Managing chronic thromboembolic pulmonary hypertension: pharmacological treatment options

Chronic thromboembolic pulmonary hypertension (CTEPH) is a life-threatening condition in which organised thrombi obstruct the pulmonary vessels, causing increased pulmonary vascular resistance, progressive pulmonary hypertension (PH) and right heart failure. The treatment of choice is pulmonary endarterectomy, which restores pulmonary haemodynamics with acceptable periprocedural mortality rates in the majority of suitable patients. However, CTEPH may be inoperable owing to surgically inaccessible thrombi or comorbid diseases that confer an unacceptably high risk. Pharmacotherapies, although not yet approved, may be useful in this situation or for treating residual or recurrent PH following surgery. Vasodilator drugs for PH are attracting growing interest as potential treatments for CTEPH because this disease has recently been labelled as a "dual" pulmonary vascular disorder: major vessel obstruction and remodelling is combined with a small vessel arteriopathy that is histologically indistinguishable from the classical pulmonary arteriopathy observed in pulmonary arterial hypertension. Of three completed randomised controlled trials in patients with CTEPH, only one was powered to detect a treatment effect. The BENEFIT trial employed the dual endothelin-receptor antagonist bosentan. Although haemodynamics improved significantly, the second component of the primary end-point, exercise capacity, was not met. More evidence is required to resolve whether vasodilator treatments are beneficial for inoperable chronic thromboembolic pulmonary hypertension.

A noninvasive algorithm to exclude pre-capillary pulmonary hypertension

Current guidelines recommend right heart catheterisation (RHC) in symptomatic patients at risk of pre-capillary pulmonary hypertension (PH) with echocardiographic systolic pulmonary artery pressures ≥ 36 mmHg. Growing awareness for PH, a high prevalence of post-capillary PH and the inability to distinguish between pre- and post-capillary PH by echocardiography have led to unnecessary RHCs. The aim of our study was to assess whether standard noninvasive diagnostic procedures are able to safely exclude pre-capillary PH. Data from 251 patients referred for suspicion of pre-capillary PH were used to develop a noninvasive diagnostic decision tree. A prospectively collected data set of 121 consecutive patients was utilised for temporal validation. According to the decision tree, patients were stratified by the presence or absence of an electrocardiographic right ventricular strain pattern (RVS) and serum N-terminal brain natriuretic peptide (NT-proBNP) levels below and above 80 pg·mL⁻¹. In the absence of RVS and elevated NT-proBNP, none of the patients in the prospective validation cohort were diagnosed with pre-capillary PH by RHC. Combining echocardiography with the diagnostic algorithm increased specificity to 19.3% (p = 0.0009), while sensitivity remained at 100%. Employing ECG and NT-proBNP on top of echocardiography helps recognise one false positive case per five patients referred with dyspnoea and echocardiographic suspicion of PH, while not missing true pre-capillary PH.

Long-term outcome after thrombectomy in acute myocardial infarction

BACKGROUND

Current data appear in favour of thrombectomy for ST-elevation myocardial infarction (STEMI). However, information on long-term outcome after thrombectomy is limited. We performed a retrospective long-term study to assess the risk of cardiac re-hospitalizations and survival after discharge from the index hospitalization for STEMI.

METHODS

Patients originally randomized to percutaneous coronary intervention (PCI) with thrombectomy vs. standard PCI were included in a retrospective long-term observational study. The primary study endpoint was the combined risk for all-cause death or cardiac re-hospitalization after index discharge under optimal medical therapy. The cumulative number of cardiac hospitalization days and ventricular remodelling assessed by echocardiography and plasma biomarkers were secondary endpoints.

RESULTS

Of 94 STEMI patients who had been randomized between 11/2000 and 03/2003, 89 patients consented to long-term follow-up. A total of 43 patients had been allocated to thrombectomy and 46 to standard primary PCI. The minimum follow-up time was 1115 days. There was a significantly lower risk for death or cardiac re-hospitalization for patients of the thrombectomy group (hazard ratio = 0.69, 95% CI: 0.49-0.98, P = 0.036). The incidence of recurrent myocardial infarction was not different (P = 0.343). No differences in cardiac remodelling were detected by echocardiography, with the exception that heart-type fatty acid binding protein at 53.2 +/- 17 months was lower in the thrombectomy group (P = 0.045).

CONCLUSION

Thrombectomy in STEMI may decrease the long-term risk for death or cardiac re-hospitalization.

Multiple electrode aggregometry predicts stent thrombosis better than the vasodilator-stimulated phosphoprotein phosphorylation assay

BACKGROUND AND AIM

The prognostic value of the vasodilator-stimulated phosphoprotein (VASP) phosphorylation assay and multiple electrode aggregometry (MEA) for thrombotic adverse events has been shown in independent studies. As no direct comparison between the two methods has been made so far, we investigated which laboratory approach has a better predictive value for stent thrombosis.

METHODS

The VASP phosphorylation assay and MEA were performed in 416 patients with coronary artery disease undergoing percutaneous coronary intervention. The rate of stent thrombosis was recorded during a 6-month follow-up.

RESULTS

Definite stent thrombosis occurred in three patients (0.7%) and probable stent thrombosis in four (1%). Receiver operating characteristic (ROC) analysis demonstrated that MEA distinguishes between patients with or without subsequent stent thrombosis better than the VASP phosphorylation assay: the area under the ROC curve was higher for MEA (0.92; P=0.012) than for the VASP phosphorylation assay (0.60; P=0.55). At equal levels of sensitivity (100%), the specificity was greater for MEA than for the VASP phosphorylation assay (86% vs. 37%). Stent thrombosis occurred in 9% of patients with platelet hyperreactivity in MEA, who were simultaneously clopidogrel non-responders in the VASP phosphorylation assay. Interestingly, clopidogrel non-responders in the VASP phosphorylation assay without platelet hyperreactivity in MEA did not suffer from stent thrombosis.

CONCLUSIONS

Platelet hyperreactivity in MEA might be a better risk predictor for stent thrombosis than the assessment of the specific clopidogrel effect with the VASP phosphorylation assay.

Loss of high-molecular-weight von Willebrand factor multimers mainly affects platelet aggregation in patients with aortic stenosis

Severe aortic stenosis is associated with a haemostatic abnormality that resembles acquired von Willebrand syndrome type 2. It is assumed that high shear conditions render large von Willebrand factor (VWF) multimers accessible to cleavage by ADAMTS-13. However, whether loss of these large multimers affects platelet function by impairing adhesion, aggregate formation, or both has not been evaluated in clinical studies. We prospectively enrolled 47 patients with severe aortic stenosis, and studied them prior to aortic valve surgery and at a median of six months after valve replacement. We investigated levels of large VWF multimers, platelet function under high shear conditions, and residual response to suboptimal concentrations of ADP to express P-selectin. As expected, there was a significant reduction of VWF large multimers before surgery that resolved thereafter in most patients (p<0.0001). The closure time of the ADP cartridge of the PFA-100 was also corrected in most patients after the operation (p<0.0001). We used the cone and plate(let) analyser Impact-R to differentiate between adhesion and aggregation. Both adhesion (p=0.03) and ADP-inducible platelet aggregation (p=0.002) improved considerably after valve replacement. Consequently, ADP-inducible expression of P-selectin was higher after valve replacement (p=0.001). We conclude that reduced levels of large VWF multimers associated with aortic stenosis lead to impairment of both adhesion and, especially, ADP-inducible platelet aggregation.

