18
Surgical Hypertension
Lucy S. Brevetti, Gregory R. Brevetti, and Rocco G. Ciocca
Objectives
1. To understand when to suspect surgical hypertension.
2. To describe the physiologic basis of the various forms of surgical hypertension.
3. To discuss medical and surgical management of the different types of surgical hypertension.
Case
A 36-year-old man comes to your office complaining of severe headaches, palpitations, and sweating. He gives a history of hyperten- sion for the past 2 years. His medications include nifedipine 90 mg PO qd and atenolol 100 mg PO b.i.d. His blood pressure on exam is 220/105 mm Hg.
Introduction
Hypertension is an extremely common condition that contributes sig- nificantly to the morbidity and mortality of patients who are affected.
Hypertension plays a significant role in cardiac disease, cerebrovascu- lar disease, and other end-organ dysfunction. Its treatment can be difficult, because, unlike in the patient described, it generally is asymp- tomatic.
More than 95% of patients with hypertension have essential hyper- tension, that is, hypertension without a specifically identifiable cause.
Essential hypertension is poorly understood. While it may occur in anybody, it is more common in certain clinical situations. Patients with a family history of hypertension or cardiac or cerebrovascular diseases may be at increased risk. In addition, patients who are obese, who smoke, and who have high sodium intake may be at increased risk. The
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contributing factors, pathophysiology, and treatment options are numerous and complex for essential hypertension and are beyond the scope of this chapter.
Less than 5% of patients have secondary hypertension, which can be treated surgically. Thus, one of the major goals of the history and the physical examination is to direct the clinician to a possible surgical etiology so that laboratory and radiologic evaluations can be tailored appropriately. The differential diagnosis for surgical hypertension can be divided into two main groups: endocrine and vascular (Table 18.1).After a complete history is taken and a physical examination is performed, a good clinician should be able to determine into which category the patient most likely falls and thus should be able to focus the diagnostic studies.
History and Physical Examination
General
The patient’s age is significant because hypertension in a young patient, requiring multiple high-dose antihypertensives, should arouse the suspicion of a possible surgical etiology. The patient presented in our case is considerably younger than average for a hypertensive patient. Hypertension can occur in patients of any age; however, its prevalence increases with age. This patient has hypertension that is symptomatic. This further should increase the suspicion for a surgical etiology.
A cookbook strategy for evaluating hypertensive patients should not be used. An algorithm is useful only when there is a suspicion of a sur- gically correctable etiology to hypertension. (See Algorithm 18.1.)
Endocrine Etiology Conn’s Disease
A history of polyuria and nocturia may suggest primary hyperaldo- steronism (Conn’s Disease).
Cushing’s Disease
Rapid weight gain, early menopause, and oligomenorrheaare sug- gestive of Cushing’s disease, which may be associated with striking physical findings. It is associated with the classically described
“buffalo” hump, moon facies, easy bruising, and striae. Patients with Cushing’s disease also suffer from hirsutism and severe acne. It typi- cally occurs in middle-aged people and may be associated with proximal muscle weakness.
Table 18.1. Frequencies of the most common causes of surgical hypertension.
Endocrine Vascular
Primary hyperaldosteronism (<1%) Renal artery stenosis (<3%) Cushing’s syndrome (<1%) Coarctation of the aorta (<0.1%) Pheochromocytoma (<0.1%)
Polyuria Nocturia ?Hyperaldosteronism Headaches palpitations ?Pheochromocytoma
Hypertensive patient PVD bruitsHistory of congenital heart disease ?Renal artery stenosis Renal artery duplex MRA Angiography Angioplasty Renal artery bypass
CT scan MRI Dexamethasone suppression test
CT scan VMA Urinary catecholamines AdrenalectomySurgical resection Medical antihypertensive therapy
?Coarctation Echocardiogram Angiography Angioplasty Open repair
(+)(–)(–)(+)(+)(–)(–)(+) Algorithm 18.1.Algorithm for the diagnosis and treatment of the hypertensive patient. CT, computed tomography; MRA, magnetic resonance angiography; MRI, magnetic resonance imaging; PVD, peripheral vascular disease; VMA, vanillylmandelic acid.
Pheochromocytoma
Pheochromocytomaclassically is associated with refractory hyperten- sionalong with complaints of headaches, sweating, and palpitations.
