Electrocardiographic and vectorcardiographic diagnosis of posterior wall myocardial infarction. Significance of the T wave.

The electrocardiographic diagnosis of posterior wall myocardial infarction remains elusive. To determine discriminating criteria a group of 27 patients with posterior infarction proven by biplane angiocardiography were compared to 97 controls. All patients had single-vessel obstruction of the circumflex artery or one of its major branches (greater than or equal to 75 percent area stenosis) without occlusive disease in the other coronary arteries. High-frequency, high-gain electrocardiograms and Cube and McFee vectorcardiograms were analyzed. Pathologic Q waves in the inferior leads were present in only 22 percent (six) of the patients; increased R-wave amplitude or duration in the right precordial leads was found in 17 to 26 percent, and an R/S ratio greater than or equal to I in lead V1 or greater than or equal to 1.5 in lead V2 was present in 22 percent (six) of patients. Vectorcardiographic criteria which improved the diagnostic yield were: (1) the presence of a QRS loop mostly anterior to the E point, and (2) the presence of an abnormally anterior T wave. This abnormal T-wave shift was present in over 70 percent of the patients with posterior infarctions and was clearly discernible from the 12-lead ECG, as manifested by tall T waves in lead V2 and flat T waves in lead V6. To approximate the T-wave angle in the 12-lead scalar ECG, an index was calculated by subtracting the amplitude of the T wave in lead V6 from its amplitude in lead V2 (T2-T6 index). An index of 0.38 mV or more yielded a sensitivity of 81 percent and a specificity of 75 percent; however, this was not as discriminating as the vectorcardiogram where a T angle of 60 degrees or more in the horizontal plane yielded a sensitivity of 70 percent and a specificity of 97 percent.

Neonatal lenticulostriate vasculopathy: further characterisation.

BACKGROUND: Lenticulostriate vasculopathy (LSV) is sometimes detected on routine brain ultrasonography in neonates, and is often associated with various perinatal and neonatal abnormalities. However, most reports on LSV are retrospective with no controls. OBJECTIVES: To compare the perinatal and neonatal clinical characteristics of neonates with LSV with matched controls and to summarise all published reports of LSV. DESIGN: A prospective study that summarises the clinical, laboratory, and neurosonographic data of neonates with LSV. METHODS: Of 1184 neonates admitted to the neonatal intensive care unit (NICU) during a three year period, 857 had a routine head ultrasound examination. Twenty one had LSV, and were compared with 42 matched controls with regard to gestational, perinatal, neonatal, laboratory, and neurosonographic characteristics. RESULTS: LSV was detected in 21 of the 857 (2.45%) neonates. It was bilateral in 10 of the 21 cases and located in the thalamus (n = 14) and basal ganglia (n = 7). Infants with LSV were not significantly different from matched controls in most tested variables. However, compared with the control group, the LSV group included significantly more multiple births and more disturbances in amniotic fluid volume, but less meconial amniotic fluid. In addition, the patients with LSV required fewer blood transfusions and less phototherapy. CONCLUSIONS: Except for more multiple births, neonates with LSV did not display more adverse findings than their matched controls.

Palatal exostosis in the molar region.

Six hundred and eithty-one dried human skulls of different ethnic backgrounds or localities were examined for the presence of palatal exostosis in the molar region. Of these samples, 276 (40.53%) exhibited some form of palatal exostosis. Chi-square analysis shows that the occurrence of exostosis is: (a) Dependent upon the locality in which the subject lives; (b) Influenced by age; (c) In any age group, dependent upon the locality; (d) Dependent upon the type or class of exostosis; (e) In any type, influenced by locality. The result of this investigation may become clinically important. It suggests, for the clinicians in the field of periodontics, certain diagnostic guidelines for treatment planning of periodontal surgical procedures in the palatal molar region. Thus, an awareness of the patients' ethnic background, as well as age, may be essential in order to minimize or avoid unnecessary postoperative healing complications.

Gray hair in black males a possible risk factor in coronary artery disease.

