A randomised controlled study comparing conventional and magnetic guidewires in a two-dimensional branching tortuous phantom simulating angulated coronary vessels.

OBJECTIVES: To directly compare the magnetic navigation system (MNS) guidewires with conventional guidewires in branching tortuous phantoms with operators of varying MNS and percutaneous coronary intervention experience. BACKGROUND: Vessel tortuosity, angulation, and side branches remain limiting factors in coronary interventions. The MNS addresses these limitations by precisely directing the tip of a magnetised guidewire in vivo aided by two permanent adjustable external magnets. METHODS: Crossing and fluoroscopy times of six operators were evaluated in five tortuous Perspex(R) phantom vessels in three consecutive attempts. Standard guidewire (SG) usage was unrestricted. Two 2nd generation magnetic guidewires (MG) were used. Failure was noted if the cross was unsuccessful within 5 min. RESULTS: The magnetic navigation was vastly superior to SG techniques with increasingly tortuous phantoms. It dramatically decreased both the crossing and fluoroscopy times with maximal reduction from 201.7 +/- 111 to 36.4 +/- 13 sec, P < 0.001 and 204.7 +/- 24 to 47.2 +/- 19 sec, P < 0.001, respectively. The MNS had a 98.8% procedural success rate compared to 68% with SG techniques. Moreover it considerably limited the amount of wire usage from 5.5 to 1.3. Operators with prior MG experience performed significantly better than those without, except in the simplest phantom where the difference was nonsignificant (33.8 +/- 13 sec vs. 41.7 +/- 17 sec, P = 0.2). CONCLUSION: MNS significantly reduces both the crossing and fluoroscopy times in tortuous coronary phantom models achieving excellent success rates with dramatic reductions in guidewire usage. Operators with prior MNS experience had an advantage over the inexperienced.     

Integration of dual source computed tomography With magnetic navigation system for percutaneous coronary intervention: A feasibility study

Objectives : To investigate the feasibility of integration of the dual source computed tomography (DSCT) and magnetic navigation system (MNS) to guide percutaneous coronary intervention (PCI). Background : MNS has proven to be feasible for yielding high rates of procedural success for PCI. DSCT coronary angiography (DSCT‐CA) may provide a roadmap of a target vessel and serve as a reference route for MNS. Combination of these two technologies might decrease the contrast use, fluoroscopy exposure, and be beneficial to the intervention of the totally occluded lesions. Methods : Twenty‐five patients with positive results of DSCT‐CA and indications for PCI were included. CT images were transferred to MNS, and target vessels were extracted and registered to X‐ray system as a roadmap. Results : DSCT‐CA and MNS‐assisted PCIs were successfully performed in 25 of the 26 target vessels (96.2%), with the mean guidewire crossing time of 100.0 (25–75% inter‐quartile ranges (IQR): 70.7–157.8) sec, mean total radiation dosage of 268.1 (IQR: 150.5–527.0) μGym², or 42.0 (IQR: 23.0–70.0) mGy, respectively. The contrast usage for guidewire positioning was 0 (IQR: 0–3.0) ml for the successfully crossed lesions. Both of the two totally occluded lesions in this study were successfully crossed with guidewires under the guidance of the DSCT‐CA derived roadmap. Conclusion : Integration of DSCT with MNS for PCI is feasible. This integration of advanced modalities might decrease contrast usage, lower fluoroscopy exposure for guidewire positioning, and might also play a role in totally occluded lesions. © 2011 Wiley Periodicals, Inc.     

Guidewire navigation in coronary artery stenoses using a novel magnetic navigation system: first clinical experience.

The objective of this study was to investigate the efficacy of guidewire navigation across coronary artery stenoses using magnetic navigation system (MNS) versus conventional navigation. The MNS is a novel option to facilitate access to target lesions, particularly in tortuous vessels. In an experimental study using a challenging vessel phantom, magnetic-navigated guidewire passage has been reported to reduce fluoroscopy and procedure time significantly. Both magnetic and manual guidewire navigation were attempted in 21 consecutive diseased coronary arteries. The study endpoint was defined as an intraluminal wire position distal to the stenosis. Procedural success was defined as successful guidewire passage without procedural events. Procedure time, amount of contrast, fluoroscopy time, and radiation dose/area product (DAP) were evaluated. There were no procedural events related to either guidewire. Although the lesions attempted had relatively simple and straightforward characteristics, significantly shorter procedure and fluoroscopy time were observed for manual guidewire navigation compared to MNS (median, 40 vs. 120 sec, P=0.001; 38 vs. 105 sec, P=0.001, respectively). Contrast amount and DAP were higher in MNS than in conventional method (median, 13 vs. 9 ml, P=0.018; 215 vs. 73 Gym2, P=0.002, respectively). The magnetic wire did not cross in two vessels. Guidewire navigation using MNS presented a novel, safe, and feasible approach to address coronary artery lesions. Clinical studies are needed to evaluate the potential benefit of the MNS in more complex coronary lesions and tortuous anatomy.     

