Effect of atrial fibrillation and mitral regurgitation on calculated mitral valve area in mitral stenosis

Forty-nine patients with mitral stenosis (MS) were studied by Doppler echocardiography and 2-dimensional (2-D) echocardiography to assess the ability of Doppler ultrasound to accurately measure mitral valve orifice area and to assess whether atrial fibrillation (AF) or mitral regurgitation (MR) affected the calculation. Twenty-four patients underwent cardiac catheterization. Mitral valve area by Doppler was determined by the pressure half-time method. Mean mitral valve area of all 49 patients by Doppler and 2-D echocardiography correlated well (r = 0.90). There was good correlation between Doppler and 2-D echocardiography in patients with pure MS in sinus rhythm (r = 0.88), in patients with MR (r = 0.93) and in patients with AF (r = 0.96). In the 7 patients with pure MS in sinus rhythm, there was good correlation between Doppler, 2-D echocardiography and cardiac catheterization (r = 0.95). In patients with either MR or AF, cardiac catheterization appeared to underestimate mitral valve orifice compared with both Doppler and 2-D echocardiography (p less than 0.05). Doppler echocardiography can estimate valve area in patients with MS regardless of the presence of MR or AF.

Parathyroid hormone and calcitonin secretion in man: effect of dopamine agonists and antagonists

This study was undertaken to evaluate the physiological role, if any, of dopamine (DA) in modulating parathyroid hormone (PTH) and calcitonin (CT) secretion in man. Infusion of DA (5 micrograms/kg/min) into 6 normal men, decreased serum immunoreactive prolactin (iPRL) and concomitantly increased serum iPTH to 140 +/- 6.8% of baseline (P less than 0.01) at 30 min, with decline thereafter, despite continuation of the DA infusion. Serum iCT levels did not significantly change. Chlorpromazine (50 mg IM), decreased serum iPTH to 75 +/- 5.4% and 79 +/- 3.7% of baseline (P less than 0.01) at 30 and 60 min, respectively, associated with an increase in iPRL. There was subsequent return of iPTH to baseline even though iPRL remained elevated. iCT levels did not significantly change. These observations would suggest that DA may play a physiological role in iPTH, but not iCT, secretion. However, infusion of more nearly physiological doses of DA (0.02, 0.2, and 2.0 micrograms/kg/min) lowered serum iPRL to levels similar to those after the larger DA dose, but with no concomitant increase in either iPTH or iCT. Also, 1) the DA agonist bromocriptine decreased serum iPRL without modifying iPTH or iCT; 2) the DA precursor, levodopa, and the DA antagonist, metoclopramide, had no effect on serum iPTH or iCT levels. These studies suggest that 1) the transient stimulatory effect of DA on iPTH secretion is pharmacological, and 2) DA does not have a physiological role in secretion of iPTH or iCT in man.

A photoaffinity derivative of colchicine: 6'-(4'-azido-2'-nitrophenylamino)hexanoyldeacetylcolchicine. Photolabeling and location of the colchicine-binding site on the alpha-subunit of tubulin

A photoaffinity analog of colchicine, 6-(4'-azido-2'-nitrophenylamino)hexanoyldeacetylcolchicine, was synthesized by reacting deacetylcolchicine or [3H]deacetylcochicine with N-succinimidyl-6-(4'-azido-2'-nitrophenylamino)hexanoate. Homogeneity of the photoaffinity analog was established by thin-layer chromatography and high-pressure liquid chromatography. The structure of the photoaffinity analog was determined by 1H and 13C NMR, infrared and ultraviolet-visible spectroscopies, and elemental analysis. Binding of 6-(4'-azido-2'-nitrophenylamino)hexanoyldeacetylcolchicine to bovine renal tubulin was measured by competition with [3H]colchicine. The value of the apparent Ki for the photoaffinity analog was 0.28 microM in the concentration range of 0.8-1.2 microM of the analog. A value of 0.50 microM for the apparent Kd was measured by the direct binding of the tritiated photoaffinity analog to tubulin. The analog is slightly more potent an inhibitor of microtubule formation than colchicine. The photoaffinity analog reacted with renal tubulin upon irradiation with a mercury lamp equipped with a 420-nm cutoff filter. Spectral and radiochemical analyses of the tubulin after photolysis and dialysis have demonstrated a stoichiometric incorporation of the photoaffinity analog in the alpha-subunit of the tubulin. Covalent labeling of tubulin with the photoaffinity analog decreases the extent of [3H]colchicine binding by more than 90%.

Regulation of myocardial function in health and critical illness

The function of the human heart relies on the complex interplay of preload, afterload, and contractility. Alterations of all three variables occur in disease states. New developments in monitoring allow assessment of cardiac function at the bedside and contribute to patient care.

