Table of contents
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Renovascular HTN
- Typically when > 70% luminal narrowing of renal arteries
- Suggest Renovascular HTN:
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Suggesting renovascular HTN if: (≥ 2 of:)
1. Sudden onset or worsening HTN at age >55 or < 30yo
2. Abdominal bruit
3. Resistant HTN (≥3 drugs)
4. Increase in creatinine ≥ 30% with initiation of ACEi
5. Atherosclerotic vascular dz in pts who smoke or have dyslipidemia
6. Pulmonary edema with hypertensive surges
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- Exam:
- Hear epigastric bruits (both atherosclerotic and FMD mechanisms)
- Two types:
- Atherosclerosis
- Vascular risk factors (i.e. smoking, dyslipidemia)
- Proximal renal arteries
- Fibromuscular Dysplasia
- Younger patients (women)
- Distal renal arteries
- Atherosclerosis
- Mechanism:
- Unilateral --> Elevates BP through renin-mediate mechanism
- Bilateral --> Sodium excess elevate BP
- Diagnosis:
- Captopril-enhanced radioisotope renal scan
- Do not use in CKD (GFR < 60)
- MRI Angiography (gadolinium)
- CT angiography (for those with normal renal function) (Grade B). (Grade D).
- Renal Doppler
- Recommended if GFR < 30 (cannot use iodinated or gadolinium contrast)
- Captopril-enhanced radioisotope renal scan
- Treatment
- Fibromuscular Dysplasia
- Percutaneous renal angioplasty --> treatment of choice.
- Atherosclerotic Disease
- Controversial!!!
- ASTRAL Trial and STAR Trial do not support angioplasty over medical therapy.
- Recommendations:
- Aggressive risk factor modification (BP control, dyslipidemia therapy, smoking cessation).
- Percutaneous stenting ONLY for those with refractory HTN despite extensive treatment, or progressive loss of renal function.
- Bilateral Renal Artery Disease --> at risk of worsening renal function when treated with RAAS drugs (ACEi or ARBs). Especially in those with aggressive diuretic use. Be careful if serum creatine rises > 25% of baseline.
- Fibromuscular Dysplasia
Hyperaldosteronism
Suspect when:
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Screening for hyperaldosteronism should be considered:
- HTN + spontaneous ↓K (K+ < 3.5 mmol/L);
- HTN + marked diuretic- induced ↓K (K+ < 3.0 mmol/L);
- Resistant HTN (≥ 3 drugs)
- HTN + incidental adrenal adenoma
Diagnosis:
- Step #1 Perform a Screening Test:
- Plasma aldosterone & plasma renin activity OR renin mass/concentration
- Must collect in morning after patient ambulatory >2h (incl sitting/standing/walking)
- Must be seated for 5-15min prior to blood draw
- Hypokalemia should be corrected & sodium intake liberalized
- Remove agents that affect testing (aldosterone antagonists, potassium sparing/wasting diuretics) --> Must withdraw 4-6w prior
- Medications not affecting test: slow-release verapamil, hydralazine, prazosin, doxazosin, terazosin)
- If results nondiagnostic, remove: beta blockers, alpha-2-agonists, ARBs, ACEi, renin agonists, dihydropyridine CCB.
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A. To estimate: B. From: Multiply (B) by: Plasma renin concentration (ng/L) Plasma renin activity (ng/mL/hr) 0.192 Plasma renin activity (ng/L/sec) Plasma renin activity (ng/mL/hr) 0.278 Plasma aldosterone concentration (pmol/L) Plasma aldosterone concentration (ng/dL) 28
- Positive Screening Test: plasma aldo-to-renin activity ratio > 750 pmol/L/ng/ml/hr (or 144 pmol/L/ng/L when renin is measured as renin mass or concentration)
- Step #2: If screening test positive, autonomous aldo secretion present: Do Confirmatory test
- If adrenal mass present + eligible for surgery --> Adrenal venous sampling (assess for lateralization of secretion)
- saline loading tests (perform either):
- Administer 2L of normal saline IV over 4h with the patient in a recumbent position. Primary hyperaldosteronism is defined as a post-infusion plasma aldosterone >280 pmol/L. If <140 pmol/L, primary hyperaldosteronism is unlikely. Values in between are considered indeterminate;
- Administer PO sodium, 200 mmol/day x3 days, with primary hyperaldosteronism defined as a 24-hr urinary aldosterone >33 nmol/d (measured from the morning of Day 3 to the morning of Day 4). If <28 nmol/day, primary hyperaldosteronism is unlikely.
