Aortic valve endothelial cells undergo transforming growth factor-beta-mediated and non-transforming growth factor-beta-mediated transdifferentiation in vitro.

Cardiac valves arise from endocardial cushions, specialized regions of the developing heart that are formed by an endothelial-to-mesenchymal cell transdifferentiation. Whether and to what extent this transdifferentiation is retained in mature heart valves is unknown. Herein we show that endothelial cells from mature valves can transdifferentiate to a mesenchymal phenotype. Using induction of alpha-smooth muscle actin (alpha-SMA), an established marker for this process, two distinct pathways of transdifferentiation were identified in clonally derived endothelial cell populations isolated from ovine aortic valve leaflets. alpha-SMA expression was induced by culturing clonal endothelial cells in medium containing either transforming growth factor-beta or low levels of serum and no basic fibroblast growth factor. Cells induced to express alpha-SMA exhibited markedly increased migration in response to platelet-derived growth factor-BB, consistent with a mesenchymal phenotype. A population of the differentiated cells co-expressed CD31, an endothelial marker, along with alpha-SMA, as seen by double-label immunofluorescence. Similarly, this co-expression of endothelial markers and alpha-SMA was detected in a subpopulation of cells in frozen sections of aortic valves, suggesting the transdifferentiation may occur in vivo. Hence, the clonal populations of valvular endothelial cells described here provide a powerful in vitro model for dissecting molecular events that regulate valvular endothelium.

Synchronized independent lung ventilation in palliated congenital heart disease with variable sources of pulmonary blood flow.

OBJECTIVE: Presentation of two patient studies demonstrating the use of synchronized independent lung ventilation in the management of acute respiratory failure in patients with complex palliated congenital heart disease and variable sources of pulmonary blood flow. DESIGN: Clinical course of two patients. SETTING: Cardiac intensive care unit in a tertiary care, university-affiliated pediatric teaching hospital. PATIENTS: Patient 1 was a 22-yr-old woman with a single ventricle and right lung blood flow supplied by a classic Glenn shunt and left lung blood flow through a systemic-to-pulmonary artery shunt. Patient 2 was a 12-yr-old boy with tetralogy of Fallot and complete common atrioventricular canal defect with right lung blood flow supplied by a classic Glenn shunt and left lung blood flow supplied by the right ventricle. Both patients presented with acute, left-sided lung disease and hypoxemia. INTERVENTIONS: We used selective bronchial intubation via a double-lumen tracheal tube with a bronchial extension for synchronized independent lung ventilation to permit high-pressure ventilation of the abnormal left lung low-pressure ventilation of the normal right lung supplied by a Glenn shunt. Inhaled nitric oxide was administered to both patients and continued in one when improved oxygenation was observed. MEASUREMENTS AND MAIN RESULTS: Serial arterial blood gas measurements, mechanical indices of pulmonary function, and chest radiographs were closely followed. Synchronized independent lung ventilation contributed to improvements in systemic arterial blood oxygenation and alveolar ventilation allowing resumption of conventional ventilation in both patients. No adverse effects related to bronchial tube placement or maintenance occurred. CONCLUSION: Independent lung ventilation is an effective means of isolating the two lungs for differential ventilation, as well as the selective delivery of inhaled medications. In patients with unilateral lung disease and a Glenn shunt supplying the unaffected lung, selective lung ventilation allows aggressive treatment of the abnormal lung while optimizing flow through the Glenn shunt to maximize effective pulmonary blood flow, systemic oxygenation, and hemodynamics.

Effects of a monoclonal antibody to P-selectin on recovery of neonatal lamb hearts after cold cardioplegic ischemia.

