Solution-Why an increase in constriction of veins
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April 26, 2020Solution-Why an increase in constriction of veins
1. Why 60 years-old patient HA, who was bedridden for a few days, feels dizzy and experiences significant increase in his heart rate after standing up?
2. What will happen to his systemic arterioles regarding vascular tone changes?
3. Why an increase in constriction of veins and an increase in venous return will help to increase his end-diastolic volume?
4. How did epinephrine release from his adrenal medulla affect his blood supply (perfusion) to his skeletal muscles?
5. If this patient is regularly taking beta-blocker, such as metoprolol, how will this drug affect his sympathetic discharge to the heart, to veins and to arterioles? What changes in his blood pressure can be expected? What advice should be given to this patient?
6. If this patient is regularly taking vasodilator, such as long-acting isosorbidedinitrate (Isordil), how will this drug affect his sympathetic discharge to the heart, to veins and to arterioles? What changes in his blood pressure can be expected? What advice should be given to this patient?
7. If this patient is regularly taking Calcium Channel Blocker (CCB), such as nifedipine, how will this drug affect his sympathetic discharge to the heart, to veins and to arterioles? What changes in his blood pressure can be expected? What advice should be given to this patient?
8. If this patient is regularly taking Angiotensin Converting Enzyme (ACE) inhibitor, such as lisinopril, how will this drug affect his sympathetic discharge to the heart, to veins and to arterioles? What changes in his blood pressure can be expected? What advice should be given to this patient?
9. If this patient is regularly taking Angiotensin Receptor Blocker (ARB), such as losartan, how will this drug affect his sympathetic discharge to the heart, to veins and to arterioles? What changes in his blood pressure can be expected? What advice should be given to this patient?
10. If this patient is regularly taking thiazide diuretic, such as hydrochlorothiazide, how will this drug affect his sympathetic discharge to the heart, to veins and to arterioles? What changes in his blood pressure can be expected? What advice should be given to this patient?
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ß blocker such as metoprolol are selectively potent against cardiac (ß1) compared to bronchial (ß2) receptors, however this selectivity is lost at higher dose. The sympathetic discharge of the heart is reduced with various protective mechanism such as (i) sub-endocardial coronary flow enhancement, which leads to diastolic prolongation; (ii) restoration of reflex control over heart and circulation; (iii) inhibition of catecholamine cardiotoxic effects and (iv) improved myocardial performance with reduction in heart rate and oxygen demand.
It is noteworthy to mention that the chronic usage of ß blocker – metoprolol is likely to improve the performance of left ventricle and reverses the left ventricle remodeling. The oxygen supply to the myocardial is improved, which also increases the exercise tolerance. These condition leads to improved patient ß blocker such as metoprolol are selectively potent against cardiac (ß1) compared to bronchial (ß2) receptors, however this selectivity is lost at higher dose. The sympathetic discharge of the heart is reduced with various
