Iliocaval Venous Obstruction, Cardiac Preload Reserve and Exercise Limitation

Abstract

Cardiac output during exercise increases by as much as fivefold in the untrained man, and by as much as eightfold in the elite athlete. Increasing venous return is a critical but much overlooked component of the physiological response to exercise. Cardiac disorders such as constrictive pericarditis, restrictive cardiomyopathy and pulmonary hypertension are recognised to impair preload and cause exercise limitation; however, the effects of peripheral venous obstruction on cardiac function have not been well described. This manuscript will discuss how obstruction of the iliocaval venous outflow can lead to impairment in exercise tolerance, how such obstructions may be diagnosed, the potential implications of chronic obstructions on sympathetic nervous system activation, and relevance of venous compression syndromes in heart failure with preserved ejection fraction.

Keywords: Exercise capacity; Iliac venous disease; Preload; Venous obstruction; Venous stenosis.

Fig. 1

A graph depicting Frank-Starling relationship between ventricular end-diastolic volume and stroke volume in the normal heart, and in preload impairment secondary to venous obstruction

Fig. 2

a Simultaneous arterial and venous contrast injection in a therapy resistant hypertensive patient, with no signs or symptoms of leg swelling (LAO). b, c Demonstrate impeded contrast flow in the vein via direct overriding arterial compression from both AP and LAO angles respectively

Fig. 3

Contrast venography demonstrating venous collaterals in post-thrombotic syndrome (a, b). c May-Thurner syndrome in a patient with indwelling IVC filter

Fig. 4

MRV demonstrating hypertrophied azygos, hemiazygos and spinal veins in a patient with previous DVT affecting IVC and iliac veins (a) compared with normal venous anatomy (b). (i) IVC, (ii) aorta, (iii) azygos vein, iv. hemiazygos vein v. spinal collaterals