Adrenal pheochromocytoma associated with dramatic cyclic hemodynamic fluctuations

Area of Science:

• Cardiovascular Physiology
• Endocrinology
• Nephrology

Background:

• Pheochromocytoma, a tumor of the adrenal medulla, can cause significant and unpredictable blood pressure fluctuations.
• Understanding the detailed hemodynamic changes during these episodes is crucial for patient management.

Observation:

• A 52-year-old woman with right adrenal pheochromocytoma experienced recurrent symptomatic hypotension (systolic blood pressure <50 mmHg) and hypertensive crises (systolic blood pressure >300 mmHg).
• Beat-to-beat non-invasive monitoring captured systolic blood pressure (SBP), diastolic blood pressure (DBP), heart rate (HR), stroke volume (SV), cardiac output (CO), and total peripheral resistance (TPR) over 346 minutes.
• Twenty distinct hemodynamic cycles were observed, averaging 17 minutes each, characterized by substantial variations in all measured parameters.

Findings:

• Total peripheral resistance (TPR) exhibited the most dramatic fluctuations, with a peak-to-trough ratio of nearly 12:1.
• Systolic and diastolic blood pressures showed over 6:1 ratios, cardiac output over 4:1, stroke volume nearly 4:1, and heart rate a 2:1 ratio.
• Changes in TPR consistently preceded alterations in all other hemodynamic variables, suggesting it is the primary driver of the observed cycles.

Implications:

• These findings highlight the critical role of total peripheral resistance in the pathophysiology of pheochromocytoma-induced hemodynamic instability.
• The data underscore the potential for non-invasive monitoring to reveal complex cardiovascular dynamics in endocrine disorders.
• Further research into TPR regulation in pheochromocytoma could lead to improved diagnostic and therapeutic strategies.