BACKGROUND: The interaction between endothelium and leukocytes plays a crucial role in ischemia-reperfusion injury. P-selectin, which is expressed on activated endothelium, mediates the first step in leukocyte adherence to the endothelium. This study examined the effects of a monoclonal antibody (mAb) against P-selectin on the recovery of cardiac function and myocardial neutrophil infiltration after ischemia. METHODS AND RESULTS: Thirteen blood-perfused, isolated neonatal lamb hearts underwent 2 hours of hypothermic cardioplegic arrest and 2 hours of reperfusion. Immediately before reperfusion, mAb to P-selectin was administered to the perfusate (15 micrograms/mL) in 6 hearts (group P-sel). In control (n = 7), the same volume of saline was added. Isovolumic left ventricular function and coronary blood flow were measured. At 2 hours after reperfusion, myocardial myeloperoxidase activity, an index of neutrophil accumulation, was assayed. At 30 minutes of reperfusion, hearts treated with mAb to P-selectin achieved significantly greater recovery of maximum developed pressure (70 +/- 4% in control versus 77 +/- 2% in group P-sel, P < 0.01), maximum positive first derivative of pressure (dP/dt) (64 +/- 7% in control versus 73 +/- 5% in group P-sel, P < 0.05), and maximum negative dP/dt (61 +/- 6% in control versus 70 +/- 6% in group P-sel, P < 0.05) compared with control. Percent baseline of coronary blood flow was also significantly increased in group P-sel (135 +/- 40% in control versus 205 +/- 43% in group P-sel, P < 0.05). Myocardial myeloperoxidase activity was significantly lower (P < 0.05) in group P-sel (4.7 +/- 3.2) versus control (16.0 +/- 10.1). (Units are change in absorbance/min/g tissue.) CONCLUSIONS: The functional blockade of P-selectin resulted in better recovery of cardiac function and attenuated neutrophil accumulation during early reperfusion. Strategies to block P-selectin mediated neutrophil adherence may have clinical application in improving myocardial function at early reperfusion.

Transendothelial chemotaxis of human alpha/beta and gamma/delta T lymphocytes to chemokines.

Two subpopulations of human T lymphocytes expressing different antigen receptors, alpha/beta and gamma/delta, emigrate into inflamed tissues in distinctive patterns. We compared the transmigration of alpha/beta and gamma/delta T cells to C-C and C-X-C chemokines using an in vitro transendothelial chemotaxis assay. The C-C chemokines monocyte chemoattractant protein (MCP)-1, RANTES, macrophage inflammatory protein (MIP)-1alpha and MIP-1beta stimulated similar, dose-dependent chemotaxis of purified gamma/delta T cells, whereas MCP-1, RANTES, and MIP-1alpha produced greater chemotaxis of purified alpha/beta T cells than MIP-1beta. In contrast, the C-X-C chemokines interleukin (IL)-8 and interferon-gamma inducible protein-10 (IP-10) did not promote chemotaxis of either alpha/beta or gamma/delta T cells. Three gamma/delta T cell clones with differing CD4 and CD8 phenotypes also migrated exclusively to C-C chemokines. Phenotypic analysis of mononuclear cells that transmigrated from an input population of unfractionated peripheral blood mononuclear cells confirmed the results with purified gamma/delta T cells. Our data demonstrate that human peripheral blood alpha/beta and gamma/delta T cells can transmigrate to MCP-1, RANTES, MIP-1alpha, and MIP-1beta, and suggest that both T lymphocyte subpopulations share the capacity to emigrate in response to C-C chemokines during inflammation.

Contrasting responses to multiple chemotactic stimuli in transendothelial migration: heterologous desensitization in neutrophils and augmentation of migration in eosinophils.

