Radial intracardiac echocardiography adds significant anatomic correlation during invasive EP studies. In particular, coronary sinus (CS) anatomy can be evaluated during CS access or ablation of the slow AV nodal pathway during AVNRT ablations.  A steerable sheath (Agilis, St. Jude Medical) flushing with saline holds a 9MHz radial ICE catheter (UltraICE, Boston Scientific Corporation) and is positioned along the inferoseptal aspect of the tricuspid annulus.

Radial ICE CS Os Anatomy Final

The left image shows the posterior aspect of the CS os and you can often visualize the right coronary artery (RCA) in this view. One can see a thickened roof of CS (or often a prominent Eustachian ridge).  As the steerable sheath holding the ICE probe is advanced toward the right ventricle (RV), the main CS is brought into view as seen in the middle image.  As you move more ventricular, the septal insertion of the tricuspid valve leaflet is brought into view.  Finally, the right image depicts the radial ICE view when the anterior aspect of the CS os is brought into view as the probe is advanced even closer to the RV.  This is where the traditional position of the slow AVN pathway is found – the slow AV node pathway is generally located at the anterior edge of the CS os near the septal insertion of the tricuspid leaflet.

A nice anatomic study from Choure et al (“In Vivo Analysis of the Anatomical Relationship of Coronary Sinus to Mitral Annulus and Left Circumflex Coronary Artery Using Cardiac Multidetector Computed Tomography: Implications for Percutaneous Coronary Sinus Mitral Annuloplasty,” JACC, Vol. 48, No. 10, 2006) shows some detailed CT imaging of the relation between the coronary arteries and coronary sinus.  The following image (taken from Choure et al) gives a nice visualization of the CS os and its relation to the RCA.  One can see the circumflex crossing the mid-distal CS.  They found the circumflex artery crossed the CS at a variable distance from the CS os (ranging 37 to 123 mm).

RCA and Circ Relation to CS on CT

For more information about the use of radial ICE during EP studies:

Radial Intracardiac Echo Guided Ablation of AVNRT

Radial Intracardiac Echocardiography Guidance in the Electrophysiology Lab

Radial Intracardiac Echo (ICE) Guided Atrial Fibrillation Ablation

Perhaps we should be using atrial fibrillation (AF) as a marker for an at-risk population rather than a target for ablation? Ablations for atrial fibrillation (AF) have grown exponentially in the last few years as the technology has become widely available and catheter technology has evolved. Indeed, approximately 75000 AF ablations are performed per year at an estimated total cost of just over $1billion. AF catheter ablation is useful for symptomatic paroxysmal AF refractory or intolerant to at least one Vaughan Williams class I or III anti-arrhythmic medication when a rhythm-control strategy is desired. [1] AF ablations are justified based upon a vague definition of what constitutes “symptoms” and no concrete guidance on what defines an adequate attempt at anti-arrhythmic drug therapy. There are a few caveats to proceeding with an AF ablation [1]:


  1. Before consideration of AF catheter ablation, assessment of the procedural risks and outcomes relevant to the individual patient is recommended.
  2. Before initiating anti-arrhythmic drug therapy, treatment of precipitating or reversible causes of AF is recommended.


Procedural Risks and Outcomes of Ablation: When discussing the “risks, benefits, and alternatives” of any treatment recommendation, it is important to recognize inherent biases in this discussion. A recent study in JAMA [2] highlighted the worrisome issue that clinicians rarely had accurate expectations of benefits or harms of a wide variety of clinical therapies. Clinicians more often underestimated rather than overestimated harms and overestimated rather than underestimated benefits. Are the vast majority of AF ablation candidates counseled on the 4.5-12% rate of major complications [3,4,5] stemming from these procedures? This level of major complications rivals that stemming from CABG in many areas of the United States. Clearly, procedural risks of this magnitude suggest that, for persons with minimally symptomatic AF, the risk of ablation may outweigh the benefits. If only there were means by which to noninvasively reduce the burden of atrial fibrillation while we address overall population health…


Reversible Causes of Atrial Fibrillation: The ACC Guidelines state “Before initiating antiarrhythmic drug therapy, treatment of precipitating or reversible causes of AF is recommended.” Clinical risk factors for AF include: Hyperthyroidism

Increasing age, Hypertension, Diabetes mellitus, Myocardial Infarction, Valvular Heart Disease, Heart Failure, Obesity, Obstructive Sleep Apnea, Smoking, Lack of Exercise, and Alcohol Use.  I worry a generation of electrophysiologists are missing an opportunity to profoundly impact population health by performing ablations on patients with multiple, incompletely treated systemic diseases driving their arrhythmic burden. AF ablation in these patients may be tantamount to tacit approval we have done what we can for the patient and ablative therapy is the end rather than the beginning of their atrial fibrillation management.


