case 3 - CHF Flashcards
What are possible etiologies for dilated cardiomyopathy?
- genetic or acquired
- if acquired, can be inflammatory and noninflammatory forms.
Acquired, inflammatory
- infection or parsitic infection -> myocarditis -> CHF
- associated palpitations progress to overt CHF with cardiac dilation, tachy, pulsus alternans, pulm edema
- chagas or diptheria disease
- viral infections
acquired, noninflammatory
- alcohol
- direct toxic effects of ethanol or acetaldehyde –> release and deplete cardiac norepi stores
- doxarubicin
- amyloidosis -> myocardial infiltration -> obstructive and restrictive forms of cardiomyopathy
what is dilated cardiomyopathy defined as?
ventricular chamber enlargement (inc radius) and systolic dysfunction with normal LV wall thickness
what is the pathophysiology behind dilated cardiomyopathy?
In order:
- ventricle experiences decreased contractility
- ventricular muscle weakness from insult
- ventricle dilates to increase contractility
- increase myocardial fiber length results in increased force of contraction (frank starling)
- increase ventricular radius results in inc wall tension
- laplace law T = (P x R) / 2 H
- inc wall tension -> inc o2 consumption and inc cardiac work
- CO falls
- RAA and inc sympathetic stimulation: HR & SVR
- HR and SVR increased to maintain MAP
- increased afterload decreases stroke volume -> reduce CO -> backflow of blood into pulm circulation
Why is afterload reduction important in dilated cardiomyopathy patients?
- normal hearts can maintain stroke volume in face of increase afterload
- LV dysfunction worsens in cardiomyopathy
-
failing myocardium cannot maintain SV against elevated afterload
- not enough contractile strength
- result is inc LVEDP due to dec SV, backflow of blood into LA, into pulm circulation
-
failing myocardium cannot maintain SV against elevated afterload
-
afterload reduction allows forward flow of blood
- stroke volume decreases lineraly with increase in afterload
- afterload reduction reduces LVEDP -> inc CPP
Manifestations of ventricular failure can be though of as forward flow and backward flow failure. Describe manifestations of both?
dilated cardiomyopathy (DCM) can have forward failure and backward failure
Forward Failure - diminished CO and organ perfusion
- fatigue
- hypotension
- oliguria
- activation of R-A-A system
backward failure - LVEDP and functional MR
- dilated ventricle and inc LVEDP results in secondary mitral regurg and annulus separates from each other
- Left Sided CHF
- orthopnea
- paroxysmal noctural dyspnea
- pulm edema
- R sided CHF
- JVD
- peripheral edema
- hepatomegaly
What is the difference between orthopnea and PND?
PND
- Paroxysmal nocturnal dyspnea occurs at night
- defined as the sudden awakening of the patient, after a couple of hours of sleep, with a feeling of severe anxiety, breathlessness, and suffocation
- In contrast to orthopnea, which may be relieved by immediately sitting up in bed, paroxysmal nocturnal dyspnea may require 30 minutes or longer in this position for relief
Orthopnea
dyspnea that develops in the recumbent position and is relieved with elevation of the head with pillows.
what is the mechanism of action behind ortopnea and PND?
- failing LV is operating on the flat portion of the Frank-Starling curve
- in recumbent position, blood shifts from lower extremity to heart -> inc venous return
- LV cannot accept and pump out the extra volume of blood delivered to it without dilating.
- As a result, pulmonary venous and capillary pressures rise further, causing interstitial pulmonary edema, reduced pulmonary compliance, increased airway resistance, and dyspnea.
what monitors would you place on a patient with a low EF secondary to dilated cardiomyopathy who is undergoing surgery?
1) EKG
- detect ischemia (lead II and V5)
- especially if CAD is casue of DCM
- DCM associated with arrhythmias including complete heart block
2) a-line
- beat to beat monitoring
- obtain ABG
- avoid increaes in afterload
- pre-induction
3) CVC
- monitor right side pressure
- epsecially in left side CHF patients, cor pulmonale, pulm HTN
- administer vasoactive medication
- poor IV access
4) PAC/TEE
what would be the value of PAC or TEE in a patient with low EF 2/2 dilated cardiomyopathy undergoing elective surgery?
PAC
-
valuable in pts with compromised LV function
- measure left side pressures (PCWP, Pulm A diastolic)
- measure right side filling pressure (pulm HTN, cor pulmonale, left side CHF)
- thermodilution CO
- allow for serial eval of HD status
- calculate SVR, PVR
- SVO2
- transvenous pacing
TEE
- assess RV and LV function
- real time feed
- inotropic or vasodilator support needed?
- transgatric short axis -> assess RWMA in coronary artery territory
- preload adequate?
- MR getting worse? degree of MR
- functional MR 2/2 dilated cardiomyopathy separating mitral annulus from each other
What are your hemodynamic goals in patients with DCM?
HR, preload, afterload, contracility
1) HR - normal to elevated
- indicated - dopamine or dobuatmine
- dopamine is highly arrhythmogenic
- avoid high dose BB
2) preload - normal to high
- indicated - IV Fluids
- avoid NTG, propofol, thiopental
3) Afterload - Low
- indicated - ACE-I, SNP, Milrinone
- avoid phenylephrine
4) contractility - increased
- indicated - dopa, dobuta, epi, milrinone
- avoid high dose volatile anes, N2O, high dose BB
how would you induce this patient with low EF undergoing elective surgery? What is your anesthesia mainteance plan?
HD Goals:
- HR (normal to elevated)
- preload (normal to high)
- afterload (low)
- contractility (increased)
Induction
- Ketamine or Etomidate
- HD stable
- propofol assoc with myocard depression and dec venous return 2/2 venous dilation
Maintenance
- low dose volatile anesthetic + opioid infusion
- low dose volatile anesthetic + N2O + opioid infusion
-
goal: avoid myocardial depression -
- high dose vol anes or high dose propofol
are you concerned about arrythmias developing intra-op in DCM pts? What would you have ready to tx arrythmias?
YES
- DCM have SVT and ventricular arrythmias.
- EF < 30% pts have ICDs
- high risk for intraop arrythmias
ICD mgmt
- pts typically have ICD-PPM
- turn off tachy therapy
- place external defib pads on patients
Pharmalogical meds for arrythmias
- esmolol
- amiodarone
Electrical
-
external defib pads
- for defbrillation or sync cardiovert
- transcuatenous or transvenous pacing
Can you consider regional anes?
For lower extremity procedures you can consider regional
- follow a/c guidelines
- pts typically can have a-fib or mural thrombus prevention due to LA dilation 2/2 DCM
- adequately monitor HD effects
