when an amount of iodinated or other contrast agent solution ( e . g ., up to about 30 cc in one embodiment ) is introduced into the intact pericardial space , the vigorous motion of the heart distributes the contrast rapidly throughout the pericardial space . the contrast collects in groves and fissures on the surface of the heart . this includes the crevice between the left atrial and right atrial appendages and adjacent structures , as well as the space between the aorta and superior vena cava , and the crevice adjacent to the coronary sinus . these contrast - filled crevices are located adjacent to the coronary sulcus and the atrioventricular ( a - v ) groove , and provide radiographic markers that effectively demonstrate where these structures on the heart are located . a csd can then be placed accurately on the heart . irrigating and evacuating the pericardial sack repeatedly with normal saline can remove the contrast at the end of a procedure , if so desired . alternatively , the contrast can be left in place , and will drain from a chest tube over a period of time following surgery . any of a variety of methods can be used for introducing a contrast agent into the pericardial space . for example , tubular structures such as syringe needles and catheters can be inserted into the pericardial space through the pericardium . the contrast agent can then be delivered into the pericardial space through the tubular structure . one method utilizes a percutaneous puncture , either with a simple needle or a dedicated device configured to facilitate pericardial access , to instill iodinated contrast or other contrast agent into the intact pericardial space . an additional advantage of this procedure is that the contrast can help in detecting the presence of intrapericardial adhesions , which would preclude placement of a csd by a limited access approach . detecting adhesions prior to mini - thoracotomy would avoid the need to make an incision in a patient that could not undergo limited access implantation . a catheter placed in the intact pericardial space can be used to evacuate the contrast as well . if desired , irrigating and evacuating the pericardium through the catheter repeatedly with normal saline can provide more complete contrast removal . in another embodiment , access is gained into the pericardial space via the vasculature . this can include access across the right atrial appendage as shown in verrier , et al ., transatrial access to the normal pericardial space : a novel approach for diagnostic sampling , pericardiocentesis , and therapeutic interventions , circulation , nov . 24 , 1998 ; 98 ( 21 ): 2331 - 3 , or the ventricular wall as shown in baek et al ., augmentation of intrapericardial nitric oxide level by a prolonged - release nitric oxide donor reduces luminal narrowing after porcine coronary angioplasty , circulation , jun . 11 , 2002 ; 105 ( 23 ): 2779 - 84 . yet another embodiment utilizes a mini - thoracotomy placed in the appropriate intercostal space to allow visualization of the left ventricular apex . through this incision , the pericardial sack is opened to permit limited access placement of the csd . the pericardial edges of the apical opening are sutured to the thoracotomy margins . at this point , the patient is positioned so the apex of the heart is higher than the base . this can , for example , be done by positioning the bed in steep trendelenberg and rolling it to the patient &# 39 ; s right . iodinated contrast solution , ( e . g ., approximately 30 - 60 cc ), is introduced into the pericardial cavity . even though the pericardium has been opened , contrast still pools and collects in naturally occurring crevices and grooves on the surface of the heart . under fluoroscopy , this contrast agent provides anatomic landmarks that facilitate identification of the atrioventricular groove and accurate positioning of the csd . fig1 is a fluoroscopic image of a heart with contrast agent in the pericardial space in accordance with the invention . the heart boundary , pulmonary trunk , right atrium , left atrium and a - v groove are visible in the image . for purposes of comparison , fig2 is a fluoroscopic image of a heart without contrast agent . the heart boundary is apparent in fig2 , but specific structures such as the a - v groove are not visible . another embodiment of the invention for imaging the pericardial space in preparation for implanting a csd through a minimally - invasive surgical opening includes the use of ultrasound imaging capabilities . in one example , transesophageal echocardiography is used to image the pericardial space . more precisely , an ultrasound contrast agent such as solutions with microbubbles , or alternatively , carbon dioxide gas insufflation of the pericardial space , can be used to identify anatomical landmarks near the atrioventricular groove . another aspect of this approach may be the incorporation of ultrasound - opaque materials in the hemline of the csd to facilitate imaging of the position of the hemline of the device with respect to structures on the heart such as the a - v groove during deployment on the heart . one approach would be to incorporate radioopaque gas into the silicone band within the hemline of the csd . the band would then be visible under ultrasound imaging . radioopaque markers on the csd can also be used in connection with the imaging methods described above to accurately position csds on patents &# 39 ; hearts ( i . e ., by using the relative positions of the marked structures on the heart and the markers on the csd to move the csd into position ). still other embodiments of the invention include the use of an air - tight collar at the opening in the pericardium to provide access to the pericardial space ( i . e ., there is a relatively high - vacuum seal between the collar and the pericardium ). the collar can have an adhesive lip or other surface that secures the collar to the pericardium . in other embodiments the collar is sutured to the pericardium . although the embodiments of the invention described above use fluoroscopic and ultrasound imaging methods , other embodiments of the invention use other imaging methods such as , for example , mri and ct . other fluid ( e . g ., liquid or gas ) contrast agents suitable for use with the selected imaging methodology can also be used . in another embodiment of the invention contrast agent is introduced into the pericardial space after the csd is positioned on the heart . the heart , contrast agent and csd can then be imaged , and the resulting image used to assess the accuracy of csd placement on the heart . an alternative imaging location method and a tool 10 that can be used in connection with the method can be described with reference to fig3 , where a patient &# 39 ; s heart 12 is shown in phantom surrounded by pericardium 14 . as shown , the pericardium 14 is attached to the upper portions 16 of the heart 12 at locations near the great vessels ( not shown ), opposite the a - v groove 18 from the apex 20 of the heart . tool 10 includes an elongated flexible member 22 having a radioopaque marker 24 . marker 24 is located a predetermined distance from the end 26 of the member 22 . during use , the tool 10 is inserted into an opening such as 28 and advanced toward the intersection of the heart 12 and pericardium 14 . the flexible member 22 , which can be polymer , has sufficient rigidity to enable a surgeon or other clinician to advance the tool 10 into the pericardial space until the end 26 engages the intersection of the heart 12 and pericardium 14 . the distance between the marker 24 and the end 26 of the member 22 are known to the surgeon . since the distances between the intersection of the heart 12 and the pericardium 14 are generally known to the surgeon or clinician , the location of the marker 24 can be used as an indication of the location of the a - v groove 18 . when imaged , the marker 24 therefore provides an indicia that can be used to accurately locate the base end of a csd ( not shown ) on the patent &# 39 ; s a - v groove 18 . tools 10 having markers 24 at different locations with respect to the end 26 of the member 22 can be used for patients having differently sized hearts , and for different locations of the heart of a given patient . following the implantation of the csd , the tools 10 can be removed . air , carbon dioxide or other gases can be introduced ( e . g ., through the opening 28 ) to inflate the pericardial space and facilitate the accurate placement of the tools 10 . although not shown , more than one tool 10 can be inserted into the pericardial space to provide image markers . other embodiments ( not shown ) also include more than one marker 24 on the member 22 . in these embodiments the markers can be different from one another ( e . g ., in size or shape ) so they can be distinguished from one another on images . although the present invention has been described with reference to preferred embodiments , those skilled in the art will recognize that changes can be made in form and detail without departing from the spirit and scope of the invention .
a method for implanting a cardiac support device on a patient &# 39 ; s heart . an amount of contrast agent sufficient to cause structures on the heart to be visible upon fluoroscopic or other imaging is introduced into the pericardial space surrounding the heart . the heart and contrast agent are imaged to provide a visual indication of the location of the structures of the heart . the csd is placed on the heart using the visual indications provided by the imaging .