Book stuff Flashcards
Supraventricular tachycardias
Rapid rhythm disturbances origin in from the atria or the AV node
- often are considered paroxysmal SVTs (since they come and go in episodes)
Can occur in 3 mechanisms
- reentry (most common)
- enhanced automaticity
- triggered activity
Reentry arrthmias require what?
An area of slow conduction must be found somewhere (ischemia/blockage)
Each limb must have a different refractory period
What do automaticity Arrhythmias require?
Either a single or multiple foci firing independently from the SA node
- enhanced = foci fires spontaneously either within the sinus node or not. Does not have a disease associated with it
- abnormal = same as enhanced except a diseases process does exist
Atrial flutter is defined as
Heart rate usually 150-300
P wave rates hover around 250-340
- shows in a “sawtooth” pattern
- usually 2-4:1 ratio of f waves: QRS complexes
R-P relation is undefined since the P waves are actually f waves and moving too fast
can also show neck venous pulsation of about 300/min
What can be done to the patient who is suspected of atrial flutter to confirm it?
Give adenosine
Use vagal maneuvers
Diffference between isthmus-dependent clockwise atrial flutter and isthmus-dependent counterclockwise
Clockwise:
- Positive f waves in leads 2,3, and aVF
- negative f waves in lead V1
Counter wise:
- positive f waves in lead V1
- negative f waves in leads 2,3 and aVF
WPW diagnosis
Genetic issues where bypass tracts are present, but may or may not mean tachyarrhythmia
- show a short PR interval
- Wide QRS complex
- secondary repolarization abnormalities
- presence of delta waves
Tx:
- vagal maneuvers
- adenosine
- BBs or CBBs
When you replace potassium, what electrolyte must be replaced first?
Magnesium
How to treat hyperkalemia?
Give calcium (stabilize the myocardium)
Give glucose/insulin (to uptake the excess potassium)
- NEVER give calcium to a patient with hyperkalemia due to digoxin-induced, will kill*
When is surgery indicative for aortic stenosis?
1) symptomatic patients w/ severe obstruction marked by any of the following
- valve area <1cm
- LV systolic dysfunction (<50% EF)
- aneurysmal aortic root/ascending aorta
2) asymptomatic patients with aortic stenosis who are also required to get CABG (coronary artery bypass grafts)
Normal through severe classifications of mitral valve stenosis
Normal: No treatment
- 0 mmHg pressure gradient
- > 4.0 cm valve area
Mild: no treatment
- 1-5 mmHg pressure gradient
- 2.5-4.0 cm valve area
Moderate: no treatment except *
- 6-10 mmHg pressure gradient
- 1.0-2.5 cm valve area
- *pulmonary capillary pressure >25mmHg w/ exercise (requires percutaneous mitral balloon valvotomy(PMBC/V)
Severe: requires surgery unless no atrial fibrilation is present
- > 10 mmHg
- <1.0 mitral valve area
- usually presents w/ atrial fib
- can be asymptomatic or symptomatic
- surgery includes PMBV unless patient is not a high surgical risk, then Mitral valve replacement
AHA definition of CHF and cardinal signs
Complex clinical syndrome that results from structural or functional impairment of ventricular filling and/or ejection of blood.
- cardinal signs include
1) dyspnea
2) fatigue/syncope
3) systemic edema
4) rales in lungs “crackling sounds in lungs”
Difference between diastolic and systolic heart failures based on AHA guidelines
Systolic = Heart failure w/ a reduced ejection fraction
Diastolic = Heart failure w/out a reduced ejection fraction
the cut off is <40% ejection fraction
Possible etiologies of heart failure
1) any conditions that alter left ventricular structure and function
- HCM
- DCM
- MI
- patient ductus arteriosis
- endocarditis
- mitral/aortic stenosis or regurgitation
- CAD most common cause 75%
- HTN induced LVH second most common cause 70%
- diabetes
- duchennes, Becker’s and limb girdle dystrophies (causes DCM)
- rheumatic heart disease (causes valvular defects and LVH)
Pathogenesis of Heart failure
Progressive disorder that is almost always initiated after an “index event”
- index event is one of 2 things:
1) damage to myocytes w/ loss-of-function
2) disruptions in the ability for the heart to generate force (RCM, valvular diseases, ETC)
Compensatory mechanisms for LV dysfunction that prevent acute Heart failure
1) activation of RAAS system
2) activation of nervous system
3) increases in myocontractility (concentric hypertrophy in LVH)
4) increases in natriuretic peptides
5) increases a in bradykinin, prostaglandins and nitric oxide production (natural vasodilation to decrease SVR)
* all of these cause many patients with LV dysfunction to remain asymptomatic until clinical heart failure is present*
Left ventricular remodeling biological steps
The official title for the process in which asymptomatic HF becomes symptomatic HF
1) individual myocyte hypertrophy
2) alterations in contractile properties of myocytes
3) progressive less of total myocytes
4) B-adrenergic desensitization
5) abnormal myocardial metabolism (increases in oxygen demand)
6) changes in ECM that do not provide strucutre support for myocytes (unorganized new collagen)
Potential Biological stimuli for the progressive of LV remodeling
1) increased mechanical stress of myocytes
2) neurohormones (angiotensin and NE)
3) inflammatory cytokines
4) endothelin
5) ROS