Optical Coherence Tomography (OCT) Complications
Optical coherence tomography (OCT), a high-resolution intravascular imaging technology, is useful for distinguishing the etiology of occlusive disease (for example, plaque vs intramural hematoma vs thrombus) in addition to evaluating lesion severity, stent expansion, stent-wall apposition, and complications associated with stent placement. Unlike intravascular ultrasound (IVUS), visualization by OCT requires injection of viscous material, typically contrast, to “clear” blood from the field. Complications due to OCT are infrequent, but include:
1. Embolization of lesion material due to forceful contrast injection required for performance of OCT;
2. Hydraulic extension of vessel dissection due to forceful contrast injection.
Complications With Guide Extension Catheters
Guide extension catheters are a relatively recent and now invaluable addition to the interventional armamentarium (Supplemental Figure 1A-C). Uptake of these devices for use in complex PCI continues to increase (Supplemental Figure 2). Their principal role is to assist stent or balloon delivery when there is insufficient support from the guide catheter alone. The extension is delivered deeper into the coronary artery (“mother-child” technique), providing improved support and reducing friction with the proximal vessel wall.1 The most commonly used extensions are the GuideLiner (Vascular Solutions) and Guidezilla (Boston Scientific). Each is available in 6, 7, and 8 Fr calibers for use in corresponding guides (Supplemental Figure 1A-C). Complications — and strategies to prevent them — will be discussed and illustrated through representative cases.
Complications From Guide Extensions
1. Traumatic dissection.
Traumatic dissection is caused by the razor-edge of the extension tip traumatizing the arterial lining upon advancement (Supplemental Figure 1A-C). This is the most common and serious complication encountered with these devices. Strategies to minimize guide-extension related dissections are detailed in the following cases.
2. Hydraulic dissection.
Hydraulic dissection occurs when contrast is inadvertently injected, despite pressure damping being seen on the monitor. In these cases, the operator fails to recognize that the guide extension is tightly fit within the guide, such that there is no “blow-off” capability at the guide tip with contrast injection (example follows).
3. Arrhythmias and ischemia. Arrhythmias and ischemia can be due to occlusion from the guide extension catheter, particularly with smaller caliber coronary arteries.
4. Stripping of stents at the proximal aspect of the guide extension shaft.
5. Longitudinal stent distortion and/or stent collapse. Longitudinal stent distortion and/or stent collapse can occur if a guide extension is used to force a non-compliant balloon into a stent for post-dilatation or advancing a second stent more distally.
The problem of a step transition between pushing rod and extension tube (where the stent edge could catch) has existed with the newer generations of guide extension catheters.