Hypertension is a condition in which the blood pressure in the arteries is chronically elevated.
The pressure is determinated by the cardiac output and Total peripheral resistance(TPR), according to the mathematical formula ΔP= R*Q
the first factor R interests the sum of the resistance of all peripheral vasculature in the systemic circulation, the second one (Q) is the flow through the vasculature, pushed by the heart contraction.
We individuate two measurements, systolic and diastolic, which depend on whether the heart muscle is contracting (systole) or relaxed between beats (diastole).
Normal values are usually lower than 80, for the diastolic, and lower than 120 for the systolic.
Illustration 1: Guide lines ESH/ESC (European Society of Hypertension and European Society of Cardiology.
Unfortunately different causes can lead to an increase of one or both of this value.
Major causes are:
* Lifestyle factors ( a sedentary life, a major salt intake, assumption of fat products, low physical exercise and alcohol intake )
* Caffeine consumption
This regards especially the Essential hypertension, defined also “idiopatic”, because has no identifiable cause. It is the most common type of hypertension, affecting 95% of hypertensive patients. It tends to be familial and it is the consequence of an interaction between environmental and genetic factors.
Contrariwise the secondary hypertension has many different causes, linked to other disease. For example:
* Renal disorders
* Endocrine disorders
* Sleep disturbances
* Potassium deficiency
* Medication side effects ( Non-steroidal anti-inflammatory drugs, estrogen, ..)
In particular, we are interested in a rare endocrine disorder: pheochromocytoma.
Its incidence is mostly seen in Minnesota (USA): 1-2/100.000. it occurs in young or middle age adults, except for the hereditary cases.
Pheochromocytoma is a neuroendrocine tumor of the medulla part of the adrenal glands, that affects the chromaffin cells or extra-adrenal chromaffin tissues derived from neuroectoderm migrated in other tissues, for example ganglion of autonomic nervous system or carotid glomus (less common)
This tissue secretes an excessive amount of catecholamines: noradrenaline (norepinephrine), and adrenaline (epinephrine). This can lead to hypertension because of the effects of both amines.
They are associated to stress, pain and fight or flight response.
They act on two receptors:
• α(α1, α2): vasoconstriction of coronary artery, veins and decrease motility of smooth muscle in GI tract
• β(β1, β2, β3): increase cardiac output, impulse conduction, contraction and the ejection fraction ( they have positive chronotropic , dromotropic, inotropic effect)
Major effects are:
• contraction of the smooth muscle
• increase in pressure and heart rate
• stimulation of lipolysis
• a general reaction of the sympathetic nervous system
The most common presentations of pheochromocytoma are headache, excessive sweating and increased heart rate.
The signs and symptoms include:
•Elevated blood pressure
•Anxiety often resembling that of a panic attack
•Localized amyloid deposits found microscopically
•Elevated blood glucose level
Some people, however, never develop symptoms of a pheochromocytoma: up to 10% of cases are discovered accidentally conditions associated to pheochromocytoma
It can be a component of genetic syndromes, the most common is multiple endocrine neoplasia (MEN), transmitted from parent to child in an autosomal dominant manner.
Pheochromocytoma is due to a feature of genetic disorders, including Von Hippel-Lindau syndrome and neurofibromatosis. Both are associated with the development of numerous benign and malignant tumors. Finally there are cases of sporadic pheochromocytoma (not linked to familiar disorders). Generally these patients have a bilateral disease (pheochromocytoma in both adrenal glands).
The diagnosis of pheochromocytoma is based on:
• familiar history
• valuation of the classic triad of symptoms -- headache, sweating, and heart palpitations
• the measurement of blood pressure
• the evaluation of the concentration of catecholamines and metanephrines in a 24 hour urine collection (or blood)
• MRI (Magnetic Resonance Imaging) or CT scan (Computerized Tomography) of the adrenal glands (if it shows a mass in the gland or outside it).
Surgery is necessary if there is assurance of the tumor. Controlling blood pressure before and during surgery is the trickiest part of care: in fact there is a chance of developing an acute hypertensive crisis after anesthesia.
In the rare instances of malignant pheochromocytoma chemotherapy or radiation therapy may be required after surgery.