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Biomedical subjects

H R Phillips

Publications and source records attributed to H R Phillips.

83 records · Page 5Linked to original sources
PubMed1982

Evaluation of a QRS scoring system for estimating myocardial infarct size. II. Correlation with quantitative anatomic findings for anterior infarcts.

The ability of an independently developed QRS point score to estimate the size of infarcts predominantly within the anterior third of the left ventricular was evaluated by quantitative pathologic-electrocardiographic correlation. The study was limited to 21 patients with a single infarct documented by postmortem examination, for whom an appropriately timed standard 12 lead electrocardiogram was available that did not exhibit signs of left or right ventricular hypertrophy, left or right bundle branch block or anterior or posterior fascicular block. At necropsy the heart was cut into five to seven slices. The location and size of the infarct was quantitated by computer-assisted planimetry of the slices. The electrocardiogram of 19 (90 percent) of the patients exhibited either a Q wave or an R wave of no more than 20 ms in lead V2. The infarct in the two patients without this electrocardiographic finding was small, occupying 2 and 3 percent of the left ventricle, respectively. The percent infarction of the left ventricle correlated with the QRS point score (r=0.80). Thus in patients without complicating factors in the electrocardiogram and with a single infarct, the electrocardiogram provides a marker for infarction in the anterior third of the left ventricle and permits estimation of infarct size.

Adult↗
PubMed1982

Anatomic and prognostic implications of an early positive treadmill exercise test.

Eighty men (group A) with clinical coronary artery disease underwent coronary angiography regardless of symptoms and previous therapy because they had a positive treadmill exercise test in stage I or II of the Bruce protocol. Thirty-four other men (group B) who also had an early positive treadmill test underwent coronary angiography because they had disabling angina pectoris despite medical therapy. We found left main coronary artery stenosis of 50% or greater of the vessel diameter in 28% of group A and 35% of group B (p greater than 0.3). In contrast, only 10% of 93 other catheterized patients who had treadmill tests that were not early positive had left main coronary disease (p less than 0.001). Fifty-four patients from group A who did not have left main stenosis of 50% or greater were treated medically. In this subgroup, 85% had 2 or 3 major coronary vessels with 75% or greater stenosis. These patients had a 36 month survival rate of 89.2%. We conclude that an early positive treadmill test identifies patients who have an increased likelihood of having left main coronary stenosis, even if they are minimally symptomatic. To identify left main coronary stenosis, catheterization may be justified in patients whose angina pectoris has been mild or not intensively treated when they have an early positive treadmill response. After left main coronary stenosis has been excluded, these patients may be treated medically with a low mortality.

Adult↗
PubMed1982

Hemodynamic effects of the antiarrhythmic drug pirmenol.

We examined the hemodynamic effects of pirmenol, a new antiarrhythmic drug, for the first time in man. Right and left heart pressures, Fick cardiac output, and radionuclide ejection fraction were measured before and during infusion of pirmenol in 10 patients with coronary artery disease who were undergoing routine diagnostic cardiac catheterization. Pirmenol was given as a 50-mg IV injection over 2 min followed by a constant infusion of 2.5 mg/min for up to 36 min. Plasma pirmenol levels were within or near the previously determined therapeutic range in all patients. There were no significant changes in systolic blood pressure or cardiac output. Diastolic blood pressure rose from a mean (+/- SD) 78 +/- 7 during the control period to 82 +/- 6 during the infusion, heart rate rose from 66 +/- 6 during the control period to 75 +/- 7 during infusion and ejection fraction fell from 60 +/- 8 during control to 55 +/- 12 during infusion. Although the left ventricular end-diastolic pressure rose from 6 +/- 2 during control to 8 +/- 3 during the infusion, the left ventricular stroke work index fell and the left ventricular work index per minute did not change. The fall in ejection fraction did not correlate with the control ejection fraction, plasma pirmenol levels, or the change in heart rate. The decline in ejection fraction and the failure of the left ventricular work index per minute to rise despite a small rise in left ventricular end-diastolic pressure may indicate a potential myocardial depressant effect of pirmenol.