- a plasma aldosterone to PRA ratio greater than 1400 pmol/L/ng/ml/hr (or 270 pmol/L/ng/L), with a plasma aldosterone greater than 440 pmol/L.
- captopril suppression test: Administer 25-50mg captopril orally after the patient has been sitting or standing for 1 hour. While seated, renin and plasma aldosterone levels should be measured at time zero and 1-2 hours after ingestion. Primary hyperaldosteronism is unlikely if plasma aldosterone is suppressed by >30% following captopril ingestion. In primary hyperaldosteronism, plasma aldosterone remains elevated, while renin remains suppressed.
- Step #3: Primary Hyperaldosteronism Subtype Classification
- Adrenal CT or MRI to localize lesion
- If lesion found & fit for surgery--> do adrenal venous sampling to see if it is source of hypersecretion
- If imaging normal & fit for surgery
- Adrenal Venous Sampling --> bilateral or unilateral production? for possible adrenalectomy
- If family history of hyperaldosteronism or young stroke ≤40yo OR onset of HTN ≤ 20y and negative imaging --> test for Glucocorticoid Remediable Aldosteronism
Management
- Surgery? - find out if candidate (above testing) --> possible unilateral laparoscopic adrenalectomy
- Medications:
- Mineralocorticoid Receptor Antagonists (i.e. aldosterone)
Pheochromocytoma
- Increase BP through norepinephrine and epinephrine.
- Diagnosis requires a very high degree of suspicion
- Suspect when:
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Suspect Pheochromocytoma when:
- Paroxysmal and/or severe (BP ≥ 180/110) sustained HTN refractory to anti-HTN therapy
- HTN + symptoms suggesting catecholamine excess (headaches, palpitations, sweating, panic attacks, pallor)
- HTN triggered by B-blockers, MAO Inhibitors, Micturition, abdominal pressure
- HTN + incidentally discovered adrenal mass + MEN2A/2B or von Recklinghausen neurofibromatosis or von Hippel-Lindau disease
- Positive biochemical screening tests --> Localize with MRI (preferred), CT if MRI unavailable, or I-131 scintigraphy.
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- Investigations:
- Screening:
- 24-hr urine total metanephrines and catecholamines (sn 90-95%)
OR- 24-hr urine fractionated metanephrines (sn 100%) + 24hr urine creatinine (to confirm accurate collection)
- Plasma metanephrine measurement and free normetanephrines, where available may be considered (sn 99%)
- Urinary VMA measurements should not be used for screening
- 24-hr urine total metanephrines and catecholamines (sn 90-95%)
- If borderline result, or possible false positive result
- Repeat testing and/or clonidine suppression test.
- Do biochemical testing BEFORE imaging (to avoid incidentalomas)
- Imaging:
- MRI (preferred)
- CT (if MRI unavailable)
- I-131 metaiodobenzylguanidine scintigraphy (aka MIBG)
- Screening:
- Treatment:
- Surgical removal!
- Peri-operative management:
- Alpha-blockers started 10-14d pre-op. (can include phenoxybenzamine (long-acting non-selective irreversible alpha-blocker), prazosin, doxazosin
- Add Dihydropyridine CCB
- Add other anti-HTN agents
- Avoid diuretics if possible
- Encourage volume + salt intake pre-op (volume contraction is common)
- Post-Op
- Hold anti-HTN drugs
- May need aggressive IV fluids
- Long-Term
- Follow urinary or plasma metanephrines (screen for recurrence)
- Peri-operative management:
- Surgical removal!
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