DEVICES
Proximity of Pacemaker and Implantable Cardioverter-Defibrillator Leads to Coronary Arteries as Assessed by Cardiac Computed Tomography BENJAMIN J. PANG, M.B.B.S., B.SC.,*,† SUBODH B. JOSHI, M.B.B.S, M.P.H.,* ELAINE H. LUI, M.B.B.S.,‡ MARK A. TACEY, B.SC.,§ JEFF ALISON, M.B.B.S.,¶,** SUJITH K. SENEVIRATNE, M.B.B.S.,¶,** JAMES D. CAMERON, M.B.B.S., M.D.,¶,** and HARRY G. MOND, M.D.*,† From the *Department of Cardiology, Royal Melbourne Hospital, Parkville, Victoria, Australia; †Department of Medicine, University of Melbourne, Victoria, Australia; ‡Department of Radiology, Royal Melbourne Hospital & University of Melbourne, Victoria, Australia; §Melbourne EpiCentre, University of Melbourne, Victoria, Australia; ¶Monash Cardiovascular Research Centre, MonashHEART, Melbourne, Australia; and **Southern Clinical School, Monash University, Melbourne, Australia
Introduction: There have been rare case reports of damage to adjacent coronary arteries by screw-in pacemaker and implantable cardioverter-defibrillator (ICD) leads. Our aim was to assess the proximity of pacemaker and ICD leads to the major coronary anatomy using cardiac computed tomography (CT). Methods: Cardiac CT images were retrospectively analyzed to assess the spatial relationship of device lead tips to the major coronary anatomy. Results: Fifty-two right ventricular (RV) leads (17 apical, 35 nonapical) and 35 right atrial (RA) leads were assessed. Leads on the RV antero-septal junction (20 of 52) were close (median 4.7 mm) to, and orientated toward, the left anterior descending (LAD) coronary artery. RA leads in the anterior (26 of 35) and lateral (seven of 35) walls of the RA appendage were not close to (16.9 ± 7.7 mm and 18.9 ± 12.4 mm, respectively) and directed away from the right coronary artery. However, an RA lead adjacent to the superior border of the tricuspid valve was 4.3 mm from the right coronary artery and an RA lead on the medial wall of the RA appendage was 1.6 mm away from the aorta. An RV pacemaker lead in the lateral wall of the RV inlet was 3.4 mm from the right coronary artery. Conclusions: In our cohort, a majority of RV leads were on the antero-septal junction and close to the overlying LAD coronary artery. RA leads adjacent to the tricuspid valve or on the medial RA appendage were in close proximity to the right coronary artery and aorta, respectively. (PACE 2014; 37:717–723) pacing lead implantation, coronary arteries, CT Introduction Active-fixation leads attach via helical screws that tunnel into atrial or ventricular myocardium. Concerns have been raised about the close proximity of active-fixation lead tips to the coronary arteries.1 There have been rare case reports in the pacing literature of damage to coronary arteries by active-fixation leads. A screw-in pacing lead2 in the right ventricular (RV) outflow tract and an implantable cardioverter-defibrillator (ICD) lead3 Funding sources: None to declare. Address for reprints: Harry Mond, M.D., Department of Cardiology, Royal Melbourne Hospital, Grattan Street, Parkville, Victoria, Australia 3050. Fax: 61-3-9347-2808; e-mail: [email protected] Received April 1, 2013; revised October 15, 2013; accepted October 20, 2013. doi: 10.1111/pace.12330
in the RV apex have caused acute occlusion of the left anterior descending (LAD) coronary artery. A perforated right atrial (RA) lead produced a communicating pseudo-aneurysm with the right coronary artery.4 However, in large case series in the pacing literature, there have been no reports of damage to coronary arteries.5,6 Pacemakers are implanted under fluoroscopy, an imaging modality that only allows limited visualization of cardiac structures apart from the cardiac silhouette. We have previously reported cases where the close proximity of pacing leads in nonapical RV regions to the coronary arteries was appreciated with fluoroscopy and coronary angiography.7 Cardiac computed tomography (CT) offers the opportunity to examine the relationship between leads and coronary arteries. Using the same cardiac CT images that we have used in previous analyses for validation of RV ventricular lead position8 and lead perforation,9 we assessed
©2013 Wiley Periodicals, Inc. PACE, Vol. 37
June 2014
717
PANG, ET AL.
