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Biomedical subjects

C E Rackley

Publications and source records attributed to C E Rackley.

At least 91 records · Page 5Linked to original sources
PubMed1980

Coronary angiography soon after myocardial infarction.

We evaluated 198 consecutive survivors of acute myocardial infarction and performed selective coronary angiography in 117 of 131 (89 percent) patients who were deemed candidates for angiography by clinical criteria. Overall, left main CAD (greater than or equal to 70 percent stenosis) was found in ten patients (8.5 percent), three vessel CAD in 41 patients (35 percent), two vessel CAD in 37 patients (31.5 percent), single vessel disease in 27 patients (23 percent) and zero vessel disease in two patients (2 percent). Factors suggesting multivessel disease included older age, history of prior myocardial infarction, and post-infarction convalescence complicated by angina pectoris. Factors not discriminating between single and multivessel disease were sex, infarct extent (transmural vs non-transmural), (3) infarct location (anterior vs inferior), and post-infarction convalescence complicated by late arrhythmia or heart failure. This study demonstrates that multivessel coronary artery disease is common in survivors of myocardial infarction and is suggested by the occurrence of post-infarction angina and by the history of an antecedent myocardial infarction. Coronary angiography can be performed safely within 30 days after myocardial infarction in patients with an uncomplicated convalescence and with mild risk in those with a complicated convalescence.

Coronary Angiography↗
PubMed1980

[Coronary morphology in patients with unstable angina pectoris. Quantitative analysis of coronary angiograms before and after one year of medical treatment (author's transl)].

The purpose of this study was to quantify coronary morphology under medical therapy in patients with initially unstable angina pectoris (Propranolol, long-term nitrates). In 25 patients the extent of 69 coronary stenoses was exactly quantified with a vernier caliper (accuracy: 0.05 mm) in two successive coronary angiograms performed in each patient at approximately one year interval. The validity of the measuring technique was assessed in nine hearts in which 19 coronary stenoses were measured in the intravital coronary angiogram and then compared with the post mortem planimetric measurements of the same cross-sections after pressure fixation. This relation yielded a correlation coefficient of r = 0.87. In the patients with initially unstable angina the average degree of the stenoses in the three major coronary branches did not change significantly over the one year interval: In 27 stenoses of the right coronary artery the mean degree of obstruction averaged 79% in the initial angiogram and 84% in the second angiogram. In 26 stenoses of the left anterior descending artery the degree of obstruction was 78% and 77%, respectively and in 16 stenoses of the left circumflex artery 73% and 83%, respectively. Only 14 out of 69 stenoses (= 20%) showed a distinct progression of more than 20% area obstruction. All stenoses of 90% or more in the first angiogram (n = 6) progressed to complete obstruction within one year. In contrast, in five other stenoses we measured a regression in the degree of obstruction of more than 20%. We conclude from these quantitative measurements that the severity and the distribution of coronary lesions are similar in patients with stable or unstable angina pectoris. Coronary anatomy showed no significant change after one year of medical treatment in patients with unstable angina.

Angina Pectoris↗
PubMed1979

Unstable angina pectoris: a comparison of the costs of medical and surgical treatment.

This study compares the inpatient costs of therapy of patients with unstable angina pectoris randomized to surgical or medical therapy at the University of Alabama in Birmingham as part of the National Cooperative Study Group. For 74 patients followed up for 2 years, the mean inpatient charges were $4,728 for 22 medically treated patients, $9,528 for 34 surgically treated patients and $20,215 for 18 patients who crossed over from medical to surgical therapy. Differences among the three groups were statistically significant (P less than 0.001). Stepwise multiple regression analysis of total inpatient charges with medical and procedural factors as explanatory variables showed that a history of congestive heart failure, the number of infarctions during the period of the study, the duration of the longest anginal attack, the type of unstable angina and the type of treatment were significant predictors of total inpatient cost, with an R2 value of 0.829 (P less than 0.001). These variables explain the cost of treatment. One should not infer that they will also predict the appropriate type of treatment for patients with unstable angina. Although the cost of surgical therapy was double the cost of therapy for patients treated only medically, those medically treated patients whose therapy failed and who subsequently required surgery incurred mean costs twice those of the surgically treated patients and four times of patients who received only medical therapy. Reassessment of previous criticism of the high cost of surgical therapy is indicated.

Aged↗
PubMed1979

Glucose-insulin-potassium infusion in acute myocardial infarction. Review of clinical experience.