Outcome after device implantation in chronic heart failure is dependent on concomitant medical treatment

BACKGROUND

Device implantation in chronic heart failure (CHF) for cardiac resynchronization therapy (CRT) with or without implantable cardioverter/defibrillator (ICD) is an established treatment option for symptomatic patients under medical baseline therapy. Although recommended, the need for optimization of medical therapy was never proven. As in 'the real world', medical therapy is not always up-titrated to the desirable dosages; this provides the opportunity to evaluate the impact of optimizing medical therapy in patients who had received a device therapy with proven effectiveness.

MATERIALS AND METHODS

This observational cohort study retrospectively assessed the 'real life'-effect of CRT compared with that of CRT/ICD therapy and the impact of concomitant pharmacotherapy on outcome. Outcome of patients with guideline recommended renin-angiotensin system inhibitor and ss-blocker dosages was compared with that of patients who failed to reach the desired dosages. Mean follow-up for the 205 CHF (95 CRT and 110 CRT/ICD) patients was 16.8 + or - 12.4 months.

RESULTS

In the total study cohort, 83 (41%) reached the combined primary endpoint of all-cause death or cardiac hospitalization [CRT group: 25 (26%), CRT/ICD group: 58 (52.7%), P < 0.001]. Multiple cox regression analysis revealed non-optimized medical therapy at follow-up [HR = 2.080 (1.166-3.710), P = 0.013] and CRT/ICD vs. CRT [HR = 2.504 (1.550-4.045), P < 0.001] as significant predictors of the primary endpoint.

CONCLUSION

Our data stress the importance of professional monitoring and titration of pharmacotherapy not only in medically treated CHF patients but also in patients under device therapy by a heart failure unit or a specialized cardiologist.

Pulmonary hypertension in chronic heart failure

The presence of PH in patients who suffer from CHF is common and predicts a poor outcome. However, precise definitions for PH associated with left heart disease, or 'out-of-proportion' PH as well as standardised vasodilator testing protocols are lacking. Moreover, apart from single-centre observations no large-scale trial to date has demonstrated a long-term benefit from pulmonary vasoactive drugs. As a result, there are currently no consensus recommendations for the treatment of PH in the presence of CHF. Off-label use of specific vasodilators in this patient population is discouraged. In a majority of cases, treatment of the underlying left heart disease leads to a decrease in pulmonary pressures. In light of novel agents to treat PH, trials that specifically address 'out-of-proportion' PH in CHF patients are warranted.

[Chronic thromboembolic pulmonary hypertension (CTEPH)]

The spectrum of venous thromboembolism encompasses deep vein thrombosis, acute thrombus passing through the right heart, acute pulmonary embolism and chronic thromboembolic pulmonary hypertension (CTEPH). Pulmonary embolism may recur and have severe sequelae, such as the post-thrombotic syndrome and CTEPH. It is thought at present, based on a long-term prospective study of about 300 patients, that CTEPH results within two years in 3.8% of patients who had survived the first symptomatic pulmonary embolism. Previous incidence of pulmonary embolism, young age, a large perfusion deficit and no known cause were associated with an increased probability of subsequent CTEPH. The diagnosis and treatment of CTEPH call for an interdisciplinary approach, the former still relying on finding a positive perfusion scan together with pulmonary hypertension. Treatment of choice is surgical endarterectomy of the pulmonary obstruction which will result in functional healing in 80% of patients.

Risk factors for chronic thromboembolic pulmonary hypertension

Chronic thromboembolic pulmonary hypertension (CTEPH) is characterised by nonresolving pulmonary thromboemboli that can be treated by surgical pulmonary endarterectomy (PEA). The authors of the present study sought to confirm known and to identify novel CTEPH risk factors in a controlled retrospective cohort study of prevalent CTEPH cases collected in three European centres offering PEA. Data from CTEPH patients were compared with nonthromboembolic pre-capillary pulmonary arterial hypertension cohorts at the participating institutions. The study population comprised 687 patients assessed at the time of diagnosis between 1996 and 2007. Ventriculo-atrial shunts and infected pacemakers (odds ratio (OR) 76.40, 95% confidence interval (CI) 7.67-10,351), splenectomy (OR 17.87, 95% CI 1.56-2,438), previous venous thromboembolism (VTE; OR 4.52, 95% CI 2.35-9.12), recurrent VTE (OR 14.49, 95% CI 5.40-43.08), blood groups other than 0 (2.09, 95% CI 1.12-3.94), and lupus anticoagulant/antiphospholipid antibodies (OR 4.20, 95% CI 1.56-12.21) were more often associated with CTEPH. Thyroid replacement therapy (OR 6.10, 95% CI 2.73-15.05) and a history of malignancy (OR 3.76, 95% CI 1.47-10.43) emerged as novel CTEPH risk factors. In conclusion, the European database study confirmed previous knowledge of chronic thromboembolic pulmonary hypertension risk factors, and identified thyroid replacement therapy and a history of malignancy as new medical conditions associated with chronic thromboembolic pulmonary hypertension.

Pulmonary embolism

Die akute Pulmonalembolie ist Teil des Spektrums venöser Thromboembolien. Die tiefe Beinvenenthrombose, der akute Thrombus in Transit durch das rechte Herz, die akute Pulmonalembolie selbst und die chronisch thromboembolische pulmonale Hypertension (CTEPH) gehören dazu. Pulmonalembolie kann rezidivieren und schwere Spätfolgen (z. B. postthrombotisches Syndrom, CTEPH) nach sich ziehen.

Diese Übersicht fasst aktuelle Konzepte zur Pathophysiologie, Epidemiologie, Diagnose und Therapie dieser häufigen Erkrankung zusammen.

Heart-type fatty acid-binding protein for risk assessment of chronic thromboembolic pulmonary hypertension

Heart-type fatty acid-binding protein (H-FABP) is a reliable marker of myocardial injury and was recently identified as a predictor of outcome in acute pulmonary embolism. The aim of the present study was to investigate the prognostic value of H-FABP in chronic thromboembolic pulmonary hypertension (CTEPH). In total, 93 consecutive patients with CTEPH were studied. During long-term follow-up (median duration 1,260 days, interquartile range (IQR) 708-2,460 days), 46 (49%) patients had an adverse outcome, defined as CTEPH-related death, lung transplantation or persistent pulmonary hypertension after pulmonary endarterectomy (PEA). Baseline H-FABP levels in plasma ranged from 0.69-24.3 ng x mL(-1) (median (IQR) 3.41 (2.28-4.86) ng x mL(-1)). Cox regression analysis revealed a hazard ratio of 1.10 (95% confidence interval 1.04-1.18) for each increase of H-FABP by 1 ng x mL(-1), and continuous elevations of H-FABP emerged as an independent predictor of adverse outcome by multivariable analysis. PEA was performed in 52 patients and favourably affected the long-term outcome. Kaplan-Meier analysis revealed that patients with baseline H-FABP concentrations >2.7 ng x mL(-1), the median value of the biomarker in the surgically treated population, had a lower probability of event-free survival after PEA. Heart-type fatty acid-binding protein is a promising novel biomarker for risk stratification of patients with chronic thromboembolic pulmonary hypertension.

