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Biomedical subjects

C E Rackley

Publications and source records attributed to C E Rackley.

At least 127 records · Page 7Linked to original sources
PubMed1977

A multipurpose catheter for electrophysiologic and hemodynamic monitoring plus atrial pacing.

A new multipurpose flow-directed pulmonary arterial catheter has been developed and evaluated in 30 patients with acute cardiopulmonary dysfunction. The catheter permits monitoring of the bipolar atrial electrogram, pulmonary arterial or wedge pressure, central venous pressure, and cardiac output, plus atrial pacing. The standard Swan-Ganz thermistor-equipped catheter was modified to incorporate two ring electrodes on the shaft at 25 and 26 cm from the tip. With the pair of electrodes positioned in the right atrium at the junction with the superior vena cava, stable electrograms of high quality were recorded in all 30 subjects, some for as long as six days. These high-fidelity atrial electrograms permitted rapid and accurate diagnosis of many complex dysrhythmias in these unstable patients. Because of the limited noise in the signal of the electrogram, continuous quantitative measurements of intervals by a computerized system was feasible. Furthermore, the stable intracavitary position of electrodes provided a reliable site for atrial pacing, with pacing thresholds (2 to 12 ma; average, 5 ma) that remained stable for up to four days. Atrial pacing was used to treat sinus bradycardia, atrial tachyarrhythmias, digitalis intoxication, and ventricular dysrhythmias.

Arrhythmias, Cardiac↗
PubMed1976

Surgical versus medical treatment in disease of the left main coronary artery.

Data from 179 patients with a significant lesion of the left main coronary artery were reviewed to compare survival with and without bypass graft surgery. 149 patients were treated with bypass grafting. Of 38 patients treated medically, 24 were suitable for surgery but either had been evaluated before the widespread use of bypass grafting procedures or preferred medical treatment. Major prognostic factors in this group were comparable to the surgical patients. The survival-rate was consistently higher for the surgically treated group and differed significantly (P less than 0-02) for the total duration of follow-up. At twelve months, 89% of the surgical group were alive, but only 73% of the comparable medical group; at twenty-four months, survival-rates were 86% and 65% respectively. These findings, corroborated by other data, suggest that surgery prolongs life for these patients.

Aged↗
PubMed1976

Aortic stenosis, angina pectoris, coronary artery disease.

The data from 88 patients (pts) with aortic stenosis (AS) were reviewed to determine relationships between angina pectoris (AP) and coronary artery disease (CAD). Results of surgery performed in 81 of these pts was analyzed. All pts had coronary arteriograms, and lesions greater than or equal to 50% were considered significant. Fifty-nine pts had an aortic valve gradient measured at catheterization greater than or equal to 40 mmHg, and in 29 pts, AS was confirmed at operation. Sixty-eight pts (77%) experienced AP, and 32 had coexisting CAD (47%); 9 of 20 pts without AP had CAD (45%). There were no significant differences in the incidence of AP in pts divided into subgroups by the aortic valve gradient (40-50, 51-100, 101-200 mmHg) or age (40-59, 60-81 years). Also, no significant differences were found in the incidence or extent of CAD between the two age groups; the extent of CAD was similar regardless of the presence or absence of AP. In pts with AP (1) CAD was more likely in pts greater than or equal to 60 years of age; (2) CAD was less likely when the aortic valve gradient was greater than 100 mmHg, suggesting that AP in these pts was due to hemodynamically severe AS. All pts with 3-vessel CAD experienced AP, and the aortic valve gradient was less in these pts than in those with no CAD or less extensive CAD. In 19 pts with combined AS and CAD who had both the aortic valve replaced and a revascularization operation only 1 of pts died in the hospital, while 3 of 19 pts with combined AS and CAD who had aortic valve replacement alone died. In this study a significant number of pts with AS experienced AP, and the presence or absence of AP did not predict coexisting CAD. Coronary arteriography is recommended in the evaluation of pts greater than or equal to 40 years of age with AS. The operative mortality appears to be decreased in pts with AS and CAD who have combined surgery.

Adult↗
PubMed1976

Comparison of left and right ventricular function in acute myocardial infarction.

