Sinus Rhythm Flashcards
What is sinus bradycardia?
dysrhythmia originating in the SA node with a ventricular response of less than 60bpm
What is sinus tachycardia?
A dysrhythmia originating in the SA node with a ventricular response between 101-180 bpm
What are the characteristics of a rhythm that begins in the SA node?
A positive P wave before each QRS ( in lead 2)
P waves that look alike
A constant PR interval
A regular atrial and ventricular rhythm (usually)
What can affect an electrical impluse that begins in the SA node?
Medications
Diseases or conditions that cause the HR to slow down or speed up
Diseases or conditions that delay or block the impulse from leaving the SA node
Diseases or conditions that prevent an impulse from being generated in the SA node
What is the rate of a NSR (normal sinus rhythm)?
60-100bpm
What does a wide QRS in a NSR signify?
A delay in the bundle branch conduction
What is severe sinus bradycardia?
Sinus rhythm with a ventricular response of less than 40bpm
What are causes of sinus bradycardia?
disease of SA node Hyperkalemia Hypokalemia Hypothermia Hypoxia Hypothyroidism Increased ICP Inferior MI Calcium channel blockers Digitalis Beta-blockers Amiodarone Posterior MI Vagal stimulation
What are the signs and symptoms of haemodynamic compromise?
Acute changes in mental status Chest pain or discomfort Cold, clammy skin Fall in urine output Heart failure Low bp Pulmonary congestion Shock SOB
What is the management of someone who has symptomatic bradycardia?
Include assessment of sats, and whether or not there is evidence of increased work of breathing. Give supplemental oxygen if sats are inadequate. Assist breathing if ventilation is inadequate. Establish IV access and obtain a 12-Lead. Atropine is administered.
What is atropine?
Blocks Ach receptors at the neuromsusclar ends of the vagus nerve. This allows for more sympathetic activity
What is atropine most effective for?
Narrow QRS complex bradycardias
What is sinus arrhythmia?
Dysrhythmia arising in the SA node that occurs when the SA node discharges irregularly, sinua arrhythmia is a normal phenomenon associated with the phases of breathing and changes in intrathoracic pressure
What are the characteristics of sinus tachycardia?
P waves is positive in lead 2 and morphologically regular.
101-180bpm
R-R and P-P intervals are regular
At very fast rates it may be difficult to tell between a p wave and a t wave
What can cause sinus tachycardia?
Some people complain of palpitations or a pounding in their chest.
Sinus tachycardia is seen in some patients with acute MI, especially in those with an anterior infarction.
Why do we need to consider sinus tachycardia in patients with coronary heart disease?
Sinus tachycardia increases cardiac workload and decreases filling time. Leading to both decreased oxygen output and increased ischaemia.
Sinus tachycardia in a patient who is having an acute MI may be an early warning sign for heart failure, cardiogenic shock and more serious dysrhythmias
What are the causes of sinus tachycardia?
acute MI Caffeine dehydration/hypovolemia Drugs such as cocaine, amphetamines, ecstacy, cannabis Fever HEart failure Hyperthyroidism Hypoxia INfection Pulmonary embolism Shock Sympathetic stimulation
What is sinus arrhythmia?
When the SA node fires irregularly.
What rate does sinus- arrhythmia occur at?
usually 60-100. Any thing slower in sinus brad-arrhythmia or faster is sinus tachy-arrhythmia
What is a sinoatrial block?
aka the sinua exit block
The pacemaker cells in the SA node initiate an impulse but it is blocked as it exits the SA node. this results in periodically absent PQRST complexes.
Why is SA block thought ot occur?
Because of failure of the transitional cells around the SA node to conduct the impulse to the surrounding atrial myocardium.
How do we identify a sinoatrial block?
There is a single missed beat in a sinus rhythm that is exactly the length of one normal beat.
What is sinus arrest?
aka sinus pause or sinoatrial arrest.
The pacemaker cells of the SA node fail to initiate an electrical impulse for one or more betas resulting in absent PQRST cmplexes on the ECG
What symptoms may be associated with sinus arrest?
Haemodynamic compromise Light headedness Weakness Dizziness Syncope
How do we manage sinus arrest.
Remove any tight clothing that may be stimulating the vagal nerve.
What does lead 2 view/
The inferior surface of the left ventricle
