What is Paradoxical Embolism?
A paradoxical embolism is a rare cause of a sudden blockage in an artery. It happens when a clot or a similar substance travels through a flaw in the heart and enters the body’s circulatory system. Depending on where the clot ends up, patients may experience different symptoms.
The clot can travel to various places including the brain, heart, digestive system, or limbs. This can cause symptoms like strokes, chest pain, migraines, cold limbs, or digestive issues due to reduced blood flow. The blockage is usually a blood clot, but it can also be a fat particle, air, amniotic fluid, or a tumor.
The treatment approach for a paradoxical embolism can vary. Treatment may include medication and/or surgery, depending on where the clot is located. Often, doctors will treat their patients before they can completely confirm a diagnosis of a paradoxical embolism, due to the difficulties in making a definitive diagnosis.
What Causes Paradoxical Embolism?
A patent foramen ovale (PFO) is a hole between the two upper chambers of your heart that stayed open after birth. This opening can sometimes allow blood to go from the left side to the right side of your heart. The amount of blood that goes from right to left might increase your chances of having a stroke with no known cause.
Certain actions like coughing, squatting, or using the bathroom can cause your right heart chamber’s pressure to go up. This can briefly reverse the blood flow and potentially send blood clots into your body’s circulation.
Atrial septal defects (ASDs) are birth defects that might make a hole in the heart in different sizes and locations. They might cause quick or irregular heartbeats or take your breath away. ASDs also usually lead to a blood flow from left to right in the heart. However, this can sometimes be reversed. Up to 14% of people with an ASD might also have a blood clot that appears in a location where they usually don’t.
Ventricular septal defects are often responsible for a blood flow from left to right. However, certain conditions that increase the right heart’s pressure, like Eisenmenger syndrome, can reverse the flow. This could also result in a blood clot in an unexpected place.
Pulmonary arteriovenous malformations are usually inherited and are an abnormal connection between pulmonary arteries and veins returning to the left heart chamber. This leads to a permanent blood flow going right to left. People with hereditary hemorrhagic telangiectasia, a genetic disorder, have a higher risk for these malformations and subsequent unexpected blood clots.
Risk Factors and Frequency for Paradoxical Embolism
Cerebrovascular accidents, or strokes, are the second leading cause of death globally, often related to an unusual condition called a paradoxical embolism. Up to 45% of strokes due to blockage in the blood supply (ischemic strokes) don’t have clear causes, like irregular heartbeat, and these are known as cryptogenic strokes. The frequency of paradoxical embolism is hard to calculate because diagnosing it is tricky.
- A hole in the heart (PFO) might be found in 30% of the population.
- Research indicates that the yearly risk of cryptogenic and recurring strokes in people with a PFO is 0.1% and 1% respectively.
- ASDs, or holes in the section of the heart that divides the two upper chambers, are 2 to 3 times more common in females.
- ASDs account for over 30% of heart defects present from birth in adults.
- In cases of ischemic stroke without a clear cause, a paradoxical embolism should be considered.
Signs and Symptoms of Paradoxical Embolism
Paradoxical Embolism can be hard to identify and may develop subtly, often in patients suffering from an embolic event with no identifiable source like atrial fibrillation. This is particularly true when the patient has a suspected or known intracardiac shunt or pulmonary arteriovenous malformation (PAVM). To properly diagnose the condition, a detailed patient history and physical evaluation is absolutely crucial. Depending on the specific organ affected by the embolism, the symptoms can vary.
The following are some vital questions that doctors might ask:
- Identifying factors that may have caused the episode, such as coughing or straining
- Screening for conditions like high blood pressure, deep vein thrombosis, cardiovascular disease, diabetes, high cholesterol, atrial fibrillation, stroke, and fainting spells.
- Checking if the patient has a history of migraines (as migraines are common in up to 50% of patients with an intracardiac shunt)
- Investigating a history of congenital heart disease, structural heart disease, or a patent foramen ovale
- Discussing family history
- Asking about lifestyle choices, such as tobacco use
In the physical examination, medical professionals need to check for:
- Signs of congenital heart defects which may include right ventricular hypertrophy, abnormal growth of fingers and toes, or a constant splitting of the second heart sound
- Conducting a complete neurological evaluation, looking for symptoms like speech or visual abnormalities, weakness on one side of the body, seizures, and difficulties with swallowing
- Assessing peripheral pulse and checking for signs of limb ischemia, where the affected limb may suddenly become cold, pulseless, and painful
Testing for Paradoxical Embolism
When trying to diagnose paradoxical embolism – a medical condition where a blood clot travels from the veins to the arteries – doctors first rule out other potential reasons that could be causing the patient’s symptoms.
As part of the evaluation, doctors typically conduct numerous tests:
* An EKG (a test that checks the heart’s electrical activity) to look for irregular heart rhythms.
* A transthoracic echocardiogram (TTE, an ultrasound of the heart) with color-flow Doppler. This test helps the doctor see if there are any abnormal blood pathways in the heart, tumors, or clots. They might also use a technique involving a liquid called saline or contrast, which when injected helps them visualize any unusual pathways better. In order to spot a specific type of hole in the heart (a PFO), the saline or contrast needs to be injected when the patient is performing a certain manoeuvre. TTE can also help detect plaque in the ascending aorta (the portion of the largest artery in the body that emerges from the heart).
