Biomedical subjects

Tal Geva

Publications and source records attributed to Tal Geva.

43 records · Page 3Linked to original sources

PubMed2002

Gadolinium-enhanced three-dimensional magnetic resonance angiography of pulmonary and systemic venous anomalies.

OBJECTIVE: The goal of this study was to evaluate the diagnostic value of gadolinium (Gd)-enhanced three-dimensional (3D) magnetic resonance angiography (MRA) in patients with congenital and acquired anomalies of the pulmonary and systemic veins. BACKGROUND: Gadolinium-enhanced 3D MRA is a fast magnetic resonance imaging technique that has shown great promise in the evaluation of large and medium-sized arteries. However, its application to venous anomalies has not been studied in detail. METHODS: The study retrospectively analyzed all patients who underwent Gd-enhanced 3D MRA examination from January 1998 through January 2001, were diagnosed with anomalies of the pulmonary or systemic veins and had additional diagnostic data available for comparison with the MRA findings. RESULTS: Sixty-one patients (age 1 day to 60 years) were included. Image acquisition was completed in 29 +/- 6.9 s. Pulmonary venous anomalies were found in 37 patients, systemic venous anomalies in 17 patients and both pulmonary and systemic venous anomalies in 7 patients. Compared with available diagnostic information by other modalities, all known or suspected venous anomalies were imaged by 3D MRA. In three patients, catheterization did not detect anomalies of the pulmonary veins that were subsequently diagnosed by MRA. The 3D MRA diagnoses were followed by 10 interventional catheterization procedures and 15 operations. In 74% of patients, 3D MRA either diagnosed previously unsuspected venous anomalies (28%) or added new clinically important information (46%). The mechanism of pulmonary vein compression in eight patients was determined by MRA but not by other imaging modalities. Using a five-level grading system for MRA image quality (1 = nondiagnostic; 5 = excellent), the average grade was 4.6 +/- 0.6, with a 0.28 +/- 0.6 mean grade difference between two independent observers. CONCLUSIONS: Gadolinium-enhanced 3D MRA is capable of rapidly and accurately diagnosing a wide spectrum of pulmonary and systemic venous anomalies and is a useful noninvasive alternative to diagnostic catheterization.

Adolescent↗

PubMed2002

Adaptive mechanisms of left ventricular diastolic function to the physiologic load of pregnancy.

BACKGROUND: Pregnancy is associated with marked alteration in cardiovascular hemodynamics. Recent reports have characterized the effects on cardiac systolic function. Little has been written on the influences of loading conditions on Doppler measures of diastolic function during pregnancy. HYPOTHESIS: Stage of pregnancy has an impact on Doppler indices of diastolic function independent of loading conditions, systolic function, and heart rate. METHOD: Thirty healthy women were prospectively evaluated by serial echocardiography and Doppler examinations at six time periods: 10-12, 18-20, 28-30, 36-38 weeks gestation, 2-4 and 12-14 weeks postpartum. The related effects on indices of diastolic function and its interaction with load, heart rate, mass, and systolic function were determined. RESULTS: Compared with the nonpregnant state, early (E) velocity increased (0.7+/-0.1-0.9+/-0.1 m/s, p = 0.0001), peaking at 18 weeks and returning to normal levels during late pregnancy. Atrial phase (A) velocity peaked at 18 weeks (0.48+/-0.12-0.60+/-0.13 m/s, p = 0.0001), remaining high throughout the rest of pregnancy. Consequently, the EWA ratio fell significantly during late pregnancy, from 1.9+/-0.4 to 1.4+/-0.3 (p = 0.02). In addition, mean acceleration was significantly increased in early pregnancy with a peak at 18 weeks (7.4+/-1.3 m/s2), returning to nonpregnant level at term (5.7+/-1.4 m/s2, p = 0.0001). Generalized estimating equation using multivariate regression analysis demonstrated that rising heart rate and stroke volume index had an independent effect on A velocity, and that contractility and preload had an independent effect on E velocity. Pregnancy itself had an independent influence on early filling, not explained by the other parameters. CONCLUSIONS: During normal pregnancy, there is a reversible shift in transmitral flow velocities from early to late filling with a decrease in acceleration, consistent with an increase in ventricular compliance. Changes in heart rate, preload, and contractility, as well as stage of pregnancy influence this alteration.

Adult↗

PubMed2002

Effect of acquisition parameters on the accuracy of velocity encoded cine magnetic resonance imaging blood flow measurements.

