Discussions
At present, the pathophysiological mechanism of CIN was not fully clear,
which might be involved by multiple factors, including the direct
toxicity of contrast agent on the kidney, renal hemodynamic changes and
oxidative stress reaction, inflammation, and renal tubular obstruction,
etc8-10. Contrast agent cloud induce that vacuoles
formation, intracellular Ca2 + overload and adenosine
triphosphate decreased in renal tubular epithelial cells, thus inducing
apoptosis. There were two-phase effects of contrast agent on renal
hemodynamics. Firstly, the application of contrast agent lead to renal
vascular dilatation that mediators were consequently released. For
example, endoderin stimulated progressive and continuous contraction of
renal vessels, thereby leading to eGFR declining11.
The generation of reactive oxygen species and oxygen free radicals
increased dramatically. After binding with some amino acid residues of
tissue proteins, proteins were easy to be hydrolyzed, polymerized and
cross-linked, which affected the structure and function of cells and
lead to oxidative stress reaction. Secondly, when contrast agents were
filtered through the glomerulus into the renal tubules, they were
viscous as a result of the absence of water in the tubules, which might
lead to tubules obstruction and aggravate renal
damage12. In this study, results showed that dosage of
contrast agent had a positive association with CIN, which was similar to
the previous studies13,14.
Studies had shown that the use of IABP as adjuvant therapy of PCI could
effectively improve renal blood perfusion and have protective effects on
renal function, which markedly reduced the incidence of postoperative
renal insufficiency15,16. In this study, we found that
the values of eGFR were significantly lower in the IABP duration ≤4 days
group as compared to the IABP duration>4 days group in the
three time section of IABP implantation. However, there were no
significant differences in the values of eGFR, SCr among three time
section of IABP implantation in any group. It manifested that IABP
contributed to increase the patient’s urine output and improve serum
creatinine level as soon as possible, which were conducive to reduce the
occurrence of renal insufficiency and protect the patient’s kidney
function.
AMI complicating pump failure was common in patients that areas of
myocardial infarction accounted for more than 40% of the left
ventricle, which significantly influenced cardiac pumping function. The
aggravation of left ventricular filling pressure strengthened the
myocardial oxygen consumption. Eventually, interaction of myocardial
hypoxia, pump failure and myocardial ischemia necrosis developed into
cardiac shock17. IABP using could alleviate the burden
of the left ventricle and improve cardiac function through reducing left
ventricular ejection resistance. Studies have shown that IABP enhanced
the pulsation of coronary arteries and provided pulsed blood flow, which
were beneficial to reduce the occurrence of acute occlusion and no
reflow after PCI treatment18.
In this study, the duration of using IABP was not obviously related to
incidence of 12-month MACEs and all-cause mortality. This reason might
be explained that the patients with AMI complicating pump failure was in
a state of severe ischemia, hypoxia, or even necrosis. Consequently, the
perfusion of important organs suffered serious damage. At this time,
IABP therapeutic therapy was often ineffective. Especially, elderly
patients with AMI complicating CS were more likely to be complicated by
vital organ dysfunction. There were more complications and higher
mortality rates when they underwent IABP adjuvant therapy. A study
indicated that the clinical implications were significantly increased
with IABP using for more than two days19.
Several limitations should be recognized in this study. First, in
consideration of patient safety, the control group without IABP
treatment was not set up. Secondly, due to the lack of long-term
follow-up data, the follow-up time could be appropriately extended and
the long-term prognosis of patients could be further analyzed in detail.
Finally, this study was a single-center, retrospective study, and the
sample size was small, so the results of this study should be
interpreted with caution.
In conclusion, longer duration of IABP implantation was beneficial to
renal function, but was not significantly correlated with the incidence
of 12-month MACEs and all-cause mortality in patients with AMI
complicating pump failure. Patients undergoing PCI or CABG should notice
that the potential damage of high dose of contrast agents on the renal
function.
Acknowledgements The authors are grateful to thank all those
who contributed to the study design and implementation.
Informed consent All participants provided informed consent,
and approval to conduct the survey.
Ethical approval This study was granted by the Research Ethics
Committee of University of Science and Technology of China.
Conflict of interest Statement The authors declare that they
have no conflict of interest.