Peri o perative Hypertension When Does it Matter?!

1. Perioperative HypertensionWhen Does it Matter?! Sukh Brar MD FRCPC Royal Columbian Hospital October 26th, 2013

11. 1. Definitions • 2. Prevalence • 3. Pathophysiology • 4. Preoperative • 5. Intraoperative • 6. Postoperative • 7. Treatment • 8. Outcomes • 9. Summary Objectives

15. Seventh Joint National Committee on the Detection, Evaluation and Treatment of High Blood Pressure (JNC VII) [2003] • British Hypertension Society Guidelines [1999] • World Hypertension Society/International Society of Hypertension (WHO/ISH) guidelines • Differ w.r.t inclusion of target organ damage and the limit for initiating treatment Definition of Hypertension?

18. Acute and Chronic Hypertension: Clinical Context Chronic Hypertension Acute Hypertension Syndromes Hypertension Emergencies

19. Classification of Severe Hypertension • Uncomplicated Stage 3 HTN • Hypertensive Crises • Urgencies • Emergencies JNC VI. Arch Intern Med 1997;157:2413-2448

20. Hypertensive Urgencies: Defined by Effects or Setting • Hypertension with •  Progressive target organ damage

21. Hypertensive Emergencies: Defined by Effects Severe HTN with acute end organ damage:  Central nervous system  Myocardial ischemia or heart failure  Renal damage  Active hemorrhage Eclampsia Microangiopathic hemolytic anemia  Aortic dissection

22. Hypertensive Emergencies:

23. Hypertensive Emergencies:

24. Acute Hypertension Hypertensive Urgency Severe HTN WITHOUT acute end-organ damage Requires BP control over severaldays-weeks Hypertensive Emergency Severe HTN (BP >180/120 mm Hg) WITH end-organ damage Requires immediate, aggressive BP control Perioperative Hypertension HTN* occurring prior to, during, or following surgical procedures Requires immediate BP control Acute Hypertension * Poorly defined

25. Hypertension occuring in the pre-operative, intra-operative or post-operative period. • Importance: • Increased risk of cardiovascular events • Increased post-operative morbidity and mortality • Association with end-organ damage Perioperative Hypertension

27. Prevalence of HTN by Age HTN Risk > 115/75 NHANES: 1999-2004. Source: NCHS and NHLBI.

29. Pathophysiology

30. Hyperadrenergic response to surgery Increase SVR, decrease preload Rapid intravascular volume shifts Renin angiotensin activation Adrenergic stimulation (cardiac & neural) Serotonergic overproduction Baroreceptor denervation Altered cardiac reflexes Inadequate anesthesia Cross clamp Physiology Perioperative Hypertension SVR; Humoral vasoconstrictors Mechanical stress Endothelial injury Permeability Coagulation Fibrinoid necrosis Marik P. Chest. 2007;131:1949-1962.

31. Normal LargeArteries(hypertrophic) inPPH Outward Hypertrophic remodeling Remodeling Inward Eutrophic remodeling SmallArteries(eutrophic)in diastolic HTN Courtesy of Schiffrin EL. Courtesy of Schiffrin EL.

32. Pathogenic Role of Mechanical Forces Oscillatory Shear Stress* Occurs sites prone to lesion formation Carotid bulb Prox. Coronaries Distal aorta High Shear  Atheroprotective Low Shear  Atherogenic *Wide PP  Augments Oscillatory Shear Pressure/Stretch Elevated Stretch with Hypertension Pro-Inflammatory / Atherogenic

33. The Endothelium Modulates Vascular Tone O Catecholamines X NO AT-II TxA2 Endogenous vasoconstrictors Endogenous vasodilators O2- Endothelium PGI2 Aldosterone ADH (vasopressin) Courtesy of JJ Ferguson III, MD.

