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Biomedical subjects

H T Dodge

Publications and source records attributed to H T Dodge.

At least 73 records · Page 4Linked to original sources
PubMed1978

Prediction of late survival in patients with mitral valve disease from clinical, hemodynamic, and quantitative angiographic variables.

Late follow-up (average = 7.2 years) has been obtained in 249 patients with mitral valve disease who had quantitative angiographic assessment of left ventricular function at thetime of initial catheterization in the 1960s. Surgically treated patients with mitral valve disease had significantly improved survival as compared to medically treated patients with mitral disease. The subgroup with mixed mitral stenosis and regurgitation and the subgroup with moderate impairment of ejection fraction account for this improved survival in surgically treated patients, which occurred despite greater functional and hemodynamic impairment in the surgical cohorts. Using univariate life table survival analysis, ten variables were found to be predictive of survival in the medical cohort, and three in the surgical cohort. With multivariate Cox's regression analysis, end-diastolic volume and arteriovenous oxygen difference were significantly predictive of survival in the medical cohort; age was predictive of survival in the surgical cohort.

Hemodynamics↗
PubMed1978

Physiologic improvement following coronary artery bypass surgery.

In this study the effects of coronary artery bypass surgery on ventricular function were evaluated at rest by quantitative analysis of segmental wall motion on cineventriculography, and during maximal treadmill exercise by measurement of serial cardiac outputs (Fick method) with the use of indwelling pulmonary artery and radial artery catheters. The patient had single vessel coronary disease and exertional angina. Following placement of a bypass graft to the proximally occluded left anterior descenting coronary artery, and despite the presence of arterial hypoxemia secondary to interstitial pulmonary fibrosis, a striking increase in maximal cardiac output occurred, mediated by a rise in both maximal heart rate and stroke volume. In this patient, resting ventricular volumes and ejection fraction were normal both before and after surgery, but preoperative abnormalities in extent of segmental wall motion, identified quantitatively, were restored to normal after bypass grafting. These investigations indicate that bypass surgery can provide substantial physiologic benefits in addition to providing subjective relief of anginal symptoms.

Aged↗
PubMed1978

Left ventricular volume during maximal supine exercise: a study using metallic epicardial markers.

Changes in left ventricular (LV) volumes and ejection fraction between rest and maximal supine exercise were evaluated in 11 patients who had had four epicardial markers placed during coronary artery surgery. After calibrating marker distances with respect to volume (r = 0.92--0.99) over one cardiac cycle for each patient, regression equations were used to compute LV volume from marker measurements for beats before and during exercise. The response of the left ventricle to exercise and the extent of revascularization could not be predicted from resting LV volume or ejection fraction. Ten patients had normal resting end-diastolic volumes and eight had normal resting ejection fractions. With exercise, three had a rise in end-diastolic volume and four had a fall in ejection fraction. Graft patency was greater in the group with an unchanged or increased ejection fraction (86 vs 50%, P less than 0.05). Epicardial clip motion can be used to determine LV volumes and ejection fraction during supine maximal exercise in man. The revascularized ventricle with normal or nearly normal performance in studies done at rest responds by decreasing end-diastolic and end-systolic volume and by increasing the ejection fraction. Increases in volumes or decreases in ejection fraction reflect old myocardial damage from infarction, fibrosis or ischemia from incomplete revascularization.

Adult↗
PubMed1977

Effect of aortocoronary saphenous vein bypass grafting on death and sudden death. Comparison of nonrandomized medically and surgically treated cohorts with comparable coronary disease and left ventricular function.

The effect of saphenous vein bypass grafting on the incidence of sudden cardiac death and total cardiovascular death was studied by comparing the survival of subsets of surgically and medically treated patients with coronary disease who were similar in two major prognostic variables: extent of coronary disease and ejection fraction. Significant differences in some baseline variables existed between medical and surgical subgroups with similar ejection fraction and extent of coronary disease. Medically treated patients tended to be in a lower functional class, to have more extensive ventricular contraction abnormalities, to have a larger end-diastolic volume, and to have fewer distal vessels feasible for grafting. Surgically treated patients with two vessel disease and normal or moderately reduced election fraction had improved survival when compared with medically treated patients with two vessel disease and similar ejection fraction. Improved survival of borderline statistical significance was also seen in surgically treated patients with three vessel disease and moderately reduced ejection fraction. When categorized according to end-diastolic volume, surgically treated patients with two vessel disease and normal or moderately increased end-diastolic volume also had improved survival over similarly defined medically treated patients. The sudden death rates for subgroups of mecically treated patients were 1.8 to 10.9 times higher than the rates in subgroups of surgically treated patients with a comparable extent of coronary disease and ejection fraction.

Adult↗
PubMed1977

Quantitative coronary arteriography: estimation of dimensions, hemodynamic resistance, and atheroma mass of coronary artery lesions using the arteriogram and digital computation.

More accurate characterization of coronary artery lesions is needed for evaluation of short and long-term interventions in coronary disease. A method of segmental artery analysis has been developed to maximize the information obtained from coronary arteriograms. Coronary lesions are traced from two projected, perpendicular, 35 mm cineangiographic views and transmetted, in digital form, to a PDP 11/45 computer. Magnification and distortion of the image are compensated for in order to determine the actual vessel profiles, using the catheter and its location as a scaling device. The two views are matched; a spatial representation of the vessel centerline is constructed mathematically; and orthogonal vessel diameters are computed at increments along this centerline. Assuming an elliptical lumen, the absolute and percentage reduction in diameter and cross-sectional area in the stenosis are computed. More complex functions (integrated atheroma mass, Poiseuille resistance, and orifice resistance) are then calculated. The accuracy and variability of the different steps involved in lesion analysis have been determined. Dimensional accuracies of +/- 150 microns (SD) are feasible. Examples are given of patients with Prinzmetal's angina and with progressive coronary disease.

