William Ng

Initial experience and safety in the treatment of chronic total coronary occlusions with a new optical coherent reflectometry-guided radiofrequency ablation guidewire

The Safe-Cross wire system, which has optical coherence reflectometry technology for navigating and radiofrequency energy provided at its tip for crossing chronic total occlusions (CTOs), provides a promising means to treat hard, organized CTOs. Using this system, we report on a 60% success rate in patients who had long-standing coronary CTOs that had > or =1 failed attempt using conventional percutaneous coronary intervention.

Concomitant coronary and subclavian steal caused by ipsilateral subclavian artery stenosis and arteriovenous fistula in a hemodialysis patient.

Patients with chronic renal failure, because of concomitant conventional cardiovascular and uremia‐associated risk factors, are at risk of developing diffuse and accelerated atherosclerosis involving both the coronary and peripheral territories. We report an end‐stage renal failure patient with a history of coronary artery bypass surgery who developed both angina and dizziness during hemodialysis via a left forearm arteriovenous fistula. Magnetic resonance imaging diagnosed the presence of significant subclavian artery stenosis. The patient then underwent successful percutaneous stenting of the left subclavian artery. His angina and dizziness symptoms resolved subsequently. Catheter Cardiovasc Interv 2004;62:244–248.

Recanalization of chronic and long occlusive in-stent restenosis using optical coherence reflectometry-guided radiofrequency ablation guidewire

Chronic total occlusions remain a challenge to interventionalists due to failure of crossing or perforation by strong wires. We describe the use of a system using optical coherence reflectometry for navigation and radiofrequency ablation to enable wire passage through occlusions that could not be crossed by conventional guidewires. Cathet Cardiovasc Intervent 2003;59:223–229.

Safety and feasibility of the use of a distal filter protection device in percutaneous revascularization of small coronary arteries

The FilterWire EX is one of the filter protection devices developed as alternatives to balloon occlusion system for percutaneous coronary intervention. Its use has been recommended in vessels between 3.5 and 5.5 mm in diameter and no data are available on its use in smaller vessels. We evaluated the safety and feasibility of using FilterWire EX in native coronary arteries smaller than 3.5 mm. We successfully deployed and retrieved the FilterWire EX in 49 coronary arteries with a mean vessel diameter of 2.62 ± 0.45 mm at device deployment. Reversible vasospasm was observed in 24 (50%) vessels, coronary flow was temporarily reduced in 22 (44.9%), and distal embolization was noted in 2 (4%). There was no vessel dissection induced by the device. These data suggest that it is safe and feasible to use the FilterWire EX in small coronary arteries. Catheter Cardiovasc Interv 2004;61:360–363.

Cardiac arrhythmias as presenting symptoms in patients with limb-girdle muscular dystrophy

Clinically manifest muscular dystrophy is often accompanied by functional and anatomic derangements in the myocardium which often have prognostic significance. We describe two young patients who had unrecognized limb-girdle muscular dystrophy who presented with cardiac arrhythmia. One developed dilated cardiomyopathy complicated by ventricular tachyarrhythmia. The other patient had atrial paralysis requiring permanent pacing. It is important to consider the possibility of underlying muscular dystrophy in patients who present with cardiac arrhythmia without an obvious cause.

Percutaneous recanalization of chronic subclavian artery occlusion using optical coherence reflectometry-guided radiofrequency ablation guidewire

Subclavian artery lesion that is associated with low complication rate could be treated by percutaneous intervention effectively. However, the success of endovascular therapy for occlusive lesion may be limited by failure to cross with a guidewire. We describe the use of a system using optical coherence reflectometry for navigation and radiofrequency ablation to enable wire passage through subclavian artery occlusion that could not be crossed by conventional guidewires. Catheter Cardiovasc Interv 2003;60:558–561.

Double-Stenting of the Left Main Coronary Artery lesions: Safety, Clinical Outcome and Long Term Follow-up

This study aimed to assess the safety & medium/long-term outcome of using double-stenting strategy on left main (LM) stem for the treatment of significant suboptimal angiographic result after initial left main coronary artery (LMCA) stent implantation. Between August 2005 & June 2010, patients undergoing PCI with doublestenting of LMCA lesions comprised the study cohort. Baseline characteristics, EuroSCORE (I), lesions & stent characteristics and outcomes were analyzed. Thirty-eight patients were included in the study. Sixty-three percent were male, mean age of 73 years old, 37% were diabetic & 74% had unprotected LMCA stenting. Majority presented with acute coronary syndrome (57%) in which 7 (18%) had STEMI. They represented a high risk cohort with high EuroSCORE (l) (logistic 17.7 ± 19.1%, additive 8.2 ± 4.7). In addition, 32 (84%) patients had multi-vessels disease. Estimated left ventricular ejection fraction in the series was 54 ± 13%. Drug eluting stents were placed in all cases as the first stent (mean size 3.55 ± 0.28mm), 34 (89%) patients had bare metal stent as the second stent (mean size 4.15 ± 0.43mm). All stents were placed successfully. There was no in-hospital death. At one year, for those who survived, no patient required repeat PCI to LMCA lesion and non-target lesion revascularization was 16%. One-year survival was 87% & 82% by the end of second year. In conclusion, favorable outcomes were seen in this unselected series of patients undergoing double-stenting of LM stem lesions. The technique is safe and feasible, provides another option for treatment of severe LMCA disease with suboptimal initial stenting result.