Pulmonary embolism

The underlying disorder of pulmonary embolism (PE) is venous thromboembolism (VTE), comprising deep vein thrombosis, thrombus in transit, acute pulmonary embolism and chronic thromboembolic pulmonary hypertension (CTEPH). PE may recur and cause serious long-term complications, such as post-thrombotic syndrome and CTEPH. This short overview summarizes current concepts on pathophysiology, epidemiology, diagnosis and treatment of this common disorder.

Elevated levels of interleukin-1beta-converting enzyme and caspase-cleaved cytokeratin-18 in acute myocardial infarction

BACKGROUND

Systemic inflammation and apoptosis-specific immune activation play a major role in acute coronary syndromes (ACS) including acute myocardial infarction (AMI). The role of systemic and coronary obtained inflammatory plasma protein interleukin-1beta precursor (IL-1betap), IL-1beta-converting enzyme (ICE) and the apoptosis-specific caspase-cleaved cytokeratin-18 (ccCK-18) are not known in ACS.

MATERIALS AND METHODS

Plasma samples were obtained from stable angina (SA, n = 34), unstable angina (UA, n = 37) and patients with AMI (n = 39). Coronary blood was acquired by means of thrombectomy devices (X-sizer) in AMI patients. IL-1betap, ICE and ccCK-18 were determined by enzyme-linked immunosorbent assay (ELISA). Group comparisons were evaluated by parametric Tukey test. Multivariate logistic regression analysis was performed to determine predictive values of IL-1betap, ICE and ccCK-18 as compared to creatine kinase (CK) and troponin T (TnT) in order to relate these markers with the occurrence of myocardial damage.

RESULTS

IL-1betap, ICE and ccCK-18 were identified to be significantly altered in the peripheral blood of patients suffering from AMI as compared to SA and UA. ROC curves were plotted and revealed that ccCK-18 is a novel sensitive marker for the detection of myocardial damage as compared to TnT or CK. (AUC ccCK-18 0.925, TnT AUC 0.62 and CK AUC 0.858.) Moreover, ICE and ccCK-18 were significantly increased at the site of coronary occlusion as compared to peripheral blood samples in AMI patients (both P < 0.001).

CONCLUSION

Our data suggest that ACS is related to increased concentration of systemic soluble ICE and ccCK-18. Moreover, soluble ccCK-18 was identified to be a superior marker as compared to TnT or CK, for detection of myocardial damage.

Treprostinil for severe inoperable chronic thromboembolic pulmonary hypertension

BACKGROUND

Chronic thromboembolic pulmonary hypertension (CTEPH) results from non-resolving pulmonary thromboemboli that are resistant to plasmatic anticoagulation. Because of a secondary pulmonary arteriopathy accompanying major vessel obstruction, the disorder may be a target for vasodilator therapy.

OBJECTIVES

In an open-label uncontrolled study, we investigated the prostacyclin analog treprostinil given s.c. in patients with severe inoperable CTEPH.

METHODS

Between September 1999 and September 2005, 25 patients were included if their World Health Organization (WHO) functional class was III or IV, if their six-minute walking distance (6-MWD)

RESULTS

Treprostinil-treated patients demonstrated significant improvements in 6-MWD (P = 0.01), WHO functional class (P = 0.001), B-type brain natriuretic peptide plasma levels (P = 0.02), cardiac outputs (P = 0.007) and pulmonary vascular resistances (P = 0.01) after 19 +/- 6.3 months. Treprostinil plasma concentrations correlated with drug dose (P < 0.001), indicating stable absorption over time. Long-term survival was significantly better than in controls.

CONCLUSIONS

Treprostinil improves exercise capacity, hemodynamics and survival in patients with severe inoperable CTEPH. We speculate that the effects may be explained by a combined vasodilatory, platelet-antagonistic and potential antiproliferative action of the drug.

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Key Words Collapse

MESH Headings

• Aged
• Antihypertensive Agents/administration & dosage
• Antihypertensive Agents/blood
• Antihypertensive Agents/therapeutic use
• Cardiac Output/drug effects
• Case-Control Studies
• Chronic Disease
• Epoprostenol/administration & dosage
• Epoprostenol/analogs & derivatives
• Epoprostenol/blood
• Epoprostenol/therapeutic use
• Female
• Follow-Up Studies
• Humans
• Hypertension, Pulmonary/blood
• Hypertension, Pulmonary/drug therapy
• Hypertension, Pulmonary/etiology
• Hypertension, Pulmonary/mortality
• Infusion Pumps
• Kaplan-Meier Estimate
• Male
• Middle Aged
• Natriuretic Peptide, Brain/blood
• Odds Ratio
• Pain/drug therapy
• Pain/etiology
• Pain Measurement
• Platelet Aggregation Inhibitors/administration & dosage
• Platelet Aggregation Inhibitors/blood
• Platelet Aggregation Inhibitors/therapeutic use
• Proportional Hazards Models
• Prospective Studies
• Pulmonary Embolism/blood
• Pulmonary Embolism/complications
• Pulmonary Embolism/drug therapy
• Pulmonary Embolism/mortality
• Risk Assessment
• Severity of Illness Index
• Thromboembolism/blood
• Thromboembolism/complications
• Thromboembolism/drug therapy
• Thromboembolism/mortality
• Time Factors
• Treatment Outcome
• Vascular Resistance/drug effects
• Vasodilator Agents/administration & dosage
• Vasodilator Agents/blood
• Vasodilator Agents/therapeutic use
• Walking

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Grants Collapse

Bosentan therapy for pulmonary arterial hypertension associated with hereditary haemorrhagic telangiectasia

Hereditary haemorrhagic telangiectasia (HHT) is a disorder of arteriovenous malformations and telangiectases. In rare cases affected individuals may develop typical pulmonary arterial hypertension (PAH). Vasodilator therapy has not been recommended because of a potential increase in arteriovenous shunt volume. This report is on two patients with severe HHT-associated PAH who were treated with bosentan, an oral endothelin ET(A)/ET(B) receptor antagonist. After 1 year, symptomatic and functional improvements were confirmed by haemodynamic evaluation demonstrating a significant decrease of mean pulmonary artery pressures and an increase in cardiac index, without evidence for an increase in effective shunt volume.

Response properties of the brainstem neurons of the cat following intra-esophageal acid–pepsin infusion

Studies in humans have documented that acute acid infusion into the esophagus leads to decrease in threshold for sensations to mechanical distension of the esophagus. It is not known whether acid infusion leads to sensitization of brainstem neurons receiving synaptic input from vagal afferent fibers innervating the esophagus. The aim of this study was to investigate the correlation of responses of vagal afferents and brainstem neurons after acute infusion of acid (0.1 N HCl)+pepsin (1 mg/ml) into the esophagus of cats. The vagal afferent fibers (n=20) exhibited pressure-dependent increase in firing to graded esophageal distension (5-80 mm Hg). Infusion of acid+pepsin into the esophagus produced a significant increase in ongoing resting firing of five of 16 fibers (31%) tested. However, their responses to graded esophageal distension did not change when tested 30 min after infusion. Pepsin infusion did not change the resting firing and response to esophageal distension (n=4). Twenty-one brainstem neurons were recorded that responded in an intensity-dependent manner to graded esophageal distension. Responses of 12 excited neurons were tested after intra-esophageal acid+pepsin infusion. Neurons exhibited a decrease in threshold for response to esophageal distension and increase in firing after acid+pepsin infusion. The sensitization of response after intra-esophageal acid remained unaffected after cervical (C1-C2) spinal transection (n=3). Results indicate that the esophageal distension-sensitive neurons in the brainstem exhibit sensitization of response to esophageal distension after acute acid+pepsin exposure. The sensitization of brainstem neurons is possibly initiated by increased spontaneous firing of the vagal afferent fibers to acid+pepsin, but not to sensitized response of vagal distension-sensitive afferent fibers to esophageal distension. Results also indicate that spinal pathway does not contribute to sensitization of brainstem neurons.

