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Biomedical subjects

P Nicod

Publications and source records attributed to P Nicod.

161 records · Page 9Linked to original sources
PubMed1983

A comparison of infarct identification with technetium-99m pyrophosphate and staining with triphenyl tetrazolium chloride.

The topographic relationship between the uptake of technetium-99m pyrophosphate (PPi) and myocardial infarction delineated by 2,3,5-triphenyl tetrazolium chloride (TTC) was studied in a canine model of permanent coronary occlusion (24-48 hr). Photographs of TTC staining and scintigraphic images of PPi uptake were planimetered for infarct area. In addition, narrow tissue samples (3 X 10 mm) were taken on both sides of the TTC border and counted for PPi uptake. A significant correlation (p less than 0.001) was found between area of PPi uptake and area of myocardium unstained by TTC (r = 0.84 in epicardium and r = 0.91 in endocardium). The slope relating PPi to TTC for all infarcts was 1.01 +/- 0.11, indicating that variations in infarct size were followed equally by the two techniques. Tissue counting showed the ratio of PPi activity just inside the infarct to activity just outside the infarct to be 9.2 +/- 0.6 (mean +/- s.e.m.). Thus, PPi is distributed topographically in a manner identical to the distribution of irreversibly injured myocardium as delineated by TTC.

Animals↗
PubMed1982

Increased incidence and clinical correlation of persistently abnormal technetium pyrophosphate myocardial scintigrams following acute myocardial infarction in patients with diabetes mellitus.

"Persistently abnormal" technetium-99m stannous pyrophosphate myocardial scintigrams (PPi+) appear to be associated with a relatively poor prognosis after acute myocardial infarction (AMI). To assess the incidence and implications of PPi+, we performed a retrospective analysis in 29 patients with and 25 patients without diabetes mellitus who had abnormal myocardial scintigrams within 4 days of AMI and who had follow-up scintigrams at least 3 months after hospital discharge. There were no significant differences between patients with and without diabetes as regards age, incidence of transmural or nontransmural AMI, or degree of left ventricular dysfunction after AMI. Persistently abnormal PPi+ occurred more commonly in patients with diabetes than in nondiabetic patients (18 of 29, 62%, compared to 3 of 25, 12%; p less than 0.001). Patients with chronic PPi+ had more frequent cardiac complications following hospital discharge (p less than 0.005) including death, recurrent AMI, unstable angina, and intractable congestive heart failure. Postmortem analysis in two patients with diabetes and chronic PPi+ revealed marked myocytolysis. Thus, patients with diabetes mellitus have an increased incidence of post-AMI "persistently abnormal" technetium (PPi+) scintigrams and relatively poor prognosis following myocardial infarction.

Aged↗
PubMed1982

Effect of increasing heart rate in patients with aortic regurgitation. Effect of incremental atrial pacing on scintigraphic, hemodynamic and thermodilution measurements.

This study was performed to assess the effect of pacing-induced tachycardia in patients with aortic regurgitation. In 12 patients (5 men and 7 women with a mean age of 53 years) with aortic regurgitation, left ventricular end-diastolic and end-systolic volume indexes were measured with multigated equilibrium blood pool imaging, and forward cardiac index was determined with thermodilution, both at rest (mean heart rate +/- standard deviation 72 +/- 8 beats/min) and during atrial pacing at 100 and 120 beats/min. Pacing caused a decremental reduction in left ventricular end-diastolic and end-systolic volume indexes and radionuclide-determined stroke volume index but no change in radionuclide-determined cardiac index or left ventricular ejection fraction. Forward cardiac index increased incrementally from the baseline value at rest to that at 120 beats/min despite a decremental reduction in stroke volume index. There was a stepwise decrease in regurgitant volume/stroke (46 +/- 20 ml/m2 at baseline, 27 +/- 15 at 120 beats/min; p less than 0.05) but no change in regurgitant volume/min (3.38 +/- 1.80 liters/min per m2 at baseline, 3.22 +/- 1.78 at 120 beats/min; difference not significant [NS]) or regurgitant fraction (0.54 +/- 0.13 at baseline, 0.49 +/- 0.13 at 120 beats/min; NS). Mean femoral arterial, pulmonary arterial and pulmonary capillary wedge pressures did not change with pacing.

