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Biomedical subjects

H T Dodge

Publications and source records attributed to H T Dodge.

At least 55 records · Page 3Linked to original sources
PubMed1983

Effect of coronary artery bypass grafting on subsequent hospitalization.

The rates of hospitalization during follow-up for a matched pair cohort of medically and surgically treated patients from the Angiography Registry of Seattle Heart Watch were compared. Medically and surgically treated patients were matched according to extent of disease, left ventricular ejection fraction, age, and 3 other survival rate-related characteristics. There was a 26% reduction in cardiovascular hospitalizations in the surgically treated patients (19%/year) compared with the medically treated patients (26%/year). This was due to a significant reduction in hospitalization rate for myocardial infarction (surgically treated patients 1.1%/year, medically treated patients 2.6%/year), and for other cardiovascular reasons (surgically treated patients 12.5%/year, medically treated patients 15.7%/year). No significant (p = 0.146) reduction occurred in hospitalization rate for chest pain not due to myocardial infarction (surgically treated patients 5.6%/year, medically treated patients 7.7%/year). When the perioperative infarctions are included for the surgical cohort, the overall myocardial infarction rate is not significantly different (p = 0.173) between the 2 treatment groups (surgically treated patients 1.9%/year, medically treated patients 2.6%/year). Acute myocardial infarction was an uncommon reason for hospitalization, accounting for only 8% (55 of 685) of all cardiovascular hospitalizations, and was not related to the number of stenotic vessels in medically treated patients.

Actuarial Analysis↗
PubMed1983

Quantitative contrast angiography for assessment of ventricular performance in heart disease.

Contrast angiography provides much information about ventricular and valvular size and function. This review describes the calculation of left ventricular chamber volume and wall thickness and the derivation of ejection fraction, cardiac output, mass and wall tension and stress. In patients with valvular regurgitation, valve orifice area can be calculated by using the angiographic output and regurgitant flow determined by comparing the angiographic output with the cardiac output measured using Fick or indicator-dilution techniques. By analyzing ventricular volume in conjunction with pressure, it is possible to assess pressure-volume work, compliance and contractility. Regional wall motion can be measured from the change in ventricular contour with time. When applied clinically, these methods and measurements have been used to determine the hemodynamic characteristics of the compensated and decompensated left ventricle in valvular and coronary heart disease. The information derived from quantifying information in angiographic images contributes to patient diagnosis, assessment of prognosis and evaluation of therapy, and has added to our knowledge concerning the pathophysiology of heart disease.

Cardiac Volume↗
PubMed1983

Variability in the measurement of regional left ventricular wall motion from contrast angiograms.

Four types of variability affecting quantification of regional wall motion from contrast left ventriculograms (LVgrams) were studied. These included beat-to-beat variability in 24 LVgrams, intraobserver and interobserver variability in 20 LVgrams, and study-to-study variability in serial LVgrams of 21 patients with stable coronary artery disease. Motion was measured at 100 equidistant chords perpendicular to a center line drawn midway between the end-diastolic and end-systolic contours and normalized for heart size. Variability was computed as the absolute difference between observations. Beat-to-beat, intraobserver, and interobserver variability at the 100 chords were similar, averaging 14%, 14%, and 17%, respectively, of the mean motion in 64 patients with normal ventriculograms. Study-to-study variability was significantly higher, averaging 30% of mean normal motion, but was reduced when regional motion was calculated as the mean motion of chords within a region of interest. Variability peaked at the apex. Realignment to correct for cardiac rotation significantly increased variability. Investigators whose methods of wall motion analysis rely on identification of the apex as a landmark should be aware of this source of potential variability and error.

Arterial Occlusive Diseases↗
PubMed1983

Value of partial ejection fraction, volume increment, and regional wall motion in identifying patients with clinically significant coronary artery disease.