Increased intimal apoptosis in coronary atherosclerotic vessel segments lacking compensatory enlargement

OBJECTIVES

In a histopathologic study, we assessed the balance of cell proliferation and apoptosis by counting the number of apoptotic and proliferating cell nuclear antigen-positive cells in freshly harvested atherectomy specimens from 34 patients.

BACKGROUND

Remodeling of human coronary arteries is an adaptive process that alters vascular lumen size.

METHODS

Intravascular ultrasound was performed prior to atherectomy. Total vessel area (area within the external elastic lamina [EEL]), lumen area and plaque area were measured at the region of interest (ROI), and at a proximal and distal reference segment, utilizing the formula Delta(%)=100x(ROI-reference segment)/reference segment. Positive arterial remodeling (R+) resulting in luminal expansion was defined as DeltaEEL >10%. Absence of remodeling (0 < DeltaEEL <10%) and constrictive arterial remodeling (DeltaEEL <0) were considered as neutral remodeling (R0) and negative remodeling (R-), respectively.

RESULTS

In R- lesions, apoptotic indices (APO) were significantly elevated (17.17 +/- 2.19%) compared with R+ lesions (4.89 +/- 1.7%; p = 0.0007). In a rabbit iliac percutaneous transluminal coronary angioplasty model intimal apoptosis was increased four weeks after balloon angioplasty injury (APO 8.8 +/- 0.03%) compared with contralateral untreated segments (APO 3.0 +/- 0.04%, n = 6). Lesions with an EEL/intimal area <3.0 showed significantly more intimal apoptosis than untreated lesions (p = 0.02).

CONCLUSIONS

The data indicate that constrictive remodeling of atherosclerotic coronary lesions is associated with increased apoptosis of intimal cells. We speculate that increased apoptosis is due to extensive plaque healing after episodes of symptomatic or asymptomatic plaque rupture.

Mechanisms of reflexes induced by esophageal distension

We investigated the mechanisms of esophageal distension-induced reflexes in decerebrate cats. Slow air esophageal distension activated esophago-upper esophageal sphincter (UES) contractile reflex (EUCR) and secondary peristalsis (2P). Rapid air distension activated esophago-UES relaxation reflex (EURR), esophago-glottal closure reflex (EGCR), esophago-hyoid distraction reflex (EHDR), and esophago-esophagus contraction reflex (EECR). Longitudinal esophageal stretch did not activate these reflexes. Magnitude and timing of EUCR were related to 2P but not injected air volume. Cervical esophagus transection did not affect the threshold of any reflex. Bolus diversion prevented swallow-related esophageal peristalsis. Lidocaine or capsaicin esophageal perfusion, esophageal mucosal layer removal, or intravenous baclofen blocked or inhibited EURR, EGCR, EHDR, and EECR but not EUCR or 2P. Thoracic vagotomy blocked all reflexes. These six reflexes can be activated by esophageal distension, and they occur in two sets depending on inflation rate rather than volume. EUCR was independent of 2P, but 2P activated EUCR; therefore, EUCR may help prevent reflux during peristalsis. All esophageal peristalsis may be secondary to esophageal stimulation in the cat. EURR, EHDR, EGCR, and EECR may contribute to belching and are probably mediated by capsaicin-sensitive, rapidly adapting mucosal mechanoreceptors. GABA-B receptors also inhibit these reflexes. EUCR and 2P are probably mediated by slowly adapting muscular mechanoreceptors. All six reflexes are mediated by vagal afferent fibers.

Der Einfluss der Sexualhormone auf die Gefäßbiologie der Venen

Die wichtigsten Erkrankungen der Venen stellen Varikose, Thrombose und Phlebosklerose, in diesem Artikel als chronisch-venöse Erkrankung (CVE) bezeichnet, dar. Es ist unklar, wie Varikose entsteht. Die Forschung der letzten Jahre hat gezeigt, dass Gefäßerkrankungen die Folge von Gefäßwandumbauvorgängen darstellen. Diese werden von molekularen Mechanismen gesteuert. Da das Auftreten von Varikose klinisch mit Schwangerschaft und Hormonapplikation koinzidiert, beschäftigt sich der folgende Artikel mit den Wirkungen von Sexualhormonen auf bekannte Proteine, die das Gefäßremodeling steuern. Derzeit sind die Schlüsselmechanismen des vaskulären Remodelings der Venen noch nicht ausreichend erforscht, um eine direkte Umsetzung in die praktische Medizin zu rechtfertigen.

Long-term treatment of pulmonary hypertension with aerosolized iloprost

Pulmonary arterial hypertension (PAH), defined as elevated pulmonary arterial pressure and pulmonary vascular resistance, is an end-point of a variety of conditions. The only therapy that has been shown to improve both quality of life and survival is intravenous prostacyclin (prostaglandin I2 (PGI2), epoprostenol). The effect of long-term aerosolized iloprost (Ilomedin, Schering, Berlin, Germany and Vienna, Austria), a stable prostacyclin analogue and potent vasodilator, on haemodynamics and functional status was investigated in 12 patients with severe pulmonary hypertension. Haemodynamic measurements and vasodilator testing by right heart catheterization were performed prior to and after long-term iloprost inhalation therapy. Haemodynamic improvement or increased exercise tolerance was not observed in any of the patients. After a mean+/-SD treatment period of 10+/-5 months, mean+/-SD pulmonary vascular resistance had increased from 11+/-3 Wood Units (mmHg.L(-1).min) to 13+/-4 Wood Units, with unchanged arterial oxygen saturation (92+/-4%, versus 91+/-4%). Within the study period, three patients went into right heart failure and had to be placed on intravenous epoprostenol. The authors conclude that inhaled iloprost in addition to conventional therapy in the presently recommended dose of 100 microg.day(-1) delivered in 8-10 2 h portions, is not an efficient vasodilator therapy in severe pulmonary hypertension. It remains to be shown whether dose increases and/or combination protocols will be effective, or whether inhalation of iloprost may be safe for selected cases of pulmonary hypertension.

Deterioration of the pharyngo-UES contractile reflex in the elderly

OBJECTIVES/HYPOTHESIS

Deterioration of aerodigestive tract reflexes such as the esophagoglottal and pharyngoglottal closure reflexes and pharyngeal swallow has been documented in the elderly. However, the effect of aging on the contractile response of the upper esophageal sphincter (UES) to pharyngeal water stimulation has not been studied. The aim of this study was to characterize the pharyngo-UES reflex in the healthy elderly.