Doppler hemodynamic evaluation of prosthetic (Starr-Edwards and Björk-Shiley) and bioprosthetic (Hancock and Carpentier-Edwards) cardiac valves

One hundred thirty-four patients with prosthetic or bioprosthetic heart valves were investigated with Doppler echocardiography to determine normal values for commonly used prosthetic valves and to test the specificity of abnormal Doppler findings. In 70 patients the aortic valves had been replaced and in 64 the mitral valves had been replaced. Gradients across prostheses in the aortic position were calculated from maximal velocity. Peak calculated aortic transvalvular gradients in normal subjects were 22 +/- 10 mm Hg in 33 Björk-Shiley valves, 23 +/- 10 mm Hg in 27 porcine valves and 29 +/- 13 mm Hg in 6 Starr-Edwards valves. Mild aortic regurgitation was seen in 42% of Björk-Shiley valves, 26% of porcine valves and 2 of 6 Starr-Edwards valves. Mitral valve orifice was calculated by the pressure half-time method. In clinically normal patients with mitral valve prostheses, the effective mitral valve orifice was 2.5 +/- 0.8 cm2 in 35 Björk-Shiley valves, 2.1 +/- 0.7 cm2 in 17 porcine valves, and 2.0 +/- 0.3 cm2 in 10 Starr-Edwards valves. Mitral regurgitation was found in 11% of Björk-Shiley valves, 19% of porcine valves and 30% of Starr-Edwards valves. Repeat studies at 2 weeks to 14 months revealed no difference in 8 aortic and 14 mitral prostheses. Seven aortic and 4 mitral valves functioned abnormally as determined by Doppler, and the abnormal function was confirmed in each at surgery or at cardiac catheterization.(ABSTRACT TRUNCATED AT 250 WORDS)

Noninvasive assessment of pacemaker hemodynamics by Doppler echocardiography: importance of left atrial size

The relative decrease in cardiac output with ventricular pacing versus "physiologic" modes was measured noninvasively using Doppler echocardiography in 26 patients. Standard echocardiographic measurements of left ventricular size (diastolic diameter), left ventricular function (shortening fraction) and left atrial size were examined to determine which of these variables might best identify patients more likely to benefit from maintenance of atrioventricular (AV) synchrony. Decreases in relative cardiac output, expressed as reduction in the Doppler-derived flow velocity integral, with loss of AV synchrony ranged from 0 to 43% (mean decrease 21%). There was no correlation between left ventricular size or function and effect of pacing mode on relative cardiac output. There was, however, correlation between left atrial size and sensitivity to pacing mode. Patients with normal left atrial size were significantly more sensitive to loss of AV synchrony. In this subgroup, the decrease in flow velocity integral with ventricular pacing was 32 +/- 11% compared with only 11 +/- 13% in patients with left atrial enlargement. Thus, Doppler echocardiography is useful in assessing optimal pacing mode in the individual patient. Echocardiographically measured left atrial size may identify patients in whom physiologic pacing may be major benefit.

Effect of the parasympathetic system on secretion of parathyroid hormone

This study evaluated the effect of parasympathetic agonists and antagonists on immunoreactive (i) PTH secretion in vitro and on serum iPTH in vivo in rats. In in vitro studies pilocarpine or bethanechol significantly inhibited PTH secretion. This inhibition was blocked by the simultaneous addition of atropine to the incubation medium. In in vivo studies, the cholinergic agonists pilocarpine and bethanechol and the cholinergic antagonist atropine were administered to rats by IV infusion. Blood was obtained before and again after two hours of infusion for analysis of iPTH. Pilocarpine or bethanechol significantly decreased serum iPTH. This inhibition by either agent was blocked by the simultaneous administration of atropine. Administration of atropine alone significantly increased serum iPTH above baseline. This stimulation of basal serum iPTH by parasympathetic blockade suggests that even basal PTH secretion may be influenced by endogenous parasympathetic tone. Therefore, the following conclusions were reached: (1) parasympathetic influences inhibit PTH secretion, and (2) endogenous parasympathetic tone may be an inhibitory modulator of basal secretion of PTH.

