Term
| Bundle Branch Block is caused by a block in conduction of the __ or __ bundle branch. The BBB delays depolarization to the __ that it __. |
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Definition
- Right or Left
- ventricle that it supplies |
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Term
| Normally both ventricles depolarize together, but with a bundle branch block, one ventricle depolarizes slightly after the other. This causes __ __ __ to appear on the EKG. We name the peaks __ and __, __ representing the delayed depolarization of the blocked ventricle. |
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Definition
- two joined QRSs (since there is 2 it is a wider QRS complex greater than 3 sqaures or 0.12seconds)
- R and R'
- R' |
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Term
| The diagnosis of Bundle Branch Block is mainly based on the widened __, being __ or more in duration. |
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Definition
- widened QRS
- being 0.12 seconds (three small squares) or more |
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Term
| __ and __ are RIGHT CHEST LEADS. This is where you would look for the RR' for RBBB. |
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Definition
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Term
| __ and __ are LEFT chest leads. This is where you would look for the RR' for LBBB. |
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Definition
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Term
| RBBB produces an __ in the right chest leads __ and __. |
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Definition
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Term
| With a __ __ resulting in dx of BBB, then look at right and left leads to determine which side block is on. |
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Definition
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Term
| The left bundle branch has two subdivisions or ___. Blocks of these fascicles are called __. |
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Definition
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Term
| Hemiblocks are blockages of either the __ or ___ divisions of the ___ bundle branch. |
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Definition
- anterior or posterior
- left |
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Term
| Common causes of bundle branch blocks: |
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Definition
- Idiopathic
- Hypertension
- Congenital Heart Disease
- Ischemic Heart Disease
- MI
- Valvular Heart Disease
- Infections of the myocardium
- COPD
- Trauma |
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Term
| RIGHT BUNDLE BRANCH BLOCK EKG findings: |
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Definition
- widened QRS (3 small squares or more)
- R,R' in V1, V2
- downsloping ST segment/ T wave changes in septal leads V1 and V2
- slurred S wave in lateral leads V5 and V6 |
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Term
| An incomplete RBB will still have ____ changes in V1 and V2 but not a widened QRS. |
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Definition
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Term
| With left bundle branch block, you CANNOT make a diagnosis relevant to ___. With RBBB you can. This is an important distinction. |
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Definition
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Term
| RBBB is not always deadly. But LBBB is ALWAYS sign of __ ___ __. |
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Definition
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Term
| Blockage of conduction in the left bundle branch prior to its bifurcation results primarily in delayed depolarization of the left ventricle |
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Definition
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Term
| Bifascicular block can be blockages of any 2 of the following: __ __ __, __ __ __, __ __ __. |
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Definition
- Right bundle branch
- Left anterior bundle branch
- Left posterior bundle branch |
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Term
| A Trifascicular Block is blockage of all three fascicles below the __ __, so the __ __ __, __ __ __, and __ __ __ are all blocked with this condition. These patients usually also have ___. |
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Definition
- AV node
- Right Bundle Branch
- Left Anterior Fascicle
- Left Posterior Fasicle
- bradycardia |
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Term
| Hemiblocks aka fascicular blocks main effect on the EKG is to change the __ __ without changing the __ or __ of the __ _ _form. Hemiblocks are commonly associated with _ __ __. |
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Definition
- change the QRS axis
- without changing shape or duration of QRS wave form
- coronary artery disease |
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Term
| Hemiblocks are usually associated with __ __ __. |
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Definition
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Term
| If you have a left or right axis deviation look for a __/__ block. |
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Definition
| hemiblock/fascicular block |
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Term
| Left posterior hemiblock will have __ __ __, the QRS will NOT be widened. |
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Definition
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Term
| Trifascicular block refers to a block of all three fascicles (but with intact AV conduction). |
