THE Q WAVE IN L III AND aVF OF THE ELECTROCARDIOGRAM—A Vectorcardiographic Analysis With the Use of the Frank System

Seventy-three consecutive patients with a Q wave in Lead III and aVF in the electrocardiogram were studied. Vectorcardiograms were recorded with the use of the Frank system.In 32 cases the ECG''s were compatible with the diagnosis of an inferior myocardial infarction based on a Q wave in Lead III and/or aVF greater than 0.04 second duration and greater than 25 per cent of the amplitude of the R wave. In this group, there were 16 patients with coronary disease and the VCG confirmed the electrocardiographic diagnosis of an infarction in 14 cases. In 13 of the other 16 cases without history of coronary disease the VCG did not suggest the presence of an infarction.In all 17 cases with questionable electrocardiographic diagnosis of an inferior infarction, and without history of coronary disease, the VCG denied the presence of an infarction. In 18 cases with small Q III or Q aVF the VCG''s were within normal limits. In two cases with normal Q III and Q aVF the VCG''s did not detect the presence of an infarction in both cases.The vectorcardiographic diagnosis of an inferior myocardial infarction was based on the superior orientation (at or above 360 degrees) of the 10, 20, 25 and 30-msec vectors in the frontal plane, superior displacement of the maximum QRS vector and clockwise rotation. In the left sagittal plane the 10, 20, 25 and 30-msec vectors were oriented at or above 180 degrees with the loop rotating counterclockwise.The data presented suggest that vectorcardiography is a useful adjunct to electrocardiography in the diagnosis of an inferior myocardial infarction.     

Vectorcardiographic Evaluation of Postoperative Changes in Patients with Interatrial Septal Defect: A Review of 55 Cases

The pre- and post-operative vectorcardiograms of 55 patients with atrial septal defect (ASD) are discussed. Forty-nine were of ostium secundum type and six of ostium primum type. The criteria used to study the regression of right ventricular hypertrophy were: in the horizontal plane, the ratio of anterior-over-posterior forces, the right-over-left forces and the rotation of the body of the QRS loop; in the frontal plane, the direction of half-area vector. Using these criteria, 46 out of 49 patients with defects of the ostium secundum type had vectorcardiographic evidence of regression of right ventricular hypertrophy. Marked clinical improvement was also demonstrated in all these patients. The three patients in whom improvement was not demonstrated on the vectorcardiogram had persistence of a cardiac defect. Following surgery two children with ostium primum defects showed no change in the frontal plane, whereas in the horizontal plane a normalization of vectorial forces was observed.     

正常家鸽的宽频带心电图时域值和功率谱

实验用南京新博公司生产的NHE-1000型宽频带心电信息检测分析仪,研究了正常家鸽宽频带心电图(WFB-ECG)的时域值和QRS波群的功率谱。主要结果如下:(1)Ⅱ、Ⅲ、aVF导联,QRS波群均为主波向下,形成rS或 rSr’型,无Q波,与人类相应导联的心电图波形相反;S波的升支均有一较大的切迹(无一例外),Ⅱ导联切迹幅度为 0.413±0.133mV,宽度为9.733±1.291ms;Ⅱ、Ⅲ、aVF导联T波直立,方向均与主波相反门(1例除外)。aVR导联,QRS波群主波向上,形成Rs型,T波倒置,与主波方向相反(无一例外),也与人类aVR导联的波形相反。(2)P波时程与P-R段之比值为0.8,而人的为1.0-1.6,小鼠的为0.4。(3)Ⅱ导联QRS波群的功率谱特点:以低频信号(低于80 HZ)为主,而高频频段的相对能量比小鼠的低,比人的高,其中高频频段100-1000 Hz的相对能量为(10.181±7.443)％,80-300HZ为(15.418±10.579)％。(4)QRS波群的额面心电轴为-118°±10°(-96°～-136°);(5)心电向量环的位置与人类的相反,位于-90°～-180°相限。这些现象的产生原因可能是由于家鸽心室 Purkinje纤维末梢延伸到心外膜下心肌,导致心外膜下心肌先除极化,心内膜下心肌后除极化而产生的。     