Aortic Valve Insufficiency↗
PubMed1982

Detection of acute right ventricular infarction by right precordial electrocardiography.

The value of 0.1 mV or greater of S-T segment elevation in at least one right precordial lead (V4R to V6R) in defining right ventricular myocardial infarction was assessed prospectively in 43 subjects (33 consecutive patients with enzymatically confirmed infarction of varying type and location, 4 patients with unstable angina and 6 healthy volunteers). Patients with acute myocardial infarction were studied with radionuclide ventriculography and technetium-99m stannous pyrophosphate myocardial scintigraphy 18.2 +/- 14.3 (mean +/- standard deviation) and 85.1 +/- 18.0 hours after the onset of symptoms, respectively. Eleven patients (Group A: 9 patients with transmural inferior infarction, 1 with transmural inferolateral infarction and 1 with transmural anteroseptal infarction) demonstrated right precordial S-T segment elevation and 22 patients (Group B: 6 patients with transmural inferior infarction, 2 with transmural posterior infarction, 3 with transmural inferolateral infarction, 3 with transmural anteroseptal infarction, 3 with transmural extensive anterior infarction, 4 with subendocardial anterior infarction and 1 with unclassified infarction) did not. Right ventricular ejection fraction was significantly lower in Group A (0.47 +/- 0.11) than in Group B (0.60 +/- 0.12) (p less than 0.01). Right ventricular total wall motion score was 63.8 +/- 15.6 percent of normal in Group A versus 94.3 +/- 8.5 percent in Group B (p less than 0.001). Technetium-99m pyrophosphate uptake (2+ or greater) over the right ventricle occurred in nine patients (81.8 percent) in Group A and in one patient (4.5 percent) in Group B (p less than 0.001). No patient with unstable angina and no healthy volunteer had S-T segment elevation in a right precordial lead. S-T segment elevation of 0.1 mV or greater in one or more of leads V4R to V6R is both highly sensitive (90 percent) and specific (91 percent) in identifying acute right ventricular infarction.

Aged↗
PubMed1982

Clinical implications of anterior S-T segment depression in patients with acute inferior myocardial infarction.

To assess various factors associated with anterior S-T segment depression during acute inferior myocardial infarction, 47 consecutive patients with electrocardiographic evidence of a first transmural inferior infarction were studied prospectively with radionuclide ventriculography an average of 7.3 hours (range 2.9 to 15.3) after the onset of symptoms. Thirty-nine patients (Group I) had anterior S-T depression in the initial electrocardiogram and 8 (Group II) did not have such "reciprocal" changes. There was no difference between the two groups in left ventricular end-diastolic or end-diastolic volume index or left ventricular ejection fraction. Stroke volume index was greater in Group I than in Group II. There were no group differences in left ventricular total or regional wall motion scores. A weak correlation existed between the quantities (mV) or inferior S-T segment elevation and reciprocal S-T depression. No relation between anterior S-T segment depression and the left ventricular end-diastolic volume index could be demonstrated; the extent of left ventricular apical and right ventricular wall motion abnormalities, both frequently associated with inferior infarction, did not correlate with the quantity of anterior S-T depression. These data show that anterior S-T segment depression occurs commonly during the early evolution of transmural inferior infarction, is not generally a marker of functionally significant anterior ischemia and cannot be used to predict left ventricular function in individual patients. Anterior S-T segment depression may be determined by reciprocal mechanisms.

Cardiac Catheterization↗
PubMed1982

Myocardial rupture after myocardial infarction. Detection by multi-gated image-acquisition scintigraphy.

Myocardial rupture following infarction usually is an acute and dramatic event. Rarely, it may take a subacute course, allowing surgical treatment. We report herein a case of subacute rupture of the heart in a 54 year old patient with acute myocardial infarction. The rupture was diagnosed by the appearance of a radiopaque halo around the heart during radionuclide ventriculography. The patient subsequently underwent surgical resection of a large anterolateral aneurysm and a 2 inch long rupture of the myocardium and survived. Clinical suspicion, prompt diagnosis, and surgical intervention are important in the management of this relatively unusual complication of infarction.

Heart Aneurysm↗
PubMed1982

"Doughnut" technetium pyrophosphate myocardial scintigrams. A marker of severe left ventricular dysfunction.

