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Cardiovascular physiology.

Cardiovascular physiology. Dr James Ker. 2 scenario`s in cardiology:. Systemic diseases affecting the cardiovascular system. Primary cardiovascular diseases. How can these diseases affect the cadiovascular system ?. Components of the cardiovascular system:

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Cardiovascular physiology.

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  1. Cardiovascular physiology. Dr James Ker

  2. 2 scenario`s in cardiology: • Systemic diseases affecting the cardiovascular system. • Primary cardiovascular diseases.

  3. How can these diseases affect the cadiovascular system ? Components of the cardiovascular system: • Myocardium: myocarditis, cardiac failure etc • Valves: Stenosis, incompetence etc • Electrical system: Dysrhythmias. • Vessels: Arteries, veins, lymphatic vessels.

  4. Physiological disturbances: • Disturbances in the following may occur: • Blood pressure • Cardiac rhythm • Valvular function • Cardiac systole and diastole • Blood flow

  5. Blood pressure: • BP = Cardiac output (CO) x peripheral vascular resistance (PVR) • 3 components of blood pressure: • Systolic component • Diastolic component • Mean arterial pressure

  6. BP = 120/80 mmHg • Mean arterial pressure = (S + 2D)/3 or • D + 1/3 PP • Pulse pressure=S – D (120-80=40 mmHg)

  7. Cardiac output: • CO = Stroke volume x heart rate • Thus: 2 ways to increase CO: SV vs CO Determines systolic BP Systolic vs diastolic HT Normal CO: 5L/min Cardiac index=CO corrected for body surface area

  8. Causes of increased CO: • Fever • Anaemia • Hyperthyroidism • Pregnancy • Exercise • Etc..

  9. Presents as: • Systolic HT with: • ↑ pulse pressure • Stroke volume: Volume of blood pumped by ventricle during systole (70 ml at rest)

  10. Physiological control of CO: • Preload: Venous filling • Afterload: BP against which LV must expel stroke volume • Inotropy: Strength of myocardial contraction. Starling`s law, catecholamines

  11. Physiological control of heart rate: • Intrinsic: SA node • Extrinsic: Hormonal: thyroid, catecholamines Neurological: Autonomic nervous system Fever, electrolytes

  12. Peripheral vascular resistance: • Determined by diameter of peripheral arteries. • Determines diastolic blood pressure

  13. Control of PVR: • Hormonal: AT II, endothelins, NO, bradykinin, catecholamine etc • Neurological: Autonomic nervous system • Myogenic/Local.

  14. The ECG: • Einthoven`s trangle • Einthoven`s law

  15. Einthoven`s triangle: I + - - - III II + +

  16. Einthoven`s law: • Lead II = Lead I + Lead III • Standard limb leads: I, II, III • Lead I: connects 2 arms • Lead II: connects right arm with left leg • Lead III: connects left arm with left leg

  17. aV leads: • Limb leads are bipolar • Unipolar limb leads=aV leads: aVR, aVL and aVF

  18. Precordial (V) leads: • V1: Just to the right of the sternum in the 4`th intercostal space. • V2: Just to the left of the sternum in the 4`th intercostal space. • V3: Halfway between V2 and V4

  19. V4: Left midclavicular line in the 5`th intercostal space • V5, 6: 5`th intercostal space in anterior and midaxillary line respectively

  20. Physiological use of the ECG: • Rhythm: Sinus vs other • Chamber thickening: Atrial and ventricular hypertrophy • Damage: Endocardial, myocardial, pericardial • Info on systemic conditions: Hypothermia, electrolyte disturbances, pH disturbances

  21. Rate, complexes, intervals: • P-wave: Atrial depolarization • QRS-complex: Ventricular depolarization • T-wave: Ventricular repolariation

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