A heart stent is a small mesh tube that is used to treat narrowed or blocked coronary arteries. Stents are inserted into the artery during an angioplasty procedure to keep the artery open and restore blood flow to the heart muscle. Over time, stents can become clogged or blocked again in a process called in-stent restenosis. If this happens, another procedure may be required to unblock the stent and reopen the artery.
What is a heart stent and how does it work?
A stent is a tiny, expandable metal mesh tube that is inserted into a narrowed coronary artery during an angioplasty procedure. Angioplasty is a minimally invasive procedure where a balloon-tipped catheter is used to open a blocked or narrowed artery. During an angioplasty, the surgeon will first insert a guidewire through the artery to the site of the blockage. Next, a balloon-tipped catheter is passed over the guidewire to the blockage. The balloon is then inflated which pushes the plaque outwards against the artery wall, flattening it and widening the artery.
Once the artery is opened, the stent is positioned over the inflated balloon and expanded. As the stent expands, it presses against the inner wall of the artery, acting as scaffolding to keep the artery open. The balloon is then deflated and removed, but the stent remains in place permanently, propping open the artery and improving blood flow to the heart.
Stents are usually made of metal alloys and come in a few different shapes. The most common are bare metal stents and drug-eluting stents. Bare metal stents are made of stainless steel or cobalt chromium. Drug-eluting stents are coated with medications that help prevent the regrowth of scar tissue and reduce the chances of restenosis. Over 3 million stents are implanted in patients worldwide each year.
What causes a heart stent to become blocked?
A major complication that can occur after stent placement is called in-stent restenosis. This is when scar tissue and plaque start to re-narrow the stented artery, eventually leading to blockage. There are a few reasons why in-stent restenosis happens:
– Neointimal hyperplasia – This is an overgrowth of vascular smooth muscle cells and scar tissue inside the stent. The artery may become blocked again over time as this tissue proliferates.
– Plaque progression – Even with the artery propped open, fatty deposits called plaque can continue building up inside the stent.
– Blood clots – A blood clot may form inside the stent, blocking blood flow. This is more common with bare metal stents.
– Mechanical problems – On rare occasions, the stent may shift out of place or structural problems with the stent could obstruct blood flow.
– Incomplete stent expansion – If the stent does not fully expand against the arterial wall during placement, sections could remain narrowed.
Restenosis can occur slowly over months or years after stent implantation. Various factors can increase the risk of restenosis, including multiple stents, long stented segments, small diameter arteries, and medical conditions like diabetes.
What are the symptoms of a blocked heart stent?
A blocked heart stent may cause symptoms similar to those of the original artery narrowing and angina:
– Chest pain or tightness, especially during activity
– Shortness of breath
– Fatigue, dizziness or lightheadedness
– Heart palpitations
If a stent becomes completely obstructed, it can also lead to a heart attack. Seek emergency medical care immediately if you develop any of these symptoms:
– Prolonged or intense chest pain
– Nausea, sweating, dizziness associated with chest discomfort
– Pain spreading to shoulders, arms, neck or jaw
– Difficulty breathing or shortness of breath
Routine follow-up and cardiac testing can often detect a blocked stent before major symptoms develop. Contact your cardiologist right away if you have new or worsening heart-related symptoms after receiving a stent.
How is an obstructed heart stent diagnosed?
If symptoms indicate a possible blocked stent, your cardiologist will perform one or more of the following diagnostic tests:
Angiogram – This is the gold standard test to visualize the coronary arteries. A catheter is inserted into an artery and threaded up to the heart. Contrast dye is injected while x-ray images are taken. Blockages and narrowing are clearly seen, along with stents and their patency.
Echocardiogram – Uses ultrasound waves to create images of the heart’s structure and movement. Can show areas of heart muscle that are damaged or not contracting normally due to poor blood flow.
