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Biomedical subjects

H Omran

Publications and source records attributed to H Omran.

At least 55 records · Page 3Linked to original sources
PubMed1999

Transverse conduction capabilities of the crista terminalis in patients with atrial flutter and atrial fibrillation.

OBJECTIVES: In this study, the transverse conduction capabilities of the crista terminalis (CT) were determined during pacing in sinus rhythm in patients with atrial flutter and atrial fibrillation. BACKGROUND: It has been demonstrated that the CT is a barrier to transverse conduction during typical atrial flutter. Mapping studies in animal models provide evidence that this is functional. The influence of transverse conduction capabilities of the CT on the development of atrial flutter remains unclear. METHODS: The CT was identified by intracardiac echocardiography. The atrial activation at the CT was determined during programmed stimulation with one extrastimulus at five pacing sites anteriorly to the CT in 10 patients with atrial flutter and 10 patients with atrial fibrillation before and after intravenous administration of 2 mg/kg disopyramide. Subsequently, atrial arrhythmias were reinduced. RESULTS: At baseline, pacing with longer coupling intervals resulted in a transverse pulse propagation across the CT. During shorter coupling intervals, split electrograms and a marked alteration of the activation sequence of its second component were found, indicating a functional conduction block. In patients with atrial flutter, the longest coupling interval that resulted in a complete transverse conduction block at the CT was significantly longer than that in patients with atrial fibrillation (285 +/- 49 ms vs. 221 +/- 28 ms; p < 0.05). After disopyramide administration, a transverse conduction block occurred at longer coupling intervals as compared with baseline (287 +/- 68 ms vs. 250 +/- 52 ms; p < 0.05). Subsequently, a sustained atrial arrhythmia was inducible in 15 of 20 patients. This was atrial flutter in three patients with previously documented atrial fibrillation and in eight patients with history of atrial flutter. Mapping revealed a conduction block at the CT in all of these patients. CONCLUSIONS: It was found that the CT provides transverse conduction capabilities and that the conduction block during atrial flutter is functional. Limited transverse conduction capabilities of the CT seem to contribute to the development of atrial flutter.

Aged↗
PubMed1999

Exclusion of the candidate genes ACE and Bcl-2 for six families with nephronophthisis not linked to the NPH1 locus.

BACKGROUND: Nephronophthisis (NPH) is an autosomal recessively transmitted kidney disease, characterized by cyst formation at the cortico-medullary junction, and a sclerosing tubulointerstitial nephropathy. Juvenile nephronophthisis (NPH1) is the most common genetic cause of renal failure in children and maps to chromosome 2q12-q13. The responsible gene NPHP1 has been identified and encodes for nephrocystin. Not all families with NPH demonstrate linkage to that locus. METHODS: We studied six families with NPH without linkage to the NPH1 locus. In order to attempt identification of a new causative gene, the candidate genes ACE (angiotensin converting enzyme) and Bcl-2 (B cell leukaemia/lymphoma 2 gene) originating from mouse models, were examined. For the six families highly polymorphic microsatellites covering the whole candidate gene regions were haplotyped and linkage analysis was performed. RESULTS: Haplotype analyses of all families examined were incompatible with linkage of the disease status to ACE or Bcl-2. Linkage analysis excluded both candidate gene regions with a LOD-score of < -2. CONCLUSIONS: This study excluded the candidate genes ACE and Bcl-2 for NPH. Additional linkage studies need to be performed in order to identify further genes responsible for nephronophthisis.

Adolescent↗
PubMed1999

Imaging of thrombi and assessment of left atrial appendage function: a prospective study comparing transthoracic and transoesophageal echocardiography.

