catheter ablation has become a standard therapy in the treatment of many arrhythmias . while different ablation strategies have been proposed and are currently applied , all ablation procedures share one commonality in their necessity for the use of fluoroscopy to visualize catheters .
heavy reliance on the use of live x - ray for ablation procedures was alleviated in the 1990s with the advent of 3d electroanatomical mapping systems ( eams ) that helped to significantly reduce radiation time and dosage .
integration of cardiac imaging using magnetic resonance imaging ( mri ) and computed tomography ( ct ) was shown to even further reduce fluoroscopy exposure during ablation procedures .
more recently , a new technology for catheter visualization , called the mediguide-(mg ) technology , has been introduced that can further facilitate reduction in radiation exposure .
briefly , single - coil sensors embedded in the catheter tip can be accurately localized by an electromagnetic field .
information about the 3d position and orientation of the tools is then transferred to the fluoroscopy system and is used to visualize the catheter tip in a virtual bi - planar view projected on 2 pre - recorded cine loops .
it has been previously shown that the application of the mg technology can lead to a significant reduction in fluoroscopy burden by using diagnostic catheters in atrial flutter and by using both diagnostic and ablation catheters in several supraventricular tachycardias ( svt ) and atrial fibrillation ( af ) cases .
there may be concerns that the application of the non - fluoroscopic catheter visualization ( nfcv ) technology may increase procedural risks in the absence of the catheter shaft visualization and catheter localization that is solely based on the location of the catheter tip .
it was demonstrated that the complication rate is equal or even lower to procedures performed with conventional tools .
this could be explained by a limitation of conventional procedures : only in a certain percentage of the procedure catheters will be  visible  .
this changed by application of nfcv technology since catheters will be visible during the entire procedure on this virtual biplanar view . in this protocol , we perform an ablation of atrial fibrillation in a patient with paroxysmal , drug - refractory and highly symptomatic atrial fibrillation .
the goal of this protocol is to achieve the same endpoints as in a conventional procedure , i.e. , isolation of all pulmonary veins with proven bi - directional block , and to reduce fluoroscopy exposure for the patient by > 90% as compared to conventional settings via the additional use of the nfcv technology .
all patients signed an informed consent form after all typical complications of an ablation procedure such as pericardial effusion , vascular complications at the access site , stroke / tia , and esophago - atrial fistula , were explained .
no patient subgroup had to be excluded ( e.g. , patients with pacemakers or icd ) ; only general contraindications for af ablation procedures ( e.g. , contraindication for anticoagulation , hyperthyreosis , valvular af , etc . ) had to be addressed .
on the day of hospital admission , perform a routine physical exam including resting ecg , blood analysis , transesophageal echo and a contrast - enhanced ct scan of the heart on the patient .
if novel anticoagulants are used , skip either 1 dose ( rivaroxaban ) or 2 doses ( dabigatran and apixaban ) before the procedure .
place the 3d eams patches on the patient per manufacturer s instructions on the thorax ( front and back ; left and right ) , neck , and belly .
monitor oxygen saturation using a finger clip , as well as the non - invasive blood pressure .
administer midazolam ( 2 - 3 mg , i.v . ) and fentanyl ( 0.025 mg , i.v . ) as premedication to slightly sedate the patient and to provide some analgesics during the puncture of the femoral vessels .
start the procedure with the injection of 40 ml of 1% mepivacain to the left and right groin areas .
start the puncture for venous access 1 cm medial to the femoral artery , 1 cm below the connection between symphysis and crista iliaca anterior superior .
perform two 7f punctures in the left femoral vein for placing two diagnostic catheters : 1 steerable decapolar catheter for the coronary sinus ( cs ) and 1 steerable decapolar catheter for the right ventricular apex . after a successful puncture of the vessels ,
advance a guidewire , remove the puncture needle and place the sheath over the wire per the seldinger technique.next , perform 2 punctures on the right side : a 4f puncture in the right femoral artery for invasive blood pressure measurements , and an 11f one in the right femoral vein for the transseptal sheath . before inserting the 11f sheath ,
control the intravasal position of the wire using fluoroscopy and then place the sheath . 
 
