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
Myoglobin (MB)
- Specificity: Low
- Detectable: 3 Hours
- Peak Levels: 4-9 Hours
Posterior MI
- LCX
- Elevation V8-V9
- Reciprocal Changes V1-V4
- ST depression predominantly in V1-V2
Anterior MI
- LAD
- ST changes V2-V4
Inferior MI
- RCA
- ST Changes in II, III, aVF
- Papillary muscle dysfunction
- Get a right sided - V4R
- Can cause bradycardia, AV blocks
- No NTG or Beta-blockers
Lateral MI
- LCX
- Lateral/Posterior Wall ST segment changes in I, aVL, V5-V6
Anteroseptal MI
- LAD
- ST changes in V1-V4
- LV and septum affected
- papillary muscle dysfunction - cardiogenic shock
Bundle Branch Blocks
- Caused by a defect in electrical impulse
- Widened QRS > 0.12s
- Look at V1 for changes - turn signal rule
Standard AMI Treatment
- Reduce Pre-load/Pain
- Reduce HR/O2 demand (Beta-blockers, CCBs)
- Clot Prevention (ASA)
- Reperfusion (chemical or surgical)
Beta Blockers in MI
REduces HR, thus reducing O2 demand. DO NOT use in bi-fascular blocks or BBB
Heparin/Low Molecular Weight Heparin
Prevents fibrinogen conversion to fibrin to decrease clot formation in the coronary arteries.
Angiotensin Converting Enzyme Inhibitors
Prevents ventricular remodeling in the post-MI patient (keeps heart muscle from growint too much to make up for the lost tissue from the MI)
NAVEL for ETT Meds
Naloxone
Atropine
Vasopressin
Epinephrine
Lidocaine
Class I Antidysrhythmics
- Sodium Channel Blockers
- Lidocaine, Phenytoin, Procainamide
- Interferes with Na+ channels
Class II Antidysrhythmics
- Beta blockers
- Carvedilol, labetalol, propranolol, timolol, esmolol, metoprolol
- Anti-sympathetic nervous system agnts
- Reduce heart rate, reduce cardiac oxygen demand
Class III Antidysrhythmics
- Miscellaneous
- Amiodarone
- Affects K+ efflux
Class IV Antidysrhythmics
- Calcium Channel Blockers (CCBs)
- Verapamil, diltiazem
- Affects the AV node
Class V Antidysrhythmics
- Other
- Adenosine, digoxin, MgSO4
- Works by “other” mechanism - no good way to classify/stratify
Neurovascular System Effects
- Alpha-1 - vasoconstrict
- Beta-1 - increase heart rate, contractility
- Beta-2 - dilate bronchioles/blood vessels
- Dopaminergic - gut kidney vessel dilation
- Cholinergic - decrease heart rate
Fibrinolytic Indications
- Clinical presentation of AMI w/in 12hrs of Sx onset
- EKG showing STEMI or new onset LBBB
- Absence of contraindications
- Absence of cardiogenic shock
Fibrinolytic Absolute CI
- Prior Intracranial Hemorrhage
- Known structural cerebral vascular lesion
- Known malignant intracranial neoplasm
- Ischemic stroke within 3 months
- Suspected aortic dissection
- Active bleeding or bleeding diathesis
- Significant closed-head/facial trauma within 3 months
PCTA
Percutaneous Trans-Luminal Coronary Angioplasty
- Administer GP2B3A Inhibitors
- Keep leg straight during transport and hold direct pressure for 30min post cath
Glycoprotein-2B3A Inhibitors
Prevents platelet activity. Can be titrated and have a half-life of about 8 hours. Examples - Reopro, Integrilin, Aggrastat
CABG
Coronary Artery Bypass Graft
- RCA - repaired using the sapneous vein
- LAD - repaired using the inferior mammary artery
Angina
Stable - lasting 1-5min and releived by NTG and rest. Predictable course
Prinzmetals Angina
- Chest pain at rest, has a circadian rhythm (often early AM)
- Most often seen in women
- Treated with NTG and CCBs
Silent Angina
No pain but evidence of ischemia on EKG (ST depression)
Heart Transplant
- Decompensation = immediate cardioversion
- Dopamine and NSS bolus in setting of bradycardia
- Can also use neosynephrine
Wolff-Parkinson-White Syndrome (WPW)
- Extra electrical circuit in the heart, causes tachycardia
- Common cause of tachycardia in infants/children
- Treated by surgical ablation of the aberrant pathway
- Causes a delta wave on EKG
Endocarditis
- Inflammation or infection inside the heart
- Sudden onset with new murmur
- # 1 cause is IV drug abuse
- Osler Nodes (painful red fingertips)
- Janeway Lesions (red lesions on palm and soles)
Pericarditis
- Inflammation or infection on the outside of the heart
- Substernal chest pain when breathing or laying supine (pericardium rubs against the sternum)
- 80% have idiopathic cause
- Global ST elevation, round T waves
- Treated with NSAIDs (usually Indocin)
- Colchicine becoming treatment of choice
Uremic Pericarditis
Can be seen in a patient that is undergoing dialysis because they are in renal failure.
Dressler’s Syndrome
Pericarditis occurring in the post MI/post cardiac surgery patient
Congestive Heart Failure (CHF)
- Progressive dyspnea, frosthy sputum
- CXR Findings - butterfly/Kerley B lines, bilateral diffuse infiltrates
- Heart >50% width of chest
- BNP elevated
- Tx - CPAP and Nitrates, ACE inhibitors, Beta-blockers, ? lasix
B-Type Natriuretic Peptide (BNP)
- BNP released by the ventricles in response to stretching and causes diuresis, reducing preload and afterload
- Natrecor (Nesiritide) is synthetic BNP
- < 100 pg/mL = no heart failure
- > 300 pg/mL = mild heart failure
- > 600 pg/mL = moderate heart failure
- > 900 pg/mL = severe heart failure
Aortic Dissection
- Ripping or tearing sensation between shoulder blades
- Can also present in chest/abdomen
- Common in Marfan’s syndrome
- Ascending aorta most common site
- CXR Findings - widened mediastinum, loss of aortic knob, pleural effusion
- Difference in 20mmHg SBP between arms is common
Aortic Aneurysm
- Out pouching of either the cardiac or abdominal aorta
- Typically found on routine CT or during physical exam
- Surgical repair when >5cm or symptomatic
