What is LMCA occlusion?
According to the literature total occlusion of the left main coronary artery usually causes a large infarction of the anterior wall leading to cardiogenic shock or sudden cardiac death.
What does ST elevation in aVL mean?
ST elevation in aVL and V2 through V5 signifies left anterior descending artery occlusion proximal to the first diagonal branch (positive predictive value [PPV] and negative predictive value [NPV] of 95% and 94%, respectively).
What does an ST segment elevation abnormality indicate?
The ST Segment represents the interval between ventricular depolarization and repolarization. The most important cause of ST segment abnormality (elevation or depression) is myocardial ischaemia or infarction.
What does ST elevation in anterior leads mean?
ST segment elevation in the anterior leads (V3 and V4) at the J point and sometimes in the septal or lateral leads, depending on the extent of the MI. This ST segment elevation is concave downward and frequently overwhelms the T wave.
What causes ST elevation in aVR?
Cause of ST elevation (STE) in AVR Two possible mechanisms: Diffuse subendocardial ischaemia, with ST depression in the lateral leads producing reciprocal change in aVR (most common) Infarction of the basal septum, i.e. a STEMI involving aVR.
Which artery is showing occlusion when leads I and AVL have ST segment elevation?
ST elevation in I and aVL signifies: Occlusion of a short LAD coronary artery before the first diagonal branch (if there is ST elevation in V2–V4).
What is AVf aVR AVL in ECG?
aVR means augmented Vector Right; the positive electrode is on the right shoulder. aVL means augmented Vector Left; the positive electrode is on the left shoulder. aVF means augmented Vector Foot; the positive electrode is on the foot.
Why does ST elevation happen?
ST segment elevation occurs because when the ventricle is at rest and therefore repolarized, the depolarized ischemic region generates electrical currents that are traveling away from the recording electrode; therefore, the baseline voltage prior to the QRS complex is depressed (red line before R wave).
What does the ST segment indicate?
ST segment represents the interval between depolarization and repolarization of the ventricles. It can be evaluated by using as baseline reference both the PQ and the TP segments, which are both expression of the diastolic potentials.
What causes ST elevation on ECG?
What does aVR show on ECG?
Thus, lead aVR is the augmented unipolar right arm lead and may be considered as looking into the cavity of the heart from the right shoulder. It follows that all normally upright deflections on the ECG will, under normal circumstances, be negative in this lead (10).
Is aVR ST elevation a STEMI?
ST elevation in aVR can also be seen in the context of anterior STEMI due to LAD occlusion proximal to the first septal branch, causing infarction of the basal septum.
Which coronary artery is most likely occluded in a patient with ST elevations in I aVL V5 and V6?
ECG Findings Inferolateral STEMI presents with ST-elevation involving lateral (I, aVL, V5, V6) and inferior leads (II, III, aVF): This is usually seen with occlusion of the proximal LCx artery.
What artery is likely occluded when ST elevation is noted in V1 and V2?
These findings, which include predominant ST-segment–elevation in V1-V2, initially suggested ischemia in the left anterior descending artery area, proximal to the first septal and the first diagonal branches.
What might an elevated ST segment of an ECG mean?
2 In non-pathological conditions, the elevation can reach even 0.3 mV in V2–V3, while is rarely more than 0.1 mV in the other precordial leads. In the MI, ST segment elevation is believed to represent a “current of injury” from damaged cells that are partially depolarized to the healthy myocardium.
What type of leads are aVR AVL and aVF?
These nine wires are known as “unipolar leads”. The three active peripheral leads are AVr, AVL, and AVf. These 3 leads create a triangle with the heart in the middle, as below.
Is ST elevation injury or ischemia?
A zone of ischemia typically produces ST segment depression. A zone of injury produces ST segment elevation.
What causes ST elevation in STEMI?
Pathologic ST Segment Elevation STEMI: Most commonly caused by an acute occlusion of a coronary blood vessel secondary to acute plaque rupture and thrombosis. However, cocaine use can also cause a STEMI due to coronary vasospasm, rather than occlusion with thrombosis.
What is the pathophysiology of ST elevation?
What causes AVR to be elevated in a LMCA?
Isolated elevation AVR is poorly specific for a LMCA. The following are other causes of aVR elevation: Nontraumatic thoracic aortic dissection. Massive Pulmonary Embolism. Massive GI bleed. Left bundle branch block (LBBB) Left Ventricular Hypertrophy (LVH) with Strain Pattern. Severe atrial tachydysrhythmias.
What is the mechanism of ST elevation in AVR?
Mechanism of ST elevation (STE) in aVR Lead aVR is electrically opposite to the left-sided leads I, II, aVL and V4-6. In the case of subendocardial ischaemia, ST elevation in aVR is simply a reciprocal change to ST depression in these leads
Why does subendocardial ischaemia result in ST elevation in AVR?
In the case of subendocardial ischaemia, ST elevation in aVR is simply a reciprocal change to ST depression in these leads ST depression does not localise, and thus subendocardial ischaemia due to oxygen supply/demand mismatch produces a consistent ECG pattern of lateral ST depression and reciprocal ST elevation in aVR
How is severe LMCA stenosis/3vd diagnosed in AVR?
Degree of STE in aVR was the strongest independent predictor of severe LMCA stenosis / 3VD requiring CABG (odds ratio 29.1), followed by positive troponin T level (odds ratio 1.27). STE ≥ 1.0 mm in aVR identified severe LMCA stenosis /3VD with 80% sensitivity, 93% specificity, 56% PPV, and 98% NPV.