Chandrasekar Santhanakrishnan

Graft Arterial Stenosis in Kidney En Bloc Grafts From Very Small Pediatric Donors: Incidence, Timing, and Role of Ultrasound in Screening

In previous studies with different donor selection criteria and noncontemporary surgical techniques, graft arterial stenosis (GAS) has been reported to occur more frequently in adult recipients of pediatric en bloc renal allografts (EBKT) as compared to single adult donor allografts. The purpose of our study was to evaluate the incidence of GAS within our EBKT recipient population and to evaluate clinical and imaging features of those cases with GAS. In a retrospective cohort study, we analyzed 182 EBKT performed at a single institution. We identified cases of suspected GAS based on clinical factors, lab results, and noninvasive imaging. Diagnosis of GAS was confirmed by digital subtraction angiography. Two EBKT recipients (1.1% of 182) had angiographically confirmed GAS at 2.5 and 4.5 months after transplant. In both cases, the stenoses were short segment within the proximal (perianastomotic) donor aorta, color Doppler ultrasound demonstrated peak systolic velocities of >400 cm/s, and poststenotic parvus tardus waveforms were present. Both patients underwent angioplasty and demonstrated postintervention improvement in renal function and blood pressure. Restenosis did not occur during follow up. In conclusion, recipients of EBKT have a low incidence of GAS, similar to the lowest reported for adult single allografts.

Sonographic Evaluation of Clinically Significant Perigraft Hematomas in Kidney Transplant Recipients

OBJECTIVE The purpose of this study was to assess the sensitivity of ultrasound in evaluating peritransplant hematomas that require surgical evacuation in recipients of kidney transplants. MATERIALS AND METHODS Thirty-four patients who underwent 37 hematoma evacuations underwent ultrasound examinations in the 24 hours before surgical evacuation. The operative reports were evaluated for presence and size of collection, presence of active bleeding at operation, and composition of the hematoma. The clinical findings leading to the ultrasound examination were recorded. Ultrasound examinations were evaluated in consensus by two board-certified and fellowship-trained abdominal radiologists for the presence, size, and echogenicity of the collection; subjective perfusion visualized with color and power Doppler ultrasound; velocities of the renal arteries; and arcuate artery resistive indexes. RESULTS Ten of the 37 imaged hematomas (27%) had either no or small (< 50 mL) fluid collections on ultrasound examination. With sonographic volumetry, the reported intraoperative volumes were underestimated by 46%. The mean arcuate artery resistive index was 0.82 in the superior pole, 0.81 in the mid pole, and 0.78 in the inferior pole of the kidney. A decrease in hemoglobin level was the most sensitive clinical finding for determining the presence of perigraft hematomas. CONCLUSION Our results suggest that gray-scale sonography alone appears to have limited sensitivity in detecting clinically significant peritransplant hematomas and that its use may result in overall underestimates of hematomas.

Pediatric En Bloc Kidney Transplants: Clinical and Immediate Postoperative US Factors Associated with Vascular Thrombosis

Purpose To evaluate clinical and immediate postoperative ultrasonographic (US) risk factors associated with vascular thrombosis of pediatric en bloc kidney grafts. Materials and Methods This institutional review board-approved HIPAA-compliant retrospective study consisted of 195 recipients of pediatric en bloc kidney grafts throughout a 10-year period. The average recipient and donor age was 45 years (range, 7-74 years) and 9 months (range, 0-84 months), respectively. Clinical factors and immediate postoperative US findings were assessed. Categorical variables were evaluated by using the Fisher exact test and linear models with generalized estimating equations. Results Seventeen patients (23 kidneys) experienced thrombotic events. In six patients (eight kidneys), thrombosis occurred intraoperatively. The remaining 11 patients (15 kidneys) received a diagnosis of thrombosis on postoperative days 1-13. Recipients more than 40 years old had a higher incidence of arterial thrombosis than did younger recipients (eight of 62 vs three of 133, respectively; P < .01). Recipients were more likely to develop thrombosis with donor weight less than 5 kg (10 of 52 vs seven of 140 with donor weight of ≥ 5 kg; P < .01), with intraoperative perfusional concern (10 of 21 vs seven of 174 without; P < .01), or with right-sided allograft placement (10 of 64 vs seven of 131 left sided; P = .03). At US of the 15 postoperative thrombotic events, the incidence of thrombosis was greater when donor arterial velocity was less than 100 cm/sec (seven of 56 vs four of 126 with velocity ≥ 100 cm/sec; P = .04). An intrarenal arterial resistive index of less than 0.6 was associated with higher incidence of arterial thrombosis (nine of 123 vs zero of 217, respectively; P = .01). A resistive index greater than 0.8 was associated with a higher incidence of venous thrombosis (four of 13 vs one of 217, respectively; P = .04). Conclusion Clinical factors and immediate US findings can help stratify patients receiving pediatric en bloc kidneys into risk categories for vascular thrombosis that, if proven in prospective studies, could affect immediate postoperative treatment. (©) RSNA, 2015.

