Mohamad Hamady

First-in-man safety evaluation of renal denervation for chronic systolic heart failure: primary outcome from REACH-Pilot study.

BACKGROUND Sympathetic overactivation, is reduced by renal denervation in drug-resistant hypertension. A similar role for renal denervation in heart failure remains unstudied, partly due to the concern about potential concomitant deleterious blood pressure reductions. This pilot study evaluated the safety of renal denervation for heart failure using an intensive follow-up protocol. METHOD 7 patients (mean age 69 years) with chronic systolic heart failure (mean BP on referral 112/65 mmHg) on maximal tolerated heart failure therapy underwent bilateral renal denervation May-July 2011. Patients were admitted for pre-procedure baseline assessments and in-patient observation for 5 days following denervation. Follow-up was weekly for 4 weeks, and then monthly for 6 months. RESULTS No significant haemodynamic disturbances were noted during the acute phase post renal denervation. Over 6 months there was a non-significant trend to blood pressure reduction (Δsystolic -7.1 ± 6.9 mmHg, p=0.35; Δdiastolic -0.6 ± 4.0 mmHg, p=0.88). No hypotensive or syncopal episodes were reported. Renal function remained stable (Δcreatinine -5.7 ± 8.4 μmol/l, p=0.52 and Δurea -1.0 ± 1.0 mmol/l, p=0.33). All 7 patients described themselves as symptomatically improved. The six minute walk distance at six months was significantly increased (Δ=27.1 ± 9.7 m, p=0.03), with each patient showing an increase. CONCLUSIONS This study found no procedural or post procedural complications following renal denervation in patients with chronic systolic heart failure in 6 months of intensive follow-up. Results suggested improvements in both symptoms and exercise capacity, but further randomised, blinded sham-controlled clinical trials are required to determine the impact of renal denervation on morbidity and mortality in systolic heart failure. These data suggest such trials will be safe. ClinicalTrial.gov NCT01584700

Evaluation of robotic endovascular catheters for arch vessel cannulation.

OBJECTIVE Conventional catheter instability and embolization risk limits the adoption of endovascular therapy in patients with challenging arch anatomy. This study investigated whether arch vessel cannulation can be enhanced by a remotely steerable robotic catheter system. METHODS Seventeen clinicians with varying endovascular experience cannulated all arch vessels within two computed tomography-reconstructed pulsatile flow phantoms (bovine type I and type III aortic arches), under fluoroscopic guidance, using conventional and robotic techniques. Quantitative (catheterization times, catheter tip movements, vessel wall hits, catheter deflection) and qualitative metrics (Imperial College Complex Endovascular Cannulation Scoring Tool [IC3ST]) performance scores were compared. RESULTS Robotic catheterization techniques resulted in a significant reduction in median carotid artery cannulation times and the median number of catheter tip movements for all vessels. Vessel wall contact with the aortic arch wall was reduced to a median of zero with robotic catheters. During stiff guidewire exchanges, robotic catheters maintained stability with zero deflection, independent of the distance the catheter was introduced into the carotid vessels. Overall IC3ST performance scores (interquartile range) were significantly improved using the robotic system: Type I arch score was 26/35 (20-30.8) vs 33/35 (31-34; P = .001), and type III arch score was 20.5/35 (16.5-28.5) vs 26.5/35 (23.5-28.8; P = .001). Low- and medium-volume interventionalists demonstrated an improvement in performance with robotic cannulation techniques. The high-volume intervention group did not show statistically significant improvement, but cannulation times, movements, and vessel wall hits were significantly reduced. CONCLUSION Robotic technology has the potential to reduce the time, risk of embolization and catheter dislodgement, radiation exposure, and the manual skill required for carotid and arch vessel cannulation, while improving overall performance scores.