Recent studies suggest that the partial ejection fraction (EF) in early systole is a more sensitive index of left ventricular (LV) dysfunction than the holosystolic EF. We examined LV volume, partial EF, and volume increment at each of 12 time points in systole to determine which parameter best distinguishes normal subjects from patients with coronary artery disease (CAD). Contrast ventriculograms, obtained either in the right anterior oblique projection (60 frames/sec) or in the biplane projection (30 frames/sec), of 58 normal subjects and 68 patients with CAD were studied. The endocardial contour in each frame of a sinus beat was traced to derive a volume curve. At each twelfth of systole, LV volume was extrapolated from the curve and the partial EF was calculated. The increment in volume between successive time points was also calculated. Both partial EF and LV volume in patients with CAD became progressively more abnormal with time; peak abnormality occurred at end-systole. In a subgroup of patients with CAD who had normal holosystolic EF, both partial EF and volume were normal throughout systole. The increment in volume with each twelfth of systole in patients with CAD deviated less than 1 SD from normal throughout systole. Thus, maximum abnormality in partial EF and volume occurs at end-systole. Of the parameters of global LV function tested, holosystolic EF best distinguishes patients with CAD from normal subjects. However, regional wall motion measured in the area of interest is more sensitive to localized abnormality, the severity of which may be overestimated or underestimated by the EF due to hyperkinesis or hypokinesis in other regions of the left ventricle.

Cardiac Catheterization↗
PubMed1982

Effect of perioperative myocardial infarction on late survival in patients undergoing coronary artery bypass surgery.

From the Seattle Heart Watch angiography registry, the baseline characteristics and late survival of 77 patients who sustained operative infarction (new Q waves) with myocardial revascularization were compared with 1790 patients who underwent coronary artery bypass without perioperative infarction. With the exception of coronary collateral vessels, which were less frequently seen in the patients with perioperative infarction, no baseline or operative characteristic distinguished between the two groups. Late survival was clearly adversely affected by perioperative infarction. Five-year survival was 76% in patients with perioperative infarction, compared with 90% in those with no perioperative infarction.

Cardiac Catheterization↗
PubMed1981

Intravenous dipyridamole combined with isometric handgrip for near maximal acute increase in coronary flow in patients with coronary artery disease.

Twenty-four patients with coronary artery disease were studied during cardiac catheterization to determine the effects of sustained isometric handgrip exercise and intravenous dipyridamole and their combination on coronary and systemic hemodynamics and measured coronary luminal caliber. During 4 to 5 minutes of 25 percent maximal handgrip, blood pressure and heart rate increased 24 and 19 percent, respectively, coronary sinus flow increased to 1.7 x baseline value, and epicardial coronary arteries constricted to increase predicted flow resistance by 40 percent in 36 diseased arterial segments. After a 4 minute intravenous infusion of dipyridamole (0.56 mg/kg body weight), systemic pressure decreased 8 percent, heart rate increased 23 percent, coronary sinus flow increased to 2.4 x baseline value and coronary luminal caliber was unchanged. During isometric handgrip initiated 6 minutes after the infusion of dipyridamole, systemic pressure and heart rate increased to 14 and 31 percent, respectively, above control values, coronary sinus flow increased to 3.3 x baseline value (3.8 x baseline value in patients with normal anterior perfusion) and stenotic flow resistance increased by 36 percent. The response of coronary flow to the combined stresses was 68 percent greater than the response to dipyridamole alone (p less than 0.02); these flow levels exceed values previously reported for the human coronary circulation. Aminophylline plus nitroglycerin appears to assure patient safety.

Acute Disease↗
PubMed1981

Comparisons of the effects on survival after coronary artery surgery in subgroups of patients from the Seattle Heart Watch.

We compared the survival of medically and surgically treated coronary artery disease patients in subgroups of patients to determine those most or least likely to benefit from surgery after an average of 5.5 years of follow-up. Cox's regression model for survival analysis was used in conjunction with data from all patients to estimate and test for the significance of the effects of surgery on survival in subgroups of patients, defined by one or more of the following variables: number of stenotic vessels (greater than or equal to 70%), ejection fraction, age, heart murmur, diuretic therapy, ventricular arrhythmia on resting ECG, left main coronary artery stenosis greater than or equal to 50%, previous myocardial infarction, cardiomegaly, congestive heart failure, unstable angina, and functional class. The Cox model adjusts for differences between medical and surgical patients in variables shown to be predictive of survival. A statistically beneficial effect of surgery on survival was seen in patients with two- or three-vessel disease, ejection fraction greater than or equal to 30%, age greater than or equal to 48 years, no heart murmur, no diuretic therapy, no ventricular arrhythmia on resting ECG, left main coronary artery stenosis less than 50%, no cardiomegaly, and no congestive heart failure. The converse subgroups defined by these variables did not show a significant beneficial effect from surgery. However, patient subgroups defined by presence or absence of prior myocardial infarction or unstable angina and New York Heart Association functional class I-II vs III-IV all showed beneficial effects from surgery.

