Types of Heart Blocks
First Degree
Second Degree (Type 1 Mobitz)
Second Degree (Type 2)
Third Degree
First Degree Heart Block
- all atrial impulses are conducted through AV node into the ventricles but at a rate slower than normal.
- Rate of P waves to QRS is 1:1
- PR intervals are extended longer than 0.20 seconds
- Atrial and ventricular rate/rhythm depend on underlying rhythm
- P wave and QRS should be normal
Second Degree, Type 1 (Mobitz) Heart Block
- When all but one of the atrial impulses are conducted through the AV node into ventricles.
- Each atrial impulse takes longer (extended PR interval) to be conducted than the previous one until one impulse is fully blocked.
- Ratio of P waves to QRS is > than 1:1
- QRS shape and duration is usually normal
Second Degree, Type 2 Heart Block
- When only some of the atrial impulses are conducted through the AV node into ventricles.
- PR interval is consistent when they are followed by QRS complexes, normal length
- QRS shape and duration is usually abnormal
- Usually atrial rhythm is regular but RR may be irregular
- Ratio of P waves to QRS is > than 1:1
Third Degree
- No atrial impulse is conducted through the AV node into ventricles.
- Two impulses stimulate the heart. One stimulates the ventricles (junctional or ventricular escape rhythm), represented by QRS complex. Another stimulates the atria (sinus rhythm or atrial fibrillation), represented by P wave.
- P waves can be seen but electrical activity is not conducted down into the ventricles to cause QRS complex, called AV dissociation.
- PP and RR intervals are regular but not related to each other.
- QRS shape and duration depend on whether a junctional or ventricular escape rhythm is present
- PR interval is irregular
- Ratio of P waves to QRS complexes is > than 1:1
Treatment of Heart Block
- Based on cause of block and patient stability
- Goal: increase heart rate to maintain normal cardiac output
- Symptomatic if patient has: SOB, chest pain, dizziness, or low BP
- IV bolus of atropine is initial treatment
- If patient does not respond to atropine or has an acute MI TCP should be started
- Permanent pacemaker may be necessary for a chronic block
Normal ECG waveform
P wave
PR interval
QRS
P wave < 0.10
PR = 0.12 - 0.20
QRS = < 0.12
ST depression or elevation > 0.5mm is a concern
Total Cholesterol
This is the sum of HDL, LDL and VLDL
Desirable levels are >200mg/dL (<5.2mmol/L)
HDL (high-density lipoprotein)
“Good cholesterol”
Binds with fat from the body in the bloodstream and carries it to the liver
May confer anti inflammatory and antioxidant benefits on the arterial wall (Barter, 2004)
HDL levels are generally higher in women
Exercise and smoking cessation can help raise HDL levels (Scruth & Haynes, 2011)
Desirable level >40mg/dL (<1.00mmol/L)
LDL (low-density lipoprotein)
“Bad cholesterol”
Carries fat from the liver to other parts of the body
High levels are associated with increased risk of coronary artery disease, peripheral artery disease and stroke.
Desirable level <2.00mmol/L)
VLDL: (very low-density lipoprotein)
Primary carrier of triglycerides in the blood
Distributes the triglycerides produced by the liver, then is reduced to LDL
Not usually mentioned during routine cholesterol screening, as there is no direct way to measure it. Its value is estimated as a percentage of the triglyceride level.
Desirable level <1.67mmol/L)
Triglycerides
Carried by VLDL
High triglyceride level along with a high LDL cholesterol increases risk for CAD more than having a high LDL cholesterol level alone.
Desirable level <1.7mmol/L)
Antihypertensive medications
diuretics, beta-blockers ACE inhibitors, angiotensin II receptor blockers Calcium antagonists
SAMPLE history
Signs and Symptoms
Allergies
Medications
Past medical history, injuries, illnesses
Last meal/intake
Events leading up to the injury and/or illness
CARDIAC history
Chest pain Ankle swilling Reduced exercise tolerance Dysnpoea, orthopnea Irregular heart beat and palpitations Altered colour of lips or cyanosis Conciousness reduced or LOC
PQRST
Preceding events Quality Radiating Severity Time
Cardiac enzymes
Creatine kinase (CK),
Creatine kinase–myocardial band isofraction (CK-MB), Troponin I
Troponinin II
S/S of MI
Sudden chest pain or discomfort, palpitations
Heart sound may include S3 , S4
Tachycardia, bradycardia, or dysrhythmias
Shortness of breath, dyspnea, tachypnea,
Nausea and vomiting; Indigestion
Anxiety, restlessness, light-headedness
Cool, pale, and moist skin
Patient history of presenting symptoms and previous illnesses, and family history of heart
Pharmacology for MI
fibirinolytic therapy: alteplase, reteplase, or tenecteplase, as fibrinolytic therapy,
infusion of heparin or enoxaparin, as antithrombotic therapy to prevent rethrombosis,
clopidogrel to inhibit platelet aggregation
beta-blocker to prevent ventricular arrhythmias and ischemia;
nitroglycerin for angina;
atorvastatin to reduce cholesterol levels;
alprazolam for anxiety; and
morphine sulfate for pain
