title: "Hands-Free" continuous transthoracic monitoring of pericardiocentesis using a novel ultrasound transducer.
abstract: BACKGROUND
  Pericardiocentesis can be monitored with a hand-held transducer. The purpose of this study was to assess the feasibility of monitoring pericardiocentesis using a novel ultrasound transducer, which can be attached to the chest wall, developed in our laboratory (CONTISON).
  
  
  METHODS
  We studied nine patients with large pericardial effusions. The 2.5-MHz transducer is spherical in its distal part and mounted in an external housing to permit steering in 360 degrees. The external housing is attached to the chest wall using an adhesive patch. The CONTISON transducer was placed at the cardiac apex and an apical four-chamber view obtained. Pericardiocentesis was performed from the subcostal position. The pericardial effusion was continuously imaged. Mitral inflow velocity signals were recorded before and after pericardiocentesis. When fluid was first obtained, 50 mL of fluid were discarded after which 5 mL of agitated saline was injected through the needle.
  
  
  RESULTS
  In the first patient the pericardiocentesis needle was seen in the left ventricular cavity. Saline injection produced a contrast effect in the left ventricle. The needle was gradually withdrawn until contrast was seen in the pericardial sac. A total of 1100 mL was removed without further complications. The second patient had clear fluid followed by blood stained aspirate. The echocardiogram revealed gradual appearance of granular echoes within the pericardial sac, suggestive of intrapericardial clot that was subsequently surgically evacuated. In the remaining seven patients, agitated saline produced a contrast effect in the pericardial sac indicative of proper needle position. Mitral flow velocity paradoxus was noted in five patients, and it resolved after pericardiocentesis in four patients. No adjustment of the transducer was required.
  
  
  CONCLUSIONS
  The CONTISON transducer permitted continuous monitoring of pericardiocentesis. This technique could potentially facilitate pericardiocentesis.
authors.affiliation: Division of Cardiology, LAC and USC Medical Center, Los Angeles, California 90822, USA. chandraratna@med.va.gov
authors.forename: P A N
authors.initials: PA
authors.lastname: Chandraratna
authors.forename: Sridhar
authors.initials: S
authors.lastname: Vijayasekaran
authors.forename: Prabhjoyt
authors.initials: P
authors.lastname: Brar
authors.forename: John
authors.initials: J
authors.lastname: Tzeng
mesh_terms: D000328:Adult; D004452:Echocardiography; D004867:Equipment Design; D006801:Humans; D008875:Middle Aged; D008991:Monitoring, Physiologic / Q000379:methods*; D010490:Pericardial Effusion / Q000000981:diagnostic imaging / Q000628:therapy*; D020519:Pericardiocentesis; D013909:Thorax; D014159:Transducers