A family history of hypertension is a helpful clue. This history usually is related to essential hypertension; however, a precise family history regarding hypertension should be sought. Multiple endocrine neo- plasia syndrome (MEN IIa)is transmitted in an autosomal-dominant fashion. It includes medullary carcinoma of the thyroid, pheochro- mocytoma, and hyperparathyroidism. MEN IIb includes pheochro- mocytoma, medullary carcinoma of the thyroid, and neuromas.
Patients with MEN II may have a palpably large thyroid mass (rep- resenting medullary carcinoma of the thyroid).
Vascular Etiology Renal Artery Stenosis
Renal artery stenosishas been associated with a history of peripheral vascular disease and episodes of pulmonary edema. Hypertension due to renal artery disease may be difficult to control. Bruits may be noted over the renal arteries.
Coarctation of the Aorta
Complex congenital heart diseasemay be associated with coarctation of the aorta. Generally, more complex cardiac disease leads to early, concomitant discovery of coarctation(75% of cases). Only 20% present with hypertension during adulthood. However, coarctation is well described as an isolated lesion. Coarctation of the aorta in young patients may reveal a wide variety of findings depending on associated anomalies. In particular, auscultation of the precordium may reveal murmurs consistent with atrial or ventricular septal defects, aor- topulmonary shunts, or valvular stenoses.
Case Discussion
On physical examination, the patient appears anxious and well nour- ished. His examination is normal except for his level of anxiety and diaphoretic skin. He has no family history of tumors or hypertension.
You obtain a 24-hour urine collection for metanephrines, vanillylman- delic acid, and plasma catecholamines. You increase his atenolol and have him return to your office in 1 week.
Diagnostic Testing
Specific tests are used to rule out a diagnosis suggested by the history and physical findings.
Endocrine Etiology Conn’s Disease
Conn’s diseaseis evaluated by assessing plasma renin activity. These levels remain low despite maneuvers to stimulate secretion, such as
diuretic administration in the presense of Conn’s disease. The most important test, however, is an aldosterone suppression test. In a normal individual, rapid volume expansion should cause aldosterone levels to decrease to below 10 ng/dL. In patients with Conn’s disease, this suppression does not occur. Other tests that are useful in confirm- ing this diagnosis include magnetic resonance imaging (MRI) or computed tomography (CT) scan. In cases in which the diagnosis is established biochemically but the imaging does not reveal the lesion, adrenal vein sampling can help localize the lesion or diagnose bilateral hyperplasia.
Cushing’s Syndrome
Cushing’s syndromeis best evaluated by urinary free cortisol levels.
The high-dose dexamethasone suppression test is a useful adjunct test. A baseline cortisol level is obtained at 8 a.m., dexamethasone 1 mg is taken PO at 11 p.m., and a repeat cortisol level is drawn at 8 a.m. the next day. Cushing’s syndrome is unlikely if suppression of cortisol levels occurs. If urinary cortisol is elevated or suppression does not occur, Cushing’s syndrome is far more likely. The clinician next must evaluate whether plasma adrenocorticotropic hormone (ACTH) is involved in the cortisol elevation. Cushing’s disease (pituitary adenoma) is the most common cause of Cushing’s syndrome and is evaluated by MRI or CT scan. Invasive venous sampling (for ACTH) is useful when imaging studies are equivocal; CT scanning is useful to evaluate the adrenal glands.
Pheochromocytoma
Pheochromocytomais an often discussed but very uncommon tumor.
It can be related to the MEN syndrome approximately 10% of the time and is usually unilateral and benign. If a pheochromocytoma is suspected, the first screening tests are urinary catecholamines, metanephrines, vanillylmandelic acid, and plasma catecholamines.
The clonidine suppression test is used to confirm the suspicion of pheochromocytoma when the urinary or plasma analyses are positive.
A circulating catecholamine level is obtained, and clonidine 0.3 mg PO is administered. Three hours later, an additional level is drawn. If a patient has a pheochromocytoma, the circulating levels fail to suppress after 3 hours. Both CT scanning and MRI are very sensitive for local- ization. Metaiodobenzylguanidine (MIBG) scanning is a functional scan that can reveal the location of a pheochromocytoma not seen on CT or MRI.
