The P wave is gone, what is the corresponding disease? Expert interpretation is coming

time:2022-12-09 11:05:52source:monlittlebaby.com author:Baby care
The P wave is gone, what is the corresponding disease? Expert interpretation is coming

*For medical professionals to read and refer to the class notes - "Dr. Liu Xingpeng ECG Time 2.0: Theory" Lecturer: Liu Xingpeng Beijing Chaoyang Hospital Affiliated to Capital Medical University ECG is an important tool for cardiologists to judge diseases, but many doctors do not understand ECG thoroughly. The reason is that in the daily diagnosis and treatment process, we only look down at the doctor and do not summarize the knowledge learned from the cases. But it doesn't matter, Xiaojie has organized and summarized the relevant courses of ECG, from principles to analysis ideas, and guides you to understand ECG. Today, let's start with the P wave, and see what disease it corresponds to if the first P wave that appears in an ECG cycle is gone. Xiaojie has carefully prepared knowledge notes for everyone. You can use them according to the course. Two formulas summarize the characteristics of P wave disappearance. The P wave reflects the atrial excitation mediated by the sinoatrial node. If there is no P wave, it means that the excitation is likely to be abnormal at this time. . So what happened to the disappearance of the P wave? Generally speaking, there are two situations. In order to facilitate memory, it can be summed up in the following two poems: The first one we call it "the flowers fall out of nowhere", in this case, the P wave disappears completely, really disappeared. In another case, we call it "invisible in the flowers". At this time, the P wave is just hidden, and it may be hidden in the QRS wave or the P wave. Let's first take a look at what happens when the P wave really disappears: 1. The sinoatrial node is really not working, and there is no ectopic excitement, then the P wave is completely gone. 2. The sinoatrial node is working, but a "sinoatrial block" occurs during the conduction of the sinoatrial node to the atrium, and the signal cannot be transmitted. 3. The sinus node is working, and the conduction can be passed down at the same time, and there is no sinoatrial block. However, the atrial muscle was severely abnormal, so the P waves were invisible. Reason for the disappearance of the first P wave: Sinus arrest The most common cause of inactivity of the sinus node is sinus arrest, as shown in the ECG (Figure 1), we can see some ectopic rhythms, the QRS complex is compared Wide, showing left bundle branch block morphology. When looking for a P wave in the R-R interval, no P wave can be seen at any location except the circled place where it may be a P wave. This shows that the patient is indeed in a state of sinus arrest at this time, and the sinus node is not working at all. Such ECG findings are common in patients with sick sinus syndrome. Figure 1. Annotation with suspicious P waves. The second reason for the disappearance of P waves: sinoatrial block. Next, let's look at the second type, sinoatrial block. At this point, it can be divided into two types: the first type is second-degree type I sinoatrial block, which is the Vennian phenomenon. In this case, the PP interval is gradually shortened, manifested by a gradual increase in heart rate, until a long interval occurs, no P waves appear, and the long PP time is <2 times the PP interval before the interval. Take the following figure as an example, the 2x interval is 740ms + 700ms = 1440ms, while the long interval is 1300ms, and 1300ms < 1440ms. Figure 2 The second type of Vennian phenomenon is second-degree type II sinoatrial block. In this case, the PP interval is constant until a long interval occurs, long PP time = 2 times the PP interval before the interval. Take the following figure as an example, 720ms+720ms=1440ms. Figure 3 Second-degree type II sinoatrial block When it comes to sinoatrial block, we should note that among the three types of sinoatrial block, first-degree sinoatrial block has no abnormal performance on ECG, and third-degree sinus block has no abnormal performance on ECG. Atrial block and sinus arrest are difficult to distinguish, only second-degree sinoatrial block can be reflected on the ECG. The reason is that we have no way to directly see the ECG curve of the sinoatrial node on the ECG. Techniques for judging P' waves In the figure below, we can see that the part marked by the red arrow behind the QRS complex in lead V1 has abnormal overlapping waveforms, but we cannot determine its nature, whether it is a P' wave or incomplete right ventricular conduction Blocked r' waves. In this case, look back at lead V5. If an r' wave is believed to appear in lead V1, an S wave will appear in lead V5, and no S wave is seen, indicating that it is a P' wave rather than an r' wave at this time. Figure 6 P' wave judgment P' wave can be seen after each QRS complex of AVNRT, and P' wave in leads V1-V2 may be mistaken for r' wave. Let's look at the case of AVRT. During AVRT, if the P' wave overlaps the T wave, it will become a sharp angle. The front branch of the T wave is slow and the back branch is steep. If the T wave has a sharp angle as shown in the figure below, it means that the T wave is fused with a P' wave. Figure 7. This little trick of the angular T wave small bound can help us quickly find the hidden P' wave in the T wave. To sum up: the hidden P' wave may have the following four situations: Mr. Liu's exclusive ECG reading experience, waiting for you to learn ~ the pediatric clinical knowledge doctor station app you want to see 👇 1. 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