The QRS Vectorcardiogram of the Normal Newborn Human

A four-electrode resistance-combined network system was used to record the vector-cardiograms of 15 full-term infants, from birth to 96 hours of life. In the horizontal plane the QRS loop was described in a clockwise manner anterior to the point of origin. Initially it was directed anteriorly to the left and, terminally, posteriorly to the right. In the sagittal plane the loop described a figure-of-eight, with minimal superior and inferior displacement of the anterior and posterior components. In the frontal plane the QRS vector loop was described in either a clockwise direction inferior to the point of origin or a clockwise direction superior to the point of origin. Alterations in the appearance of the QRS vectorcardiogram result from changes in spatial orientation.     

Diaphragmatic perfusion heterogeneity during exercise with inspiratory resistive breathing

Regional distribution of diaphragmatic blood flow (Q; 15-microns-diam radionuclide-labeled microspheres) was studied in normal (n = 7) and laryngeal hemiplegic (LH; n = 7) ponies to determine whether the added stress of inspiratory resistive breathing during maximal exercise may cause 1) redistribution of diaphragmatic Q and 2) crural diaphragmatic Q to exceed that in maximally exercising normal ponies. LH-induced augmentation of already high exertional work of breathing resulted in diminished locomotor exercise capacity so that maximal exercise in LH ponies occurred at 25 km/h compared with 32 km/h for normal ponies. The costal and crural regions received similar Q in both groups at rest. However, exercise-induced increments in perfusion were significantly greater in the costal region of the diaphragm. At 25 km/h, costal diaphragmatic perfusion was 154 and 143% of the crural diaphragmatic Q in normal and LH ponies. At 32 km/h, Q in costal diaphragm of normal ponies was 136% of that in the crural region. Costal and crural diaphragmatic Q in LH ponies exercised at 25 km/h exceeded that for normal ponies but was similar to the latter during exercise at 32 km/h. Perfusion pressure for the three conditions was also similar. It is concluded that diaphragmatic perfusion heterogeneity in exercising ponies was preserved during the added stress of inspiratory resistive breathing. It was also demonstrated that vascular resistance in the crural and costal regions of the diaphragm in maximally exercised LH ponies remained similar to that in maximally exercising normal ponies.     

Significance of fragmented QRS complexes for identifying culprit lesions in patients with non-STelevation myocardial infarction: a single-center, retrospective analysis of 183 cases

ABSTRACT: BACKGROUND: Fragmented QRS (fQRS) complexes are novel electrocardiographic signals, which reflect myocardial conduction delays in patients with coronary artery disease (CAD). The importance of fQRS complexes in identifying culprit vessels was evaluated in this retrospective study. METHODS: A 12-lead surface electrocardiogram was obtained in 183 patients who had non-ST-elevation myocardial infarction (NSTEMI) and subsequently underwent coronary angiography (CAG). On the basis of the frequency of fQRS complexes, indices such as sensitivity, specificity, positive and negative predictive values, and likelihood ratio were evaluated to determine the ability of fQRS complexes to identify the culprit vessels. RESULTS: Among the patients studied, elderly patients (age [greater than or equal to] 65 years) and those with diabetes had a significantly higher frequency of fQRS complexes (p = 0.005, p = 0.003, respectively). The fQRS complexes recorded in the 4 precordial leads had the highest specificity (81.8%) for indentifying the culprit vessel (left anterior descending artery). However, the specificity of fQRS complexes to identify lesions in the left circumflex and right coronary arteries was lower for the inferior and lateral leads than for the limb leads (65.5% versus 71.7%); however, the limb leads had higher sensitivity (92.3% versus 89.4%). And the total sensitivity and specificity of fQRS (77.1% and 71.5%) were higher than those values for ischemic T-waves. CONCLUSIONS: The frequency of fQRS complexes was higher in elderly and diabetic patients with NSTEMI. The frequency of fQRS complexes recorded in each of the ECG leads can be used to identify culprit vessels in patients with NSTEMI.     

