Page 21 - Delaware Medical Journal August 2015
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SCIENTIFIC ARTICLE
of RV pacing dependence documented
on repeated visits into Group 1, which included patients with high degree of
RV pacing, (RV pacing >40 percent of the time), and Group 2, which included patients with low frequency of RV pacing (RV pacing <40 percent of the time).
All right ventricular leads were implanted apically. Patients with single lead were
all programmed to be in VVI-R mode (ventricular pacing, ventricular sensing, inhibition response and rate-adaptive). Patients with dual lead were set up to be in DDD-R mode (dual-chamber sensed and paced, rate-modulated) with algorithm to prevent pacemaker-mediated tachycardia (PMT). Back-up rate varied from 50- 60 beats per minute (BPM) for patients with known
or who are expected to develop bradycardia. The difference was related to operator and patients’ factors. Back-up rate in primary prevention ICD patients without associated bradycardia (20 patients) was 40 BPM.
A complete echocardiography evaluation was followed for both ICD and PPM groups, including the measurement of
the LV function and the evaluation of Atrioventricular (AV) valves. Grading the severity of both mitral regurgitation (MR) and tricuspid regurgitation (TR) was done according to the recommendations of the American Society of Echocardiography.7 The regurgitation was graded as: Absent, Mild, Moderate, or Severe.
The intensity of MR was assessed using either of the following measurements: the doppler vena contracta width (mild if vena contracta width <3 mm, moderate 3-7 and severe if > 7 mm); color jet area (mild if jet area <4 cm2, moderate 4-10 cm2 and severe if jet area >10 cm2); regurgitant volume (mild if regurgitant volume <30 mL, moderate if 30–60 mL, or severe
if >60 mL); and/or regurgitant fraction
FIGURE 1
Impact of Right Ventricle Pacing on LV Function.
FIGURE 2
Impact of Right Ventricle Pacing on Pulmonary Hypertension.
(mild if regurgitant fraction <30 percent, moderate if 30-50 percent, or severe if >50 percent).7 In case of inconsistency between these measurements, the doppler vena doppler vena contracta width (mild if vena contracta width <3 mm, moderate 3-7 and severe if > 7 mm) and color jet area (mild if vena contracta width <5 cm2, moderate 5-10 cm2 and severe if >10 cm2).7 The RV systolic pressure (RVSP) or pulmonary artery systolic pressure (PSAP) was measured using the TR jet. The most important factor in determining the systolic pressure is
the method of right atrial (RA) pressure measurement. The RA pressure was measured considering the inferior vena cava
size and respiratory variation. RA pressure was considered 5 mm if the inferior vena cava is normal sized. For dilated inferior vena cava with normal respiratory variation, an assumed constant of 10 mm was employed. For a dilated inferior vena cava without respiratory variation, an assumed constant of 15 mm was used.7
Left Ventricle End Systolic Dimension (LVESD) and Left Ventricle End Diastolic Dimension (LVEDD) are measured at the level of the LV minor axis, approximately parasternal long-axis acoustic window.8 Volumetric Biplane Simpsons’ method was used for evaluation of left ventricle ejection fraction (LVEF).8
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