Peter Minko

Risk factors for nonocclusive mesenteric ischemia after elective cardiac surgery.

OBJECTIVE Nonocclusive mesenteric ischemia (NOMI) may occur after cardiopulmonary bypass. It is crucial to early identify patients who are at risk of developing this complication. The aim of this prospective study was to evaluate perioperative risk factors in a large cohort of patients undergoing elective cardiac surgery. METHODS From January 1, 2010, to March 31, 2011, all patients scheduled for elective cardiac surgery were screened for participation in this trial. If NOMI was suspected, arterial angiography was performed. NOMI and non-NOMI patients were compared with respect to all variables assessed in this study. Additionally, odds ratios were calculated. Linear discriminant analyses as well as logistic regression analyses were performed to develop a model that identifies patients at risk for developing NOMI. RESULTS Eight hundred sixty-five patients were included in the study, of whom 78 developed NOMI. Among preoperative parameters, renal insufficiency, diuretic therapy, and age >70 years showed the highest odds ratios for postoperative NOMI. The highest odds ratios for development of NOMI were observed with postoperative variables. In particular, the need for intra-aortic balloon pump support and serum lactate concentrations >5 mmol/L proved to be serious risk factors. Using a linear discriminant analysis with 7 variables, 92.3% of patients were correctly classified (sensitivity 76.9%, specificity 93.8%). CONCLUSIONS A high index of suspicion for NOMI in patients with the above-mentioned risk factors may decrease the diagnostic and therapeutic delay. To identify at-risk patients the developed risk equation is a useful tool with a high specificity.

Paclitaxel-coated balloon angioplasty for symptomatic central vein restenosis in patients with hemodialysis fistulas.

Purpose: To report a retrospective observational analysis of standard balloon angioplasty (BA) vs. paclitaxel-coated balloon angioplasty (PCBA) for symptomatic central vein restenoses in patients with impaired native hemodialysis fistulas. Methods: A retrospective review was conducted of 27 consecutive patients (15 men; mean age 66±13.8 years, range 39–90) with 32 central vein stenoses (CVS; 6 axillary, 11 subclavian, 12 brachiocephalic, and/or 3 superior caval veins) treated successfully using BA. Freedom from reintervention after BA of de novo lesions was 7.4±7.9 months (range 1–24). Twenty-five (92.6%) patients developed symptomatic restenoses and were treated one or more times by BA (n=32) or PCBA (n=20) using custom-made paclitaxel-coated balloons (diameter 6–14 mm). Results: Technical (<30% residual stenosis) and clinical (functional fistula) success rates for the initial and secondary angioplasty procedures were 100%. No minor/major procedure-associated complications occurred. Mean follow-up was 18.4±17.5 months. Kaplan-Meier analysis for freedom from target lesion revascularization (TLR) found PCBA superior to BA (p=0.029). Median freedom from TLR after BA was 5 months; after PCBA, >50% of patients were event-free during the observation period (mean freedom from TLR 10 months). Restenosis intervals were prolonged by PCBA (median 9 months) vs. BA (median 4 months; p=0.023). Conclusion: Paclitaxel-coated balloon angioplasty of central vein restenosis in patients with hemodialysis shunts yields a statistically significant longer freedom from TLR compared to standard balloon angioplasty.

Atherectomy of heavily calcified femoropopliteal stenotic lesions.