心电图计分法定量评价糖尿病小型猪心肌梗死面积

目的探讨简便的Wagner心电图QRS评分结果与糖尿病小型猪急性心肌梗死面积的相关性。方法巴马小型猪12只,随机分为糖尿病组（n=6）和正常组（n=6）。一次性静脉注射STZ（150mg／kg）的方法建立小型猪糖尿病模型,分别在给药前、给药后1周、2周和3周,采集血液,监测血糖,空腹血糖持续增高（FBG≥7．0retool／L）者认为建模成功;其次,定位结扎糖尿病组和正常对照组小型猪冠脉左前降支第1和第2对角支之间部位,并在缺血10rain、30min、1h、48h后查心电图,行QRS心电图计分;然后利用心肌组织Evan’sblue和TTC染色计算梗死心肌体积;分析QRS心电图计分与心肌梗死体积的相关性。结果所有动物急性心肌缺血病理变化明显,48h后都有病理性Q波形成,糖尿病组QRS评分明显较对照组高（6．9±2．4VS．4．1±1．8,P〈0．05）;病理染色结果显示其梗死面积明显比对照组大（29．2±5．1％vs．15．3±3．4％,P〈0．05）,二者相关系数为0．92。结论糖尿病心肌急性缺血更容易导致心肌组织坏死,梗死面积明显比对照组大;心电图检测判断心梗面积与病理情况下心梗面积相关性良好。     

Temporal properties of high frequency intra-QRS signals in myocardial infarction and healthy hearts.

The prevalence of late potentials after myocardial infarction depends on the site of the infarction. This may be caused by the different activation onsets of the anterior and inferior myocardial segments. Therefore, in anterior infarcts the high frequency signals may be concealed within the QRS whereas in the inferior infarcts they last beyond the end of the QRS. We compared the timing and the spatial patterns of high frequency intra-QRS signals (IQSs) in the different infarction sites. We investigated 14 patients with anterior infarcts, 17 patients with inferior infarcts, and 10 healthy subjects. 31-lead magnetocardiograms were recorded in left precordial position and averaged. The QRS signals were smoothed with a Savitzky-Golay filter. The smoothed QRS signals were subtracted from the measured ones. The difference of the signals (frequency band of about 60-200 Hz) representing the high frequency components was quantified. The percentage of the high frequency signals was calculated for the entire QRS, for the first and for the second half, respectively. We found that in patients with anterior infarcts the high frequency components predominantly appeared in the first half of the QRS whereas in inferior infarcts these components predominantly appeared in the second half of the QRS. The different infarction sites were associated with different spatial patterns of the high frequency signals on the body surface. In healthy subjects there was not such a preferential association of time intervals and high frequency signals. Late potentials are the special case of high frequency signals appearing in the terminal QRS. It is the general property of the myocardium to generate high frequency signals associated with the depolarization of infarcted tissue. The timing of such signals and the spatial distribution patterns on the body surface may help to identify the location of the sources.     

NEGATIVE TREADMILL EXERCISE TEST RESULT WITH SUBSEQUENT MYOCARDIAL INFARCTION AND CORONARY ARTERY BYPASS: CASE REPORT

Myocardial infarction is a rare complication of maximal exercise testing.(1) In the case presented here, infarction occurred in a 54-year-old man, 14 minutes after he showed a normal response to maximal multistage treadmill exercise testing. The presence of coronary artery disease had been documented angiographically prior to exercise testing. After infarction, the patient underwent emergency double aortocoronary bypass to the left anterior descending and right coronary arteries with good results. Clinical evidence suggests that the extent of myocardial necrosis was reduced by timely surgical intervention. There is no conclusive explanation for this patient's normal response to maximal exercise testing in the presence of advanced coronary artery occlusive disease followed rapidly by infarction. The value of exercise testing is well established in assessing the existence or severity of coronary artery disease; a normal response, however, cannot be used as an infallible indication that critical coronary artery disease does not exist.     

