Author + information
- Giancarlo Marenzi, MD⁎ (, )
- Cristina Ferrari, MD and
- Antonio L. Bartorelli, MD
- ↵⁎Centro Cardiologico Monzino, Via Parea 4, 20138 Milan, Italy
We appreciate the thoughtful comments of Drs. Chauhan and Sharma on our study. We agree with them with regard to the critical importance of generous hydration and positive fluid balance for contrast-induced nephropathy prevention. Current guidelines recommend administration of isotonic electrolyte solutions at an infusion rate of 1.0 ml/kg/h or less (0.5 ml/kg/h) in case of left ventricular ejection fraction <35% or New York Heart Association functional class >2 (1). We believe that this hydration rate represents a “safe” regimen conceived for avoiding fluid overload and pulmonary edema rather than an “effective” patient hydration. Indeed, a 70-ml/h hydration rate for 24 h in a 70 kg fasting patient is the minimal fluid volume needed to avoid dehydration. By contrast, vigorous hydration before coronary procedures is difficult logistically and poorly tolerated, in particular in the presence of impaired cardiac and renal function. Thus, despite general agreement on hydration benefit and strong recommendation of all guidelines, most patients are not sufficiently hydrated in routine clinical practice.
In our study (2), saline infusion and urine output were rigorously measured. However, from these data it is not possible to extrapolate the net fluid balance, because all patients were encouraged to freely drink water after coronary angiography. Thus, it is likely that the control group too had a modestly positive or, at worst, a slightly negative fluid balance.
Although further studies are needed to elucidate the mechanisms of the innovative preventive treatment described in our report, it is unlikely that its beneficial effects might be explained by the initial 250-ml saline bolus only. We believe that simultaneous high urine-flow rate resulting from furosemide administration together with dehydration prevention obtained by exactly matching saline infusion might have played an important role in the results observed in the treated patients. Indeed, preclinical studies demonstrated that prolonged contact time of contrast with the tubular epithelial cells is associated with a greater tubular damage, as indicated by biomarkers (3), and that high urine-flow rates flush the renal tubules and lower contrast concentration in tubular fluid. This accelerates contrast excretion, thus reducing the exposure time of tubular cells. Therefore, the high urine-flow rate achievable with this innovative treatment might lower contrast concentration and viscosity and accelerate contrast excretion, thus reducing the exposure time of tubular cells to its toxicity (4).
- American College of Cardiology Foundation
- Wijns W.,
- Kolh P.,
- Danchin N.,
- et al.,
- Task Force on Myocardial Revascularization of the European Society of Cardiology (ESC) and the European Association for Cardio-Thoracic Surgery (EACTS); European Association for Percutaneous Cardiovascular Interventions (EAPCI)
- Marenzi G.,
- Ferrari C.,
- Marana I.,
- et al.