The "doughnut" pattern on Tc-99m pyrophosphate (PPi) myocardial scintigraphy is characterized by a border of tracer uptake surrounding a central zone of relatively decreased activity. This pattern is generally associated with large transmural anterior myocardial infarcts (MI) caused by occlusion or critical stenosis of the left anterior descending coronary artery. Such infarcts typically involve a significant portion of the anterior wall and are associated with a complicated clinical course and poor prognosis. In order to evaluate the relationship between the presence of the doughnut pattern and left ventricular (LV) function, radionuclide ventriculography was performed within 15 days after infarction in 58 patients with transmural anterior MI. In patients without previous MI, 15/38 (39.5%) had doughnut scintigrams. These patients demonstrated significant reductions in LV ejection fraction (EF) (28 +/- 10% versus 45 +/- 12%, P less than 0.001) and normalized LV wall motion scores (29 +/- 11% versus 61 +/- 10%, P less than 0.001) when compared with patients with "nondoughnut" scintigrams. Patients with doughnut scintigrams had a significantly greater incidence of severe septal hypokinesis (P less than 0.001) and apical dyskinesis (P less than 0.03). LV end-systolic volumes were also larger in the patients with doughnut scintigrams (73 +/- 32 ml versus 40 +/- 17 mI/M2, P less than 0.005). In contrast, there was no significant difference in LVEF, normalized LV wall motion score, or LV volumes between doughnut and nondoughnut groups in patients with previous MI.

Diphosphates↗
PubMed1982

Radionuclide techniques for valvular regurgitant index: comparison in patients with normal and depressed ventricular function.

We compared contrast angiography with three techniques of quantitating valvular regurgitation from radionuclide ventriculograms in 70 patients: 45 with documented regurgitation graded 1-4+, and 25 without regurgitation. The radionuclide "regurgitant index" (ratio of L to R ventricular stroke counts) was measured from fixed end-diastolic regions of interest (method A), from separate end-diastolic and end-systolic regions of interest (method B), and from a "stroke-volume image" (method C). Sensitivities for detecting 1+ or more regurgitation were: method A = 57.8%, method B = 37.8% and method C = 62.2%. Sensitivities for detecting 2+ or more regurgitation were: method A = 74.2%, method B = 54.8%, and method C = 77.4%. All methods are greater than 97% specific. Interobserver coefficients of variability were: method A = 9.1%, method B = 19.2%, and method C = 5.4%. The sensitivity of each method was improved when left-ventricular ejection fractions were greater than 0.35. No method consistently differentiated between 2+, 3+, and 4+ valvular regurgitation.

Angiography↗
PubMed1976

Reduced active thyroid hormone levels in acute illness.

In acute and subacute disease the active thyroid hormones, triiodothyronine (T3) and tetraiodothyroacetic acid (tetrac), are decreased while serum-thyroxine (T4) levels tend to be slightly reduced. Conversely, the inactive metabolite, reverse triiodothyronine (reverse T3), is increased indicating a diversion of T4 metabolism from an activating to an inactivating pathway. With convalescence the serum levels of T3, tetrac, and T4 recover while reverse T3 decreases to normal. These changes occur without significant alterations in serum levels of thyroid-stimulating hormone, indicating maintenance of euthyroidism throughout disease.

Acute Disease↗
PubMed1976

Effect of amiodarone on serum triiodothyronine, reverse triiodothyronine, thyroxin, and thyrotropin. A drug influencing peripheral metabolism of thyroid hormones.