Cervical magnetic stimulation: a new painless method for bilateral phrenic nerve stimulation in conscious humans

Assessing diaphragmatic contractility is a common goal in various situations. This assessment is mainly based on static or dynamic maximal voluntary maneuvers and twitch transdiaphragmatic pressures (Pdi) obtained by stimulation of the phrenic nerves (PS). PS eliminates the central components of diaphragmatic activation, but the available techniques of PS remain subject to some limitations. Transcutaneous PS is painful, and needle PS is potentially dangerous. Time-varying magnetic fields can stimulate nervous structures without pain and without adverse effects. In six subjects, we have studied cervical magnetic stimulation (CMS) as a method of PS. We have compared the stimulated Pdi (Pdistim) with the maximal Pdi obtained during static combined expulsive-Mueller maneuver (Pdimax) and with the Pdi generated during a sniff test (Pdisniff). CMS produced twitch Pdi averaging 33.4 +/- 9.7 cmH2O. Pdistim/Pdimax and Pdistim/Pdisniff were 24 +/- 6 and 41 +/- 14%, respectively. These values are comparable to those obtained in other studies with transcutaneous PS. They were highly reproducible in all the subjects. Electromyographic data provided evidence of bilateral maximal stimulation. CMS is a nonspecific method and may stimulate various nervous structures. However, diaphragmatic contraction was elicited by stimulation of the phrenic trunk, since the phrenicodiaphragmatic latencies (less than 7 ms) were in the range of values reported with direct stimulation of the trunk. Cocontraction of neck muscles, including the sternomastoid, was present, but its influence in the CMS-induced Pdi seems minimal. We conclude that magnetic stimulation is an easy, well-tolerated, reproducible safe, and valuable method to assess phrenic conduction and diaphragmatic twitch response.     

Spectral analysis of the EMG and diaphragmatic muscle fatigue during periodic breathing in infants

Periodic breathing occurs commonly in full-term and preterm infants. The mechanisms which switch breathing on and off within a cycle of periodic breathing are not certain. Since immature infants may experience diaphragmatic muscle fatigue, one potential switching mechanism is fatigue. Power spectra of the electromyogram, uncontaminated by the electrocardiograph artifact, were studied for evidence of diaphragmatic muscle fatigue during spontaneous periodic breathing in infants. A fall in the high-frequency (103-600 Hz) power and an increase in the low-frequency (23-47 Hz) power during periodic as compared with normal breathing would indicate fatigue. This effect was not observed in any of the infants studied. Hence, there is no evidence that periodic breathing is the result of diaphragmatic muscle fatigue. This finding suggests that the effect of drugs such as theophylline in eliminating periodic breathing may be unrelated to the fact that they also reduce fatigue.     

Statement of the ad hoc committee on the laboratory diagnosis of infectious and serum hepatitis.

A prospective study was carried out to determine the prognostic factors in patients with second-degree and complete heart block following acute myocardial infarction and to re-examine the indications for artificial transvenous pacing. Of the 117 consecutive patients with proved acute myocardial infarction, 15 developed advanced heart block (second degree and complete). The presence of the following factors, either alone or in combinations, were attended with poor prognosis: preceding Stokes-Adams syndrome, cardiogenic shock, congestive heart failure, complications secondary to cardiac arrest, anterior infarction and wide QRS complex. In the nine cases requiring artificial transvenous pacemaker because of Stokes-Adams attacks, congestive heart failure or frequent multifocal ventricular ectopic beats, there were five deaths. The remaining six patients, who were without complications and were not paced, all survived; these patients had normal QRS duration with heart rates above 60 per minute. This study indicates that prophylactic transvenous catheter insertion in acute heart block does not appear justified unless specific indication(s) arise. Postmortem studies revealed significant narrowing of all the major coronary vessels in all five fatalities. The overall mortality in this series of cases of acute heart block was 33%.     

