In vitro effect of sodium nitrite on platelet aggregation in human platelet rich plasma--preliminary report

OBJECTIVE

The role of nitrates and nitric oxide on platelet functions has obtained an increasing attention with respect to their potential effects on cardiovascular disorders. In this study we aimed to analyze the effect of sodium nitrite on platelet functions in human platelets.

PATIENTS AND METHODS

This in vitro study was designed to show the effect of sodium nitrite on platelet functions in seven healthy volunteers. Blood samples were centrifuged to prepare platelet rich plasma and platelet poor plasma. Platelet rich plasma was diluted with the platelet poor plasma to have a final count of 300,000 ± 25,000 platelets. Platelet rich plasma was incubated with six different increasing doses (from 10 μM to 5 mM) of sodium nitrite for 1 hour at 37°C. Then stimulating agents including collagen (3 μg ml-1), adenosine diphosphate (10 μM), and epinephrine (10 μM) were added to the cuvette. Changes in light transmission were observed for 10 minutes. In addition spontaneous aggregation were performed in control group with all aggregating agents separately.

RESULTS

Effect of sodium nitrite on agonist-induced platelet aggregation depends on the concentration of sodium nitrite. Compared with control group, agonist-induced platelet aggregations were significantly suppressed by sodium nitrite at the concentration of 5, 1.0 and 0.5 mM.

CONCLUSIONS

Our results suggested that sodium nitrite has inhibitory effects in vitro on platelet aggregation in a dose-dependent manner.

New probing and warm-wash-out technique improves early patency rates in arteriovenous fistula surgery

OBJECTIVE

Arteriovenous fistulas (AVFs) are commonly used during hemodialysis. Early failure of AVFs is quite common with incidence of 43% to 63%. In this study we aimed to describe a novel approach to AVF surgery for improving early patency rates.

PATIENTS AND METHODS

Patients were divided into two groups according to use of probing and warm-wash-out technique. Group I consisted of 31 patients with additional probing technique. Group II consisted of 32 patients without additional maneuver. End-to-side anastomosis were used to all patients. Technical success was defined as having palpation of a thrill on fistula. Flow rates of draining vein was measured at 1st hour, 24th hour, 1st week and 3rd week of surgery.

SURGICAL TECHNIQUE

Classical maneuvers were performed until end of the anastomosis. At this time, vein lumen was washed by low-dosed heparinized warm fluid, with assistance of a simple catheter.

RESULTS

Technical success was similar in both groups at 1st hour and 24th hour, while there were significantly differences between groups at 1st week (p = 0.042) and 3rd week (p = 0.05) assessments. Flow rates were also measured significantly higher in Group I at 1st hour (p = 0.011) and 24th hour (p = 0.016). Flow rates were almost similar in two groups at 1st and 3rd weeks but overall success rate was higher in Group I comparing with Group II (96.8% vs. 81.3%, respectively, p = 0.05).

CONCLUSIONS

Probing and warm-wash out technique will simply increase the surgical success and flow rate of draining vein.

Pre-emptive stellate ganglion block increases the patency of radial artery grafts in coronary artery bypass surgery

BACKGROUND

We evaluated the role of pre-emptive stellate ganglion block (SGB) in preventing radial artery spasm and increasing radial artery graft patency in patients undergoing off-pump coronary artery bypass surgery.

METHODS

In this prospective randomized study, 100 patients were divided into two equal groups (n= 50). In group A, SGB was achieved using 10 ml of ropivacaine and, in group B, SGB was not performed. Radial artery blood flow was measured pre- and intra-operatively. Post-operative clinical determinants (S-T segment elevation, use of inotropic agents, incidence of atrial fibrillation) were recorded. Early coronary angiography was performed.

RESULTS

According to blood flowmeter measurements, the radial artery blood flow was significantly increased in patients with SGB. The incidence of atrial fibrillation, the need for inotropic agents and S-T segment elevation were all decreased in the SGB group. Angiographic intervention revealed that the incidence of graft spasm was also lower in the SGB group.

CONCLUSION

Pre-emptive SGB is an effective method for increasing radial artery blood flow and preventing radial artery spasm. Complications related to radial artery spasm may be decreased and patients may have a more comfortable post-operative period with this method.