PURPOSE To investigate 1-year outcomes after atherectomy in patients with peripheral arterial disease (PAD) and heavily calcified stenotic lesions. MATERIALS AND METHODS Thirty-eight patients (mean age, 70 y ± 8; 24 men; TransAtlantic Inter-Society Consensus B-D disease; mean lesion length, 7.5 cm ± 3.5) with PAD (Rutherford score of 2-6) were included in this prospective study. In total, 42 calcified lesions of the superficial femoral artery (SFA) or popliteal artery were treated with the SilverHawk atherectomy device. Thirty-two lesions were located in the proximal or distal 3 cm of the SFA or in the popliteal artery, which were considered segments exposed to high biomechanical stress. Patients were followed up after 6 and 12 months. Clinical reevaluation included measurement of ankle-brachial index (ABI) and duplex sonography. RESULTS The primary success rate of the procedure was 88%. In five cases, additional balloon angioplasty and/or stent implantation was necessary. Procedure-related embolization occurred in three cases and was treated by aspiration. The mean Rutherford score decreased significantly from 4.1 ± 1.0 to 1.0 ± 1.3 after 12 months. At the same time, the ABI increased significantly from 0.7 ± 0.3 to 0.9 ± 0.3. The primary patency rate was 69% after 1 year. CONCLUSIONS Atherectomy might be considered as an alternative approach in patients with PAD who have heavily calcified stenotic lesions, especially in areas with high biomechanical stress, where stent implantation is undesirable. Results after 1 year demonstrated a significant decrease of Rutherford score, an increase in ABI, and a reasonable patency rate.

Elevated procalcitonin in patients after cardiac surgery: a hint to nonocclusive mesenteric ischemia.

BACKGROUND Nonocclusive mesenteric ischemia (NOMI) can occur after cardiac surgery, commonly in conjunction with use of cardiopulmonary bypass. Some evidence suggests that serum procalcitonin (PCT) levels are increased in patients with mesenteric ischemia; however, an association between PCT and NOMI has not yet been studied. The current study investigates whether elevated serum PCT levels are found in patients exhibiting NOMI. METHODS In an observational cohort study of 865 patients undergoing elective cardiac surgery, 78 experienced NOMI. Preoperative and postoperative PCT levels were determined by means of enzyme-linked immunosorbent assay. Odds ratios and 95% confidence intervals were calculated by logistic regression analyses to predict accuracy of PCT in identifying patients with NOMI. Additional models were calculated, adjusting for potential confounders. RESULTS Patients with NOMI had higher postoperative PCT levels than control patients (20.8 ± 3.2 ng/mL versus 2.3 ± 1.1 ng/mL; p < 0.001). Likelihood of experiencing NOMI increased with each nanogram per milliliter rise in postoperative PCT level (odds ratio, 2.61; 95% confidence interval, 2.05 to 3.32). Receiver operating characteristic analyses showed elevated serum PCT levels to accurately predict occurrence of NOMI (optimal cutoff value, 6.6 ng/mL; area under the curve, 0.94; sensitivity, 71%; specificity, 94%). CONCLUSIONS Postoperative measurement of PCT seems useful to improve the clinical and noninvasive identification of patients with NOMI after cardiac surgery.

Endoscopic Lung Volume Reduction Using Endobronchial Valves in Patients with Severe Emphysema and Very Low FEV1

Background: Patients with a forced expiratory volume in 1 s (FEV1) below 20% of the predicted normal values (pred.) and either homogeneous emphysema or low diffusing capacity for carbon monoxide (DLCO) have a high risk for adverse events including death when undergoing surgical lung volume reduction. Objectives: We hypothesized that selected patients can benefit from endoscopic lung volume reduction (eLVR) despite a very low FEV1. Methods: This study is a retrospective analysis of consecutive patients with severe airflow obstruction, an FEV1 ≤20% of pred., and low DLCO who were treated by eLVR with endobronchial valves (EBV) between June 2012 and January 2015. Pre- and postinterventional lung function parameters, the 6-min walking test (6-MWT) distance, adverse events, and follow-up were recorded. Results: In 20 patients, there was an overall improvement in lung function with an increase in FEV1 (16.97-21.03% of pred.) and a decrease in residual volume (322-270% of pred.) and total lung capacity (144-129.06% of pred.). The 6-MWT distance improved (from 239 ± 77 to 267± 97 m overall, and from 184 ± 50 to 237 ± 101 m if patients developed an atelectasis of the target lobe). Pneumothorax occurred in 5 of the 20 patients (25%). 30-day mortality was 0%, and all patients survived to discharge. Conclusions: The patients benefitted moderately from EBV treatment despite an initially low FEV1. Some patients improved remarkably. EBV treatment in patients with an FEV1 ≤20% of pred. is generally feasible and safe. The greatest risk is pneumothorax with prolonged chest tube duration.