Pulmonary arterial end-diastolic and mean right atrial pressures were compared in 25 patients with acute myocardial infarction and in one patient with unstable angina. No consistent relationship was observed between these pressures. Simultaneous ventricular function curves relating the stroke work of each ventricle to its respective filling pressure were constructed on 34 occasions, dextran infusion or diuresis being used to alter the filling pressure. The curves from each ventricle were described mathematically by a quadratic (parabolic) function as well as by a straight line function and then compared by canonical correlation analysis. Alterations in the left ventricular function curves occurred with and without depression or right ventricular function curves. These hemodynamic measurements demonstrate that acute myocardial infarction can alter the relationship between left and right ventricular function.

Adult↗
PubMed1976

Metabolic consequences of glucose-insulin-potassium infusion in treatment of acute myocardial infarction.

Eighteen patients treated with glucose-insulin-potassium infusion for anaerobic support of acutely ischemic myocardial tissue were studied to ascertain the metabolic consequences of this therapy, for acute myocardial infarction. Twelve patients with acute myocardial infarction were treated in a conventional manner and served as control subjects. The glucose-insulin-potassium solution was composed of 300 g of glucose, 50 units of regular insulin and 80 mEq of potassium ion per liter, and was infused at a rate of 1.5 ml/kg per hour through the right atrial port of an indwelling Swan-Ganz thermodilution catheter. Serial measurements of serum electrolytes, cardiac and hepatic enzymes, glucose and osmolality were obtained every 4 to 6 hours for 4 days. Twenty-four urinary volume and potassium levels were measured daily. Pulmonary arterial end-diastolic pressure was measured hourly and the cardiac index daily for the duration of the study. Serum potassium increased to 5 mEq/liter during the infusion and to more than 6 mEq/liter after infusion in 28 percent of patients. No recognizable complications or arrhythmias accompanied this transient hyperkalemia. Potassium balance studies revealed a net total body potassium ion gain of 120 MEq during the study. The second most frequent finding was an elevation of serum glucose (mean 175 mg/100 ml); in all instances this was controlled with supplemental administration of insulin. The serum osmolality and fluid balance remained normal in all patients during the study. Serum glutamic oxaloacetic transaminase (SGOT) and fraction 5 of lactic dehydrogenase (LDH) were increased in 34 percent of the patients during the last 12 to 18 hours of the glucose-insulin-potassium infusion. Characterization of these enzymes suggested a hepatic origin for these changes. This study suggests that glucose-insulin-potassium infusion is a relatively safe procedure in which postinfusion hyperkalemia is the most serious potential complication.

Aspartate Aminotransferases↗
PubMed1976

Isosorbide dinitrate for the relief of severe heart failure after myocardial infarction.

Severe congestive heart failure secondary to myocardial infarction remains a difficult management problem. Although intravenous vasodilators and mechanical assist devices have been reported to improve the depressed hemodynamic function, these interventions are limited to the intensive care unit and cannot be used for long-term management. This study evaluates the hemodynamic and symptomatic response to sublingual administration to isosorbide dinitrate (5 to 10 mg) in seven consecutive patients with severe congestive heart failure after anterior wall myocardial infarction. Serial measurements of mean right atrial and pulmonary arterial end-diastolic pressure, mean blood pressure, heart rate and cardiac output were obtained during the control period and during the 4 hours after administration of isosorbide dinitrate. The peak response occurred approximately 30 minutes after drug administration with an 83 percent reduction in mean right atrial pressure (from 6 to 1 mm Hg, P less than 0.02), a 36 percent reduction in pulmonary arterial end-diastolic pressure (from 25 to 16 mm Hg, P less than 0.0001) and a 6 percent reduction in mean blood pressure (from 94 to 88 mm Hg (P less than 0.05). There were small but statistically not significant increases in cardiac index (from 2.3 to 2.6 liters/min per m2 and stroke work index (from 26 to 32 gm/beat per m2). The total systemic vascular resistance was reduced by 5 percent from 1,605 to 1,518 dynes sec cm-5 (P less than 0.10). The baseline heart rate of 105 beats/min was not significantly changed. The reduction in pulmonary arterial end-diastolic pressure became statistically significant (P less than 0.05) between 15 and 30 minutes after administration of isosorbide dinitrate and remained significant for 3 to 4 hours. This reduction of pulmonary arterial end-diastolic pressure to less than 22 mm Hg was associated with relief of the patients' pulmonary symptoms. The response to nitroglycerin (0.4 mg) was similar in magnitude but of much shorter duration (approximately 15 minutes for nitroglycerin versus 4 hours for isosorbide dinitrate in patients with and without congestive heart failure. The slope (calculated by dividing the change in cardiac index or stroke work index by the change in pulmonary arterial end-diastolic pressure) was significantly (P less than 0.05) depressed in the patients with congestive heart failure. These data demonstrate that the symptomatic pulmonary venous hypertension can be effectively relieved by isosorbide dinitrate without further compromising left ventricular function.

