A quantitative procedure to probe for compositional inhomogeneities in InxGa1-xN alloys.

The distribution of indium in a GaN/InxGa1-xN/AlyGa1-yN quantum well with x+/-Deltax=0.24+/-0.07 is quantitatively investigated by extraction of displacement fields from lattice images. Simulations accurately describe the measured strain relaxation across a wedge-shaped sample for a sample thickness up to 150nm. The proportionality between indium concentration and resulting lattice constant cx is approximated by cx=0.5185+0.111xnm. In general, it is challenging to discriminate the effects of random alloying against clustering. In InxGa1-xN this is particularly true at low indium concentrations x<0.2. For an accurate quantitative analysis, sample preparation and imaging were developed such that radiation damage can be recognized if present. Further, an analysis of detection limits and knowledge of the sample thickness are crucial for obtaining reproducible results. Data averaging is necessary to reach sufficient precision. Consequently, the size of the indium-rich clusters is poorly known if x is small. Beyond the interest in physical properties of InxGa1-xN alloys, the analysis of strain and its relaxation exemplifies how quantitative analysis is possible at an atomic level and is in excellent agreement with theoretical predictions.

Primary ovarian carcinoid heart disease curatively treated with a two-stage procedure.

Primary ovarian carcinoid disease with cardiac involvement is a very rare syndrome, which requires interdisciplinary management. We report on a patient with primary ovarian carcinoid tumor with severe tricuspid valve insufficiency who was curatively treated after successful tumor resection and tricuspid valve replacement.

Generation of single-cycle THz transients with high electric-field amplitudes.

Single-cycle terahertz (THz) transients in the frequency range 0.3-7 THz with electric-field amplitudes of more than 400 kV/cm are generated by four-wave mixing of the fundamental and the second harmonic of 25 fs pulses from a Ti:sapphire amplifier in ionized air. These transients are fully characterized by electro-optic sampling with ZnTe and GaP crystals. One can tune the center frequency of the THz transients by varying the length of the incident pulse. The electric-field amplitude increases linearly with the incident pulse energy.

Resistant hypertension in patients with chronic aortic dissection.

Strict blood pressure control is pivotal in the management of patients with aortic dissection (AD), but is frequently difficult to achieve. We determined antihypertensive medical therapy and levels of blood pressure (BP) control in 40 patients with chronic AD. Patient charts were reviewed for clinical variables, serial BP measurements, and antihypertensive drug therapy. Patients were divided into two groups: patients in group 1 had effective BP control (<135/80 mmHg), patients in group 2 had resistant hypertension (BP>/=135/80 mmHg despite prescription of at least three antihypertensive drugs). Overall, systolic BP (SBP) was 130+/-20 mmHg, and diastolic BP (DBP) was 72+/-13 mmHg. Patients received a median of 4 (1-6) antihypertensive drugs. beta-blockers were used in 38/40 (95%) patients. Effective BP control was achieved in 24/40 (60%) patients (group 1), while 16/40 (40%) patients had resistant hypertension (group 2) despite receiving significantly more antihypertensive drugs (5 [4-6] vs 4 [1-5], P=0.001). Mean SBP was 116+/-9 (101-132) mmHg in group 1 and 151+/-13 (137-181) mmHg in group 2 (P<0.001); there was no difference in DBP. Group 2 patients had a significantly higher body mass index and were younger than patients in group 1. In conclusion, in the majority of patients with chronic AD, effective BP control can be achieved, but usually requires the combination of multiple antihypertensive drugs. However, in a significant proportion of patients (40%), who appear to be younger and more obese, medical therapy fails to achieve effective BP control despite use of a multiple drug regimen.

Acute and long-term outcome after coronary artery perforation during percutaneous coronary interventions.