Angina Pectoris↗
PubMed1981

The mechanisms of nitroglycerin action: stenosis vasodilatation as a major component of the drug response.

The effect of sublingual or intracoronary nitroglycerin (NTG) on luminal caliber in normal and diseased portions of epicardial coronary arteries was determined in 85 lesions from 57 typical patients with ischemic heart disease. Measurements were made from coronary angiograms, using a computer-assisted method and a carefully blinded protocol for analysis of the pre- and post- NTG angiograms. Luminal area in the "normal" portion of the diseased segment and at its maximum constriction and an estimate of flow resistance in the stenosis were computed. Luminal area increased 1.27 mm2 (p less than 0.001) in the "normal" regions, an average increase of 18% over the control area. Dilation with NTG depended strongly on vessel size; area increased 35% in normal vessels of 1.6-2.3 mm luminal diameter and only 9% in vessels 4.0-5.0 mm in diameter. Lesions were grouped into four levels of severity by percent stenosis. Minimum luminal area increased 0.35 mm2 (p less than 0.01) at the narrowest point in moderate lesions, a 22% area increase, and 0.14 mm2 (p less than 0.001) in severe lesions, a 36% area increase. Stenosis dilation resulted in an average 25% reduction (p less than 0.01) in estimated stenosis flow resistance in moderate lesions and a 38% reduction (p less than 0.001) in severe lesions. A statistically significant resistance reduction of greater than 20% occurred in 15 to 20 severe stenoses; only two of 20 showed no measurable dilation. We reviewed recent literature on hemodynamic responses to NTG and determined that changes of this magnitude are among the largest reported. We conclude that vasodilation of epicardial coronary stenosis is usually a major component of the beneficial response to NTG. We support that conclusion by demonstrating a striking improvement in ischemic left ventricular compliance abnormalities after low-dose intracoronary NTG.

Constriction, Pathologic↗
PubMed1980

Effect of coronary surgery on survival in asymptomatic and minimally symptomatic patients.

The effect of aortocoronary saphenous bypass graft surgery on survival of functional class I and II patients was studied in 619 patients entered in the Seattle Heart Watch when they had coronary arteriography. Cox's regression analysis was used to correct for differences in baseline characteristics that occur as a result of nonrandom assignment to medical or surgical therapy. For the 619 patients, surgical therapy was predictive of improved survival, with bordeline statistical significance (Z = -1.820; p = 0.069). With subgroup analysis, patients with three-vessel disease had a significantly improved survival rate (Z = -2.378; p = 0.017), but patients with one-vessel disease (Z = 0.307; p = 0.758) or two-vessel disease (Z = -0.98; p = 0.324) did not.

Adult↗
PubMed1979

Effect of surgical versus medical therapy on return to work in patients with coronary artery disease.

The proportion of medically and surgically treated patients with coronary artery disease working full time 1 year after cardiac catheterization or surgery, respectively, was assessed by questionnaire in a registry of patients who had had coronary angiography. The proportion of medically and surgically treated patients working 3 months before catheterization or surgery was 74 percent (148 of 201) and 75 percent (899 of 1,198), respectively, whereas 62 percent (125 of 201) and 62 percent (747 of 1,198), respectively, were working full time 1 year after catheterization or surgery. Multivariate analysis identified five variables predictive of return to work. In order of significance these were: working status 3 months before surgery or catheterization, years of education, age, functional class before surgery or catheterization and period of not working before surgery or catheterization. Work status 3 months before surgery or catheterization was clearly the best predictor of continued employment 15 months later. Surgical therapy was not more effective than medical therapy in maintaining full-time employment in this registry of patients with coronary artery disease.

Age Factors↗
PubMed1979

Relationship of cardiothoracic ratio and plain film heart volume to late survival.

