TOC | Cardiology   

Renovascular Hypertension  - unilateral or bilateral stenosis 

REF:  Cleveland Clinic J of Med  Dec. 2005, Vol. 72: 1135 

Causes of Renovascular Hypertension:

1. Atherosclerosis of renal arteries (accounts for nearly 90% of cases)

2. Fibromuscular dysplasia of renal artery (accounts for nearly 10% of cases)
    - intimal 1-2%, periarteirla 1-2%, medial 96%

3. Renal artery aneurysm

4. Systemic vasculitis

5. Arteriovenous fistula

6. Subcapsular intrarenal hematoma (Page kidney)

7. Renin-secreting renal tumors

8. Extrinsic compression of either kidney or renal artery due to tumors or metastases

9. Aortic coarctation 

Clinical Features of Renovascular Hypertension:

Suggestive features: 

• Unexplained renal insufficiency

• Abdominal systolic-diastolic bruits

• Unprovoked hypokalemia

• Onset of hypertension at age <30 yo for fibromuscular dysplasis or >50 yo for atherosclerotic renal artery stenosis

• History of flank traumaGeneralized atherosclerosis

• Smoking

• Difference in kidney size of >1 cm

• Absence of family history of hypertension 

Tests for evaluating the renal arteries: 

1. Plasma renin activity
   Limitations: - affected by BP meds & diet and relatively low sensitivity 57% and specificity 66%.

2. Renal vein renin ratio 
   Limitations: - invasive, lacks sensitivity & specificity, influenced by drugs and volume status.

3. Captopril renography 
   Limitations: lack of accuray with serum creat >2 mg/dL and bilateral disease; patients should be off diuretics and ACE inhibitors 1-2 weeks before testing.

4. Duplex renal artery sonography - popular screening test 
   Advantages: useful in serial measuements; additional info regarding kidney size or hydronephrosis.
   Limitations: - highly operator-dependent; limited by obesity, bowel gas interference

5. Magnetic resonance angiography (MRA) - * 
   Advantages: low nephrotoxic potential
   Limitations: - high cost; signal corruption due to metallic stents 

6. CT angiography 
   Advantages:  improved visiualization of branch vessels 
   Limitations: - limited use in renal insufficiency due to high contrast requirement of >150 mL 

7. Renal arteriography with contrast remaisn the gold standard to determine the degree & location of renal aratery stenosis.
   Limitations: can cause deterioration of renal function due to contrast nephropathy, atheroembolic disease, or both. 

Indications for Revascularization if stenosis is present:

• Accelerated hypertension

• Resistant hypertension

• Hypertensive urgency

• Hypertensive emergency:
  Myocardial ischemia
  Aortic dissection
  Hypertensive retinopathy
  CNS abnormalities
  Acute renal insufficiency

• Worsening renal function during antihypertensive Rx, particularly with ACE-inhibitors.

• "Flash" pulmonary edema 

Invasive treatment for Renovascular Hypertension: 

• Percutaneous Transluminal Renal Angioplasty (PTRA) with stenting 

Medical Therapy for Renovascular Hypertension
- ACE inhibitors (as Lisinopril type med) or ARB (as Cozaar) are widely accepted as being superior to other antihypertensive drugs in controlling renovascular hypertension, but it has the potential to precipitate acute renal failure.  Close follow-up of kidney function and potassium levels should be done.
- Treatment for hyperlipidemia and diabetes if present, off smoking, exercise, etc. 

HYPERTENSION- Secondary                     See also BP Medications  |  Hypertensive Crisis

Secondary hypertension is hypertension of known etiology. It accounts for fewer than 5% of all cases of hypertension.

