Systemic Hypertension

Transcription

1 BCS Theme Session Cardiovascular Block Pathology of Hypertension Department of Pathology University of Sydney Systemic Hypertension Definition of Systemic hypertension: consistent blood pressure elevation at rest >140 systolic and/or >90 diastolic mm Hg Types of Systemic hypertension: Benign - stable for years Malignant - >200/120 mm Hg year course 1

2 Cardiac output is the volume of blood being pumped by the heart in a minute. It is equal to the heart rate multiplied by the stroke volume Cardiac Output Blood Pressure Regulation Aldosterone Blood volume fluid retention Na + reabsorption Heart Rate Stroke volume contractility end-diastolic volume Chamber size Total Peripheral (arteriolar) Resistance Systemic Local Vasoconstrictors Vasodilators Pressure ph Hypoxia humoral neuronal Causes of Systemic Hypertension Idiopathic in ~95% of patients ( essential HT) Secondary to known disease in ~5% Sometimes remediable in this category 2

3 Secondary Causes of Hypertension Kidney: Chronic renal / renal-vascular disease press/flow afferent arteriole JG cells Renin Plasma angiotensinogen Angiotensin I (ACE) Angiotensin II: constriction of VSMC PR BP aldosterone secretion reabsorption of Na + blood volume CO BP Endocrine: Adrenal medullary tumour eg phaeochromocytoma Cardiovascular: Coarctation of the aorta Renal causes of Hypertension (1) a derangement in the renal handling of sodium and fluids leading to volume expansion, or (2) an alteration in renal secretion of vasoactive materials resulting in a systemic or local change in arteriolar tone. Reno-vascular hypertension (eg renal artery stenosis, renal artery fibromuscular dysplasia): Decreased perfusion of renal tissue (nearly always because of atherosclerosis) Activates the renin-angiotensin system Circulating angiotensin II elevates arterial pressure: By directly causing vasoconstriction, by stimulating aldosterone secretion with resulting Na + retention, and/or By stimulating the adrenergic nervous system. Renal Parenchymal Disease (eg acute and chronic glomerulonephritis, polycystic disease, renal vasculitis): Decreased perfusion of renal tissue due to inflammatory and fibrotic changes involving multiple small intrarenal vessels, Activates the renin-angiotensin system Renal tumours: Rare results from the excess secretion of renin by juxtaglomerular cell tumors or nephroblastomas Initial presentation is similar to that of hyperaldosteronism, with hypertension, and overproduction of aldosterone. 3

4 J9 Kidney Diabetes Renal artery atheroma x a Renal artery fibromuscular dysplasia H&E x25 4

5 Normal kidney cut surface Cortex Medulla (including renal pyramid) Pelvo-calyceal system (embedded in fat) Normal kidney 5

6 Kidneys: Chronic Glomerulo- nephritis Cortical thinning Indistinct corticomedullary junction Enlarged fat filled hilum Adrenal cortical adenoma Adrenal Adenoma Adrenal cortical adenomas are usually non-functional and an incidental finding. However, they can cause: Hyperaldosteronism (hypertension, hypokalemia) Cushing Syndrome (hypercortisolism HT, wt gain, centripetal fat etc) 6

7 Adrenal Phaeochromocytoma Adrenalin secreting tumour 10% may be malignant 70% cause chronic hypertension 50% have paroxysmal episodes of HT, palpitations etc 10% are extra-adrenal eg carotid body Heart in Benign HT Concentric left ventricular hypertrophy Heart weight exceeds 250 gm in women and g in men (these are approx normal ranges) (Build of patient is important in determining the upper level of normal) 7

8 Normal Heart (posterior view) Left Atrium Mitral valve Chordae tendineae Papillary muscles Left Ventricle Right Atrium Tricuspid valve Right Ventricle Post. IV groove Left ventricular concentric hypertrophy in hypertension 8