METHODS

We studied nine healthy elderly (77 +/- 1 y [SD]; four men, five women) and nine healthy young volunteers (26 +/- 2 y [SD]; four men, five women). AUES sleeve sensor was used to measure the pressure. We tested pharyngeal stimulation induced by rapid pulse and slow continuous injection of water.

RESULTS

The volume of water required to stimulate the pharyngo-UES contractile reflex by rapid pulse injection in the elderly (0.5 +/- 34 0.1 mL) was significantly higher than that in the young (0.1 +/- 0.02 mL) (P < .05). In contrast to young subjects, there was no pressure increase in resting UES pressure observed in the elderly for continuous pharyngeal water infusion. In both young and elderly, the threshold volume for the pharyngo-UES contractile reflex was significantly lower than that for pharyngeal swallows.

CONCLUSIONS

The pharyngo-UES contractile reflex deteriorates with aging. This deterioration is primarily due to abnormalities of the afferent limb of the reflex.

An overview of the upper esophageal sphincter

The anatomy and physiology of the upper esophageal sphincter (UES) are complex. Much progress has been made over the past few years in our understanding this important sphincter. The closing muscles of the UES include the inferior pharyngeal sphincter, the cricopharyngeus (CP), and the cervical esophagus. The CP is composed of two parts, which may have different functions. The CP is innervated by the pharyngeal plexus and the recurrent laryngeal nerve. Tone of the UES is probably generated by numerous reflexes rather than by specific tone-generating circuitry. The major tone-generating muscle is the CP, which is highly elastic and produces more active tension the more it is stretched. The UES opens by relaxation of the closing muscles, traction by muscles attached to the hyoid bone and thyroid cartilage, and pulsion of the bolus. The various muscles of the UES behave differently during its many dynamic states, so that similar functions are accomplished by different muscles.

Pharyngeal dysphagia in postesophagectomy patients: correlation with deglutitive biomechanics

BACKGROUND

Because of the transient nature of pharyngeal phase dysphagia, posttranshiatal esophagectomy patients provide a model for studying the correlation of dysphagic symptoms and aspiration with deglutitive biomechanics.

METHODS

We studied 8 transhiatal esophagectomy patients (age range, 51 to 78 years) and 8 normal age-matched controls in upright position using lateral and anteroposterior (AP) projection videofluoroscopy during three 5 mL barium swallows.

RESULTS

The maximum upper esophageal sphincter (UES) AP diameter and maximum anterior excursion of the hyoid bone in patients with transhiatal esophagectomy who experienced aspiration (6.2+/-0.6 and 9.0+/-2.0 mm, respectively) were significantly smaller than those of age-matched normal controls (9.4+/-0.7 and 17.0+/-1.0 mm, respectively). Resolution of aspiration was associated with a significant increase in AP diameter of the UES as well as anterior and superior excursion of the hyoid bone (p<0.05).

CONCLUSIONS

Dysphagic symptoms and aspiration in posttranshiatal esophagectomy patients are associated with significant abnormalities of deglutitive biomechanics. Improvement in deglutitive biomechanics is associated with resolution of dysphagic symptoms as well as postdeglutitive aspiration in these patients.

Accumulation of oxidized LDL in human semilunar valves correlates with coronary atherosclerosis

OBJECTIVE

Recent data indicate that oxidized low-density lipoprotein (ox-LDL) has several proatherogenic effects, e.g. induction of macrophage chemoattractants, adhesion molecules, cytokines, type-1 plasminogen activator inhibitor and platelet-derived growth factor A-chain by smooth muscle cells. Therefore, ox-LDL has been utilized as a marker of oxidative modification of proteins in atherosclerosis. Because heart valves consist of smooth muscle cells, fibroblasts and endothelial cells, and because valvular disease and coronary atherosclerosis could result from similar biological processes, we investigated ox-LDL accumulation in isolated aortic and pulmonary valves and coronary arteries from patients with angiographically proven coronary heart disease (CHD, n = 19), patients with idiopathic congestive heart failure (IDCM = idiopathic dilated cardiomyopathy, n = 20), and transplant donors.

METHODS

Masson-Goldner staining and immunohistochemistry utilizing anti ox-LDL and CD68 were performed on paraffin sections of freshly isolated semilunar valves. Data were analyzed by digital image planimetry and by visual scoring of staining intensity.

RESULTS

Ox-LDL immunoreactivity was identified in the vascular aspect of the attachment line, in the deep valve stroma, and in the ventricular and vascular endothelium of the semilunar valves, colocalizing with macrophages. Valvular ox-LDL area was significantly increased in CHD-patients (P < 0.03) and IDCM-patients (P < 0.04) compared with controls. More ox-LDL was accumulating in the pulmonary valves than in the aortic valves (P = 0.04) as assessed by area and staining intensity. Valvular ox-LDL area in pulmonary valve and aortic valve was significantly correlated with ox-LDL accumulation in the intimal layer (P < 0.001) and medial layer (P < 0.001) of coronary arteries from the same patients.

CONCLUSION

The data suggest that the biological process leading to ox-LDL accumulation in coronary atherosclerosis also involves heart valves. Therefore, accumulation of the oxidative stress marker ox-LDL in heart valves illustrates atherosclerosis as an additional mechanisms accelerating valvular degeneration in these patients.

Expression of the angiogenic protein, platelet-derived endothelial cell growth factor, in coronary atherosclerotic plaques: In vivo correlation of lesional microvessel density and constrictive vascular remodeling

Recent information indicates that platelet-derived endothelial cell growth factor (PD-ECGF), a 45-kDa angiogenic protein, is expressed in the endothelium of various tissues and that its level of expression is correlated with the number of microvessels in human tumors. Because the formation of neovessels is also thought to play a role in atherosclerotic vascular remodeling, we analyzed PD-ECGF expression in fresh, coronary plaque tissues obtained by directional coronary atherectomy. Specimens from 31 patients were collected and analyzed by reverse transcription-polymerase chain reaction, histochemical staining, immunohistochemistry, and in situ hybridization with the use of PD-ECGF-specific primers and probes. Lesional vascular remodeling was assessed by intravascular ultrasound. PD-ECGF immunoreactivity and mRNA were found in plaque macrophages, endothelial cells of plaque neovessels, and stellate smooth muscle cells of 20 atherectomy specimens (64.5%). PD-ECGF immunoreactivity was correlated with the number of lesional microvessels and mast cells. Double-staining experiments revealed a close spatial proximity of PD-ECGF-positive cells and mast cells. Furthermore, the numbers of microvessels and mast cells were significantly higher in lesions lacking compensatory enlargement. The data indicate that PD-ECGF is expressed within cells of the atherosclerotic plaque and may be involved in driving angiogenesis in concert with mast cells.