Heart graft arteriosclerosis. An ominous finding on endomyocardial biopsy

Heart graft arteriosclerosis remains a severe and irreversible complication of allogeneic heart transplantation despite prophylactic therapy. Immunologically mediated endothelial damage has been proposed as a stimulus for the development of graft arteriosclerosis. The vascular lesions may accumulate large amounts of lipid resembling atheromas, or may be purely proliferative, as illustrated in the case of a 42-year-old heart transplant patient who developed slowly progressive graft dysfunction at eight months posttransplantation. Endomyocardial biopsy ten months posttransplantation revealed proliferative arteriolar occlusion, while changes on the coronary angiogram were minimal. Repeat biopsy at eleven months showed ischemic myocardial necrosis. The patient expired shortly thereafter. On postmortem examination, proliferative graft arteriosclerosis affecting both intramural and epicardial vessels was present, along with massive biventricular infarction. Tissue immunofluorescence studies demonstrated extensive vascular deposition of immunoglobulin and complement. We propose that (1) the presence of proliferative arteriolar occlusion on endomyocardial biopsy is predictive of poor heart graft survival; (2) proliferative graft arteriosclerosis may appear as advanced small vessel disease before extensive large vessel involvement is detected by coronary angiogram; and (3) immunofluorescence results support an immune-mediated mechanism of vascular injury in proliferative heart graft arteriosclerosis.

Clinical experience with two-dimensional echocardiography to guide endomyocardial biopsy

Two-dimensional echocardiography was used to aid right ventricular endomyocardial biopsy during 163 procedures in 83 patients being evaluated for myocarditis, cardiac transplant rejection, or drug toxicity. Thirty procedures were performed using combined echocardiography and fluoroscopy and 133 using echocardiography alone. For 80 of the 83 patients (96%) the forceps could be adequately visualized entering the right atrium, crossing the tricuspid valve, and advancing to the right ventricular apex and free wall. The catheter could be guided to biopsy the septum and sample multiple, separate sites along the right ventricular walls. By opening the forceps prior to contact with the myocardium, the right ventricular free wall could be biopsied without perforation. We found two-dimensional echocardiography to be a useful and safe technique for forceps visualization and manipulation in the right ventricle.

The effects of sampling site on the two-dimensional echo-Doppler determination of cardiac output

Cardiac output was measured by two-dimensional echocardiographic Doppler technique in 55 adult patients in the intensive care unit. Doppler cardiac output determinations were measured from four sites (suprasternal long axis of the ascending aorta, suprasternal long axis of the descending aortic, apical left ventricular outflow tract, and parasternal long axis of the main pulmonary artery) and were compared to cardiac output determined by thermodilution for a total of 101 observations (r = 0.84). Mean cardiac output was 5.3 L/min (range 1.8 to 9.5 L/min) by Doppler technique and 5.1 L/min (range 1.6 to 8.9 L/min) as measured by thermodilution. Correlation of Doppler cardiac output with thermodilution cardiac output gave r values of 0.85, 0.83, 0.90, and 0.81 from the ascending aorta, descending aorta, left ventricular outflow tract, and pulmonary artery, respectively. Averaging of data in patients in whom more than one determination was possible resulted in improved correlation (r = 0.94). Thus, cardiac output can be measured with reasonable accuracy by Doppler from a variety of sampling sites and averaging of data from more than one site may improve these results.

Value of multiple echocardiographic views in the evaluation of aortic stenosis in adults by continuous-wave Doppler

Fifty-two adults referred for evaluation of aortic stenosis (AS) were studied using continuous-wave and pulsed Doppler echocardiography. Three windows were used to determine which approach (apical, right parasternal or suprasternal) yielded optimal results. Doppler-derived peak aortic valve gradients were compared with the peak gradients measured at cardiac catheterization in 23 patients. High-velocity jets were best recorded from the cardiac apex and less frequently from the right parasternal and suprasternal areas. However, gradients from the right parasternal area correlated best with cardiac catheterization findings, although recordings could be made from this window in only 49% of the patients. Velocities from the suprasternal window were significantly (p less than 0.01) lower than those from the apex or right parasternal areas. Gradient underestimation from the suprasternal window tended to increase with age of the patient (p less than 0.01). When the maximal Doppler derived gradient from any window was compared with catheterization measurements, the correlation coefficient was 0.86. Gradients derived from Doppler velocities accurately predicted severe (more than 50 mm Hg) gradients at catheterization. Thus, Doppler echocardiography is useful in evaluation of AS when several windows are used for optimal assessment of aortic valve gradient.