perform two 7f punctures in the left femoral vein for placing two diagnostic catheters : 1 steerable decapolar catheter for the coronary sinus ( cs ) and 1 steerable decapolar catheter for the right ventricular apex . after a successful puncture of the vessels ,
advance a guidewire , remove the puncture needle and place the sheath over the wire per the seldinger technique .
next , perform 2 punctures on the right side : a 4f puncture in the right femoral artery for invasive blood pressure measurements , and an 11f one in the right femoral vein for the transseptal sheath . before inserting the 11f sheath ,
check the activated clotting time ( act ) every 20 min ; the target for the anticoagulation is an act between 250 and 350 sec . if necessary , administer boluses of heparin according to act measurements . during the procedure , maintain the patient in a deep analgosedation using midazolam ( 2 - 5 mg ) , fentanyl ( 0.05 - 0.1 mg ) and propofol ( bolus 0.5 mg / kg and constant basal rate of 0.5 mg / kg / h ) . acquire 2 live fluoroscopy or cine loops using the x - ray fluoroscopy system in a right anterior oblique projection ( rao 15 ) and a left anterior oblique projection ( lao 50 ) , each approximately 3 sec long ( figure 3 and video 1 ) .
note : the nfcv projects the catheter tips on these pre - recorded cine loops allowing a non - fluoroscopic placement of the diagnostic catheters .
place one of the diagnostic catheters in the cs by first advancing the catheter tip to the superior vena cava ( svc ) , then pulling it back slowly and deflecting it to bring it close to the bundle of his .
deflect the catheter to its maximum allowable curve and perform a clockwise rotation to bring the tip to the cs ostium .
advance the catheter as deep as possible in the cs to achieve a stable position . then , place a landmark on the catheter tip using the nfcv system to mark the location.use the other diagnostic catheter to place landmarks for superior vena cava ( svc ) , inferior vena cava ( ivc ) and fossa ovalis ( see figure 1 ) . 
 
deflect the catheter to its maximum allowable curve and perform a clockwise rotation to bring the tip to the cs ostium .
advance the catheter as deep as possible in the cs to achieve a stable position . then , place a landmark on the catheter tip using the nfcv system to mark the location .
use the other diagnostic catheter to place landmarks for superior vena cava ( svc ) , inferior vena cava ( ivc ) and fossa ovalis ( see figure 1 ) .
perform a trans - atrial septal puncture using a long steerable sheath . insert a long guidewire to the svc and verify the position with fluoroscopy .
advance the steerable sheath over the wire to the junction between the svc and the right atrium ( ra ) .
insert a long needle into the dilator , pull back the sheath until it  jumps  into the fossa ovalis.perform the puncture by advancing the needle and injecting contrast dye ( 15 ml of ultravist 300 ) to verify the correct position of the sheath in the left atrium ( la).once the needle tip is in the la , advance the dilator to la , disconnect it from the sheath and advance the sheath over the dilator into the la .
deflect the sheath and slowly remove the needle and dilator from the sheath.aspire 10 ml of blood from the sheath and carefully flush the sheath with heparinized saline .
flush the sheath with heparinized saline constantly at a flow rate of 2 ml / hr . note : the diagnostic catheter is used for electroanatomical reconstruction of the la and pulmonary venous anatomy .
coronary sinus catheter remains in place and serves as the reference catheter for the 3d mapping system . 
 