Blood Pressure↗
PubMed1976

Reduction of hospital mortality rate of acute myocardial infarction with glucose-insulin-potassium infusion.

Free fatty acids (FFA), the predominant myocardial energy substrate, are present in increased quantities immediately following acute myocardial infarction (AMI) and may cause deleterious alterations in cardiac rhythm, oxygen consumption, and mechanical performance. In an attempt to suppress FFA and simultaneously increase the availability of carbohydrate as a myocardial substrate, 70 patients with unequivocal AMI were administered a right atrial infusion of glucose-insulin-potassium (GIK) (300 gm. of glucose, 50 U. of regular insulin, and 80 mEq. of KC1 per liter of H2O) at a constant rate of 0.5 to 2.0 ml. per kilogram per hour for 48 hours. A dramatic fall in FFA (944 +/- 57 to 289 +/- 16 muEq per liter, p less than 0.0005) occurred during GIK infusion, and FFA rebounded to 420 +/- 39 muEq per liter (p less than 0.005) when GIK was discontinued. The hospital mortality rate in the 70 GIK recipients was compared to that of 64 untreated patients (controls) from the same coronary-care unit during the previous year. GIK and control groups had similar severity of infarction as assessed by prognostic scales of Killip, Peel, and Norris, respectively. The hospital mortality rate was reduced in the GIK recipients compared to the control group (11/70 vs. 19/64, p less than 0.05). In patients without history of prior myocardial infarction, the mortality rate was reduced four-fold in GIK recipients compared to controls (6 vs. 24 per cent, p less than 0.05). Complications of GIK infusion were infrequent and included chiefly hyperglycemia and hyperkalemia, both of which dictated meticulous monitoring of serum chemistries. The data suggest that suppression of plasma FFA with GIK infusion may be associated with a significant reduction in the hospital mortality rate of acute myocardial infarction.

Acute Disease↗
PubMed1976

Cardiogenic factors in the stroke syndrome.

The cardiogenic factors which may contribute to the stroke syndrome have been discussed (Table 14.7). Pathophysiological mechanisms include emboli from rheumatic coronary and congenital heart diseases. Atherosclerotic disease and hypertension can involve both intracranial and extracranial arteries. Disturbances in cardiac rhythm can significantly reduce cerebral blood flow. The development of cerebral hypoxia with resuscitation is described. Treatment of these disorders is reviewed, and the potential role of metabolic support of the ischemic tissue both with cerebral and myocardial damage has been presented.

Arrhythmias, Cardiac↗
PubMed1976

Myocardial infarction in patients less than 45 years old: acute course, angiographic findings, and long-term follow-up.

The clinical courses of 57 patients who had an acute myocardial infarction when less than 45 years of age were reviewed to identify descriptors which might be useful in selecting candidates for coronary artery surgery. Follow-up for the subgroup of 45 patients seen initially with acute myocardial infarction was 98% (44/45) complete. Those patients referred to the medical center because of complications for specifically for coronary artery surgery following recent infarction were not followed. Average duration of follow-up for survivors without coronary surgery was 45 months and ranged from 10 to 105 months. The hospital mortality for the above group was 16% (7/45). During the follow-up period, 11% (4/37) died, 51% (19/37) had angina, 19% (7/37) had congestive heart failure, 51% (19/37) returned to work, and only 43% (16/37) remained asymptomatic. Angiographic assessment of coronary artery lesions by the Friesinger method indicated moderately severe disease in these young patients. Multiple regression analysis did not reveal a reliable predictor of hospital or late death or subsequent morbidity.

Acute Disease↗
PubMed1976

Hemodynamic effects of isosorbide dinitrate vs nitroglycerin in patients with unstable angina.