Bilateral Endoscopic Lung Volume Reduction in Patients with Severe Emphysema

Reducing hyperinflated areas in chronic obstructive pulmonary disease, either surgically or endoscopically, leads to improvement of functional parameters. It is unclear if bilateral treatment with endobronchial valves (EBV) aiming at total lobar occlusion is beneficial. The aim of this study was to assess the results after staged bilateral endoscopic treatment with EBV. This is a retrospective analysis of patients with severe airflow obstruction, who were treated bilaterally with EBV in two stages, aiming at subsequent atelectasis. Pre- and postintervention lung function parameters, the 6-minute walk test (6-MWT), complications, and follow-up were recorded. Sixteen patients were treated bilaterally in two stages. There was an overall improvement in lung function from baseline to second-treatment follow-up with an increase in FEV1 (23.57-29.21% of predicted) and a decrease in residual volume (299.21-240.10% of predicted) and total lung capacity (140.78-128.71% of predicted). The 6-MWT improved up to 54 m. After each procedure, 9 of 16 patients (56.25%) developed an atelectasis of the target lobe. Overall, pneumothorax occurred in 8 of 32 procedures (25%). No patient died. Patients benefitted from the first EBV treatment. The second treatment did not lead to marked improvements compared to the first treatment. Bilateral lung volume reduction with valves is possible; however, the current results seem not to justify bilateral valve treatment as a routine approach.

Influence of Respiratory Position on Contrast Attenuation in Pulmonary CT Angiography: A Prospective Randomized Clinical Trial

OBJECTIVE The purpose of this study was to prospectively compare the effect of inspiration and resting expiratory position on contrast enhancement in pulmonary CT angiography (CTA) in a randomized clinical trial. SUBJECTS AND METHODS In accordance with a power analysis performed before the study, we included 28 consecutive patients referred for evaluation of suspected pulmonary embolism in this prospective study. Patients were randomly assigned to perform either inspiration (n = 14; six men, eight women; mean age [SD], 38.1 ± 9.8 years) or resting expiratory position (n = 14; six men, eight women; mean age: 42.1 ± 9.2 years). All patients were scanned in a standardized supine position and scanning parameters were kept constant. Contrast medium was injected automatically with bolus tracking. Objective pulmonary vessel attenuation was quantified with digital measurement. Results were analyzed by using the unpaired t test and chi-square test. RESULTS Patients in the resting expiratory position showed significantly higher contrast attenuation than those who performed inspiration (302.9 ± 11.9 HU vs 221.5 ± 20.9 HU; p < 0.01). There were no significant differences in applied total volume of contrast agent (76.8 ± 1.9 mL vs 75.7 ± 1.6 mL; p = 0.6765), total volume including normal saline bolus (116.8 mL ± 2.8 mL vs 121.8 mL ± 2.3 mL; p = 0.1724) or flow rate (3.1 mL/s ± 0.1 mL/s vs 3.2 mL/s ± 0.1 mL/s). CONCLUSION Pulmonary CTA should be performed in the resting expiratory position, and patients should be instructed to avoid inspiration to achieve the highest possible attenuation in the pulmonary arteries.

Subintimal Revascularization of Chronic Iliac Artery Occlusions using a Reentry-Catheter

PURPOSE To demonstrate the value of a Reentry-Catheter for true lumen access after subintimal revascularization of chronic iliac artery occlusions. MATERIALS AND METHODS Subintimal revascularization was performed in 5 patients (mean age: 67 ± 12 years; female: 3, male: 2) with total iliac artery occlusion (TASC B to D), but without gaining access to the true lumen distal to the occlusion. Subsequently, a Reentry-Catheter was used to establish reentry and a new subintimal tract. Patients were followed up after 6, 12 and 24 months for clinical re-evaluation to determine the Rutherford score and the ankle brachial index (ABI). In addition, duplex ultrasound was performed to evaluate vessel patency. RESULTS The primary technical success rate was 100 %. In all cases angioplasty was followed by stent placement to establish the subintimal tract. The mean Rutherford score decreased from 3.6 ± 0.9 to 0.33 ± 0.57 after 24 months, while the ABI increased from 0.67 ± 0.06 to 1.2 ± 0. Vessel patency was observed in all patients available for follow-up examinations. CONCLUSION The Reentry-Catheter reliably allowed access to the true lumen after subintimal revascularization of occluded iliac arteries. Results in this small patient cohort showed a significant reduction in the Rutherford score, increase in the ABI, and a good patency rate after two years.