Structural studies of Technetium Complexes. VIII. The Crystal Structure of Tetraphenylarsonium Tetrabromonitridotechnetate(VI)

The crystal structure of [AsPh4] [TcNBr4] has been determined by single- crystal X-ray diffraction methods at 20�1°C. Crystals are tetragonal, space group P4/n, with a 12.875(2), c 7.992(1)Ǻ, and Z 2. Full-matrix least-squares refinement gave a final R value of 0.039 for 1263 independent reflections. The compound is isostructural with the series [AsPh4] [MNBr4] (M = Mo, Ru , Re or Os) and [AsPh4] [MNCl4](M = Mo, Tc , Ru, Re or Os), and with [AsPh4] [OsNI4] and [AsPh4]- [MOCl4](M = Mo or Re). The [TcNBr4]- anion in [AsPh4] [TcNBr4] possesses C4v symmetry with Br- Tc -Br bond angles of 87.08(1) and 153.91(4)°, and N= Tc -Br bond angles of 103.04(2)°. The Tc≡N bond distance is 1.596(6)Ǻ, and the Tc - Br distances are 2.4816(5)Ǻ.

Frequency of mitral valve dysfunction from mitral anular calcium as detected by Doppler echocardiography

Doppler echocardiography is useful for detecting and quantifying mitral regurgitation (MR) and mitral stenosis (MS). To determine the prevalence of these abnormalities in patients with mitral anular calcium (MAC), 51 consecutive patients who had an echocardiographic diagnosis of MAC were examined by Doppler ultrasound. Transmitral flow was evaluated to determine the presence of MR or left ventricular inflow obstruction (MS) by continuous and pulsed-wave Doppler echocardiography. The severity of these hemodynamic abnormalities was quantitated by previously described techniques. Eleven patients (22%) had mild MR, 17 (33%) had moderate to severe MR and 4 (8%) had significant MS. Clinical findings such as a systolic murmur, evidence of congestive heart failure, and dyspnea on exertion were not helpful in distinguishing patients with no or mild MR from those who had moderate to severe MR. M-mode measured left atrial size was significantly larger (p less than 0.05) in patients with moderate to severe MR. This study suggests that MR is often associated with MAC, that MS is not a rare finding with MAC, and that Doppler echocardiography can quantitate these lesions in the elderly when symptoms are not specific and physical findings are inconclusive or absent.

Structural Studies on Catalysts and Catalyst Precursors. II. The X-Ray Structure Determination of Chloro(Pentante-2,4-dithionato)(tributylphosphine)nickel(II), Ni(sacsac)(PBu3)Cl

The preparation and characterization of Ni( sacsac )(PBu3) Cl by single crystal X-ray diffraction [refined to R 0.052, R? 0.042 with 1325 data having I ≥ 3σ(I)], are reported. The compound crystallizes as discrete molecules in the orthorhombic space group P bca, with a 15.526(4), b 15.774(4), c 18.377(8)Ǻ, U 4500.7 Ǻ3, and Z 8. The nickel-donor atom bond distances are Ni-S (trans Cl ) 2.097(3), Ni-S (trans P) 2.138(3), Ni- Cl 2.216(3) and Ni-P 2.237(3)Ǻ, with the ligands subtending angles S-Ni-S 98.6(1), S-Ni- Cl 85.4(1), S-Ni-P 89.5(1) and Cl -Ni-P 86.8(1). The coordination about the nickel(II) centre is planar; however, one butyl group of the phosphine is oriented so that a hydrogen is directed towards the apical position of the nickel. The structure is correlated with the N.M.R . spectra in both solid and solution phases and compared with the structures of related com- pounds. The Ni-S bonds are shown to be short and the Ni-P bond long relative to such dimensions in comparable compounds.

Electrophoresis of proteins and nucleic acids on acrylamide-agarose gels lacking covalent crosslinking

The preparation of acrylamide-agarose gels lacking covalent crosslinking with methylenebisacrylamide is described. These hybrid gels melt at 85 degrees C and, consequently, allow quantitative analysis of tritium-labeled protein after electrophoresis. Recovery of tritium-labeled ribonucleic acids extracted from hybrid gels is 20 to 25% greater than from standard acrylamide-methylenebisacrylamide gels. Standard curves of electrophoretic mobilities as a function of molecular weights of dissociated proteins and ribonucleic acids are compared for acrylamide-agarose gels and acrylamide-methylenebisacrylamide gels.

Clearance from the anterior chamber of RBCs from human diabetics

Erythrocytes from diabetic patients manifest decreased deformability and increased adherence. These abnormal membrane properties may diminish the ability of erythrocytes (RBCs) from diabetics to undergo deformation in passage through the trabecular meshwork. Using sodium chromate Cr 51-labeled RBCs from type I diabetic patients with proliferative retinopathy and normal control subjects, we studied RBC clearance from the rabbit anterior chamber. The mean time for 50% clearance (T50) of RBCs from diabetics (76 hours) was significantly longer than that for RBCs from normal subjects (19.5 hours). In this model, RBCs from diabetics have a slower clearance from the anterior chamber than do RBCs from normal subjects.