Exposure to contrast media occasionally induces acute renal disturbance, often called contrast-induced nephropathy (CIN).1–3 Although the impairment is transient and function spontaneously recovers in most cases, irreversible damage occurs in some patients, particularly in those with preexisting chronic renal insufficiency (CRI).3,4 The nephrotoxicity of contrast media causes serious limitations in treating coronary artery disease in patients with CRI. Prevention of CIN has been considered to be one of the most important issues for those patients, since this complication has been reported to be closely associated with higher mortality, longer hospital stays, and poorer long-term outcome.4–6 Previous studies have demonstrated that the most significant risk factors for the development of CIN are preexisting renal impairment, the presence of diabetes, and the dose of contrast media used.7,8 Therefore, minimizing the dose of contrast media, in addition to sufficient periprocedural hydration, has been considered to be useful for reducing the risk of CIN, although there is no ultimate method to eliminate CIN.3,5,9 In the case of 2 patients with CRI, we recently succeeded in effective revascularization by percutaneous coronary intervention (PCI) with the use of less than 20 ml of contrast media. In this article, we introduce the various techniques used in PCI, which was performed to minimize the dose of contrast media and to maintain the safety of the procedure. Case #1. The patient was a 73-year-old male who had been treated for an old myocardial infarction, hypertension, and diabetes mellitus. The patient had previously received coronary stenting in the left anterior descending branch (LAD), but had continued to experience anginal attacks. Recent diagnostic coronary angiography, which was performed 1 week prior to the PCI, revealed diffuse stenotic lesions in an obtuse marginal (OM) branch. Exercise stress myocardial scintigraphy also indicated ischemia in the territory of the stenotic branch. Thus, we decided to perform PCI on the diffuse stenotic lesions, although the patient also had diabetic nephropathy (serum creatinine level [Scr]: 2.4 mg/dl, and creatinine clearance [Ccr]: 23.6 ml/minute). He received periprocedural hydration with normal saline at the rate of 80 ml/hour starting 12 hours before the contrast exposure and continuing for 24 hours. Using standard techniques, the right groin was locally anesthetized, and a 6 Fr sheath was inserted into the right femoral artery. A 6 Fr left Judkins guiding catheter was engaged in the left coronary artery. A graduated floppy guidewire called TGV marker (Avantec Vascular Inc., Sunnyvale, California) was gently inserted into the OM branch, and another regular floppy wire was advanced into the side branch (Figure 1B). We initially treated the distal stenotic lesion with a 2 x 10 mm Cutting Balloon (Boston Scientific Corp., Natick, Massachusetts). After confirming sufficient dilatation, we subsequently attempted to treat the proximal lesion of the OM branch. The regular wire placed in the side branch was reinserted into another side branch close to the proximal target lesion. A 2.5 x 23 mm sirolimus-eluting stent Cypher™ stent (Cordis Corp., Miami, Florida) was delivered and inflated to 16 atmospheres. Adjunctive dilatation of the stent was performed with a plain balloon (2.75 x 10 mm) since dilatation was confirmed to be insufficient by intravascular ultrasound (IVUS) using the Invision Gold 3 system (Volcano Therapeutics Inc., Rancho Cordova, California) immediately after stent placement. Throughout the procedure, the positioning of the balloon and the stent was determined by referring to the bifurcation of the wires. Instead of regular angiography, selective angiography with 1.5 ml of contrast media was performed a few times by supplying the contrast media through the tip of a multifunctional probing catheter (Boston Scientific), which was inserted into the proximal portion of the branch along the marker wire (Figure 1C). IVUS was repeatedly performed to confirm the result of each intervention. Because of these efforts to minimize the dose of contrast media, the session was completed with the use of 15 ml of contrast media (iopamidol 350 mg/dl, Daiichi Pharmaceutical Co. Ltd., Japan). The duration of the procedure was approximately 60 minutes, and the total fluoroscopic time was 29 minutes. We were able to achieve optimal revascularization, which was confirmed by both selective angiography (Figure 1C) and IVUS (Figures 2 A and B). After the procedure, the patient was angina-free, and experienced no CIN-associated complications. Case #2. The patient was a 69-year-old female who was transferred to the hospital with severe congestive heart failure associated with an old myocardial infarction. Diagnostic coronary angiography, which was performed 1 week prior to the PCI, showed total occlusion of the distal right coronary artery with a grade II collateral from the left circumflex branch and a long (99%) stenosis through the mid to distal part of the LAD (Figure 3A). Although her renal function was impaired (Scr: 2.8 mg/ml and Ccr: 22.3 ml/minute) due to nephrosclerosis, revascularization of the LAD was considered necessary to improve the status of her heart condition, which was refractory to medical treatment for congestive heart failure. She had been hydrated with normal saline at the rate of 60 ml/hour starting from 12 hours earlier, and also received oral administration of 600 mg of acetylcysteine twice at 