The hemodynamic response to nitroglycerin administration, to sublingual or oral administration of isosorbide dinitrate, or to a placebo was evaluated and compared in 37 patients with unstable angina pectoris under resting, pain-free conditions. Patients with congestive heart failure were not included in this study. Serial measurements of mean arterial blood pressure (MAP), pulmonary arterial end-diastolic pressure (PAEDP), cardiac index (CI), and heart rate (HR) were obtained for one hour following nitroglycerin administration and for four hours following sublingual or oral administration of isosorbide dinitrate. Echocardiographic end-diastolic volume (EDV) measurements were obtained for the groups receiving isosorbide dinitrate or placebo. There was a significant (P less than 0.05 or less than 0.1) reduction of the MAP (5 to 10 mm Hg) that persisted for more than four hours following both sublingual and oral administration of isosorbide dinitrate. The changes in the PAEDP, HR, and CI following sublingual or oral administration of isosorbide dinitrate were small and not significant. In the group receiving isosorbide dinitrate sublingually, the EDV was reduced by more than 30 ml below the placebo group (P less than 0.1) for up to four hours. The effects of nitroglycerin administration were similar in magnitude but of much shorter duration (three to four hours for sublingual and oral administration of isosorbide dinitrate vs 15 to 30 minutes for nitroglycerin). These data demonstrate that the duration of the hemodynamic effects of sublingually and orally administered isosorbide dinitrate in patients with unstable angina pectoris and normal resting hemodynamics is 8 to 12 times longer than that of nitroglycerin.

Administration, Oral↗
PubMed1976

Glucose-insulin-potassium, free fatty acids and acute myocardial infarction in man.

In patients with stable coronary artery disease, a GIK solution may increase arterial glucose and the arterial-coronary sinus difference of glucose across the myocardium. In the same patients, GIK may reduce arterial free fatty acids as well as the arterial-coronary sinus difference of free fatty acids across the myocardium. As the arterial values of free fatty acids fall, so does the arterial-coronary sinus difference of free fatty acid across the myocardium, defining a myocardial threshold for free fatty acids of approximately 200 mEq/L. Glucose-insulin-potassium may lower free fatty acid values to near or below myocardial threshold in patients with acute myocardial infarction despite recurrent pain. Preliminary data suggest that GIK in the concentration and infusion rates used in this study may favorably influence survival in patients with acute myocardial infarction.

Acute Disease↗
PubMed1976

Treatment of congestive heart failure.

In treating heart failure, the physician must remain cognizant of pathophysiology as he prescribes and monitors therapy. In addition to seeking underlying and precipitating causes of the patient's heart failure, he must treat the congestive state by enhancing myocardial contractility, controlling excessive fluid retention, and reducing afterload. Figure 7 summarizes the theoretical shifts on a patient's left ventricular function curves that might occur with therapy. Left ventricular function might move from point A to point B with diuretic therapy, but overdiuresis could aggravate symptoms of low cardiac output, including postural hypotension. Digitalis would effect a shift from A to C. Isosorbide dinitrate would produce a shift from A to D in a patient not on digitalis and from C to D in a patient already receiving digitalis. Isosorbide dinitrate, in conjunction with more usual therapeutic measures, has proved clinically beneficial in the treatment of heart failure.

Benzothiadiazines↗
PubMed1975

Comparison of indices of muscle and pump performance in patients with coronary artery disease.

During diagnostic cardiac catheterization of 20 patients, 19 of whom had coronary artery disease (CAD), left ventricular (LV) performance was assessed by both muscle function indices and pump function indices. Muscle function indices included max dP/dt, Vpm, Vce5, and Vmax, the latter derived from both total pressure (TP) and developed pressure (DP) using catheter-tip manometry. Pump function indices included LV ejection fraction (EF) and percent abnormally contracting segment (ACS), determined from biplane LV angiography. Muscle and pump function indices were also compared to the presence of the S3 (ventricular diastolic) gallop. Correlations existed between EF and Vmax (TP), EF and Vpm, percent-ACS and Vmax(TP), and percent-ACS and Vpm, with r values of 0.760, 0.777, -0.884, and -0.841, respectively. Vmax(TP) and Vpm also correlated quantitatively with the presence of the S3 gallop (p less than 0.0005). Total pressure-derived muscle function indices appear to adquately describe mean LV performance in patients with CAD and ACS, but these muscle function indices are probably highly dependent upon the size of the myocardial scar.