Vascular Etiology Renal Artery Stenosis
Duplex scanningusually is the first test used to screen for renal artery stenosis. Sensitivity may be limited by bowel gas or obesity. More specific modalities include magnetic resonance angiography (MRA).
Obtaining renal vein samples for renin levels quantitates the physio- logic significance of the stenosis to the specific kidney. A ratio of 1.5 to 1 is significant and indicates that a stenosis is functionally significant.
The sensitivity of renal vein renin sampling is increased by the administration of captopril prior to venous blood sampling.
Coarctation of the Aorta
Coarctation of the aortausually is diagnosed in early childhood and is associated with more complex cardiac anomalies. Either angiogra- phy or echocardiography can confirm its presence in the neonatal population. In adults presenting with unequal pulses in upper and lower extremities, a CT scan or MRA may be used to evaluate for coarctation. In middle-aged adults and older patients, serious consid- eration should be given to angiography to evaluate a coarctation and to rule out concomitant coronary artery disease.
Case Discussion
The urinary catecholamines and metanephrines are grossly positive.
You proceed with a clonidine suppression test, and it, too, is positive.
You obtain an abdominal CT scan with 2-mm cuts through the adren- als, but no tumor is identified. Next, you get an MIBG scan, and the area just anterior to the aortic bifurcation “lights up.” You discuss this case with your attending, and he congratulates you on your finding of the pheochromocytoma in the organ of Zuckerkandl.
Treatment
Essentially, all cases of hypertension are managed with medications.
The number of classes of medications, types within each class, and dosing regimens are among the most numerous of any type of medication. All types of hypertension are treated with an antihyper- tensive medication (Table 18.2).
Endocrine Etiology Conn’s Disease
Treatment of Conn’s disease depends on whether it is caused by an adrenal adenoma or bilateral adrenal hyperplasia. Once chemically characterized and localized by radiologic studies, these tumors can be treated successfully either by laparoscopic excision (primarily left- sided tumors) or open surgical technique. In addition, chemical adrenalectomyhas been described.
Cushing’s Disease
Cushing’s diseasecan be treated by transsphenoidal resection of the pituitary gland. If there is an exogenous tumor that is secreting ACTH, the condition can be treated by excision of that tumor (i.e., small-cell lung cancer). Treatment of cortisol secreting adrenal tumors is similar to that for Conn’s disease: laparoscopic excision or open sur- gical excision.
Pheochromocytoma
Pheochromocytoma is treated by surgical extirpation, either open or laparoscopic. It usually is in the adrenals, but it can be found
Table 18.2.Antihypertensive drugs. Initial/ maximumFrequencyRelative cost ClassDrugTrade namedose (mg/day)of dosage(dose in mg) DiureticsThiazides ChlorothiazideDiuril500/1500bid1.60 (1000) HydrochlorothiaxideEsidrix50/150bid1.00 (100) Hydro Diuril Oretic Thiuretic HydroflumethiazideSaluron100/150bid2.30 (50) BendroflumethiazideNaturetin10/15qd3.20 (5) TrichlorothiazideNaqua4/8qd2.70 (4) Metahydrin MethylclothiazideEnduron10/15qd1.90 (10) BenzthiazideExna100/150bid2.60 (100) Aquatag PolythiazideRenese2/8qd4.80 (4) CyclothazideAnhydron1/6qd4.20 (4) Phthalimidine derivatives ChlorthalidoneHygroton50/100qd2.90 (50) MetolazoneZaroxolyn2.5/5qd1.90 (5) Loop diuretics BumetanideBumex0.5/1.0qd1.20 (0.5) FurosemideLasix40/160qd1.30 (40) Ethacrynic acidEdecrin50/200qd2.40 (50) Distal tubular diuretics AmilorideMidamor5/10qd2.60 (5) SpironolactoneAldactone50/100tid7.60 (100) TriamtereneDyrenium50/100qd2.10 (100) Combination drugs Amiloride and hydrochlorothiazideModuretic1 tabletqd2.70 (tablet) (5mg amiloride, 50mg HCTZ) Spironolactone andAldactazide1–4 tabletsbid2.23 (2 hydrochlorothiazidetablets) Triamterene andDyazide1–2 tabletsbid1.60 (2 hydrochlorothiazidetablets) Continued