BACKGROUND: Coronary artery perforation is a rare but serious complication of percutaneous coronary interventions (PCI). METHODS: We reviewed our database for cases of overt coronary perforation during PCI procedures. Hospital charts, procedural reports, and coronary angiograms of these patients were reviewed, with particular emphasis on mechanisms of perforation, management of the complication, and clinical outcome. RESULTS: Between 01/1998 and 12/2003, a total of 19 cases (mean age: 66+/-8 years, 13 male) of coronary perforation occurred during 6433 PCI procedures performed within this period (incidence: 0.3%). In 12/19 (63%) cases, perforation occurred during recanalisation procedures of chronic total occlusions of coronary arteries. In all but one patient, non-surgical management was attempted: 2 out of 19 (11%) patients were treated conservatively by reversal of heparin anticoagulation. Prolonged balloon inflation at the perforation site was applied in 10/19 (53%) patients. Six (32%) patients received stents (5 of them received covered stentgrafts), 3 (16%) patients developed cardiac tamponade requiring percardiocentesis, and only 2 (11%) patients underwent bailout surgical repair. There were 2 (11%) deaths early after the procedure. CONCLUSION: Coronary perforation during PCI is a rare complication, but is associated with significant morbidity and mortality. In the majority of patients, non-surgical management is both feasible and associated with a high success-rate.

Severe left ventricular failure after double lung transplantation: pathophysiology and management.

Patients undergoing bilateral lung transplantation for end-stage pulmonary hypertension may experience various complications. We describe a patient who underwent transplantation for chronic pigeon breeder's disease, who had secondary pulmonary hypertension and deteriorated right heart function, and who developed severe left heart failure during the weaning phase after successful double lung transplantation. The patient was stabilized with catecholamines and an intra-aortic balloon pump. Left heart function increased within 7 days and normalized at Day 18. Otherwise, the post-operative course was uneventful.

Tei-Index in coronary artery disease--validation in patients with overall cardiac and isolated diastolic dysfunction.

BACKGROUND: The index "isovolumic contraction time and isovolumic relaxation time divided by ejection time" ("Tei-Index") has been demonstrated to provide useful information about disease severity and prognosis in patients with dilated cardiomyopathy and cardiac amyloidosis. In patients with coronary artery disease (CAD), the diagnostic utility of this index is unclear. We attempted to validate the Tei-Index in CAD patients with overall cardiac or isolated diastolic dysfunction. METHODS AND RESULTS: Sixty subjects were included who underwent left heart catheterization for invasive measurement of left ventricular end-diastolic pressure (LVEDP): 20 symptomatic CAD patients with overall cardiac dysfunction (defined by a LV ejection fraction (EF) < 45% (mean 27 +/- 8%) and a LVEDP > or = 16 mmHg, (mean 22 +/- 6 mmHg), NYHA class 2.7 +/- 0.4, OCD group), 29 symptomatic CAD patients with isolated diastolic dysfunction (defined by an EF > 45% (mean 55 +/- 8%), a normal end-diastolic diameter index (mean 2.8 +/- 0.4 cm/m2) and a LVEDP > or = 16 mmHg (mean 22 +/- 6 mmHg), NYHA class 2.3 +/- 0.4, IDD group) and 11 asymptomatic control subjects (EF 65 +/- 9%, LVEDP 11 +/- 4 mmHg, CON group). After conventional 2-D- and Doppler echocardiographic examination, the Tei-Index was obtained. The Tei-Index was easily and reproducibly measured in all study subjects. In the OCD group, isovolumic contraction time was prolonged and ejection time was shortened in comparison to the CON group, resulting in a significantly increased Tei-Index (0.71 +/- 0.28 vs 0.40 +/- 0.11, p < 0.01). In the IDD group, isovolumic relaxation time was prolonged and isovolumic contraction time was shortened in comparison to controls, resulting in a largely unchanged Tei-Index (0.45 +/- 0.14, p = ns). Receiver operating characteristic curve analysis for the Tei-Index yielded an area under the curve of 0.92 +/- 0.04 for separating patients with vs without OCD. Using a Tei-Index > 0.49 as a cut-off, OCD patients were identified with a sensitivity of 96% and a specificity of 86%. CONCLUSION: The Tei-Index is a valid and readily derived indicator of global cardiac dysfunction in CAD patients with impaired systolic and diastolic LV performance. The use of this index seems to be limited in CAD patients with primary diastolic dysfunction.

