What is Coronary Sinus Thrombosis?
The system of veins in the heart, known as the coronary venous system, is often not widely discussed in medical literature. Despite the fact that the coronary sinus – a large vein on the heart – is an important access point for many heart-related procedures, diseases involving this system are not usually encountered by medical professionals. However, there are exceptions in specific cases such as birth defects.
A rare and serious condition associated with this system is the formation of a blood clot in the coronary sinus, known as coronary sinus thrombosis. This condition often occurs as a complication after performing procedures on the right side of the heart. Occasionally, it can also occur without any apparent reason.
What Causes Coronary Sinus Thrombosis?
Just like blood clots anywhere in the body, a clot in the coronary sinus (a vein that collects blood from the heart muscle) can occur due to slow blood flow, changes in blood clotting, or damage to the inner lining of the blood vessels.
Several medical procedures involving the right side of the heart have been linked to these clots. These include the placement of a central venous catheter (a tube placed into a large vein), the insertion of an electrode into the coronary sinus for heart synchronization, and the temporary use of a catheter in the coronary sinus during heart surgery.
Other procedures, like implanting a defibrillator in people with severe heart disease, inserting a shunt to alleviate brain fluid build-up (hydrocephalus), or performing procedures to fix heart rhythm problems, may also result in damage to the vessel lining, leading to clots.
In some cases, these coronary sinus clots occur without any obvious injury to the vessel’s interior lining. These are referred to as spontaneous clots and are often linked to pre-existing conditions. These might include heart rhythm problems (atrial fibrillation), right heart failure, problems with the heart’s tricuspid valve, chronic obstructive pulmonary disease (a type of lung disease), lung-related heart disease caused by lung scarring, Kawasaki disease (an inflammatory disease in children), or acute lymphoblastic leukemia (a type of cancer that affects white blood cells).
Apart from this, heart infection, especially fungal infections, can also cause these spontaneous clots. Additionally, widespread infection (sepsis) and altered blood clotting can play a role in triggering clots in the coronary sinus. These spontaneous clots may also occur as a result of complications from abdominal infections or Crohn’s disease (a chronic inflammatory bowel disease). There have also been instances where a big clot from the heart chambers extends into the coronary sinus, leading to a clot in this vein.
Risk Factors and Frequency for Coronary Sinus Thrombosis
Coronary sinus thrombosis, a serious heart condition, is rarely reported or happens rarely. Interestingly, most of the documented instances are acute or sudden-onset rather than chronic or long-term, making up more than 80% of the cases. This is surprising given the large number of patients who have ventricular pacemakers inserted via the coronary sinus, which could potentially increase the risk of this condition.
These pacemakers are typically installed in seriously ill individuals suffering from severe cardiomyopathy, a disease of the heart muscle. If these patients suddenly pass away, it’s not often investigated further with a postmortem exam. Because of this, it remains unknown whether coronary sinus thrombosis contributes to some of these deaths.
There is no noticeable gender difference in the occurrence of this condition. It’s likely that coronary sinus thrombosis is often missed by medical professionals because of patients’ rapid health decline and the limited familiarity of cardiologists with the condition. Due to the typically severe nature of acute cases, many end fatally, often identified only during an autopsy. This likely contributes to under-reporting of how often the condition actually occurs.
Signs and Symptoms of Coronary Sinus Thrombosis
Coronary sinus thrombosis is a serious condition that’s hard to diagnose due to its non-specific symptoms and rarity. The condition can lead to severe symptoms and even sudden death, given its rapid progression and high mortality rate. Early studies have shown that blockage in the flow of blood through the coronary sinus can lead to symptoms like:
- Chest pain
- Shortness of breath
- Low blood pressure
- Changes in the electrocardiogram such as ST-segment elevations
- Accumulation of fluid in the sac surrounding the heart (pericardial effusion)
- Cardiogenic shock (a condition where the heart can’t pump enough blood around the body)
- Sudden cardiac death
Sometimes, only a partial blockage of the coronary sinus occurs, which doesn’t cause immediate death due to alternative blood flow paths. However, this partial blockage can remain unnoticed until further complications, such as complete occlusion, occur. This can result in potentially life-threatening situations like pulmonary embolism (blockage in one of the lung’s arteries due to a blood clot) or myocardial dysfunction or infarction (heart muscle damage or heart attack).
Testing for Coronary Sinus Thrombosis
If the coronary sinus, a blood vessel in your heart, is expanded, it can be viewed via a heart ultrasound (transthoracic echocardiography). The ultrasound shows the heart from two different angles: the parasternal long-axis view and the apical 4-chamber view. However, the coronary sinus is seen even more clearly with a different type of ultrasound called a transesophageal echocardiography. This creates other views: a modified mid-esophageal 4-chamber and bi-canal views.
