Injury patterns

Blast victims, though rarely treated in domestic U.S. hospitals, presentwith injury patterns that are unique to their mechanism. 

In acute phase, usually the ECG shows at the same time patterns of injury, ischaemia and even necrosis, and in chronic phase there are frequently Q waves and abnormal T waves. These different ECG patterns are not present exactly in the same leads, because although the areas of infarction, injury and ischaemia often coincide, they are not usually identical and especially the injury pattern (ST-segment deviations) in acute phase is present in more leads than is the necrosis pattern (Q wave or equivalent) in chronic phase. 

When acute coronary occlusion is carried out in experimental animals with closed thorax, it gives rise, during the initial phase of ischaemia, to a delay in repolarisation (TAP) in the subendocardium, which is the area that first suffers ischaemia (Lengyel et al, 1957). This subendocardial ischaemia is evidenced by a tall and peaked T wave immediately followed by ST-segment elevation (injury pattern) if the occlusion persists and the ischaemia becomes severe and transmural (see ECG pattern of injury p. 55). This pattern maybe self-limited if the occlusion is temporary, as in coronary spasm (Prinzmetal... 

Figure 3.9 In case that in basal state a certain degree of ischaemia with subendocardial predominance exists too mild to produce clear ECG changes, an increase of active ischaemia still with subendocardial predominance will produce an ST-segment depression (subendocardial injury pattern) (A). If as a consequence of ischaemia there is a delay in repolarisation predominating in subepicardium or being transmural, a flattened or negative T wave appears in leads with, but also without, predominant R wave (B-1) (subepicardial ischaemia pattern). The latter pattern is...

In human beings, the electrocardiographic injury pattern is seen in the presence of evident and persistent clinical ischaemia. When we extrapolate the findings in the experimental field to clinical practice, it could be considered that when the ischaemia is important, persistent and predominant in a certain area (subendocardium or subepi-cardium), an evident diastolic depolarisation in that area generates a low-quality TAP (slower... 

Both the clinical ST-segment depression pattern and the experimental subendocardial injury pattern have a common explanation the sum of subendocardium TAP, which is of worse quality than in the subepicardium (Figure 4.5), or the generation of an injury vector (Figure 4.8). In NSTE-ACS the presence of new ST-segment depression is related with the presence of evident active ischaemia predominantly in the subendocardium. On the other hand, the presence of flat or negative T wave is related with previous ischaemia (often is a reperfusion pattern) without subendocardial predominance (Table 2.1 and Figure 3.9). 

In cases of LVH with strain pattern and/or wide QRS complex, the electrocardiographic diagnosis of injury pattern is frequently more difficult, especially in the presence of an LBBB or pacemaker. However, in some ACS, especially those secondary to the total proximal occlusion of an epicardial coronary artery, ST-segment elevation are well seen in the presence of complete RBBB (Figure 4.66), and also in the course of ACS the presence of complete LBBB or pacemaker allows us to visualise usually very well the ST-segment elevation (Figures 4.67 and 4.68A). 

Figure 8.10 Patient with crises of Prinzmetal angina, who presented during these crises typical of subepicardial injury pattern. During the remission of pain (Holter method recording) the injury pattern disappeared within a few seconds.

On the contrary, in Q-wave infarction the coronary artery occlusion is usually complete, and classically it was considered that the MI was transmural and often presents homogeneous wall involvement (QS pattern) or at least the infarction involves the subendocardium and also part of the subepicardium in contact with the subendocardium (QR pattern) (Figure 5.2C). CMR has demonstrated that often Q-wave Mis are not trans-mural and, on the contrary, often are transmural non-Q-wave Mis (Moon et al., 2004). The Q-wave MI often appear in a patient without very much prior ischaemia (first infarction). Consequently, an acute ischaemia (ACS) generates a poor-quality TAP in the entire wall that is recorded, from the precordium, as subepicardial injury pattern (ST-segment elevation) (Figures 4.5 and 4.8). Later, the myocardium becomes non-excitable and Q wave of necrosis develops (Figures 5.2B and 5.3). 

