electroanatomic maps of the urinary bladder were developed using a noncontact mapping system ( ensite ) , which consisted of a roving catheter , a noncontact multielectrode array ( mea ) 64-electrode basket , and a custom designed amplifier system , with custom designed software , connected to a silicon graphics workstation . the reference electrode was located 16 cm distal to the basket . in cardiology application , a geometric model of the heart the current sensed by the proximal and distal ring electrodes mounted on the mea catheter created a location specific voltage distribution . the local medical ethics committee commisie mensgebonden onderzoek approved the study under number 46832.091.13/metc 2013/279 . three women aged 34 , 56 , and 82 years with lower urinary tract symptoms were included in the study . the first patient was a 34-year - old woman with oab symptoms ( urge incontinence ) ; her urodynamic study revealed detrusor overactivity ( do ) . the second patient was a 53-year - old woman with chronic neurogenic nonobstructive urinary retention . the bladder was drained using a 14-fr catheter , through which 200 ml of nacl 0.9% was injected into the bladder . the roving catheter was replaced by an urodynamic pressure catheter together with an mea catheter . the electrovesicography ( evg ) and the vesical pressure recordings were started simultaneously . during the measurement , evg data were sampled at a frequency of 1.2 khz ; the recorded signals were unipolar , with a bandpass filter between 0.1 and 300 hz . the measurements were performed using the ensite system , simultaneously with pressure flow study of the bladder using urodynamics systems ( medical measurement systems b.v . , the electrical signals obtained from the ensite system and the pressure signals obtained from the urodynamic system were manually synchronized . an envelope of a segment of the evg data was created using the absolute values of the mean of all channels recordings . the correlation coefficient for the correlation between the envelope of the evg data and the pressure signal of the bladder was calculated . the p - values were calculated by using two - tailed t - test with a significance level of 0.05 . data segments with detrusor pressure activity ( do and/or voiding act ) were selected ; the related evg and detrusor pressure ( pdet ) recording are shown in fig . scatter plots were made of the delay with the highest correlation coefficient , showing a positive correlation between the pdet and the envelope , and negative correlation between abdominal pressure ( pabd ) and the envelope ( fig . to our knowledge , the current study is the first attempt to measure the electrical activity within the urinary bladder in humans . some previous studies reported signals measurements : shafik et al . reported bladder signals of 1.6 mv , while hashitani et al .   reported bladder signals of 72 mv . this might be explained by the fact that the measured signals were estimated by the ensite software , which was originally developed to measure electric activity of the heart , which has a different geometry from the urinary bladder . another possibility to explain these low amplitudes could be the low conductivity of the saline fluid used to fill the bladder . the maximal distance for the ensite system to measure the electrical activity in the heart is 5 cm . 1 , the catheter is not located in the middle of the bladder , but rather lies against the bladder wall . this deviation from the central position of the mea catheter could lead to recording of one side only , the side closer to the catheter bladder activity . low bladder volumes might lead to direct contact between the mea catheter and the bladder wall , which might result in motion artifacts . therefore , we tried to maintain a maximal distance of 3.6 cm between the catheter tip and the bladder wall , which corresponds to a volume of about 200 ml . technical artifacts might be enormous for an accurate interpretation , especially in different bladder volumes and thicknesses . the tip of the electrode might be monitored with a camera using the video urodynamic study . ideally , the correlation coefficients of one segment should be significant for the detrusor pressure and insignificant for the abdominal pressure . however , the aim of this study was to test the possibility of developing the electroanatomical mapping for the bladder . in the next phase of the study , we will try to examine the electroanatomical features of the urinary bladders in healthy and disease status . electroanatomical mapping of the bladder might reveal crucial information about bladder pathophysiology for new management strategies for oab . for instance , electroanatomical mapping might indicate specific locations for the onabotulinum toxin a injections , thereby increasing the effectiveness of treatment and decreasing the costs . electroanatomical mapping of the bladder might be useful to differentiate the underlying pathologies in patients with bladder underactivity . minimal electrical activity could be observed , and significant weak to moderate correlation coefficients were found for the correlation between detrusor and abdominal pressures , and evg . the electrical propagation activity over the bladder wall could not be detected using the current method .
a noncontact mapping system ( ensite ) was used for electroanatomical mapping of the bladder simultaneously with pressure flow study in three women with lower urinary tract symptoms . 
 we selected the periods of obvious detrusor activity . 
 data were processed to remove baseline drift , and an envelope of electrovesicography ( evg ) data was created . 
 the correlation coefficient for the correlation between between the evg envelope and the detrusor pressure ( pdet ) was calculated . 
 bladder geometry was successfully created in all 3 patients . 
 simultaneous recording of evg and pressure flow data was successful in 1 patient . 
 scatter plots were made of the highest correlation coefficient , showing a positive correlation between the pdet and the envelope , and negative correlation between abdominal pressure ( pabd ) and the envelope . 
 minimal electrical activity could be observed . 
 significant weak to moderate correlation coefficients were found for the correlations between pdet and evg and between pabd and evg .