CMC Review Questions Flashcards
What is radiofrequency ablation? What can it treat?
-electrical energy that creates heat and causes thermal injury and local tissue destruction
Treats: AV nodal Reentry Tachycardia (AVNRT) WPW AFib (AV node ablation)- insert perm pacemaker too Atrial tachycardia (SVT) AFlutter AFib- pulmonary vein ablation, MAZE Monomorphic VT (pt has to be able to tolerate the VT for the procedure)
How is hypokalemia identified on ECG?
-ST segment depression, flattened T waves, enlarged U waves, prolonged QT interval
- sometimes the U wave merges with the T wave to create a “camel hump” appearance
- increased risk of Tdp
Defibrillation vs Cardioversion
Defib:
- unsynchronized, delivered any point in cardiac cycle
- used for VF and [pulseless] VT
- pads anterolateral (right chest, left lateral)
- Biphasic: 120-200 joules
Cardioversion:
- SYNCHRONIZED on QRS (avoid hitting T wave)
- used for VT with pulse, unstable Afib/Aflutter/SVT
- pads anterior-posterior (goes thru short axis) [same for pacing]
- 50-200 joules
What are the pacemaker codes?
- Chamber paced (A, V, Dual)
- Chamber sensed (none, A, V, Dual)
- Response to sensing (none, trigger, inhibit, Dual)
Triggered means- when it senses chamber, triggers output (uncommon)
Inhibited- when it senses chamber, inhibits output (meaning the pt’s own intrinsic beat is seen w/o pacing spike)
Pacemaker capture vs sensing?
CAPTURE- ability of the pacing stimulus to depolarize the chamber being paced
following the pacing spike would be a p wave or QRS complex If these do no correlate with the pacing spike, then loss of capture is present (emergency in pacemaker dependent pt)
SENSING- ability of the pacemaker to recognize and respond to intrinsic depolarizations
***if there is no intrinsic activity to sense, this can’t be evaluated (meaning every beat has pacing spike)
**so essential, capturing is present if spike followed by expected cardiac cycle; sensing present if intrinsic beat recognized.
What is done to correct complete loss of capture?
Increase the mA (output) and reposition the patient, the wire is no longer in contact with the myocardium
What is done to correct loss of sensing?
Increase the sensitivity (turn dial to smaller number)
-if there is an intrinsic beat and a pacing spike followed with paced beat, then it was not sensed
**the danger with loss of sensing is the potential for pacemaker spikes landing too close to the T wave and initiating VT or VF
What happens if pacemaker oversenses?
Oversensing occurs when a pacer incorrectly senses noncardiac electrical activity and is inhibited from pacing. This may result in a heart rate lower than the preset rate.
[magnet turns off sensing]
What are the 4 states of pacing with DDD pacing?
- AV sequential pacing (paces pike, pwave, pace spike QRS complex)
- Atrial pace, ventricular sense (creates atrial impulse that then conducts in the ventricle)
- Atrial sense, ventricular pace (Senses atrial impulse, creates QRS complex)
- all inhibited, no pacing
In DDD mode, there is no such thing as straight ventricular pacing, there is either always an atrial sensed beat or an atrial paced beat before the ventricular paced beat unless it has mode switched
-with dual pacing, the maget will turn off the atrial sensing to disrupt pacemaker mediated tachycardia
External defibrillation for pt with ICD pad caution? What does the magnet do?
- Do not place over generator, Pads should be 4-6inches away from ICD
- It may take 2min or more to deliver all programmed therapies, so don’t wait and externally defib
- The magnet deactivates arrhythmia detection and treatment functions, but does not turn off the pacemaker function [removal returns the ICD to previous programmed parameters]
What is brugada syndrome?
Individuals with Brugada syndrome may experience irregular heartbeats (ventricular arrhythmias) or may have no apparent symptoms (asymptomatic).
-Inherited channelopathy gene mutations that affect regulation of cardiac sodium channels
Irregular heartbeats may cause difficulty breathing, loss of consciousness or fainting (syncope), seizures, and SUDDEN CARDIAC DEATH (usually 1st symptom)
ECG: STE >2mm w/ inverted Twave
What does a LHC evaluate? What are the access points?
- coronary arteries
- LV function
- measure LV & aortic pressures
- mitral & aortic vavles
- done for PCI procedures and catheter based valve procedures
~ARTERIES: femoral, radial, brachial
What does a RHC evaluate? What are the access points?