The role of robotic endovascular catheters in fenestrated stent grafting

OBJECTIVE Fenestrated stent grafting has allowed the treatment of complex thoraco-abdominal aneurysm disease via a totally endovascular approach, but the procedure can be technically challenging and time consuming. We investigated whether this procedure may be enhanced by remotely steerable robotic endovascular catheters. METHODS A four-vessel fenestrated stent graft partially deployed within a computed tomography (CT)-reconstructed pulsatile thoraco-abdominal aneurysm silicon model was used. Fifteen operators were recruited to participate in the study and divided into three groups, based on their endovascular experience: group A (n = 4, 100-200 endovascular procedures, group B (n = 5, 200-300), and group C (n = 6, >300). All operators were asked to cannulate the renal and visceral vessels under fluoroscopic guidance, using conventional and robotic techniques. Quantitative (catheterization times and wire/catheter tip movements) and qualitative metrics (procedure-specific-rating scale [IC3ST]), which grades operators on catheter use, instrumentation, successful cannulation/catheterization, and overall performance were compared. RESULTS Median procedure time for cannulation of all four vessels was reduced using the robotic system (2.87 min, interquartile range [IQR; 2.20-3.90] versus 17.24 min [11.90-19.80]; P < .001) for each individual operator, regardless of the level of endovascular experience. The total number of wire/catheter movements taken to complete the task was also significantly reduced (38, IQR [29-57] versus 454 [283-687]; P < .001). There were significant differences in time and movement for cannulation of each individual vessel in the phantom. Robotic catheter operator radiation exposure was negligible as the robotic workstation is remote and away from the radiation source. Overall performance scores significantly improved using the robotic system, despite minimal operator exposure to this technology (IC3ST score 29/35, IQR [22.8-30.7] versus 19/35 [13-24.3]; P = .002). Each group of operators demonstrated an improvement in performance with robotic cannulation. For group A, median IC3ST score was 28/35, IQR (22-33) versus 15/35 (11-20); P = .04; for group B, 30/35 (27-31) versus 19/35 (18-24); P = .07; and for group C, 28.8/35 (28.5-29) versus 22/35 (16-24); P = .06. For groups B and C, these differences did not reach statistical significance. CONCLUSION Robotic catheterization of target vessels during this procedure is feasible and minimizes radiation exposure for the operator. Steerable robotic catheters with intuitive control may overcome some of the limitations of standard catheter technology, enhance target vessel cannulation, reduce instrumentation, and improve overall performance scores.

Robot-assisted Fenestrated Endovascular Aneurysm Repair (FEVAR) Using the Magellan System

A 67-year-old man underwent robot-assisted three-vessel fenestrated endovascular aneurysm repair (FEVAR) for a 7.3-cm juxtarenal aneurysm. The 6-F robotic catheter was manipulated from a remote workstation, away from the radiation source. Robotic cannulation of the left renal artery was achieved within 3 minutes. System setup time was 5 minutes. There were no postoperative complications. Computed tomography angiography performed at discharge and at 4-month follow-up confirmed target vessel patency with no evidence of an endoleak. Selective cannulation of target vessels during FEVAR using this novel technology is feasible. Endovascular robotics may have a role in simplifying complex endovascular tasks and potentially reducing radiation exposure to the operator.

Initial Clinical Application of a Robotically Steerable Catheter System in Endovascular Aneurysm Repair

Purpose: To report the initial clinical use of a robotically steerable catheter during endovascular aneurysm repair (EVAR) in order to assess this novel and innovative approach in a clinical setting. Technique: Following a series of in-vitro studies and procedure rehearsals using a pulsatile silicon aneurysm model, a 78-year-old man underwent robot-assisted EVAR of a 5.9-cm infrarenal abdominal aortic aneurysm. During the standard procedure, a 14-F remotely steerable robotic catheter was used to successfully navigate through the aneurysm sac, cannulate the contralateral limb of a bifurcated stent-graft under fluoroscopic guidance, and place stiff wires using fine and controlled movements. The procedure was completed successfully. There were no postoperative complications, and computed tomographic angiography prior to discharge and at 3 months confirmed that the stent-graft remained in good position, with no evidence of an endoleak. Conclusion: EVAR using robotically-steerable catheters is feasible. This technology may simplify more complex procedures by increasing the accuracy of vessel cannulation and perhaps reduce procedure times and radiation exposure to the patient and operator.

