Complications Related to Implantation of Coronary Stents

Until the advent of coronary stents, patients with cardiovascular blockages had little choice but to either keep a close eye on their disease (“watchful waiting” with or without accompanying pharmaceutical therapy) or undergo coronary artery bypass grafting (CABG). When angioplasty was developed by Andreas Gruentzig in 1977, patients were presented with the option to undergo angioplasty in an effort to open blocked coronary arteries. While short-term benefits were usually seen with balloon angioplasty, longer-term outcomes showed many arteries re-closing and requiring repeated intervention; up to 50% of angioplasty patients were found to require further angioplasty within six months. In an effort to reduce the frequency of patients requiring reintervention, scientists and clinicians developed stents that could be left behind to hold the artery open once the PTCA balloon was withdrawn.

Unfortunately, clinicians found that bare metal stents (BMS) could cause an immunological response that would try to “protect” the body from the foreign material (i.e., the stent). This, in turn, would lead to further narrowing near to or inside the stent, as seen in roughly 25% of patients receiving BMS devices. To combat this, drug-eluting stents (DES) were developed.

 

Potential Complications Associated with Coronary Stents

Complication
Description
Thrombosis

Local coagulation or clotting of the blood in the artery
Restenosis

The recurrence of abnormal narrowing of an artery or valve
Inflammation

Reddening, swelling, heating and pain caused by an immune response (exudation) to the implant
Hyperplasia

An abnormal increase in the number of cells in the surrounding tissue
Bleeding

Resulting from a biological reaction against the new stent implant, from perforation, or at the insertion site
Stent corrosion

Caused by stents that are not biocompatible. Can lead to restenosis, among other problems
Embolism

An obstruction in the artery due to a blood clot or air bubble, can lead to MI or stroke
Perforation, dissection

A puncture or tear in the arterial wall, made by the catheter
CABG or total occlusion of the artery

Bypass grafting may need to be performed in cases of acute complications
Stent failure

Can occur when the stent fails to expand properly or disengages prematurely from the balloon; can occur if the stent is improperly deployed; can result in emergency CABG or MI
Myocardial ischemia

Oxygen deprivation to the heart muscle accompanied by inadequate removal of metabolites because of reduced blood flow or perfusion
Stent migration

A dislodgement of the stent into the right cavities or pulmonary artery; can cause arrhythmia or MI
Death

The mortality rate associated with stenting can vary widely, depending on the stent used
Drug reaction, allergic reaction

A reaction to the drug on the stent or to the contrast medium used
Source: MedMarket Diligence, LLC
 
For the above reasons, combined with the highly attractive commercial market opporutnity for percutaneous treatment of coronary artery disease, manufacturers have continued to aggressively develop stent (and non-stent) technologies that improve upon (and gain share from) available stent technologies in clinical practice.
Drug-eluting stents were developed to release a drug (e.g., sirolimus or paclitaxel) intended to reduce the incidence of restenosis. From there, even more innovative products have been developed, such as bioactive stents or stents designed to attract a patient’s own endothelial cells to coat the stent.  Other device developers have sought to create stents that will fully degrade and disappear over a period of weeks or months— a score of companies in this area. Yet others seek to abandon the use of stents altogether, opting instead to pursue an angioplasty balloon that will leave the anti-inflammatory drugs behind without the accompanying stent.
 

Excerpted from "Worldwide Coronary Stents Market, 2008-2017", published May 2009, by MedMarket Diligence (see link for further details).

 

2 thoughts on “Complications Related to Implantation of Coronary Stents”

  1. While an elderly acquaintance was having a coronary stent implanted, she suffered a complication which left her two previously healthy kidneys essentially nonfunctional and required her to undergo dialysis.
    She described what doctors told her was an accident involving some sort of laser device used to attach the stent to the arterial walls. The surgeon missed the target with the laser and, instead, somehow hit both kidneys, damaging them supposedly permanently.
    My acquaintance underwent dialysis for three years, until blood work indicated that normal renal function had resumed.
    From what I know about anatomy and coronary stent implantation, her story has always been difficult to believe, but nonetheless, I would like to know if such a mishap is plausible. My father will soon be needing PCI.
    Thank you,
    Marie Barrett

  2. Marie:

    As a preface to my response to you, please note that I am not a medical doctor, and you should not make any medical decisions based on what I say here. My information should only be to augment your knowledge, which should also be combined with discussions with physicians involved procedures to be performed on you or anyone you know and care about. Having said this, I am very well-versed in the technologies used in the performance of percutaneous coronary interventions, and I should also note that I personally had a coronary stent implanted in 2003. Therefore, my knowledge is direct and personal as well.

    This case you describe is disconcerting, but I think that there are a couple of important unanswered questions. First, the use of lasers in the management of coronary artery disease is limited to creating an opening in the coronary artery’s lumen (i.e., the space inside the artery), especially in cases in which the artery blockage is so significant that a catheter cannot pass through that portion of the artery. Once the laser has created a sufficiently open lumen in the artery, the laser is retracted and may then be followed by insertion of a stent. The laser is not in fact used for attachment of the stent. (This is really a minor point of clarification and what you described since lasers can be used in the coronary artery, but not used directly for attachment of the stent to the artery wall.)

    Second, and probably more importantly, the use of a laser in a coronary intervention should not — in my opinion — produce any kind of discharge of the laser energy that could possibly injure the kidneys other than through gross negligence by the cardiologist, or interventional radiologist, performing the procedure. Certainly, the kidneys should never be injured when performing a coronary intervention and I would have to believe that the doctor or doctors, who treated your acquaintance had to have been held responsible for this injury. It should be noted that all surgical procedures, and that would include even percutaneous procedures, carry a certain amount of risk of collateral injury, or morbidity as it is medically described. Indeed, the performance of coronary interventions has a very specific risk of dislodging plaques from the arterial wall that can then circulate as embolisms that can cause serious injury and even death in patients. However, the injuries described to your acquaintance do not fall within the normal range of anticipated possible morbidity for coronary intervention.

    I wish I could be of more assistance, but without knowing what specifically were the circumstances of your acquaintence’s procedure, and how the injuries actually occurred, my perspective on it has to be limited to what I have described here.

    I hope this is helpful.

    Patrick Driscoll

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