Nuclear stress test – Involves injecting a small amount of radioactive material into the blood. Then a scanner tracks this material as the heart works under exertion on a treadmill or medicine-induced stress. Blockages and poor blood flow are detected based on imaging results.
CT coronary angiography – A CT scanner takes detailed images of the coronary arteries after contrast dye injection. Provides 3D views of blockages.
Cardiac MRI – Uses a powerful magnetic field and radio waves to image the structure and function of the heart. Can assess areas being deprived of oxygen due to a blocked stent.
If one of these tests confirms a significant blockage within a stent, your cardiologist will discuss the various options available for reopening it.
How is a blocked heart stent reopened?
If a major blockage is present within the stent, another procedure will be required to restore blood flow. There are several methods that can be used:
Angioplasty and stent placement – Just like the original procedure, balloon angioplasty can be performed to open the obstructed stent. Often, an additional new stent is implanted inside the old one to prop it open.
Atherectomy – Using a tiny rotating blade on the end of a catheter, atherectomy devices are designed to remove plaque build-up inside the stent. The blade shaves the clogging material away to clear a path for blood to flow through.
Laser angioplasty – A catheter with a laser tip is threaded to the site of the blockage. The laser is activated to vaporize the plaque inside the stent.
Orbital atherectomy – This system uses a diamond-coated orb that rotates at very high speed to sand away plaque obstruction within the stent. As plaque is ablated away, blood flow is restored.
Cutting balloon angioplasty – A special balloon catheter covered with tiny blades is inserted into the blocked stent. As the balloon inflates, the blades cut through the scar tissue and openings are created to reopen the artery.
The specific technique used will depend on the individual patient situation and blockage characteristics. In some cases, just balloon angioplasty alone may be sufficient to reopen a blocked stent. Adding stents and using atherectomy devices have proven effective for stubborn obstructions.
Are there medications available to help prevent stent blockages?
Yes, certain medications can help reduce the risk of developing in-stent restenosis that leads to stent blockages:
Anti-platelet drugs – Medications like aspirin and clopidogrel (Plavix) help prevent blood clots by inhibiting platelet aggregation. These are routinely prescribed after stent placement.
Statins – Used to lower LDL cholesterol, statins like atorvastatin (Lipitor) and rosuvastatin (Crestor) can stabilize existing plaque and slow the growth of scar tissue.
ACE inhibitors – This class of blood pressure medications may prevent restenosis through effects on the renin-angiotensin system and vascular remodeling.
Drug-eluting stents – These stents have specialized coatings that slowly release medications to inhibit cell proliferation and regrowth of plaque. Common drugs used include sirolimus and everolimus.
Following medication instructions carefully after stent implantation is key. Make sure to take all prescribed drugs as directed to get the maximum benefit for preventing restenosis and stent blockages.
What is the outlook for patients with a blocked stent?
The prognosis after a stent becomes obstructed depends on several factors:
– How soon the blockage is detected and treated
– If heart damage has occurred from loss of blood flow
– Overall heart health and other medical conditions
– Effectiveness of the procedure to reopen the artery
– If symptoms can be controlled with medications and lifestyle changes
In many cases, a blocked stent can be successfully cleared with repeat angioplasty or atherectomy procedures to fully restore blood flow. However, there is an increased risk of the artery becoming narrowed again. Medications and lifestyle modifications are still important after reopening a blocked stent.
With prompt treatment, patients who develop in-stent restenosis often continue to do well and maintain an active lifestyle. Close monitoring and follow-up testing are recommended to check for recurrent blockages. Avoiding known heart disease risk factors like smoking, obesity, and inactivity is also advised.
Overall, a blocked stent is a serious complication but does not mean a poor long-term outcome, especially with comprehensive heart care. Work closely with your cardiologist for optimal management if stent obstruction occurs.
Lifestyle changes to prevent stent blockages
While stents help keep arteries open, certain lifestyle measures can also help prevent stent blockages from developing:
– Quit smoking – Smoking is a major risk factor for coronary artery disease and in-stent restenosis. Quitting is critical.