Advanced Catheter Technology: Is This the Answer to Overcoming the Long Learning Curve in Complex Endovascular Procedures

INTRODUCTION Advanced endovascular procedures require a high degree of skill with a long learning curve. We aimed to identify differential increases in endovascular skill acquisition in novices using conventional (CC), manually steerable (MSC) and robotic endovascular catheters (RC). MATERIALS/METHODS 10 novices cannulated all vessels within a CT-reconstructed pulsatile-flow arch phantom in the Simulated Endovascular Suite. Subjects were randomly assigned to conventional/manually-steerable/robotic techniques as the first procedure undertaken. The operators repeated the task weekly for 5 weeks. Quantitative (cannulation times, wire/catheter-tip movements, vessel wall hits) and qualitative metrics (validated rating scale (IC3ST)) were compared. RESULTS Subjects exhibited statistically significant differences when comparing initial to final performance for total procedure times and catheter-tip movements with all catheter types. Sequential non-parametric comparisons identified learning curve plateau levels at weeks 2 or 3(RCs, MSCs), and at week 4(CCs) for the majority of metrics. There were significantly fewer catheter-tip movements using advanced catheter technology after training (Week 5: CC 74 IQR(59-89) versus MSC 62(44-81); p = 0.028, and RC 33 (28-44); p = 0.012). RCs virtually eliminated wall hits at the arch (CC 29(28-76) versus RC 8(6-9); p = 0.005) and produced significantly higher overall performance scores (p < 0.02). CONCLUSION Advanced endovascular catheters, although more intricate, do not seem to take longer to master and in some areas offer clear advantages with regards to positional control, at a faster rate. RCs seem to be the most intuitive and advanced skill acquisition occurs with minimal training. Robotic endovascular technology may have a significantly shorter path to proficiency allowing an increased number of trainees to attempt more complex endovascular procedures earlier and with a greater degree of safety.

In vitro fenestration of aortic stent-grafts: implications of puncture methods for in situ fenestration durability.

Purpose To investigate the quality of stent-graft fenestrations created in vitro using different needle puncture and balloon dilation angles in different commercial endografts. Methods Fenestrations were made in a standardized fashion in 3 different endograft types: Talent monofilament twill woven polyester, Zenith multifilament tubular woven polyester, and Endofit thin-walled expanded polytetrafluoroethylene (PTFE). Punctures were made at 30°, 60°, and 90° angles using a 20-G needle and dilated using 6-mm standard and 7-mm cutting balloons; at least 6 fenestrations were made at each angle with standard balloons and at least 6 with cutting balloons. The 137 fenestrations were examined under light microscopy; quantitative and qualitative digital image analysis was performed to determine size, shape, and fenestration quality. Results PTFE grafts were easier to puncture/dilate, resulting in larger, elliptical fenestrations with overall better quality than the Dacron grafts; however, the puncture/dilation angle made an impact on the shape and quality of fenestrations. A significant number of fabric tears were observed in PTFE fabric at <90° puncture/dilation angles compared to Dacron grafts. In Dacron grafts, fenestration quality was significantly higher with 90° puncture/dilation angles (higher in Talent grafts). Cutting balloon use resulted in significantly more fabric tears and poor quality fenestrations in all graft types. Conclusion Different endografts behave significantly differently when fenestrations are fashioned. Optimum puncture/dilation is important when considering in vivo fenestration techniques. Improvements in instrumentation, materials, and techniques are required to make this a reliable and reproducible endovascular option.

