Question

How does hypertension lead to left-sided heart failure, include the RAAS system? (pathophysiology) at a basic cellular level.

Answer 1

* Hypertension leads to left heart failure through,

                   * Elevation of blood pressure result in increase pheripheral resistance of major

                     and minor arteries especially coronary arteries and aorta.

                  * Increased pheripheral resistance result in increase in workload of heart and myocardial

                     muscles work hard for overcome the resistance and maintain normal cardicac output.

                  * Overactivity of cardiac muscles especially in the left ventricle to overcome high resistance

                     of aorta result in left ventricular hypertrophy.

                *Along with left ventricular hypertrophy(LVH) myocardial infarction occurs due to hypertension

                  affect the walls of coronary arteries result in plaque accumulation and atherosclerosis.

               * Both LVH and MI result in left ventricular dysfunction .

                * Left ventricular dysfunction leads to left-sided heart failure.

* RAAS

(Renin angiotensin-aldosterone system).

      * It is a system used by the body to regulate blood pressure and fluid volume.

      * Mechanisms in RAAS are

                         * It begin with liver,the liver produces a pre-enzyme called angiotensinogen it convert

                            into angiotensin 1 by renin released from the kidney.

                         * The kidney releases renin due to low fluid volume in the nephrons.

                         * The angiotensin 1 then converted to angiotensin 2 with the help of ACE

                             (Angiotensin converting enzyme) release from lungs.

                          * Angiotensin 2 act on adrenal glands to release aldosterone.

                          * Aldosterone release from adrenal gland which is a steroid hormone act on the

                              collective duct of nephrons of the kidney and causes retain water.

                            * Water retention result in elevation of blood pressure.