We assessed the prognostic value of cardiothoracic ratio and plain film heart volume in relation to other clinical, exercise, hemodynamic and quantitative angiographic variables. Both cardiothoracic ratio and plain film heart volume are highly sensitive, but nonspecific, indicators of abnormal left ventricular end-diastolic volume and ejection fraction. Both variables are univariately important predictors of survival in cohorts of medically and surgically treated heart disease patients. Plain film heart volume significantly adds to the multivariate prediction of prognosis obtained from groups of clinical, exercise, hemodynamic and quantitative angiographic variables. These measurements from the routine chest roentgenogram are sensitive detectors of abnormal left ventricular function or volume and important predictors of long-term survival. The fact that they contribute prognostic information in addition to left ventricular volume and ejection fraction suggests that other cardiac chamber volumes are of prognostic importance.

Adult↗
PubMed1979

Variables predictive of survival in patients with coronary disease. Selection by univariate and multivariate analyses from the clinical, electrocardiographic, exercise, arteriographic, and quantitative angiographic evaluations.

A progression of univariate followed by multivariate analyses was applied to 46 variables selected from the clinical examination, exercise test, coronary arteriography, and quantitative angiographic assessment of left ventricular function in patients with coronary disease to determine those variables most predictive of survival. For the 733 medically treated patients, the final Cox's regression analysis showed that the left ventricular ejection fraction was most predictive of survival, followed by age, number of vessels with stenosis(es) greater than or equal to 70%, and ventricular arrhythmia on the resting electrocardiogram. For the 1870 surgically treated patients, ventricular arrhythmia on the resting electrocardiogram was most predictive of survival followed by ejection fraction, heart murmur, left main coronary artery stenosis greater than or equal to 50%, and use of diuretic agents.

Adult↗
PubMed1979

Evidence from a nonrandomized study that coronary surgery prolongs survival in patients with two-vessel coronary disease.

Within the larger Seattle Heart Watch arteriography registry, surgically treated patients non randomly selected for direct myocardial revascularization were matched to medically treated patients such that each of the 287 pairs was identical in seven variables (ejection fraction, ventricular arrhythmia on resting electrocardiogram, age, heart murmur, stenosis of left main coronary artery greater than or equal to 50%, number of vessels with stenosis greater than or equal to 70%, and use of diuretics) previously demonstrated to be independently predictive of survival. Actuarial survival analyses based on cardiovascular deaths (average follow-up 3.5 years) indicate improved survival for the entire surgical matched pair cohort (p = 0.008) and for the surgically treated subgroup with two-vessel disease (p = 0.0002) when compared to the medical cohort. These results were confirmed by examination of the entire arteriography registry (n = 1524) in which these seven variables were known, using Cox's model for survival analysis. This multivariate, statistical technique indicated that the surgical mode of therapy was significantly predictive of improved survival in surgically treated patients for the entire registry (p = 0.008) and for the subgroup with two-vessel disease (p = 0.0005).

Adult↗
PubMed1979

Quantitative coronary angiography: measurement of the "critical" stenosis in patients with unstable angina and single-vessel disease without collaterals.

Quantitative angiographic assessment of proximal coronary artery stenosis was performed in 15 patients with consecutive presentations in two categories defined by clinical and angiographic criteria. Group 1 consisted of 10 patients who had new onset of refractory rest angina and ischemic ST-T changes, but no infarction, single-vessel coronary disease without collateralization, and normal left ventricular (LV) angiograms. Group 2 consisted of five patients who were similar to patients in group 1, but had subendocardial infarction (SEI). Quantitative coronary arteriography, using paired perpendicular angiographic views and digital computation, yielded statistically different lesion dimensions and hemodynamic predictions for the two groups. Minimum stenosis diameters were 0.88 +/- 0.14 (SD) and 0.64 +/- 0.08 mm, respectively, for groups 1 and 2. This corresponded to 72% and 78% diameter reduction and 92% and 95% cross-sectional area reduction for the two groups. These small dimensional differences among lesions in the two groups resulted in large differences in their hemodynamic impact as predicted from classic fluid mechanics theory. We conclude that there are characteristic lesion dimensions for the isolated "critical" stenosis in these selected patients with rest angina. Further small increases in lesions severity result in SEI. Certain practical applications and limitations of these observations are discussed.

Angina Pectoris↗