TITLE: NT-pro-BNP as marker for cardiac strain that may be caused by high-output arteriovenous shunting in a haemodialysis patient. A case report. 

BACKGROUND: An arteriovenous fistula (AVF) is the first choice when considering access for haemodialysis (HD). When a forearm AVF fails an upper arm AVF is a frequent subsequent dialysis access option. The latter may cause cardiac strain. NT-pro-B-type natriuretic peptide (NT-NT-proBNP) is a marker used to estimate volume overload and cardiac strain. This case report shows the benefit of using longitudinal individual follow-up of pre-dialysis NT-proBNP in clinical practice to detect changes in cardiac condition that may be due to high-output AVF.

CASE PRESENTATION: An 18 years old patient performed HD via an upper arm AVF before he was admitted to our unit. NT-proBNP was above the upper detection level of 70,000 ng/L. Echocardiography revealed a left-ventricular cardiac insufficiency. Interdialytic weight gain (IDWG) was above 5%. He was instructed to lower fluid intake and IDWG towards 2%. Four months later NT-proBNP surpassed 70,000 ng/L again. Flow in the brachial artery was at 3034 ml/min. Reconstructive surgery of the AVF did not reduce flow and NT-proBNP in the long run. Clinically, he worsened to NYHA class III-IV. It was decided to close the upper arm AVF and to replace it with a lower arm AVF leading to a reduced artery flow of 1344 mL/min. The clinical condition successively recovered and NT-proBNP decreased to 7000 ng/L.

CONCLUSIONS: Pre-dialysis NT-proBNP should be considered as a suitable routine marker for cardiac strain such as caused by high-output AVF besides variables such as IDWG. Brachial artery flow besides AVF flow measurement is helpful.

SOURCE: Wärja M, Laveborn E, Ott M, et al. NT-pro-BNP as marker for cardiac strain that may be caused by high-output arteriovenous shunting in a haemodialysis patient. A case report[J]. BMC Nephrol, 2020,21(1):544. DOI: 10.1186/s12882-020-02195-9. 

背景：动静脉内瘘（AVF）是考虑使用血液透析（HD）的首选通路。当前臂AVF失败时，上臂AVF是经常进行的后续透析通路的选择。后者可能导致心脏劳损。 NT-pro-B型利尿钠肽（NT-NT-proBNP）是用于估计容量超负荷和心脏劳损的标记物。该病例报告显示了在临床实践中使用透析前NT-proBNP的纵向个体随访来检测可能由于高输出AVF引起的心脏状况变化的好处。

病例介绍：一名18岁的患者在入院前通过上臂AVF进行了HD。 NT-proBNP高于最高检测水平70,000ng / L。超声心动图显示左心室功能不全。透析间增重（IDWG）高于5％。他被建议将体液摄入量和IDWG降至2％。四个月后，NT-proBNP再次超过70,000ng / L。肱动脉流量为3034ml / min。从长远来看，AVF的重建手术不会减少血流和NT-proBNP。临床上，他恶化为NYHA III-IV级。决定关闭上臂AVF并用前臂AVF替换，导致动脉血流减少1344mL / min。临床病情先后恢复，NT-proBNP降至7000ng / L。

结论：透析前NT-proBNP除了IDWG等变量外，还应被认为是由高输出AVF引起的心脏劳损的常规指标。除AVF流量测量外，肱动脉流量也有帮助。

启发：NT-proBNP可以衡量心脏劳损，高流量内瘘可能是心脏劳损的原因之一，需予以重视，动态监测非常重要。