arterial fibrillation Flashcards
(36 cards)
What is the definition of atrial fibrillation (A-fib)?
Answer: Atrial fibrillation is a supraventricular arrhythmia that originates above the ventricles and causes an irregularly irregular rhythm.
Name five mechanisms that can contribute to the development of atrial fibrillation.
Answer:
- Stretching of the myocardium
- Ischemia (decreased oxygen) to the myocardium of the atria
- Inflammation of the atria or nearby areas
- Increase in sympathetic nervous system (SNS) stimulation on the atria
- Electrolyte imbalance, particularly involving calcium (Ca2+) and potassium (K+)
What are the risk factors for atrial fibrillation?
Answer:
can be categorized as “cardiac causes” and “non-cardiac causes.”
The cardiac causes include congestive heart failure (CHF), dilated cardiomyopathy, valvular diseases (such as mitral stenosis and mitral regurgitation), coronary artery disease or myocardial infarction, rheumatic heart disease, and hypertension.
How does congestive heart failure (CHF) contribute to atrial fibrillation?
Answer:
- Congestive heart failure (CHF) causes increased stretching and distention of the myocardium of both the ventricles and the atria.
- This stretching leads to atrial dilation and hypertrophy, changing the morphology of the atria and increasing the risk of atrial fibrillation.
What is the mechanism behind atrial fibrillation in cases of valvular diseases?
Answer:
- Valvular diseases, such as mitral stenosis and mitral regurgitation, can contribute to atrial fibrillation through increased stretching of the atria.
- In mitral stenosis, the narrowed mitral valve allows less blood to flow from the atria into the ventricles, resulting in the retention of some volume in the atria and causing them to balloon up.
- Mitral regurgitation can have a similar effect, although it is less common.
How does ischemia contribute to the development of atrial fibrillation?
Answer:
- Ischemia, which refers to decreased oxygen supply, can trigger the development of atrial fibrillation.
- In severe coronary artery disease or myocardial infarction, if there is an ischemic or infarcted area, the tissue in the atria near that area must undergo remodeling.
- This remodeling can lead to abnormal electrical activities in the atria, resulting in atrial fibrillation.
What is the role of inflammation in atrial fibrillation caused by rheumatic heart disease?
Answer:
- In rheumatic heart disease, inflammation can affect the valves, atria, endocardium, or myocardium.
- The inflammation may be due to rheumatic fever.
- Rheumatic heart disease can lead to mitral stenosis, which ultimately increases the risk of atrial fibrillation.
- Additionally, the inflammation and atrial agitation caused by rheumatic heart disease can directly contribute to the development of atrial fibrillation.
What are the non-cardiac causes of atrial fibrillation?
Answer:
The non-cardiac causes of atrial fibrillation include lung pathologies, thyrotoxicosis or hyperthyroidism, holiday heart syndrome, pheochromocytoma, drugs (such as cocaine and methamphetamines), sepsis, surgical procedures, and electrolyte abnormalities.
How do lung pathologies contribute to atrial fibrillation?
Answer:
- Through ischemia caused by decreased oxygen supply (hypoxemia).
- Hypoxemia can trigger the atria to become irritable, leading to abnormal foci or reentry circuits and ischemia.
- Conditions such as chronic obstructive pulmonary disease (COPD), pneumonia, or acute onset pulmonary embolism can cause ventilation or perfusion problems, respectively, resulting in low oxygen levels.
What is the mechanism behind atrial fibrillation in cases of thyrotoxicosis or hyperthyroidism?
Answer:
- In cases of thyrotoxicosis or hyperthyroidism, there is increased sympathetic nervous system (SNS) activity.
- This leads to the release of excess thyroid hormones (FT3 and FT4), which increase β-adrenergic stimulation.
- The increased sensitivity of β1-adrenergic receptors to epinephrine and norepinephrine contributes to the development of atrial fibrillation.
What is holiday heart syndrome, and how does it lead to atrial fibrillation?
Answer:
- is a condition where excessive alcohol intake, such as acute alcohol binge-drinking, causes various effects on the body, including inflammation, electrolyte imbalance, and increased sympathetic nervous system (SNS) activity.
- Alcohol-induced cytotoxic effects lead to inflammation, while alterations in electrolyte levels, such as potassium (K+) and magnesium (Mg2+), can occur.
- These factors, combined with increased SNS effects on the heart, can result in atrial fibrillation.
What is pheochromocytoma, and how does it contribute to atrial fibrillation?
Answer:
- is a tumor located in the adrenal medulla that releases excessive amounts of catecholamines, including epinephrine and norepinephrine.
- These catecholamines bind to β1-adrenergic receptors, increasing calcium (Ca2+) influx and cation loading.