Bayley RH, La Due JS. Electrocardiographic changes of impending infarction, and the ischemia-injury pattern produced in the dog by total and subtotal occlusion of a coronary artery. Am Heart J 1944 28 54a. 

Ptange, M., Heller, M., Watson, H., Iyer, M., Ivarsson, B. J., Fisher, J. (2010). Age effects on injury patterns in pedestrian crashes. SAE Intematiomd Journal of Passenger Cars— Mechanical Systems, 5(1), 789-820. 

AM and PL bundles. On the other hand, some authors noted that, even with extensive clinical and imaging assessment, the exact injury pattern of an isolated bundle tear might only be established arthroscopically [10, 11, 14, 17, 24]. Therefore, there is a possibility that comprehensive examinations including arthroscopic observation may find out some degrees of one-bundle injury without any abnormalities in the other bundle. However, the present study suggests that such knees may not clinically show any abnormal laxity. However, the authors believe that such knees without any instability are not involved in the indications of ACL reconstruction surgery. 

Avulsion fracture of the ACL occurs during sports activities and traffic accidents. Generally, it is seen more often in children than in adults, most likely because the ACL attachment site on the bone is immature and biomechanically weak in children [2]. Avulsion fracture of the ACL often occurs in children between ages 6 and 17 years [3-5]. Previous reports have suggested that the mechanism of injury is direct force, with hyperextension of the knee and injury patterns similar to ACL tears [6-9]. 

Anatomical and biomechanical factors account for the difference in injury patterns encountered between children and adults. This chapter will discuss the basic concepts of ultrasound, the normal appearance of the musculoskeletal tissues and the applications of ultrasound in paediatric musculoskeletal trauma. 

Musculoskeletal injuries in children fall into three main groups Accidental trauma such as road traffic accidents and falls, non-accidental injury (NAl) and sport related injury. For each of these groups specific injury patterns can be recognised that are unique to the growing skeleton. 

The force generated by muscle contraction is transmitted to bone by tendons, with the muscle-tendon-bone combination forming a functional unit which can be referred to as the musculoskeletal chain. There are important differences between the child, the young adult and the mature adult which account for the different injury patterns that are encountered (Harris 1981). In children, the weak links in the musculoskeletal chain are at the bone-tendon interface and at the growth plate, which accounts for the high occurrence of apophyseal avulsion injuries... 

This is the least severe type of injury pattern with internal rotation of the innominate bone which pivots on the anterior margin of the sacroiliac joint. There may be compression fractures of the sacrum. Pubic rami fractures are common and typically have a known oblique orientation but can be comminuted, compared with the vertical fractures of AP compression injuries (Figs. 12.10,12.11). 

In adults ankle fractures are traditionally classified according to the forces involved in producing the injury (Lauge-Hansen 1950). In children, the presence of the physis allows the same forces to produce different injury patterns. The Salter-Harris classification of physeal fractures is well recognised. Therefore, Dias and Tachdjian (1978) modified the Lauge-Hansen classification to include the Salter-Harris classification and describe physeal injuries of the ankle in children. In the original classification there were four types of injury, each with a two-part name ... 

The lower five cervical vertebrae are similar in development, morphology and injury patterns and differ from the upper two vertebrae. Lower C-spine injuries are more common in older children and adolescents and are usually due to sports or motor vehicle accidents. 

Fig. 1.9 Atrial and ventricular electrograms (EGM) as obtained through a Medtronic Pacing System Analyser Model 5311. Ventricular. Above A typical rS configuration with a minor current of injury pattern. Below The current of injury pattern is more pronounced. Atrial Above A typical rS pattern. Below Approximately 150ms after the atrial electrogram lies a large far-field ventricular electrogram.

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