At inflammatory sites in vivo, leukocytes may confront multiple, competing chemoattractive signals. We found significant differences between eosinophils and neutrophils in transendothelial chemotaxis to a chemoattractant diffusing from the lower chamber, when a chemoattractant that binds to another receptor is present at uniform concentration. The transendothelial migration of eosinophils to FMLP, C5a, RANTES, or MCP-3 was totally inhibited by the presence of the homologous chemoattractant, and only RANTES and MCP-3 showed mutual inhibition. C5a and to a lesser extent FMLP chemokinetically stimulated migration to RANTES and MCP-3, without stimulating random migration. Results with neutrophils contrasted. The presence of FMLP not only abrogated neutrophil transmigration to FMLP but also strongly decreased chemotaxis to C5a, IL-8, and Gro-alpha. Similarly, C5a inhibited neutrophil chemotaxis to IL-8 and Gro-alpha. IL-8 almost totally abrogated chemotaxis to Gro-alpha, but Gro-alpha only moderately inhibited chemotaxis to IL-8. Neither IL-8 nor Gro-alpha significantly inhibited transmigration to FMLP or C5a. Actin polymerization in eosinophils and neutrophils was desensitized by the same combinations of chemoattractants that desensitized chemotaxis. We conclude that eosinophils have at least three noninterfering receptor-signal transduction pathways for chemotaxis and actin polymerization. In contrast, the signaling pathways for FMLP, C5a, and IL-8/Gro-alpha in neutrophils are heterologously cross-desensitized, with a hierarchy of resistance to competing signals of FMLP > C5a > IL-8 > Gro-alpha, in agreement with previous results in neutrophils on the Ca2+-mobilizing response. These results may have important implications for the behavior of these cell types in inflammatory sites.

Perioperative effects of alpha-stat versus pH-stat strategies for deep hypothermic cardiopulmonary bypass in infants.

OBJECTIVES: In a randomized, single-center trial, we compared perioperative outcomes in infants undergoing cardiac operations after use of the alpha-stat versus pH-stat strategy during deep hypothermic cardiopulmonary bypass. METHODS: Admission criteria included reparative cardiac surgery, age less than 9 months, birth weight 2.25 kg or more, and absence of associated congenital or acquired extracardiac disorders. RESULTS: Among the 182 infants in the study, diagnoses included D-transposition of the great arteries (n = 92), tetralogy of Fallot (n = 50), tetralogy of Fallot with pulmonary atresia (n = 6), ventricular septal defect (n = 20), truncus arteriosus (n = 8), complete atrioventricular canal (n = 4), and total anomalous pulmonary venous return (n = 2). Ninety patients were assigned to alpha-stat and 92 to pH-stat strategy. Early death occurred in four infants (2%), all in the alpha-stat group (p = 0.058). Postoperative electroencephalographic seizures occurred in five of 57 patients (9%) assigned to alpha-stat and one of 59 patients (2%) assigned to pH-stat strategy (p = 0.11). Clinical seizures occurred in four infants in the alpha-stat group (4%) and two infants in the pH-stat group (2%) (p = 0.44). First electroencephalographic activity returned sooner among infants randomized to pH-stat strategy (p = 0.03). Within the homogeneous D-transposition subgroup, those assigned to pH-stat tended to have a higher cardiac index despite a lower requirement for inotropic agents; less frequent postoperative acidosis (p = 0.02) and hypotension (p = 0.05); and shorter duration of mechanical ventilation (p = 0.01) and intensive care unit stay (p = 0.01). CONCLUSIONS: Use of the pH-stat strategy in infants undergoing deep hypothermic cardiopulmonary bypass was associated with lower postoperative morbidity, shorter recovery time to first electroencephalographic activity, and, in patients with D-transposition, shorter duration of intubation and intensive care unit stay. These data challenge the notion that alpha-stat management is a superior strategy for organ protection during reparative operations in infants using deep hypothermic cardiopulmonary bypass.

Neutrophil rolling, arrest, and transmigration across activated, surface-adherent platelets via sequential action of P-selectin and the beta 2-integrin CD11b/CD18.