Learning Curve for Laparoendoscopic Single-Incision Live Donor Nephrectomy: Implications for Laparoendoscopic Practice and Training

BACKGROUND The learning curve for laparoendoscopic single-incision live donor nephrectomy, which is technically more complex than the multiport, conventional laparoendoscopic approach, is unknown. PATIENTS AND METHODS In a retrospective cohort study, we analyzed the learning curve of the initial 114 consecutive single-incision laparoendoscopic nephrectomies performed in nonselected live kidney donors. RESULTS Median donor body mass index was 26 kg/m2 (range 20-34). In all, 92% of the nephrectomies were performed on the left side; 18% of the recovered kidneys had multiple renal arteries. Cumulative sum (CUSUM) analysis of operating time (OT) demonstrated that the learning curve was achieved after case 61. For the learning curve phase (Group 1 [cases 1-61]) vs the postlearning phase (Group 2 [cases 62-114]), the difference of the mean OT was 20 minutes (p = 0.05). Mean warm ischemic time in the donors was significantly longer during the learning phase (Group 1, 6 minutes; Group 2, 5 minutes; p = 0.04). Rates of conversions to multiport procedures and of donor complications were not significantly different between Groups 1 and 2. For the recipients, we observed delayed graft function in 2 (2%) cases, no technical graft losses; and 1-year death-censored graft survival was 100% (p = n.s. for all comparisons of Group 1 vs 2). CONCLUSIONS Single-incision laparoendoscopic donor nephrectomy had a long learning curve (>60 cases), but resulted in excellent donor and recipient outcomes. The long learning curve has significant implications for the programs and surgeons who contemplate transitioning from multiport to single-incision nephrectomy. Furthermore, our observations are highly relevant for informing the development of training requirements for fellows to be trained in single-incision laparoendoscopic nephrectomy.

Pediatric en bloc kidney transplantation from very small (≤10 kg) donation after circulatory death (versus brain death) donors: Single-center matched-pair analysis of 130 transplants

En bloc kidney transplants (EBK) from very small pediatric donation after circulatory death (DCD) donors are infrequent because of the perception that DCD adversely impacts outcomes. We retrospectively studied 130 EBKs from donors ≤10 kg (65 consecutive DCD vs 65 donation after brain death [DBD] transplants; pair‐matched for donor weight and terminal creatinine, and for preservation time). For DCD vs DBD, median donor weight was 5.0 vs 5.0 kg; median recipient age was 57 vs 48 years (P = .006). Graft losses from thrombosis (DCD, 5%; DBD, 7%) or primary nonfunction (DCD, 3%; DBD, 0%) were similar in both groups (P = .7). Delayed graft function rate was higher for DCD (25%) vs DBD (14%) (P = .2). Graft survival (death‐censored) for DCD vs DBD at 5 years was 87% vs 91% (P = .3). Median estimated GFR (mL/min per 1.73 m2) was significantly lower for DCD recipients at 1 and 3 months; at 6 years it remained stable at 100 (DCD) and 99 (DBD). DCD impacted early posttransplant graft function, but did not appear to impart added risk for graft loss and long‐term function. Very small (≤10 kg) DCD EBK donors should be considered as an option to augment the deceased kidney donor pool; larger studies with longer follow‐up must confirm these findings.