Premature gray hair has been reported to be associated with coronary artery disease (CAD) in white males. Premature gray hair also occurs in black males despite a reported lower incidence of coronary artery disease in this group. In order to determine if premature gray hair is associated with coronary artery disease in a black male population, we prospectively studied 120 patients. Forty black males with proven CAD had gray hair in 100 percent of the cases as compared to 55 percent in a control series of 80 black males. The appearance of gray hair occurred at an earlier age in the black patients with CAD. The interrelating mechanism between premature gray hair and CAD in black males is not clearly understood at this time, but we think it represents a clinically significant observation.

Coronary involvement after a single myocardial infarction. Coronary angiography study.

Coronary angiography was performed in 95 patients 3 months to 3 years after a single myocardial infarction. The patients were categorized into 4 groups according to coronary angiography findings: group I with three or four vessels diseased; group II with two vessels diseased; group III with one vessel diseased, and group IV with normal arteries. Vessel disease was considered present if 50% of the lumen was narrowed. The patient population was almost equally distributed among group I (26), group II (26), group II (33) and group III (34). Group IV included only 3 patients in this retrospective study.

A subvariant of concealed bigeminy.

A subvariant of the "even variant" of concealed bigeminy was studied in two patients. The typical pattern consisted of two types of sequences of conducted sinus beats between extrasystoles. One pattern was bigeminal, i.e., alternating sinus beats and extrasystoles. Between bigeminal sequences were intervals in which there were more than one conducted sinus beat between extrasystoles. In such longer sequences, the numbers of sinus beats were almost invariably even. In the bigeminal sequences, the coupling intervals progressively diminished for each successive extrasystole in the sequence. The proposed explanation for the subvariant was based on a reentry loop in which there were three sites of block: proximal, intermediate, and distal. Block was postulated to take place at the proximal site after those extrasystoles with the shortest coupling intervals, at the intermediate site after odd-numbered conducted sinus beats in the non-bigeminal sequences, and at the distal site ("concealment") after the even-numbered sinus beats in these longer sequences.

Effects of digoxin on the chronotropic responses to repetitive vagal stimulus bursts in the dog.

We studied the effects of digoxin on the chronotropic responses of the heart to repetitive bursts of vagal stimulation in chloralose-anesthetized dogs. The frequency of the stimulus bursts was increased linearly with time. Over a certain range of frequencies, the cardiac pacemaker became synchronized with the vagal stimulation in a 1:1 ratio of heart beats to stimulus bursts. Digoxin increased the range of cardiac cycle lengths over which 1:1 synchronization occurred during repetitive vagal stimulation. This increment in the range of synchronization varied directly with the dose of digoxin. Before digoxin was given, the range of cardiac cycle lengths over which synchronization occurred when the vagus nerve was stimulated with 10 pulses per burst was 272 +/- 50 (mean +/- SE) ms. However, after a cumulative dose of 120 micrograms/kg-1 digoxin had been given, the range of 1:1 synchronization increased to 396 +/- 32 ms. Digoxin did not appear to have a proportionately greater effect on those processes that take place in the phase of the cardiac cycle during which the pacemaker cells are maximally responsive than on those processes that occur in the phase of the cycle during which the pacemaker cells are minimally responsive. Therefore, we conclude that the augmented entrainment induced by digoxin is ascribable to its tendency to enhance the chronotropic response to vagal stimulation.

Noninvasive visualization of right coronary artery aneurysms.

2 cases of right coronary artery aneurysm visualized with M-mode and cross-sectional echocardiography are described. Echocardiographic visualization of right coronary artery aneurysms is possible when substantial dilation is located proximally.

The electrocardiogram in obesity.

The electrocardiographic abnormalities ascribed to morbid obesity were analyzed in a group of 144 patients without apparent clinical cardiovascular pathology and compared with a control group of 100 normal weight patients. Fifty-eight patients in the obese group were re-analyzed after significant weight loss and the electrocardiographic findings compared with their initial changes when they entered the program. The QRS voltage for the obese group was slightly lower than the voltage of the normal population; but in a significant number of the patients restudied after weight loss, the QRS voltage decreased (37 out of 58 patients). In inferolateral leads non specific flattening of the T wave was observed in the obese group (71/144); it became normal as they lost weight. The P and QRS axes of the obese group initially were within normal limits but more to the left; they moved slightly to the right, although still within normal limits as the patients lost weight. Two conclusions can be drawn from the study: a) low voltage is not a significant feature in the ECG of the obese and, b) the most consistent finding in obese patients is a flattening of the T wave.