Use of the Stereotaxis Niobe® magnetic navigation system for percutaneous coronary intervention: Results from 350 consecutive patients

Introduction : The Stereotaxis Niobe® magnetic navigation system (MNS; Stereotaxis, St. Louis, MO) facilitates precise vector based navigation of magnetically‐enabled guidewires for percutaneous coronary intervention (PCI) by using two permanent magnets located on opposite sides of the patient table to produce a controllable magnetic field. The objective of this study is to describe the results of a large patient series using this system, to compare the results with a historical control group, and to detail the MNS learning curve. Methods : We prospectively collected data on 439 lesions in 350 consecutive PCI patients using the MNS predominantly using the radial approach. All data were entered into a customized database to capture the key parameters and then compared with a previously collected stent registry from the same center. Results : In 410/439 lesions (93%) the wire crossed the lesion successfully using the MNS. Twenty‐five of the 35 failures were chronic total occlusions. No wire perforations or dissections occurred in this population. Lesion crossing time was 81 ± 168 sec (mean ± SD), and fluoroscopy time was 64 ± 123 sec. A clear learning curve was evident after the first 80 patients. Contrast use was reduced when compared with a historical control group. Procedural and fluoroscopy times were similar. Conclusions : Use of the MNS may enable the successful performance of more complex procedures in the cardiac catheterization laboratory with an improvement in time efficiency. © 2008 Wiley‐Liss, Inc.     

Initial clinical experience of remote magnetic navigation system for catheter mapping and ablation of supraventricular tachycardias

Background  A remote magnetic navigation system (MNS) has been developed for mapping and catheter ablation of cardiac arrhythmias. The present study evaluates the safety and feasibility of this system to perform radiofrequency (RF) ablation in patients with supraventricular tachycardias (SVT). Methods  A total of 32 patients (22 female; mean age 44 ± 16 years) with documented SVT underwent mapping and ablation using Helios II (a 4-mm-tip magnetic catheter), under the guidance of the MNS (Niobe II, Stereotaxis, Inc.). Results  Catheter ablation procedure with MNS was successful in 30/32 (94%) patients including all patients (27/27, 100%) with atrioventricular nodal reentrant tachycardia (AVNRT) and three of five patients (60%) with atrioventricular reentrant tachycardia (AVRT) without any complication. The procedural successful rate in patients with AVNRT was significantly higher than those in patients with AVRT (P < 0.001). Overall, the medium number of RF application using the MNS was 2 (mean 2.7 ± 1.6, range 1 to 7), and the medium numbers of RF for AVNRT and AVRT were 2 and 3, respectively. There was no significant difference in the mean procedural time between patients with AVNRT and AVRT (126.3 ± 38.6 vs. 138.0 ± 40.3 min, P = 0.54). However, the mean fluoroscopy time was significantly shorter in patients with AVNRT than those with AVRT (5.7 ± 3.0 vs. 16.5 ± 2.5 min, P < 0.001). Among those patients with AVNRT, the mean procedural time (139.3 ± 45.0 vs. 112.3 ± 24.9 min, P = 0.07) and fluoroscopic time (3.2 ± 1.0 vs. 8.0 ± 2.2 min, P < 0.001) were shorter for the later 13 patients than the first 14 patients, suggesting a learning curve in using the MNS for RF ablation. Conclusions  The Niobe MNS is a new technique that can allow safe and effective remote-controlled navigation and minimize the need for fluoroscopic guidance for ablation catheter of AVNRT. However, further improvement is required to achieve a higher successful rate for treatment of AVRT. Drs. Xu and Yang contributed equally to this work.     