Gastrointestinal motor and myoelectric correlates of motion sickness

The objectives of this study were to characterize the digestive tract motor and myoelectric responses associated with motion sickness. Twenty-two cats (1.5-3.0 kg) were chronically implanted with force transducers and electrodes on the stomach and small intestine. Motion sickness was activated by vertical oscillation (VO) at +/-0.5 g and identified as salivation, licking, or vomiting. Vomiting was initiated chemically by UK-14304 (2.5-15 microg/kg iv) or CuSO4 (10-50 mg ig). We found that VO caused vomiting (45% of trials), a decrease in gastrointestinal (GI) motility (69% of trials), salivation or licking (59% of trials), bradygastria (39% of trials), retrograde giant contraction (RGC, 43% of trials), giant migrating contraction (GMC, 5% of trials), and defecation (18% of trials). The decrease in GI motility occurred with (62% of trials) or without (69% of trials) vomiting. Motion sickness was accompanied by bradygastria (52% of trials) and decreased GI motility (70% of trials). Similar events occurred after CuSO4 and UK-14304, but the incidences of responses after CuSO4 were less frequent, except for vomiting, RGC, and GMC. UK-14304 never caused GMCs or defecation. The magnitude and velocity of the RGC were the same during all emetic stimuli, and RGCs never occurred without subsequent vomiting. Supradiaphragmatic vagotomy (n = 1) or atropine (n = 2, 10 or 50 microg/kg iv) blocked the RGC, but not vomiting, due to VO. We concluded that 1) oculovestibular stimulation causes digestive tract responses similar to other types of emetic stimuli, 2) decreased GI motility and bradygastria may be physiological correlates of the motion sickness, and 3) motion sickness may not be dependent on any specific GI motor or myoelectric response.

Noxious stimulation of emesis

This review will focus on the mechanisms of emesis initiated or inhibited from receptors located in the periphery or activated by a peripherally released humoral factor. Excitatory and inhibitory receptors have been found in the thorax. Nausea and vomiting sometimes occur after coronary artery occlusion or with vasovagal syncope, and the receptors of this emetic response are probably tension receptors of the left ventricle. The thorax is also source of antiemetic receptors. Vagal section above the level of the heart causes an intractable vomiting syndrome and central cervical vagal stimulation inhibits vomiting. In addition, respiratory maneuvers that decrease activation of pulmonary afferents enhance the sensitivity to motion sickness. Therefore, pulmonary vagal afferent fibers may tonically inhibit retching and vomiting. Abdominal stimulation by irritants or toxins can activate nausea and vomiting through mechano- or chemoreceptors. Mechanoreceptors have been found in the stomach, jejunum and ileum, but the location of these receptors in the gut wall or the type of mechanical stimuli most effective in exciting these receptors is unknown. The chemoreceptors have a similar distribution and are probably located in the mucosa and respond to a variety of noxious agents, eg, CuSO4. CuSO4-induced vomiting is mediated by peripheral 5-HT4 receptors. Two clinically relevant toxic stimuli, x-irradiation and chemotherapeutic agents, have been found to activate vomiting through 5-HT3 receptors in the digestive tract. Regardless of the stimulus, the afferent neural pathways mediating emesis from the abdomen may be the same. The noxious stimulus may cause release of serotonin from enterochromaffin cells of the digestive tract, which activates visceral afferents. The vagus nerves mediate responses from the stomach and proximal small intestine and the splanchnic nerves and spinal cord mediate responses from the entire small intestine. Emesis-related afferents from the periphery terminate primarily in the nucleus tractus solitarius and area postrema. The area postrema contains the chemoreceptive trigger zone that can be activated by endogenous agents released into the circulation from the periphery. The role of peripheral receptors or peripherally released agents in the etiology of cyclic vomiting is unknown, but multiple pathways have been identified that can form a brain-gut interaction to provide a possible mechanism of cyclic vomiting.

Mechanisms underlying aortic dilatation in congenital aortic valve malformation

BACKGROUND

The high incidence of aortic disease in subjects with congenital aortic valve malformations suggests a causative relationship between these 2 conditions. The histological observation in aortic dilatation/aneurysm/dissection is Erdheim cystic medial necrosis (CMN), a noninflammatory loss of smooth muscle cells (SMCs), fragmentation of elastic fibers, and mucoid degeneration.

METHODS AND RESULTS

To examine whether apoptosis is 1 of the mechanisms underlying CMN and aortic medial layer SMC loss, ascending aortic wall specimens from 32 patients were collected at cardiothoracic surgery and examined by histochemical staining and terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick end labeling. From echocardiography results, 4 groups of patients were identified: bicuspid valve carriers with (bi/dil) or without (bi/0) aortic dilatation and tricuspid valve carriers with (tri/dil) or without (tri/0) aortic dilatation. Massive focal apoptosis was observed in the medial layers of bi/dil (mean apoptotic index [mAI], 8.1+/-6.0) and tri/dil (mAI, 8.1+/-8.3) compared with tri/0 (mAI, 0.9+/-1.2; P=0.0079 and P=0.037). In bi/0 (mAI, 9.1+/-5.7) compared with tri/0 (mAI, 0.9+/-1.2), rates of medial SMC apoptosis were increased (P=0.0025). Bi/dil (mean age, 40. 6+/-15.7 years) were significantly younger than tri/dil (mean age, 56.4+/-12.8 years) undergoing the same operation (P=0.0123).

CONCLUSIONS

Premature medial layer SMC apoptosis could be part of a genetic program underlying aortic disease in patients with aortic valve malformations.

MR imaging of paediatric uterovaginal anomalies

BACKGROUND

Transabdominal ultrasound (US) has not proved completely reliable in Müllerian duct anomalies. One study has shown it useful in obstructed uterovaginal anomalies. We are unaware of a study that has used endovaginal ultrasound in children to investigate uterovaginal anomalies. Magnetic resonance imaging (MRI) is now gaining wide acceptance in imaging congenital abnormalities of the genital tract.

OBJECTIVE

To identify the problems and potential pitfalls of using MRI to evaluate the female genital tract in paediatric patients.

MATERIALS AND METHODS

A retrospective review of the MRI scans of 19 patients, aged 3 months to 19 years (mean 14 years), with uterovaginal anomalies.

RESULTS

The uterovaginal anomalies were categorised into three groups: (1) congenital absence of the Müllerian ducts, or the Mayer-Rokitansky-Kuster-Hauser syndrome (n = 7), (2) disorders of vertical fusion (n = 2) and (3) disorders of lateral fusion (n = 10).

CONCLUSIONS

MRI is a reliable method for evaluating paediatric uterovaginal anomalies, but should be analysed in conjunction with other imaging modalities (US and genitography). Previous surgery makes interpretation more difficult and, if possible, MRI should be carried out prior to any surgery. An accurate MRI examination can be extremely helpful prior to surgery and it is important for the radiologist to have knowledge of how these complex anomalies are managed and what pitfalls to avoid.

