Myocardial oxygen demand decreases by all EXCEPT
(Amrinone) (507-KDT 6th)Antianginal agents (organic nitrates, b. Blockers, CCBs) lowers the oxygen demand of the heart by affecting BP.Venous return. Heart rate and contractility (209-Lippncott's 4th)Drugs that reduce cardiac size, rate or force reduces cardiac oxygen demand. Thus vasodilators, b blockers and calcium blockers have predictable benefits in angina (192-Katzung 11th)Drug used in Angina Pectoris (i) Nitrates - nitroglycerin, Isosorbide dinitrate, Isosorbide mononitrate(ii) Beta blockers - Propranolol, Atenolol, metoprolol (iii) Calcium channel blockers - Verapamil, Diltiazem, Nifedipine(iv) Miscellaneous - Ranolazine, IvabradineDILTIAZEM - (CCBs) (530-KDT 6th)* Direct depression of SA node and AV conduction* Decrease HR.B.P* Vasodilator - can relieve coronary artery spasm* Modest negative inotropic actionMETOPROLOL - (Cardio selective, class II anti arrhythmic drugs p-adrenergic antagonist)* Act by decreasing cardiac work and O2 consumption (decreased HR, inotropic state and mean BP)* Depressing automaticity, contractility and prolonging AV conductionNITRATES (523- KDT6th) (210- Lippincott's 4th)* These compounds cause a rapid reduction in myocardial oxygen demand-followed by rapid relief of symptoms* Nitates decreases coronary vasoconstriction or spasm and increases perfusion of the myocardium by relaxing coronary arteries. In addition they relax veins, decreasing preload and myocardial oxygen consumption.AMRINONE (Inamrinone) - Phosphodiesterase III inhibits*** Positive inotropy and direct vasodilators * It increases cardiac index, left ventricular ejection fraction and decreases peripheral vascular resistance. CVP. Left ventricular and diastolic volume and pressureCardiac O2 demand or O2 consumptionCorrelates with ventricular work per beatSo O2 demand a ventricular work per beat a stroke volume x mean arterial pressure**Cardiac O2 demand is determined primarily br - Intramyocardial tension, wall thickness, ventricular radius (volume)- Contractile site of the myocardium - Heart rateO2 consumption is ~ 9ml/100g/min by beating heart of rest & increases with exercise & various other states
Diltiazem
Metoprolol
Nitroglycerine
Amrinone
C.V.S