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The cardioaccelerator center also sends additional fibers, forming the cardiac nerves via sympathetic ganglia (the cervical ganglia plus superior thoracic ganglia T1–T4) to both the SA and AV nodes, plus additional fibers to the atria and ventricles. The ventricles are more richly innervated by sympathetic fibers than parasympathetic fibers.
T1 mapping has also been developed to quantify diffuse myocardial fibrosis. [20] T2-weighted imaging is mainly used to detect myocardial edema which may develop in acute myocarditis or infarction. Phase-contrast imaging uses bipolar gradients to encode velocity in a given direction and is used to assess valve disease and quantify shunts .
In this case a clot or thrombus can form, blocking the artery, and restricting blood flow to an area of heart muscle causing a myocardial infarction (a heart attack) or unstable angina. [57] In the worst case this may cause cardiac arrest , a sudden and utter loss of output from the heart. [ 58 ]
Cardiac muscle forms both the atria and the ventricles of the heart. Although this muscle tissue is very similar between cardiac chambers, some differences exist. The myocardium found in the ventricles is thick to allow forceful contractions, while the myocardium in the atria is much thinner.
Myocardial contractility represents the innate ability of the heart muscle (cardiac muscle or myocardium) to contract. It is the maximum attainable value for the ...
In patients with stable coronary artery disease, the troponin T concentration has long been found to be significantly associated with the incidence of cardiovascular death and heart failure, but it was 2014 before it began to be accepted as a predictor of who would later suffer acute myocardial infarction (heart attack). [10] [11]
Myocarditis has been reported to be a major cause of sudden cardiac death (SCD) in infants, adolescents, and young adults, but the reported rates show wide variation (1 to 14 percent) among young people depending on differences in SCD definition and classification/ definition of myocarditis post-mortem as well as heterogeneity of study populations.
Other ECG changes associate with myocardial ischaemia are: ST segment depression with an upright T wave; ST segment depression with biphasic T wave or inverted T wave with negative QRS complex; [5] T wave symmetrically inverted with a pointed apex, while the ST segment is either bowed upwards or horizontally depressed, or not deviated; and ST ...