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Biomedical subjects

M Joyal

Publications and source records attributed to M Joyal.

25 records · Page 2Linked to original sources
PubMed1985

Inability of caliper measurement to enhance observer agreement in the interpretation of coronary cineangiograms.

Important clinical decisions are made on the basis of the interpretation of the degree of stenosis in the coronary cineangiogram. Thus, minimization of observer variation (both intra and inter) is crucial. The purpose of this investigation was to determine if measurement of stenotic lesions by caliper (CM) as compared with the usual eyeball method (EM) would reduce observer variation. Five observers, using the AHA scoring system, estimated maximal luminal narrowing in 14 segments on 10 films providing 2 reports on each film by EM and 2 by CM, thus making observations on 2800 segments. This allowed analysis of intraobserver variation for each reporter for method EM and CM, and for interobserver variation by each method. Since chance agreement is an important component in an observational study, a correction for this was made using the Kappa statistic. The results revealed that the mean Kappa by EM was 0.71 compared to 0.63 by CM (1 being perfect agreement and 0 no agreement). Agreement was much greater in proximal rather than distal segments. Interobserver agreement was consistently higher by EM K = 0.62 than CM K = 0.53 (p = 0.0007). A delineation of the types of disagreement and their clinical significance are important considerations in the evaluation of observer variation. It is concluded that the use of a caliper does not enhance either intra or interobserver agreement.

Cineangiography↗
PubMed1984

Effect of nitroglycerin on coronary collateral flow and pressure during acute coronary occlusion.

Coronary collateral function was evaluated in 21 conscious, unsedated patients by measuring aortic and distal coronary pressures and great cardiac vein flow during transient (1 minute) balloon occlusion of the anterior descending artery in the course of coronary angioplasty. Measurements were made before and during administration of intravenous nitroglycerin (NTG). Clinical, electrocardiographic and hemodynamic events of transient myocardial ischemia occurred in 10 patients before and 6 patients during NTG administration (p = 0.11). The NTG infusion consistently decreased pressure determinants of myocardial oxygen demand without increasing heart rate. NTG also decreased a calculated coronary collateral resistance index in 13 patients. Responsiveness to NTG did not appear to depend on the presence or absence of collateral vessels detected by angiography or on any other angiographic variable assessed. Measurement of coronary collateral function during coronary angioplasty is a new technique with the potential to assess the ability of interventions to prevent transient myocardial ischemia and improve myocardial perfusion during acute coronary occlusion in humans.

Adult↗
PubMed1984

Hemodynamic effects of nitroglycerin combined with diltiazem in patients with coronary artery disease.

Resting coronary and left ventricular hemodynamic effects of diltiazem and nitroglycerin, given intravenously in combination, were studied in 12 patients with coronary heart disease. Results observed with this combination were compared with those in seven patients given diltiazem initially (group I) and five patients given nitroglycerin initially (group II). The diltiazem-nitroglycerin combination reduced systolic blood pressure 27 percent (p less than or equal to 0.05) with no significant change in heart rate to affect a 22 percent (p less than or equal to 0.05) decrease in the rate-pressure product. Left ventricular end-diastolic pressure (-36 percent) and dp/dt (-6.4 percent) both declined (p less than or equal to 0.05). Coronary flow and cardiac output were both maintained. Diltiazem alone and nitroglycerin alone also reduced systolic pressure and the rate-pressure product but to a lesser degree than the combination. Diltiazem did not significantly affect left ventricular end-diastolic pressure and dp/dt. Nitroglycerin reduced left ventricular end-diastolic pressure to an extent similar to the reduction produced by the combination but increased heart rate whereas this determinant of myocardial oxygen demand did not increase significantly with the combination. These findings suggest that the combination of diltiazem and nitroglycerin produces a greater reduction in myocardial oxygen demand than either drug alone. In addition, the combination maintains coronary blood flow without increases in determinants of myocardial oxygen demand. This potentially beneficial drug combination warrants further trial in patients with myocardial ischemia.

Benzazepines↗
PubMed1984

Effects of diltiazem, dipyridamole, and their combination on hemostasis.

