TOC |
Cardiology
Renovascular Hypertension -
unilateral or bilateral stenosis
REF: Cleveland Clinic J of
Med Dec. 2005, Vol. 72: 1135
Causes of Renovascular Hypertension:
-
Atherosclerosis of renal arteries
(accounts for nearly 90% of cases)
-
Fibromuscular dysplasia of renal
artery (accounts for nearly 10% of cases)
- intimal 1-2%, periarteirla 1-2%, medial 96%
-
Renal artery aneurysm
-
Systemic vasculitis
-
Arteriovenous fistula
-
Subcapsular intrarenal hematoma (Page kidney)
-
Renin-secreting renal tumors
-
Extrinsic compression of either kidney or renal artery due
to tumors or metastases
-
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:
-
Plasma renin activity
Limitations: - affected by BP meds & diet and relatively low sensitivity
57% and specificity 66%.
-
Renal vein renin ratio
Limitations: - invasive, lacks sensitivity & specificity, influenced by
drugs and volume status.
-
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.
-
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
-
Magnetic resonance angiography (MRA)
- *
Advantages: low nephrotoxic potential
Limitations: - high cost; signal corruption due to metallic stents
-
CT angiography
Advantages: improved visiualization
of branch vessels
Limitations: - limited use in renal insufficiency due to high contrast
requirement of >150 mL
-
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:
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
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
Aortic
Coarctation
(weak or absent femoral pulses ) - A constriction (discrete or of varying
lengths) of the aorta usually located just distal to the left subclavian
artery at the junction of the ligamentum
arteriosum.
[Ref: Dambro: Griffith's 5-Minute Clinical Consult, 1999]
-
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