Catheter ablation of ventricular tachycardias using remote magnetic navigation: a consecutive case-control study

Remote Magnetic Navigation for VT Ablation. Background: This study aimed to compare acute and late outcomes of VT ablation using the magnetic navigation system (MNS) to manual techniques (MAN) in patients with (SHD) and without (NSHD) structural heart disease. Methods: Ablation data of 113 consecutive patients (43 SHD, 70 NSHD) with ventricular tachycardia treated with catheter ablation at our center were analyzed. Success rate, complications, procedure, fluoroscopy, and ablation times, and recurrence rates were systematically recorded for all patients. Results: A total of 72 patients were included in the MNS group and 41 patients were included in the MAN group. Patient age, gender, and right ventricular and left ventricular VT were equally distributed. Acute success was achieved in 59 patients in the MNS group (82%) versus 27 (66%) patients in the MAN group (P = 0.046). Overall procedural time (177 ± 79 vs 232 ± 99 minutes, P < 0.01) and mean patient fluoroscopy time (27 ± 19 vs 56 ± 32 minutes, P < 0.001) were all significantly lower using MNS. In NSHD pts, higher acute success was achieved with MNS (83,7% vs 61.9%, P = 0.049), with shorter procedure times (151 ± 57 vs 210 ± 96, P = 0.011), whereas in SHD‐VT these were not significantly different. No major complications occurred in the MNS group (0%) versus 1 cardiac tamponade and 1 significantly damaged ICD lead in the MAN group (4.9%, NS). After follow‐up (20 ± 11 vs 20 ± 10 months, NS), VT recurred in 14 pts (23.7%) in the MNS group versus 12 pts (44.4%) in the MAN group (P = 0.047). Conclusions: The use of MNS offers advantages for ablation of NSHD‐VT, while it offers similar efficacy for SHD‐VT. ((J Cardiovasc Electrophysiol, Vol. 23, pp. 948‐954, September 2012)     

Coronary artery injection technique: A quantitative in vivo investigation using modern catheters

To date, there have been no quantitative in vivo assessments of contrast volumes and injection rates using modern high flow catheters during coronary angiography. Contrast volumes (n = 554), injection durations (n = 563), and injection rates (n = 498) were collected during 88 cardiac catheterizations. With increasing cathetersize (6, 7, and 8 French), injection volume increased (P < 0.0001), duration decreased (P < 0.0001), and rate increased (P < 0.0001). Compared with injections into the right coronary artery, left coronary artery injections were larger (7.1 ± 0.1 cc vs. 4.8 ± 0.1 cc, p < 0.0001), longer (3.6 ± 0.05 sec vs 3.0 ± 0.07 sec, P < 0.0001) and faster (2.1 ± 0.04 cc/sec vs. 1.7 ± 0.06 cc/sec, P < 0.0001). Patients with a significant stenosis in the left main or proximal right coronary artery received less contrast (P < 0.0001) more slowly (P < 0.0001) over a similar duration of injection (P = NS). When collaterals arose from the injected artery, angiographers injected more contrast (P < 0.001) over a longer period (P < 0.0001) more slowly (P < 0.0001). Catheter size and the injected vessel's location and anatomy significantly affect coronary catheterization injection technique. Cathet. Cardiovasc. Diagn. 44:34-39, 1998. © 1998 Wiley-Liss, Inc.     

Initial experience with a magnetic navigation system for invasive treatment in patients with non-ST-segment elevation acute coronary syndromes

Background: Magnetic navigation system (MNS) assisted percutaneous coronary intervention (MPCI) has been demonstrated an advantage over conventional PCI (CPCI) in complex lesions and tortuous vessels. However, the benefits of MNS in clinical unstable and vulnerable lesions were little studied. The aim of this study is to evaluate the feasibility and benefits of MPCI versus CPCI in patients with non‐ST‐segment elevation acute coronary syndromes (NSTE‐ACS). Methods: Thirty‐seven consecutive patients with NSTE‐ACS undergoing MPCI were compared with 37 matched CPCI patients selected from the same concurrent database. Time to cross lesion, fluoroscopy time, and contrast usage to cross lesion were used as primary end‐points. Results: Of the 37 culprit lesions in MPCI, 36 were crossed successfully giving a success rate of 97.3%. The procedure and the fluoroscopy time to cross the lesion were similar between the magnetic and conventional PCI groups (82.0 ± 67.9 seconds vs. 85.8 ± 59.2 seconds, P = 0.692, and 62.6 ± 57.6 seconds vs. 65.4 ± 49.5 seconds, P = 0.738, respectively). In Type A/B1 lesions, there seemed no difference in contrast use (2.7 ± 0.7 mL vs. 3.3 ± 0.9 mL, P = 0.284). But as lesion complexity increased from type B2 to C, significantly less contrast was needed in type B2 (5.1 ± 2.6 mL vs. 7.9 ± 4.0 mL, P = 0.019) and type C (9.8 ± 5.7 mL vs. 14.7 ± 7.4 mL, P = 0.030). No major adverse cardiac events were observed in either the MPCI or CPCI group. Conclusions: MNS assisted technique appears to be feasible and effective in NSTE‐ACS patients with more complex lesions; however, it probably offers little benefit in simple lesions like ACC/AHA type A/B1. (J Interven Cardiol 2011;24:549–554)     