Platelets bound to thrombogenic surfaces have been shown to support activation-dependent firm adhesion of neutrophils in flow following selectin-mediated tethering and rolling. The specific receptor(s) responsible for mediating adhesion-strengthening interactions between neutrophils and platelets has not previously been identified. Furthermore, the ability of adherent platelets to support the migration of bound neutrophils has not been tested. We studied neutrophil interactions with activated, surface-adherent platelets as a model for leukocyte binding in vascular shear flow and emigration at thrombogenic sites. Our results demonstrate that the beta 2-integrin Mac-1 (CD11b/CD18) is required for both firm attachment to and transmigration of neutrophils across surface-adherent platelets. In flow assays, neutrophils from patients with leukocyte adhesion deficiency-1 (LAD-I), which lack beta 2-integrin receptors, formed P-selectin-mediated rolling interactions, but were unable to develop firm adhesion to activated platelets, in contrast to healthy neutrophils, which developed firm adhesion within 5 to 30 seconds after initiation of rolling. Furthermore, the adhesion-strengthening interaction observed for healthy neutrophils could be specifically inhibited by monoclonal antibodies (mAbs) to Mac-1, but not to lymphocyte function-associated antigen-1 (LFA-1; CD11a/CD18) or intercellular adhesion molecule-2 (ICAM-2; CD102). Further evidence for a beta 2-integrin-dependent neutrophil/platelet interaction is demonstrated by the complete inhibition of interleukin (IL)-8-induced neutrophil transmigration across platelets bound to fibronectin-coated polycarbonate filters by mAbs to Mac-1. Thus, Mac-1 is required for firm adhesion of neutrophils to activated, adherent platelets and may play an important role in promoting neutrophil accumulation on and migration across platelets deposited at sites of vascular injury.

Interactions of human alpha/beta and gamma/delta T lymphocyte subsets in shear flow with E-selectin and P-selectin.

We have compared the ability of human alpha/beta and gamma/delta T lymphocytes to adhere to selectin-bearing substrates, an interaction thought to be essential for homing and localization at sites of inflammation. Both T cell populations form rolling adhesions on E- and P-selectin substrates under physiologic flow conditions. Although equivalent to alpha/beta T cells in binding to E-selectin, gamma/delta T cells demonstrated greater ability to adhere to P-selectin that was purified or expressed on the surface of activated, adherent platelets. Under static conditions, 80% of gamma/delta T cells and 53% of alpha/beta T cells formed shear-resistant adhesions to P-selectin, whereas only 30% of gamma/delta and alpha/beta T cells adhered to E-selectin. The enhance ability of gamma/delta T cells to adhere to P-selectin cannot be attributed to differences in expression of the P-selectin glycoprotein ligand (PSGL-1), as all alpha/beta T cells versus approximately 75% of gamma/delta T cells expressed PSGL-1. Both cell populations expressed a similar percentage of the carbohydrate antigens sialyl LewisX and cutaneous lymphocyte-associated antigen. Depletion of lymphocyte populations or T cell clones bearing these oligosaccharides with the monoclonal antibody CSLEX-1 and HECA-452, respectively, resulted in a substantial reduction in adhesion to E-selectin and slight reduction in adhesion to P-selectin under flow conditions. Treatment of cells with an endopeptidase that selectively degrades O-sialomucins such as PSGL-1, abolished P-selectin but not E-selectin adhesion. Removal of terminal sialic acids with neuraminidase or protease treatment of cells abrogated cell adhesion to both selectin substrates. These results provide direct evidence for the presence of distinct E- and P-selectin ligands on T lymphocytes and suggest that gamma/delta T cells may be preferentially recruited to inflammatory sites during the early stages of an immune response when P-selectin is upregulated.

Effects of endothelin-1 and L-arginine after cold ischemia in lamb hearts.

