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H V Pipberger

Publications and source records attributed to H V Pipberger.

At least 19 recordsLinked to original sources
PubMed1979

Performance of conventional orthogonal and multiple-dipole electrocardiograms in estimating left ventricular muscle mass.

For estimating left ventricular mass (LVM), ECG criteria for left ventricular hypertrophy (LVH) were selected from conventional 12-lead ECGs, orthogonal three-lead ECGs, and multiple-dipole ECGs (MDECG). The three cardiograms were recorded in 139 patients for whom the degree of LVH was independently determined from biplane ventriculograms. Tested ECG criteria included Sokolow-Lyon measurements for the 12-lead ECG; for the orthogonal ECG, maximal QRS magnitude in the horizontal plane, R duration in the z-lead and Jxyz (spatial magnitude of point J); and for the 126 leads of the MDECG, the dipole activity (DA) of the septum and the free left ventricular wall. Correlation coefficients between LVM and the 12-lead ECG, three-lead ECG and MDECG were 0.61, 0.78 and 0.89, respectively, with corresponding errors of estimated LVM of 103, 82 and 60 g. More complex recording and analytic methods clearly led to increased accuracy in LVM estimates. However, the large error of estimate may limit practical applicability of such correlations. For classification of subjects into normal and above-normal categories, a likelihood ratio was also used and led to a maximum performance index of 86% with MDECG measurements.

Electrocardiography↗
PubMed1978

Electrode position effects on Frank lead electrocardiograms.

Frank lead electrocardiograms were recorded from 149 normal and abnormal adult males using four different electrode placements. All chest electrodes were placed at: (1) the fourth intercostal space level, (2) the fifth intercostal space level, (3) the fourth intercostal space level with V4 substituted for C, and (4) the fifth intercostal space level with V4 substituted for C. Differences in mean values of many commonly used amplitudes and orientations were not statistically significant among the four recording methods, but amplitude differences for individual subjects were often large and difficult to predict. When V4 is substituted for C, as commonly done in some laboratories, Rx decreased and Rz increased by more than 10 per cent in about 40 per cent of the cases. In about 70 per cent of the cases, Rx and Rz changed significantly when electrode level was shifted from the fifth to the fourth intercostal space. For these 70 per cent, it does not appear possible to accurately predict increase or decrease of Rx, Rz, or QRSm. Analysis programs which depend on individual amplitude measurements are likely to be significantly affected by electrode placement. It is suggested that criteria for analysis programs developed using a specified version of the Frank system should ideally be applied only to electrocardiograms recorded in the same manner.

Electrocardiography↗
PubMed1978

Effects of electrode area on electrocardiographic voltages.

Effects of two different sizes of chest electrodes--100 and 750 mm2 area--on x and z Frank leads were determined using electrocardiographic data from 25 subjects. In most cases, differences in Rx and Rz were below 50 uV, but in nine cases (36%) differences exceeded this value for either Rx or Rz or both. In six cases, differences exceeded 100 uV. For an additional 20 subjects, standard precordial leads were recorded using the same two electrode sizes. QRS amplitudes were significantly affected for V4 but not for V1 or V6. Variability caused by electrode size is greater than that caused by beat-to-beat variation and is comparable to that found in day-to-day variation. Interchangeability of data among ECG recording laboratories can be significantly improved by standardizing electrode size for precordial electrodes.

Adult↗
PubMed1977

Computer analysis of the orthogonal electrocardiogram and vectorcardiogram in 257 patients with aortic valve disease.

In most electrocardiographic studies of left ventricular hypertrophy the hypertrophy has had different causes. This study examined the performance of the Frank orthogonal electrocardiogram in 257 patients with aortic valve disease, 90 with predominant aortic stenosis and the remaining 167 with predominant aortic insufficiency. Optimal measurements suggested for routine electrocardiographic diagnosis of left ventricular overload resulted in recognition of 64 percent of cases of aortic stenosis and 74 percent of cases of aortic insufficiency with a 6 percent false positive rate. Multivariate analysis techniques improved performance: 82 percent of the aortic stenosis records and 78 percent of the aortic insufficiency records were correctly recognized as showing left ventricular overload; the false positive rate was 5 percent. Although many electrocardiographic measurements were significantly correlated with the aortic valve gradient, correlations were not high enough for use in predicting the severity of the aortic stenosis. Comparison of electrocardiographic variables in aortic stenosis and aortic insufficiency demonstrated a wide overlap between groups, and the electrocardiographic changes of aortic stenosis could not be differentiated from those of aortic insufficiency.

Aortic Valve Insufficiency↗
PubMed1977

Distortions in infant electrocardiograms caused by inadequate high-frequency response.

Frank lead ECG's from infants were studied for frequency content by introducing low-pass filters of 50, 75, 100, and 150 150 Hz bandwidths before obtaining computer measurements. Results indicated that a minimum bandwidth of 100 Hz is required to avoid amplitude error of 10 per cent or greater. This bandwidth requierement is essentially the same as that required for adult ECG's despite the fact that infant QRS durations are usually about half those of adults. Although the average infant ECG spectrum is likely to contain higher frequencies than the average adult ECG spectrum, duration values for Q, R, and S waves overlap in these populations to such an extent that bandwidth requirements are practically identical.

Electrocardiography↗
PubMed1977

Computer analysis of changes in frank vectorcardiograms of 666 normal infants in the first 72 hours of life.

Frank vectorcardiograms (VCGs) were collected on magnetic tape for 666 normal newborn infants at 1, 6, 12, 24, 36, 48, 60, and 72 hours after birth and analyzed by computers. The final total included 1,337 VCGs for white babies and 413 for blacks. No previous report has been made for the normal neonate with such a large sample, and no previous substantiation exists of possible age or sex differences at this early age. This study establishes a statistically significant change in vectorcardiographic patterns over the first three days, specifically in the measurements P duration, QRS duration, maximal spatial QRS amplitude, S in lead x, and T in lead z, as well as for several time-normalized QRS vectors. (P less than or equal to .005.) Racial differences were significant for T waves in lead z. This study supports the use of vectorcardiographic standards sensitive to the age of the newborn as well as to race.

Age Factors↗
PubMed1977

Serial electrocardiograms in hypertensive cardiovascular disease.

A graphic method for depicting serial changes in electrocardiograms is described and demonstrated for patients being treated in an antihypertension clinic. For these patients, the diagnostic categories, normal, left ventricular hypertrophy, and biventricular hypertrophy, are of primary interest. For each electrocardiogram, 14 measurements are used to compute posterior probabilities for each of the three categories. A triangular grid is used to plot each set of probabilities for an electrocardiogram as one point, which by its position in the triangle can be related to the three categories simultaneously. Points representing successive electrocardiograms can be plotted in the same triangle, giving a pattern of change with time. This pattern of change has been corroborated with associated clinical information on a number of patients. This display, which can be produced quickly and efficiently on a computer graphics terminal, should be considered as a possible tool in evaluating the status of individual hypertensive patients in terms of increase or decrease of ventricular hypertrophy and the efficacy of therapeutic measures.

Aged↗