正常成人左后胸导联心电图

目的 了解成人左后胸导联心电图正常值。方法 分析100例正常成人常规12导联及V7-9导联心电图。结果 V7、8导联q波时间均＜40ms，V9导联q波时间≥40ms者5例(5．2％)。V7—9导联ST段大多抬高＜0.5mm，但J点后80ms处ST段抬高＞1．0mm者分别为11％、8％及2％。结论 V7—9导联q波时间≥40ms、J点后80ms处ST段抬高＞1.0mm可诊断心电图异常。     

Right chest electrocardiographic patterns in normal subjects

Right-sided chest lead ECGs (V3R to V6R) were recorded in 110 normal male subjects who were between the ages of 17 and 22 years old (mean, 17.9 years). The prevalence of the rS pattern decreased from V3R (89 percent) to V6R (37 percent). However, the opposite was the case for the rSr pattern (10 percent in V3R and 36 percent in V6R). The amplitudes of the r wave, S wave and secondary r wave all progressively decreased from V3R to V6R. The prevalence of the qr and qS patterns was 0 and 1 percent, respectively in V3R and 14 and 2 percent, respectively in V6R. A positive ST segment deviation of 0.5 to 1 mm was present in 13 percent of subjects in V3R and 5 percent in V4R. T wave inversion was common and the prevalence increased from V3R (60 percent) to V6R (79 percent).     

Absence of ST elevation in ECG leads V7, V8, V9 in ischaemia of non-occlusive aetiologies

BACKGROUND AND OBJECTIVE: Occlusion of the circumflex coronary artery may present with either ST elevation typical of inferior or lateral myocardial infarction, ST depression or a normal 12-lead electrocardiogram (ECG). In patients presenting with ST depression, concomitant ST elevation in the posterior leads V7, V8 and V9 is believed to reflect ST-elevation myocardial infarction of the posterior wall. However, to be confident of this diagnosis, it is necessary to know that posterior ST depression does not occur in acute subendocardial ischaemia. METHODS AND RESULTS: We have prospectively recorded leads V7, V8 and V9 simultaneously with the standard 12-lead ECG in patients who underwent treadmill stress test. Group A consists of 35 patients who showed ischaemic praecordial ST depression in their 12-lead ECGs during treadmill stress test and subsequent angiographic documentation of significant coronary artery disease. Group B consists of 35 subjects who showed normal ECG findings during treadmill stress test. In none of the Group A or B patients was there ST elevation in leads V7, V8 or V9 either at rest or at peak exercise. ST depression was seen in 69% in V7, 31% in V8 and 11% in V9 in the Group A patients at peak exercise. CONCLUSION: ST elevation in leads V7, V8 and V9 is uncommon in patients presenting with subendocardial ischaemia. Therefore, in patients presenting with acute chest pain and ST depression in the 12-lead ECG, concomitant posterior ST elevation may be a reliable indicator of ST elevation posterior MI. This is likely due to circumflex artery occlusion and may require thrombolytic therapy.     

Acute myocardial infarction with isolated ST-segment elevation in posterior chest leads V7-9: "hidden" ST-segment elevations revealing acute posterior infarction.

OBJECTIVES: This study was done to determine whether electrocardiographic (ECG) isolated ST-segment elevation (ST) in posterior chest leads can establish the diagnosis of acute posterior infarction in patients with ischemic chest pain and to describe the clinical and echocardiographic characteristics of these patients. BACKGROUND: The absence of ST on the standard 12-lead ECG in many patients with acute posterior infarction hampers the early diagnosis of these infarcts and thus may result in inadequate triage and treatment. Although 4% of all acute myocardial infarction (AMI) patients reveal the presence of isolated ST in posterior chest leads, the significance of this finding has not yet been determined. METHODS: We studied 33 consecutive patients with ischemic chest pain suggestive of AMI without ST in the standard ECG who had isolated ST in posterior chest leads V7 through V9. All patients had echocardiographic imaging within 48 h of admission, and 20 patients underwent coronary angiography. RESULTS: Acute myocardial infarction was confirmed enzymatically in all patients and on discharge ECG pathologic Q-waves appeared in leads V7 through V9 in 75% of the patients. On echocardiography, posterior wall-motion abnormality was visible in 97% of the patients, and 69% had evidence of mitral regurgitation (MR), which was moderate or severe in one-third of the patients. Four patients (12%), all with significant MR, had heart failure, and one died from free-wall rupture. The circumflex coronary artery was the infarct related artery in all catheterized patients. CONCLUSIONS: Isolated ST in leads V7 through V9 identify patients with acute posterior wall myocardial infarction. Early identification of those patients is important for adequate triage and treatment of patients with ischemic chest pain without ST on standard 12-lead ECG.     

