
tiv
ati
on
Maximum activation
Gene Expression
Basal activity
C-fos mRNAMCP-1 mRNA
0 60 120min
Ac
tiv
ati
on
180 240
![Page 10: Effects of Acute BP Elevation on the Vessel Wall](https://reader031.vdocuments.site/reader031/viewer/2022013004/568145be550346895db2ca03/html5/thumbnails/10.jpg)
Definition and example of pulsatile, low, and oscillatory ESS
Chatzizisis YS et al. J Am Coll Cardiol. 2007;49:2379-93.ESS = endothelial shear stress
Cross-section
Bloodflow
Pulsatile ESS(15-70 dyne/cm2)- Direction: Unidirectional- Magnitude: Physiologic time-average
Low and oscillatory ESS(<10-12 dyne/cm2)- Direction: Bidirectional (oscillatory)- Magnitude: Low time-average
![Page 11: Effects of Acute BP Elevation on the Vessel Wall](https://reader031.vdocuments.site/reader031/viewer/2022013004/568145be550346895db2ca03/html5/thumbnails/11.jpg)
Chatzizisis YS et al. J Am Coll Cardiol. 2007;49:2379-93.
Implications of low and high shear stress
Effects of high shear stress
Endothelial dysfunction
Vascular injury
Thrombosis
Neurohumoral activation
Atherosclerosis
Plaque rupture
Effects of low shear stress
![Page 12: Effects of Acute BP Elevation on the Vessel Wall](https://reader031.vdocuments.site/reader031/viewer/2022013004/568145be550346895db2ca03/html5/thumbnails/12.jpg)
Perioperative triggers of adverse physiologic states
• Surgical trauma
• Anesthesia/analgesia
• Intubation/extubation
• Pain
• Hypothermia
• Bleeding/anemia
• Fasting
• Transfusion
Devereaux PJ et al. CMAJ. 2005;173:627-34.
Inflammatory
Hypercoagulable
Stress
Hypoxia
Physiologic state
![Page 13: Effects of Acute BP Elevation on the Vessel Wall](https://reader031.vdocuments.site/reader031/viewer/2022013004/568145be550346895db2ca03/html5/thumbnails/13.jpg)
Proposed mechanisms of perioperative MI
Devereaux PJ et al. CMAJ. 2005;173:627-34.
InflammationHypercoagulable
stateStress Hypoxia
↑TNF-α↑IL-1↑IL-6↑CRP
↑PAI-1↑Factor VIII↑Platelet reactivity↑Antithrombin III
↑Catecholamine and cortisol levels
↓Oxygen delivery
Plaque fissuring
Coronary artery shear stress
Plaque fissuring
↑BP↑HR↑FFAs↑Relative insulin
deficiency
↑Oxygen demand
Myocardial ischemia
Acute coronary thrombosis
Perioperative myocardial infarction
![Page 14: Effects of Acute BP Elevation on the Vessel Wall](https://reader031.vdocuments.site/reader031/viewer/2022013004/568145be550346895db2ca03/html5/thumbnails/14.jpg)
Summary: The pathophysiology of acute hypertensive syndromes
Mechanical stress on the vessel wall
↑BPRelease of humoral
vasoconstrictors
↑BP
Endothelial damage
Activation of the clotting cascade
Further release of humoral
vasoconstrictors
Fibrinoid necrosis of small blood
vessels
Pressure natriuresis
Volume depletion
RAAS activation
Vasopressinendothelin
catecholaminesMajor physiologic
derangements Courtesy of JJ Ferguson III, MD.
![Page 15: Effects of Acute BP Elevation on the Vessel Wall](https://reader031.vdocuments.site/reader031/viewer/2022013004/568145be550346895db2ca03/html5/thumbnails/15.jpg)
Pathophysiology of acute hypertensive syndromes: A vicious cycle
Courtesy of JJ Ferguson III, MD.
Vascular injury
Tissue ischemia
Vasoconstrictor release
![Page 16: Effects of Acute BP Elevation on the Vessel Wall](https://reader031.vdocuments.site/reader031/viewer/2022013004/568145be550346895db2ca03/html5/thumbnails/16.jpg)
Summary: Acute hypertension
Nonsurgical patients
• Little studied in past decade
• Multiple knowledge gaps– Patient characteristics– Treatment patterns– Outcomes
Perioperative patients
• Frequent finding
• Emerging data demonstrate importance of tighter BP control than currently recommended
![Page 17: Effects of Acute BP Elevation on the Vessel Wall](https://reader031.vdocuments.site/reader031/viewer/2022013004/568145be550346895db2ca03/html5/thumbnails/17.jpg)
Acute hypertension: Conclusions
• New options are needed
• Need for long-term patient follow-up in hypertensive urgencies/emergencies