Diet and Lifestyle: Smoking is associated with more than a two-fold increased risk of AF. In addition, a trend toward a lower incidence of AF appeared among smokers who quit compared to continued smokers. [6] In healthy women, BMI was associated with short- and long-term increases in AF risk, accounting for a large proportion of incident AF independent of traditional risk factors. [7] Among elderly adults, consumption of tuna or other broiled or baked fish, but not fried fish or fish sandwiches, is associated with lower incidence of AF. [8] Consumption of alcohol is associated with an increased risk of atrial fibrillation or flutter in men (but not women). [9]


Blood Pressure and Lipid Control: HTN doubles the risk for AF and accounts for more AF than any other risk factor. Antihypertensives reduce the risk for AF mainly by BP lowering and there is some evidence these drugs may reduce AF via other means as well. Both ACEIs and ARBs appear to be effective in the prevention of AF. This benefit appears to be limited to patients with systolic left ventricular dysfunction or LV hypertrophy. [10] The use of statins in patients with lone AF was associated with a significant decrease in the risk of arrhythmia recurrence after successful cardioversion. [11]


Obstructive Sleep Apnea: Obstructive sleep apnea is associated with an increased risk of AF after undergoing AF ablation. [12] Treatment of OSA with continuous positive airway pressure reduces the risk of recurrent AF after catheter ablation. [13] Obesity is one of the strongest OSA risk factors and has become an epidemic. [14]


There is a disorder which, when effectively treated, may result in the primary and secondary prevention of AF. Indeed, obesity is a major influence on the development and progression of cardiovascular disease and effects physical/social functioning as well as quality of life. [15]


Obesity and Atrial Fibrillation: Obesity has become an epidemic and is a major risk factor for cardiovascular diseases as well as quality of life. There is extensive data indicating that weight loss can reverse the deleterious effects of obesity and are further evidence of the causal link between obesity and disease. [15] Long-term sustained weight loss is associated with significant reduction of AF burden and maintenance of sinus rhythm. [16] Indeed, Pathak et al found that this effect persisted in patients with and without antiarrhythmic drugs or ablations. Even more significant, Jamaly et al reported the effects weight loss had on primary prevention of AF. They found the risk of AF was reduced by 29% in obese patients who underwent bariatric surgery, despite a less favorable cardiovascular risk factor profile at baseline. Weight loss has demonstrated success in both primary and secondary prevention of AF.



Summary: The current AF ablation recommendations (that have led to upwards of 75000 AF ablations yearly and cost of over $1billion [18]) are based upon studies that included a few hundred patients carefully enrolled that would have excluded many current AF ablation candidates based upon age and/or comorbidities. AF clinics are an opportunity to address the population health issue and provide care for the aforementioned chronic care issues however, I worry many of these AF clinics may simply be a means to enlarge the pipeline towards AF ablation referrals. What if we took a step back from AF ablation and focused our efforts on a patient-centered approach to AF using it as a population health outcomes measure and work on addressing the non-communicable diseases such as HTN, obesity, tobacco abuse, and inactivity? This may be a good mistake to make (in terms of overall population health) if I have undervalued the role of AF ablation.




