Abstract 4148026: Multi-Venous Compression Syndromes Are Characterized by Preload Failure and Dysautonomia

Introduction: Multi-venous compression syndromes pose diagnostic and management dilemmas due to uncertainties in both etiology and clinical course. Clinical thresholds for surgical intervention are unclear, and systemic symptoms beyond the anatomic sites of compression are common, including exertional dyspnea, intermittent tachycardia, and fatigue. We hypothesize that multi-venous compression syndromes may represent a manifestation of autonomic dysfunction with impaired venous return to the right heart (preload failure physiology). Methods: Consecutive patients presenting to the Vascular Medicine clinic, Vascular Surgery clinic, or the vascular ultrasound laboratory at Brigham and Women’s Hospital from November 1, 2021 to May 1, 2024 with evidence of multi-vein compressions were retrospectively included in this cohort. Venous compressions evaluated were thoracic outlet syndrome, popliteal entrapment, left common iliac vein compression, and left renal vein compression. Data were analyzed from autonomic function testing and invasive cardiopulmonary exercise testing (iCPET) performed for clinical indications. Results: A total of 16 patients presented with imaging-confirmed multi-vein compressions. The average (standard deviation) number of compressed sites were 4 (2). Eleven patients (69%) had clinical symptoms of dysautonomia. Five patients (31%) underwent autonomic function testing; all had an abnormal result, most commonly manifesting as reduced orthostatic cerebral blood flow velocity. Seven patients (44%) underwent iCPET; the average right atrial pressure at peak upright exercise was abnormally low at 1 mmHg (1.5 mmHg) with a range of 0-4 mmHg. Four out of 7 patients had accompanying peak oxygen consumption less than 80% of predicted. Seven patients (44%) underwent surgery for at least one compression; the most common procedure was left common iliac vein stenting. Two patients with dysautonomia underwent venous decompression and reported no significant change in overall symptoms. Nine patients with dysautonomia were managed conservatively with medical therapy (salt/water repletion, oral pyridostigmine, beta blocker, midodrine, and/or compression garments). Eight of these patients reported improved functional status after at least 6 months. Conclusions: Patients with multi-vein compressions are enriched for autonomic dysfunction and preload failure. Medical therapy can improve overall functional status without requiring surgical intervention.