the proximity of the RA and RV pacing and ICD lead tips to the major coronary arteries. Methods Patients who had a cardiac CT for standard clinical indications following device implantation were retrospectively identified from an electronic database at two institutions (MonashHEART and the Royal Melbourne Hospital). At MonashHEART (Monash Medical Centre), patients were imaged with a single-source Toshiba Aquilion One (Toshiba Medical Systems, Tokyo, Japan) 320 multislice multidetector array CT scanner between 2008 and 2012 using a standard coronary CT angiography protocol. The images were acquired with prospective electrocardiogram (ECG) gating with a phase window of 70–80%, an image matrix of 512 × 512, after administration of 75 mL of Omnipaque 350 at 6 mL/s, followed by 50 mL of saline. An initial reconstruction at the 75% phase was performed. If cardiac motion was noted, additional phases without motion were produced. Overlapping reconstructions of 0.5-mm slices every 0.25 mm were reconstructed in soft kernels. At the Royal Melbourne Hospital, a dual-source 64-slice CT scanner (Somatom Definition, Siemens, Erlangen, Germany) was used. The images were acquired with prospective ECG gating at 70% phase, with a 512 × 512 image matrix and slice thickness of 0.65 mm after injection of 70-mL Visipaque (iodixanol) 270 at 5 mL/s, followed by a 30/70 mix of 15-mL Visipaque 270 and 35 mL normal saline at 5 mL/s before a normal saline flush of 40 mL at 5 mL/s. The tube voltage used was between 100 kV and 120 kV depending on patient size. Reconstructions were performed at 0.75-mm slice thickness and 0.5-mm intervals using B26 (soft) and B46 (hard) kernels. Analysis was conducted with the OSIRIX version 4.2.1 open source software package (OsiriX Foundation, Geneva, Switzerland) DICOM viewer.10 Cardiac CT Image Evaluation All reconstructed cardiac CT images were anonymized and reviewed independently by a cardiologist with subspecialty interest in cardiac CT (SJ) and a cardiologist (BP) trained in cardiac CT. Standard axial images and oblique longand short-axis multiplanar reformations were evaluated. Bloom artifact surrounding the lead tip was minimized by optimizing the window level and width (approximately 3,500 and 10,000 HU, respectively) while still allowing identification of the coronary arteries. The minimum distance between the outer edge of the right atrial (RA) and RV pacemaker lead tip and the nearest edge
718
Figure 1. CT coronal three-dimensional reconstruction. The RV pacing lead is on the anterior-septal junction and points toward the overlying left anterior descending (LAD) coronary artery. The RA pacing lead is positioned in the middle vertical level of the RA and directed toward, and is only 4.3 mm away (the measurement was from the multiplanar reformatted cardiac CT image) from the right coronary artery (RCA). Ao = aorta; CT = computed tomography; LV = left ventricular; RA = right atrial; RV = right ventricular; RVOT = RV outflow tract.
of the contrast-enhancing lumen of the right and LAD coronary arteries, respectively, were then measured from the reformatted CT images using OSIRIX software. Anatomy of the Coronary Arteries The left main coronary artery passes in the coronary groove between the left atrial appendage and RV outflow tract or pulmonary trunk before dividing into the LAD and left circumflex coronary artery. The LAD coronary artery runs in the epicardial space between the left ventricle and RV in the anterior interventricular groove, directly overlying the RV antero-septal junction (Fig. 1). The LAD coronary artery sends perforating anterior interventricular septal branches into the interventricular septum. The right coronary artery is partly covered by the RA appendage as it travels in the atrioventricular groove. The posterior descending artery arises from the right coronary artery (or in 15% of cases the left circumflex) and supplies posterior perforating interventricular septal branches. Pacemaker Lead Position RV lead position was defined in the longand short-axis views. From the four-chamber view, the RV lead position was classified in the (A) basal third “RV outflow tract,” (B) middle third “middle RV,” or (C) apical third “RV apex” (Fig. 2).
