Anatomy, physiology, hemodynamics Flashcards
What does the right coronary artery supply?
-RV
-SA and AV nodes
-posterior and inferior surfaces of the LV
What makes up the left coronary system?
Circumflex and LAD
What does the left coronary artery supply?
-IV septum
-conduction system below the AV node
-anterior and lateral LV walls
What determines end diastolic volume?
Ventricular compliance and transmural pressure
By what mechanisms can diastolic compliance be reduced?
-myocardial thickening/dysfunction (MI, HTN, valve dysfunction)
-pericardial disease (tamponade)
-extrinsic compression (PEEP, TPTX, RV dilation, impaired chest wall compliance)
What is one common consequence of sudden diastolic dysfunction?
Flash pulmonary edema
In diastolic dysfunction what does ventricular filling become dependent on?
Terminal-phase atrial contraction (“atrial kick”)
Definition of afterload?
Muscular tension that must be developed during systolic per unit of blood flow
How does a normal heart accommodate for changes in afterload?
Increases in:
-contractility
-preload
-heart rate
What happens if preload reserves have been exhausted but there is still a rising/elevated afterload?
Cardiac output depression
Which ventricle is more sensitive to increasing afterload?
RV
What can influence contractility independent of preload or afterload?
-sympathetic impulses
-circulating catecholamines
-acid/base and electrolyte disturbances
-ischemia
-anoxia
-chemodepressants
-hormones (high dose insulin)
What is the equation to grossly predict the maximum atrial rate before cardiac output and myocardial perfusion are reduced?
(220 - age)/min1
What is the basic definition of CHF?
Condition in which the filing pressures of the left heart are increased enough to cause dyspnea or weakness at rest or mild exertion
Is a normal functioning LV sensitive or not sensitive to afterload? How about a failing LV?
-normal LV is insensitive to changes in afterload but sensitive to preload
-failing LV is sensitive to afterload and fairly insensitive to preload
What are some radiologic findings that suggest acute heart failure?
-perivascular cuffing
-widened perivascular pedicle
-blurring of the hilar vasculature
-diffuse infiltrates
How do infiltrates in acute heart failure differ from those found in ARDS and PNA?
AHF infiltrates lack air bronchograms and are usually unaccompanied by an acute change in heart size
What are some radiologic findings that suggest chronic heart failure?
-Kerley B lines
-dilated cardiac chambers
-increased cardiac dimensions
What are the 2 endogenous natriuretic peptides are released in response to myocardial stretch (ie. ventricular overload)?
-ANP atrial natriuretic peptide
-BNP B-type natriuretic peptide
What effects on other endogenous peptides do cardiac natriuretic peptides have?
-lower excessive levels of angiotension 2
-lowers aldosterone
-lowers endothelial 1
What systemic effects do cardiac natriuretic peptide have?
-arterial and venous dilation
-enhanced diuresis
-inhibition of sodium reabsorption
Which cardiac natriuretic peptide is only stored in small amounts in ventricular granules so an increase is more indicative of ventricular dysfunction and myocardial stretch?
BNP
Other than myocardial stretch what else can cause BNP elevation?
-lung diseases
-renal insufficiency
-sepsis
-inflammatory states
What are potential causes of LV insufficiency CHF with normal LV cavity size?
-mitral stenosis
-tamponade
-constrictive pericarditis
-acute myocardial infarction
-hypertrophic cardiomyopathy
-diastolic dysfunction
What had the signature echo findings of apical ballooning with preserved ballast basilar contraction?
Takotsubo cardiomyopathy (stress cardiomyopathy)
-these findings are temporary
What does generalized hypokinesis with normal chamber size on echo reflect and what causes it?
Stunned myocardium
-trauma
-diffuse ischemia
-drug overdose
-toxin ingestion
-post-tachycardia dysfunction
What should be used in CHF with LV insufficiency when there is elevated SVR and/or valvular insufficiency with adequate preload and BP?
ACE inhibitors (captopril, enalapril) and/or systemic vasodilators
What medication can help aid in CHF with LV insufficiency with cardiac ischemia?
Nitrates
-but can precipitate hypotension in patients with borderline or inadequate filling pressures
What is nesiritide?
Recombinant human BNP
-for acutely decompensated CHF w/ dyspnea at rest/minimal exertion
-affects: vasodilation, diuresis, natriuresis, decreases plasma NE and aldosterone, decreases preload
-does not change heart rate
-SE: profound hypotension, bradycardia, renal dysfunction
Most CHF with RV dysfunction arise from which disease conditions?
-ischemia
-infarction
-cor pulmonale
-ARDS
Where does the RV get its blood supply from?
RCA
What type of MI typically leads to RV dysfunction?
Seen in 30% of inferior MIs
When should RV dysfunction from a MI be suspected?
Systemic venous HTN and ST segment elevation or Q waves over right precordium (V4R)
For MI with subsequent RV dysfunction what does prognosis depend on?
-size of infarct
-presence or absence of increased PVR
What are 3 causes of pulmonary hypertension?
-restricted capillary bed
-alveolar hypoxia
-acidosis
What is the maximum pulmonary arterial pressure that normal RVs can overcome?
35mmHg