- This hyperactive sympathetic nervous system (SNS) activity leads to atrial agitation and can contribute to the development of atrial fibrillation.
Which drugs can increase the risk of atrial fibrillation?
Answer:
- Drugs such as cocaine and methamphetamines can increase the risk of atrial fibrillation.
- These drugs act as sympathomimetics, binding to the same receptors as epinephrine and norepinephrine, resulting in increased sympathetic nervous system (SNS) activity.
- This increased SNS activity leads to heightened cation loading and irritation of the atria, increasing the likelihood of atrial fibrillation.
How does sepsis contribute to the development of atrial fibrillation?
Answer:
- Sepsis is a condition characterized by a systemic inflammatory response to infection. During sepsis, the body experiences vasodilation, capillary permeability, and fever.
- In response to this stressful event, the sympathetic nervous system (SNS) becomes hyperactive as part of the “Fight or Flight” response.
- The increased SNS activity, intended to counteract the negative effects of sepsis, can lead to atrial fibrillation.
What is the relationship between surgical procedures and atrial fibrillation?
Answer:
- Invasive surgical procedures can cause significant post-operative stress on the body.
- This stress can trigger a catecholamine response, leading to hyperactive sympathetic nervous system (SNS) activity.
- The increased SNS activity, in turn, can contribute to the development of atrial fibrillation.
How do electrolyte abnormalities, specifically hypokalemia and hypomagnesemia, influence the occurrence of atrial fibrillation?
Answer:
- Electrolyte abnormalities, such as hypokalemia (decreased potassium levels) and hypomagnesemia (decreased magnesium levels), can alter the heart’s electrical activity and increase the risk of atrial fibrillation.
- Both potassium and magnesium are important cations involved in the electrical activities of the heart.
- Insufficient levels of these electrolytes can disrupt the normal electrical conduction system, leading to atrial fibrillation or supraventricular tachyarrhythmia.
How do the risk factors of increased stretch on the heart contribute to the pathophysiology of atrial fibrillation?
Answer:
- Increased stretch on the heart, as seen in conditions such as congestive heart failure (CHF), dilated cardiomyopathy, and mitral stenosis, can lead to remodeling of the myocardium.
- This remodeling can generate abnormal electrical activity in the atria, resulting in atrial fibrillation.
What is the role of inflammation of the myocardium in the development of atrial fibrillation?
Answer:
Inflammation of the myocardium, as observed in rheumatic heart disease, holiday heart syndrome, and increased reactive oxygen species (ROS) production, can agitate the atria and contribute to the occurrence of atrial fibrillation.
How does low oxygen delivery to the myocardium contribute to atrial fibrillation?
Answer:
Conditions such as coronary artery disease, myocardial infarction, chronic obstructive pulmonary disease (COPD), pneumonia, and acute pulmonary embolism can result in low oxygen delivery to the myocardium.
- This can trigger abnormal electrical activity in the atria, leading to atrial fibrillation.
What is the relationship between increased sympathetic activity and atrial fibrillation?
Answer:
Increased sympathetic activity, seen in conditions like thyrotoxicosis, pheochromocytoma, excessive alcohol intake, cocaine and methamphetamine consumption, septic reaction, and post-operative state,
can agitate the atria and contribute to the development of atrial fibrillation.
How does electrolyte imbalance, specifically hypokalemia and hypomagnesemia, contribute to atrial fibrillation?
Answer:
- particularly low levels of potassium (hypokalemia) and magnesium (hypomagnesemia), can alter the heart’s electrical activity.
- This disruption in electrical conduction can lead to atrial fibrillation or supraventricular tachyarrhythmia.
What are the two ways in which significant agitation to the myocardium can generate abnormal electrical activity?
Answer:
- Significant agitation to the myocardium, leading to remodeling, can result in the formation of ectopic foci in multiple areas in the myocardium of the atria.
- It can also lead to the development of re-entrant circuits, involving the alpha and beta pathways, which can generate abnormal electrical signals and contribute to atrial fibrillation.
What are common symptoms of atrial fibrillation?
Answer:
Common symptoms of atrial fibrillation include
- palpitations (abnormal awareness of heartbeat),
- shortness of breath, fatigue, and episodes of
- syncope (fainting).
How does atrial fibrillation contribute to cardiogenic shock?
Answer:
- In cases of tachycardia (heart rate»_space;> 150), there is not enough time for the ventricles to fill adequately.
- The reduced ventricular filling time leads to a decrease in end-diastolic volume, stroke volume, cardiac output, and mean arterial pressure.
- The decrease in cardiac output and hypotension can result in cardiogenic shock, which is characterized by inadequate blood flow to meet the body’s demands.
