Surgical Hypertension

326 L.S. Brevetti et al.

Table 18.1. Frequencies of the most common causes of surgical hypertension.

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 surgically correctable etiology to hypertension. (See Algorithm 18.1.)

Endocrine Etiology

Conn’s Disease

A history of polyuria and nocturia may suggest primary hyperaldosteronism (Conn’s Disease).

Cushing’s Disease

Rapid weight gain, early menopause, and oligomenorrhea are suggestive 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 typically occurs in middle-aged people and may be associated with proximal muscle weakness.

328 L.S. Brevetti et al.

Pheochromocytoma

Pheochromocytoma classically is associated with refractory hypertension along 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 neoplasia syndrome (MEN IIa) is transmitted in an autosomal-dominant fashion. It includes medullary carcinoma of the thyroid, pheochromocytoma, and hyperparathyroidism. MEN IIb includes pheochromocytoma, medullary carcinoma of the thyroid, and neuromas. Patients with MEN II may have a palpably large thyroid mass (representing medullary carcinoma of the thyroid).

Vascular Etiology

Renal Artery Stenosis

Renal artery stenosis has 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 disease may 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, aortopulmonary shunts, or valvular stenoses.

Case Discussion

On physical examination, the patient appears anxious and well nourished. 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, vanillylmandelic 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 disease is evaluated by assessing plasma renin activity. These levels remain low despite maneuvers to stimulate secretion, such as

18. Surgical Hypertension 329

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 confirming 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 syndrome is 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

Pheochromocytoma is 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 localization. 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 scanning usually 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 physiologic 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.

330 L.S. Brevetti et al.

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 aorta usually is diagnosed in early childhood and is associated with more complex cardiac anomalies. Either angiography 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 consideration 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 adrenals, 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 antihypertensive 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 leftsided tumors) or open surgical technique. In addition, chemical adrenalectomy has been described.

Cushing’s Disease

Cushing’s disease can 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 surgical excision.

Pheochromocytoma

Pheochromocytoma is treated by surgical extirpation, either open or laparoscopic. It usually is in the adrenals, but it can be found

18. Surgical Hypertension 333

wherever adrenergic tissue is found. General anesthesia can be dangerous in these patients. Preoperative treatment with alphaand 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 hypertension may 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, percutaneous transluminal balloon angioplasty and stenting have 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 neonates usually is repaired at the time of surgery for other cardiac anomalies. It can be approached either by a median sternotomy or left thoracotomy. Various surgical techniques exist, including 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 recurrent 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 discontinued from all of his antihypertensive medications.

Summary

Hypertension is an extremely morbid condition affecting tens of millions 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 frequent 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 presentation, workup, and treatment. The underlying tenet in the diagnosis 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 particular etiology, the clinician has a variety of biochemical and radio-

334 L.S. Brevetti et al.

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

Backer CL, Mavroudis C. Congenital heart disease. In: Norton JA, Bollinger RR, Chang AE, et al, eds. Surgery: Basic Science and Clinical Evidence. New York: Springer-Verlag, 2001.

Belli AM. New approaches to the diagnosis and management of renal artery stenosis. J Hum Hypertens 1993;8:593–594.

Hall WD. Diagnostic evaluation of the patient with systemic arterial hypertension. In: Alexander RW, Schlant RC, Fuster V, eds. Hurst’s The Heart, 9th ed. New York: McGraw-Hill, 1998:1651–1672.

Joint National Committee on Detection, Evaluation, and Treatment of High Blood Pressure (fifth report). Arch Intern Med 1993;153:154–183.

Kaplan NM. Clinical Hypertension, 6th edition. Baltimore: Williams & Wilkins, 1994.

Lairmore TC. Multiple endocrine neoplasia. In: Norton JA, Bollinger RR, Chang AE, et al, eds. Surgery: Basic Science and Clinical Evidence. New York: Springer-Verlag, 2001.

Manger WM, Gifford RW Jr. Clinical and Experimental Pheochromocytoma. Cambridge, MA: Blackwell, 1996.

Novick AC. Renal revascularization for atherosclerotic ischemic renal disease. In: Calligaro KD, Dougherty MJ, Dean RH, eds. Modern Management of Renovascular Hypertension and Renal Salvage. Baltimore: Williams & Wilkins, 1996:117–123.

Rossi GP, Chiesura-Corona M, Tregnaghi A, et al. Imaging of aldosterone secreting adenomas: a prospective comparison of computed tomography and magnetic resonance imaging in 27 patients with suspected primary aldosteronism. J Hum Hypertens 1993;7:357–363.

Trainer PJ, Grossman A. The diagnosis and differential diagnosis of Cushing’s syndrome. Clin Endocrinol 1991;34:317–330.

Udelsman R. Adrenal. In: Norton JA, Bollinger RR, Chang AE, et al, eds. Surgery: Basic Science and Clinical Evidence. New York: Springer-Verlag, 2001.

Winterskin BA, Baxter BT. Diseases of the abdominal aorta and its branches. In: Norton JA, Bollinger RR, Chang AE, et al. eds. Surgery: Basic Science and Clinical Evidence. New York: Springer-Verlag, 2001.

Yee ES, Soifer SJ, Turley K, et al. Infant coarctation: a spectrum in clinical presentation and treatment. Ann Thorac Surg 1986;42:488–493.