34. Proposed Vascular Pathophysiology of Hypertensive Urgency CAMs Catecholamines AT-II NO Endogenous vasoconstrictors TxA2 Endogenous vasodilators ( - ) ( + ) ET1 PGI2 Aldosterone ADH (vasopressin) O2- Acute ↑ BP triggers ↑cellular adhesion molecular expression Vaughan CJ, Delanty N. Lancet. 2000;356:411-7.Courtesy of JJ Ferguson III, MD.

35. Proposed Vascular Pathophysiology of Hypertensive Emergency TxA2, PAI-1, TF • Overwhelmed control of vascular tone leads to coagulation cascade activation • Loss of endothelial activity coupled with coagulation and platelets promotes DIC Vaughan CJ, Delanty N. Lancet. 2000;356:411-7. Courtesy of JJ Ferguson III, MD.

36. Major physiologic derangements Mechanical stress on the vessel wall Release of Local humoral vasoconstrictors ↑BP Augments HTN Further release of humoral vasoconstrictors Pressure natriuresis Pathophysiology of Acute Hypertensive Syndromes Volume depletion Fibrinoid necrosis of small blood vessels Endothelial damage Vasopressin endothelin catecholamines RAAS activation Activation of the clotting cascade Courtesy of JJ Ferguson III, MD.

37. Sympathetic Nervous System Regulation of Blood Pressure CNS Adrenal Gland Adrenergic Tone Catecholamines Baroreceptor Reflexes Veins Arteries Capacitance Resistance Afterload Preload Volume/Pressure Cardiac Output Renin/Angiotensin Heart Kidney Blood Pressure

38. Renin-Angiotensin-Aldosterone Regulation of Blood Pressure Renin Substrate Angiotensin I Angiotensin II Renin Aldosterone Vasoconstriction Kidney Adrenal Cortex Blood Pressure Sodium & Water Reabsorption

39. CVS effects: • Increased BP→ ↑ afterload & myocardial oxygen demand → myocardial oxygen supply and demand imbalance. • Chronic ↑ BP → myocardial hypertrophy → myocardial oxygen supply and demand imbalance • Hypertrophied myocardium → decreased compliance → abnormal diastolic filling Effects of Perioperative Hypertension

40. Effects of Perioperative Hypertension • CNS effects: • Increased risk of stroke • Impaired cerebral autoregulation • Especially important in neurosurgical patients • Effects on renal function • Effective control of BP prevents renal dysfunction • Intraoperative urine output monitoring for assessment of perioperative renal function

42. Patients with well-controlled HTN preoperatively less likely to experience intraoperative BP lability & postop complications • Recent UpToDate Meta-Analysis suggests that in patients with hypertension, elective surgery does not need to be delayed as long as the blood pressure is below 170/110 mmHg. • Patients taking chronic antihypertensive meds should CONTINUE taking meds until time of Sx. Preoperative Period UpToDate June 27, 2013: Perioperative management of hypertension

43. Preoperative Period Comfere T et al. Anesth and Analg 2005; 100: 636-44

45. Hemodynamic Response to Laryngoscopy Kihara et al. AnesthAnalg 2003; 96: 890-5

46. Intraoperative Period Prys-Roberts C et al. BJA 1971; 43: 122-137

49. 17,638 consecutive day surgery patients • Hypertension and intraoperative adverse events • Any event OR 2.2 (1.4-3.6) • Cardiovascular events OR 2.5 (1.5-4.2) • Hypertension 174 (76%) • Arrhythmia 21 (9.2%) • Hypotension 14 (6.1%) • Bradycardia 13 (5.7%) • Tachycardia 7 (3.1%) Intraoperative Period Cheung F et al. BJA 1999; 83: 262-70

50. Acute BP elevations > 20% considered hypertensive emergency • Chronic Htive patients more likely to be labile • Result in increased risk of postop mortality & renal failure, especially during CV procedures • Htive events more commonly during carotids > abdominal aorta > peripheral vascular > intraperitoneal > intrathoracic surgeries. • If known LV dysfunction +/- CAD, increased risk of myocardial ischemia or CHF. Intraoperative Period Perioperative hypertension: Diagnosis and Treatment. Varon 2011 NJCC