June 2014
PACE, Vol. 37
PACEMAKER LEAD PROXIMITY TO CORONARY ARTERIES
Middle RV
RVOT
Lateral
RV Apex
Anterior
RAA
R A
RA
CT
LV
LA
RV
Ao Septum
LA
Septum
Superior
LV Inferior
Middle Infero-septal Junction
RA
Figure 2. Determination of lead location in CT long and short axis. (Top) CT four-chamber long-axis view, classifying lead position into the RV outflow tract (RVOT), middle RV, or RV apex. (Bottom) CT short-axis view RV pacing lead position: septum, anterior RV wall, antero-septal junction, infero-septal junction. LA = left atrial. Other abbreviations as in Figure 1.
Leads in the middle RV and RV outflow tracts were classified as RV nonapical leads. The RV antero-septal and infero-septal junctions and different walls of the RV in the CT short-axis view were defined as shown in Figure 2. The RA appendage comprises a substantial portion of the RA and is separated from the posteriorly located smooth-walled sinus venosus by the crista terminalis (Fig. 3). The vestibule forms a smooth muscular rim surrounding the tricuspid valve and the interatrial septum is the shared wall between the RA and left atrium.11 RA lead position was classified in the CT axial view as being on the anterior, lateral, or medial wall of the RA appendage, or septal RA wall. The medial wall of the RA appendage abuts the aorta (Fig. 3).11 In the vertical plane, the region above a horizontal
PACE, Vol. 37
LV
Antero-septal Junction
Anterior
Lateral
RV
SV LV
LA
Medial
Inferior
Tv RV
Figure 3. (Top) RA lead position in the axial plane; anterior, lateral, and medial walls of the RA appendage (RAA), and the RA septal wall. The crista terminalis (CT) separates the RA appendage from the sinus venosus. (Bottom) Vertical level of the RA lead. The upper border of the inferior third of the RA is marked by the upper border of the tricuspid valve (Tv). Ao = aorta. Other abbreviations as in Figures 1 and 2.
line at the superior border of the tricuspid valve was divided in half into the superior and middle levels. The region below the level of the superior border of the tricuspid valve was classified as the inferior vertical level of the RA (Fig. 3). Passive fixation pacing leads attach by hooking tines onto trabeculated muscle and are usually limited to the RA appendage and RV apex. Active-fixation leads are able to attach to additional locations in the heart. However, the 1.6–2-mm active helical screw in pacemaker and ICD leads presents potential risks of perforation
June 2014
719
PANG, ET AL.