2-n-Butyl-3-(4'-diethylaminoethoxy-3',5'-diiodobenzoyl)-benzofurane (amiodarone), a drug used in arrythmias and angina pectoris, contains 75 mg of organic iodine/200 mg active substance. Four studies were performed to test its effect on thyroid hormone metabolism: (a) nine male subjects were treated with 400 mg of amiodarone for 28 days; (b) five male subjects received, for the same period of time, 150 mg of iodine in the form of Lugol's solution; (c) five subjects received 300 mug L-thyroxine (T4) for 16 days; from the 10th to the 16th day, 400 mg of amiodarone was added; and (d) five euthyroid subjects received 300 mug L-T4 for 16 days. The changes in serum thyroid-stimulating hormone (TSH), serum total T4, 3,5,3'-triiodothyronine (T3), free T3, and 3,5',3'-triiodothyronine (reverse T3, rT3) were measured, and the pituitary reserve in TSH was evaluated by a thyrotropin-releasing hormone (TRH) test. The results show that amiodarone induced a decrease in serum T3 (28+/-5.1 ng/100 ml, mean+/-SEM, P less than 0.0S and 82.7+/-9.3 ng rT3/100 ml, P less than 0.01). The control study with an equal amount of inorganic iodine did not induce these opposite changes but slightly lowered serum rT3, T3, and T4. In the third study, serum rT3 increased as under amiodarone treatment, thereby proving that these changes were peripheral. It is suggested that amiodarone changes thyroid hormone metabolism, possibly by reducing deiodination of T4 to T3 and inducing a preferential production of rT3. Amiodarone also increased the response of TSH to TRH. The maximal increment of serum TSH above base line was 32+/-4.5 muU/ml under treatment and 20+/-3 muU/ml before treatment (P less than 0.01). During this test, the serum T3 increase was more pronounced than during the control period (83+/-13 and 47+/-7.4 ng/100 ml, P less than 0.05).

Adult↗
PubMed1976

Radioimmunoassay for 3,3',5'-triiodo-L-thyronine in unextracted serum: method and clinical results.

Serum 3,3',5'-triiodothyronine (rT3) was measured with a radioimmunoassay in unextracted serum. The assay was specific and reproducible. The coefficients of variation for 3 different sera known for high, normal, and low rT3 concentrations between assays were 4, 6, and 9% within assays 4, 9, and 7%, respectively. In euthyroid subjects 20 to 60 years old, rT3 was 450 +/- 200 pg/ml (mean +/- 2 SD.n = 83). Serum rT3 was found to be increased in hyperthyroidism (range: 762-2581 pg-ml; n = 11) but also in acute and chronic illness (up to 2400 pg/ml; n = 24) and in anorexia nervosa (536-1058 pg/ml; n = 7). In the latter two situations there was mostly an inverse change in serum 3,5,3'-triiodothyronine (T3) which was in the low normal range or decreased. These findings suggest a metabolic control of thyroxine deiodination. A low serum rT3 was found in 9 of 12 hypothyroid patients and in the serum of 1 chronically ill patient. Long-term treatment (1-7 years) with lithium carbonate slightly reduced serum rT3, although the changes were inside the normal range. Kidney function was not found to be necessary for its production as anephric patients had normal rT3 values. In addition, hemodialysis increased serum rT3, which is probably due to the heparin therapy.

Adolescent↗
PubMed1976

The failure of physiologic doses of reverse T3 to effect thyroid-pituitary function in man.

Reverse T3 (3,3',5'-triiodothyronine, rT3), a major product of the peripheral monodeiodination of thyroxine (T4), was administered to normal male volunteers in doses sufficient to sustain an elevated serum rT3 concentration similar to that frequently observed in patients with nonthyroidal illness. No changes in basal serum T4, T3, TSH and prolactin concentrations, nor in the T3, TSH and prolactin responses to iv TRH were observed during rT3 administration. These findings suggest that physiologic increases in serum rT3 concentration probably do not inhibit T4 to T3 conversion or the anterior pituitary TSH and prolactin responses to thyrotropin-releasing hormone (TRH).

Adult↗
PubMed1975

Diversion of peripheral thyroxine metabolism from activating to inactivating pathways during complete fasting.

In 9 euthyroid obese volunteers, as previously reported, 4 weeks of total caloric deprivation resulted in a striking decrease in serum 3,5;3'-triiodothyronine (T3) concentration. The present studies reveal that this decrease in serum T3 is accompanied by a proportionately similar increase in the serum concentration of 3,3',5' -T3 (reverse T3; rT3). In four additional obese volunteers given suppressive doses of sodium-Lthyroxine (T4) for 1 month prior to fasting, serum T3 concentration declined sharply during a 6-11 day period of fast, while rT3 concentration increased strikingly. Concentrations of both T3 and rT3 returned to control values during a 5 day period of refeeding. The findings indicate that caloric deprivation results in an alteration in peripheral T4 metabolism away from generation of T3 and toward the generation of rT3. Since the former is more active than T4, and the latter is essentially inactive, caloric deprivation appears to shunt peripheral T4 metabolism from activating to inactivating pathways.

Adult↗