Lactate accumulation reduces contractility and eventually necroses cardiomyocytes, releasing their troponin storage into the bloodstream. Serum troponin elevation is a characteristic biomarker of MI.Depending on the severity of ischemia, MIs are categorized as NSTEMI or STEMI. NSTEMI stands for Non-ST Elevation Myocardial Infarction, referencing the lack of ST-segment elevation in ECG traces. This is because in NSTEMI, only part of the myocardial wall is infarcted, which does not diagnostically present with ST-elevation. NSTEMI becomes STEMI when the entire myocardial wall is infarcted. Diagnostically, STEMI displays prolonged ST-segment elevation in ECG traces, and is thus named ST-Elevation Myocardial Infarction. Minutes after STEMI, fatal cardiac arrest could occur. STEMI is life-threatening if immediate reperfusion therapy is not initiated. Gangrene
Gangrene, specifically dry gangrene, is caused by an atherosclerotic or thromboembolic arterial occlusion. Gangrene is a complication of prolonged PAD, leading to shriveling, blackening, and infarction of peripheral tissue, commonly in the extremities. In severe cases, amputation of the affected limb is required. Ischemic Stroke
Ischemic stroke is a thrombotic, or rarely, thromboembolic or atherosclerotic complication of arteries supplying the brain. Occlusion of brain arteries leads to rapid ischemic death of neurons, both at the infarct core and ischemic penumbra. Similar to cardiomyocytes, neurons require constant perfusion for proper function. Any interruption of blood supply causes neurons to switch to anaerobic metabolism, exhausting intracellular ATP levels. ATP depletion causes an influx of calcium cations into neurons and efflux of excess glutamate, triggering the apoptosis and necroptosis of neurons.Neuronal necrosis precipitates irreversible brain damage.
Cerebral areas most susceptible to ischemic damage include the speech and motor cortices, leading to contralateral paralysis, speech, and comprehension loss. Severe or prolonged strokes may terminate in coma or brain death. Therefore, the diagnosis and treatment of ischemic stroke are time-dependent. Diagnosis
There are several methods of diagnosing arterial occlusion, ranging from straightforward setups like exercise testing, to advanced scanning equipment such as ultrasonic duplex scanning or Multi-Detector Coronary Tomography (MDCT) angiography. Exercise Testing
Exercise testing is a simplistic, non-invasive method of diagnosing intermittent claudication. Blood pressure measurements at the suspected area can be taken before and after exercise, as some symptoms only appear during strenuous activity. Commonly, a treadmill setting at 2 mph with a 12-degree slope is utilized. Subjects are asked to walk on the treadmill for a maximum of 5 minutes or until moderate pain is felt. The time to pain or maximal walking duration is recorded and compared with baselines. Healthy individuals maintain systolic blood pressures at a normal range. Once exercise becomes more intense, there may be a temporary fall in systolic pressure, which quickly returns to normal with rest. However, those with intermittent claudication struggle to maintain standard values of systolic pressure, while recovery back to baseline is prolonged. Ultrasonic Duplex Testing
Ultrasonic duplex scanning was developed to primarily determine the extent of atherosclerosis in carotid arteries. Since then, its application has widened to include arteries in the limbs. The technique utilizes high-frequency sound waves for visualization of flow direction and velocity within the arteries in an area of interest.