Table I. Baseline Patient Characteristics Mean Age (Years) Male Ischemic heart disease Previous myocardial infarction Atrial fibrillation Diabetes Heart failure Left ventricular ejection fraction (%)
73 ± 12 22 (43%) 17 (73%) 4 (8%) 20 (39%) 15 (29%) 8 (16%) 52 ± 14%
and iatrogenic damage to coronary arteries or the aorta. Pacemaker Implantation RV nonapical leads were implanted using a shaped stylet with a large primary and smaller distal secondary curve as described by Mond12 A straight or slightly curved stylet was used to implant RV apical leads. RA leads were implanted using a curved J stylet.13 This retrospective analysis was approved by the Monash University Institutional Ethics Committee as a quality assurance project (# 12241Q). Statistical Analysis Comparisons of means were made using the Student’s t-test where the data were normally distributed. For data that were not normally distributed, the Mann-Whitney test or KruskalWallis test as applicable was used. Fisher’s exact test was used to test for significance between categorical variables when there were fewer than five samples within each group. A two-tailed P-value of
Proximity of Pacemaker and Implantable Cardioverter-Defibrillator Leads to Coronary Arteries as Assessed by Cardiac Computed Tomography BENJAMIN J. PANG, M.B.B.S., B.SC.,*,† SUBODH B. JOSHI, M.B.B.S, M.P.H.,* ELAINE H. LUI, M.B.B.S.,‡ MARK A. TACEY, B.SC.,§ JEFF ALISON, M.B.B.S.,¶,** SUJITH K. SENEVIRATNE, M.B.B.S.,¶,** JAMES D. CAMERON, M.B.B.S., M.D.,¶,** and HARRY G. MOND, M.D.*,† From the *Department of Cardiology, Royal Melbourne Hospital, Parkville, Victoria, Australia; †Department of Medicine, University of Melbourne, Victoria, Australia; ‡Department of Radiology, Royal Melbourne Hospital & University of Melbourne, Victoria, Australia; §Melbourne EpiCentre, University of Melbourne, Victoria, Australia; ¶Monash Cardiovascular Research Centre, MonashHEART, Melbourne, Australia; and **Southern Clinical School, Monash University, Melbourne, Australia
Introduction: There have been rare case reports of damage to adjacent coronary arteries by screw-in pacemaker and implantable cardioverter-defibrillator (ICD) leads. Our aim was to assess the proximity of pacemaker and ICD leads to the major coronary anatomy using cardiac computed tomography (CT). Methods: Cardiac CT images were retrospectively analyzed to assess the spatial relationship of device lead tips to the major coronary anatomy. Results: Fifty-two right ventricular (RV) leads (17 apical, 35 nonapical) and 35 right atrial (RA) leads were assessed. Leads on the RV antero-septal junction (20 of 52) were close (median 4.7 mm) to, and orientated toward, the left anterior descending (LAD) coronary artery. RA leads in the anterior (26 of 35) and lateral (seven of 35) walls of the RA appendage were not close to (16.9 ± 7.7 mm and 18.9 ± 12.4 mm, respectively) and directed away from the right coronary artery. However, an RA lead adjacent to the superior border of the tricuspid valve was 4.3 mm from the right coronary artery and an RA lead on the medial wall of the RA appendage was 1.6 mm away from the aorta. An RV pacemaker lead in the lateral wall of the RV inlet was 3.4 mm from the right coronary artery. Conclusions: In our cohort, a majority of RV leads were on the antero-septal junction and close to the overlying LAD coronary artery. RA leads adjacent to the tricuspid valve or on the medial RA appendage were in close proximity to the right coronary artery and aorta, respectively. (PACE 2014; 37:717–723) pacing lead implantation, coronary arteries, CT Introduction Active-fixation leads attach via helical screws that tunnel into atrial or ventricular myocardium. Concerns have been raised about the close proximity of active-fixation lead tips to the coronary arteries.1 There have been rare case reports in the pacing literature of damage to coronary arteries by active-fixation leads. A screw-in pacing lead2 in the right ventricular (RV) outflow tract and an implantable cardioverter-defibrillator (ICD) lead3 Funding sources: None to declare. Address for reprints: Harry Mond, M.D., Department of Cardiology, Royal Melbourne Hospital, Grattan Street, Parkville, Victoria, Australia 3050. Fax: 61-3-9347-2808; e-mail: [email protected] Received April 1, 2013; revised October 15, 2013; accepted October 20, 2013. doi: 10.1111/pace.12330
in the RV apex have caused acute occlusion of the left anterior descending (LAD) coronary artery. A perforated right atrial (RA) lead produced a communicating pseudo-aneurysm with the right coronary artery.4 However, in large case series in the pacing literature, there have been no reports of damage to coronary arteries.5,6 Pacemakers are implanted under fluoroscopy, an imaging modality that only allows limited visualization of cardiac structures apart from the cardiac silhouette. We have previously reported cases where the close proximity of pacing leads in nonapical RV regions to the coronary arteries was appreciated with fluoroscopy and coronary angiography.7 Cardiac computed tomography (CT) offers the opportunity to examine the relationship between leads and coronary arteries. Using the same cardiac CT images that we have used in previous analyses for validation of RV ventricular lead position8 and lead perforation,9 we assessed
©2013 Wiley Periodicals, Inc. PACE, Vol. 37
June 2014
717
PANG, ET AL.
