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Biomedical subjects

R Roberts

Publications and source records attributed to R Roberts.

At least 541 records · Page 30Linked to original sources
PubMed1980

The effect of intravenous nitroglycerin on coronary blood flow and infarct size during myocardial infarction in conscious dogs.

Nitroglycerin (TNG), based on electrocardiographic evidence, has been shown to reduce myocardial ischemia, but its effect on morphometrically and enzymatically estimated infarct size has not been defined. Accordingly, coronary occlusion was produced in 50 conscious dogs without LV failure. Twenty-five received TNG (200-300 micrograms/min i.v. for 8 h) and the results compared with those in 25 untreated dogs. Coronary blood flow was measured with 141Ce, 85Sr, and 95Nb (9 microns) after occlusion before TNG, 30 min after TNG, and again at 8 h. Mean blood pressure decreased from 103 to 84 mmHg with TNG vs. 99 to 94 mmHg in controls (p < 0.02). Average heart rates were similar [135 +/- 26 vs. 120 +/- 33 beats/min (SD)]. TNG Did not increase total transmural coronary flow in any region but increased subendocardial flow in the central ischemic areas by 45% (0.09 ml/min/g vs. 0.13 ml/min/g). Animals were sacrificed after 24 h. Infarct size estimated morphometrically (25 +/- 1.5 vs. 26 +/- 1.5 of LV weight) and from myocardial CK depletion (23 +/- 2 vs. 23 +/- 2) was similar for the two groups. Thus, despite increased subendocardial flow, prolonged i.v. TNG did not decrease infarct size even though a difference of 15% would have been detected with this sample size. TNG May relieve coronary spasm but does not appear to be beneficial with sustained coronary occlusion.

Animals↗
PubMed1980

The effects of intravenous nitroglycerin on hemodynamics, coronary blood flow and morphologically and enzymatically estimated infarct size in conscious dogs.

Nitroglycerin (TNG) decreases ST-segment elevation accompanying myocardial ischemia, but its effect on morphometrically and enzymatically estimated infarct size (IS) has not been defined. Accordingly, coronary occlusion was produced in 92 conscious dogs; 65 survived for 24 hours. Thirty-three received TNG (200-300 microgram/min i.v. for 8 hours) and the results were compared with those in 32 untreated dogs. Coronary blood flow (CBF) was measured with tracer microspheres (141Ce, 85Sr and 95Nb) 5 minutes after occlusion before TNG, 20 minutes after TNG and again at 8 hours. Mean blood pressure decreased from 103 to 84 mm Hg with TNG, vs 99 to 94 mm Hg in controls (p > 0.02). Nitroglycerin increased CBF in the subendocardium of ischemic areas by 45% (0.09 to 0.13 ml/min/g). The dogs were sacrificed after 24 hours and IS was estimated morphometrically (25 +/- 1% vs 27 +/- 1% of left ventricular weight) and from myocardial CK depletion (23 +/- 1% vs 24 +/- 1%) were similar for the two groups. Thus, despite increased subendocardial CBF, prolonged i.v. TNG did not decrease infarct size, although a 15% difference would have been detected with this sample size. TNG may relieve coronary spasm but does not appear to be beneficial with sustained coronary occlusion.

Animals↗
PubMed1980

Dobutamine vs furosemide in the treatment of cardiac failure due to right ventricular infarction.

A 55-year-old man with acute inferior myocardial infarction was shown to have right ventricular involvement based on elevated jugular venous pressure, prominent A waves, and Kussmaul's sign. The ECG showed ST segment elevation in V3R with evolution of Q waves in the inferior leads. Technetium pyrophosphate images showed focal uptake in the inferior region of the left ventricle, and a radionuclide ventriculogram showed a dilated right ventricle. Administration of dobutamine, a potent inotropic agent, was associated with marked hemodynamic improvement. In contrast, the administration of diuretics was associated with hemodynamic impairment.

Blood Pressure↗
PubMed1980

Elevation of plasma MB creatine kinase and the development of new Q waves in association with pericarditis.

A 64-year-old woman with an acute exacerbation of chronic relapsing pericarditis had initial clinical and ECG features that were consistent with an acute anterior myocardial infarction. Transient Q waves were observed in the precordial leads, and she also exhibited elevated plasma MB creatine kinase (MB CK) activity. However, the overall clinical and laboratory data, including angiographic and radionuclide studies, suggest that the myocardial damage was secondary to pericarditis per se, rather than ischemic myocardial infarction. This case emphasizes that Q waves and elevated MB CK activity can be seen in association with pericarditis, and this must be differentiated from myocardial infarction secondary to coronary artery disease.

Creatine Kinase↗
PubMed1980

Plasma creatine kinase isoenzyme determinations in infants and children. Characterization in normal patients and after cardiac catheterization and surgery.