Anti-Arrhythmia Agents↗
PubMed1982

Subvalvular thrombotic obstruction of an aortic porcine heterograft.

A 48-year-old man had angina pectoris and symptoms of heart failure. Cardiac catheterization showed severe aortic stenosis and regurgitation, and he underwent aortic valve replacement in 1976 with a 23-mm Carpentier-Edwards aortic porcine heterograft. Initially there was symptomatic improvement, but one year later the patient had the onset of dyspnea and exertional chest pain that became progressively more severe over the next three years. Repeat cardiac catheterization was performed 45 months after valve implantation, and a 76 mm Hg peak to peak and a 44 mm Hg mean systolic gradient across the aortic bioprosthesis were recorded. The porcine heterograft was surgically explanted and found to be obstructed by a subvalvular thrombus that appeared to arise from the junction of the aortic and mitral valve annuli.

Aortic Valve↗
PubMed1981

Mitral valve replacement for isolated mitral regurgitation: analysis of clinical course and late postoperative left ventricular ejection fraction.

One hundred five patients underwent mitral valve replacement for relief of isolated mitral regurgitation between 1974 and 1979. There were 4 in-hospital deaths (4 percent) and 12 late deaths giving an 82 percent predicted 5 year survival rate. An age of 60 years or more at the time of surgery and a preoperative left ventricular ejection fraction of less than 0.40 were the only variables that correlated with decreased survival at 3 to 5 years after operation (p less than 0.05). Postoperatively, 87 (98 percent) of 89 long-term survivors were in New York Heart Association functional class I or II (68 in class I and 19 in class II). Survival did not differ between patients with porcine versus mechanical valve replacement, but patients with a mechanical valve had a greater incidence of postoperative cerebrovascular accident (8.6/100 patient years) than did patients with a porcine valve (2.8/100 patient years) (p less than 0.002). Ejection fraction at rest was determined with multigated cardiac imaging 12 to 75 months postoperatively in 34 of 89 long-term survivors. The mean preoperative ejection fraction was 0.62 +/- 0.09 (mean +/- 1 standard deviation) and the mean postoperative ejection fraction was 0.50 +/- 0.15 (p less than 0.001). When the preoperative value was compared with the postoperative value at rest the ejection fraction increased by 0.10 or more in 1 patient (3 percent), remained within +/- 0.09 of the preoperative value in 12 patients (35 percent) and decreased by 0.10 or greater in 21 patients (62 percent). Sixteen (94 percent) of 17 patients whose postoperative ejection fraction was greater than 0.50 were in functional class I postoperatively compared with 11 (65 percent) of 17 patients whose postoperative ejection fraction was 0.50 or less (p less than 0.05). No preoperative factor, including preoperative ejection fraction or cardiothoracic ratio, predicted the postoperative ejection fraction. A postoperative exercise ejection fraction was obtained in 29 patients, and an abnormal ejection fraction change with exercise (increase less than 0.05) was observed in 20 patients (69 percent). Patient age at the time of study correlated inversely with the change in ejection fraction from rest to exercise; no other variables were predictive. It is concluded that, in addition to age, only preoperative left ventricular function as measured by ejection fraction predicts survival in patients undergoing mitral valve replacement for isolated mitral regurgitation. Clinical recovery is good even though the majority of long-term survivors have a postoperative decrease in ejection fraction.

Aged↗
PubMed1981

Aortocoronary bypass grafting in patients without left main stenosis. Relation of risk factors to early and late survival.

