Question

Case: Rollie Hendrix is a 35-year-old husband and father of three children. Over the past six months he has experienced headaches and palpitations of increasing frequency and severity. In addition, he has periods of intense anxiety and panic attacks. His wife Arlene has noticed that Rollie’s face is often pale and that he sweats more. Upon examination by his physician, Rollie was found to be severely hypertensive and in atrial fibrillation. Rollie’s physician suspected that he might have a Pheochromocytoma and ordered a battery of tests, which confirmed his diagnosis.

What is a Pheochromocytoma? Explain the cardiovascular effects of epinephrine and norepinephrine when they bind to adrenergic receptor types. Why are patients with a pheochromocytoma often hyperglycemic, sweat excessively, and be constipated? How should Rollie be treated (Do not put the obvious answer to remove tumor)?

Answer 1

Pheochromocytoma are Catecholamine( Epinephrine ,nor epinephrine ) screting neural crest cells tumour arising from
1) Adrenal glands ----> Adrenal Pheochromocytoma
2) Sympathetic / Parasympathetic ganglia ---->Extraadrenal Pheochromocytoma / Paraganglioma

*Adrenal Pheochromocytoma (75%) secrete ( Epinephrine >>Norepinephrine )rarely Dopamine

*Extraadrenal Pheochromocytoma / Paraganglioma ---->Exclusively Norepinephrine .

Effects of Epinephrine and Nor epinephrine on Heart.

Heart have beta 1 receptor .Activation of beta 1 adrenergic receptor result in
a) Positive Chronotropic effect --->Increase rate of contraction
b) Positive Inotropic effect --->Increased force of contraction .
C) Positive Dromotropic effect --->Increased conduction through heart .

Effects of Epinephrine on other sites
1.Hyperglycaemia is caused by promotion of Glycogenolysis( breakdown of glycogen into glucose )and Gluconeogenesis ( formation of glucose )on Beta 2 stimulation in Liver .
Also alpha 2 stimulation contributes to hyperglycemia by reducing the release of Insulin from beta cells of pancreas .
Minor beta 2 mediated increase in Glucagon secretion also is responsible for elevation in blood glucose levels .

2.Sweating is stimulated by Sympathetic cholinergic receptors ( M3 receptors ) present on sweat glands .Binding of epinephrine on M3 receptor cause its activation and excessive sweating occur.

3.Constipation --> Epinephrine cause relaxation of smooth muscles of gastrointestinal system decreasing motility ,secretions through Beta 2 receptor present over there and also constrict the external anal sphnicter via alpha 1 receptor present over there resulting In Constipation.

Treatment
1. Admit 7-10 days prior to surgery

2. Volume repletion is done with High salt diet

3. 7 Days prior to surgery ---> Non selective irreversible Long acting alpha blocker is used ( Phenoxybenzamine ) 10 mg BD .Also Phentolamine and Prazosin can be used .They cause Vasodilation and widen the blood vessels improving the blood flow and decreasing the blood pressure .

4. 3 days prior to surgery ---> Beta blocker is used ( Propranolol 60 mg 6 hrly then once daily ) .It will decrease the heart rate and also widen the blood vessels .

5.Also drugs like Nicardipine ,Metyrosine tried

6.If pateint develops Hypertensive crisis then Sodium Nitroprusside is the drug of Choice .Next ljne is Nicardipine and Phentolamine .

7 .Clonidine Suppresion test done to decrease the catecholamine release .

Finally surgery
If Sporadic case---->Laproscopic Retroperitoneal Adrenalectomy ( Unilateral )
If genetic cause --->Bilateral Partial Adrenalectomy