The ACIST power injection system reduces the amount of contrast media delivered to the patient,as well as fluoroscopy time,during diagnostic and interventional cardiac procedures

The ACIST injection system is an automatic power injection device that allows for online control of injection rate and volume of contrast. Limited data is available whether this technology allows reducing use of contrast and fluoroscopy time. Accordingly, we compared the use of this system to manual injection among 450 consecutive patients who underwent diagnostic coronary angiography and/or angioplasty who were randomly assigned to either manual contrast injection (control; n = 198) or to the ACIST system (study group; n = 252). The amount of contrast, fluoroscopy and total procedural times were recorded for each patient. In the diagnostic group, the mean total amount of contrast (including wasted) was reduced by 63% when the ACIST was used compared to control (100±42?ml versus 163±56?ml; P<0.001, respectively). When only the net amount of contrast delivered to the patient was considered, the differences were smaller (20%, P = 0.004). During angioplasty, the amount of contrast was also lower in the ACIST group (206±65 versus 230±69, P = 0.008), whereas no difference were noted in net amount of contrast. Fluoroscopy time was significantly shorter in the ACIST group compared to control both during diagnostic catheterization (4.7±3.5?min versus 6.3±5.5?min, respectively; P = 0.014), and angioplasty (16.7±9.1?min versus 19.6±12.4?min, respectively; P = 0.05). Routine utilization of the ACIST system during diagnostic and interventional procedure significantly reduced the total amount of contrast media used and fluoroscopy time.     

Initial clinical experience with cardiac resynchronization therapy utilizing a magnetic navigation system

Introduction: The placement of left ventricular (LV) leads during cardiac resynchronization therapy (CRT) involves many technical difficulties. These difficulties increase procedural times and decrease procedural success rates. Methods and Results: A total of 50 patients with severe cardiomyopathy (mean LV ejection fraction was 21 ± 6%) and a wide QRS underwent CRT implantation. Magnetic navigation (Stereotaxis, Inc.) was used to position a magnet‐tipped 0.014″ guidewire (Cronus? guidewire) within the coronary sinus (CS) vasculature. LV leads were placed in a lateral CS branch, either using a standard CS delivery sheath or using a “bare‐wire” approach without a CS delivery sheath. The mean total procedure time was 98.1 ± 29.1 minutes with a mean fluoroscopy time of 22.7 ± 15.1 minutes. The mean LV lead positioning time was 10.4 ± 7.6 minutes. The use of a delivery sheath was associated with longer procedure times 98 ± 32 minutes vs 80 ± 18 minutes (P = 0.029), fluoroscopy times 23 ± 15 minutes vs 13 ± 4 minutes (P = 0.0007) and LV lead positioning times 10 ± 6 minutes vs 4 ± 2 minutes (P = 0.015) when compared to a “bare‐wire” approach. When compared with 52 nonmagnetic‐assisted control CRT cases, magnetic navigation reduced total LV lead positioning times (10.4 ± 7.6 minutes vs 18.6 ± 18.9 minutes; P = 0.005). If more than one CS branch vessel was tested, magnetic navigation was associated with significantly shorter times for LV lead placement (16.2 ± 7.7 minutes vs 36.4 ± 23.4 minutes; P = 0.004). Conclusions: Magnetic navigation is a safe, feasible, and efficient tool for lateral LV lead placement during CRT. Magnetic navigation during CRT allows for control of the tip direction of the Cronus? 0.014″ guidewire using either a standard CS delivery sheath or “bare‐wire” approach. Although there are some important limitations to the 0.014″ Cronus? magnetic navigation can decrease LV lead placement times compared with nonmagnetic‐assisted control CRT cases, particularly if multiple CS branches are to be tested.     