advance the steerable sheath over the wire to the junction between the svc and the right atrium ( ra ) .
insert a long needle into the dilator , pull back the sheath until it  jumps  into the fossa ovalis .
perform the puncture by advancing the needle and injecting contrast dye ( 15 ml of ultravist 300 ) to verify the correct position of the sheath in the left atrium ( la ) .
once the needle tip is in the la , advance the dilator to la , disconnect it from the sheath and advance the sheath over the dilator into the la . deflect the sheath and
aspire 10 ml of blood from the sheath and carefully flush the sheath with heparinized saline .
flush the sheath with heparinized saline constantly at a flow rate of 2 ml / hr . note : the diagnostic catheter is used for electroanatomical reconstruction of the la and pulmonary venous anatomy .
coronary sinus catheter remains in place and serves as the reference catheter for the 3d mapping system .
insert the long sheath in the superior pulmonary veins and perform 2 new fluoroscopy or cine loops in rao 15 ( right pv ) and lao 50 ( left pv ) during injection of 15 ml of contrast dye ( ultravist 300 ) .
map anatomical landmarks in the la carefully and use for this co - registration process .
for example , use the junction of the left inferior pulmonary vein ( lipv ) to the la body . take at least 10 - 15 points for the fusion process and then double - check and optimize the co - registration process with the roving catheter . upon completion
, the segmented ct model is positioned at an anatomically correct position in 3d space . 
 
for example , use the junction of the left inferior pulmonary vein ( lipv ) to the la body .
take at least 10 - 15 points for the fusion process and then double - check and optimize the co - registration process with the roving catheter . upon completion
, the segmented ct model is positioned at an anatomically correct position in 3d space .
place a temperature probe with 3 thermocouples trans - orally to measure the intra - luminal intra - esophageal temperature at the level of the la .
perform ablation around the ipsilateral pulmonary veins by using power settings of 35 w ( anterior ) and 25 w ( posterior ) at an irrigation rate of 17 ml / min .
if the intra - luminal temperature exceeds 39 c , immediately stop the ablation and adjust the power settings , lowering the minimum power to be 20 w. in case of temperature rise despite reduction of energy settings , consider modifying the lesion setting to go more antral if it is too close to the esophagus .
if the temperature still exceeds 41 c , perform an esophagoscopy the day after the ablation to exclude mucosal thermal damage which could develop to an esophago - atrial fistula . 
 
if the temperature still exceeds 41 c , perform an esophagoscopy the day after the ablation to exclude mucosal thermal damage which could develop to an esophago - atrial fistula .
check the completeness of the pulmonary vein isolation using a decapolar circular catheter by pacing maneuvers at maximum power ( usually 10 ma / msec ) from all bipoles of the spiral catheter .
make sure that the stimulus does not capture the la by checking signals on the cs catheter .
gaps  in the lesion set : move the ablation catheter around the circumferential lesions and stimulate with maximum output from the tip of the ablation catheter . if the atrium is captured , start ablation until the local capture disappears .
use this  pace - and - ablate-technique around all pulmonary veins . 
  if necessary , detect and close  gaps  in the lesion set : move the ablation catheter around the circumferential lesions and stimulate with maximum output from the tip of the ablation catheter .
once the isolation line around the pulmonary veins is completed , perform a voltage map of the left atrium to determine a healthy atrium ( shown in purple ) or a fibrotic atrium ( shown in blue , yellow , and grey ) [ see figure 1 and 2 ] . use the cut - off values 0.5 mv for normal tissue and 0.2 mv for scar tissue . use the ablation catheter or the diagnostic catheter and start in the pulmonary vein antrum .
make sure that there is sufficient contact with the catheter tip and register the local signal amplitude to the 3d mapping system . for a normal sized la , take points covering the entire la body and pv antrum ( 100 - 150 points ) . 
 