12 hours and 1 hour prior to the procedure. Using the standard techniques described in case 1, a 6 Fr left Judkins catheter was engaged in the left coronary artery. Two floppy wires were used; one was gently inserted into the LAD and the other into the diagonal branch starting from the middle of the target lesion. After a series of predilatations with a plain balloon (2 x 20 mm), 3 Cypher™ sirolimus-eluting stents (3.0 x 18 mm, 3.0 x 23 mm, and 2.5 x 23 mm, in that order, from the proximal portion) were vertically deployed in the diffuse stenotic lesion, which was longer than 40 mm. Using PCI, we made the effort to minimize the dose of the contrast, which was similar to the amount used in case 1. Optimal revascularization was confirmed by analysis of the final angiography images (Figures 3B and C) and IVUS. During the procedure, 18 ml of the contrast media (iopamidol 300 mg/dl, Daiichi) was utilized. The duration of the procedure was approximately 70 minutes, and the total fluoroscopic time was 34 minutes. No increase in serum creatinine level was observed after the procedure. Cardiac function greatly improved after revascularization of the LAD, and the patient was able to walk home without any assistance. Discussion To date, there is no definite measure by which the development of CIN can be completely prevented.1–3,5 Recent studies have demonstrated that prophylactic hemodialysis, which until quite recently had been conventionally performed in patients with severe CRI following PCI, does not confer any beneficial effect on renal function and cannot prevent CIN.10,11 The efficacy of hydration with normal saline or sodium bicarbonate has been established as a standard pretreatment for the prevention of CIN, whereas many expected pharmacological interventions (e.g., acetylcysteine) failed to provide consistent efficacy.2,5 The European Society of Urogenital Radiology (ESUR) guidelines have declared “extracellular volume expansion,” “normal saline,” “low or iso-osmolar contrast medium,” and “low dose of contrast medium” as positive measures to prevent CIN.3 To reduce the dose of contrast media during PCI for patients with CRI, it is generally recommended to perform the procedure under biplane fluoroscopy. Scheduling staged, separate coronary procedures is advised to avoid the excessive use of contrast media in each procedure.12 It is also important to limit excessive test injections which are done to confirm the engagement of the catheter in the ostium of coronary artery. Advancing a floppy-tipped guidewire instead of test injections might be helpful to further minimize the dose of contrast media used. Rezkalla has recently reported a case of PCI in a patient with CRI; in this case, the session was guided by IVUS without contrast use.13 Only 5 ml of the contrast media was used to obtain an image after the completion of the entire procedure. However, this method was not applicable to our patients who had more complex stenotic lesions. There was a significant possibility of serious complications such as extravasation when the guidewire crossed through the complex lesions in the distal portion of the branch in the absence of contrast media. During the PCI sessions of our 2 cases, we performed selective angiography from the tip of a small catheter that was placed into the branch. A multifunctional probing catheter, i.e., a micro over-the-wire catheter combined with a monorail segment,14 which was utilized during PCI for case #1, demonstrated particularly excellent performance, since it provided the condition in which manipulation of the guidewire was possible under the guidance of selective angiography. In order to identify the precise location of the target lesion without wasting contrast media, we created a landmark by inserting another guidewire in addition to using the marker wire into the side branch, close to the target lesion. With the application of these techniques to minimize the dose of contrast, both PCI sessions were successfully carried out without any complications by using an acceptable dose of the contrast media (15 ml and 18 ml). Both the duration of the procedure and the total fluoroscopic time during these sessions were comparable with those during regular PCI procedures at our center. The use of alternatives to iodinated contrast is another approach to preventing CIN.3 It has been reported that PCI can be performed with gadolinium contrast agent;15,16 this appears to be a possible alternative method for patients with CRI, although the safety of this agent in the high-risk group such as our 2 patients has not been established.17 A novel method for removing iodine contrast from the coronary sinus has been demonstrated in animal experiments.18 It is anticipated that this method will be transferred to clinical settings. The scoring method for prediction of CIN has been recently demonstrated to stratify the patients according to the risk of CIN after PCI.19 Risk stratification is important in selecting the method of management for preventing CIN following PCI. For high-risk patients, the aforementioned procedural techniques should be fully utilized in addition to the providing sufficient hydration. With the described method using various techniques and devices, PCI was feasible under stringent restrictions on the dose of contrast media used. This procedure is theoretically applicable even for complex lesions, and is expected to contribute to the elimination of CIN in patients with CRI.
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