CT evaluation of pulmonary venous anatomy variation in patients undergoing catheter ablation for atrial fibrillation

To characterize pulmonary vein (PV) anatomy and the relative position of the PV ostia to the adjacent thoracic vertebral bodies, two readers reviewed 176 computed tomography pulmonary venous studies. PV ostial dimensions were measured and PV ovality assessed. Anatomical variations in PV drainage were noted. The position of the PV ostium relative to the nearest vertebral body edge was recorded. Right PV ostia were significantly more circular than the left (p<.001). Anatomical variability was greater for right PVs: 82% of patients had 2 ostia, 17% had 3 ostia, 0.5% had 4 ostia and 0.5% a common ostium. For left PVs, 91% of patients had 2 ostia, 8.5% a common ostium and 0.5% 3 ostia. Mean ostial distances from vertebral margin were: right PVs 3.62±7.48 mm; left PVs 3.84±8.46 mm (p=.72). 65% of right upper PV, 60.5% of right lower PV, 51% of left upper PV and 57% of left lower PV ostia were positioned lateral to vertebral bodies. Right PV ostia are rounder than left-sided and right PV drainage is more variable. As a significant proportion of PV ostia overlap the vertebral bodies, prior anatomical evaluation by CT can assist catheter ablation procedures for atrial fibrillation (AF), especially when performed under fluoroscopy.

Reducing Error and Improving Efficiency during Vascular Interventional Radiology: Implementation of a Preprocedural Team Rehearsal

PURPOSE To determine the type and frequency of errors during vascular interventional radiology (VIR) and design and implement an intervention to reduce error and improve efficiency in this setting. MATERIALS AND METHODS Ethical guidance was sought from the Research Services Department at Imperial College London. Informed consent was not obtained. Field notes were recorded during 55 VIR procedures by a single observer. Two blinded assessors identified failures from field notes and categorized them into one or more errors by using a 22-part classification system. The potential to cause harm, disruption to procedural flow, and preventability of each failure was determined. A preprocedural team rehearsal (PPTR) was then designed and implemented to target frequent preventable potential failures. Thirty-three procedures were observed subsequently to determine the efficacy of the PPTR. Nonparametric statistical analysis was used to determine the effect of intervention on potential failure rates, potential to cause harm and procedural flow disruption scores (Mann-Whitney U test), and number of preventable failures (Fisher exact test). RESULTS Before intervention, 1197 potential failures were recorded, of which 54.6% were preventable. A total of 2040 errors were deemed to have occurred to produce these failures. Planning error (19.7%), staff absence (16.2%), equipment unavailability (12.2%), communication error (11.2%), and lack of safety consciousness (6.1%) were the most frequent errors, accounting for 65.4% of the total. After intervention, 352 potential failures were recorded. Classification resulted in 477 errors. Preventable failures decreased from 54.6% to 27.3% (P < .001) with implementation of PPTR. Potential failure rates per hour decreased from 18.8 to 9.2 (P < .001), with no increase in potential to cause harm or procedural flow disruption per failure. CONCLUSION Failures during VIR procedures are largely because of ineffective planning, communication error, and equipment difficulties, rather than a result of technical or patient-related issues. Many of these potential failures are preventable. A PPTR is an effective means of targeting frequent preventable failures, reducing procedural delays and improving patient safety.

Endovascular Repair of an Acute, Mycotic, Ascending Aortic Pseudoaneurysm

This report describes endovascular stenting of an acute mycotic ascending aortic aneurysm. An eighty-three year old lady presented nine weeks after aortic valve surgery and subsequent thyroidectomy with sternal pain secondary to a mycotic ascending aortic pseudoaneurysm. The pseudoaneurysm was visible through the unhealed sternum. Open repair was considered too high a mortality risk. Endovascular stenting was performed using two covered infrarenal proximal extension devices (GORE Excluder Aortic Extender(®), W. L. Gore & Associates, Flagstaff, Arizona, USA) deployed from a right axillary approach utilising overdrive cardiac pacing. Post procedure imaging revealed shrinkage of the pseudoaneurysm sac.