Introduction

 
          
      We present a case of a rare complication of transvenous RV pacing causing iatrogenic interventricular septal perforation and LV pacing wherein a track was formed leading to frequent displacement of pacing wire into LV.
 

Case Presentation


  
    A 63 year old woman was referred for symptomatic complete heart block with heart rate of 30 bpm. A transvenous temporary pacing wire was inserted into right ventricle (RV) via the right internal jugular vein. ECG showed pacemaker spike with good capture but with right bundle branch block (BBB) pattern and right axis deviation (Fig.1). Chest X ray (CXR) showed the wire into left ventricle (LV) upper border and was posteriorly oriented on lateral film. A septal perforation with LV pacing was suspected and the wire was removed. A new temporary wire was inserted in our CCU under fluoroscopy through right femoral vein approach and placed into RV apex with ECG showing spike with left BBB pattern.

     The patient was asymptomatic but her Troponin T was elevated. After 2 days, she underwent coronary angiogram followed by single chamber permanent pacemaker implantation via the left subclavian approach with good position of pacing lead in RV apex confirmed on multiple fluoroscopy views and on lateral CXR.

     However, the following day after RV pacing insertion, the ECG again showed right BBB pattern pacing and the CXR and fluoroscopy showed high suspicion of lead in LV (Fig. 2&3). Transthoracic echocardiogram was inconclusive regarding the lead position and there was no pericardial effusion. A repeat ECG with lead placement lower than standard position showed persistent RBBB. A CT scan was performed which showed the pacing lead coursing from RV apex through the interventricular septum into LV apex (Fig.4&5). She was taken to the catheterization laboratory again, re-exploration was done and the pacing lead was re-positioned back into the RV free wall away from apex with good pacemaker position and parameters. The rest of her stay in the hospital was uneventful.

  
Discussion

 
Temporary transvenous cardiac pacing wires are usually inserted in an emergency situation. A recent review of temporary pacing incorporating 15 studies involving over 3700 patients from 1973 to 2004 showed a complication rate of 26.5% and the commonest complications were failure to secure venous access, failure to place the lead correctly, sepsis, puncture of arteries, lungs or myocardium and life-threatening arrhythmias. In this analysis, the incidence of cardiac perforation was 0.4%1. Acute complications after permanent pacemaker implantation are not uncommon, occurring in 4-7% of cases, and most frequently consist of lead displacement, traumatic pneumothorax, hemopneumothorax and pericardial tamponade2.

   One potential complication of lead positioning is cardiac perforation especially with active-fixation leads, which can cause pericardial effusion, cardiac tamponade, pneumothorax and death. Indicators of cardiac perforation include lead impedance changes, poor sensing or capture thresholds, diaphragmatic pacing, right BBB pacing pattern, and/or patient symptoms of chest pain and hypotension. Most perforations are extra cardiac with incidence of 0.4% to 1.2%3,4 and very rarely occur through the interventricular septum5.
Ventricular pacing usually involves placement of an electrode in the RV apex and manifests as left BBB morphology and left axis deviation on the surface ECG. This represents a right to left pattern of depolarization, from the site of electrode placement i.e., RV apex toward the LV, and suggests a delay in the depolarization of the left side on the surface ECG. Right BBB morphology implies a left-to-right depolarization pattern and suggests an incorrect location of the electrode that initiates the depolarization wave. The differential diagnosis of paced right BBB morphology includes inadvertent coronary sinus placement, inadvertent LV lead placement, or migration of the electrode into the LV (through a patent foramen ovale, atrial septal defect, or septal perforation). However, normally placed right ventricular lead in distal septum or apex (without entering LV) may sometimes produce right BBB type paced QRS complexes6.

Fig.1: Post-Temporary Pacing ECG showing pacemaker spike with RBBB pattern.

    Pacing electrodes inadvertently placed in the coronary sinus system can be left alone in asymptomatic patients, because the depolarization pattern may resemble physiologic patterns. However, the presence of pacing electrodes in the LV is associated with a 37% cerebral embolic rate, and full-dose anticoagulation is recommended7. Surgery is also considered for patients in whom the lead reached the LV as a result of ventricular septal perforation.