Characterization and mechanisms of the pharyngoesophageal inhibitory reflex

The objectives of this study were to identify and to characterize the pharyngoesophageal inhibitory reflex (PEIR) in an animal model. Thirty-one cats (2.4-5.0 kg) were anesthetized using alpha-chloralose (45 mg/kg ip), and esophageal peristalsis was recorded manometrically. Secondary peristalsis was activated by rapid air injection (8-20 ml) at midesophagus or slow infusion of water through the manometric catheters. Neither stimulus activated primary peristalsis. The PEIR was activated by rapid water injection or focal mechanical stimulation of the pharynx. Rapid air injection activated secondary peristalsis in 92% of the trials, and slow water infusion activated 1 secondary peristalsis every 3.2 min. Pharyngeal stimulation by 0.3, 0.5, 0.8, or 1.0 ml of water inhibited or blocked ongoing secondary peristalsis in 67, 82, 97, or 93% of trials, respectively. Mechanical stimulation of the posterior wall of the pharynx with 11-20 g pressure attenuated secondary peristalsis in 96% of the trials or blocked secondary peristalsis in 41% of the trials. Centripetal electrical stimulation at 30 Hz, 0.2 ms, 2 V for 4 s of the superior laryngeal (SLN) or glossopharyngeal (GPN) nerves blocked or inhibited secondary peristalsis in 100% of the trials. Bilateral transection of the GPN (n = 8), but not the SLN (n = 6), blocked the PEIR. Anesthetization of the pharyngeal mucosa using lidocaine (2%) blocked the PEIR (n = 3). We concluded that 1) the PEIR exists in the cat, 2) mechanical stimulation of the pharynx more strongly activates the PEIR than water, 3) activation of either SLN or GPN afferents attenuates ongoing secondary peristalsis, 4) the receptors mediating the PEIR are located in the pharyngeal mucosa, and 5) both SLN and GPN contribute to the PEIR, but the GPN is the major afferent limb of this reflex.

Pharyngoglottal closure reflex: identification and characterization in a feline model

Earlier studies in humans have shown that pharyngeal stimulation by water at a threshold volume induces a brief vocal cord adduction, i. e., pharyngoglottal closure reflex. The present study was undertaken to 1) develop a suitable animal model for physiological studies of this reflex and 2) delineate its neural pathway and effector organs. Studies were done in cats by concurrent videoendoscopy and manometry followed by electromyographic studies. At a threshold volume (0.3 +/- 0.06 ml), injection of water into the pharynx resulted in a brief closure of the vocal folds, closing the introitus to the trachea. Duration of this closure averaged 1.1 +/- 0.1 s. Bilateral transection of the glossopharyngeal nerve completely abolished this reflex but not swallows induced by pharyngeal water stimulation. The pharyngoglottal closure reflex is present in the cats. The glossopharyngeal nerve is the afferent pathway of this reflex, and the interarytenoid and lateral cricoarytenoid muscles are among its target organs.

Plasma Lp(a) levels are increased in patients with chronic thromboembolic pulmonary hypertension

Chronic thromboembolic pulmonary hypertension (CTEPH) is a disease resulting from the thromboembolic obstruction of the segmental and/or large size pulmonary arteries, subsequently leading to pulmonary arterial hypertension. Incomplete resolution of acute pulmonary emboli and thrombus organization are believed to be important for the development of the disease. Primary pulmonary hypertension (PPH) is a further disease that at present is poorly understood but shows a clinical picture similar to CTEPH. Since lipoprotein(a) [Lp(a)]. a genetically determined risk factor for atherosclerosis and thrombosis, has been found increased in plasma of patients with deep vein thrombosis and pulmonary embolism, we measured plasma Lp(a) levels in 40 patients with CTEPH and 50 patients with PPH and compared them to 50 matched controls. The median for Lp(a) plasma levels was significantly higher in CTEPH patients (26.6 mg/dl) than in PPH patients (9.6 mg/dl) and controls (7.2 mg/dl). Increased plasma Lp(a) could, therefore. play a significant role in the mechanisms of ongoing thrombosis and thrombus organization in CTEPH, while its possible role in PPH can be limited to a small number of patients.

Elevated expression of urokinase-like plasminogen activator and plasminogen activator inhibitor type 1 during the vascular remodeling associated with pulmonary thromboembolism

Information is lacking on the mechanisms involved in the organization, resolution, and repair of the vascular lumen after acute pulmonary thromboembolism. Because recent data suggest that the balance between plasminogen activators (PAs) and type 1 plasminogen activator inhibitor (PAI-1) plays a role in regulating cell migration within the extracellular matrix, we investigated the expression of these molecules by immunohistochemical and in situ hybridization analysis of pulmonary artery specimens from patients suffering fatal pulmonary embolism. The data were compared with the expression of these molecules in both patients' noninvolved pulmonary arteries and organ donor pulmonary arteries. Regions of initial organization and vascular remodeling were identified by a modified trichrome stain and by the presence of proliferating cell nuclear antigen (PCNA), a cell marker of proliferation. Staining for tissue-type PA antigen was low to undetectable in endothelial cells directly in contact with the fibrin-platelet thromboembolus and in areas in which the endothelial cell lining was replaced by cell growth into the thrombus. Urokinase-like PA (u-PA) expression was detected in mononuclear cells within the thrombus in the initial phase of thromboembolism and within cells migrating into the thrombus during the later stages of organization. PAI-1 expression was elevated in the monolayer of endothelial cells underlying the fresh platelet-fibrin thromboembolus and in a PCNA-positive cell population present between the pulmonary arterial intima and the thromboembolus that represents early organization. Increased expression of PAI-1 may play a role in inhibiting proteolysis and fostering the localization of the acute fibrin-platelet thrombus to the vascular wall, which is followed by the upregulation of u-PA in migrating cells during the reorganization process.

Anatomy and physiology of the upper esophageal sphincter

The upper esophageal sphincter (UES) is composed of the cricopharyngeus (CP), thyropharyngeus (TP; inferior pharyngeal constrictor [IPC] in humans), and cranial cervical esophagus. All 3 muscles may at times function to maintain tone in the UES, but only the CP contracts and relaxes in all physiologic states consistent with the UES. The CP is a striated muscle composed of variable-sized small (25-35 microm) muscle fibers that are primarily type I (slow twitch), highly oxidative, and contain abundant (40%) endomysial elastic connective tissue. The fibers may attach to the connective tissue framework, forming a muscular net. In humans and rats, but not other animals, the CP has no median raphe. The optimum length of the CP for development of active tension is about 1.7 times resting length; therefore, in some respects the CP acts more like cardiac than striated muscle. A passive tone in the CP is present and increases through all degrees of stretch. The high compliance of the CP allows it to be opened by distraction of other muscles (e.g., geniohyoideus) or increased intraluminal pressure. The CP is innervated by branches of the vagus nerves: pharyngoesophageal (PE), superior laryngeal (SLN), and recurrent laryngeal (RLN); glossopharyngeal (GPN); and cervical sympathetics. Only the PE and SLN provide motor fibers to the CP. The GLN may be sensory; the sympathetics may innervate the mucosa, blood vessels, and glands; but no functional innervation by the RLN has been identified. Parasympathetic ganglia and various peptides (galanin, cGRP, VIP, neuropeptide Y, substance P, tyrosine hydroxylase) have been found in the CP, but their role in control of the CP is unknown. The motoneurons of the CP are found in the nucleus ambiguus, and the innervation is ipsilateral for animal species in which the CP has a median raphe. These motoneurons are topographically organized with other pharyngeal and laryngeal muscles and the striated muscle esophagus. Pharyngeal motoneurons often have a respiratory rhythm, but not a spontaneous background discharge. Therefore, the CP motoneurons may not generate CP tone. Various reflexes control the tone of the CP. Distension of the esophagus causes contraction of the CP and UES, which is mediated by a vago-vagal reflex. Pressure on the pharyngeal mucosa contracts the CP and UES and is mediated by a glossopharyngo-vagal reflex. Inflation of the lungs causes contraction of the CP and UES, which is mediated by a vago-vagal reflex. The pharyngo-UES and pulmonary-UES reflexes may generate the respiratory rhythm often observed on UES pressure or electromyographic activity. The UES or CP also contracts with arousal or with changes in posture. All of these reflexes and responses and the passive elastic properties of the CP may contribute to the generation of tone in the CP and UES.

