Valves Flashcards
Drug therapy for valvular disease
- Digitalis (Digoxin) - Given to increase contractility and slow the ventricular rate in those with a-fib
- Diuretics - May be given for excess intravascular fluid volume, but resultant hypokalemia can place at risk for digitalis toxicity
- Prophylactic Antibiotics - Recommended for the protection against the development of sub-acute bacterial endocarditis
Tests for valvular heart disease? what will they tell us?
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Doppler Echo -
- valve movement, flow and pressure gradients
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Cardiac cath
- measure the severity of valvular heart disease
- valve movement, flow and pressure gradients
- ABG→decreased PaO2 and V/Q mismatch
Pathophysiology of mitral stenosis
- Most common in females
- Primary cause = rheumatic fever (slow development over 20-30 years)
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Valvular manifestations:
- fusion of mitral valve leaflets at the commisures
- calcification of annulus an leaflets
- Senosis with a valve 2 (normal 4-6cm2) need 25 mmHg to generate adequate cardiac output
- Stenosis over time will lead to
- Left atrial enlargement
- Pulm HTN
- RV enlargement and RF failure
What are some complications associated with Left atrial enlargement?
- Left atrial enlargement - Predisposes to a-fib
- A-fib→stasis and development of thrombi
- Anticoagulants are needed
Severe Mitral stenosis can lead to
CHF
Mitral Stenosis
Anesthetic Management GOALS
SLOW, TIGHT, and FULL → prevention and treatment of events that decrease CO or cause pulmonary edema
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Slow HR 50-60:
- Avoid tachycardia or a-fib with RVR (both decreases CO and cases pulmonary edema d/t increased RA pressure)
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Tight controll of blood volume:
- Tight fluid administration, give blood or colloids.
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Full:
- manitain preload→avoid marked increases in blood volume from over-transfusion or head-down positions →still need adequate pressures to overcome the stenosed valve.
- Maintain afterload →Large decreases in SVR will drop preload. More importantly - the compensation for decreased SVR→baroreceptor reflex→increases HR which will generate a LOW CO in this patient! (avoid NTG, and hgh MAC techniques→IAs will drop SVR).
- Manitain full contractility
(also avoid arterial hypoxemia/hypoventilation that may exacerbate PulmHTN→leading to right ventricualr failure)
Induction for MITRAL STENOSIS pharmacologic considerations
- Etomidate is ideal (if you must use propoflol use it with phenylephrine, also give esmolol prior to DVL)
- Goal = ventricular rate controll!
- USE: ß-blockers, CCB
- AVOID: tachycardia →decreases left ventricualr filling and increases left atrial pressure! a drop in SV
- AVOID things that increase HR→ NO KETAMINE, No anticholinergics (glyco or atropine), histamine releasing drugs
- AVOID things that abruptly decrease SVR→ Better to chose a high opioid techniqe over IAs , Propofol, NTG
- USE: Phenylephrine (pure vasoconstrictor) and Vasopressin (does NOT effect the pulmonary vasculature) to treat/avoid decreased SVR
- Possiblly avoid nitrous → it increases pulmonary vascular resistance which may potentiate pulmonary edema
- Desflurane → not a good choice it decreases SVR and causes increased HR and BP transiently when increased - ISO = slow ∆ abd time for body to adapt
Patho of mitral regurgitation
- Usually d/t rheumatic fever and is almost always associated with mitral stenosis.
- Causes decreased forward LV Stroke volume and retrograde flow during ventricular contraction - resulting in LA fluid volume overload
- Can be caused by RA, MI, ruptured chordae tendonae, ischemia to the papillary muscles, congenital disorders
Appearance of mitral regurgitation:
- On PCWP tracing
- x-Ray
- EKG
- Reguritant flow = V wave on PCWP tracing
- (Size of the V wave correlates with the magnitude of regurgitant flow)
- X-ray shows cardiomegaly
- (eccentric hypertrophy over time to compensate for decreased CO)
- EKG shows Left atrial and left ventricular hypertrophy
- (Atrial = notched broad P wave)
Mitral regurgitation anesthetic management GOALS
Fast, Full, Forward
Goal = improve LV forward stroke volume and decrease the regurgitant fraction:
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Fast HR: (80-100 bpm)
- Avoid sudden decreases in HR - Bradycardia cuases severe LV volume overload and allows more time for blood to flow backwards
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Full tank: Preload remains the same
- Increase = more regurgitaion
- Decrease = Less CO (NTG = bad choice)
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Forward: Decreased/Normal Afterload
- Decreased SVR promotes forward flow
- Nitropruside → decreases afterload and allows for more effective cardiac pumping
- Hydralazine (arterial dialator)
- Regional may be a good choice to decrease SVR
- Avoid: sudden increases in SVR, which would promote backward flow
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Maintain contractility -
- low MAC - balanced techniques - high opioids,
- inotropes
Causes of of aortic stenosis
Associated size and pressure?
- Calcification developed over time (develops around 60-80 years)
- Bicuspid Aortic Valve instead of a Tricuspid Aortic valve (develops around 30-50 years)
- Congenital abnormality
- Rheumatic heart disease or Endocarditis
- Normal valve area is 2.5-3.5cm2. Significant AS is associated with valve area of <1 cm2 and a transvalular gradient of >50mmHg.
Explain the pathology of angina associated with Aortic stenosis
What is the classic symptom triad with Aortic Stenosis
- Angina is often present without CAD
- The specific contributers to angina
- LV concentric hypertrophy increases oxygen requirements
- Increased myocardial work to overcome stenosis
- decreased O2 delivery d/t compression of the subendocardial vessels
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Classic triad = Angina, Dyspnea on Exertion, Syncope
- (75% who are symptomatic will die w/ in 3 years if they do not have a valve replacement!)
Aortic Stenosis anesthetic management GOALS from class
Prevent hypotension and any hemodynamic change that will decrease cardiac output
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MUST Maintain NSR: Low/normal (60-90)→avoid sudden decreases in HR (worse) AND tachycardia
- BP is HR dependent
- Maintain Preload→Optimize intervascular fluid volume to maintain venous return and LV filling
- Maintain Afterload→Avoid sudden decreases in SVR→decreased coronary filling
- Maintain contractility
Induction in a patient with Aortic Stenosis
Method? Drugs?
- GENERAL ANESTHESIA is preferred over regional (because regional causes sympathectomy and drop in SVR)
- Good choice is something that DOES NOT decrease SVR
- Etomidate is best
- High opioid technique if poor LV function
- Etomidate + Benzos
- Propofol + Phenylephrine??
- AVOID: Ketamine - it causes tachycardia
Causes of aortic regurgitation
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Acute:
- Infective endocarditis
- Dissection of thoracic aortic aneurysm
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Chronic
- Rheumatic fever
- Chronic HTN
- Marfans
- idiopathic aortic root dilation
- bicuspid aortic valve