Calcium channel blockers and antiplatelet agents, alone and in combination, have been reported to induce bleeding in patients undergoing surgery. Since diltiazem and dipyridamole influence platelet function in vitro and in vivo, their influence on hemostasis was examined in five normal men given diltiazem, 90 mg by mouth, followed by 60 mg every 6 hr for 48 hr, or dipyridamole, 75 mg by mouth every 8 hr for 48 hr. At 24 hr, the alternate drug was added to the regimen to assess effects of the combination on hemostasis. Platelet aggregation, serum thromboxane B2 and 6-keto-PGF1 alpha concentrations (stable metabolites of thromboxane A2 and prostacyclin), bleeding time, prothrombin time, partial thromboplastin time, and serum diltiazem concentrations were measured. Diltiazem and dipyridamole alone and in combination had no significant effect on bleeding time, prothrombin time, or partial thromboplastin time. Platelet aggregation induced by threshold concentrations of adenosine diphosphate, epinephrine, and calcium ionophore A 23187 were inhibited by diltiazem and dipyridamole alone and in combination. The only change in prostaglandin concentrations was a slight increase in serum 6-keto-PGF1 alpha after diltiazem. Despite influences on platelet function, neither diltiazem nor dipyridamole alone or in combination induced clinically relevant changes in hemostasis.

6-Ketoprostaglandin F1 alpha↗
PubMed1984

Usefulness of digital subtraction left ventriculography in patients with ischemic heart disease: comparison with cineangiography.

Digital subtraction and computer enhancement of left ventriculography allow the injection of small amounts of contrast medium into the left ventricle. Image quality measurements of cardiac volumes, and ejection fraction and evaluation of regional wall motion were compared following digital subtraction and cine ventriculography in 30 patients undergoing coronary arteriography for suspected or proven ischemic heart disease. At concentrations of 13% to 19% (iodine contents: 2.0 to 5.0 g) meglumine sodium diatrizoate used for digital subtraction ventriculography, no alterations of ventricular pressures were noted; premature ventricular contraction and cineventriculography in 30 patients undergoing coronary arteriography for suspected wall motion by two independent observers showed complete agreement between digital and cineventriculography in 141 of 150 segments (94%), including 114 normal segments; digital ventriculography led to underestimation of four segments and to overestimation of five. Left ventricular ejection fraction and volumes calculated using both techniques correlated relatively well (ejection fraction: r = 0.86; end systolic volume: r = 0.88; end diastolic volume: r = 0.665). Thus, intraventricular injection of low concentrations of contrast medium provides good digital angiographic images and may eventually replace cine ventriculography for invasive assessment of left ventricular performance. However, ECG gating and shorter exposure times will be required for accurate measurement of ventricular volumes and ejection fractions.

Adult↗
PubMedDate not supplied

Effects of probucol on vascular remodeling after coronary angioplasty. Multivitamins and Protocol Study Group.

BACKGROUND: We have shown that probucol reduces restenosis after balloon angioplasty. Whether probucol acted via prevention of neointimal formation or improvement in vascular remodeling could not be addressed by angiography and required the use of intravascular ultrasound (IVUS). METHODS AND RESULTS: Beginning 30 days before angioplasty, 317 patients were randomly assigned to receive probucol, multivitamins, combined treatment, or placebo. Patients were then treated for 6 months after angioplasty. IVUS examination was performed immediately after angioplasty and at follow-up in 94 patients (111 segments). The cross section selected for serial analysis was the one at the angioplasty site with the smallest lumen area at follow-up. In the placebo group, lumen area decreased by -1. 21+/-1.88 mm2 at follow-up, and wall area and external elastic membrane (EEM) area increased by 1.50+/-2.50 and 0.29+/-2.93 mm2, respectively. Change in lumen area, however, correlated more strongly with the change in EEM area (r=0.53, P=0.002) than with the change in wall area (r=-0.13, P=0.49). Lumen loss was -1.21+/-1.88 mm2 for placebo, -0.83+/-1.22 mm2 for vitamins, -0.25+/-1.17 mm2 for combined treatment, and -0.15+/-1.70 mm2 for probucol alone (P=0.002 for probucol, P=0.84 for vitamins). Change in wall area was similar for all groups. EEM area increased by 0.29+/-2.93 mm2 for placebo, 0. 09+/-2.33 mm2 for vitamins only, 1.17+/-1.61 mm2 for combined treatment, and 1.74+/-1.80 mm2 for probucol only (P=0.005 for probucol). CONCLUSIONS: Lumen loss after balloon angioplasty is due to inadequate vessel remodeling in response to neointimal formation. Probucol exerts its antirestenotic effects by improving vascular remodeling after angioplasty.

Angioplasty, Balloon, Coronary↗