Critical Care Cardiology Flashcards
Cardiac Output (CO)
Heart Rate x Stroke Volume
(Typically 4-8L/min)
Stroke Volume (SV)
Amount of blood ejected from the heart with each ventricular contraction. Affected by preload, contractility, and afterload.
Preload
The load that stretches the cardiac tissue before contraction.
Contractility
The intrinsit ability of the heart/myocardium to contract
Frank-Starling Law
The stroke volume of the heart increases in response to an increase in the volume of blood filling the heart. Increased volume stretches the ventricular wall causing the muscle to contract more forcefully.
Afterload
The degree of vascular resistance to ventricular contraction. Right heart is affected by pulmonary vascular resistance, left heart by systemic vascular resistance.
Pulmonary Vascular Resistance (PVR)
- Measures afterload of the right heart
- Normal = 50-250 dynes
- Increased: Acidosis, hypercapnia, hypoxia, atelectasis, ARDS
- Decreased: Alkalosis, hypocapnea, vasodilating drugs
Systemic Vascular Resistance (SVR)
- Measures afterload of the left heart
- Normal = 800-1200 dynes
- Increased: Hypothermia, hypovolemic shock, decreased CO
- Decreased: Anaphylaxis, neurogenic shock, septic shock, vasodilating drugs
S1 Heart Sound
“Lub”
Bicuspd/tricuspid valve closure.
S2 Heart Sound
“Dub”
Aortic/pulmonic valve closure.
S3 Heart Sound
“Kentucky”
- Excessive filling of the ventricles
- CHF, chordae tendinae dysfunction
S4 Heart Sound
“Tennessee”
- Blood being forced into a stiff (non-compliant) ventricle
- Causes: Hypertrophic cardiomyopathy, HTN
- Associated with MI!!!
PMAT Mnemonic
Heart Sound Ausculation Points
- Pulmonary
- Mitral
- Aortic
- Tricuspid
Right Coronary Artery (RCA)
- Supplies the RV and in most of the population the SA node
- Inferior MI
- Bradycardia due to SA node involvement
Posterior Descending Artery (PDA)
- Branch off of the RCA
- Inferior Wall
- Ventricular Septum
- Papillary Muscles
Left Coronary Artery (LCA)
A complete block is called the “widow maker” because it occludes both the LAD and LCX.
Left Anterior Descending (LAD)
- Supplies anterior left ventricle/anterior septum
- Anterior MI/septal MI/Anteroseptal MI
Left Circumflex (LCX)
- Somtimes called the “circumflex artery”
- Supplies lateral left ventricle/posterior left ventricle in 45% of population
- Lateral MI/Posterior MI
STEMI Criteria
- ST elevation in 2 continuous leads > 1mm
- Cardiac death “happening now”
- Often associated with new onset LBBB
- cardiac markers/enzymes
NSTEMI
- ST depression of dynamic T wave changes in 2 contiguous leads
- ST depression caused by lack of O2 to cardiac tissue
- cardiac markers/enzymes
Unstable Angina (UA)
- Angina that is not relieved by rest, nitro, or is different quality than patient’s normal chest pain
- May have ST segment depression
Cardiac Panel
(Typically)
Troponin I
CK-MB
MB
Troponin I
- Specificity: High
- Detectable: 2 Hours
- Peak Level: 12 hours
Creatinine Kinase Myoglobin (CK-MB)
- Specificity: Moderate
- Detectable: 4-8 Hours
- Peak Level: 12-24 Hours