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multifocal atrial tachycardia otherwise known as an 84 short answer type of super reticular tachycardia its classically associated with elderly people with chronic lung disease specifically COPD and in conjunction with old parts that are predisposed to conduction abnormalities or talk about what causes damage he lets take a look at the heart so here looking at the cross section of the heart of actually hurt me so i sat down the middle get the inside of the heart over here we have the right atria and then we have the left atrium because we're looking at the patient's heart the right side is over here on the left side is over here we're looking at the patient the heartbreaking contains the hearts dominant pacemaker the S a node near the Sno in the atria live multiple automatically 40 side which serve as backup Pacers in the event that the dominant SA node fail in a normal heart heart be originated from the SA node in 15 travels to the structure here call the AV node and a single carries down through the ventricles the figure causes the ventricles to contract that's when you feel your heartbeat however in MHT pacemaker actually no longer originate from the SA node but rather from multiple automaticity fossa each other to city focus paces at its own rate so as a result multiple piecing centers are false ID fire at the same time but no organized fashion so they're also any signals of the ventricles contract for the ventricles are getting signals from multiple patients enters this is going to cause a tachycardia or heart rate is greater than a hundred feet per minute on EKG MIT can be identified diagnosed based on three main criteria one is at the heart rate is greater than a hundred because I'm et tachycardia you'll also see greater than or equal to three different P wave morphologies which is a fancy word for shapes and you have variation in the PR intervals meaning that they'll be different late let's look at an EKG with 180 you'll notice that this person is a tachycardia weak at heart rate by looking at the boxes so we start at a bar in her role may go one box that stands for 300 boxes 850 beats per minute and Xbox is a hundred beats per minute so a person would have a heart rate of $150 are in her role was somewhere over here you'll notice that the RRR interval is always less than three boxes this person is definitely natak kar diya just like classic M et there are at least three different shapes of P wave so notice how each P wave look slightly different and there is variation in the PR interval this period rules about four boxes and this one's about 5 also every he has an irregular rhythm and we'd like to look for this is by drawing and dot above the bar interval and you can notice after you got all of these that there isn't even spacing between each dot so this represents an irregular rhythm finally a.m. et has narrow QRS complexes that means that the QRS complex is less than or equal to zero point 12 seconds or three small boxes near curious complexes signify that the abnormality is coming from the atria now I have a meaty commonly seen in people with heart and lung disease well it's thought that what makes people particularly vulnerable to MHT is atrial distortion where the atria because pathologically enlarged drawing large atria and this can be due to years of COPD coronary artery disease and heart failure if they can leave at the central distension as a possible underlying mechanism of MHT however can't be the only mechanism because we definitely see a medium people without pathologically a large atria also know that you can see pathological enlargement and the left or the right atria or even both within and a large atrium make someone more vulnerable to the risk factors of a meaty so what are the risk factors well anything that increases intracellular calcium in the cardiac myocyte this increase in intracellular calcium needs to spontaneous calcium relief during a window time when calcium typically it's a relief and this causes untimely depolarization mean that I'll say faulty polarize during a time when it shouldn't such as a refractory period several things cause increases intracellular calcium such as hypokalemia which is a low-level potassium similarly hypomagnesemia can also cause an increase in the shower calcium hypomagnesemia can actually promote hypokalemia through potassium wasting in the kidney hypoxia is another common risk factor that we see in AM ET and again this is seen a lot of our patients have COPD and other risk factor acidemia which is a pathologically low pH again we see this in patients with COPD who have chronic hypoxia as well as people who just suffered a heart attack or myocardial infarction otherwise he was never my heart's compromise I can circulate blood to the tissue and so people become a sardonic finally people with severe infections leading to sepsis can also have acidemia