– Follow a heart healthy diet – Eat plenty of fruits, vegetables, whole grains and lean protein. Avoid saturated fats, excess salt and added sugars.
– Exercise regularly – Get at least 30 minutes of moderate activity most days of the week. Brisk walking, cycling and swimming are great options.
– Lose weight if overweight – Reaching and maintaining a healthy body weight reduces strain on the heart and arteries.
– Limit alcohol – Drinking too much alcohol can raise blood pressure and cholesterol levels, increasing restenosis risk.
– Manage stress – Finding healthy ways to cope with stress promotes heart health. Try meditation, yoga, or deep breathing exercises.
– Monitor blood pressure – Keeping blood pressure optimized helps prevent damage to artery walls.
– Take medications as prescribed – Properly adhering to all medications after stent placement is vital.
Combining heart-healthy lifestyle choices with medical management provides the best protection against developing recurrent blockages after stent implantation.
When to seek emergency care for a blocked stent
In most cases, the development of a blocked stent is not a medical emergency. Symptoms often come on slowly, prompting a visit with your cardiologist to diagnose and treat the obstruction. However, in certain situations, a blocked stent requires emergency medical care:
– Severe chest pain, especially if pain lasts more than 15 minutes
– Pain or discomfort accompanied by shortness of breath, sweating, nausea
– Sudden onset of lightheadedness, confusion, loss of consciousness
– Signs of shock such as low blood pressure, rapid heart rate, clammy skin
– Recent history of stent placement (within the past 6 months)
– Known high-grade blockage or prior stent obstruction
– Presence of other high-risk factors like diabetes, smoking, or heart failure
If a blocked stent leads to a heart attack, immediate treatment is vital to save heart muscle and prevent life-threatening complications. Call 911 or have someone drive you to the emergency room right away if you experience any critical symptoms. Rapid evaluation and management in an emergency setting are crucial when heart damage or heart attack are suspected.
Frequently Asked Questions
How long do heart stents last?
Most stents will continue to function for many years after implantation. Clinical studies have shown the vast majority of stents remain open for at least 10 years. However, a small percentage of patients will develop in-stent restenosis within the first year. Routine follow-up is important to monitor for blockages.
What are the risks of a blocked stent?
A blocked stent can reduce blood flow to the heart muscle, leading to angina and heart attack risk. Sudden stent closure is rare but can result in ventricular fibrillation, heart failure, or cardiac arrest. Seek care immediately if you have symptoms of a blocked stent.
How often does stent restenosis occur?
With today’s modern drug-eluting stents, the rate of restenosis is relatively low, around 3-10%. Older bare metal stents had restenosis rates up to 20-30%. High-risk patients like diabetics have higher rates of developing stent blockages.
Can you feel a stent in your heart?
No, stents are very small and made of flexible, thin mesh that conforms to the inner artery wall. Patients usually cannot feel the stent or notice its presence once it is implanted in the artery.
What happens if you don’t treat a blocked stent?
An untreated fully blocked stent can lead to a heart attack, heart failure, arrhythmias, cardiac arrest and death. Even a partially blocked stent can cause stable angina. Prompt evaluation and treatment are essential if stent obstruction is suspected.
Conclusion
Heart stents provide important scaffolding to keep arteries open after angioplasty. However, over time, stents may become clogged again due to restenosis. A blocked stent can reduce blood supply to the heart. Symptoms like chest pain and shortness of breath often prompt diagnosis. Tests like an angiogram can confirm obstruction within the stent. Reopening the blockage is achieved by repeat angioplasty, stenting, atherectomy or other catheter-based techniques. Medications and lifestyle changes are also key to prevent recurrent stent blockages. With prompt treatment, the prognosis after fixing a blocked stent is generally very good. Close follow-up care with a cardiologist is recommended. While stent restenosis is not uncommon, advanced therapies allow most patients to successfully regain patency and proper heart artery function.