the proximity of the RA and RV pacing and ICD lead tips to the major coronary arteries. Methods Patients who had a cardiac CT for standard clinical indications following device implantation were retrospectively identified from an electronic database at two institutions (MonashHEART and the Royal Melbourne Hospital). At MonashHEART (Monash Medical Centre), patients were imaged with a single-source Toshiba Aquilion One (Toshiba Medical Systems, Tokyo, Japan) 320 multislice multidetector array CT scanner between 2008 and 2012 using a standard coronary CT angiography protocol. The images were acquired with prospective electrocardiogram (ECG) gating with a phase window of 70–80%, an image matrix of 512 × 512, after administration of 75 mL of Omnipaque 350 at 6 mL/s, followed by 50 mL of saline. An initial reconstruction at the 75% phase was performed. If cardiac motion was noted, additional phases without motion were produced. Overlapping reconstructions of 0.5-mm slices every 0.25 mm were reconstructed in soft kernels. At the Royal Melbourne Hospital, a dual-source 64-slice CT scanner (Somatom Definition, Siemens, Erlangen, Germany) was used. The images were acquired with prospective ECG gating at 70% phase, with a 512 × 512 image matrix and slice thickness of 0.65 mm after injection of 70-mL Visipaque (iodixanol) 270 at 5 mL/s, followed by a 30/70 mix of 15-mL Visipaque 270 and 35 mL normal saline at 5 mL/s before a normal saline flush of 40 mL at 5 mL/s. The tube voltage used was between 100 kV and 120 kV depending on patient size. Reconstructions were performed at 0.75-mm slice thickness and 0.5-mm intervals using B26 (soft) and B46 (hard) kernels. Analysis was conducted with the OSIRIX version 4.2.1 open source software package (OsiriX Foundation, Geneva, Switzerland) DICOM viewer.10 Cardiac CT Image Evaluation All reconstructed cardiac CT images were anonymized and reviewed independently by a cardiologist with subspecialty interest in cardiac CT (SJ) and a cardiologist (BP) trained in cardiac CT. Standard axial images and oblique longand short-axis multiplanar reformations were evaluated. Bloom artifact surrounding the lead tip was minimized by optimizing the window level and width (approximately 3,500 and 10,000 HU, respectively) while still allowing identification of the coronary arteries. The minimum distance between the outer edge of the right atrial (RA) and RV pacemaker lead tip and the nearest edge
718
Figure 1. CT coronal three-dimensional reconstruction. The RV pacing lead is on the anterior-septal junction and points toward the overlying left anterior descending (LAD) coronary artery. The RA pacing lead is positioned in the middle vertical level of the RA and directed toward, and is only 4.3 mm away (the measurement was from the multiplanar reformatted cardiac CT image) from the right coronary artery (RCA). Ao = aorta; CT = computed tomography; LV = left ventricular; RA = right atrial; RV = right ventricular; RVOT = RV outflow tract.
of the contrast-enhancing lumen of the right and LAD coronary arteries, respectively, were then measured from the reformatted CT images using OSIRIX software. Anatomy of the Coronary Arteries The left main coronary artery passes in the coronary groove between the left atrial appendage and RV outflow tract or pulmonary trunk before dividing into the LAD and left circumflex coronary artery. The LAD coronary artery runs in the epicardial space between the left ventricle and RV in the anterior interventricular groove, directly overlying the RV antero-septal junction (Fig. 1). The LAD coronary artery sends perforating anterior interventricular septal branches into the interventricular septum. The right coronary artery is partly covered by the RA appendage as it travels in the atrioventricular groove. The posterior descending artery arises from the right coronary artery (or in 15% of cases the left circumflex) and supplies posterior perforating interventricular septal branches. Pacemaker Lead Position RV lead position was defined in the longand short-axis views. From the four-chamber view, the RV lead position was classified in the (A) basal third “RV outflow tract,” (B) middle third “middle RV,” or (C) apical third “RV apex” (Fig. 2).
