a b s t r a c t

Temporary transvenous cardiac pacing is a life-saving procedure in an emergency. Transvenous cardiac pacing catheterization guided by intracavitary electrocardiogram (IC-ECG), instead of fluoroscope, is practical. Tips for controlling the orientation of the pacing catheter tip and utilizing IC-ECG to monitor the positions of electrodes make bedside temporary transvenous cardiac pacing catheter placement feasible and ‘visible’. The technique

discussed here is comparable to the operation under fluoroscopy,but without exposure to X-ray.

(C) 2019

Introduction

With a decline in the number of temporary transvenous cardiac pacing (TVCP) procedures clinically performed, the opportunity to learn and teach this skill is becoming increasingly scarce [1]. Nonetheless, it is a core emer- gency procedure [2]. TVCP involves placing a TVCP catheter into right side of the heart. Usually, the procedure is performed as followed: establishing central venous access; inserting introducer sheath; advancing TVCP cathe- ter in Venous system through the sheath; touching endocardium of right ventricle wall with TVCP catheter tip. Bedside atrial TVCP can only be rec- ommended for anti-tachycardia pacing because of its instability.

Extensively used bipolar TVCP catheter tip has two electrodes which are about 1 cm apart (Fig. 1). Distal electrode is negative (-) and active, proximal electrode is positive (+) and indifferent. For bedside TVCP catheter placement, 6 Fr in size non-floating catheter (Fig. 1) facilitates manipulation and not prone to dislocation if properly placed.

Establishing central venous access under ultrasound guidance is se- cure and has a low rate of complications [2]. Emergency cases with indi- cation for TVCP usually come with central venous distention which makes cannulation easy.

Catheterization technique of temporary transvenous cardiac pacing

Controlling the direction of catheter tip (Fig. 1) combined with mon- itoring electrodes of pacing catheter tip by intracavitary electrocardio- gram (IC-ECG) (Figs. 2, 3) makes bedside placement ‘visible’.

* Corresponding author at: Emergency Department, Hunan Provincial People’s Hospital, Medical School of Hunan Normal University, No. 61, Jiefang Road, Changsha, China.

E-mail address: [email protected] (M. Liu).

Ideally, there should be a 20-30? curve at the catheter tip [3]. If dif- ficulty is experienced in crossing the tricuspid valve, remove the cathe- ter and try fashioning a different curve [3]. Orifice of the tricuspid valve necessitates leftward of the catheter tip [3]. Controls tip orientation by turning the loops (Fig. 1). Therefore, TVCP catheter tip orientation can be manipulated accurately no matter which venous access is chosen, right jugular or right subclavian vein. The loops direction determines the catheter tip orientation. Inserted length of the catheter could help estimate the position of the catheter tip. In the meantime, IC-ECG pro- vides more precise position of catheter tip.

Pacing catheterization guided by IC-ECG has been practiced for half a century [4]. The appearance of a characteristic right ventricular endo- cardial complex recorded from the catheter tip is the most reliable guide to proper electrode placement [5]. Traditional IC-ECG guiding TVCP catheter insertion requires that the distal electrode from the end of the catheter be attached to any one of the precordial (V) leads on the ECG machine by an alligator clip or adapter. The adapter is supplied in some kit of TVCP catheter. Limbs electrodes are routinely connected. The V lead which connects distal tip of TVCP catheter is monitored (Fig. 2). As TVCP catheter approaches right atrium, the amplitude of P waves increases progressively; as TVCP catheter approaches the right ventricular wall, QRS amplitude increases progressively. When the cath- eter enters the ventricle, the QRS amplitude increases markedly. When the catheter tip touches the endocardial surface, ST-segment elevation (STEMI pattern) is seen. The highest QRS amplitude appears when tip

against the thickest ventricle wall which usually is the apex.

Jeffrey etc. suggested that TVCP catheter should be positioned against the ventricular wall to achieve b2 mV of ST elevation (Fig. 2F) [6]. Marked ST elevation (Fig. 2G) has been suggested as a characteristic sign of myocardial perforation [7].

https://doi.org/10.1016/j.ajem.2019.12.013

0735-6757/(C) 2019

820 M. Liu, X. Han / American Journal of Emergency Medicine 38 (2020) 819-822

Fig. 1. Tips for control catheter direction. Inserting TVCP catheter through right subclavian vein. The catheter tip orients to right at beginning. When catheter tip approaching right atrium, which could estimate by inserted length or/and monitor by IC-ECG, change the tip orientation to left by flipping the loops. The angle of loops turning is exactly the one of the catheter rotating.

Fig. 2. Typical intracavity-ECG. A, Superior vena cava; B, High right atrium to mid right atrium; C, Inferior vena cava; D, Crossing tricuspid valves; E, Right ventricle (Free); F, Right ventricle (Contact wall); G, Right ventricle (Against or continue touching wall). F & G, STEMI pattern.