Abdominal imaging dose in radiology and radiotherapy – Phantom point dose measurements, effective dose and secondary cancer risk

PURPOSE To compare abdominal imaging dose from 3D imaging in radiology (standard/low-dose/dual-energy CT) and radiotherapy (planning CT, kV cone-beam CT (CBCT)). METHODS Dose was measured by thermoluminescent dosimeters (TLDs) placed at 86 positions in an anthropomorphic phantom. Point, organ and effective dose were assessed, and secondary cancer risk from imaging was estimated. RESULTS Overall dose and mean organ dose comparisons yield significantly lower dose for the optimized radiology protocols (dual-source and care kV), with an average dose of 0.34±0.01 mGy and 0.54±0.01 mGy (average ± standard deviation), respectively. Standard abdominal CT and planning CT involve considerably higher dose (13.58 ± 0.18 mGy and 18.78±0.27 mGy, respectively). The CBCT dose show a dose fall-off near the field edges. On average, dose is reduced as compared with the planning or standard CT (3.79 ± 0.21 mGy for 220° rotation and 7.76 ± 0.37 mGy for 360°), unless the high-quality setting is chosen (20.30 ± 0.96 mGy). The mean organ doses show a similar behavior, which translates to the estimated secondary cancer risk. The modelled risk is in the range between 0.4 cases per million patient years (PY) for the radiological scans dual-energy and care kV, and 300 cases per million PY for the high-quality CBCT setting. CONCLUSIONS Modern radiotherapy imaging techniques (while much lower in dose than radiotherapy), involve considerably more dose to the patient than modern radiology techniques. Given the frequency of radiotherapy imaging, a further reduction in radiotherapy imaging dose appears to be both desirable and technically feasible.

Mechanical Thrombectomy of Iliac Vein Thrombosis in a Pig Model Using the Rotarex and Aspirex Catheters

PurposeTo investigate the efficacy and safety of mechanical thrombectomy for iliac vein thrombosis using Rotarex and Aspirex catheters in a pig model.Materials and MethodsIliac vein thrombosis was induced in six pigs by means of an occlusion-balloon catheter and thrombin injection. The presence of thrombi was verified by digital subtraction angiography (DSA) and computed tomography (CT). Thrombectomy was performed using 6F and 8F Rotarex and 6F, 8F, and 10F Aspirex catheters (Straub Medical AG, Wangs, Switzerland). After intervention, DSA and CT were repeated to evaluate the efficacy of mechanical thrombectomy and to exclude local complications. In addition, pulmonary CT was performed to rule out pulmonary embolism. Finally, all pigs were killed, and iliac veins were dissected to perform macroscopic and histological examination.ResultsThrombus induction was successfully achieved in all animals as verified by DSA and CT. Subsequent thrombectomy lead to incomplete recanalization of the iliac veins with residual thrombi in all cases. However, the use of the 6F and 8F Rotarex catheters caused vessel perforation and retroperitoneal hemorrhage in all cases. Application of the Aspirex device caused one small transmural perforation in a vessel treated with a 10F Aspirex catheter, and this was only seen microscopically. Pulmonary embolism was detected in one animal treated with the Rotarex catheters, whereas no pulmonary emboli were seen in animals treated with the Aspirex catheters.ConclusionThe Aspirex catheter allowed subtotal and safe recanalization of iliac vein thrombosis. In contrast, the use of the Rotarex catheter caused macroscopically obvious vessel perforations in all cases.