use the ablation catheter or the diagnostic catheter and start in the pulmonary vein antrum .
make sure that there is sufficient contact with the catheter tip and register the local signal amplitude to the 3d mapping system .
for a normal sized la , take points covering the entire la body and pv antrum ( 100 - 150 points ) .
perform a test for inducibility with 20 sec burst - pacing from the coronary sinus with cycle lengths of 300 msec , 250 msec and 200 msec or to atrial refractory time .
if a stable atrial tachycardia or atrial flutter is induced , map and ablate accordingly .
if atrial fibrillation is induced , perform an electrical cardioversion ( with 200 j biphasic shock ) and terminate the procedure .
antagonize heparin by injecting protaminsulfat ( 10,000 iu , i.v . ) and remove the sheaths from the groin .
after removal of the sheaths manually , compress the puncture sites on both sides . check if there is still active bleeding after 5 min . if not , continue compression for at least an additional 5 min and place the pressure bandage for 6 hr .
after removal of the pressure bandage and checking the femoral vessels clinically ( palpation and auscultation ) , deliver the next dose of anticoagulant drugs ( warfarin or novel anticoagulants ) .
on the day of hospital admission , perform a routine physical exam including resting ecg , blood analysis , transesophageal echo and a contrast - enhanced ct scan of the heart on the patient .
if novel anticoagulants are used , skip either 1 dose ( rivaroxaban ) or 2 doses ( dabigatran and apixaban ) before the procedure .
place the 3d eams patches on the patient per manufacturer s instructions on the thorax ( front and back ; left and right ) , neck , and belly .
monitor oxygen saturation using a finger clip , as well as the non - invasive blood pressure .
perform disinfection of the groin region . administer midazolam ( 2 - 3 mg , i.v . ) and fentanyl ( 0.025 mg , i.v . ) as premedication to slightly sedate the patient and to provide some analgesics during the puncture of the femoral vessels .
start the procedure with the injection of 40 ml of 1% mepivacain to the left and right groin areas .
start the puncture for venous access 1 cm medial to the femoral artery , 1 cm below the connection between symphysis and crista iliaca anterior superior .
perform two 7f punctures in the left femoral vein for placing two diagnostic catheters : 1 steerable decapolar catheter for the coronary sinus ( cs ) and 1 steerable decapolar catheter for the right ventricular apex . after a successful puncture of the vessels , advance a guidewire , remove the puncture needle and place the sheath over the wire per the seldinger technique.next , perform 2 punctures on the right side : a 4f puncture in the right femoral artery for invasive blood pressure measurements , and an 11f one in the right femoral vein for the transseptal sheath . before inserting the 11f sheath ,
control the intravasal position of the wire using fluoroscopy and then place the sheath . 
  perform two 7f punctures in the left femoral vein for placing two diagnostic catheters : 1 steerable decapolar catheter for the coronary sinus ( cs ) and 1 steerable decapolar catheter for the right ventricular apex .
after a successful puncture of the vessels , advance a guidewire , remove the puncture needle and place the sheath over the wire per the seldinger technique .
next , perform 2 punctures on the right side : a 4f puncture in the right femoral artery for invasive blood pressure measurements , and an 11f one in the right femoral vein for the transseptal sheath . before inserting the 11f sheath ,
check the activated clotting time ( act ) every 20 min ; the target for the anticoagulation is an act between 250 and 350 sec .
if necessary , administer boluses of heparin according to act measurements . during the procedure , maintain the patient in a deep analgosedation using midazolam ( 2 - 5 mg ) , fentanyl ( 0.05 - 0.1 mg ) and propofol ( bolus 0.5 mg / kg and constant basal rate of 0.5 mg / kg / h ) .
acquire 2 live fluoroscopy or cine loops using the x - ray fluoroscopy system in a right anterior oblique projection ( rao 15 ) and a left anterior oblique projection ( lao 50 ) , each approximately 3 sec long ( figure 3 and video 1 ) .
note : the nfcv projects the catheter tips on these pre - recorded cine loops allowing a non - fluoroscopic placement of the diagnostic catheters .
place one of the diagnostic catheters in the cs by first advancing the catheter tip to the superior vena cava ( svc ) , then pulling it back slowly and deflecting it to bring it close to the bundle of his .
deflect the catheter to its maximum allowable curve and perform a clockwise rotation to bring the tip to the cs ostium .
advance the catheter as deep as possible in the cs to achieve a stable position . then , place a landmark on the catheter tip using the nfcv system to mark the location.use the other diagnostic catheter to place landmarks for superior vena cava ( svc ) , inferior vena cava ( ivc ) and fossa ovalis ( see figure 1 ) . 
 