Electrocardiographic diagnosis of remote posterior wall myocardial infarction using unipolar posterior lead V9

The accuracy of four electrocardiographic criteria for diagnosing remote posterior myocardial infarction was assessed prospectively in 369 patients undergoing exercise treadmill testing with thallium scintigraphy. Criteria included the following: 1) R-wave width greater than or equal to 0.04 s and R-wave greater than or equal to S-wave in V1; 2) R-wave greater than or equal to S-wave in V2; 3) T-wave voltage in V2 minus V6 greater than or equal to 0.38 mV (T-wave index); 4) Q-wave greater than or equal to 0.04 s in left paraspinal lead V9. Twenty-seven patients (7.3 percent) met thallium criteria for posterior myocardial infarction, defined as a persistent perfusion defect in the posterobase of the left ventricle. Sensitivities for the four criteria ranged from 4 to 56 percent, and specificities ranged from 64 to 99 percent. Posterior paraspinal lead V9 provided the best overall predictive accuracy (94 percent), positive predictive value (58 percent), and ability to differentiate patients with and without posterior myocardial infarction of any single criterion (p less than .0001). Combining the T-wave index with lead V9 further enhanced the diagnostic yield: the sensitivity for detecting posterior infarction by at least one of these criteria was 78 percent, and when both criteria were positive, specificity was 98.5 percent. It is concluded that a single, unipolar posterior lead in the V9 position is superior to standard 12-lead electrocardiographic criteria in diagnosing remote posterior myocardial infarction, and that combining V9 with the T-wave index maximizes the diagnostic yield.     

Prognostic significance of right ventricular infarction diagnosed by ST elevation in right chest leads V3R to V7R

The prognostic significance of electrocardiographic "extensive right ventricular infarction" diagnosed by ST elevation greater than or equal to 1 mm in right chest leads V3R to V7R during inferior/posterior infarction was evaluated in 158 consecutive patients with first anterior (n = 72) or inferior/posterior (n = 86) myocardial infarction. At follow-up the maximum observation time was 3.0 years (mean 1.8 years). A total of 49 patients died; 96% due to cardiac causes. Twelve patients (8%) died during the first 24 hours of admission. Ten-day mortality was 18% (n = 29). Using Cox multivariate analysis ST elevation in right chest leads during inferior/posterior infarction was an independent predictor of prognosis in patients surviving the initial 10 days after infarction (n = 129). For these patients the cumulative survival was better after inferior/posterior infarction with ST elevation in V3R to V7R (n = 25) compared with (1) inferior/posterior infarction without St elevation in these leads (n = 45, P = 0.09), (2) anterior infarction (n = 59, P = 0.08), and (3) all other infarctions (n = 104, P = 0.05). Infarct size estimated by the peak serum enzyme values was similar in these groups. Thus, electrocardiographic extensive right ventricular infarction predicts a good prognosis in patients alive 10 days after infarction. Compared with infarcts of similar size but with another location the prognosis is better, probably due to concomitant smaller left ventricular infarction with better left ventricular function following infarction.     

70岁以上健康老年人右胸及后壁导联心电图特点分析

目的研究70岁以上健康老年人右胸及后壁导联心电图特点。方法对212例70岁以上健康老年人右胸及后壁导联的P波、QRS波及ST段进行形态观察及测量分析。结果(1)右胸导联rS波形检出率为31.1%～58.1%;QS波形检出率为14.0%～23.3%;V4R导联(QS波除外)、V5R导联各波振幅低于V3R导联(P<0.05);(2)后壁V7～V9导联qR波形检出率为50.0%～87.7%;R波形检出率为7.1%～34.9%;与V7导联比较,V8、V9导联qR波形的出现率递增,R波形出现率及R波振幅均呈现递减(P<0.05);(3)ST段:V3R～V5R导联97.5%～98.9%位于等电位线;V7～V9导联97.2%～98.5%位于等电位线;极少数抬高者幅度<0.05mV,无ST段下降;(4)T波:V3R～V5R导联61.3%～79.2%为平坦,21.8%～25.8%为倒置;V7～V9导联45.1%～78.5%为平坦,20.0%～53.7%为直立。结论建立70岁以上老年人右胸及后壁导联心电图的诊断标准具有实际的临床意义。     