OBJECTIVE: To compare the value of current transthoracic echocardiographic systems and transoesophageal echocardiography for assessing left atrial appendage function and imaging thrombi. DESIGN: Single blind prospective study. Patients were first investigated by transthoracic echocardiography and thereafter by a second investigator using transoesophageal echocardiography. The feasibility of imaging the left atrial appendage, recording its velocities, and identifying thrombi within the appendage were determined by both methods. PATIENTS: 117 consecutive patients with a stroke or transient neurological deficit. SETTING: Tertiary cardiac and neurological care centre. RESULTS: Imaging of the complete appendage was feasible in 75% of the patients by transthoracic echocardiography and in 95% by transoesophageal echocardiography. Both methods were concordant for the detection of thrombi in 10 cases. Transoesophageal echocardiography revealed two additional thrombi. In one of these patients, transthoracic echocardiography was not feasible and in the other the thrombus had been missed by transthoracic examination. In patients with adequate transthoracic echogenicity, the specificity and sensitivity of detecting left atrial appendage thrombi were 100% and 91%, respectively. Recording of left atrial appendage velocities by transthoracic echocardiography was feasible in 69% of cases. None of the patients with a velocity > 0.3 m/s had left atrial appendage thrombi. In the one patient in whom transthoracic echocardiographic evaluation missed a left atrial appendage thrombus, the peak emptying velocity of the left atrial appendage was 0.25 m/s. CONCLUSIONS: A new generation echocardiographic system allows for the transthoracic detection of left atrial appendage thrombi and accurate determination of left atrial appendage function in most patients with a neurological deficit.

Adult↗
PubMed1998

Echocardiographic parameters for predicting maintenance of sinus rhythm after internal atrial defibrillation.

Chronic atrial fibrillation (AF), which is refractory to external electrical direct current shock and/or pharmacologic cardioversion, may be successfully cardioverted using internal atrial defibrillation. To avoid unnecessary procedures, it is important to be able to predict which patients will revert to AF. Thirty-eight patients with chronic AF underwent successful internal atrial defibrillation and were followed for 6 months after restoration of sinus rhythm. Left atrial (LA) diameter, left ventricular ejection fraction, maximum LA appendage area, and peak emptying velocities of the LA appendage were analyzed to determine which of these factors were associated with recurrence of AF. Forty-nine percent of patients had a recurrence of AF within 6 months following internal atrial defibrillation. The preprocedural ejection fraction (mean +/- SD 59 + 14% vs 57 + 13%, p = 0.63), LA diameter (4.2 +/- 0.6 cm vs 4.5 +/- 0.6 cm, p = 0.16), and LA appendage area (5.0 +/- 1.5 cm2 vs 5.8 +/- 1.5 cm2, p = 0.13) did not differ significantly between patients who maintained sinus rhythm and those who had recurrence of AF. Peak emptying velocities of the LA appendage before cardioversion were significantly lower in patients with recurrence of AF compared with patients who maintained sinus rhythm (0.26 +/- 0.1 m/s vs 0.49 +/- 0.17 m/s, p = 0.001). A peak emptying velocity <0.36 had a sensitivity of 82% and a specificity of 83% for predicting recurrence of AF.

Aged↗
PubMed1998

[Circadian and weekly distribution of malignant ventricular arrhythmias in patients with coronary heart disease or dilatative cardiomyopathy who have an implanted cardioverter-defibrillator].

BACKGROUND AND OBJECTIVE: Epidemiological studies have demonstrated a circadian distribution of sudden cardiac death (SD) and acute myocardial infarction (AMI), with a maximum frequency of events during the morning hours. Recently an analysis of computer recordings of implanted cardioverter/defibrillators has confirmed these findings with respect to SD. The majority of these studies concerned patients with coronary heart disease. In a prospective study we evaluated the circadian and weekly distribution of malignant ventricular tachyarrhythmias (VTA) in patients with a nonischaemic cardiac disease, namely dilated cardiomyopathy (CMP), and those with coronary heart disease (CHD). PATIENTS AND METHODS: Over a mean period of 25 +/- 9 months computer-stored data and cardiac electrograms recorded from the implanted cardioverter/defibrillators (ICD) were analysed in 28 patients with CHD and 11 with DCMP. The circadian and weekly distribution of VTA was obtained, using customary arrhythmia classification and the stored and timed events. RESULTS: Patients with CHD had a maximal frequency of VTA or ventricular fibrillation (VF) during the morning, with a peak between 9 and 10 o/c, while those with DCMP were at a higher risk of VTA or VF in the later afternoon and early evening. Regarding the frequency of events during the week, a significantly higher incidence of VTA was recorded on Saturdays in those with CHD, but on Mondays and Wednesdays in those with DCMP. INTERPRETATION: The circadian and weekly distribution of VTA differs significantly between patients with CHD and those with DCMP. A possible reason for this difference may be different trigger mechanisms in the two types of cardiac disease, since transient ischaemia is unlikely to be the cause in patients with nonischaemic DCMP.