A solution of 300 gm of glucose, 50 units of regular insulin, and 80 mEq of potassium chloride in 1,000 ml of sterile water infused at a rate of 1.5 ml/kg of body weight per hour can alter the availability of glucose and free fatty acids to the myocardium. Clinical studies of patients receiving this infusion less than 15 hours after the onset of symptoms of acute myocardial infarction suggest a reduction in mortality, an improvement in left ventricular mechanical performance, and a reduction in cardiac irritability as beneficial effects. Swan-Ganz catheterization for hemodynamic, electrophysiologic, and metabolic monitoring is recommended. Diabetics who require insulin and patients with impaired renal function are not candidates for the infusion. Further clinical studies are required before conclusions can be reached regarding the efficacy of glucose-insulin-potassium infusion in attempts to salvage damaged myocardium.

Acute Disease↗
PubMed1979

Effect of filming projection and interobserver variability on angiographic biplane left ventricular volume determination.

Although biplane right anterior oblique-left anterior oblique (RAO/LAO) quantitative left ventricular (LV) angiography is commonly performed, justification of LV volume calculation using the area length method (originally formulated from anteroposterior-lateral (AP/LAT) angiograms) has been limited. To assess whether RAO/LAO and AP/LAT LV volumes are similar when computed by the area length method formula, we performed biplane cine LV angiography in both RAO/LAO and AP/LAT projections in random sequence in 21 patients and four LV models of known volume. LV silhouettes were drawn independently by two trained observers. Calculated angiographic volume of the models correlated almost exactly with their true volume (r = 0.999), establishing the absolute accuracy of this system. Rotation of the LV models through 90 degrees of obliquity at 10 degree increments demonstrated a mean change from true volume of only -5.4 +/- 0.7% (p less than 0.001). In the patient studies, rotation to the 30 degree RAO/60 degree LAO position was associated with significant changes in magnitude of biplane areas and long axes, but area length volume estimates were unchanged. Excellent correlation was found between area length calculated AP/LAT and RAO/LAO volumes with r = 0.90, 0.97, and 0.91 for end-diastolic volume (EDV), end-systolic volume (ESV) and ejection fraction (EF), respectively. Furthermore, interobserver agreement in volume assessment was excellent, with r = 0.98, 0.99, and 0.94 between observers for EDV, ESV, and EF, respectively. Interobserver and inter-method variability for estimates of LV volume and EF ranged from 5--10%. We conclude that when using RAO/LAO LV angiography, volume calculation by the area length method is justified.

Angiocardiography↗
PubMed1979

Usefulness and limitations of thallium-201 myocardial scintigraphy in delineating location and size of prior myocardial infarction.

In order to evaluate the usefulness of thallium-201 (201TI) myocardial scintigraphy in delineating the location and size of prior myocardial infarction, 32 patients were evaluated at a mean of 7 +/- 2 months after infarction with a 12-lead ECG, resting 201TI myocardial scintigram, biplane left ventriculogram and coronary angiograms. From the left ventriculogram, asynergy was quantified as percent abnormally contracting segment (% ACS), the percent of end-diastolic circumference which was either akinetic or dyskinetic. Using a computerized planimetry system, we expressed 201TI perfusion defects as a percentage of total potential thallium uptake. Of 21 patients with ECG evidence of prior transmural infarction, a 201TI defect was present in 20 (95%), and angiographic asynergy was present in all 21 (100%). The site of prior infarction by ECG agreed with the 201TI defect location in 24 of 32 patients (75%) and with site of angiographic asynergy in 23 of 32 patients (72%). Scintigraphic defects were present in only four of 10 patients (40%) with ACS less than or equal to 6%, but scintigraphic defects were found in 20 to 22 patients (91%) with ACS greater than 6% (p less than 0.01). Thallium defect size correlated marginally with angiographic left ventricular ejection fraction (r = -0.60) but correlated closely with angiographic % ACS (r = 0.80). Thallium defect size was similar among patients with one-, two-, or three-vessel coronary artery disease (greater than or equal to 70% stenosis), but thallium defect size was larger in patients with electrocardiographic evidence of transmural infarction (p less than 0.01) or pulmonary capillary wedge pressure greater than 12 mm Hg (p less than 0.001). Thus, resting 201TI myocardial scingigraphy is useful in localizing and quantifying the extent of prior myocardial infarction, but is insensitive to small infarcts (ACS less than 6%).

Angiocardiography↗
PubMed1979

Impaired maximal rate of left ventricular relaxation in patients with coronary artery disease and left ventricular dysfunction.