June 2014
PACE, Vol. 37
PACEMAKER LEAD PROXIMITY TO CORONARY ARTERIES
Middle RV
RVOT
Lateral
RV Apex
Anterior
RAA
R A
RA
CT
LV
LA
RV
Ao Septum
LA
Septum
Superior
LV Inferior
Middle Infero-septal Junction
RA
Figure 2. Determination of lead location in CT long and short axis. (Top) CT four-chamber long-axis view, classifying lead position into the RV outflow tract (RVOT), middle RV, or RV apex. (Bottom) CT short-axis view RV pacing lead position: septum, anterior RV wall, antero-septal junction, infero-septal junction. LA = left atrial. Other abbreviations as in Figure 1.
Leads in the middle RV and RV outflow tracts were classified as RV nonapical leads. The RV antero-septal and infero-septal junctions and different walls of the RV in the CT short-axis view were defined as shown in Figure 2. The RA appendage comprises a substantial portion of the RA and is separated from the posteriorly located smooth-walled sinus venosus by the crista terminalis (Fig. 3). The vestibule forms a smooth muscular rim surrounding the tricuspid valve and the interatrial septum is the shared wall between the RA and left atrium.11 RA lead position was classified in the CT axial view as being on the anterior, lateral, or medial wall of the RA appendage, or septal RA wall. The medial wall of the RA appendage abuts the aorta (Fig. 3).11 In the vertical plane, the region above a horizontal
PACE, Vol. 37
LV
Antero-septal Junction
Anterior
Lateral
RV
SV LV
LA
Medial
Inferior
Tv RV
Figure 3. (Top) RA lead position in the axial plane; anterior, lateral, and medial walls of the RA appendage (RAA), and the RA septal wall. The crista terminalis (CT) separates the RA appendage from the sinus venosus. (Bottom) Vertical level of the RA lead. The upper border of the inferior third of the RA is marked by the upper border of the tricuspid valve (Tv). Ao = aorta. Other abbreviations as in Figures 1 and 2.
line at the superior border of the tricuspid valve was divided in half into the superior and middle levels. The region below the level of the superior border of the tricuspid valve was classified as the inferior vertical level of the RA (Fig. 3). Passive fixation pacing leads attach by hooking tines onto trabeculated muscle and are usually limited to the RA appendage and RV apex. Active-fixation leads are able to attach to additional locations in the heart. However, the 1.6–2-mm active helical screw in pacemaker and ICD leads presents potential risks of perforation
June 2014
719
PANG, ET AL.
Table I. Baseline Patient Characteristics Mean Age (Years) Male Ischemic heart disease Previous myocardial infarction Atrial fibrillation Diabetes Heart failure Left ventricular ejection fraction (%)
73 ± 12 22 (43%) 17 (73%) 4 (8%) 20 (39%) 15 (29%) 8 (16%) 52 ± 14%
and iatrogenic damage to coronary arteries or the aorta. Pacemaker Implantation RV nonapical leads were implanted using a shaped stylet with a large primary and smaller distal secondary curve as described by Mond12 A straight or slightly curved stylet was used to implant RV apical leads. RA leads were implanted using a curved J stylet.13 This retrospective analysis was approved by the Monash University Institutional Ethics Committee as a quality assurance project (# 12241Q). Statistical Analysis Comparisons of means were made using the Student’s t-test where the data were normally distributed. For data that were not normally distributed, the Mann-Whitney test or KruskalWallis test as applicable was used. Fisher’s exact test was used to test for significance between categorical variables when there were fewer than five samples within each group. A two-tailed P-value of