Cardiomyopathy, Dilated↗
PubMed1998

[Löffler fibroblastic endocarditis in the thrombotic stages in isolated right ventricular tissue eosinophilia].

We report on a male, 31 year old, Turkish patient with an intracardiac mass in the right ventricle, reduction of performance and weight, as well as intermittent fever. No eosinophilia was documented in the peripheral blood; cardiac function was primarily normal. Besides the differential diagnosis of Löffer's endocarditis (endomyocardial fibrosis) an inflammatory disease and a malignant cardiac tumor were suggested. The diagnosis of Löffler's endocarditis could not be confirmed morphologically by echocardiography nor histologically by right ventricular biopsy. Operative removal of the mass lesion was necessary because of fast tumor progression, fulminant pulmonary embolism, and infiltration of the tricuspid valve. Only then, histologically Löffler's eosinophilic endocarditis of thrombotic stage was diagnosed. Antiphlogistic therapy with cortisone was initially performed. With a dose reduction after 6 months, a relapse of the thrombotic mass occurred. Therefore, continuous treatment with cortisone and azathioprine was induced followed by further tumor regression and further clinical stabilization since 8 months of treatment.

Adult↗
PubMed1998

Two novel mutations of the gene for Kir 1.1 (ROMK) in neonatal Bartter syndrome.

Bartter syndrome, an autosomal recessive renal tubular disorder, is associated with hypokalemic metabolic alkalosis with high renin and aldosterone plasma concentrations with low or normal blood pressure and renal salt loss. Two genes, the gene encoding the furosemide-sensitive apical Na-K-2Cl cotransporter (NKCC2) and the gene encoding the luminal inwardly-rectifying potassium channel Kir 1.1 (ROMK), have been reported to cause the neonatal subtype of Bartter syndrome. In a patient with neonatal Bartter syndrome, we report two novel mutations resulting in amino acid exchanges Ala156Val and Leu220Phe in the gene for Kir 1.1 that have been identified by single-strand conformation polymorphism analysis and subsequent direct sequencing. Both mutations occur in functional relevant domains of the channel protein and are therefore highly suggestive of altering channel properties.

Adult↗
PubMed1998

Prospective evaluation of the quality and long-term stability of atrial signals in non-thoracotomy defibrillation electrodes: comparison of four different endocardial electrograms.

UNLABELLED: Documentation of atrial signals in stored endocardial electrograms of modern implantable cardioverter-defibrillators (ICD) is a useful tool to classify the underlying arrhythmia leading to device therapy. Newest generations of ICD provide near- and far-field electrograms derived between various endocardial electrodes. The aim of this prospective study was to assess the quality and long-term stability of atrial signals in different far-field configurations including the active can housing. METHODS AND RESULTS: A total of 300 real-time endocardial electrogram recordings in 60 consecutive patients with a modern ICD in subpectoral position were analysed at the time of implant, pre-hospital discharge, 1, 3 and 12 months follow-up. Four different configurations were evaluated: right ventricular coil to can housing, can housing to pace/sense ring, right ventricular coil to pace/sense tip, and pace/sense tip to pace/sense ring. The best visibility of p-waves at an ECG-resolution of 0.5 mV/mm was seen in the can to coil configuration (77% of the patients). In the can to pace/sense ring electrogram p-waves could be observed in 58% of the patients. No p-waves were visible to pace/sense tip to pace/sense ring. At a resolution of 1.0 mV/mm p-waves were only visible in 10% of all patients exclusively in the can housing to right ventricular coil configuration. The results were stable (100% of the patients) over a follow-up of one year. CONCLUSIONS: Endocardial far-field electrograms, derived from the can housing and the right ventricular coil provide a p-wave visibility in 77% of the patients and demonstrate a long-term stability over at least one year, provided that the ECG-resolution is set at 0.5 mV/mm. Since the electrogram resolution of stored electrograms depends on the EGM-range, and the ECG-resolution at an EGM-range of 15 mV would be 1 mV/mm, the EGM-range is recommended to be programmed to 7.5 mV to ensure an ECG-resolution of at least 0.5 mV/mm for stored electrograms.