    Whether a right BBB pattern induced by ventricular pacing is the result of a malpositioned lead or an appropriately positioned right ventricular pacing lead has to be determined. The usual modalities to diagnose lead malposition are traditionally CXR/fluoroscopy along with echocardiography5 and CT scan8.
In our patient, the echocardiogram was inconclusive. CXR and fluoroscopy showed a posteriorly oriented pacing lead which may also be due to pacing lead in the coronary sinus. ECG performed one space below showed persistence of right BBB pattern in V1-2. Hence, CT scan was done to confirm that the pacing lead had indeed perforated the septum and was in the LV apex. The patient was then taken for re-positioning which was successfully done without need for surgical exploration.

    If imaging rules out lead malposition, then right BBB pattern during ventricular pacing may be due to what is called safe right BBB configuration. Coman et al.6 reported seven cases with right BBB pattern during permanent right ventricular pacing. The placement of leads V1-V2 one interspace lower than standard resulted in disappearance of right BBB morphology and inscription of QS or rS complexes in V1-V2. The exact mechanism for this is not known but theories are: portion of the interventricular septum which are anatomically RV may behave functionally and electrically as LV; the right BBB pattern could be the result of a combination of right ventricular activation delay due to severe disease of the right ventricular conduction system and early penetration of the electrical impulse into the left ventricular conduction system.

Fig.2: Post-Permanent Pacing lead in LV on AP view.

 

Fig.3: Post -Permanent Pacing lead in LV on Lateral view.

    To reduce this complication during temporary pacing, there are some precautions that need to be taken: 1) Caution should be exercised when utilizing a stiff temporary pacing wire and minimize the force applied when positioning the distal tip; 2) avoid excessive turns of the lead tip to minimize tissue damage and septal or wall penetration; and 3) to use a balloon-tipped temporary wires if available.¨

 

 

Fig.4: CT Chest showing pacemaker lead entering from RV into LV.

 

Fig.4: CT Chest showing pacemaker lead along the interventricular septum entering LV..

 

References:

1. McCann P. A Review of Temporary Cardiac Pacing Wires. Indian Pacing Electrophysiol J. 2007; 7(1): 40-49.

2. Tobin K, Stewart J, Westveer D, Frumin H. Acute complications of permanent pacemaker implantation: their financial implication and relation to volume and operator experience. Am J Cardiol 2000; 85:774-776.

3. Sivakumaran S, Irwin ME, Gulamhusein SS, Senaratne MP. Post pacemaker implant pericarditis: incidence and outcomes with active-fixation leads. Pacing Clin Electrophysiol 2002; 25:833-837.

4. Mahapatra S, Bybee KA, Espinosa RE, Sinak LJ, McGoon MD, Hayes, DL. Incidence and predictors of cardiac perforation after permanent pacemaker placement. Heart Rhythm 2005; 2:907-911.

5. James M, Townsend M, Aldington S. An unusual complication of transvenous temporary pacing. Heart 2003; 89:448.

6. Coman JA, Trohman RG. Incidence and electrocardiographic localization of safe right bundle branch block configurations during permanent ventricular pacing. Am J Cardiol 1995; 76: 781-784.

7. Van Gelder BM, Bracke FA, Oto A, et al. Diagnosis and management of inadvertently placed pacing and ICD leads in the left ventricle: a multicenter experience and review of the literature. Pacing Clin Electrophysiol. 2000; 23:877-883.

8. Sunil S, Joshua MC, Albert TC, Michael AA. Rib Perforation From a Right Ventricular Pacemaker Lead. Circulation 2007; 115:e391-e392.

THE WHEEL: 3500 BC                                     Mechanical Perfection                                                      Assyrian King Assurbanipal on his chariot,                                                                  (from 650-659 BC.)                                                                     The wheel has been around so long and is so ubiquitous that it can be difficult to see exactly why it is such a brilliant invention. In the end, it boils down to the way a wheel exploits the mathematical properties of a circle. The definition of a circle is a curve which keeps the same distance from a fixed point. So a wheel with an axle through its center allows you to keep the same height over the ground as you roll. And, as tangents touch circles at only one point, the rim of a wheel is guaranteed to make minimal contact with the thing most likely to slow it down: the ground [gravity]. Constant height, minimal contact – geometrical perfection turned into mechanical perfection. James Dyson, History of Great Inventions