Characterization of the pharyngo-UES contractile reflex in humans

Preliminary human studies suggest the presence of an upper esophageal sphincter (UES) contractile reflex triggered by pharyngeal water stimulation. The purposes of this study were to further characterize this reflex and determine the threshold volume for its activation. We studied 10 healthy young volunteers by manometric technique before and after topical pharyngeal anesthesia. UES pressure responses to various volumes and temperatures of water injected into the pharynx were elucidated. At a threshold volume, rapid-pulse and slow continuous pharyngeal water injection resulted in significant augmentation of UES pressure in all volunteers. Threshold volume for inducing UES contraction averaged 0.1 +/- 0.01 ml for rapid-pulse injection and was significantly smaller than that for slow continuous injection (1.0 +/- 0.2 ml). UES pressure increase duration averaged 16 +/- 4 s. Augmentation of UES resting tone by injection of water with three different temperatures was similar. This augmentation was abolished after topical anesthesia. Conclusions were that stimulation of the human pharynx by injection of minute amounts of water results in a significant increase in resting UES pressure: the pharyngo-UES contractile reflex. The magnitude of pressure increase due to activation of this reflex is not volume or temperature dependent. Loss of pharyngeal sensation abolishes this reflex.

Correlation of electrical and contractile activities of the cricopharyngeus muscle in the cat

We correlated the electrical and contractile activities of the cricopharyngeus (CP) to better understand the function of the CP and the upper esophageal sphincter (UES). In 40 decerebrate cats, we recorded resting and active tension of the CP and CP force and electromyographic (EMG) activity simultaneously during electrical stimulation of the pharyngoesophageal (PE) nerve, esophageal distension, or swallowing. In six intact cats, the change in diameter of the UES during food swallows was determined in two planes using videofluoroscopy. We found that resting tension of the CP developed quickly with stretch, and the strain-energy function, y = 6.5e3.4(z-1), fit (r = 0.94 +/- 0.06) this relationship. Active tension peaked at 1.68 +/- 0.03 times resting length, which is greater than the maximum distension during swallowing. Activation and relaxation of the CP occurred in approximately 50 and 120 ms, respectively. PE nerve stimulation bilaterally caused a force equal to approximately 90% of the summed force generated by separate stimulation of each PE nerve. The magnitude of the EMG response of the contralateral CP was approximately 18% of the ipsilateral response to unilateral PE nerve stimulation. We conclude that the CP exhibits tension throughout its physiological range of stretch. The CP functions more like a bilateral than a single contiguous muscle, and more like cardiac than striated muscle with regard to its passive elastic properties.

MRI appearances of dysplasia epiphysealis hemimelica of the knee

OBJECTIVE

The study was undertaken to describe the magnetic resonance imaging (MRI) appearances of dysplasia epiphysealis hemimelica (DEH) of the knee and to determine whether MRI provides additional information concerning the anomaly compared with more traditional methods of diagnosis.

DESIGN AND PATIENTS

The subjects of the study were three children (one girl and two boys, aged 13 months, 3 years and 11 years) with DEH of the knee. All the patients had plain films of the knee and MRI scans.

RESULTS AND CONCLUSION

Plain radiographs showed bone overgrowth and asymmetrical ossification centres with adjacent scattered calcifications which coalesced to form a lobulated irregular mass. MRI showed a definite cartilaginous or osteocartilaginous lesion. Its origin from the epiphysis was much more clearly defined. MRI showed the extent of the lesion non-invasively, as well as any potential cleavage plane between the epiphysis and the mass lesion. Abnormal surface nodularity and joint involvement could be determined. It is concluded that plain films supplemented with MRI provide the greatest amount of diagnostic information in cases of DEH. MRI is useful to show the exact location and extent of the lesion, any joint involvement and any potential cleavage between the epiphysis and the mass lesion.

Central inhibition of nitric oxide synthase modulates upper gastrointestinal motor activity

We investigated the role of central nitric oxide (NO) synthase inhibition in the modulation of fasting gastrointestinal motor activity and gastric emptying rate of solid nutrient meals in conscious dogs. N(omega)-nitro-L-arginine methyl ester and N(omega)-nitro-L-arginine were infused intracerebroventricularly. Circular muscle contractions were recorded with surgically implanted strain gauge transducers. Gastric emptying was measured by a radiolabeled meal. The inhibition of NO synthase in the brain suppressed phase III activity in the stomach and the duodenum but not in the jejunum or the ileum. However, the central inhibition of NO synthase had no significant effect on the rate of gastric emptying of solid nutrient meals or the duration of postprandial disruption of migrating motor complex cycling. The central actions of NO synthase inhibition were blocked by bilateral truncal vagotomy but not by intravenous administration of propranolol or phentolamine. We conclude that the inhibition of NO synthase in the brain generates a stimulus that selectively inhibits gastric and duodenal phase III activities. This stimulus, however, may not affect the postprandial gastroduodenal motor activity or the rate of gastric emptying of solid nutrient meals.

MRI appearance of popliteal cysts in childhood

Popliteal cysts are soft fluid-filled lesions of synovial origin which result from extrusion of joint fluid into the gastrocnemiosemimembranous bursa. They may occur in any age group, but 22-33 % occur in the first 15 years of life. In this age group they are rarely associated with intraarticular abnormalities and therefore rarely require treatment. This case report shows the magnetic resonance imaging (MRI) appearances of a popliteal cyst in two children.

Expression of Kunitz protease inhibitor--containing forms of amyloid beta-protein precursor within vascular thrombi

BACKGROUND

The presence of patent neovessels within vascular occlusions in chronic thromboembolic pulmonary hypertension suggests that local mechanisms exist to regulate the coagulation system. This study investigated the expression of a potent inhibitor of Factor IXa and Factor XIa (ie, protease nexin-2/ amyloid beta-protein precursor, A beta PP) in the organized vascular occlusions harvested from patients with this disease.

METHODS AND RESULTS

Immunohistochemical analysis revealed intense immunoreactivity for A beta PP in the single layer of cells that line the neovessels. A positive signal was also detected by in situ hybridization analysis with the use of a 35S-UTP-labeled antisense riboprobe that recognizes the various alternatively spliced mRNA forms of this molecule. To identify the forms of A beta PP produced within the thrombi, total RNA was extracted from the thrombi, reverse transcribed, and subjected to amplification with the use of the polymerase chain reaction (PCR) and primers that flank the region encoding the alternatively spliced 56-amino acid Kunitz-type protease inhibitor (KPI) domain. The major PCR products consisted of 255 bp and 312 bp and corresponded to transcripts encoding this domain (ie, A beta PP751 and A beta PP770). In situ hybridization analysis with the use of a 35S-UTP-labeled antisense riboprobe complementary to the region encoding the KPI domain confirmed the presence of these mRNA species in nucleated cells lining the neovessels.

CONCLUSIONS

The expression of KPI-containing isoforms of A beta PP in thrombus endothelial cells may represent one mechanism utilized in this disease to shift the local hemostatic balance and preserve regional vessel patency.