Functional capillary impairment in patients with ventricular assist devices

Abstract

The implantation of continuous – flow ventricular assist devices (VAD) is suggested to evoke angiodysplasia contributing to adverse events such as gastrointestinal bleeding. We evaluated in vivo capillary density and glycocalyx dimensions to investigate possible systemic microvascular changes in patients with chronic heart failure and VAD support vs. standard medical treatment. Forty-two patients with VAD support were compared to forty-one patients with ischemic and non-ischemic chronic heart failure (CHF) on standard pharmacotherapy and to a group of forty-two healthy subjects in a prospective cross-sectional study. Sublingual microcirculation was visualized using Sidestream Darkfield videomicroscopy and functional and perfused total capillary densities were quantified. Patients with VAD implantation were followed for one year and bleeding events were recorded. Median time after VAD implantation was 18 months. Patients were treated with centrifugal-flow devices (n = 31) or axial-flow devices (n = 11). Median functional capillary density was significantly lower in patients with VAD therapy as compared to CHF patients (196 vs. 255/mm 2 , p = 0.042, adjusted p-value). Functional and total capillary densities were 44% and 53% lower (both p < 0.001) in patients with VAD therapy when compared to healthy subjects. Cox regression analysis revealed loss of capillary density as a significant predictor of bleeding events during one -year follow-up of VAD patients (HR: 0.987, CI (95%): 0.977–0.998, p = 0.021 for functional and 0.992, CI (95%): 0.985–0.999, p = 0.03 for total capillary density). In conclusion, patients with VAD support exhibit capillary density rarefaction, which was associated with bleeding events. If confirmed independently, capillary impairment may be evaluated as novel marker of bleeding risk.

Effects of a single aerobic exercise on perfused boundary region and microvascular perfusion: a field study

“…We were not able to detect an immediate effect on ESL dimensions following aerobic exercise in this study. There was a negative association of PBR and RBC filling percentage at baseline, as has been described in previous studies [9,15,16]. This negative association of PBR and RBC filling percentage was maintained and even more pronounced after aerobic exercise, resulting also in a distinct association between change of PBR and change of RBC filling percentage.…”

“…The change of PBR and RBC filling percentage was calculated by subtracting the baseline from the post-exercise value. The detailed definition of valid and total capillary density is provided elsewhere [ 16 ].…”

Non-pulsatile blood flow is associated with enhanced cerebrovascular carbon dioxide reactivity and an attenuated relationship between cerebral blood flow and regional brain oxygenation

“…CPB, VA-ECMO) or continuous flow left ventricular assist devices (CF LVAD) [14–17]. Flow-induced tissue malperfusion, for example, could therefore potentially further augment ischaemia/reperfusion injury in patients in the course of extracorporeal cardiopulmonary resuscitation (ECPR) and loss of pulsatile cerebral perfusion might contribute to worse neurological outcome [4, 7, 18]. In fact, perfused vessel density, an established microcirculatory parameter, was negatively correlated with survival in patients requiring VA-ECMO due to cardiogenic shock [8].…”

Epilepsy in patients undergoing cardiac surgery with ExtraCorporeal Circulation: case series and description of a peculiar clinical phenotype

“…The potentially harmful effects of ECC on the cerebral circulation are usually associated with a risk of neurological complications such as stroke, bleeding, cognitive dysfunction, and delirium. The ECC flow is non or minimal pulsatile and the PaCO2 level is often higher than usual, negatively affecting the cerebral autoregulation [ 10 , 11 ]. Furthermore, within such a short period of absent pulsatility, a heterogeneous flow in human capillaries ensues.…”