On the flip side, some patients have a condition called chronic coronary sinus thrombosis, which doesn’t show any symptoms and can only be spotted during unrelated heart examinations like CT scan angiography or routine echocardiography. In severe cases, this condition can lead to sudden cardiac death. Unfortunately, it’s often not identified until an autopsy is performed soon after death, as there are often no clinical signs that lead to diagnosis. Most deaths caused by acute coronary sinus thrombosis are unnoticed until autopsy results reveal clotted blood (thrombosed) in the coronary sinus.
Treatment Options for Coronary Sinus Thrombosis
There currently isn’t a clear consensus on the best way to treat coronary sinus thrombosis, a blood clot in the heart’s coronary sinus. The effect of aspirin, a blood thinner, is uncertain. There are a few different treatment options often used, though neither has been definitively proven the best.
In emergency situations, surgeons may remove the blood clot from the coronary sinus, a procedure known as thrombectomy. After the surgical removal of the clot, physicians generally administer an anti-clotting medication called heparin, followed by another medication called warfarin. This combination is typically used in both stable and unstable patients.
For patients in stable condition, an alternative approach uses a lower-dose version of heparin, bridging into either warfarin or a new type of oral anticoagulant medicine. This method also seems to be effective.
While these treatments appear beneficial, it’s important to note that there’s not enough data to confirm whether they indeed improve survival rates or reduce health complications. We need more concise guidelines and further research to understand the long-term management of this condition, especially regarding the use of new oral anticoagulants.
What else can Coronary Sinus Thrombosis be?
Coronary sinus thrombosis (a blood clot in your coronary sinus) can be tricky to pinpoint because its signs can resemble other health problems. In fact, doctors don’t usually consider it as one of the initial potential diagnoses, probably due to its subtle symptoms and the lack of wide experience dealing with it. So, when you have symptoms like chest pain, breathlessness, low blood pressure, increased heart rate, higher levels of a heart damage indicator called troponins, and signs of insufficient blood supply to the heart on an ECG, they are more likely to suspect you might have a heart attack. To distinguish between a heart attack caused by coronary sinus thrombosis and one caused by coronary artery disease, your doctor might use a coronary angiogram, a special X-ray test that uses a dye and camera to take pictures of the blood flow in the coronary arteries. This test is important since the treatments for both types of heart attacks are different.
If you have a fluid build-up around your heart (pericardial effusion), your doctors will want to identify whether it’s due to coronary sinus thrombosis or other conditions like cancer, infection or autoimmune disorders. This is crucial because treatments vary greatly depending on the cause.
If you are critically ill with coronary sinus thrombosis, you might experience a type of shock called cardiogenic shock. Here, your doctors should do more tests to differentiate it from septic shock, a severe infection that triggers body-wide inflammation.
If your coronary sinus appears enlarged due to thrombosis, the doctors should consider other causes of an enlarged coronary sinus. This might be due to birth defects that result in an unusually high amount of blood returning to the coronary sinus. Such conditions might include a persistently open vein (patent left SVC), abnormal return of blood from the liver and lungs, or an abnormal connection between a coronary artery and a vein (a coronary arteriovenous fistula). An enlarged coronary sinus could also be a sign of heart failure on the right side of the heart or high blood pressure in the arteries that supply the lungs (pulmonary hypertension).
What to expect with Coronary Sinus Thrombosis
The outlook for acute cases is generally unfavorable, with over 80% of patients experiencing severe complications leading to heart failure. However, individuals who have been incidentally diagnosed with a chronic form of coronary sinus thrombosis and show no symptoms are less common, and their outlook tends to be more positive with aggressive treatments. These treatments may include effective anticoagulant medicines to prevent blood clots and potentially also a procedure to remove the thrombus, known as a thrombectomy.
Possible Complications When Diagnosed with Coronary Sinus Thrombosis
As previously noted, the clotting of the coronary sinus, a blood vessel that carries deoxygenated blood from the heart muscle, can lead to severe and life-threatening complications if not diagnosed and treated early. These complications can include:
- Acute myocardial ischemia: a sudden decrease in blood flow to the heart
- Myocardial infarction: commonly known as a heart attack
- Pulmonary embolism: a blood clot in the lungs
- Pericardial effusion: buildup of excess fluid around the heart
- Cardiac tamponade: pressure on the heart due to fluid accumulation
- Cardiogenic shock: the heart’s inability to pump enough blood to meet the body’s needs
- Sudden cardiac death: an unexpected death caused by loss of heart function
