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A coronary CT calcium scan is a computed tomography (CT) scan of the heart for the assessment of severity of coronary artery disease. Specifically, it looks for calcium deposits in atherosclerotic plaques in the coronary arteries that can narrow arteries and increase the risk of heart attack. [1] These plaques are the cause of most heart ...
These calcium ions bind to and open more calcium channels (called ryanodine receptors) located on the sarcoplasmic reticulum within the cell, allowing the flow of calcium out of the SR. These calcium ions are responsible for the contraction of the heart. Calcium also activates chloride channels called I to2, which allow Cl − to enter the cell ...
Positive Bowditch effect causes an increase in cardiac output due to the increased force of contraction of heart muscles. [7]This phenomenon is usually absent or even reversed (negative Bowditch effect) in heart failure and other diseases of heart, such as cardiomyopathy and coronary artery disease.
In Stone Heart Syndrome, this delicate balance is disrupted. The excessive influx or release of calcium from intracellular stores overwhelms the cell's ability to remove it, leading to a sustained contraction state. [1] This prolonged contraction causes the heart muscle to become extremely rigid, resembling stone - hence the syndrome's name.
Increase the amount of calcium in the sarcoplasm. More calcium available for Troponin to use will increase the force developed. Decreasing contractility is done primarily by decreasing the influx of calcium or maintaining lower calcium levels in the cytosol of cardiac myocytes during an action potential.
Contraction band necrosis is a type of uncontrolled cell death unique to cardiac myocytes and thought to arise in reperfusion from hypercontraction, which results in sarcolemmal rupture. [ 1 ] It is a characteristic histologic finding of a recent myocardial infarction (heart attack) that was partially reperfused.
It is important to note that intracellular calcium causes muscular contraction in contractile cells, and is the effector ion. In heart pacemaker cells, phase 0 depends on the activation of L-type calcium channels instead of the activation of voltage-gated fast sodium channels, which are responsible for initiating action potentials in ...
Once calcium is confirmed to be elevated, a detailed history taken from the subject, including review of medications, any vitamin supplementations, herbal preparations, and previous calcium values. Chronic elevation of calcium with absent or mild symptoms often points to primary hyperparathyroidism or Familial hypocalciuric hypercalcemia. For ...