  1. January CT et al, “2014 AHA/ACC/HRS Guideline for the Management of Patients With Atrial Fibrillation: A Report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines and the Heart Rhythm Society,” JACC, Vol. 64, No. 21 (2014) e1-e76.
  2. Hoffman TC and Del Mar C, “Clinicians’ Expectations of the Benefits and Harms of Treatments, Screening, and Tests A Systematic Review”, JAMA, January 9, 2017.
  3. Cappato R et al, “Updated Worldwide Survey on the Methods, “Efficacy, and Safety of Catheter Ablation for Human Atrial Fibrillation,” Circ Arrhythm Electrophysiol, V. 3 (2010), pp. 32-38.
  4. Packer et al, “Cryoballoon ablation of pulmonary veins for paroxysmal atrial fibrillation: first results of the North American Arctic Front (STOP AF) pivotal trial,” JACC 2013 Apr 23;61(16):1713-23.
  5. Kuck et al, “Cryoballoon or Radiofrequency Ablation for Paroxysmal Atrial Fibrillation,” NEJM, 2016; 374:2235-2245.
  6. Chamberlain AM et al, “Smoking and incidence of atrial fibrillation: results from the Atherosclerosis Risk in Communities (ARIC) study,” Heart Rhythm, V. 8, No. 8 (Aug 2011), pp. 1160-6.
  7. Tedrow UB et al, “The Long- and Short-Term Impact of Elevated Body Mass Index on the Risk of New Atrial Fibrillation: The WHS (Women’s Health Study),” JACC, 2010;55(21):2319-2327.
  8. Mozaffarian D et al, “Fish Intake and Risk of Incident Atrial Fibrillation,” Circulation, 2004; 110: 368-373.
  9. Frost L, Vestergaard P. Alcohol and Risk of Atrial Fibrillation or Flutter: A Cohort Study. Arch Intern Med. 2004;164(18):1993-1998.
  10. Healey JS, Baranchuk A, Crystal E, et al. Prevention of Atrial Fibrillation With Angiotensin-Converting Enzyme Inhibitors and Angiotensin Receptor Blockers: A Meta-Analysis. J Am Coll Cardiol. 2005;45(11):1832-1839.
  11. Siu C-W et al, “Prevention of atrial fibrillation recurrence by statin therapy in patients with lone atrial fibrillation after successful cardioversion,” The American Journal of Cardiology, V. 92, No. 11, 1 December 2003, Pages 1343–1345.
  12. Neilan TG, Farhad H, Dodson JA, Shah RV, Abbasi SA, Bakker JP, Michaud GF, van der Geest R, Blankstein R, Steigner M, John RM, Jerosch-Herold M, Malhotra A, Kwong RY. Effect of sleep apnea and continuous positive airway pressure on cardiac structure and recurrence of atrial fibrillation. J Am Heart Assoc. 2013; 2:e00042110.1161/JAHA.113.000421
  13. Fein AS, Shvilkin A, Shah D, Haffajee CI, Das S, Kumar K, Kramer DB, Zimetbaum PJ, Buxton AE, Josephson ME, Anter E. Treatment of obstructive sleep apnea reduces the risk of atrial fibrillation recurrence after catheter ablation. J Am Coll Cardiol. 2013; 62:300-305.
  14. Schwartz AR, Patil SP, Laffan AM, Polotsky V, Schneider H, and Smith PL, “Obesity and Obstructive Sleep Apnea Pathogenic Mechanisms and Therapeutic Approaches ,” Proc Am Thorac Soc. 2008 Feb 15; 5(2): 185–192.
  15. Kumanyika SK, Obarzanek E, Stettler N, Bell R, Field AE, Fortmann SP, Franklin BA, Gillman M, Lewis CE, Poston WC, Stevens J and Hong Y, “Population-Based Prevention of Obesity,” Circulation. 2008;118: 428-464.
  16. Pathak RK, Middeldorp ME, Meredith M, et al. Long-Term Effect of Goal-Directed Weight Management in an Atrial Fibrillation Cohort: A Long-Term Follow-Up Study (LEGACY). J Am Coll Cardiol. 2015;65(20):2159-2169.
  17. Jamaly et al, “Bariatric Surgery and the Risk of New-Onset Atrial Fibrillation in Swedish Obese Subjects, JACC, V. 68, No. 23 (December 2016), pp. 2497-2504.
  18. Mansour M, Karst E, Heist EK, Dalal N, Wasfy JH, Packer DL, Calkins J, Ruskin JN, Mahapatra S, “The Impact of First Procedure Success Rate on the Economics of Atrial Fibrillation Ablation,” JACC, V. 3, No. 2 (February 2017), pp. 129-138.




A study revealed at this year’s Heart Rhythm Society Meeting presented the first in-human results of a leadless implantable pacemaker. The device is about the size of a AAA battery and is implanted in the right ventricle. A limitation of current pacemakers is the reliance on implantable leads that can fracture or become infected. This device is the first step toward developing leadless pacing technologies. It remains to be seen how clinically useful this device will be but is expected to be available in Europe later this year.

Tiny Implant Chip
Image taken from http://www.wired.co.uk/news/archive/2013-03/20/implantable-chip-doctor.

A multidisciplinary Swiss team has developed a tiny implantable chip that can test blood and wirelessly transmit the information to doctors.

Giovanni de Micheli and Sandro Carrara of École Polytechnique Fédérale de Lausanne (EPFL) invented the 14mm-long device. The device is a chip fitted with five sensors and a radio transmitter and is powered via inductive coupling with a battery patch worn outside the body delivering a tenth of a watt in energy. The chip is Bluetooth-equipped to transfer the data picked up by the chip’s radio signals.

The researchers’ goals are to use the chip to monitor five different molecules which may represent five different disease states. This proof-of-concept device has exciting implications for the field of personalized medicine; each person’s biological signals can be recorded and therapy tailored for each individual.

The performance of complex cardiac procedures, such as advanced defibrillator placement, structural heart interventions, or arrhythmia ablation, is facilitated by the visualization of 3D anatomy.

     The performance of complex cardiac procedures, such as advanced defibrillator placement, structural heart interventions, or arrhythmia ablation, is facilitated by the visualization of 3D anatomy.  Providing 3D views of internal body structures and interventional devices in one image, this state-of-the-art system assists physicians in diagnosis, surgical planning, interventional procedures and treatment follow-up.     It permits better management of structural heart disease, streamlines interventional procedures, and minimizes radiation dose to physicians, staff and patients by selecting working views without fluoroscopy.  Patients can undergo 3D angiography of the coronary sinus to guide a biventricular defibrillator implantation with a left ventricular pacemaker lead.  Patients can also undergo 3D angiography of the left atrium and pulmonary veins to plan an atrial fibrillation arrhythmia ablation.