It has been suggested that the rate of left ventricular (LV) relaxation is related to the inotropic state, end-systolic fiber length and peak LV pressure, but little information is available regarding the rate of LV relaxation in patients with coronary artery disease (CAD) and LV dysfunction. To assess the rate of LV relaxation we obtained high-fidelity LV pressure measurements with manometer-tip catheters in 39 patients. The signal was analyzed by a digital computer to yield the maximal rate of pressure rise (pos dP/dt) and the maximal rate of pressure fall (neg dP/dt). Selective coronary arteriography and biplane LV angiography with determination of LV volumes, ejection fraction (EF) and percent abnormally contracting segments (ACS) when present, were performed in all patients. In 10 patients with normal LV function (EF greater than 0.50, no asynergy) mean neg dP/dt (2074 +/- 121 mm Hg/sec) was significantly (p less than 0.01) greater than in 29 patients with CAD and LV dysfunction (1695 +/- 66 mm Hg/sec). In nine patients with LV dysfunction and EF less than 0.35, mean neg dP/dt was reduced to 1405 +/- 107 mm Hg/sec, significantly (p less than 0.01) lower than in patients with normal LV function. Neg dP/dt correlated well with pos dP/dt (r = 0.75), with EF (r = 0.74), and with ACS (r = -0.74), and less well with LV end-systolic volume (r = 0.67). There was very poor correlation between neg dP/dt and peak LV pressure (r = 0.30). These data suggest that the rate of LV relaxation, as assessed by neg dP/dt, is impaired in patients with CAD and LV dysfunction, and the extent of impairment is related to the severity of the dysfunction as determined hemodynamically by pos dP/dt, and angiographically by EF and ACS. In these patients the maximal rate of LV relaxation is inversely related to LV end-systolic volume, and is not related to peak LV pressure.

Adult↗
PubMed1979

Unstable angina pectoris: an examination of modes and costs of therapy.

Debate exists over the most appropriate form of treatment for patients with unstable angina pectoris. This study examined 106 patients randomized at the University of Alabama in Birmingham as part of the National Cooperative Study Group and focuses on the phenomenon of patients who fail medical therapy and thus require late surgery, and the costs of therapy. Discriminant function analysis revealed that the significant predictors (p less than 0.01) of patients who would later require surgery were: total number of vessels diseased, angina severly, presence of congestive heart failure, hypertension, and number of years that the patient had had angina. By means of this analysis, 85% of the late surgery patients were correctly predicted. Late surgery patients averaged 2.4 diseased vessels vs 1.5 for persistent medical patients (p less than 0.01). Mean charges for the first 2 years in the study were $6,226 (SD $2,967) for persistent medical patients, $10,416 (SD $2,146) for surgery patients, and $20,059 (SD $10,748) for late surgery patients (p less than 0.001). These data indicate that surgery is clearly an expensive procedure; but that it is more expensive for late surgery patients, who have total costs that are twice as high as surgical costs and 3.5 times as high as persistent medical costs.

Alabama↗
PubMed1979

Use of blood-pool imaging in evaluation of diffuse activity patterns in technetium-99m pyrophosphate myocardial scintigraphy.

It has been suggested that diffuse Tc-99m pyrophosphate precordial activity may be due to persistent blood-pool activity in routine delayed views during myocardial imaging. To answer this question, we reviewed myocardial scintigrams recorded 60--90 min following the injection of 12--15 mCi of Tc-99m pyrophosphate for the presence of diffuse precordial activity, and compared these with early images of the blood pool in 265 patients. Diffuse activity in the delayed images was identified in 48 patients: in 20 with acute myocardial infarction and in 28 with no evidence of it. Comparison of these routine delayed images with early views of the blood pool revealed two types of patterns. In patients with acute infarction, 95% had delayed images that were distinguishable from blood pool either because the activity was smaller than the early blood pool, or by the presence of localized activity superimposed on diffuse activity identical to blood pool. In those without infarction, 93% had activity distribution in routine delayed views matching that in the early blood-pool images. The usefulness of the diffuse TcPPi precordial activity in myocardial infarction is improved when early blood-pool imaging is used to exclude persistence of blood-pool activity as its cause. Moreover, it does not require additional amounts of radioactivity nor complex computer processing, a feature that may be of value in the community hospital using the technique to "rule out" infarction 24--72 hr after onset of suggestive symptoms.

Angina Pectoris↗