Algorithms↗
PubMed1998

Transvasal closure of interatrial defects using the Babic double-umbrella occluder system.

The purpose of the study was to assess the feasibility and safety of closure of atrial septal defects and patent foramen ovale by means of a new interventional technique. Transvasal closure of ostium secundum atrial septal defect and patent foramen ovale was performed in 18 patients using an occluder system for atrial septal defects. Two patients had undergone unsuccessful direct surgical closure years before. Implantation and follow-up were controlled using radiographic views both with and without contrast injection, transthoracic and multiplane transesophageal echocardiographic imaging, color Doppler sonography, and computed tomography. The defect was closed in 16 patients using 19 procedures. Removal of the devices through the sheath was indicated in 4 patients because of placement failure. Intraprocedural complications were ventricular fibrillation in one patient and fixation of the device in Chiari's network in an additional one. During 7-26 months follow-up occluder damage was seen in two patients and perforation of the left atrium in one patient. Thickening on the occluder surface was observed in two patients. There was no death. The system for closure of atrial septal defect is feasible and safe in patients with defects < or = 27 mm in diameter. Long-term observation of outcome is limited yet.

Adult↗
PubMed1998

Axonal neuropathy and predominance of type II myofibers in infantile spinal muscular atrophy.

Two affected siblings with infantile spinal muscular atrophy (SMA I) presented with generalized muscular hypotonia, which progressed to early death. Quadriceps muscle biopsy did not show the typical neurogenic pattern of spinal muscular atrophy. The histochemical fiber type determination revealed a predominance of type II fibers without type I hypertrophy, an unprecedented finding in spinal muscular atrophy. Sural nerve biopsy exhibited findings typical for axonal neuropathy. In one patient, electrical stimulation of peripheral nerves showed an inexcitability of motor and sensory nerves. Genetic studies revealed homozygous deletions of the telomeric survival motor neuron (SMN) gene and the neuronal apoptosis inhibitory protein (NAIP) gene in the affected children. This is the second case report of molecular genetically proven spinal muscular atrophy associated with axonal neuropathy. We conclude atypical findings on muscle biopsy and evidence of axonal neuropathy are compatible with the diagnosis of infantile spinal muscular atrophy.

Adult↗
PubMed1998

Left atrial appendage function after internal atrial defibrillation.

To determine the value of echocardiographic parameters for predicting maintenance of sinus rhythm after internal atrial defibrillation (IAD), transthoracic and transesophageal echocardiography were performed in 38 patients with atrial fibrillation (AF) before IAD. In addition, serial echocardiographic examinations were performed at 1, 7, and 28 days after IAD in 20 patients to assess the effect of IAD on echocardiographic markers of thromboembolic risk. AF had recurred in 49% of patients within 6 months following IAD. Left atrial chamber and appendage size and ejection fraction were not predictive of recurrence of atrial fibrillation. However, peak emptying velocities of the left atrial appendage were significantly lower in patients with recurrence of atrial fibrillation as compared with patients who had maintained sinus rhythm (0.26 +/- 0.1 m/sec vs 0.49 +/- 0.17 m/sec; P = 0.001). A peak emptying velocity < 0.36 m/sec had a sensitivity of 82% and specificity of 83% for predicting the recurrence of AF. Peak A wave velocities increased gradually after cardioversion from 0.47 +/- 0.16 m/sec at 24 hours to 0.61 +/- 0.13 m/sec after 7 days (P < 0.05). One patient developed a new thrombus in the left atrial appendage and another patient suffered a thromboembolic event after IAD. Assessment of left atrial appendage function adds information regarding the probability of maintaining sinus rhythm after the procedure and the need for anticoagulation therapy with IAD.