* Transcranial Doppler sonography (TCD), a non-invasive procedure that can be done at the patient’s bedside. It involves injecting a contrast agent into a peripheral line (a tube placed into a vein) and looking for tiny clots in the middle cerebral artery (a major artery that supplies blood to the brain).
* Ear oximetry, a simple screening tool for detecting abnormal pathways in the heart. It works by detecting a decrease in the amount of oxygen in the blood when the patient performs a certain manoeuvre.
* Coagulation studies, are tests to measure how long it takes your blood to clot. Including tests for protein C and S antigen levels, proteins in our blood that help prevent blood clotting.
* D-Dimer test, if a lung clot (pulmonary embolism) is suspected.
* Arterial blood gas test, which measures the oxygen level in the blood.
* Ultrasound to check for a deep vein thrombosis (DVT), a blood clot that forms in a deep vein.
* CT angiography scan of the chest to check for a lung clot.
* Noncontrast CT scan of the brain to look for bleeding in the brain.
* CT angiogram or MRI to look for acute (sudden) blood clot in the extremity, kidneys, or bowel.
* Additional blood tests and urinalysis as required, to check for other potential causes.
Treatment Options for Paradoxical Embolism
Treatment of paradoxical embolism, an unusual type of blood clot that travels from your veins to your arteries, usually involves a mix of medical treatment and surgery. There are three main ways to treat this condition:
1. Close the route that allowed the clot to move from the vein to the artery. This can be done using surgery or a percutaneous approach, which is a procedure done through the skin.
2. Medicine can be used to prevent more blood clots from forming in your veins.
3. A mix of both surgery and medication can be used.
The best treatment approach for each person is based on several factors, including the risk of having another stroke, the long-term benefits and risks between clot-preventing therapy and surgery, and the cost of each treatment. Surgical options may include closing holes within the heart and treating Pulmonary Arteriovenous Malformations (PAVMs), which are abnormal connections between arteries and veins in the lung. Medical treatment consists of blood-thinning (antithrombotic) therapy with medicines such as aspirin, clopidogrel, or warfarin. These medicines can help prevent blood clots from forming.
Initially, anticoagulation, a type of medication that prevents blood clots, is always used for treatment. If the patient has a hole within the heart, it can be closed by either a minimally invasive procedure or open-heart surgery. Today, there are many devices that help close these holes with a lower risk of complications.
In an emergency situation where the patient’s vital signs are unstable, thrombolysis, a treatment to dissolve dangerous clots in blood vessels, is often used. Both Deep Vein Thrombosis (DVT), a blood clot in a deep vein, and pulmonary embolus, a blockage in one of the pulmonary arteries in the lungs, need long-term treatment with blood-thinning medications. Some patients may need to take blood-thinning medications for life.
What else can Paradoxical Embolism be?
These are some conditions related to vein and heart issues:
- Deep vein thrombosis (a blood clot in a deeper vein)
- Septic phlebitis (vein inflammation due to an infection)
- Varicose veins (enlarged, swollen, and twisting veins)
- Endocarditis (inflammation of the inner lining of the heart)
What to expect with Paradoxical Embolism
The outcome after a paradoxical embolism, which is an unexpected blockage in blood flow, can vary widely. This depends on which organ is affected and how much damage has been done. If the brain (collectively referred to as CNS or Central Nervous System) is involved, patients usually face the most challenging outcomes.
However, there is hope for those who experience a lack of blood flow to the mesenteric region (the part of the body that includes the intestine) or those who suffer from a ‘cold leg’, a term for lack of blood supply to the leg. Both of these conditions can often be treated successfully with surgery. Unfortunately, kidney damage (known as renal infarction) due to a paradoxical embolism tends not to recover.
Possible Complications When Diagnosed with Paradoxical Embolism
Possible challenges that can arise include:
- Paralysis of one side of the body (Hemiplegia)
- Unexpected, uncontrollable muscle movements (Seizures)
- Difficulty with expressing or understanding language (Aphasia)
- Lack of strength (Weakness)
- Problems with speaking (Speech deficits)
- Heart attack (Acute myocardial infarction)
- Irregular heartbeat (Arrhythmias)
- Failure of the kidneys (Kidney failure)
- Loss of use of a limb due to its removal (Amputation)
- Potential death
Recovery from Paradoxical Embolism
Patients with a paradoxical embolus, which is a type of blood clot that’s moved from one part of the body to another through an abnormal connection in the heart, often need to stay in the hospital for a longer time. Some might even need to be in the Intensive Care Unit (ICU) for more detailed observation. If the occurrence of a Deep Vein Thrombosis (DVT) or a Pulmonary Embolism (PE), which are types of blood clots in the veins or the lungs respectively, are confirmed, usually anti-clotting drug treatments are necessary for around six months. It’s crucial to closely keep track of the International Normalized Ratio (INR) in patients. INR is a test to measure how long it takes for your blood to clot and helps avoid the risk of another similar issue cropping up.