deflect the catheter to its maximum allowable curve and perform a clockwise rotation to bring the tip to the cs ostium .
advance the catheter as deep as possible in the cs to achieve a stable position . then , place a landmark on the catheter tip using the nfcv system to mark the location .
use the other diagnostic catheter to place landmarks for superior vena cava ( svc ) , inferior vena cava ( ivc ) and fossa ovalis ( see figure 1 ) . perform a trans - atrial septal puncture using a long steerable sheath .
advance the steerable sheath over the wire to the junction between the svc and the right atrium ( ra ) .
insert a long needle into the dilator , pull back the sheath until it  jumps  into the fossa ovalis.perform the puncture by advancing the needle and injecting contrast dye ( 15 ml of ultravist 300 ) to verify the correct position of the sheath in the left atrium ( la).once the needle tip is in the la , advance the dilator to la , disconnect it from the sheath and advance the sheath over the dilator into the la .
deflect the sheath and slowly remove the needle and dilator from the sheath.aspire 10 ml of blood from the sheath and carefully flush the sheath with heparinized saline .
flush the sheath with heparinized saline constantly at a flow rate of 2 ml / hr . note : the diagnostic catheter is used for electroanatomical reconstruction of the la and pulmonary venous anatomy .
coronary sinus catheter remains in place and serves as the reference catheter for the 3d mapping system . 
 
advance the steerable sheath over the wire to the junction between the svc and the right atrium ( ra ) .
insert a long needle into the dilator , pull back the sheath until it  jumps  into the fossa ovalis .
perform the puncture by advancing the needle and injecting contrast dye ( 15 ml of ultravist 300 ) to verify the correct position of the sheath in the left atrium ( la ) .
once the needle tip is in the la , advance the dilator to la , disconnect it from the sheath and advance the sheath over the dilator into the la .
aspire 10 ml of blood from the sheath and carefully flush the sheath with heparinized saline .
flush the sheath with heparinized saline constantly at a flow rate of 2 ml / hr . note : the diagnostic catheter is used for electroanatomical reconstruction of the la and pulmonary venous anatomy .
coronary sinus catheter remains in place and serves as the reference catheter for the 3d mapping system .
insert the long sheath in the superior pulmonary veins and perform 2 new fluoroscopy or cine loops in rao 15 ( right pv ) and lao 50 ( left pv ) during injection of 15 ml of contrast dye ( ultravist 300 ) . perform fusion of the electroanatomical map with 3d reconstructed ct anatomy .
map anatomical landmarks in the la carefully and use for this co - registration process .
for example , use the junction of the left inferior pulmonary vein ( lipv ) to the la body . take at least 10 - 15 points for the fusion process and then double - check and optimize the co - registration process with the roving catheter . upon completion
, the segmented ct model is positioned at an anatomically correct position in 3d space . 
 
for example , use the junction of the left inferior pulmonary vein ( lipv ) to the la body . take at least 10 - 15 points for the fusion process and then double - check and optimize the co - registration process with the roving catheter . upon completion
, the segmented ct model is positioned at an anatomically correct position in 3d space .
place a temperature probe with 3 thermocouples trans - orally to measure the intra - luminal intra - esophageal temperature at the level of the la .
perform ablation around the ipsilateral pulmonary veins by using power settings of 35 w ( anterior ) and 25 w ( posterior ) at an irrigation rate of 17 ml / min .
if the intra - luminal temperature exceeds 39 c , immediately stop the ablation and adjust the power settings , lowering the minimum power to be 20 w. in case of temperature rise despite reduction of energy settings , consider modifying the lesion setting to go more antral if it is too close to the esophagus .
if the temperature still exceeds 41 c , perform an esophagoscopy the day after the ablation to exclude mucosal thermal damage which could develop to an esophago - atrial fistula . 
 