Intracardiac Echocardiography Improves Procedural Efficiency During Cryoballoon Ablation for Atrial Fibrillation: A Pilot Study

Intracardiac Echocardiography Guided Cryoballoon Ablation. Background: Cryoballoon ablation is increasingly used for pulmonary vein isolation (PVI) in patients with atrial fibrillation (AF). This new technique aims to perform PVI safer and faster. However, procedure and fluoroscopy times were similar to conventional RF approaches. We compared ICE plus fluoroscopy versus fluoroscopy alone for anatomical guidance of PVI. Methods: Forty‐three consecutive patients with paroxysmal AF were randomly assigned to ICE plus fluoroscopy (n = 22) versus fluoroscopy alone (n = 21) for guidance of cryoballoon PVI. A “single big balloon” procedure using a 28 mm cryoballoon was performed. The optimal ICE‐guided position of the cryoballoon was assessed by full ostial occlusion and loss of Doppler coded reflow to the left atrium (LA). Any further freezes were ICE‐guided only without use of fluoroscopy or contrast media injection. Results: A total of 171 pulmonary veins could be visualized with ICE. 80% of ICE‐guided freezes were performed with excellent ICE quality. Acute procedural success and AF recurrence rate at 6 months were similar in both groups (AF recurrence: ICE‐guided = 27% vs Fluoroscopy = 33%; P = ns). Patients without ICE guidance had significantly longer procedure (143 ± 27 minutes vs 130 ± 19 minutes; P = 0.05) and fluoroscopy times (42 ± 13 minutes vs 26 ± 10, P = 0.01). The total amount of contrast used during the procedure was significantly lower in patients with ICE guidance (88 ± 31 mL vs 169 ± 38 mL, P < 0.001). Conclusion: Additional ICE guidance appears to be associated with lower fluoroscopy, contrast, and procedure times, with similar efficacy rates. Specifically, ICE allows for better identification of the PV LA junction and more precise anatomically guided cryoballoon ablations. (J Cardiovasc Electrophysiol, Vol. 21, pp. 1202‐1207, November 2010)     

Single-stage balloon valvuloplasty for critical pulmonary valve stenosis in the neonate

Balloon valvuloplasty (BV) in neonates with critical pulmonary valve stenosis (CPVS) is limited by technical considerations, mainly the difficulty of traversing the stenotic valve. To simplify the procedure we used a 4F Cobra Type I catheter to cross the pulmonary valve (PV) without the aid of a guidewire, and performed single-stage BV, using low-profile balloons, in 12 neonates with CPVS. Procedure and total fluoroscopy times were 69 ± 33 min (42–125 min) and 34 ± 19 min (20–58 min), respectively. Following BV, right ventricular systolic pressure (RVSP) decreased from 102 ± 17 mm Hg to 56 ± 15 mm Hg (p < 0.001); and the ratio of RVSP to aortic systolic pressure decreased from 1.39 ± 0.22 to 0.73 ± 0.21 (p < 0.001). No significant complications were observed. BV failed in two patients, who subsequently had surgery. At follow-up (a mean of 19 months), Doppler gradient was 19 ± 12 mm Hg (0–50 mm Hg). BV was repeated in one patient. We conclude that in neonates with CPVS, the use of the 4F Cobra type I catheter facilitates crossing of the PV and allows performance of BV in a single stage; this enhances safety and time-efficiency, and shortens exposure to radiation. Cathet. Cardiovasc. Diagn. 40:322–325, 1997. © 1997 Wiley-Liss, Inc.     