Clinical clues for secondary hypertension:

• Onset of hypertnsion at age <20 or >50
• Stage III hypertension
• Poor response to drug therapy (refractory)
• Increase in BP in previously well controlled hypertensive
• Significant target organ damage (retinopathy, LV hypertrophy, proteinuria)
• Lack of a family history of hypertension

Causes of Secondary Hypertension:

Renal

• Chronic renal parenchymal disease  (edema, nocturia, increased creatinine)
  - acute glomerulonephritis (GN)
  - primary glomerular disease: focal glomerulosclerosis, membranoproliferative GN, mesangioprolif. GN,
     membranous nephropathy
  - chronic interstitial nephritis, diabetic nephropathy, hypertensive nephrosclerosis, chronic pylonephritis,
    obstructive uropathy, polycystic kidney disease.
• Renovascular disease  (abd. vascular bruits)   -  see  Renovascular Hypertension (Cleveland Clinic J of Med Dec. 2005: 72: 1135)
  Conclusions: Computed tomography angiography and gadolinium-enhanced three-dimensional magnetic resonance angiography seem to be preferred in patients referred for evaluation of renovascular hypertension. However, because few studies of these tests have been published, further research is recommended.  Ann Intern Med. Sep. 18, 2001;135:401-411  (Full Text)
• Acute renal failure
• Polycystic kidney disease  (abdominal mass)

Endocrine

• Primary hyperaldosteronism  (hypokalemia)
• Glucocorticoid remedial aldosteronism
• Congenital adrenal hyperplasia
• Pheochromocytoma  (palpitations, anxiety, pallor, labile BP, hyperhydrosis)
• Cushing's syndrome  (purple striae, truncal obesity, muscle weakness)
• Thyroid disease
• Primary hyperparathyroidism  (hypercalcemia, constipation, muscle aches)
• Acromegaly
• Carcinoid

Miscellaneous

• Pregnancy
• Medications oral contraceptives, NSAID, sympathomimetics
• Alcohol
• Acute stress, burns, pancreatitis
• Coarctation of the aorta  (diminished peripheral pulses)
• Head injury
• Spinal cord injury
• Obstructive sleep apnea  (daytime somnolence, snoring, obesity)
• Vasculitis

• SX:   Hypertension, Pulse disparity,  Delayed, weak, or absent pulse, Headaches, Exertional leg fatigue and pain, Prominent neck pulsations, Epistaxis, Prominent left ventricular impulse, Murmur (aortic stenosis or insufficiency, entricular septal defect, rarely mitral valve), S4 systolic ejection click, Bruit (coarctation, collaterals, patent ductus arteriosus), Cyanosis, rarely. Extensive collaterals develop from branches of the subclavian, internal mammary, superior intercostal, and axillary arteries .

• TESTS:
  • Blood pressures - all 4 extremities; Doppler examination of pulses reveals disparity, LVH on ECG 
  • Chest x-ray may show rib notching, "3" sign, rarely cardiomegaly
  • Echocardiography for coarctation and coexisting cardiac anomalies
  • Transesophageal echocardiography
  • Magnetic resonance imaging (MRI)
  • Cardiac catheterization and angiography: post-stenotic dilation

Endocrine Causes:

• Cushing's Syndrome (Truncal obesity, thin skin, muscle weakness)
  Dx: elevated 24 hours urine free cortisol level; or unsuppressed plasma cortisol after dexamethasone 1 mg suppression test; or Dexamethasone 0.5- 2  mg q 6 hours suppression test for 2 days.
  
• Primary Aldosteronism  (Hypokalemia with hypertension)
  DX: low serum K+, increased urine K+, elevated plasma aldosterone & low plasma renin level (high plasma aldosterone/renin ratio>25-30) ; adrenal CT or MRI scan; bilateral adrenal vein catherization with analysis of venous aldosterone & cortisol levels.
  Screening tests include measurement of 8 a.m. plasma aldosterone and renin activity (aldosterone:renin ratios greater than 25:1 suggest inappropriate aldosterone release) in patients who have not received ACE inhibitor therapy in the month before study.
  Confirmatory tests include measurement of 24-hour urinary aldosterone excretion in patients on a high-salt diet (values greater than 14 mg in 24 hours are abnormal).
  Definitive diagnosis is by abdominal computed tomography or MRI. Adrenal adenomas constitute 65% of the cases of primary aldosteronism. If multiple nodules are seen or concerns of an undetected adenoma persist, adrenal vein sampling for aldosterone assay can be attempted. In the absence of adenoma (or, in rare cases, carcinoma), idiopathic aldosteronism and bilateral hyperplasia are diagnoses of exclusion.
  
