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right ventricular ( rv ) pacing can lead to progressive left ventricular ( lv ) systolic dysfunction and heart failure due to electrical and mechanical dyssynchrony .
the deleterious effect of rv pacing on lv systolic function has been termed pacing - induced cardiomyopathy ( picm ) .
upgrading to biventricular pacing ( bivp ) reverses lv remodeling in patients with picm as it does in primary bivp recipients . on the other hand , in patients requiring cardiac resynchronization therapy ( crt ) , permanent his - bundle pacing ( hbp )
an 87-year - old woman with chronic heart failure and chronic kidney disease ( ckd ) was admitted to our hospital due to worsening dyspnea and lower extremity edema .
she had undergone permanent pacemaker implantation 6 years before because of 2:1 atrioventricular ( av ) block with a narrow qrs complex ( fig .
her medications included torasemide 4  mg , carvedilol 5  mg , and valsartan 40  mg .
a 12-lead electrocardiogram ( ecg ) showed atrial sensed ventricular pacing with a qrs duration of 140  ms ( fig .
pacemaker interrogation revealed that her native cardiac rhythm remained 2:1 av block with a narrow qrs , and ventricular pacing was greater than 99% .
chest x - ray revealed an enlarged cardiothoracic ratio ( ctr ) of 60% and bilateral pleural effusions ( fig .
coronary angiography and echocardiography performed before pacemaker implantation had revealed normal coronary arteries and a lvef of 65% , respectively .
further medical treatment with carperitide and intravenous furosemide did not improve the pleural effusions or lvef .
because the patients native cardiac rhythm remained 2:1 av block with a narrow qrs , we thought hbp would be better than bivp , and thus we attempted permanent hbp as the first - line treatment . although the his bundle ( hb ) electrogram could not be clearly identified , narrow qrs complexes suggesting nonselective hbp ( his capture fused with local ventricular septal capture ) were easily obtained using a selectsecure 3830 screw - in lead inserted through a selectsite c304 deflectable catheter ( medtronic , minneapolis , mn , usa ) by pace - mapping the av septum .
the pacing thresholds of the hb and the adjacent septal myocardium were 1.0  v/0.4  ms and 0.75  v/0.4  ms , respectively .
the hb pacing lead was connected to the lv port of a biventricular ( biv ) pacemaker ( viva crt - p , medtronic ) .
we chose this device because it has no sensing ability in the lv lead ( in this case , the hb lead ) and thus does not cause double counts with a delay in the hv interval and safety pacing in rv pacing .
this delay was set to provide back - up rv pacing in case the hb pacing lead failed to capture the right ventricle .
after the 1-week follow - up , the pacing threshold of the hb had improved slightly to 0.75  v/0.4  ms , while that of the adjacent septal myocardium was 1.0  v/0.4  ms .
echocardiography at 1 month after the upgrade demonstrated improvement in the patients lvef from 33% to 45% , and the brain natriuretic peptide level decreased from 1208  pg / ml to 97  pg / ml . at the
chest x - ray revealed improvement of the ctr to 45% without pleural effusion ( fig .
the pacing threshold of the hb remained stable at 0.75  v/0.4  ms and that of the adjacent septal myocardium was 1.0  v/0.4  ms .
upgrading to bivp has been reported as an effective therapy for picm ; however , about 3040% of patients do not respond to this treatment .
in addition , performing bivp can be challenging with a long procedural time and might even be impossible due to the coronary sinus anatomy .
rehwinkel et al . demonstrated that upgrading to hbp could be an effective alternative to bivp for picm with preserved his - purkinje conduction . because our patients native rhythm remained 2:1 av block with a narrow qrs
, we attempted hbp as the first - line treatment based on the assumption that his - purkinje conduction might be preserved .
another benefit of hbp in this patient with ckd is that the use of iodinated contrast media could be avoided .
hbp using a deflectable lead delivery system was easily achieved with a fluoroscopic time of 8 minutes .
lustgarten et al . reported that hb pacing lead placement with this system was no more difficult and took less time to implant than placement of a lv lead .
our patient is thought to be a super - responder to crt by hbp although the form of hbp was nonselective
. however , there seems to be no significant clinical difference between selective hbp ( his - only capture ) and nonselective hbp because both forms do not alter physiological impulse conduction and possibly maintain rapid and synchronous lv activation .
indeed , catanzariti et al . reported that no difference was observed between the two forms of hbp at acute measures of dyssynchrony .
most patients with picm having a native narrow qrs have preserved his - purkinje conduction , and therefore upgrading to hbp would be expected to restore physiological synchronous lv activation .
recently , vijayaraman et al . demonstrated that his - purkinje conduction could be normalized by permanent hbp in 76% of patients with infranodal av block and a wide qrs complex , indicating intra - his block .
this finding suggests that many patients with picm having a native wide qrs might have preserved distal his - purkinje conduction , and permanent hbp at the distal hb ( distal to the site of the block / delay ) could restore physiological synchronous lv activation .
the hb pacing threshold remained excellent in our patient at the 6-month follow - up ; however , long - term follow - up is necessary .
theoretically , hbp is a more physiological treatment than bivp in patients with picm having preserved his - purkinje conduction .
further studies are needed to evaluate the long - term safety and efficacy of permanent hbp in patients with picm . in conclusion
this case shows that permanent hbp can be an effective alternative to bivp with significant improvements in heart failure symptoms and lvef .
right ventricular ( rv ) pacing has been reported to result in ventricular dyssynchrony , heart failure , and increased mortality . 
 pacing associated deterioration of left ventricular ( lv ) systolic function has been termed pacing - induced cardiomyopathy ( picm ) . while upgrading to biventricular pacing ( bivp ) is an effective therapy for picm , permanent his - bundle pacing ( hbp ) can be a physiological alternative to bivp . 
 we present a patient with picm who responded dramatically to permanent hbp .