The Smaller They Come

Percutaneous coronary angioplasty (currently summarized under the term PCI) started 25 years ago with roughly 10 French (Fr) guiding catheters that left no room for contrast medium injection. The actual angioplasty gear (ballon catheter with or without stent) has been miniaturized considerably more than the guiding catheters, which in many centers, still are 7 French. The gained space for contrast medium injection, in conjunction with the advent of digital angiography, has relegated difficult visualization to the non-issues. Do we take full advantage of this development in favor of the patient? The article by Schöbel et al. in this issue of the Journal points out that there is more to gain. The authors used 5 Fr guiding catheters in 1,200 consecutive patients with PCI through a femoral approach. In 5% of cases, they experienced the need for moving to a larger guiding catheter. See Schöbel et al. on pages 6–11 Opinions differ whether 5 French guiding catheters can be called “state-of-the-art”, or whether they are investigational and to be restricted to experienced operators and easy cases. The authors have dealt with all comers quite successfully. The results were standard. In the absence of a randomized trial, it can only be assumed that the small guiding catheter was no hindrance to the procedure. As they removed the introducers only hours after the intervention or sometimes even the next day, they may not have fully exploited the potential of small guiding catheters. The paucity of puncture site complications, with 2% hematoma and 1 false aneurysm in 1,200 patients in the absence of any blood transfusion or surgical intervention, is stupendous. Closure devices were not used. Manual compression was beyond doubt meticulous. Collection of data on local problems perhaps a bit less. It takes less than a prophet to predict that a smaller hole in an artery is a smaller problem than a larger hole. However, during the case, a 5 Fr catheter with a 5 Fr introducer (outer diameter of about 6.5 Fr) is approximately the minimum to comfortably work with in the face of a systolic blood pressure of about 140 mmHg and the typical elastic properties of an arterial wall. The next smaller dimension is the introducer for a 4 Fr catheter (5.5 Fr), which already shows a propensity for oozing. Oozing is the rule when using a 5 Fr catheter (1.7 mm), let alone a 4 Fr catheter (1.3 mm), without an introducer. The reason for more oozing during the procedure with small catheters than with large catheters is the fact that the arterial wall gets dilated more by a larger catheter. The elastic property of the vessel will crimp down on the catheter with sufficient force to withstand the systolic blood pressure only with a hole of a diameter above 1.5–2.0 mm. It has been possible to perform PCI through 4 French catheters since more than a decade.1 This has not been widely practiced, because it means technically pushing the envelope, and upgrading is necessary for stenting. Currently, virtually every PCI job can be accomplished with 5 French catheters, although some sophisticated equipment, such as directional atherectomy, brachytherapy, filter devices or kissing techniques are not an option. But who needs them anyhow? The beauty of PCI with a 5 French catheter has been illustrated by a case report where a single left Amplatz 5 French guiding catheter without an introducer was used to perform an emergency coronary angiogram including a left ventriculogram in a patient with acute myocardial infarction followed by PCI of several vessels.2 One is tempted to say that it will take about 2 years before 5 French PCIs will be the world standard, and that by that time, pioneers will be down to 3 French. This will not happen, as 5 French appears to be the technical limit of catheter fabrication to avoid kinking and also for the comfort for the operator. Who wants to struggle with an oozing groin throughout the procedure just to gain compression time and safety from a small hole once the catheter is out?

1. Moles VP, Meier B, Urban P, et al. Percutaneous transluminal coronary angioplasty through 4 French diagnostic catheters. Cathet Cardiovasc Diagn 1991;25:98–100. 2. Meier B. Frugal coronary angioplasty, a case for the simple approach. Cathet Cardiovasc Intervent (in press).