Acromegaly: evidence for a direct relation between disease activity and cardiac dysfunction in patients without ventricular hypertrophy.

BACKGROUND AND AIMS: Cardiac abnormalities, such as cardiomegaly and congestive heart failure, occur frequently in advanced acromegaly. Abnormalities of systolic and diastolic function, mostly associated with left ventricular (LV) hypertrophy, have been reported. The impact of disease activity on LV performance in patients with normal or slightly elevated LV muscle mass has not been demonstrated. PATIENTS AND METHODS: Conventional two-dimensional/Doppler echocardiography and tissue Doppler imaging (TDI) of the mitral annulus were performed in 13 patients with active acromegaly (AA) and normal or slightly elevated LV muscle mass (< 140 g/m2) and in 19 cured/well-controlled patients (CA). A group of 21 volunteers without symptoms or signs of cardiac disease served as controls (CON). The combined myocardial performance index (Tei-Index) was determined in all patients and controls. RESULTS: Muscle mass index of the left ventricle, ejection fraction, fractional shorting, E/ET-ratio, systolic (ST) and late diastolic (AT) annular velocities did not differ significantly between the three groups. In the AA group, the early diastolic annular velocity ET[7.13 +/- 2.11 (AA); 9.83 +/- 3.29 (CA); 10.10 +/- 1.70 m/s (CON); P < 0.05 AA vs. CA, P < 0.005 AA vs. CON] and the ET/AT-ratio [0.71 +/- 0.26 (AA); 0.95 +/- 0.33 (CA); 1.00 +/- 0.15 m/s (CON); P < 0.05 AA vs. CA, P < 0.005 AA vs. CON] were significantly reduced. Patients with AA had a longer deceleration time [209 +/- 19 (AA); 179 +/- 22 (CA); 185 +/- 26 ms (CON); P < 0.05]. The Tei-Index was significantly higher in AA in comparison with CON [0.50 +/- 0.15 (AA); 0.48 +/- 0.12 (CA); 0.41 +/- 0.10 (CON); P < 0.05 AA vs. CON]. Subjects with CA did not differ significantly from controls with respect to 2-D/Doppler echo- and TDI-derived parameters. CONCLUSION: The data demonstrate that diastolic dysfunction can be verified by tissue Doppler imaging in patients with active acromegaly with normal or slightly elevated muscle mass of the left ventricle and seems to be related to disease activity. The Tei-Index as a sensitive combined myocardial performance index can be used to complete the assessment of systolic and diastolic LV performance in acromegalic patients.

Paracardial lipodystrophy versus pericardial effusion in HIV positive patients.

OBJECTIVE: To present an epicardial manifestation of the lipodystrophy syndrome, a side effect of antiretroviral treatment in HIV positive patients, which illustrates the important danger of false diagnosis. PATIENT: A 52 year old man with HIV (stage C3), diagnosed 10 years previously, was being treated with a combination of nelfinavir, nevirapine, and stavudine. Echocardiographic examination showed a low echogenic pericardial space that had increased from 4 mm to 18 mm over a 10 month period. The diagnosis of paracardial adipose tissue was verified by magnetic resonance tomography. Doppler echocardiographic parameters were not significantly altered (ratio of early to late ventricular filling 0.88 v 0.73, Tei index 0.30 v 0.36). CONCLUSION: Even a pericardial manifestation of lipodystrophy causes negligible functional impairment, misinterpretation of the lipodystrophy as a pericardial effusion and a subsequent puncture can have serious complications. Hence, it is strongly suggested that further differential diagnosis be used for HIV positive patients with an echocardiographic suspicion of pericardial effusion. Differential diagnosis by magnetic resonance tomography is possible.