Assessment of Left Ventricular Hemodynamics and Function of Patients with Uremia by Vortex Formation Using Vector Flow Mapping

A novel echocardiographic method, vector flow mapping (VFM), acquires velocity vector from color Doppler velocity data. The purpose of this study was to evaluate whether VFM could provide useful information on intracardiac flow and helpful to evaluate left ventricular (LV) function. Thirty‐eight patients with uremia undergoing hemodialysis and 30 healthy volunteers were enrolled. The maximum vector velocity, maximum diameter and duration of the intracardiac vortex were measured using VFM software during systole and diastole. The maximum vector velocity of the vortex and the peak velocities at the basal septum and lateral mitral annulus measured by tissue Doppler imaging (TDI) were correlated. The maximum diameter and duration of vortex formation were significantly higher in uremic patients compared with the control group during the ejection phase (40.6 ± 7.9 cm/sec vs. 28.1 ± 3.9 cm/sec; 297.1 ± 22.1 msec vs. 145.4 ± 19.3 msec, all P < 0.001). The maximal diameters of the vortex were higher in uremic patients compared with the control group during diastole (25.6 ± 3.4 mm vs. 16.4 ± 2.1 mm; 34.3 ± 3.1 mm vs. 26.8 ± 3.9 mm; 37.5 ± 2.4 mm vs. 20.9 ± 2.1 mm; all P < 0.001). The maximum vector velocities were lower in mid‐diastole and late diastole (23.6 ± 2.3 cm/sec vs. 45.2 ± 3.7 cm/sec; 31.9 ± 2.9 cm/sec vs. 54.7 ± 3.2 cm/sec, all P < 0.001). There was a correlation between the maximum vector velocity of the vortex in mid‐diastole and E'/A' at the septum and lateral mitral annulus (r = 0.70, r = 0.76, P < 0.001). Vortex can be utilized to provide intracardiac dynamic information using VFM and it may be a good supplement for evaluating LV function.     

Mini-STAR as bail-out strategy for percutaneous coronary intervention of chronic total occlusion

Background: Although the advancement of the equipment and the presence of innovative techniques, percutaneous coronary intervention (PCI) for chronic total occlusion (CTO) continues to be affected by lower procedural success in comparison with non occluded vessel PCI. Objective: We describe a new technique for the treatment of coronary CTO which utilizes a new generation of polymeric wires. Methods and Result: From March 2009 to June 2010 different strategies were adopted as “bail out” after an initial attempt failed in 117 consecutive CTO lesions. Among these, conventional strategies (CS) such as parallel wire, sub‐intimal tracking and re‐entry (STAR), microchannel technique, intracoronary ultrasound guided revascularization and anchor balloon, were used in 75 cases (64.1%), while in the remaining a new technique, the “mini‐STAR,” was used (39.9%). Although no substantial differences were observed regarding the distribution of clinical features and angiographic lesions characteristics between the populations, mini‐STAR was able to achieve a higher rate of procedural success in comparison with other CS (97.6% vs. 52%, P < 0.001) with lower contrast agent use (442 ± 259 cm³ vs. 561 ± 243 cm³, P = 0.01) and shorter procedural and fluoroscopy times (122 ± 61 vs. 157 ± 74 min, P = 0.009 and 60 ± 31 min vs. 75 ± 38 min, P = 0.03, respectively). No differences were observed in term of peri‐procedural complications such as procedural myocardial infarction, coronary perforations, and contrast‐induced nephropathy between mini‐STAR and CS. Conclusion: The mini‐STAR technique is a promising strategy for the treatment of CTO lesions, achieving a high procedural success rate and low occurrence of procedural adverse events. © 2011 Wiley Periodicals, Inc     

Traditional antegrade approach versus combined antegrade and retrograde approach in the percutaneous treatment of coronary chronic total occlusions

Objectives : The goal of this study was to compare the antegrade‐approach and bilateral‐approach strategies for chronic total occlusion (CTO). Background: The retrograde approach has been reported for difficult CTO lesions. Methods : This study assessed 96 consecutive patients with 119 CTO lesions. The lesions were treated with either an antegrade approach (A group) or a combined bilateral antegrade and retrograde approach (B group). The specific intervention techniques, in‐hospital success rate, and major adverse cardiac and cerebrovascular events (MACCE) were compared. Results : Lesions with well‐developed septal collaterals with nontortuous microchannels were preferentially chosen for the B group versus A group (P < 0.001 and 0.008, respectively). Compared with the A group, there were more CTO lesions located in the right coronary artery in the B group (P < 0.001). In the B group, the CTO lesions had a longer length and needed stiffer wires for crossing than in the A group (P = 0.001 and 0.046, respectively). The technical success rate was 94% and 86% for the A group and the B group, respectively (P = 0.127). In‐hospital complications were not different between the two groups. The B group needed a higher radiation exposure dose and a greater exposure time than the A group (P < 0.001). In the B group, use of the retrograde method significantly increased the final success rate. Conclusions: These results suggest that all CTO lesions should first be managed with an antegrade approach. When there is difficulty crossing the lesion, switching to a bilateral approach is an option for lesions with well‐developed collaterals. © 2009 Wiley‐Liss, Inc.     

