Coronary and pulmonary circulation Flashcards
most transmural MIs occur in what areas of the heart?
anterior LV
inferior LV
in which leads are anterior LV transmural MIs best seen?
precordial leads
lead I
aVL
in which leads are inferior LV transmural MIs best seen?
lead II
lead III
aVF
changes in the ECG at the
precordial leads
lead I
aVL
indicate an MI in which area of the heart?
anterior LV
changes in the ECG at the
lead II
lead III
aVF
indicate an MI in which area of the heart?
inferior LV
the heart is perfused primarily during what phase of the cardiac cycle?
ventricular diastole (rapid filling)
as LV pressure decrease, what happens to blood flow?
decrease
why is phasic blood flow of coronary circulation less pronounced on the right side?
less pressure (to open pulmonic valve)
what is the relationship of flow and pressure in coronary circulation?
flow = change in pressure / resistance
when is the change in aortic pressure lowest?
isovolumic contraction
definition: myogenic autoregulation
being able to actively maintain a constant blood flow
intrinsic mechanism of vascular smooth muscle cells
definition: coronary reserve
what is it related to?
difference between autoregulation and actual vasodilatory capacity of the vessels
related to how well the vessels can open and close (vasodilate) in response to incoming pressure
what are the metabolic steps of oxygen regulation?
increased metabolism increased hypoxia increased ATP turnover increased cellular adenosine accumulation vasodilation
what are the two phases of sympathetic regulation in coronary circulation?
- transient vasoconstriction due to direct action of NE on alpha receptors
- increased force of contraction and HR (metabolic vasodilation)
hypoxis elicits what response in the coronary vasculature? what mediates this response?
vasodilation
adenosine
what are the passive regulatory mechanisms for pulmonary blood flow through the circuit?
- recruitment - opening of previously closed capillaries
- distension - accommodation of increased blood volume
- gravity, position, lung volume, alveolar and intrapleural pressure, intravascular pressures, RV output
what are the active regulatory mechanisms for pulmonary blood flow through the circuit?
- hypoxic vasoconstriction
2. other metabolites
what is the effect of hypoxia on vasculature in the lungs?
vasoconstriction
what is the rationale for pulmonary vasoconstriction in response to hypoxia?
blood is diverted to better ventilated alveoli - maintains V:Q matching
what occurs in the late stages of pulmonary artery hypertension?
failing (right) heart can no longer generate enough pressure to maintain CO
what occurs in the early stages of pulmonary artery hypertension?
CO is initially compensated by neuronal and humoral factors - contributes to further increases in PAP