[Diagnosis of endocarditis today: Duke criteria or clinical judgment?]. / Endokarditisdiagnostik heute: Duke-Kriterien oder klinische Einschätzung?

DIAGNOSIS OF INFECTIVE ENDOCARDITIS: Due to the complexity of the clinical diagnosis of infective endocarditis, standardized diagnostic schemes have been developed to improve the sensitivity and specificity of the diagnosis. The Von Reyn criteria, introduced in 1981 relied mainly on clinical, microbiological, and histopathological criteria and were for more than 10 years regarded as the diagnostic goldstandard. However, the Von Reyn criteria have a sensitivity of merely about 30-60% and their reliability is especially low in case of negative blood cultures. ROLE OF ECHOCARDIOGRAPHY: An important step towards an improved sensitivity and specificity in the diagnosis of infective endocarditis was the introduction of transesophageal echocardiography, which is far more sensitive and specific in this indication than the transthoracic approach. Besides the early detection of vegetations and complications such as abscess formation, valvular destructions or perforations, echocardiography may be helpful to identify patients at risk for a prolonged healing, embolization, or may be also used to monitor the therapeutic progress. THE DUKE CRITERIA: Implementation of echocardiography into the Duke criteria, introduced in 1994, yielded as expected, a significant higher sensitivity of up to 100% than the von Reyn criteria with an almost identical specificity. Thus, the latter were completely replaced by the Duke criteria in clinical practice. MODIFICATIONS OF THE DUKE CRITERIA: Nevertheless, some uncertainty remains, especially in culture-negative endocarditis which has led to certain modifications of the Duke criteria. Besides the implementation of unspecific inflammatory parameters such as the C-reactive protein, a positive Q-fever serology has been added and any S. aureus bacteremia is now judged as major criterion. Although a prospective evaluation has to be awaited, these modifications appear promising and should be implemented into clinical practice. CONCLUSIONS: The Duke criteria are currently the most sensitive tool in the diagnosis of infective endocarditis. It can be expected that they will help to significantly shorten the time to diagnosis, and may, thus, improve the clinical outcome.

Changes in QRS voltage in cardiac tamponade and pericardial effusion: reversibility after pericardiocentesis and after anti-inflammatory drug treatment.

OBJECTIVES: The goal of this study was to define the association between low QRS voltage and cardiac tamponade or pericardial effusion and to assess the reversibility of low QRS voltage after therapeutic procedures. BACKGROUND: It is unclear whether low QRS voltage is a sign of cardiac tamponade or whether it is a sign of pericardial effusion per se. METHODS: In a prospective study design, we recorded consecutive 12-lead electrocardiograms and echocardiograms in 43 patients who were referred to our institution for evaluation and therapy of a significant pericardial effusion. Cardiac tamponade was present in 23 patients (53%). Low QRS voltage (defined as maximum QRS amplitude <0.5 mV in the limb leads) was found in 14 of these 23 subjects (61%). Nine of these 14 patients were treated by pericardiocentesis (group A). Five patients received anti-inflammatory medication (group B). Group C consisted of nine patients with pericarditis and significant pericardial effusion who had no clinical evidence of tamponade. RESULTS: In group A, low QRS voltage remained largely unchanged immediately after successful pericardiocentesis (0.36 +/- 0.17 mV before vs. 0.42 +/- 0.21 mV after, p = NS), but QRS amplitude recovered within a week (0.78 +/- 0.33 mV, p < 0.001). In group B, the maximum QRS amplitude increased from 0.40 +/- 0.20 mV to 0.80 +/- 0.36 mV (p < 0.001) within six days. In group C, all patients had a normal QRS amplitude initially (1.09 +/- 0.55 mV) and during a seven-day follow-up (1.10 +/- 0.56 mV, p = NS). CONCLUSIONS: Low QRS voltage is a feature of cardiac tamponade but not of pericardial effusion per se. Our findings indicate that the presence and severity of cardiac tamponade, in addition to inflammatory mechanisms, may contribute to the development of low QRS voltage in patients with large pericardial effusions.