Table 18.2.Continued Initial/ maximumFrequencyRelative cost ClassDrugTrade namedose (mg/day)of dosage(dose in mg) SympatholyticsBeta blockers AtenololTenormin25/100qd4.40 (50) MetoprololLopressor50/300bid4.60 (100) NadololCorgard20/480qd3.05 (40) PindololVisken10/60bid3.50 (10) PropranololInderal40/480bid to qid4.40 (80) TimololBlocadren10/60bid5.90 (20) AcebutalolSectral400/1200qd/bid6.30 (800) Oxyprenolol60/480tid Beta and alpha blocker LabelalolNormodyne200/1200bid5.10 (400) Trandate Alpha blocker PrazosinMinipress2/20bid to tid5.10 (4) Centrally acting ClonidineCatapres0.1/2.4bid3.60 (0.4) GuanabenzWytensin4/32bid5.10 (8) MethyldopaAldomet250/2000qd to tid4.20 (500) ReserpineSerpasil0.1/0.5qd0.50 (0.1) Sandril VasodilatorsHydralazineApresoline50/300bid to qid9.40 (200) MinoxidilLoniten5/100bid5.20 (10) Angiotensin-convertingCaptoprilCapoten25/150bid9.00 (100) enzyme inhibitorsEnalaprilVasotec10/40qd to bid10.20 (20) LisinoprilZestril10/40qd8.09 (20) Prinovil CalciumDiltiazemCardizem120/240tid to qid15.50 (240) channelNifedipineProcardia30/180tid to qid17.70 (60) blockersAdalat VerapamilCalan240/480tid to qid11.10 (320) Isoptin Source:Reprinted from Eagle KA, Haber E, DeSanctis RW, Austen WG. The Practice of Cardiology, 2nd ed. Philadelphia: Lippincott Williams & Wilkins, 1989. With per- mission from Lippincott Williams & Wilkins.
wherever adrenergic tissue is found. General anesthesia can be dan- gerous in these patients. Preoperative treatment with alpha- and beta-blockade is necessary prior to surgery to diminish the state of increased vascular tone. Furthermore, the anesthesiologist must be ready to deal with extremely labile blood pressure using intravenous vasodilators and vasopressors.
Vascular Etiology Renal Artery Stenosis
Renovascular hypertensionmay be treated surgically in patients who are good candidates. A stenosis in the renal artery can be bypassed with either saphenous vein or prosthetic graft. More recently, percu- taneous transluminal balloon angioplasty and stentinghave become safe and less invasive methods of treatment. The long-term results of these techniques are not yet known.
Coarctation of the Aorta
Coarctation in neonatesusually is repaired at the time of surgery for other cardiac anomalies. It can be approached either by a median ster- notomy or left thoracotomy. Various surgical techniques exist, includ- ing resection with end-to-end anastomosis, resection with tube graft interposition, subclavian artery flap repair, and patch angioplasty.
Significant problems have arisen from balloon angioplasty of native aortic coarctation. These include aneurysm formation, increased risk of paraplegia following open repair for “failed” angioplasty, and a high rate of restenosis. However, balloon angioplasty is useful for recur- rent stenosis following open repair(5–10%).
Case Discussion
Your patient with the pheochromocytoma gets medically alpha blocked and then undergoes a successful laparoscopic excision of the tumor. He did well and had a stable postoperative course. He was able to be dis- continued from all of his antihypertensive medications.
Summary
Hypertension is an extremely morbid condition affecting tens of mil- lions of individuals in the United States. The vast majority (95%) of patients have primary, or idiopathic, hypertension. Treatment of these patients is an ongoing process that requires close follow-up and fre- quent adjustments in medications and risk-factor management. A very small percentage of individuals afflicted with hypertension may be amenable to a surgical cure.
This chapter outlined surgical causes of hypertension and their pre- sentation, workup, and treatment. The underlying tenet in the diagno- sis and treatment of surgical hypertension includes a complete history, a complete physical exam, and a high index of suspicion on the part of the clinician. After clinical presentation and suspicion suggest a par- ticular etiology, the clinician has a variety of biochemical and radio-
logic studies to help confirm or rule out the diagnosis. These tests are not indicated in all patients with hypertension. Rather, they should be used selectively, when a reasonable chance of identifying a surgical etiology exists.
Selected Readings
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Joint National Committee on Detection, Evaluation, and Treatment of High Blood Pressure (fifth report). Arch Intern Med 1993;153:154–183.
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