9 Cardiac Myocytes Normal Hypertrophy I Myocardial Hypertrophy: abnormal nuclei H&E x250 9

10 Myocardial perfusion myocytes blood vessel blood vessel NORMAL Necrotic myocyte -> Fibrosis HYPERTROPHIED I37-1 Heart hypertrophy interstitial fibrosis H&E x20 10

11 Effects of hypertension on the vascular system The Arteries Loss of elastin and smooth muscle in the media, with replacement by fibrous tissue = hypertensive arteriosclerosis (an exaggeration of age changes) High risk factor for atherosclerosis Atheromatous coronary artery 11

12 Hypertensive vascular damage to kidney Kidney is supplied by end arteries Glomeruli supplied first Medulla is supplied (in line) after glomeruli Normal kidney cut surface 12

13 Normal kidney Kidney in Benign Hypertension Loss of glomeruli and related nephrons Hyperplasia of tubules of surviving nephrons Bilateral finely granular contracted kidneys result Renal function is seldom compromised 13

14 Kidney: hypertensive nephrosclerosis (interior) Kidney hypertensive nephrosclerosis (exterior) 14

15 Dr Hambly will now appear! Effects of HT on Vascular System Arterioles: Replacement of smooth muscle with homogeneous eosinophilic hyaline in walls of afferent arterioles.the lumen of these vessels is narrowed. Elongation of these vessels leading to tortuosity. 15

16 Nephron within the Kidney J17 Hypertensive vascular damage to kidney 16

17 J17 Kidney benign hypertension: thick walled artery H&E x50 J17 Kidney benign hypertension: hyaline afferent arteriole x100 17

18 J17 Kidney benign hypertension: tortuous benign afferent arteriole J17 Kidney benign hypertension: obsolete glomerulus and tubular atrophy H&E x50 18

19 J17 Kidney benign hypertension: subcapsular scar H&E x20 Brain in Benign Hypertension Increased risk of cerebral infarction (atherosclerosis), a common form of stroke Increased risk of intracerebral haemorrhage (degeneration of penetrating arteries) Increased risk of rupture of berry aneurysms in Circle of Willis with subarachnoid haemorrhage 19

20 Internal capsule White matter deep in the brain connecting cerebral cortex with brainstem and spinal cord Horizontal section Coronal section Cerebral striate vessel in hypertension: thick walled muscle lost 20

21 Micro cerebral striate artery microaneurysm in hypertension Brain: Intracerebral Haemorrhage 59 yo woman with long Hx HT Large hemorrhage into R basal ganglia & ventricles Flattening of gyri and midline shift 21

22 Brain: Aneurysm (unruptured) Macro - unruptured berry aneurysm of circle of willis 22

23 Micro - unruptured berry aneurysm LP Brain: Ruptured Saccular (berry) Aneurysm 23

24 Types of hypertension Benign stable Malignant unstable and accelerated with diastolic pressures > 120 mmhg 1455 Kidney - malignant hypertension: fibrinoid necrosis of arterioles, glomeruli 24

25 Retina - normal Retina - hypertensive AV nipping 25

26 Retina Malignant hypertension Papilloedema of optic cup Cotton wool exudates Flame hemorrhages Deaths due to undiagnosed or inadequately controlled hypertension Congestive cardiac failure (often biventricular) 60% Strokes 30% Aortic dissection (comparatively infrequent) However, renal failure in benign hypertension is uncommon 26

27 Macro aortic dissection Bottles and Slides (for lab) J17 Hypertensive vascular damage to kidney KIDNEYS - CHRONIC GLOMERULONEPHRITIS ADRENAL - CORTICAL ADENOMA Adrenal phaeochromocytoma HEART - HYPERTENSION Atheromatous coronary artery Atheromatous coronary artery Normal kidney Kidney hypertensive nephrosclerosis Brain Intracerebral Haemorrhage BRAIN - ANEURYSM (UNRUPTURED) BRAIN - SACCULAR (BERRY) ANEURYSM 27