Influence of non pulsatile systemic circulation on tissue blood flow and oxygen metabolism

Curative surgery for gastric cancer in a patient with an implantable left ventricular assist device

The number of patients with end-stage heart failure treated by a left ventricular assist device (LVAD) is dramatically increasing, because the LVAD has been widely accepted for its clinical results. According to the initiation of destination therapy, the prevalence of malignancy in patients with an LVAD is estimated to increase. In patients with LVADs, abdominal surgery for visceral malignancy is associated with technical difficulties because of the presence of an LVAD pump or the driveline which is located transversely in the preperitoneal space. Herein, we describe the technical management for complete resection of gastric cancer in a patient with an LVAD.

Choroidal Microcirculation in Patients With Rotary Cardiac Assist Device

BACKGROUND

In recent years, fully implanted rotary blood pumps have been used for long-term cardiac assist in patients with end-stage heart failure. With these pumps, the pulsatility of arterial blood flow and arterial pressure pulse is considerably reduced. Effects on end-organ perfusion, particularly microcirculation, have been assessed.

METHODS

The ocular choroid offers a unique opportunity to study the pulsatile component of blood flow by measurement of fundus pulsation amplitude (FPA) as well as the microcirculation by laser Doppler flowmetry. Both techniques were applied in three male patients with rotary pumps (MicroMed DeBakey VAD), in whom pump velocity was adjusted to four levels of flow between individual minimal need and maximal support. In addition, blood flow velocities in the ophthalmic artery (peak, end-diastolic and mean flow velocity--PSV, EDV and MFV, respectively) were measured using color Doppler imaging.

RESULTS

Systolic blood pressure increased by 6 to 22 mm Hg with increasing support. At maximal support FPA was reduced by -60% to -52% as compared with minimal pump support. Blood flow in the choroidal microvasculature, however, did not show relevant changes. A reduction in PSV (-31%, range -47% to -21%) and a pronounced rise in EDV (+93%, range +28% to +147%) was observed, whereas MFV was independent of pump flow.

CONCLUSIONS

Our data indicate that mean choroidal blood flow is maintained when pump support is varied within therapeutic values, whereas the ratio of pulsatile to non-pulsatile choroidal flow changes. This study shows that, in patients with ventricular assist devices, a normal perfusion rate in the ocular microcirculation is maintained over a wide range of support conditions.

Effect of latanoprost 0.005% and brimonidine tartrate 0.2% on pulsatile ocular blood flow in normal tension glaucoma

AIM

To determine the effect of brimonidine tartrate 0.2% and latanoprost 0.005% on pulsatile ocular blood flow (POBF) in patients with normal tension glaucoma (NTG).

METHOD

NTG patients with progressive optic neuropathy, new disc haemorrhage, or field defects that threatened fixation were enrolled into a randomised, investigator masked, crossover study. Group I patients received 4 weeks each of latanoprost, lubricant, and brimonidine, while group II patients received 4 weeks each of brimonidine, lubricant, and latanoprost. Diurnal POBF was measured at baseline and after each 4 week treatment.

RESULTS

25 patients completed the study and had reliable POBF measurement at each visit. There was no significant diurnal change in baseline POBF (p = 0.768). Latanoprost increased POBF by 213 (SD 257) micro l/min (22.8%, p <0.001) while brimonidine increased it by 97 (183) micro l/min (10.4%, p = 0.014). POBF increased at 8 am (p = 0.004), 12 noon (p = 0.002), and 4 pm (p <0.001) with latanoprost, while it increased only at 8 am (p = 0.016) with brimonidine. After adjusting for the factor of IOP, neither latanoprost nor brimonidine increased POBF significantly.

CONCLUSIONS

Latanoprost increases the mean POBF that is related to its IOP lowering effect. The increase in POBF noted after brimonidine is within the range of long term variation and may not be attributable to the drug effect.

Acute effect of latanoprost on pulsatile ocular blood flow in normal eyes

PURPOSE

To determine the effect of an acute dose of 0.005% latanoprost on intraocular pressure and pulsatile ocular blood flow in normal eyes.

METHODS

Nineteen volunteers received a single dose (two drops) of latanoprost 0.005% in one eye and placebo in the fellow control eye, randomized and masked to the observer. Intraocular pressure, perfusion pressure, pulsatile ocular blood flow, and systemic circulatory parameters were measured before and 8 hours after dosing.

RESULTS

The mean (+/- SE) intraocular pressure, perfusion pressure, and pulsatile ocular blood flow before treatment were 17 +/- 1 mm Hg, 46 +/- 3 mm Hg, and 13 +/- 1 microl per second, respectively, in both the treated and control eyes. The mean intraocular pressure reduction was 4.9 and 2.1 mm Hg (28% and 12%) in the treated and fellow eye, respectively. The mean perfusion pressure increase was 5.6 and 2.8 mm Hg (12% and 6%) in the treated and fellow eye, respectively. The mean pulsatile ocular blood flow increase was 2.7 and 0.2 microl per second (20% and 1%) in the treated and fellow eye, respectively. The treated eye change in pulsatile ocular blood flow was not correlated to the change in perfusion pressure. Simultaneous reduction of intraocular pressure and increase or no significant change in pulsatile ocular blood flow occurred in 15 of 19 (79%) of the treated eyes. The systemic blood pressure and pulse rates remained in normal ranges over the 8-hour period.

CONCLUSION

In this study, topical latanoprost significantly reduces intraocular pressure and increases ocular blood flow in normal eyes 8 hours after dosing. These effects of latanoprost may be beneficial in the management of glaucoma patients.