In adults, plasma elevations of creatine kinase isoenzymes are highly specific for myocardial necrosis, however, the diagnostic sensitivity and specificity of MB CK in children have not been determined. Accordingly, we analyzed the CK isoenzyme activity in serial plasma samples from 147 patients, aged 2 days to 18 months. Forty-two patients underwent routine checkups and served as controls. Fifty-seven patients underwent cardiac catheterization for congenital heart disease, an additional 16 underwent non-cardiac surgery, and 32 cardiac surgery. Blood samples were obtained prior to surgery and catheterization and q6H x 3 thereafter. Total plasma CK and MB CK in normals averaged 62 +/- 22 (SD) and 1.7 +/- 0.8 IU/L respectively. Despite a fivefold increase in total plasma CK after catheterization and surgery, MB CK remained normal. After cardiac surgery, total CK increased from 68 +/- 18 to 905 +/- 231 IU/L, and MB CK increased from 1.7 +/- 0.6 to 13 +/- 7 IU/L. Thus, MB CK is specific for cardiac injury and would be a valuable adjunct in the diagnosis of myocarditis or in assessing interventions to minimize cardiac injury during surgery.

Cardiac Catheterization↗
PubMed1980

Lymphocytic thyroiditis with spontaneously resolving hyperthyroidism (silent thyroiditis).

Spontaneously resolving hyperthyroidism (SRH) is a transient form of hyperthyroidism characterized by a painless, nontender, normal-sized or slightly enlarged thyroid gland, elevated levels of thyroxine and triiodothyronine, a depressed thyroid radioactive iodine uptake (RAIU), spontaneous resolution in two to five months, and a focal or diffuse lymphocytic thyroiditis on biopsy. Since 1962, 62 episodes of SRH were found in 56 individuals. Twelve thyroid biopsy specimens showed diffuse or focal lymphocytic thyroiditis. Testing of viral antibodies to a wide range of viruses demonstrated only one patient with notable titer change of 18 tested. Resolution of the hyperthyroidism took two to five months. Four patients were treated inappropriately. Lymphocytic thyroiditis with spontaneously resolving hyperthyroidism appears to be a new syndrome that has dramatically increased in frequency in the past ten years. It is difficult to differentiate from common forms of hyperthyroidism unless RAIU is determined.

Adolescent↗
PubMed1980

Cardiac positron tomography: current status and future directions.

Positron emission tomography (PET) performed after the administration of the positron-emitting radionuclides carbon-11 (11C), nitrogen-13(13N), oxygen-15(15O) and fluorine-18(18F) has permitted the improved noninvasive assessment of the regional myocardial metabolism of normal physiologic substrates and intermediates and their cogeners. In experimental animals, the rate of oxidation of 11C-palmitate correlates closely with other indexes of oxygen consumption, and the extraction of 11 C-palmitate (like that of 18F-fatty acids and 18F-fluordeoxyglucose) is markedly diminished in regions of myocardial ischemia. In both experimental animals and in patients, myocardial infarct site and size, determined by positron emission tomography after the intravenous injection of 11C-palmitate, correlate closely with the electrocardiographic infarct locus and enzymatically estimated infarct size as well as with the location and extent of regional left ventricular wall motion abnormalities. PET offers promise for assessment of flow as well despite the complexities involved. PET with 13NH3 appears to provide one useful qualitative index, although this tracer is actively metabolized. Because of the quantitative capabilities of positron emission tomography and the rapid progress which is being made in the development of fast scan, multi-slice, and gated instrumentation, this technique is likely to facilitate improved understanding and characterization of regional myocardial metabolism and blood flow in man under physiological and pathophysiological conditions.

Animals↗
PubMed1980

Plasma MB creatine kinase activity and other conventional enzymes. Comparison in patients with chest pain and tachyarrhythmias.

We studied 67 patients with tachycardia and chest pain admitted with suspected myocardial infarction; 29 had myocardial infarction (20 transmural, nine subendocardial) with elevated MB creatine kinase (CK) activity, as well as elevated total CK and lactate dehydrogenase (LDH) levels. However, hydroxybutyric dehydrogenase and SGOT activity remained normal in three and four patients, respectively. Despite abnormal ECGs in 84% and typical chest pain in 54%, 38 patients had normal MB CK activity. However, 15 of them had elevated MM CK levels, presumably due to release from skeletal muscle. In total, 29 patients had elevated activity of MM, CK, LDH, or SGOT, but 72% of these patients had cardiac failure, hypotension, or skeletal muscle trauma due to cardioversion. Eleven patients with normal MB CK had elevated hydroxybutyric dehydrogenase activity. Despite elevated activity of other enzymes, MB CK remained normal. Thus, elevated plasma MB CK activity appears to remain a good diagnostic marker of myocardial necrosis in patients with tachyarrhythmias.

Angina Pectoris↗