if the temperature still exceeds 41 c , perform an esophagoscopy the day after the ablation to exclude mucosal thermal damage which could develop to an esophago - atrial fistula .
check the completeness of the pulmonary vein isolation using a decapolar circular catheter by pacing maneuvers at maximum power ( usually 10 ma / msec ) from all bipoles of the spiral catheter .
make sure that the stimulus does not capture the la by checking signals on the cs catheter .
if necessary , detect and close  gaps  in the lesion set : move the ablation catheter around the circumferential lesions and stimulate with maximum output from the tip of the ablation catheter .
use this  pace - and - ablate-technique around all pulmonary veins . 
  if necessary , detect and close  gaps  in the lesion set : move the ablation catheter around the circumferential lesions and stimulate with maximum output from the tip of the ablation catheter .
once the isolation line around the pulmonary veins is completed , perform a voltage map of the left atrium to determine a healthy atrium ( shown in purple ) or a fibrotic atrium ( shown in blue , yellow , and grey ) [ see figure 1 and 2 ] .
use the cut - off values 0.5 mv for normal tissue and 0.2 mv for scar tissue . use the ablation catheter or the diagnostic catheter and start in the pulmonary vein antrum .
make sure that there is sufficient contact with the catheter tip and register the local signal amplitude to the 3d mapping system . for a normal sized la , take points covering the entire la body and pv antrum ( 100 - 150 points ) . 
 
