Does nitroglycerin decrease preload or afterload?

Nitroglycerin reduces left ventricular afterload through arterial dilation as well as preload through venous dilation. This effect on afterload is not apparent from measurement of pressure in the brachial artery.

How does nitroglycerin affect cardiac output?

NTG induced sustained reductions in LV dimensions and transient increases in heart rate and dP/dt, and decreases in mean arterial pressure. Initially NTG increased cardiac output and flows to the coronary, mesenteric, renal, and iliac beds, while systemic and regional vascular resistances fell.

What is a physiologic effect of nitroglycerin reduces preload?

The Effects of Nitroglycerin: Nitroglycerin, a nitrate, causes smooth muscle relaxation. This produces systemic venous pooling of blood through the action of vasodilation. This, in turn, decreases venous blood flow return to the heart and reduces preload as well as venous afterload.

How do nitrates reduce preload?

Nitrates reduce the preload and the workload on the heart by increasing the venous capacitance and peripheral pooling of blood. This in turn reduces the myocardial oxygen demand [1].

Does Nitro increase or decrease afterload?

The effect of nitroglycerin (NTG) is mainly a reduction in preload and afterload. The decrease in afterload may be caused by a fall of total systemic resistance (TSR) or by an increase of arterial compliance (AC).

How does nitroglycerin cause vasodilation?

Nitroglycerin is denitrated by mALDH in smooth muscle and other cells. This results in the release of nitrite ion, which is then converted to nitric oxide. Nitric oxide that is released stimulates guanylyl cyclase in smooth muscle, producing an increase in cGMP which causes vasodilation.

Does digoxin decrease preload?

2. Digoxin in increasing doses slowed the heart rate at rest; with the daily dose of 0.50 mg from 63 +/- 10 to 53 +/- 6 beats min-1, and fractional shortening rose from 28 +/- 6 to 33 +/- 3% (P less than 0.05 for both). Preload, afterload and cardiac output did not change.

Does nitroglycerin decrease cardiac output?

Overdose toxicity from nitroglycerin is mainly a consequence of increased vasodilatory response. Hypotension, venous pooling, increased vasodilation, and reduced cardiac output can be expected in these patients. Compensatory effects, such as tachycardia and palpitations, can also be expected.

How do beta blockers affect preload and afterload?

Beta-blockers inhibit the sympathomimetic nervous system and block alpha1-adrenergic vasoconstrictor activity. These agents have moderate afterload reduction properties and cause slight preload reduction.

Does nitroglycerin cause vasoconstriction?

Background: Nitroglycerin therapy is associated with specific biochemical changes in the vasculature that may lead to increased vascular sensitivity to vasoconstrictors.

How does nitroglycerin promote vasodilation?

The body breaks nitroglycerin down into nitric oxide. Nitric oxide causes the smooth muscle within the blood vessels to relax. This allows the arteries and veins to open up, allowing more blood to flow through. Healthcare professionals call this action vasodilation.

What is preload and afterload?

Preload is the initial stretching of the cardiac myocytes (muscle cells) prior to contraction. It is related to ventricular filling. Afterload is the force or load against which the heart has to contract to eject the blood.