Adult↗
PubMed1977

Left ventricular mechanical efficiency in man with heart disease.

Thirty-eight adults with valvular and/or myocardial disease had heart catheterization with coronary blood flow and myocardial O2 consumption (MVO2) per 100 g measured by the nitrous oxide washout technique. Quantitative biplane angiocardiography was performed to assess left ventricular volume, mass, ejection fraction and work. Left ventricular efficiency was calculated from work, MVO2/100 g and mass. Efficiency ranged from 4 to 40% and was normal in some patients with severe ventricular pressure-volume work overloads. Total left ventricular MVO2 ranged up to 461 ml/min. Neither total MVO2 nor MVO2/100 g was significantly related to ventricular work, ejection fraction, or tension-time index. These data suggest 1) a relationship between left ventricular efficiency and myocardial function in chronic valvular or myocardial disease, 2) that efficiency may be normal in hypertrophied ventricles, and 3) that chronic increases in resting ventricular metabolic requirements are met by hypertrophy rather than by increased MVO2/100 g.

Adult↗
PubMed1977

Immediate effect of contrast medium injection on left ventricular volumes and ejection fraction. A study using metallic epicardial markers.

The immediate effect of contrast medium injection on left ventricular (LV) volume, stroke volume (SV) and ejection fraction (EF) was evaluated from postoperative LV biplane cineangiograms of 10 patients with 4-6 epicardial markers placed at the time of coronary artery surgery. After calibrating marker distances with respect to volume (r = 0.97-0.99) over one cardiac cycle for each patient, regression equations were used to compute LV volume from marker measurements for beats prior to, during and following injection. End-diastolic volumes (EDV) prior to injection ranged from 93-263 ml and did not change significantly with injection. End-systolic volumes (ESV) showed a mean decrease of 7.3 ml by beat 7 following injection; this was of borderline significance. Similarly, there was no significant change of SV or EF until beat 7 when there were small but significant increases of 6.4 ml and 0.04, respectively. The injection of moderate amounts of contrast in man does not cause significant changes in LV volume or EF through the sixth post-injection beat.

Cardiac Output↗
PubMed1977

Benefits of coronary artery bypass surgery.

More than 150,000 Americans have undergone coronary artery bypass surgery since this operation was first available on a nationwide scale in 1968. From data now available, we can better evaluate the various mechanisms by which bypass surgery has been thought to relieve anginal symptoms, and whether or not this operation improves ventricular function and increases survival. Most individuals have substantial or complete relief of angina after surgery, no longer require nitroglycerin or beta blocking agents, and are able to return to full physical and sexual activity. A bypass graft restores the capacity of a proximally obstructed coronary artery to increase its blood flow level up to fourfold more than resting levels with exertion. Also, evidence is now appearing that bypass surgery can improve survival in patients with advanced coronary artery disease.

Angina Pectoris↗
PubMed1976

Analysis of wall dynamics and directional components of left ventricular contraction in man.

The extent and rate of left ventricular wall thickening during systole has previously been shown to be a useful measure of regional ventricular function and to play an important role in the ejection of blood from the left ventricle. The relation among systolic wall thickening, the directional components of contraction, ejection fraction and force velocity measurements is therefore of interest in understanding the dynamics of contraction of the intact ventricle. This report describes a theoretical basis and method for using ventricular angiograms to quantify the separate contributions of longitudinal shortening, circumferential shortening and systolic wall thickening to overall ventricular performance in man. One hundred twenty-two patients with valvular, coronary or myocardial heart disease were studied with biplane angiocardiography during diagnostic cardiac catheterizations. The percent contribution of directional components to total work or power developed by a mid-wall equatorial element of myocardium was shown to be: longitudinal, 14 percent in normal and diseased ventricles; circumferential, 45 percent in normal, increasing to 55 percent in dilated ventricles (P less than 0.005); wall thickening, 40 percent in normal, decreasing to 31 percent in dilated ventricles (P less than 0.001). Thus, left ventricular contraction, which is expressed as systolic wall thickening, quantified separately from inward wall displacement due to mid-wall circumferential shortening, accounts for nearly half of segmental left ventricular work and power. The rate and extent of ventricular wall thickening correlated closely with ejection fraction (r = 0.92 and 0.95, respectively) and with velocity of circumferential shortening (r = 0.90 and 0.80, respectively). Previous models of ventricular and myocardial mechanics that include computations of mid-wall longitudinal and circumferential stress and strain do not appear to account for the large contribution of systolic wall thickening to the performance of the intact heart. Force-velocity relations as heretofore described may therefore be partial descriptors of myocardial function in the intact ventricle.

Angiocardiography↗
PubMed1976

Quantitative measurement of left ventricular volumes in man from radiopaque epicardial markers.

The distances between three or four radiopaque markers located on the left ventricular epicardial surface at the apex and in the region of the minor axes in 22 subjects showed close correlations with left ventricular chamber radii, length, volume and wall thickness determined from biplane angiograms over the range of stroke volume. The markers were previously placed during heart surgery. Regression equations relating the distances between epicardial markers and chamber volumes were used to predict volumes for other beats. There was close agreement of end-diastolic, end-systolic, and stroke volumes as determined by the angiographic and epicardial marker methods for premature atrial contraction beats and post premature contraction beats, and in studies performed during rest and exercise. Time-volume curves determined by the epicardial marker and angiographic methods were similar. It is concluded that epicardial marker measurements can be used to quantitate beat-to-beat left ventricular chamber volume and dimension changes.

Angiocardiography↗