Coronary blood flow velocities during rotational atherectomy

This study was designed to evaluate the alterations in doppler derived coronary blood flow velocities and flow reserve following rotational ablation. Changes in doppler derived coronary blood flow velocity variables have been valuable in assessing the physiological outcome following coronary balloon angioplasty. Rotational ablation's mechanism of plaque removal could alter distal vascular bed characteristics, and, as a result, intracoronary blood flow velocities and the coronary flow reserve. A 12-MHz doppler guidewire recorded intracoronary phasic velocities and coronary flow reserve (as assessed by the hyperemic response to adenosine [12–18 mcg intracoronary]) in 28 patients, before and after rotational ablation of 30 lesions. Adjunctive balloon angioplasty was performed in 27 of 28 patients (96%). Rotational ablation and adjunctive balloon angioplasty successfully reduced the lesion diameter (87 ± 9% to 14 ± 11%; P < 0.001). A significant increase in the mean distal average peak velocity (25 ± 13 cm/sec, before; 47 ± 22 cm/sec, after; P < 0.001), and decrease in the proximal to distal average peak velocity ratio, (2.1 ± 1.3; to 1.2 ± 0.4; P = 0.002) was recorded. The mean distal diastolic to systolic velocity ratio (before, 1.4 ± 0.7; after, 1.6 ± 0.8; P = 0.44) and the coronary flow reserve (before, 1.6 ± 0.6; after, 1.5 ± 0.5; P = 0.34) did not increase despite increases in distal velocities, following successful intervention. Doppler derived distal coronary blood flow velocities increased following rotational ablation and adjunctive balloon angioplasty, with resolution of transstenotic velocity gradient. Changes in distal phasic velocity pattern and coronary flow reserve, immediately after the intervention, were not useful in the assessment of the functional outcome and may be related to abnormalities in distal vascular bed vasoreactivity produced by rotational ablation. Cathet. Cardiovasc. Diagn. 41:152–156, 1997. © 1997 Wiley-Liss, Inc.     

Does coronary flow reserve assessed by blood flow velocity analysis reflect absolute coronary flow reserve?

Doppler guidewire enables us to measure phasic coronary velocity and has been used for the measurement of coronary flow reserve (CFR). Although CFR is usually calculated by the quotient of peak flow velocity during papaverine infusion and flow velocity at rest, this assumption is true only if conduit vessel size is constant. To determine the accuracy of measurement of CFR using average peak velocity (APV) with Doppler guidewire, we investigated the influence of intracoronary papaverine on coronary flow velocity and coronary arterial diameter (CAD) and examined the correlation between CFR derived using APV and that derived using coronary blood flow (CBF) in 26 patients with normal coronary arteries. We measured phasic coronary flow velocity, and performed quantitative coronary angiography in the proximal left coronary artery at control and during 10 mg of intracoronary papaverine. Compared to control value, papaverine induced a significant increase in APV (% increase: 182 ± 101%; P<0.001). Papaverine also significantly increased CAD (16 ± 10%; P<0.001). Thus, CFR derived from APV was significantly lower than that derived from CBF (2.8 ± 1.0 vs. 4.0 ± 1.5, P<0.001). Although there was a significantly strong positive correlation between these two methods (R² = 0.83, P<0.001), there was also considerable variability with regard to predicting one variable from the other. These results suggest the importance of standardizing the conditions in which coronary flow velocity is measured with regard to either controlling or measuring changes in epicardial coronary arterial diameter during changes in distal resistance vessel tone. © 1996 Wiley-Liss, Inc.     