BACKGROUND: Prior studies from our laboratory have suggested an important role for the coronary endothelium in the injury resulting from hypothermic ischemia and reperfusion. A decreased endothelial response to intraarterial acetylcholine occurs after ischemia/reperfusion, implying a reduced release of the vasodilator nitric oxide by endothelial cells, but the role of endothelial-derived vasoconstrictor endothelin-1 in ischemia/reperfusion and interactions between endothelin-1 and nitric oxide in ischemia/reperfusion are still unclear. METHODS: We examined the effects of endothelin-1 and L-arginine, the precursor for nitric oxide, on functional recovery of isolated, blood-perfused neonatal lamb hearts undergoing 2 hours of ischemia at 10 degrees C. One group (n = 8) received 10 pmol/L endothelin-1 before reperfusion, and a second group (n = 8) received a continuous infusion of 3 mmol/L L-arginine during the initial 20 minutes of reperfusion. The third group (n = 8) received both endothelin-1 and L-arginine in the same way as in the endothelin-1 and L-arginine groups. The fourth group underwent the same period of hypothermic ischemia without interventions during reperfusion. RESULTS: After 30 minutes of reperfusion, the endothelin-1-treated hearts showed significantly reduced recovery of left ventricular systolic function (positive maximum dP/dt and volume normalized [V10] dP/dt) and diastolic function (negative maximum dP/dt), coronary blood flow, and myocardial oxygen consumption compared with the control group (p < 0.05). These effects of endothelin-1 were offset to equal the values observed in controls having unmodified reperfusion by adding L-arginine. The L-arginine group had significantly greater recovery of left ventricular systolic function (positive maximum dP/dt, maximum developed pressure, dP/dt at V10, and developed pressure at V10) and diastolic function (negative maximum dP/dt), coronary blood flow, and myocardial oxygen consumption compared with the control group (p < 0.05). CONCLUSION: These results, combined with our previous observations that endothelin-1 levels are unchanged by hypothermic ischemia and reperfusion, suggest that there is an imbalance between the endothelial production of endothelin-1 and nitric oxide, which affects postischemic coronary blood flow and the recovery of ventricular function. Interventions that modify this imbalance of endothelially derived substances could favorably influence the outcome after a period of hypothermic ischemia and reperfusion.

C-C chemokines, but not the C-X-C chemokines interleukin-8 and interferon-gamma inducible protein-10, stimulate transendothelial chemotaxis of T lymphocytes.

Eight chemokines were tested for ability to elicit transendothelial chemotaxis of unstimulated peripheral blood T lymphocytes. The C-C chemokines monocyte chemotactic protein (MCP)-2, MCP-3, RANTES, macrophage inflammatory protein (MIP)-1 alpha, MIP-1 beta, and, as previously described, MCP-1 induced significant, dose-dependent transendothelial chemotaxis of CD3+ T lymphocytes. In contrast, the C-X-C chemokines interleukin-8 (IL-8) and interferon-gamma inducible protein-10 (IP-10) failed to induce transendothelial chemotaxis of CD3+ T lymphocytes or T lymphocyte subsets. RANTES, MIP-1 alpha, and MIP-1 beta induced significant transendothelial chemotaxis of CD4+, CD8+, and CD45R0+ T lymphocyte subsets. Phenotyping of mononuclear cells that underwent transendothelial migration to MCP-2, MCP-3, RANTES, or MIP-1 alpha showed both monocytes and activated (CD26 high), memory-type (CD45R0+) T cells. Both CD4+ and CD8+ T lymphocytes were recruited, but not natural killer cells or significant numbers of B cells. MCP-2 was the only C-C chemokine tested that attracted a significant number of naive-type (CD45RA+) T lymphocytes. In the absence of endothelium, IL-8 but not IP-10 promoted modest but significant chemotoxis of CD3+ T lymphocytes. Our data support the hypothesis that C-C, not the C-X-C chemokines IL-8 or IP-10, promote transendothelial chemotaxis of T lymphocytes.

Characterization of transendothelial chemotaxis of T lymphocytes.

