Quantifying digital vascular disease in patients with primary Raynaud’s phenomenon and systemic sclerosis

In primary and secondary Raynaud’s phenomenon, measurement of activity or severity, or both, of the digital vascular disease is a major challenge. We need to identify objective measures of digital vascular disease that are helpful in predicting those patients with Raynaud’s who have underlying connective tissue disease, and to measure reliably digital vascular disease progression, and responses to treatment. None of the various physiological measurement techniques used in the assessment of patients with primary or secondary Raynaud’s are ideal. In this review we outline these techniques, highlighting their applications and limitations. The discussion concentrates on the physiological assessment of patients with primary Raynaud’s phenomenon (PRP) and systemic sclerosis (SSc), but is also applicable to other connective tissue diseases. We have not included biochemical markers of vascular injury or measurement of tissue oxygen levels. In PRP, episodic ischaemia in response to cold exposure or to emotional stimuli is entirely reversible: absence of tissue damage is a defining feature.1 In contrast, SSc may be associated with irreversible tissue damage with ulceration, scarring and sometimes gangrene, and structural change occurs in the vasculature.2 3 Indeed, SSc is probably primarily a disease of the vasculature, although it is not clear how this interrelates with collagen and other connective tissue matrix metabolism.4 5 Assessment of digital vascular disease needs to take into account: (a) Digital vasospasm. This is best assessed by dynamic testing with standard stimuli, such as a standard cold stress. (b) Structural vascular disease. This may affect basal blood flow in addition to vascular responses to standard stimuli. In the patient presenting with Raynaud’s phenomenon, we must assess both the microvasculature and the digital arteries. Different physiological measurement techniques may be used in combination, especially if investigators wish to examine both digital artery and microvascular flow.6 On widefield capillaroscopy, …