Emergency pacing during cardiac catheterization: It is all there already

It has been known for almost 20 years that there is no need to seek hurriedly the femoral vein and navigate a pacemaker lead to the right ventricle when severe bradycardia or asystole occurs during cardiac catheterization. And then again it has not. The preceding report reminds us of the fact that the coronary guidewire provides a handy pacemaker lead when need for rhythm support arises. During the first 5 years of coronary angioplasty, it was customary to insert a venous pacemaker into the right ventricle before starting the procedure. Often, this was combined with monitoring of the pulmonary artery pressures by using a Myler catheter. This endhole catheter was advanced into the pulmonary artery. The two electrodes located about 10 cm from the tip were usually leaning against the right ventricular outflow track, providing a fairly reliable opportunity for bipolar pacing. Later it was found that the need for pacing occurred quite rarely, particularly with the increasing use of nonionic contrast media. Moreover, the right ventricular pacemaker leads occasionally produced complications such as a right heart perforation with tamponade or arteriovenous fistulae at the puncture site in the groin. The technique of using the coronary guidewire (or any guidewire available) for emergency pacing in the coronary artery or the left ventricle was put forward as an option to forego completely venous puncture for people not quite ready to give up the safety feature of rapidly available cardiac pacing [1]. Although published in several journals and books and demonstrated at yearly live courses, the method was not adopted and fell to oblivion in most interventional centers. This was due to the lack of structured practical training in the technique and the rare need for pacing. In particular, it was completely ignored that it was not necessary to have a guidewire in good contact with the inside of a coronary artery to perform emergency pacing. In situations where no such wire is in place, any guidewire can be introduced into the left ventricle with the help of a diagnostic or a therapeutic catheter to be used for left ventricular pacing. The great majority of training centers for invasive and interventional cardiology still do not include these techniques among the options to treat sustained bradycardia in the catheterization laboratory. Hurried insertion of a transvenous pacemaking to the right ventricle is still considered the therapy of choice. The difference in speed between inserting a transvenous pacemaker and pacing over the coronary guidewire or a left ventricular wire may amount to only a couple of minutes. However, this may be essential in case of complete asystole. Coronary or left ventricular pacing can usually be installed within a minute, thereby obviating the need for cardiac massage. This is not true for transvenous pacing unless a venous introducer had been placed prophylactically. To do this, however, is not feasible for routine cardiac catheterization or percutaneous coronary interventions as the time and material invested and the risk of local complications such as bleeding or arteriovenous fistulae represent too high a price for what is at stake. As the method is not taught routinely, there is little experience with pacing over new generations of coronary guidewires. The new information provided is therefore useful. The key features for coronary pacing remain unchanged. The coronary guidewire needs insulation. Outside of the body, insulation is provided by the sterile drapes and the external portion of the catheter. Within the body, up to the coronary orifice, the catheter insulates the wire. Within the coronary artery, finally, there is no insulation unless a balloon catheter or something alike is advanced close to the tip of the guidewire. Most of the time the current is delivered to the tip of the wire just the same as blood is a poor conductor. The contact points of the wire in the coronary bends may account for loss of current without providing capture to the heart muscle. Therefore, to ensure capture, the wire tip has to lodge in a wedge position in a small coronary artery, preferably a intramuscular (e.g., septal) branch. The rest of the wire should be shielded as completely as possible by inserting whatever catheter is on the wire as distally as feasible. The negative pole of the temporary pacemaker should be connected to the wire. A noninsulated part of the outside end of the wire has to be used for connection to the pacemaker unit by an alligator clamp or simple squeeze between the gloved fingers. This is usually the very end of the wire. An alternative is to scratch off the insulation more closely to the entrance into the catheter as suggested by the authors. The positive electrode can be applied to any normal sticker used for ECG leads. Better contact can be achieved by a subcutaneous needle as suggested by the authors or, less painfully, by a large surface defibrillator patch applied to the chest or (more practically) to a thigh. To initiate pacing, the output of the temporary pacemaker should be put to maximum. Once pacing is established, the output can be turned down until capture ceases, then turned back up again just above the threshold level [2]. These things observed, basically any metallic wire can be used and exchange of the wire for pacing should rarely be necessary. A potentially lifesaving technique requiring nothing that is not already available during any diagnostic or therapeutic cardiac catheterization deserves being recalled to attention regularly. Fiddling around with a venous pacemaker to bail out of a temporarily slow heart rate problem or to convert sustained ventricular tachycardia [3] is not necessary while left heart catheterization material is already on the table [4].