We have adapted a chemotaxis assay using human umbilical vein endothelial cell (HUVEC) monolayers on microporous membranes for studying lymphocyte transendothelial chemotaxis in vitro. Supernatants of peripheral blood mononuclear cells stimulated with phytohemagglutinin (PHA) were identified as an excellent source of lymphocyte chemoattractant activity. The activity in PHA supernatant typically caused 2-6% of peripheral blood lymphocytes (PBL) to transmigrate compared to 0.1-0.3% to media control. Checkerboard analysis demonstrated that transmigration was directional and not attributable to random locomotion. Purified T lymphocytes also underwent transendothelial chemotaxis to PHA supernatant. Using monoclonal antibodies to several human adhesion receptors, we found that the interaction between LFA-1 and ICAM-1/ICAM-2 was more important for transendothelial lymphocyte chemotaxis than the interaction between VLA-4 and VCAM-1. A monoclonal antibody to the beta 1 integrin subunit inhibited chemotaxis more than antibodies to the VLA alpha 2, alpha 3, alpha 4, or alpha 5 subunits. The transendothelial assay was used to guide purification of the lymphocyte chemoattractant activity, which we reported previously to be monocyte chemoattractant protein-1 (MCP-1) (Carr et al., Proc. Natl. Acad. Sci. USA (1994) 91, 3652). The adhesion molecules required for chemotaxis to MCP-1 were similar to those with PHA supernatant. The use of HUVEC in the assay enhances the signal-to-background ratio of chemotaxis and provides a model that is physiologically relevant to lymphocyte emigration from the bloodstream into sites of inflammation.

Ten-year institutional experience with palliative surgery for hypoplastic left heart syndrome. Risk factors related to stage I mortality.

BACKGROUND: We reviewed 212 consecutive patients who underwent stage I palliative surgery for hypoplastic left heart syndrome (HLHS) at our institution between January 1983 and June 1993. METHODS AND RESULTS: Six surgeons participated in the care of these patients. Follow-up is 97% complete. Preoperative anatomic and physiological factors and procedural features of the stage I operation were analyzed for impact on stage I mortality, survival to stage II palliation, and actuarial survival. Hospital mortality was not significantly lower during the second half of the study period (P = .242). Operative mortality was 46.2%. Multivariate analysis revealed improved stage I operative survival in patients with mitral stenosis (MS) and aortic stenosis (AS; P = .006). Additional risk factors for stage I mortality were a lower immediately pre-stage I pH (P = .034) and weight < 3 kg (P = .015). Overall first-year actuarial survival for MS/AS was 59%, and it was 33% for all others (P = .001). Among stage I survivors, patients with MS/AS were more likely to survive to stage II palliation (P = .031). Analysis of actuarial survival of stage I survivors showed that a smaller ascending aorta (P < .001), aortic atresia (P < .001), and mitral atresia (P = .002) were all risk factors for intermediate death. CONCLUSIONS: Preoperative anatomic and physiological state are predictors of stage I mortality. HLHS anatomic subtype also influences intermediate outcome, most notably pre-stage II attrition. These data may be useful in choosing initial management for patients with HLHS.

Effects of endothelin-1 and endothelin-A receptor antagonist on recovery after hypothermic cardioplegic ischemia in neonatal lamb hearts.

BACKGROUND: Prior studies suggest an important role for coronary endothelium in ischemia/reperfusion (I/R) injury. Decreased endothelial release of the vasodilator nitric oxide occurs after I/R, but the role of the endothelium-derived vasoconstrictor endothelin-1 (ET-1) in I/R is unknown. METHODS AND RESULTS: We measured plasma ET-1 concentrations by radioimmunoassay in isolated blood-perfused neonatal lamb hearts before and after 2 hours of 10 degrees C cardioplegic ischemia and examined the effects of ET-1 and the endothelin-A (ET-A) receptor antagonist BE-18257B on the postischemic recovery of isolated hearts. ET-1 levels in coronary sinus blood before ischemia and at 0 and 30 minutes of reperfusion in 8 control hearts were constant (2.2 +/- 1.2 fmol/L, 2.2 +/- 1.3 fmol/L, and 2.5 +/- 1.0 fmol/L, respectively). In group 2 (n = 6), 10 mumol/L of BE-18257B was given just before reperfusion. In group 3 (n = 8), 10 pmol/L ET-1 was given just before the start of reperfusion. At 30 minutes of reperfusion, the ET-A antagonist hearts had significantly greater recovery of LV systolic (positive dP/dt and dP/dt at V10) and diastolic function (negative dP/dt), coronary blood flow (CBF), and MVo2 compared with controls (P < .05). The ET-1 hearts showed significantly reduced recovery of LV systolic (positive maximum and volume-normalized dP/dt) and diastolic (negative maximum dP/dt) function, CBF, and myocardial oxygen consumption compared with controls (P < .05). CONCLUSIONS: These results, combined with prior studies, suggest that I/R causes reduced production of endogenous vasodilators (eg, nitric oxide), leaving unopposed the vasoconstriction that is caused by the continued presence of ET-1. This imbalance may contribute to I/R injury. ET-A receptor antagonists may be useful therapeutic agents in reducing the injury that results from I/R.