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Definition
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Term
| Barron said won't have to do Hemiblock EKGs on test. Might need to check this. |
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Definition
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Term
| Prolongation of the QT interval increases the risk for __ __ __ a potentially fatal ___ ___ ___. When the QT interval is prolonged, it is __ that is really prolonged meaning the heart is more likely to be stimulated during this vulnerable state. |
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Definition
- Torsades de pointes
- polymorphic ventricular tachycardia
- repolarization |
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Term
| Torsades/Long QT syndrome epidemiology: |
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Definition
About 3000-4000 deaths in the United States each year
The cumulative mortality rate reaches approximately 6% by the age of 40 years
Race: No clear evidence suggests race-related differences in the occurrence of LQTS |
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Term
| Long QT Syndrome is a disorder characterized by a prolongation of the __ __ on the EKG and a propensity to __ __. Usual presentations include __, __ __, or __ __. |
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Definition
- QT interval
- ventricular tachyarrhythmias
- syncope
- cardiac arrest
- sudden death |
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Term
| The QT inteval is measured from the beginning of the __ wave to the end of the __ wave, representing the time required for __ and __ of the __. |
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Definition
- Q wave
- T wave
- depolarization and repolarization of the ventricles |
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Term
| Long QT syndrome can be __ due to __ __ __, or ___ and__ __. |
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Definition
- congenital due to ion channel abnormalities
- acquired and drug induced |
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Term
| Prolonged QT interval pronlongs the recovery from electrical excitation and __ the refractory period. |
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Definition
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Term
| The QT interval varies __ with heart rate, and correction of heart rate or the __ __ must be made. |
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Definition
- inversely
- R-R interval
(QT intervals may vary a lot b/w leads)
fast the heart rate the shorter the QT interval |
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Term
| The Bazett Equation helps you calculate the QT interval corrected for heart rate: |
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Definition
QTc= QT/sqaure root of R to R interval
QTc= QT interval corrected for heart rate
this equation has many limitations. One being the heart rate at which Qt was measured. B/c perfectly normal person will have longer QT intevals with a slower heart rate |
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Term
| General population average QTc: |
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Definition
| 0.38-0.40 seconds (or 380-400 msec) |
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Term
The duration of the QT interval is affected by a number of physiologic and pathologic factors, including - importantly - by the heart rate at which the QT is measured. As you can see in the six seconds of ECG displayed in each of these two sample tracings, the presence of more complexes per unit time will simply have the effect of shortening the intervals between each complex. In addition however, the QT intervals within each complex are shortened as well. So, a perfectly normal heart has a longer QT interval at a lower heart rate than at a higher heart rate. One option for expression of QT might be to include the heart rate at which the QT was measured, e.g. QT 420 at 66 bpm. However, by convention, the QT interval is instead “corrected for heart rate” by application of a mathematical correction formula. The formula incorporates terms for heart rate and QT, producing a QTc. The correction formula first proposed by Bazett in 1920 became the standard used in the literature, and remains the most commonly employed. However there are others, and I will later review the effect of correction formula upon the findings of our comparative QTc trial.
While it is true that an average QTc in an average population is a difficult number to pin down, 400 msec is a reasonable estimate, consistent with much of the epidemiological literature. |
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Definition
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Term
| Drugs that prolonge the QT interval: |
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Definition
- Macrolides (erythromycin, clarithromycin)
- Ketoconazole
- Amiodarone
- Fluoxetine (Prozac) antidepressant
- Beta agonists like Salmuterol
So if someone already has a prolonged QT interval, do NOT give them one of the above drugs. Could lead to Torsades. |
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Term
| Torsades multiple hit hypothesis suggests that __ __ like IKr blockers plus a second risk factor is what leads someone into Torsades. What are these other risk factors? |
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Definition
- drug exposure
- Risk factors:
- Bradycardia
- Hypokalemia
- Female gender
- Metabolic inhibitor
- other QT prolonging drugs
- underlying heart disease (CHF, LVH, AF)
- Genetic polymorphism (IKr or IKs) |
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