What is Right Ventricular Myocardial Infarction (Heart Attack)?
Damage to the right ventricle of the heart, which can sometimes include damage to the left ventricle, is becoming a more frequent diagnosis as medical technology and treatment options advance. This discussion will touch on important aspects related to the causes, diagnosis, and treatment of a condition called right ventricular myocardial infarction (RVMI).
RVMI was initially found in patients who had experienced heart damage in the lower wall of the heart. These patients had increased filling pressures in the right ventricle and signs of right ventricle failure, while the measures for the left ventricle remained normal. RVMI can happen regardless of whether the left ventricle is involved or not. When lower wall heart damage is coupled with RVMI, patients exhibit more slowing of the heart rate and a greater need for pacemaker, along with lower blood pressure and increased risk of death.
What Causes Right Ventricular Myocardial Infarction (Heart Attack)?
The right side of the heart is less likely to experience a heart attack than the left side. This is due to the right side’s thin walls, low need for oxygen, and lower pressures. However, disease caused by the build-up of fatty substances can often lead to a heart attack on the right side.
Risk Factors and Frequency for Right Ventricular Myocardial Infarction (Heart Attack)
Right ventricular myocardial infarction, a type of heart attack, along with inferior wall left ventricular dysfunction, a condition where the heart’s lower chamber doesn’t pump well, can occur together in 10 to 50% of cases. The wide range is largely due to the challenge of identifying these conditions in live patients. Autopsy results, however, show a higher rate. Isolated cases of right ventricular infarction or dysfunction, i.e. when it occurs on its own, are uncommon unless caused during heart procedures such as surgeries. Plus, it can get even more complicated because of a temporary condition called RV stunning, which could reduce the likelihood of detection.
Signs and Symptoms of Right Ventricular Myocardial Infarction (Heart Attack)
Right ventricular (RV) infarction refers to a specific type of heart attack that affects the right side of the heart. Like with traditional heart attacks on the left side, patients can experience discomfort in their chest that might radiate to other areas, shortness of breath, nausea, and feeling lightheaded. These patients might also have abnormal heart rhythms, leading to a slower-than-normal heartbeat or even complete heart block. An important symptom in these patients is low blood pressure.
In addition to these, there could be signs of right heart failure. This might manifest as sudden swelling of the legs, or distention (swelling) in the neck veins. The combination of neck vein swelling, clear lungs, and low blood pressure is typically seen in cases of right ventricular dysfunction. If there’s a leak in the tricuspid valve (the valve on the right side of the heart), a specific kind of murmur can be heard on examination, though this might not always be present. Sometimes, third or fourth heart sounds might be heard, and these intensify when the patient takes a deep breath in.
- Discomfort in the chest, sometimes radiating elsewhere
- Shortness of breath
- Nausea
- Dizziness
- Abnormal heart rhythms, slower-than-normal heartbeat or complete heart block
- Low blood pressure
- Sudden swelling of the legs
- Swelling in the neck veins
- Possible heart murmur
- Possible additional heart sounds that intensify on inhaling
About 30% of heart attack patients that affect the lower wall of the left heart also have involvement of the right heart, though significant heart functioning problems due to this right heart involvement is seen only in about 10% of such patients. If these patients are very sensitive to medications that lower the preloading (the extent to which the heart is filled with blood before it contracts to pump out the blood), like nitrates, morphine, or diuretics, it can suggest significant right heart dysfunction.
Testing for Right Ventricular Myocardial Infarction (Heart Attack)
An electrocardiogram (also known as an ECG) is usually the first test performed when a patient is experiencing chest pain. This test can provide evidence of issues with the left ventricle (a main pumping chamber of the heart) by showing abnormalities in certain heart monitors (leads II, III, and AVF). If there are concerns about the right ventricle of the heart, further examinations are needed, because a typical ECG doesn’t provide good clarity on this area of the heart. Distinct changes in how the heart’s electrical signals rise and fall can indicate trouble with the right ventricle and requires an ECG specifically focused on the right side. Certain changes in the heart’s rhythm, like right bundle branch block, slow heartbeat, or complete heart block can also appear on the ECG, but these can be quite vague signals.
Just like with issues related to the left ventricle, heart enzymes can increase with right ventricle heart attacks. But it can be tricky to differentiate between a serious lung-blood-clot scenario (pulmonary embolism) and right ventricle heart attack as some proteins, like troponin-I and CK-MB could be slightly raised in both cases.
Ultrasound scan of the heart (echocardiography) is quite effective for detecting issues with the right side of the heart. This test is becoming more easily accessible and thus is becoming the preferred choice for various settings like emergency departments and operating rooms. It has quite good sensitivity (82%) and specificity (93%) for detecting right ventricle heart attacks. Certain signs on this scan like abnormal wall motion of the right ventricle, abnormal movement of the wall between the two ventricles, leakage of the tricuspid valve or the pulmonary valve would suggest a right ventricle heart attack. Other measurements like the tricuspid annular plane excursion (TAPSI) are also being tested and may indicate a worsened prognosis.