Amelia: incidence and associated defects in a large population

Amelia, or complete absence of a limb, is a very rare congenital anomaly. The incidence of amelia in a population of 1,213,913 consecutive livebirths in British Columbia during the period 1952-1984 was studied using the records of a population-based registry with multiple sources of ascertainment. There were 18 cases of amelia, giving a minimal incidence rate of 0.15 per 10,000 livebirths for this birth defect. Amelia occurred equally frequently in upper and lower limbs, and 11 of 18 (61%) liveborn cases also had malformations of other organ systems. In the group with lower limb amelia a specific pattern of associated malformations, which included omphalocele and diaphragmatic defects, was identified. There was no evidence for familial recurrence of amelia. Conditions to be considered in differential diagnosis are discussed.     

心电向量均值数学模型及其Matlab实现

目的:探讨健康人群心电向量活动规律,建立带有标准差的QRS环心电向量均值数学模型,运用Matlab软件编写心电向量模型的标准源代码程序,为临床诊断领域提供科学理论依据和实现方法.方法:运用概率论与数理统计理论,抽取样本数据并进行统计分析,利用数学建模理论、借助数学软件Matlab的可视化功能实现数形转换,绘制带有标准差边界的心电向量曲线.结果:样本心电向量数据变化具有一定统计规律,QRS环具有在第一卦限(或象限)集中的趋势.心电向量活动规律与性别有关.结论:心电向量均值数学模型既能比较地准确反应出健康人群心电向量活动规律,同时模型也能较好检测出心脏病患者的异常状况.模型的使用范围可以推广到其他健康人群.该模型不仅为临床诊断提供科学的理论依据,也为心电向量四维数学模型的构建奠定坚实的理论基础。     

Comparative studies on the wide frequency band electrocardiogram and vectorcardiogram in pigeon and mouse

Wide frequency band ECG and vectorcardiogram in anesthetized pigeon and mouse were studied from the standpoint of comparison. The key results were as follows: in pigeon, the direction of the main QRS was inverted in leads II, III and aVF, and upright in lead aVR, which was contrary to that in mouse. The T wave was upright in leads II, III and aVF, but inverted in lead aVR in pigeon, which was the same as that in mouse. In pigeon, there was a large notch on the upstroke of the S wave in lead II without exception, but there was no such notch in the corresponding lead in mouse. The QRS vector loop in the frontal plane lay between -90 and -180 degrees in pigeon, while that of mouse lay between 0 and 90 degrees. The relative power of high frequency range (80-1000 Hz) of the QRS in lead II was approximately 15% in pigeon, but 55% in mouse. The direction of the main QRS was contrary in pigeon and mouse because the subepicardial muscles were depolarized before the subendocardial muscles in pigeon, but the latter were depolarized before the former in mouse. The direction of the T waves was the same in both pigeon and mouse because subepicardial muscles were all repolarized before subendocardial muscles.     

Changes in dynamic exercise performance following a sequence of preconditioning isometric muscle actions

Complex training is the method of coupling heavy and light loads into an organized sequence with the aim of facilitating postactivation potentiation. Anecdotal evidence has supported the use of complex training sequences, but scientific studies investigating the effects of sequencing isometric loads with dynamic muscle actions have been limited. The purpose of this study was to examine the effects of a preconditioning sequence of maximal isometric knee extensions on performance standards in selected dynamic whole-body exercise. Fourteen track and field athletes (23 +/- 5.7 years; 71.53 +/- 6.93 kg; 172.6 +/- 5.8 cm) were randomly assessed in selected whole-body exercises (drop and countermovement jumps, 5-second cycle sprint, knee extension) following a sequence of maximal voluntary isometric contractions (MVC; 3 repetitions of 3 seconds or 3 repetitions of 5 seconds) or in the absence of prior loading (control). Electromyographic (EMG) assessments of muscle activity were also made during the knee extension assessment. Significant (p < or = 0.05) increases in jump height (5.03%), maximal force (4.94%), and acceleration impulse (9.49%) were observed in the drop jump following 3 repetitions of 3-second MVC only. Knee extension maximal torque was also significantly increased (6.12%) following the 3-second MVC. No significant changes in countermovement jump or cycle sprint measures were observed for any of the experimental conditions. Though adaptations were found, changes in EMG activity were not significantly different for any of the experimental conditions. These data indicate that performing a sequence of repeated maximal isometric knee extensions (3 repetitions of 3 seconds) prior to selected dynamic exercise (< or =0.25 seconds) may have favorable effects on performance beyond standards achieved without prior heavy loading.     

