What is Subendocardial myocardial infarction?

What is Subendocardial myocardial infarction?

A subendocardial infarct results in necrosis exclusively inolving the innermost aspect of the myocardium. Usually a subendocardial infarct is the result of a partially occluded epicardial coronary artery (i.e. NSTEMI).

Which of the following ECG changes is an indication of subendocardial ischemia?

Widespread ST depression (leads I, II, V5-6) indicates subendocardial ischaemia.

What ECG findings is suggestive of myocardial infarction?

One of the most significant findings of myocardial infarction is the presence of ST segment elevation. The ST segment is the part of the ECG tracing that starts at the end of the S wave and ends at the beginning of the T wave. The point where the end of the Q wave and the ST segment meet is called the J point.

What is the difference between transmural MI and subendocardial MI?

The transmural type usually consisted of yellowish-brown coagulation necrosis in the center of an infarcted focus and coagulative myocytolysis at the marginal zone. The subendocardial type was characterized by coagulative myocytolysis throughout the entire focus.

What causes subendocardial infarction?

Global subendocardial infarcts occur when there is lack of oxygenation despite circulation—for example, when there is a respiratory arrest followed by prolonged hypoxemia.

What are the 4 types of myocardial infarction?

ST segment elevation myocardial infarction (STEMI) non-ST segment elevation myocardial infarction (NSTEMI) coronary spasm, or unstable angina.

Why is ST depression in subendocardial infarction?

ST-segment depression in epicardial electrograms can be a “reciprocal” effect of remote myocardial ischemia (MI), and can also be due to local partial-thickness or “subendocardial” MI. Experimental studies have shown either ST elevation or depression in leads overlying a subendocardial ischemic region.

Why is Subendocardium more prone to ischemia?

Subendocardial vulnerability to ischemia has been previously attributed to several mechanisms, namely, the greater subendocardial systolic compression was proposed to induce one or more of the following: 1) increased subendocardial vessel resistance (5, 36), 2) systolic backflow from endocardial to epicardial vessels ( …

Can ECG detect myocardial infarction?

Together with patient history and clinical findings, the 12-lead ECG is still the most readily available and best method for the early diagnosis of acute myocardial infarction.

What is the most common type of myocardial infarction?

Type 2 MI is the most common type of MI encountered in clinical settings in which is there is demand-supply mismatch resulting in myocardial ischemia. This demand supply mismatch can be due to multiple reasons including but not limited to presence of a fixed stable coronary obstruction, tachycardia, hypoxia or stress.

What are 3 symptoms of a myocardial infarction?

The symptoms of MI include chest pain, which travels from left arm to neck, shortness of breath, sweating, nausea, vomiting, abnormal heart beating, anxiety, fatigue, weakness, stress, depression, and other factors.

What are 4 signs of myocardial infarction?

What are the symptoms of acute myocardial infarction?

• pressure or tightness in the chest.
• pain in the chest, back, jaw, and other areas of the upper body that lasts more than a few minutes or that goes away and comes back.
• shortness of breath.
• sweating.
• nausea.
• vomiting.
• anxiety.
• feeling like you’re going to faint.

What is the difference between ST elevation and ST depression?

The normal ST segment is flat and isoelectric. The transition from ST segment to T-wave is smooth, and not abrupt. ST segment deviation (elevation, depression) is measured as the height difference (in millimeters) between the J point and the baseline (the PR segment).

Where is the Subendocardium?

Description. The Purkinje fibers (Purkyne tissue or subendocardial branches) are located in the inner ventricular walls of the heart, just beneath the endocardium in a space called the subendocardium.

Where is the subendocardial layer?

The endocardium is composed of the endothelium and the subendothelial connective tissue layer. The subendocardium is found between the endocardium and myocardium and contains the impulse-conducting system.

What does V1 V2 V3 mean in ECG?

The areas represented on the ECG are summarized below: V1, V2 = RV. V3, V4 = septum. V5, V6 = L side of the heart. Lead I = L side of the heart.

What are the 5 types of myocardial infarction?

What is the best treatment for myocardial infarction?

Beta blockers, glyceryl trinitrate and possibly ACE inhibitors work in this way. All patients with a suspected myocardial infarction should be given aspirin. It is a powerful antiplatelet drug, with a rapid effect, which reduces mortality by 20%. Aspirin, 150-300 mg, should be swallowed as early as possible.

What causes Subendocardial injury?

We conclude that subendocardial infarction is symptomatically an unstable entity, is associated with severe coronary artery disease and, in a medically treated group, is followed by a significant incidence of early transmural myocardial infarction (21 per cent).

Why is ST depression in subendocardial ischemia?

ST segment depression occurs because when the ventricle is at rest and therefore repolarized, the depolarized ischemic subendocardium generates electrical currents that are recorded by an overlying electrode.

Why the Subendocardium is most vulnerable to ischemia?

In conclusion, subendocardial vulnerability to a acute reduction in perfusion pressure stems primarily from differences in vascular compliance induced by transmural differences in both extravascular loading and vessel wall thickness.

What are the 3 tissue types in the heart?

The wall of the heart separates into the following layers: epicardium, myocardium, and endocardium. These three layers of the heart are embryologically equivalent to the three layers of blood vessels: tunica adventitia, tunica media, and tunica intima, respectively.

Why is V1 and V2 negative in ECG?

Because the left ventricular mass is larger than that of the right ventricle, the vector corresponding to the ventricular mass depolarization is directed towards the left. Thus, the ventricular depolarization corresponds to a negative deflection (S wave) in V1 and V2 and a positive deflection (R wave) in V3 and V4.

What is the difference between myocardial injury and myocardial infarction?

Specifically, myocardial injury is defined by at least 1 cardiac troponin concentration above the 99th percentile upper reference limit. Myocardial infarction is a form of myocardial injury but requires clinical evidence of acute myocardial ischemia.

What is Subendocardial ischaemia?

Most forms of heart disease cause myocardial damage which often is confined to the deep (subendocardial) layer of left ventricular muscle. Much clinical and experimental evidence suggests that subendocardial muscle is prone to ischaemic damage, and a physiological mechanism for this vulnerability is described.