• Pheochromocytoma (Severe hypertension, palpitation, sweating, headache)
  Dx: 24 hours urine metanephrine, normetanephrine, or 24 hr VMA (vanillylmandelic acid) level; PO Clonidine 0.3 mg suppression test (plasma epinephrine & norepinephrine level 3 hours later), CT or MRI adrenal scan.
  
• Drugs & Hormones: amphetamines, oral contraceptives, estrogens, steroid, or thyroid hormone excess
  
• Carcinoid (rarely) (Cutaneous flushing, diarrhea, and cardiac valvular lesions )
  DX: Increased urinary 5 HIAA
  
• Hyperthyroidism or hypothyroidism
  DX: TSH, T4
  

Renal Causes:

• Renal parenchymal disease: chronic pyelonephritis, congenital renal disease, diabetic nephropathy, glomerulonephritis, interstitial nephropathy, obstructive uropathy, polycystic disease, renin secreting tumors, vasculitis
  DX: BUN, Creat, UA, Renal scan or sonogram.
  
• Renovascular hypertension - renal artery stenosis (RAS) or intrarenal vasculitis; 75% atherosclerosis, 25 % fibromuscular dysplasia (occurs most often in young white females between the ages of 20-40;  Rx is angioplasty), or the uncommon extrinsic compression or thrombosis of the renal artery.  
  The narrow renal artery >70-80% activates the renin angiotensin aldosterone system and leads to increased angiotensin II & aldosterone secretion which increases sodium absorption and thus hypertension.
  The prevalence of renal artery stenosis increases with increasing severity of hypertension, ranging from 1% in patients with a diastolic BP of less than 90 mm Hg to more than 30% in patients with diastolic BP greater than 125 mm Hg.  RAS is more common in Caucasians than in African Americans, & is extremely rare in African American men < 40 years of age.  (Arch IM 1987;147:820 - 829)
  
  SX: Clinical Sx includes resistant hypertension, abd. flank bruits, acute flank pain with hematuria, abrupt onset of hypertension in < 30 yo or > 55 yo.  A precipitous drop in BP, acute deterioration in renal function in response to ACE inhibitor therapy, or both suggest possible RAS and warrant further workup.
  
  DX:
  Screening tests includes the captopril renogram scan, duplex ultrasonography, and magnetic resonance imaging angiography, have a sensitivity that approaches 95% to 100% under optimal conditions. Renal arteriography (digital substraction) is required for definitive diagnosis and presurgical evaluation. Plasma renin activity may be elevated. Renal vein renin sampling may be necessary to identify the culprit kidney in the setting of bilateral RAS.
  The old tests that lack sensitivity & specificity, as IV pyelogram, plain abd. radiographs, & split renal function tests, are no longer considred useful.
• [Conclusions: Computed tomography angiography and gadolinium-enhanced three-dimensional magnetic resonance angiography seem to be preferred in patients referred for evaluation of renovascular hypertension. However, because few studies of these tests have been published, further research is recommended.  Ann Intern Med. Sep. 18, 2001;135:401-411 ]
  
  RX:
  Angioplasty with stent, or revascularization..  If no surgical Rx, diuretics with ACE-Inhibitors (in unilateral Renovascular stenosis only).

Pregnancy-induced Hypertension

Neurological disorders:

• Increased intracranial pressure (brain tumor, encephalitis, resp. acidosis)
• Quadriplegia, sleep apnea, lead poisoing, Guillain-Barre synd., Famial dysautonomia, Acute porphyria

Acute Stress, including surgery

Alcohol & drug use

Increased intravascular volume

Systolic Hypertension

• Increased cardiac output
  • Aortic valvular insufficiency
  • A-V fistula, patent ductus
  • Thyrotoxicosis
  • Hyperkinetic circulation
  • Paget's disease of bone, Beri-Beri
• Rigidity of aorta

REF:

The JNC 7 report. JAMA 2003 May 21; 289:2560-72. [Abstract]
Heart Disease 5th Ed, 1997 - Braunwald
Scientific American Medicine 1999
Postgrad Med Symposium on Hypertension  May 1, 1999;105
The 6th Report of the Joint National Committee 1997  | Quick Note
WHO 1999 Hypertension Treatment Guideline  
Medscape Hypertension Management

2005