Adult↗
PubMed1975

Effects of glucose-insulin-potassium on myocardial substrate availability and utilization in stable coronary artery disease. Studies on myocardial carbohydrate, lipid and oxygen arterial-coronary sinus differences in patients with coronary artery disease.

To assess the metabolic effects of myocardial substrate alteration in patients with coronary artery disease, glucose-insulin-potassium solution was administered intravenously for 30 minutes to 14 men with stable angiographically documented coronary artery disease. The glucose-insulin-potassium solution (300 g of glucose, 50 units of regular insulin and 80 mEq of potassium chloride per liter of water) was infused at a constant rate in each patient, but individual infusion rates ranged from 0.013 to 0.032 ml/kg per min (4 to 10 mg glucose/kg per min) in the 14 patients. Simultaneous arterial and coronary sinus samples were obtained at 15 minute intervals during a stable 30 minute control period and again at 15 minute intervals during the infusion; samples were assayed for glucose, lactate, free fatty acid and oxygen content. In all 14 patients, during the glucose-insulin-potassium infusion, arterial glucose and lactate increased and arterial free fatty acid levels fell; the magnitude of the changes in arterial lactate and free fatty acids was related to the rate of infusion. Arterial-coronary sinus differences (A-Cs) for glucose, lactate and free fatty acid levels correlated with the arterial concentrations of these substrates (r = 0.66, 0.87 and 0.79, respectively). Regression analyses demonstrated myocardial thresholds for the uptake of these substrates as follows: glucose 79 mg/100 ml; lactate 300 mu mole/liter; and free fatty acids 100 to 200 mu Eq/liter. Finally and most importantly, the reduction in A-Cs oxygen values after glucose-insulin-potassium infusion correlated with the reduction in A-Cs free fatty acid levels (r = 0.64, P less than 0.0001). This observation suggests that, in patients with coronary artery disease, glucose-insulin-potassium infusion may significantly diminish myocardial oxygen requirements by reduction of myocardial free fatty acid utilization and simultaneous enhancement of myocardial carbohydrate utilization. Myocardial substrate availability may be an important determinant of myocardial oxygen demand in patients with coronary artery disease. Infusion of glucose-insulin-potassium solution has the potential to alter myocardial substrate availability, thus improving the balance between myocardial oxygen demand and supply.

Adult↗
PubMed1975

Left ventricular function in patients with and without myocardial infarction and one, two or three vessel coronary artery disease.

Ninety-six patients with chest pain were studied to determine the relation between left ventricular function and severity of coronary artery disease in patients with and without a history of myocardial infarction. Coronary arteriography was performed obtaining cineangiograms (60 frames/sec) and large roll film angiograms (2 to 6 frames/sec) for precise definition of the coronary anatomy. The criteria for diagnosis of myocardial infarction were a typical history, a rise and fall in serum glutamic oxaloacetic transaminase levels and evolutionary S-T segment changes associated with Q waves of at least 0.03 second. Left ventricular function was assessed by measurement of left ventricular end-diastolic pressure and volume, and left ventricular ejection fraction, mass and compliance. Fifteen patients had normal findings; 81 were classified according to number of diseased vessels and presence or absence of myocardial infarction. There were no group differences in age or heart rate. Left ventricular end-diastolic pressure was abnormally increased in patients with three vessel disease and myocardial infarction. Left ventricular end-diastolic volume was increased and the ejection fraction was reduced in patients in each vessel disease group with myocardial infarction. Although ejection fraction was reduced in patients with three vessel disease without myocardial infarction, it was further reduced when infarction occurred. Left ventricular mass increased in patients with three vessel disease with or without myocardial infarction. Values for ventricular compliance were reduced in all patients with myocardial infarction and were lower in those with two and three vessel disease and infarction than in those with two and three vessel disease without infarction. These findings suggest that a previous history of myocardial infarction needs to be considered together with anatomic abnormalities of the coronary arteries in assessing cardiac performance in patients with ischemic heart disease, a previous myocardial infarction significantly alters left ventricular performance; the ejection fraction is a more sensitive measurement of left ventricular function than left ventricular end-diastolic pressure or volume.

Adult↗