Anticoagulants↗
PubMed1998

Specific considerations with the automatic implantable atrial defibrillator.

INTRODUCTION: Internal atrial defibrillation has been evaluated as an alternative approach to the external technique for more than two decades. Previous studies in animals and humans have shown that internal atrial defibrillation is feasible with relatively low energies. The promising results achieved with internal atrial defibrillation have facilitated the development of an implantable atrial defibrillator (IAD). METHODS AND RESULTS: For any new therapy, it is imperative to demonstrate safety, efficacy, tolerability with improvement in quality of life, and cost-effectiveness compared with therapeutic options already available. Maintenance of sinus rhythm or prolonged duration in arrhythmia-free intervals should be demonstrated clearly with an IAD. Initial clinical experience with the Metrix system indicates stable atrial defibrillation thresholds, appropriate R wave synchronization markers, no shock-induced ventricular proarrhythmia, and excellent detection of atrial fibrillation (AF) with a specificity of 100%. Ventricular proarrhythmia has not been reported for correctly R wave synchronized low-energy shocks when closely coupled to RR intervals, and long-short cycles are avoided. CONCLUSION: Preliminary experience with the Metrix system suggests that the IAD may offer a therapeutic alternative for a subgroup of patients with drug-refractory, symptomatic, long-lasting, and infrequent episodes of AF. Further efforts must be undertaken to reduce the patient discomfort associated with internal atrial defibrillation in an attempt to make this new therapy acceptable to a larger patient population with AF.

Algorithms↗
PubMed1997

Probable Opitz trigonocephaly C syndrome with medulloblastoma.

We report on a patient with trigonocephaly, biparietal widening as a result of metopic synostosis, strabismus, upslanted palpebral fissures, apparently low-set ears with abnormal helices, deeply furrowed palate, postaxial polysyndactyly of the feet, ankle flexion deformities, cryptorchidism, loose skin, and severe mental retardation, findings compatible with a diagnosis of the Opitz trigonocephaly C syndrome (OTS). At the age of 12 years this patient presented with symptoms of raised intracranial pressure. A biopsy showed findings diagnostic of a medulloblastoma WHO Grade IV, an unprecedented finding in OTS. The possibility of coincidence should not prevent continued surveillance of OTS patients in the future for the occurrence of malignancy.

Abnormalities, Multiple↗
PubMed1997

[Septic myocardial aneurysm in mitral valve endocarditis. Clinical and pathological-anatomical findings].

HISTORY AND CLINICAL FINDINGS: A 68-year-old woman was hospitalized because of fever and tiredness for 3 months. Her general condition was clearly impaired. She had a mild fever of 38.5 degrees C and on auscultation a 3/6 systolic murmur, maximal parasternally in the 3rd intercostal space, transmitted to the apex. There were distant râles over both lungs, the neck veins were distended and there was ankle oedema. INVESTIGATIONS: C-reactive protein was raised to 17.3 mg/dl (normal up to 0.9 mg/dl), WBC count 19,300/microliter. beta-haemolysing streptococcus (S. agalactiae) was grown in the blood culture. The ECG showed sinus tachycardia (rate of 98/min) and transthoracic echocardiography demonstrated a small pericardial, enlarged ventricles, marked mitral regurgitation and a large vegetation on the posterior mitral leaflet, as well as a 3 x 4 cm mass in the posterior wall of the ventricle, originating from the posterior mitral valve ring and communicating with the vegetation on the mitral valve. The posterior mitral leaflet was perforated. TREATMENT AND COURSE: As endocarditis of the mitral valve with a complicated course was suspected-abscess of the posterior mitral valve ring and septic myocardial aneurysm with associated pericarditis and haemodynamically insignificant effusion-she was transferred to the intensive care unit where she died suddenly of circulatory arrest only 30 min after transfer. Autopsy confirmed the echocardiographic findings. CONCLUSION: Paravalvular abscess in the course of mitral valve endocarditis is rare, but should be looked for at transthoracic echocardiography so that any necessary surgical intervention can be undertaken early.

Aged↗