- Right heart function
- measure PA pressures and CO
- detect left-to-right shunt
- pulmonic & tricuspid valves
- perform EPS
~VENOUS: femoral, internal jugular, subclavian
Signs of cardiac perforation or tamponade?
Beck’s Triad: hypotension, JVD, muffled heart sounds
- tachycardia
- pulsus paradoxus (a fall of SBP of >10 mmHg during the inspiratory phase.)
- dyspnea
- chest pain
Signs of pneumothorax?
dyspnea
unequal breath sounds
chest discomfort
How can a hematoma and pseudoaneurysm be differentiated?
A pseudoaneurysm will have a pulsatile mass (thrill) with a systolic bruit over the insertion site. The blood flows in/out of hematoma cavity. So auscultate!
What is the treatment for symptomatic SVT?
-Valslva maneuver, if that doesn’t work then urgent cardioversion.
[if pt not symptomatic with hypotension, chest pressure, nausea and dizziness, then give ADENOSINE to convert the pt]
What are pts at risk for with posterior wall MI?
Papillary Muscle rupture (most common with inferior posterior STEMI)
- may hear new holosystolic murmur
- results in severe mitral valve regurgitation and subsequent acute life-threatening cardiogenic shock and pulmonary edema (crackles, new holosystolic murmur, sudden onset of SOB, narrow pulse pressure, hypotensive)
- requires IABP to reduce LV afterload until surgical intervention (meds for arterial vasodilation can’t be tolerated d/t already being hypotensive)
How do you determine if there is right or left axis deviation or normal?
LEFT: This is reflected by a QRS complex positive in lead I and negative in leads aVF and II.
RIGHT: This is reflected by a QRS complex negative in lead I and positive in leads aVF and II.
What is early sign that CO is decreasing?
- narrowing of pulse pressure d/t rise in DBP
* as CO ↓the SNS compensates by ↑HR and causing peripheral vasoconstriction. The vasoconstriction causes DBP to rise.
What are late signs that CO is decreasing?
-drop in SBP, decreased UOP, and hypotension
Which lead is best to monitor a patient following coronary artery intervention?
Lead III
-It will show STE if there is RCA reocclusion and it will usually show ST depression if there is LAD or circumflex artery reocclusion
What are EKG changes with Hyperkalemia?
Mild 5.5-6.5
-peaked T waves, narrow at base
Moderate 6.5-8
- PR interval prolonged
- P wave flattens or disappears
- STE
- QRS begins to widen
Severe >8
- further widening of QRS
- VF
What are the 6 Ps of acute arterial occlusion?
Pallor- pale, delayed cap refill Polar - cold to touch Pain - distal in extremity Pulseless- compare both sides Paresthesa- numbness, tingling d/t ischemic nerve dysfxn Paralysis- ischemia nerve dysfunction
What is Virchow’s Triad?
the theory that venous thrombobembolism occurs as a result of:
- alterations in blood flow (statsis from bedrest)
- vascular endothelial injury
- alterations in the constituents of the blood (inherited or acquired hypercoagulable state)
What are systolic murmurs?
Heard when the ventricles are squeezing:
- Aortic stenosis (valve open but narrow)
- Pulmonic stenosis (valve open but narrow)
- Mitral regurg (closed but backflow occurs)
- Tricuspid regurg (closed but backflow occurs)
- Mitral valve prolapse
- ASD
- VSD
- hypertrophic cardiomyopathy
What are diastolic murmurs?
Heard when ventricles are filling:
- Aortic regurg (closed but backflow occurs)
- Pulmonic regurg (closed but backflow occurs)
- Mitral stenosis (open but narrowed)
- Tricuspid stenosis (open but narrowed)
How does CPAP help?
maintains positive airway pressure at the end of expiration, rather than letting it return to zero. It’s basically PEEP.
[no machine breaths delivered, pt controls rate and TV]
When is BiPAP used?
for pts w/ evidence of inadequate ventilation like increased work of breathing or elevated PaCO2 on ABG.
It’s biphasic positive airway pressure: pressure support during inspiration combined with CPAP (pressure at end of expiration)
What presents as widespread ST elevation?
Pericarditis
[note: the pain is often relieved by sitting up and leaning forward]
