Evaluation of microvascular endothelial function and capillary density in patients with infective endocarditis using laser speckle contrast imaging and video-capillaroscopy

Objective: To evaluate the systemic microcirculation of patients with infective endocarditis (IE). Methods: This is a comparative study of patients with definite IE by the modified Duke criteria admitted to our center for treatment. A reference group of sex- and age-matched healthy volunteers was included. Microvascular flow was evaluated in the forearm using a laser speckle contrast imaging system, for noninvasive measurement of cutaneous microvascular perfusion, in combination with skin iontophoresis of acetylcholine (ACh) and sodium nitroprusside (SNP) to test microvascular reactivity. Microvascular density was evaluated using skin video-capillaroscopy. Results: We studied 22 patients with IE; 15 were male and seven female. The mean age and standard deviation (SD) were 45.5 +/- 17.3 years. Basal skin microvascular conductance was significantly increased in patients with IE, compared with healthy individuals (0.36 +/- 0.13 versus 0.21 +/- 0.08 APU/mmHg; P < 0.0001). The increase in microvascular conductance induced by ACh in patients was 0.21 +/- 0.17 and in the reference group, it was 0.37 +/- 0.14 APU/mmHg (P = 0.0012). The increase in microvascular conductance induced by SNP in patients was 0.18 +/- 0.14 and it was 0.29 +/- 0.15 APU/mmHg (P = 0.0140) in the reference group. The basal mean skin capillary density of patients (135 +/- 24 capillaries/mm(2)) was significantly higher, compared with controls (97 +/- 21 capillaries/mm(2); P < 0.0001). Conclusions: The main findings in the microcirculation of patients with IE were greater basal vasodilation and a reduction of the endothelium-dependent and -independent microvascular reactivity, as well as greater functional skin capillary density compared to healthy individuals.