Rapid progression of bacterial aortitis to an ascending aortic mycotic aneurysm documented by transesophageal echocardiography.

A case of bacterial aortitis of the ascending aorta caused by Staphylococcus aureus progressed to an aortic mycotic aneurysm. Transesophageal echocardiography was the diagnostic approach of choice. The different stages of the disease from the initial aortic wall infection to formation of an abscess that communicated with the aortic lumen were documented by transesophageal echocardiography.

Echocardiographic detection of coronary artery fistula into the pulmonary artery.

A rare case of left coronary artery--pulmonary artery fistula is reported. Transoesophageal echocardiography was capable of precisely demonstrating the origin, the course and the drainage site of the fistula. In contrast, transthoracic echocardiography could visualise a drainage flow in the pulmonary artery only. In conclusion, transoesophageal echocardiography may be helpful in the diagnosis or exclusion of the form of coronary artery fistula.

Full performance of modern echocardiography within the heart: in-vivo feasibility study with a new intracardiac, phased-array ultrasound-tipped catheter.

BACKGROUND: Intracardiac echocardiography with full performance of high-resolution two-dimensional-, M-mode-, colour, pulsed and continuous wave Doppler and Doppler tissue imaging has not been previously demonstrated. AIMS: This first European in-vivo study was designed to determine the utility and feasibility of a new ultrasound-tipped catheter for intravascular and intracardiac echocardiography. METHODS: The miniaturized, multi-modal, multiple-frequency (5-10MHz) transducer tipped 10Fr (3.3mm) catheter was tested in five anaesthetized mongrel dogs linked to a standard echocardiographic platform. The catheter was introduced through an 11 Fr femoral venous sheath into the inferior vena cava and right heart chambers and the pulmonary artery under limited fluoroscopic and catheter ultrasound guidance. RESULTS: Abdominal and thoracic aorta as well as their branches, both ventricles and atrias with their appendices, all valves, pulmonary arteries and all veins could be visualized with excellent quality. All Doppler signals and the determined haemodynamics, global and regional wall motion and Doppler tissue imaging were of high diagnostic quality. Coronary flow reserve could also be determined. CONCLUSIONS: Intracardiac echocardiography is feasible and potentially useful for assessing functional and morphological disorders, and probably for the guidance of interventional procedures as well as monitoring of cardiac function. A new window to the heart has been opened.

Nonsurgical retrieval of embolized coronary stents.

Embolization of coronary stents before deployment is a rare but challenging complication of coronary stenting. Different methods for nonsurgical stent retrieval have been suggested. There were 20 cases (0.90%) of intracoronary stent embolization among 2,211 patients who underwent implantation of 4,066 stents. Twelve of 1,147 manually crimped stents (1.04%) and eight of 2,919 premounted stents were lost (0.27%, P < 0.01) during retraction of the delivery system, because the target lesion could not be either reached or crossed. Percutaneous retrieval was successfully carried out in 10 of 14 patients (71%) in whom retrieval was attempted. In 10 patients, stent retrieval was tried with 1.5-mm low-profile angioplasty balloon catheters (success in 7/10) and in seven cases with myocardial biopsy forceps or a gooseneck snare (success in 3/7). Three patients (15%) underwent urgent coronary artery bypass surgery after failed percutaneous retrieval, but their outcomes were fatal. In two patients, stents were compressed against the vessel wall by another stent, without compromising coronary blood flow. In two patients, a stent was lost to the periphery without clinical side effects; treatment was conservative in these cases. Embolization of stents before deployment is a rare but serious complication of coronary stenting, with hazardous potential for the patient. Manual mounting of stents is associated with a significantly higher risk of stent embolization. Stent retrieval from the coronary circulation with low-profile angioplasty balloon catheters is a readily available and technically familiar approach that has a relatively high success rate.