Q-wave versus non-Q wave myocardial infarction: a meaningless distinction.

The whole subject can thus be summed up in two statements. 1. Every appropriately designed study comparing first Q and NQMI's has found no difference in post-MI course of the two categories and no foundation for the common notion that the NQMI is a uniquely "unstable" entity, to be classed with unstable angina in terms of prognosis and management. Nine such studies have been published. On the other hand, all studies alleging the "unstable" character of the NQMI have been invalidated by major flaws, chief among them the comparison of undifferentiated mixtures of first and subsequent infarcts with widely differing mortality and morbidity. This confusion is further compounded by the fact that subsequent infarcts generate Qwaves less than half as often as first infarcts. 2. All current studies indicate that there is no benefit to an invasive as compared with a conservative protocol for management of NQMI. Since the characterization of an infarct as "non-Q' conveys no therapeutic implications, the classification becomes irrelevant and should be discarded. Two quotations sum the whole matter succinctly. Moss (63) commented that "The Q-wave versus non-Q-wave categorization does not provide sufficient sensitivity, specificity, or predictive accuracy about the subsequent clinical course of patients with a first myocardial infarction to use it as reliable data in the clinical decision-making process." Surawicz (64) put the matter even more concisely: ". . . a non-Qwave MI is not a unique entity: rather it is a smaller and less extensive MI." In a word, the magnitude of a myocardial infarction should be judged on anatomical and functional considerations rather than on the designation of Qwave versus non-Qwave infarction.

Torsade de pointes and low-dose oral haloperidol.

Haloperidol, used to treat patients with psychoses, is considered minimally cardiotoxic. Several cases of torsade de pointes have been reported in association with the use of oral haloperidol. In each of those cases, a prolonged QTc preceded the torsade de pointes episode and thus may be considered a predictor for ventricular arrhythmias in elderly women treated with haloperidol. However, the following case may demonstrate the inability to predict an episode of torsade de pointes with low-dose oral haloperidol use.

One heart, two bodies: insight from the transplanted heart and its new electrocardiogram.

Cardiac transplantation provides a unique opportunity to record the electric field generated by a human heart in a new somatic environment. By examining pre- and posttransplantation electrocardiograms (ECGs), it is possible to address questions on the effect of rotation of the heart on its long axis on the surface ECG, the effect of thoracic anatomy on ECG voltage and predisposing factors for conduction defects observed after transplant surgery. To examine these questions, we reviewed a series of 35 matched donor and recipient ECGs. There were no differences in the mean height of the donors and recipients, but age, weight and body surface area were higher in the recipients (p less than 0.025). We found no significant differences in the mean heart rate or precordial voltage but the PR and QT intervals were shorter (p less than 0.025), and the precordial transitional zone was more to the left after transplantation (p less than 0.0005). New evidence of right bundle branch delay was found in 11 recipients and this was not related to pretransplantation hemodynamic factors or the period of ischemic arrest. Thus, there is indeed an anatomic basis for the ECG determination of clockwise rotation of the heart when the precordial transition zone is to the left. Age and body habitus, per se, do not appear to affect precordial voltage and evidence of right bundle delay in the transplant recipient appears to be related to the altered position of the heart and not to injury or changes in right ventricular hemodynamics.

Vectorcardiographic and blood pressure correlates of obstructive pulmonary diseases in a community population.

Vectorcardiography was performed on 2,449 subjects, aged six years and older, in the Tucson (Ariz) Epidemiological Study of Airway Obstructive Diseases (AOD), 95 percent of the white non-Mexican Americans in the stratified cluster population sample. The objectives were to confirm previous relationships and to determine if hypothesized changes in the vectorcardiogram (VCG) could predict AOD. Trained nurse technicians performed the VCGs, which were read and interpreted by a cardiologist. Vectorcardiographic results were broadly interpreted for abnormalities. Also, calculated vector means and angles were compared to standard questionnaire responses for medical history, to maximum expiratory flow-volume variables, and to values for blood pressure; these were all corrected for sex, age, height, weight, and the ponderal index. Values were expressed as percentages of predicted. Over 80 percent of the VCGs were found to be normal. Measured hypertrophy was related to disease; there were significantly more abnormalities in those with histories of heart disease, hypertension, arteriosclerosis, and AOD, when examined by types of ventricular hypertrophy and VCG-identified heart disease or hypertension; findings of AOD and heart disease were also correlated significantly. Of all the ventricular hypertrophy, right ventricular hypertrophy (RVH), type C, was confirmed to be the predominant type associated with decreased pulmonary function in all smoking groups. Systolic blood pressure was related to RVH, type A, and diastolic 4 and 5 blood pressure with RVH, types A and B. The vectors' magnitude and angles were related to abnormality of pulmonary function in those with and without heart disease and AOD.

