Open Journal of Internal Medicine, 2011, 1, 1-3 OJIM
doi:10.4236/ojim.2011.11001 Published Online June 2011 (http://www.SciRP.org/journal/ojim/).
Published Online June 2011 in SciRes. http://www.scirp.org/journal/OJIM
Late rising right ventricular pacing lead threshold four years
after implantation of a dual chamber pacemaker
H. Zaky*, H. El Zein, A. Al-Mulla
Dubai hospital, Dubai, UAE.
Received 7 May 2011; revised 1 June 2011, accepted 13 June 2011.
ABSTRACT
Late rising in pacing threshold is an uncommon
complication of permanent pacing. Treatment with
high dose systemic steroid could spare the patient
another procedure. We report a case of late rising
pacing threshold that responded to high dose sys-
temic steroid which lowered the pacing threshold to
one volt, then r ose again to around 2 volts.
Keywords: Late Rising Pacing Threshold
1. INTRODUCTION
Late rising pacing threshold is an uncommon complica-
tion of pacemaker implantation. The use of systemic
steroids to treat high pacing threshold has been sug-
gested, and large doses of systemic steroids have been
reported to result in decrement in pacing thresholds.
However, when steroids are discontinued, the thresholds
generally increase again [1,2].
2. HISTORY
78 year old lady with a long-standing history of hyper-
tension on regular treatment presented with a 20 day
history of exertional dyspnoea. She had no history of
chest pains, palpitations, dizziness or syncope. She had
no orthopnoea or paroxysmal nocturnal dyspnoea.
Clinical examination revealed: BP 188/57, pulse 35
beats per minute, normal audible heart sounds, no added
heart sounds and no murmurs, clear chest, and bilateral
carotid bruits. ECG: showed sinus rhythm with second
degree heart block mobitz type 2 (2:1 block), Labs: nor-
mal cardiac markers, normal renal function with no elec-
trolyte abnormalities. Echocardiography showed fair LV
function (ejection fraction 50%), LV diastolic dysfunc-
tion grade 1, mild mitral regurgitation, mild aortic regur-
gitation, moderate tricuspid regurgitation, pulmonary
artery pressure 25 mmhg, no pericardial effusion, no
regional wall motion abnormalities. She underwent coro-
nary & carotid angiography which was normal. A dual
chamber permanent pacemaker was inserted on 01-
10-2005 with RV lead pacing threshold of < 0.5 V at the
time of implant. Both leads were steroid eluting, active
fixation, and continued to have regular follow up in the
pacemaker clinic.
On 23-07-2009 she presented with dizziness and a
heart rate between 35 - 40 bpm with a wide complex
escape rhythm and loss of pacemaker capture. The RV
lead capture threshold was found to be high both in bi-
polar and unipolar configuration (3.75 V/0.4 MS) with
acceptable sensitivity and impedance (sensed R wave >
12.5 mv, and impedance 465 Ώ). The battery was not
depleted; there were no metabolic derangements, elec-
trolyte disturbances or drug effects. A myocardial perfu-
sion scan showed no evidence of ischemia or scar that
might explain the rising pacing threshold. Chest X ray
did not show any dislodgment. The possibilities were
either microdislodgement or exit block; so we increased
the output to maximum with good capture and we
thought of implanting another RV lead. However, we
tried systemic steroids first, and started high dose pred-
nisolone 60 mg od for 4weeks at the end of which her
RV threshold dropped to 2.2 V/0.4 MS. We then started
tapering of the prednisolone over another 4 weeks at the
end of which her RV threshold dropped to 1 V/0.4 MS.
On follow up (1-11-2009), the RV threshold was found
to have increased to 2.2 V/0.4 MS, but had stabilized,
when she was last seen on 15-03-2011 her RV threshold
was found to be 2 V/0.4 MS.
3. DISCUSSION
In this case, our use of systemic steroids prevented any
interventional implantation of a new right ventricular
lead, and this was in line with what other authors have
reported [1,3,4]. we gave steroids for 4 weeks and ta-
pered over another 4 weeks in comparison to nagatomo
et al. who gave steroids for 5 months with similar results,
also Ferraro et al. used azathioprime to decrease the dose

H. Zaky et al. / Open Journal of Internal Medicine 1 (2011) 1-3 2
0
0.5
1
1.5
2
2.5
3
3.5
4
4.5
Thres ho ld(volt)/0.4ms
prednisolone
60m g started
prednisolonestopped
tapperin g
prednisolone
volt
Figure 1. This graph shows the changes in right ventricular pacing threshold over
time and decrease in threshold in response to steroids and the rise after discontinua-
tion of the steroids.
Figure 2. Showing intermittent capture of pacing before starting therapy.
of steroids to keep the pacing thresholds acceptable [5].
There are only few case reports and anecdotes of the
use of steroids in late rising pacemaker lead thresholds.
Despite the lack of randomized clinical trials to sup-
port this pharmacological intervention, the use of sys-
temic steroids was associated with the prevention of an
intervention and decreased her threshold to 1 V/0.4
MS which rose to two volts after withdrawal of the

H. Zaky et al. / Open Journal of Internal Medicine 1 (2011) 1-3 3
steroids. This is consistent with other reports. [1-5].
4. CONCLUSIONS
In cases where pacemaker leads exhibit late rising
thresholds, it is worth trying systemic steroids prior to
subjecting patients to further intervention.
REFERENCES
[1] Beanland, D.S., Akyureckli, Y., Keon, W.J. (1979) Pred-
nisolone in the management of exit block. Proceedings of
the 6th World Symposium on Cardiac Pacing, Montreal,
2-5 October 1979, 18-3.
[2] Risby, O., Meibom, J., Nyboe, I., Schuller, H. (1981) The
influence of prednisolone on pacemaker threshold (ab-
stract). Pacing Clinical Electrophysiol, 4, A-68.
[3] Nagatomo, Y., Ogawa, T., et al. (1989) Pacing failure due
to markedly increased stimulation threshold two years
after implantation: Successful management with oral
prednisolone: A case report. Pacing and Clinical Elec-
trophysiology, 12, 1034-1037.
doi:10.1111/j.1540-8159.1989.tb01922.x
[4] Preston, T.A., Judge, R.D., Lucchesi, B.R., et al. (1966)
Myocardial threshold in patients in patients with artificial
pacemakers. American Journal of Cardiology, 18, 83-89.
doi:10.1016/0002-9149(66)90199-8
[5] Ferraro, A., Sabena Masi, A., Mazza, A. (2009) Increased
stimulation threshold in a patient with autoimmune dis-
ease: Successful management with oral prednisolone and
azathioprine. The European Journal of Pacing, 11,
527-529.