Three-hundred and thirty-five patients without left main stenosis or recent acute myocardial infarction underwent isolated aortocoronary bypass grafting during 1974 and 1975. The hospital mortality was 2 per cent for the four-year predicted survival is 94 per cent. Neither the preoperative presence or absence of a progressive or unstable angina pattern, the extent of coronary artery disease, nor the left ventricular ejection fraction predicted postoperative survival. None of the 25 patients whose ejection fraction was 0.30 or less died in the perioperative period, and no late deaths occurred in this subgroup until after 36 months of follow-up, giving a predicted four-year survival rate of 82 per cent. With only one exception, patients in this subgroup were operated on because of angina, which was unstable in three-quarters of them. We believe that this study shows that patients with a severely reduced ejection fraction should not be refused aortocoronary bypass grafting if symptoms of angina are severe and predominate over symptoms of heart failure.

Coronary Artery Bypass↗
PubMed1981

The effect of pulsatile perfusion on preservation of left ventricular function after aortocoronary bypass grafting.

Pulsatile perfusion has been reported to be of value in intraoperative myocardial protection. To evaluate this technique, we studied 26 patients undergoing aortocoronary bypass grafting. Ejection fraction determinations from multigated cardiac blood pool scans, serial hemodynamic monitoring, and total CPK and MB-CPK sampling were performed early (4, 6 and 8 hours after bypass) and 10 days after operation. In 12 patients, pulsatile perfusion was started immediately after aortic cannulation and continued until 10 minutes after cessation of bypass; 14 patients had standard nonpulsatile perfusion. All patients had a single aortic cross-clamping and potassium cardioplegia. Cross-clamp time (46 +/- 3 and 46 +/- 3 minutes [+/- SEM]), total bypass time (94 +/- 4 and 89 +/- 6 minutes), and mean perfusion pressure (82 +/- 5 and 83 +/- 3 mm Hg) were comparable in the pulsatile and nonpulsatile groups, respectively, as were extent of coronary disease and number of bypass grafts. Preoperative and postoperative ejection fractions for pulsatile and nonpulsatile groups, respectively, were 0.57 +/- 0.03 and 0.55 +/- 0.04 before operation, 0.37 +/- 0.03 and 0.40 +/- 0.04 4 hours after bypass, 0.40 +/- 0.03 and 0.46 +/- 0.04 at 6 hours, 0.51 +/- 0.05 and 0.52 +/- 0.07 at 8 hours and 0.56 +/- 0.05 and 0.53 +/- 0.04) 10 days after operation. Mean arterial pressure, left atrial pressure and serial cardiac indexes were similar in both groups. There were no perioperative myocardial infarctions by ECG in either group. Total CPK (586 +/- 78 and 617 +/- 140 IU/l) and peak MB-CPK (73 +/0 14 and 61 +/- 11 IU/l) were comparable in the pulsatile and nonpulsatile groups, respectively. Pulsatile perfusion offers no advantage in myocardial preservation after aortocoronary bypass grafting in patients with normal left ventricular function.

Coronary Artery Bypass↗
PubMed1976

Evaluation of vectorcardiographic criteria for the diagnosis of myocardial infarction in the presence of left ventricular hypertrophy.

Vectorcardiograms (VCG) from a consecutive group of 77 patients with significant aortic valve disease were analyzed. All of the patients had complete left and right heart catheterization with normal coronary arteriograms and normal left ventricular contraction. Thirty-five (46%) patients met VCG criteria for anterior myocardial infarction (AMI-35%) and/or inferior myocardial infarction (IMI-14%). This was a significant increase in false positive diagnosis for both criteria compared to a group of 200 normal volunteers under age 30 and 100 patients with normal hearts by cardiac catheterization (P less than 0.01). It was found that if the VCG diagnosis of myocardial infarction was deferred when the maximal transverse plane magnitude was greater than 1.9 mV, the incidence of AMI false positive diagnosis decreased to 3% and the incidence of IMI false positive diagnosis decreased to 1%. The same rule was applied to the aortic valve disease cohort, a group of 124 patients with documented AMI and a group of 158 patients with IMI. This decreased the sensitivity of the AMI criteria from 93 to 83% and of the IMI criteria from 85 to 77%. The increase in average performance was statistically significant fro the AMI criteria (P less than 0.05) but not for the IMI criteria.

Adult↗