PURPOSE: To investigate the effect of acquisition parameters on the accuracy of 2D velocity encoded cine magnetic resonance imaging (VEC MRI) flow measurements. MATERIALS AND METHODS: Using a pulsatile flow phantom, through-plane flow measurements were performed on a flexible vessel made of polyvinyl alcohol cryogel (PVA), a material that mimics the MR signal and biomechanical properties of aortic tissue. RESULTS: Repeated VEC MRI flow measurements (N = 20) under baseline conditions yielded an error of 0.8 +/- 1.5%. Slice thickness, angle between flow and velocity encoding directions, spatial resolution, velocity encoding range, and radio frequency (RF) flip angles were varied over a clinically relevant range. Spatial resolution had the greatest impact on accuracy, with a 9% overestimation of flow at 16 pixels per vessel cross-section. CONCLUSION: VEC MRI proved to be an accurate and reproducible technique for pulsatile flow measurements over the range of acquisition parameters examined as long as sufficient spatial resolution was prescribed.

Analysis of Variance↗

PubMed2002

Apical ventricular septal defects: follow-up concerning anatomic and surgical considerations.

BACKGROUND: Apical ventricular septal defects (VSDs) are difficult to visualize and close transatrially. We described their distinctive anatomic features, which have seldom been documented angiocardiographically and pathologically, in order to develop an effective approach for their surgical management. METHODS: Fourteen postmortem cases, two explanted hearts, 9 successfully operated patients, and 1 unoperated living patient were included in this report. Angiocardiographic documentation of the apical VSD was available in 14 of 16 (87.5%) of the postmortem and transplanted cases, and in 6 of 10 (60%) of the living patients. Echocardiograms were available in 23 of all 26 cases (88%). RESULTS: Severe associated malformations were present in 14 of 16 (87%) of the pathologically documented cases. Large VSDs allowed extensive communication between the left ventricular and the right ventricular sinuses in 4 patients. In 12 of the pathologically documented cases and in the 10 living patients, the left ventricular apex communicated with the right ventricular apical infundibular recess. CONCLUSIONS: Extremely large apical VSDs with severe biventricular dysplasia and dysfunction may require cardiac transplantation. Large apical VSDs can be successfully closed through a small apical infundibulotomy. This approach, applicable even in small infants, can avoid pulmonary artery banding or left ventriculotomy.

Angiocardiography↗

PubMed2002

Repair of ventricular septal defect and left ventricular aneurysm following blunt chest trauma.

In children, even minor trauma to the chest can result in cardiac injury. We describe a case of a 13-year-old boy who received blunt chest trauma during a motorcycle accident. He was initially symptom-free but later complained of persistent chest pain and a murmur was noted. An anterior muscular ventricular septal defect was detected one day after the accident, and a left ventricular pseudo-aneurysm developed days later. Both were successfully repaired 3 weeks after the injury.

Accidents, Traffic↗

PubMed2002

Cardiac relocation and chest wall reconstruction after separation of thoracopagus conjoined twins with a single heart.

Separation of thoracopagus conjoined twins with a single heart and the twin reversed arterial perfusion sequence yielded a single surviving infant with a protuberant heart covered by ribs and soft tissue from the nonsurviving twin. At 13 months of age, the heart was relocated in the chest after caudal mobilization of the diaphragms. The protective tissue cage was removed and a normal chest contour established. This technique also may be useful in the treatment of thoracic ectopia cordis.

Adult↗

PubMed1996

Echocardiographic Evaluation of Common Atrioventricular Canal Defects: A Study of 206 Consecutive Patients.

An accurate echocardiographic evaluation of common atrioventricular canal (CAVC) requires in-depth knowledge of the wide spectrum of morphological and physiological variations in this group of anomalies. In order to evaluate the incidence and morphological distribution of AV canal defects in a large series of patients and to define a systematic approach to the echocardiographic examination, we reviewed the echocardiograms of 206 consecutive patients with CAVC studied at Texas Children's Hospital over a 32-month period. The complete form of CAVC was most common (68.4%) and presented at an earlier age (mean +/- SD: 1.6 +/- 2.4 months). A partial AV canal (ostium primum atrial septal defect [ASD]) was found in 42 patients (20.4%) and their age at presentation was higher (9.2 +/- 10 months). Twenty-three patients (11.2%) had a transitional AV canal. Down syndrome was diagnosed in 34% of patients, the majority of whom (79%) had a complete CAVC. Associated malformations were found in 46% of patients: anomalies of the conotruncus were most frequent (18%), followed by secundum ASD (14.1%), anomalous pulmonary venous connection (11.2%), and heterotaxy syndrome (11.2%). Subaortic obstruction and mitral stenosis were less common. The AV canal was unbalanced in 14.1% of patients, with the right ventricular dominant form being more common than the left ventricular dominant form (10.7% and 3.4%, respectively). Based on our experience, we developed a systematic, segment-by-segment approach to the echocardiographic examination in infants with CAVC. Together with detailed anatomical information, Doppler evaluation provides crucial hemodynamic information that allows planning of surgical repair. (ECHOCARDIOGRAPHY, Volume 13, July 1996)

Journal Article↗