Monocyte chemoattractant protein 1 acts as a T-lymphocyte chemoattractant.

We have utilized a transendothelial lymphocyte chemotaxis assay to identify and purify a lymphocyte chemoattractant in supernatants of mitogen-stimulated peripheral blood mononuclear cells. Amino acid sequence analysis revealed identity with monocyte chemoattractant protein 1 (MCP-1), a chemoattractant previously thought to be specific for monocytes. Recombinant MCP-1 is chemoattractive for purified T lymphocytes and for CD3+ lymphocytes in peripheral blood lymphocyte preparations. The T-cell response to MCP-1 is dose-dependent and chemotactic, rather than chemokinetic. Phenotyping of chemoattracted T lymphocytes shows they are an activated memory subset. The response to MCP-1 by T lymphocytes can be duplicated in the absence of an endothelial monolayer and the majority of T-lymphocyte chemotactic activity in mitogen-stimulated peripheral blood mononuclear cell supernatants can be neutralized by antibody to MCP-1. Thus, MCP-1 is the major lymphocyte chemoattractant secreted by mitogen-stimulated peripheral blood mononuclear cells and is capable of acting as a potent T-lymphocyte, as well as monocyte, chemoattractant. This may help explain why monocytes and T lymphocytes of the memory subset are always found together at sites of antigen-induced inflammation.

Resurgence of acute rheumatic fever in the intermountain area of the United States.

We describe an outbreak of acute rheumatic fever that occurred in the intermountain area centered in Salt Lake City, Utah. Seventy-four children meeting the modified Jones criteria for the diagnosis of acute rheumatic fever were evaluated by the staff at Primary Children's Medical Center, Salt Lake City, from January 1985 through June 1986. This represents an eightfold increase over the average annual incidence at this hospital during the past decade. Carditis, a dominant feature of the outbreak, was confirmed by auscultation in 53 of the patients (72 percent). An additional 14 patients were found to have mitral regurgitation by Doppler ultrasound examination, raising the total incidence of carditis to 91 percent. The children were predominantly from white (96 percent) middle-class families with above-average incomes and with ready access to medical care. There was no apparent increase in the incidence of streptococcal disease or other explanation for the marked increase in acute rheumatic fever. However, mucoid M type 18 and M type 3 group A streptococcal strains were isolated from several siblings of the patients and from schoolchildren (chosen at random) in the area. We conclude that acute rheumatic fever remains an important health problem in the United States.

Hypertrophic obstructive cardiomyopathy: hemodynamic improvement with intravenous verapamil.

We report the reduction in left ventricular outflow tract gradient following the intravenous administration of verapamil to two pediatric patients with hypertrophic obstructive cardiomyopathy. Traditional therapy with beta adrenergic antagonists was relatively contraindicated in both patients. In a 15-year-old patient, the left ventricular outflow tract gradient decreased from 160 torr, at rest, to 45 torr during the verapamil infusion. In a 3-year-old boy, there was a reduction in the left ventricular outflow tract gradient from 60 torr, under basal conditions, to 10 torr during the intravenous verapamil infusion. We believe that verapamil may be effective in reducing the left ventricular outflow tract gradient in some pediatric patients with hypertrophic obstructive cardiomyopathy and may be useful in treating selected patients with this disorder.