Electrocardiographic alterations in leads V1 to V3 in the diagnosis of right and left ventricular infarction

As Q wave and ST segment elevation in leads V1 to V3 may be due either to right ventricular infarction (RVI) or to anterior left ventricular infarction (ALVI), 72 autopsy patients with acute myocardial infarction who had had conventional 12-lead ECG records were studied to determine the accuracy of these ECG criteria, both for the diagnosis of RVI (29 patients, group A) and of ALVI (43 patients, group B). The accuracy of three ECG criteria (Q wave, ST segment elevation greater than or equal to 0.05 mV, and ST segment elevation greater than or equal to 0.1 mV) in diagnosing group A and group B patients was determined in each precordial lead (V1, V2, and V3) and the three criteria were found to be significantly more accurate in diagnosing group B than group A patients. In conclusion, although Q wave and ST segment elevation in leads V1, V2, and V3 may be present in some cases of RVI, their accuracy is too low to be considered useful diagnostic criteria in these patients.     

Magnetocardiograms and their variation over the chest in normal subjects

Magnetocardiograms of 6 normal male subjects are presented. For each subject magnetocardiograms were taken at about 32 positions on the chest; the positions were the junctions of a 2 by 2 inch grid. The electrocardiograms of each subject are also presented, for comparison. The magnetocardiograms are recordings of that component of the magnetic field vector which is normal to the chest. They were taken in a magnetically shielded chamber with a newly developed superconducting magnetometer, and are as clear as the conventional electrocardiogram. They contain the same general features as the electrocardiogram such as QRS, T, P and U waves, but with different ratios. New information about the heart, unavailable to the electrocardiogram, is believed to be contained in the variation of the magnetocardiogram across the chest. It is not yet known how to extract this information.     

Electrocardiographic findings in acute right ventricular infarction: sensitivity and specificity of electrocardiographic alterations in right precordial leads V4R, V3R, V1, V2, and V3

To determine the sensitivity, specificity, predictive value and diagnostic efficiency of electrocardiographic alterations in the diagnosis of acute right ventricular infarction, 43 autopsy patients with acute myocardial infarction and an electrocardiogram including 12 leads plus leads V3R and V4R were studied. Group A included 21 patients with right ventricular infarction, of whom 14 (group AI) had posterior and 7 (group AII) had anterior right ventricular infarction. Group B included 22 patients without right ventricular infarction. Excluding group AII patients, the sensitivity of the presence of a Q wave reached 78.6% in lead V4R and decreased in leads V1 to V3; its specificity was low in all the leads. The sensitivity of ST segment elevation reached 100% in lead V4R and decreased in leads V1 to V3; its specificity was highest (68.2%) in leads V4R and V3R, its negative predictive value was 100% and its diagnostic efficiency was 80.6%. The criterion of ST segment elevation in lead V4R being higher than that in leads V1 to V3 was less sensitive (78.6%) than ST segment elevation in lead V4R alone, but its specificity reached 100%, its positive predictive value 100% and its diagnostic efficiency 91.7%. In conclusion, there are no electrocardiographic criteria to identify anterior right ventricular necrosis, but posterior right ventricular necrosis may be identified by the presence of a Q wave or ST segment elevation in the right precordial leads, reaching the highest sensitivity and specificity in lead V4R. The criterion of ST segment elevation in lead V4R being higher than that in leads V1 to V3 offers the highest specificity and efficiency in the diagnosis.     

Importance of posterior chest leads in patients with suspected myocardial infarction, but nondiagnostic, routine 12-lead electrocardiogram

Criteria for reperfusion therapy in acute myocardial infarction require the presence of ST elevation in 2 contiguous leads. However, many patients with myocardial infarction do not show these changes on a routine 12-lead electrocardiogram and hence are denied reperfusion therapy. Posterior chest leads (V7 to V9) were recorded in 58 patients with clinically suspected myocardial infarction, but nondiagnostic routine electrocardiogram. ST elevation >0.1 mV or Q waves in > or =2 posterior chest leads were considered to be diagnostic of posterior myocardial infarction. Eighteen patients had these changes of posterior myocardial infarction. All 18 patients were confirmed to have myocardial infarction by creatine phosphokinase criteria or cardiac catheterization. Of the 17 patients who had cardiac catheterization, 16 had left circumflex as the culprit vessel. We conclude that posterior chest leads should be routinely recorded in patients with suspected myocardial infarction and nondiagnostic, routine electrocardiogram. This simple bedside technique may help proper treatment of some of these patients now classified as having unstable angina or non-Q-wave myocardial infarction.