Ultrastructural changes in transverse striated muscles under the influence of space flight factors

The influence of space flight (on the biosatellite "Kosmos-1667") on muscles (diaphragmatic, soleus, gastrocnemius) was studied by electron microscope. Muscles had destructive and atrophic changes. The rate of changes was maximal in m. soleus, minimal in the diaphragmatic m. However, some regeneration was found demonstrating the reversibility of changes.     

Vectorcardiographic Abnormalities Simulating Myocardial Infarction in the Normal Heart

During a study of the vectorcardiogram in the normal young heart, four individuals were found in whom the QRS loops, surprisingly, fulfilled the usual criteria for the diagnosis of myocardial infarction. These vectorcardiograms are described in detail. Two of the four electrocardiograms are within normal limits. These abnormal vectorcardiographic patterns are probably due to a congenital variant in left ventricular conduction. This rare condition is of clinical significance because it may result in diagnostic confusion in older patients.     

Selective Coronary Arteriography: Arteriographic Patterns in Coronary Heart Disease

The severity and distribution of coronary arteriographic abnormalities have been reviewed in 88 patients with clinical evidence of coronary heart disease who were studied by Sones'' technique. The patients were divided into four groups: myocardial infarction without angina, myocardial infarction with angina, angina with normal resting electrocardiogram, angina with abnormal resting electrocardiogram.Arteriographic abnormalities were generally diffuse throughout the coronary circulation, and at least two vessels were involved in 84 patients. Although the frequency of lesions was similar in the four groups of patients, those with previous myocardial infarction had the highest incidence of complete obstruction. Patients with angina and a normal resting electrocardiogram showed the least severe obstructive lesions. The severity of the arteriographic abnormalities was independent of the duration of clinical symptoms, and it appears that diffuse involvement of the coronary arterial tree is usually present when symptoms develop.     

Increased diaphragmatic strength and tolerance to fatigue after bilateral lung transplantation: an electromyographic study.

We evaluated the diaphragmatic function of seven patients with severe chronic respiratory failure before and after a bilateral lung transplantation (BLT), with follow-up at one year of pulmonary function tests, maximal inspiratory mouth pressure (MIP) and surface diaphragmatic electromyogram (Edi). The patients were asked to sustain target inspiratory pressures at -15, -30, and -50 cmH(2)O. We measured the endurance time (Tlim) to sustain inspiratory efforts and the power spectrum density function of Edi at each inspiratory maneuver. The Edi power spectra was analysed in terms of median frequency (MF), total power (TP) and energies in high-and low-frequency bands (EL and EH). Before BLT, a defect of the diaphragmatic function was evident: MIP was 62+/-7% of the predicted value and the Tlim measured at each inspiratory effort was very short ( 13+/-1 s, 10+/-1 s and 8+/-1 s at pressures of -15, -30, and -50 cmH(2)O, respectively). One month after BLT, the Tlim began to increase at all target inspiratory pressures and at 6 months MIP recovered to normal values. One month after BLT, there was a significant decrease in TP measured at the beginning of each inspiratory efforts and also an increase in the concomitant MF value. BLT markedly accentuated the maximal variations of TP, MF and low-frequency Edi energy. Some hypotheses are raised to explain this dramatic improvement in diaphragmatic function after BLT.