use the ablation catheter or the diagnostic catheter and start in the pulmonary vein antrum .
make sure that there is sufficient contact with the catheter tip and register the local signal amplitude to the 3d mapping system . for a normal sized la , take points covering the entire la body and pv antrum ( 100 - 150 points ) .
perform a test for inducibility with 20 sec burst - pacing from the coronary sinus with cycle lengths of 300 msec , 250 msec and 200 msec or to atrial refractory time .
if a stable atrial tachycardia or atrial flutter is induced , map and ablate accordingly .
if atrial fibrillation is induced , perform an electrical cardioversion ( with 200 j biphasic shock ) and terminate the procedure .
remove the transseptal sheath and catheters . antagonize heparin by injecting protaminsulfat ( 10,000 iu , i.v . ) and remove the sheaths from the groin .
after removal of the sheaths manually , compress the puncture sites on both sides . check if there is still active bleeding after 5 min . if not , continue compression for at least an additional 5 min and place the pressure bandage for 6 hr .
after removal of the pressure bandage and checking the femoral vessels clinically ( palpation and auscultation ) , deliver the next dose of anticoagulant drugs ( warfarin or novel anticoagulants ) .
the patients are under deep analog - sedation , meaning that they are sleeping , receiving analgesics but breathe spontaneously .
if all endpoints including bi - directional block in all pulmonary veins , healthy left atrial tissue , and non - inducibility of atrial fibrillation or atrial flutter are achieved , patients have about a 75% probability of freedom from atrial fibrillation recurrence after 12 months .
if the left atrium has fibrotic tissue with low voltage areas ( see figure 2 ) , the chances of permanent freedom from arrhythmias decrease compared to patients with healthy left atrial tissue ( see figure 3 ) .
typically , patients can be discharged 24 hr after the procedure . in the first 4 - 6 weeks after the ablation procedure
after 6 weeks , the likely outcomes of the ablation procedure are evident . in most cases ,
all medical anti - arrhythmic treatments are discontinued on the day of the ablation procedure .
oral anticoagulation is mandatory and needs to be continued after the ablation procedure irrespective of the individual s stroke risk for at least 3 months .
figure 1 : ablation of atrial fibrillation using nfcv technology . left and middle : catheter visualization using the nfcv technology : ablation catheter ( red tip ) in the left superior pulmonary vein ( lspv , blue marker ) .
ablation catheter ( green halo ) placed in the left superior pulmonary vein close to the ridge to the left atrial appendage .
3d reconstructed ct with low - voltage areas at the posterior wall of the left atrium and in the mitral isthmus region indicating areas of previous ablation .
a color - coded voltage map is shown with purple for healthy tissue ( electrograms > 0.5 mv ) and grey for scar tissue ( electrograms < 0.2 mv ) .
electrogram amplitudes > 0.2 mv and < 0.5 mv are displayed in yellow , red , and blue .
2 short cine loops ( 3 sec each ) are recorded and are used as the dynamic background for catheter visualization . specially - designed catheters with miniaturized sensors at the tip are inserted in the patient and visualized by the nfcv system .
radiation exposure for interventional cardiologists and electrophysiologists is an underestimated risk because of its unpredictable side - effects .
current literature reveals a higher incidence of left - sided brain - tumors among this subgroup of clinicians , suggesting that the proximity of the left hemisphere to the x - ray source may be a culprit .
the latency between radiation exposure and diagnosis of neoplasia has been reported to be 20 years or more .
therefore , today s interventionalists should use all technological options to reduce radiation exposure to a minimum . the nfcv system can help reduce fluoroscopy exposure without affecting procedure time with a workflow that was adapted several times over the past 3 years in order to minimize radiation exposure according to the alara principle .
3d mapping systems can help to improve the understanding of complex 3-dimensional structures , but the basic orientation for the operator is generated using conventional fluoroscopy .
the transseptal puncture remains the largest contributing step ( 75 - 80% ) of the radiation dose during these procedures since no sensor - equipped material for use with nfcv technology is currently available .
especially in unexperienced hands this represents the most critical step in that procedure- other imaging modalities ( such as intracardiac or transesophageal echo ) can contribute to safe punctures and low complication rates .
the nfcv is not only used in ablation procedures but also in complex implantations such as cardiac resynchronization therapy ( crt ) . in these procedures ,
the system allows the reduction of fluoroscopy burden by 75 - 80% compared to conventional implantations . a recent publication could show that after a learning curve of 30 - 40 procedures a median fluoroscopy time of 1.1 min for 50 consecutive patients is feasible and safe
this was confirmed when extending the data acquisition to > 500 patients ( see figure 4 ) . 


figure 4 : 
 please click here to view a larger version of this figure . 
 
the limitation of the current available system is that only the tips of the catheters are visualized .
unexperienced operators will probably not be able to interpolate from the orientation of the tip to know what the position of the catheter shaft will be .
only a limited choice of catheters are currently available- therefore only a limited number of different procedures is suitable using nfcv technology . in near future more devices and tools will be available that are equipped with a sensor to be visualized non - fluoroscopically .
the system here basically works as a cardiovascular platform for different procedures ;  electrophysiology is just the first application that has been introduced .
 a technological platform ( mediguide ) has been recently introduced for non - fluoroscopic catheter tracking . in several studies 
 , we have demonstrated that the application of this non - fluoroscopic catheter visualization system ( nfcv ) reduces fluoroscopy time and dose by 90 - 95% in a variety of electrophysiology ( ep ) procedures . 
 this can be of relevance not only to the patients , but also to the nurses and physicians working in the ep lab . 
 furthermore , in a subset of indications such as supraventricular tachycardias , nfcv enables a fully non - fluoroscopic procedure and allows the lab staff to work without wearing lead aprons . with this protocol , 
 we demonstrate that even complex procedures such as ablations of atrial fibrillation , that are typically associated with fluoroscopy times of > 30 min in conventional settings , can safely be performed with a reduction of > 90% in fluoroscopy exposure by the additional use of nfcv . 