M. Liu, X. Han / American Journal of Emergency Medicine 38 (2020) 819-822 821

Fig. 3. Bipolar intracavity-ECG avoid malposition of pacing catheter. A. Catheter tip is properly located. V(-) STEMI pattern, ST-segment elevate slightly (b2 mV) indicate distal tip contact properly with ventricle wall; V(+) QRS amplitude remarkedly high and QS inscribed indicate proximal tip nearby but not touch with ventricle wall. B. Catheter enters mid coronary sinus. C & D. Catheter tip against atrium wall. V(-) PR elevate is similar with STEMI pattern, V(+) no remarkedly high amplitude waves indicates catheter tip does not enter in ventricle. Synchronized V4 could help to distinguish P and QRS waves easily. E. Catheter tip entrapped in chordae tendineae. V(-) P waves vanish, QRS amplitude remarkedly increases, and then big R wave indicate catheter tip leaves atrium, enters ventricle and against ventricle wall. V(+) P waves vanish, QRS amplitude do not increases remarkedly indicate proximal electrode leaves atrium but not enters ventricle.

Three kinds of catheter malposition shown in Fig. 3B, C & D, E are rare but should be paid attention to. Catheter malposition in the coro- nary veins may not be recognized even under fluoroscope, however, IC-ECG provides a quick, reliable method to identify it [5]. By traditional single distal electrode IC-ECG [4], it may be difficult for the operator to identify malposition in those situations in Fig. 3C& D, E. ‘Current of in- jury’ can be recorded when electrode contacts with the atrial or ventric- ular endocardium, PR (atrial) elevation or STEMI pattern (ventricular). PR elevation could be mistaken as STEMI pattern (Fig. 3C & D). STEMI pattern of distal electrode IC-ECG only guarantees the tip to contact ven- tricle wall which includes entrapped in chordae tendineae (Fig. 3E).

We use both distal (-) and proximal (+) electrodes which can be attached to any two of the V leads, record as V(-) and V(+). Monitor- ing positions of the electrodes by V(-) and V(+) could provide more information about the tip position. Comparing the QRS amplitudes be- tween V(-) and V(+), when catheter tip enters right ventricle cham- ber: the case of V(-) N V(+) infers tip toward apex ventricle wall (Fig. 3A); conversely, the case of V(-) b V(+) indicates tip directs to outflow tract.

Monitoring both V(-) and V(+) helps distinguish PR elevation (Fig. 3C & D) to STEMI pattern and identify catheter tip entrapped in chordae tendineae (Fig. 3E).

After IC-ECG guiding placement which assures TVCP catheter tip contacting properly with the ventricle wall, setting the pacing parame- ters would be simple. Parameters include heart rate, sense and output. Default sense setting as 2 mV usually does not need to adjust. Premier cause of sensing and pacing malfunction is catheter dislocation. It can be identified by IC-ECG if Temporary pacemaker could disconnect for a while. Pacing threshold usually is b1 mA [8], default output setting as 3-4 mA would be appropriate, whereas a few pathological situations, such as myocarditis, pacing threshold may be N5 mA.

Technique summary

After establishing central venous access and placing introducer sheath, bedside TVCP catheterization can be practiced with following skills: furnishing TVCP catheter tip an appropriate curve, coiling the

catheter as 2-3 loops, and manipulating loops to control catheter tip di- rection; estimating catheter tip position according to inserted length and precisely locating catheter tip by bipolar IC-ECG monitoring.

Discussion

The use of fluoroscopy to guide TVCP catheterization is desirable from a technical point of view, but it may not be practical or available in the acute care setting. 5 Fr flexible, balloon flotation catheters are most commonly used in emergency cases [8,9]. Guidance was attained by using Continuous ECG monitoring or by IC-ECG of a distal lead [8,9]. Benefit of balloon flotation catheter is that forward blood flow guides the balloon through the venous system into the right ventricle. Then the catheter tip is required to be placed in a stable position, the right ventricle apex. But forward blood flow tends to guide balloon catheter tip to the Right ventricular outflow tract. Though balloon flotation cath- eters may help to reduce procedure time and improve positioning under fluoroscopic guidance [10], Nicole et al. reported: without fluoro- scopic visualization, only 44% (n = 39) of catheters tips were in the apex of the right ventricle [9]. 5 Fr balloon flotation catheter tends to be curled, and too flexible to be manipulated as 6 Fr non-floating catheter.

With technique tips discussed above, 6 Fr non-floating catheter is practical for bedside insertion. For the patient in cardiac arrest, balloon flotation catheter carries no benefit. And blind insertion of a 6 Fr non- floating catheter by direction control tips described in Fig. 1 would be the best choice. Traditional single distal electrode IC-ECG indicates the lead location [4], included in ventricle or contacting ventricle wall (Fig. 2), but it cannot distinguish right ventricular apex from elsewhere in the right ventricle. The bipolar IC-ECG provides adequate information about the tip position (Figs. 2, 3), which is comparable to Fluoroscopic visualization. With no exposure to X-ray, consequently it may encour- age more physicians to learn this skill.

Author contribution statement Meng Liu: Conceptualization and draft writing. Xiaotong Han: Supervision.

Declaration of interest“>822 M. Liu, X. Han / American Journal of Emergency Medicine 38 (2020) 819-822

Declaration of interest

None.

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