ACC/AHA classification of coronary lesions reflects medical resource use in current percutaneous coronary interventions

Objectives : The purpose of this study was to investigate the association between ACC/AHA type classification of coronary lesions and medical resource utilization. Background : It is not known whether the classification of coronary lesions by the ACC/AHA system reflects the consumption of medical resources in current percutaneous coronary interventions (PCI). Methods : We identified coronary artery lesions treated with PCI from our PCI database between January 1, 2009 and December 31, 2009. Lesions were classified into type A, type B1, type B2, and type C according to the ACC/AHA definition. Total PCI cost, total contrast volume, and total fluoroscopy time were compared among the groups. Results : A total of 447 lesions were analyzed. The number of type A, type B1, type B2, and type C lesion were 75 (16.8%), 98 (21.9%), 145 (32.4%), and 129 (28.9%), respectively. Total PCI cost for type A, type B1, type B2, and type C lesions were $7,262 ± 1,397, $8,126 ± 1,891, $9,126 ± 3,128, and $13,243 ± 4,678, respectively (P < 0.0001). Total contrast volume and fluoroscopy time were also stratified according to the order of type A, type B1, type B2, and type C lesions (P < 0.0001 for total contrast volume; P < 0.0001 for total fluoroscopy time). Conclusions : Total PCI cost, total contrast volume, and total fluoroscopy time were clearly stratified according to the order of type A, type B1, type B2, and type C lesions. Lesion classification by the ACC/AHA system reflects medical resource use in current PCI. © 2011 Wiley Periodicals, Inc.     

Alveolar and bronchial nitric oxide output in healthy children

Exhaled nitric oxide (NO) concentration is a marker of pulmonary inflammation. It is usually measured at a single exhalation flow rate. However, measuring exhaled NO at multiple flow rates allows assessment of the flow‐independent NO parameters: alveolar NO concentration, bronchial NO flux, bronchial wall NO concentration, and bronchial diffusing capacity of NO. Our aim was to determine the flow‐independent NO parameters in healthy schoolchildren and to compare two different mathematical approaches. Exhaled NO was measured at four flow rates (10, 50, 100, and 200 ml/sec) in 253 schoolchildren (7–13 years old). Flow‐independent NO parameters were calculated with linear method (flows ≥50 ml/sec) and non‐linear method (all flows). Sixty‐six children (32 boys and 34 girls) with normal spirometry and no history or present symptoms of asthma, allergy, atopy or other diseases were included in the analysis. Median bronchial NO flux was 0.4 nl/sec (mean ± SD: 0.5 ± 0.3 nl/sec) and median alveolar NO concentration was 1.9 ppb (2.0 ± 0.8 ppb) with the linear method. Bronchial NO flux correlated positively with height (r = 0.423; P < 0.001), FEV₁ (r = 0.358; P = 0.003), and FVC (r = 0.359; P = 0.003). With the non‐linear method, median bronchial wall NO concentration was 49.6 ppb (68.0 ± 53.3 ppb) and bronchial diffusing capacity of NO was 10.0 pl/sec/ppb (11.8 ± 7.5 pl/sec/ppb). The non‐linear method gave lower alveolar NO concentration (1.4 [1.5 ± 0.7] ppb, P < 0.001) and higher bronchial NO flux (0.5 [0.6 ± 0.3] nl/sec, P < 0.001) than the linear method, but the results were highly correlated between the two methods (r = 0.854 and r = 0.971, P < 0.001). In conclusion, the multiple flow rate method is feasible in children but different mathematical methods give slightly different results. Reference values in healthy children are of value when applying bronchial and alveolar NO parameters in the diagnostics and follow‐up of inflammatory lung diseases. Pediatr. Pulmonol. 2008; 43:1242–1248. © 2008 Wiley‐Liss, Inc.     

Use of intra-aortic nitroglycerin in the cardiac catheterization laboratory

The purpose of this study was to determine whether nitroglycerin (NTG) injected into the ascending aorta or left ventricle would safely and effectively lower blood pressure in hypertensive patients undergoing cardiac catheterization. Fifty bolus injections of 297 ± 67 μg (mean ± SD) NTG were given to patients with a systolic blood pressure (SBP) of ?140 mm Hg (mean SBP 188 ± 20.1 mm Hg). An average drop in systolic blood pressure of 36 ± 16 mmHg (P < 0.001), diastolic blood pressure of 19 ± 7 mm Hg (P < 0.001), and left ventricular end-diastolic pressure of 4.7 ± 4 mm Hg (P = 0.001) was well tolerated in each patient. The mean time to response was 11 ± 3 sec. Intra-aortic injection of NTG is a safe and effective means to treat hypertensive patients in the cardiac catheterization laboratory. © 1995 Wiley-Liss, Inc.