Heart rate variability in pheochromocytoma

Pheochromocytoma: an endocrine stress mimicking disorder

A pheochromocytoma is an endocrine tumor that can uniquely mimic numerous stress-associated disorders, with variations in clinical manifestations resulting from different patterns of catecholamine secretion and actions of released catecholamines on physiological systems.

Secondary hypertension: current diagnosis and treatment

Secondary hypertension affects a small but significant number of the hypertensive population and, unlike primary hypertension, is a potentially curable condition. The determinant for workup is dependent on the index of suspicion elicited during patient examination and treatment. Specific testing is available and must be balanced depending on the risk and cost of the workup and treatment with the benefits obtained if the secondary cause is eliminated. This article reviews common manifestations, workup, and the current treatments of the common causes of secondary hypertension.

Characteristics of Blood Pressure in Pheochromocytoma

Pheochromocytomas are catecholamine-producing tumors arising from chromaffin cells. One of the most typical symptoms of the catecholamine-excess state is hypertension either in the sustained or paroxysmal form, and its severity does not depend on the level of circulating catecholamines. On the other hand, hypertension in pheochromocytoma is very often characterized by the amelioration or even inversion of the circadian blood pressure rhythm. In some subjects, high circulating levels of catecholamines lead to the enhanced blood pressure variability. One possible explanation for such blood pressure variability is the desensitization of the catecholamine receptors due to high levels of circulating catecholamines.

Changes in heart rate variability before and after surgery in patients with pheochromocytoma

We assessed ambulatory blood pressure and heart rate variability in two female patients with pheochromocytoma. The ambulatory blood pressure and ECG R-R intervals were measured during a 24-h period with a portable recorder before and 3 weeks after surgery. A power-spectral analysis of R-R intervals was performed to obtain the low-frequency (LF) and high-frequency (HF) components. The percentage of differences between adjacent normal R-R intervals >50 ms (pNN50) was also calculated. In both patients, the plasma epinephrine and norepinephrine levels decreased markedly after surgery. The 24-h blood pressures also decreased after surgery. In both patients, the 24-h average LF component, HF component, and pNN50 decreased after surgery, while the 24-h average LF/HF ratio increased after surgery. These results suggest that high circulating catecholamines inhibit central sympathetic neural outflow and augment parasympathetic nerve activity in patients with pheochromocytoma.