Other tests like coronary angiography and ventricular scintigraphy are the “gold standards” in terms of definitive diagnosis but they have their drawbacks like being invasive and costly and are typically carried out during an intervention, so they aren’t used for initial evaluation. Regular chest X-rays can also provide clues about a potential right ventricle heart attack but have limited capabilities for diagnosis.
Likewise, monitoring of the blood pressures in various locations of the heart and lungs can provide important insights. An unusually high pressure in the right side of the heart and lungs compared to the left side, a distinct decline in the pressure in the big veins coming into the heart and an increase in pressure in the right atrium during breathing might all be clues towards a right ventricle heart attack.
Treatment Options for Right Ventricular Myocardial Infarction (Heart Attack)
If the right side of the heart isn’t working properly, it can cause issues with the left side of the heart, reducing the amount of blood being pumped out and potentially leading to low blood pressure. One way to manage this situation, if it’s suspected that the right ventricle of the heart is damaged (RVMI), is by giving the patient a “fluid challenge” of 500 milliliters of fluids. However, it’s crucial to observe the patient’s response since everyone’s fluid levels can vary. Using drugs called nitrates might actually make things worse as they can further lower blood flow.
If the fluids don’t work well enough, medication might be necessary. The most well-researched option here is a drug called dobutamine, which can help improve the heart’s ability to pump blood. Combining dobutamine with inhaled nitric oxide can also help lower resistance in the lungs’ blood vessels, which reduces the workload on the right side of the heart. Another drug, milrinone, can also help improve the right ventricle’s function by increasing its ability to contract and decreasing resistance in the lungs. However, milrinone isn’t specific to the lungs, and there are risks of worsening low blood pressure, so its use has to be carefully balanced.
For patients with issues on both sides of their heart, other measures might be needed, such as reducing the load on the heart with nitroprusside or a device called an intra-aortic balloon pump. Diuretics and vasodilators should be avoided if possible.
People with RVMI may also develop irregular heart rhythms because of the heart’s electrical system’s location. One particular issue is that their heart rate can directly affect how much blood is pumped out to the body. Specialized heart pacing can improve survival rates in these patients.
As with damage to the left ventricle of the heart, the earlier the treatment for RVMI, the better the chances of survival and recovery. Opening up the blocked vessel is the best treatment option, but dissolving the blood clot with medication can also be an option. Some patients may also benefit from devices that assist the heart in pumping blood, but further research is needed in this area.
Patients with RVMI typically have a worse short-term outlook than those with damage isolated to the left side of the heart, primarily due to the severe complications that can arise. However, the long-term prognosis for patients who receive proper treatment and recover from RVMI is similar to those with damage only to the left side of their heart.
What else can Right Ventricular Myocardial Infarction (Heart Attack) be?
When evaluating a patient, medical professionals might consider a wide variety of health conditions that might cause the symptoms. These could include:
- A sudden issue with the aorta, the main artery in your body (acute aortic dissection)
- Inflammation of your gallbladder often caused by gallstones (acute cholecystitis)
- Inflammation of your stomach lining, often caused by excessive alcohol use or prolonged use of nonsteroidal anti-inflammatory drugs (acute gastritis)
- A heart condition where a valve doesn’t close properly, which allows blood to backflow into the heart (acute mitral regurgitation)
- Inflammation of the thin sac-like membrane surrounding your heart (acute pericarditis)
- Mental health issues that are characterized by substantial worry, fear, and anxiety (anxiety disorders)
- A life-threatening condition involving a tear in the aorta (aortic dissection)
- A heart condition which narrows down the main exit of the heart (aortic stenosis)
- A common long-term condition in which a person’s airways become inflamed, causing coughing, wheezing and shortness of breath (asthma)
- Complications involving the gallbladder and bile ducts (biliary disease)
- A condition that causes a rapid loss of blood flow to your organs (cardiogenic shock)
Doctors take these possibilities into consideration and conduct necessary tests to arrive at the correct diagnosis.
What to expect with Right Ventricular Myocardial Infarction (Heart Attack)
The outlook for patients varies greatly and is influenced by a range of factors. Having a heart attack that affects the lower wall of the heart and also causes damage to the right ventricle (RVMI) tends to lead to worse outcomes than experiencing either of these conditions separately.
For patients that don’t have failure of the right ventricle, the in-hospital death rate within 30 days is 4.4% when treated with clot-dissolving therapy, and 3.2% when treated with a procedure to open blocked arteries (PCI). This number rises to 13% with clot-dissolving therapy and 8.3% with PCI among patients who do have right ventricle failure. In cases where patients have a type of severe heart attack that causes low blood pressure (cardiogenic shock), the death rate can rise to 100% with clot-dissolving therapy and 44% with PCI.
