Identification of the Pericardiophrenic Vein During Cardiac Device Implant Procedures to Prevent Extracardiac Stimulation
Condition: Heart Failure
MeSH terms: Heart Failure
Study type: Observational

Summary: 
      The primary goal of this study is to develop techniques to identify the course of the phrenic
      nerve in patients already undergoing cardiac resynchronization therapy (CRT) implantation or
      candidates for future CRT devices undergoing implantable cardioverter-defibrillator (ICD) or
      pacemaker implantation. Specifically, the study intends to identify the location and course
      of the left pericardiophrenic vein, and thus the left phrenic nerve, to guide the location
      for coronary vein lead placement and minimize the risk of phrenic nerve stimulation.
    

Detailed description: 
      Phrenic nerve stimulation from cardiac resynchronization therapy (CRT) is a common adverse
      event occurring in 1.5-3% of patients and sometimes as high as 10%. Phrenic nerve stimulation
      is frequently observed during the implantation procedure but often appears shortly after
      implantation as well. Clinically, dyspnea, cough, and hiccups can occur, some of which are
      uncomfortable and not tolerated by the patient for very long periods of time. Resolution of
      these clinical outcomes requires repositioning the left coronary vein lead in a second
      procedure with its attendant serious clinical sequelae. As CRT leads become smaller the
      incidence of phrenic nerve stimulation is likely to increase.

      The risk of phrenic nerve stimulation (PNS) exists during CRT implantation and is only
      minimally dependent of the type of coronary lead and highly dependent upon location of the
      left coronary vein lead in relationship to the left phrenic nerve and stimulation strength.
      Tedrow et al. demonstrated in a cohort of 71 patients PNS can reach 16% if stimulation
      strength is increased to maximize mechanical benefit of CRT. No current methods have been
      able to predict PNS, the one likely method of preventing PNS is to identify the location of
      the phrenic nerve in the specific patient, as confirmed by visualization and ability to
      stimulate the phrenic nerve and by maximizing the distance between the coronary vein lead
      position and nerve.

      In order to reduce the incidence of phrenic nerve stimulation, Vaseghi performed
      non-selective injections of contrast media and was able to identify the left
      pericardiophrenic vein in only about 12% of patients undergoing biventricular pacemaker
      placement. However, in these patients, identification of the left pericardiophrenic vein
      provides a landmark for positioning of the left ventricular (LV) lead that totally eliminated
      the incidence of phrenic nerve pacing.

      The relationship of cardiac structures to the right and left phrenic nerves is generally
      known but is significantly variable between patients. There is no imaging or other clinically
      available modality that allows the physician to identify the location of the left phrenic
      nerve and attempt to avoid it during the left coronary vein lead implant procedure.

      The pericardiophrenic veins are a deep collateral venous drainage of the pericardium, pleura
      and diaphragm and lie adjacent the phrenic nerves on both the right and left sides between
      the parietal pericardium and adjacent pleura. The ostium of the left pericardiophrenic vein
      is usually in the left brachiocephalic vein opposite the entrance of the left jugular vein.
      The left phrenic vein is located in the general vicinity of the thymic veins which often have
      multiple ostia in close proximity. There are several case reports in the literature of
      inadvertent cannulation of the pericardiophrenic veins with Swan-Ganz catheters, central
      venous catheters and one report of cannulation with a pacing lead leading to inadvertent
      phrenic nerve pacing.

      The primary goal of this study is to develop techniques to identify the course of the phrenic
      nerve in patients already undergoing cardiac resynchronization therapy (CRT) implantation or
      candidates for future CRT devices undergoing implantable cardioverter-defibrillator (ICD) or
      pacemaker implantation. Specifically, the study intends to identify the location and course
      of the left pericardiophrenic vein, and thus the left phrenic nerve, to guide the location
      for coronary vein lead placement and minimize the risk of phrenic nerve stimulation.
    

Observational model: Case-Only
Time perspective: Prospective
Sampling method: Non-Probability Sample
Study population: 
        Patients currently under the care of an electrophysiologist or cardiac device implanter who
        are scheduled to receive a CRT device, or those patients receiving an ICD or pacemaker
        device who are future candidates for CRT device implantation.
      
Keywords: Cardiac resynchronization therapy