Electrocardiographic axis deviation in Navajo and Apache indians.

It has been our clinical impression that the range of the mean frontal-plane electrocardiographic QRS axis was greater than might have been anticipated in healthy Navajo and Apache Indians. To determine whether this clinical impression was correct, electrocardiograms were obtained from 146 Navajo, 144 Apache, and 159 non-Navajo non-Apache schoolchildren with normal findings on cardiovascular examinations. A mean frontal-plane QRS axis between -1 degrees and -90 degrees was present in 19 percent of the Navajo, 12 percent of the Apache, and 2 percent of the control schoolchildren. A mean frontal-plane QRS axis between +91 degrees and +180 degrees was present in 18 percent of the Navajo, 19 percent of the Apache, and 5 percent of the control schoolchildren. There is a high incidence of electrocardiographic mean frontal-plane QRS axis deviation in healthy Navajo and Apache schoolchildren.

The differential diagnosis of bigeminal rhythms.

Bigeminal rhythms may arise from ectopic firing or from failure of impulse generation or conduction. In atrial bigeminy a premature atrial beat beat follows each sinus beat. If the PAC is not conducted bradycardia may result; if it is symptomatic treatment with digitalis or quinidine is indicated. Junctional bigeminy may be coupled to sinus beats or may accompany atrial fibrillation. Ventricular bigeminy, the most common type of bigeminy involving ectopic firing, usually requires treatment with suppressive drugs. Concealed bigeminy manifested as PVCs separated by an odd number of sinus beats has the same clinical implications as ventricular bigeminy. Re-entrant premature beats may also be triggered by an artificial ventricular pacemaker. Bigeminy associated with delayed impulse conduction is most often caused by a 3:2 Wenckebach block at the A-V junction but the block may also be at the S-A node or around an ectopic pacemaker. Conduction or production delay may produce "escape-capture" bigeminy in which successive beats are produced by the dominant pacemaker and an alternate one. Implantation of an artificial pacemaker may be appropriate. It is important for the observer to be able to identify the mechanism of any bigeminal rhythm since crucial clinical decisions may attend such identification.

Experience of a Wyoming county streptococcal control project.

Figures from Natrona County, Wyoming, during the period 1957-1959 and from the Papago Indian Health Service in Arizona during the years 1970-1982 indicate that a vigorous control program targeted to school children that used throat culturing to detect group A streptococci and to recommend adequate treatment effectively lowered the incidence of first attacks of rheumatic fever. Statistics from the Wyoming Department of Public Health for the years 1972-1983 recorded a consistently lower rate of rheumatic fever in Natrona County, where such a control program was maintained, than for the rest of the state, although the national decline in rheumatic fever incidence makes these figures more difficult to assess. Experience gained in these programs may be valuable for third world countries where rheumatic heart disease is still a major cause of death and disability.

Indications for pacing in the treatment of bradyarrhythmias. Report of an independent study group.

Indications for permanent pacing in the bradyarrhythmias are summarized. In the absence of symptoms, pacing is justified only when Mobitz type II block or complete atrioventricular (AV) block is localized in the bundle-branch system. All other abnormalities of impulse generation or conduction (incomplete AV block of any type, atrial fibrillation with slow ventricular response, or sinus node dysfunction) must be shown to be stable and intrinsic and to cause CNS symptoms or hemodynamic compromise to justify pacing. Isolated intra-Hisian abnormality without failure of AV conduction is benign. Measurement of HV interval does not contribute significant information. Correlation of carotid sinus sensitivity with carotid sinus syncope is poor (5%). Bradyarrhythmia produced by minimal effective doses of an essential drug is a rare indication for pacing and requires special documentation. Inadequate indications, sources of error, and misconceptions are discussed. Generally, it is important to exclude drug effect, transient clinical states, and correctable systemic disease as causes of the abnormality before making a conclusion about pacing.