Cardiac Flashcards
This ion is the primary determinant of RMP
K+
Because it continuously leaks from the cell and contribute to it’s negative internal charge
Number of Na and K ions moved by the Na/K pump?
3Na out
2K in
Moving more positive charges OUT contributes to restoring internal negative charge
What is the purpose of the plateau in the myocyte AP?
To give the myocytes time to contract so the heart has enough time to eject it’s SV
This artery supplies the SA node
Posterior descending
That’s why this artery determines is the circulation is R or L dominant!
Cardiac veins and their arterial pairs
Great cardiac vein (LAD)
Anterior cardiac vein (RCA)
Middle cardiac vein (PDA)
Coronary blood flow is auto regulated over these MAPs
60-120
Oxygen extraction ratio in the heart
70%
When do most peri-op MIs occur?
1-2 days after surgery
20% mortality
Normal and pathologic valve sizes
Aortic = 2.5-3.5cm2 (
Most common causes of AS
1) Bicuspid valve
2) Calcifications
3) Rheumatic fever, infective endocarditis, etc.
Classic triad of AS
It’s a SAD triad
- Syncope
- Angine
- Dyspnea
Why should you listen to the heart before performing a spinal in the elderly?
Listen to the right sternal border for the Aortic valve. Murmur could indicate undiagnosed AS.
Anesthetic management of AS
- NSR with HR 70-80
- Increase preload (more volume needed to ffill noncompliant ventricle)
- Maintain or increase SVR
- Maintain contractility
- Keep PVR normal
- Avoid spinals if severe AS
What is afterload in AS?
It’s set by the degree of aortic stenosis.
This is the afterload that the heart needs to pump against and is why we’re not worried about increasing SVR. In fact, we want to increase SVR to increase CPP.
Common causes of mitral stenosis in the US
Endocarditis and atherosclerosis
These chronic conditions result in increased ventricular compliance
Dilated cardiomyopathy and aortic regurgitation
2 hallmarks of systolic HF are
1) Decreased EF
2) Increased EDV
VOLUME OVERLOAD leads to systolic dysfunction
Hallmark of diastolic HF
S/S of HF but a normal EF
Chronic pumping against high pressure leads to concentric hypertrophy and diastolic dysfunction
What is the most common cause of RHF?
LHF
These two things will decrease oxygen extraction in the heart
1) Decreased P50
2) Decreased capillary density
Why are CCBs good during MI?
They optimize the balance between O2 supply and demand by:
- Decreasing contractility
- Vasodilating the coronaries
- Decreasing SA firing rate
- Decrease AV conduction
- Decrease after load via systemic vasodilation
The effects of CCBs vary widely, so some are better for certain things than others.
Which are best for HR control, contractility control, and control of vascular tone?
HR
- Diltiazem and verapamil (VeRAPIDamil)
Control of contractility:
- V > N > D > Nic
- Verapamil > Nifedipine > Diltiazem > Nicardipine
- If pt has low EF and you need to slow HR, diltiazem would be a better choice than verapamil
Control of vascular tone:
- Nifedipine, amlodipine, and nicardipine
- Nicardipine is good as a coronary antispasmodic
Times you need to wait after PCI for an elective surgery
Balloon angioplasty = 2-4 weeks
Bare metal stent = 6-12 weeks (12 preferred)
CABG = 6-12 weeks (12 preferred)
Drug eluting stent = 1 year
When to stop ASA, plavix, and ticlopidine before surgery
ASA
- Can continue through periop period, unless contraindicated by type of surgery
- If contraindicated, stop at least 3 days prior
Plavix = 7 days
Ticlopidine = 14 days
Should heparin to LMWH be used to bridge stopped antiplatelets before surgery?
NO
These meds can actually INCREASE platelet activity
Which is worse? Constrictive pericarditis, or acute pericarditis?
Constrictive
Acute is usually viral in nature, self limiting, and usually does NOT impair diastolic function.
No special anesthesia considerations for acute viral.
Beck’s Triad of pericardial tamponade
1) Muffled heart tones
2) JVD
3) Hypotension
CVP in pericardial tamponade
CVP rises in tandem with increased pericardial pressures
What is Kussmaul’s sign?
Increased CVP and JVD with inspiration
Occurs with pericardial tamponade
What is pulses paradoxus?
Decrease in SBP by > 10mmHg on inspiration
Who is at risk for infective endocarditis?
- Previous IE
- Prosthetic heart valve
- Unprepared cyanotic congenital heart disease
- Repaired congenital heart defect if repair is
For what surgical procedures are people at risk of developing infective endocarditis?
1) Dental procedures
2) Respiratory procedures that involve incision or biopsy
3) Biopsy of infective lesions on skin or muscle
Other names for obstructive hypertrophic cardiomyopathy (OHCM)
1) Hypertrophic obstructive cardiomyopathy (HOCM)
2) Asymmetrical septal hypertrophy (ASH)
3) Idiopathic hypertrophic subaortic stenosis (IHSS)
Patho of OHCM/IHSS
2 things that result in LVOT obstruction:
- Congenital hypertrophy of the interventricular septum
- Anterior motion of the anterior leaflet of mitral valve during systole
When the ventricle contracts FORCEFULLY, the anterior leaflet is MORE likely to reduce flow
Goals for those with IHSS
Problem is LVOT obstruction which is worsened with forceful contraction. So we want to dilate the LVOT and decrease force of contraction
- Increase LV volume by increasing preload or decreasing HR
- Decrease contractility
- Increase aortic pressure (increased pressure within ventricle to push past it dilates the LVOT)
Contraindications for an aortic balloon pump
1) Severe aortic regurgitation
2) Sepsis
3) Severe PVD
4) Descending aortic disease
This is the most common cause of secondary HTN
Renal artery stenosis
Does venous return increase or decrease with aortic cross clamp (AoX) placement?
Increases, because blood volume shifts proximal to the clamp. Basically, same blood volume within smaller amount of vasculature
Why is the artery of Adamkiewicz so important?
Because the thoracolumbar spine is highly dependent on radicular arteries for perfusion
AoX and the artery of Adamkiewicz
AoX placed ABOVE this artery can cause ischemia to the anterior portion of the lower spinal cord.
This will result in anterior spinal artery syndrome (Beck’s Syndrome)
S/S of Beck’s syndrome
Caused by AoX proximal to artery of Adamkiewicz
- Flaccid paralysis of lower extremities
- Bowel and bladder dysfunction
- Loss of temperature and pain sensation
- Touch and proprioception remain INTACT
