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Biomedical subjects

Gerald R Marx

Publications and source records attributed to Gerald R Marx.

14 recordsLinked to original sources
PubMed2006

One-stage neonatal corrective repair for d-transposition of the great arteries and complete atrio-ventricular canal.

Association of d-transposition of the great arteries and complete atrio-ventricular canal constitutes an uncommon and complex cardiac anomaly usually associated with poor prognosis. We report our experience on one-stage neonatal repair for d-transposition of the great arteries and complete atrio-ventricular canal. Between August 1997 and 2005, four patients (two males and two females) underwent anatomical correction for d-transposition of the great arteries and complete atrio-ventricular canal using an arterial switch procedure and two-patch repair. Mean age and weight at operation were 20 days (range from 3 to 28 days) and 3.2kg (range from 2.7 to 3.5kg), respectively. None of the patients received preoperative palliative procedure. Associated lesions were left outflow tract obstruction in three patients and multiple muscular ventricular septal defects in two patients. All four patients survived the operation. There was one in-hospitality death due to fungal sepsis. One patient required late re-operation for left ventricular outflow tract obstruction and left atrio-ventricular valve regurgitation. For a mean follow-up of 67 months (range from 51 to 90 months) all patients are asymptomatic and with no residual defects. Corrective repair of d-transposition of the great arteries and complete atrio-ventricular canal can be successfully achieved in this very challenging population during the neonatal period.

Abnormalities, Multiple↗
PubMed2006

Fetal aortic valve stenosis and the evolution of hypoplastic left heart syndrome: patient selection for fetal intervention.

BACKGROUND: Fetal aortic valvuloplasty may prevent progression of aortic stenosis (AS) to hypoplastic left heart syndrome (HLHS). Predicting which fetuses with AS will develop HLHS is essential to optimize patient selection for fetal intervention. The aim of this study was to define echocardiographic features associated with progression of midgestation fetal AS to HLHS. METHODS AND RESULTS: Fetal echocardiograms were reviewed from 43 fetuses diagnosed with AS and normal left ventricular (LV) length at < or =30 weeks' gestation. Of 23 live-born patients with available follow-up data, 17 had HLHS and 6 had a biventricular circulation. At the time of diagnosis, LV length, mitral valve, aortic valve, and ascending aortic diameter Z-scores did not differ between fetuses that ultimately developed HLHS and those that maintained a biventricular circulation postnatally. However, all of the fetuses that progressed to HLHS had retrograde flow in the transverse aortic arch (TAA), 88% had left-to-right flow across the foramen ovale, 91% had monophasic mitral inflow, and 94% had significant LV dysfunction. In contrast, all 6 fetuses with a biventricular circulation postnatally had antegrade flow in the TAA, biphasic mitral inflow, and normal LV function. With advancing gestation, growth arrest of left heart structures became evident in fetuses developing HLHS. CONCLUSIONS: In midgestation fetuses with AS and normal LV length, reversed flow in the TAA and foramen ovale, monophasic mitral inflow, and LV dysfunction are predictive of progression to HLHS. These physiological features may help refine patient selection for fetal intervention to prevent the progression of AS to HLHS.

Abortion, Therapeutic↗
PubMed2006

Three-dimensional echo and videocardioscopy-guided atrial septal defect closure.

BACKGROUND: Current real-time three-dimensional echocardiography systems (RT3DE) can provide sufficient visualization to permit atrial septal defect (ASD) closure. However, detailed visualization of small objects inside the heart is still suboptimal because of limited resolution, which is a limitation for clinical application. We evaluate the complementary use of videocardioscopy in image-guided ASD closure. METHODS: In a pig model (n = 5), a 4-mm to 8-mm ASD was created with RT3DE guidance. Defect closure was accomplished with a catheter-based patch-delivery system fixed around the defect with mini-anchors under combined RT3DE and videocardioscopy guidance. The endoscope was inserted into the heart through a custom built port designed to allow visualization in the presence of blood. RESULTS: All ASDs were successfully closed. The combination of RT3DE and videocardioscopy allowed detailed visualization of intracardiac structures, instruments, patch, and mini-anchors. CONCLUSIONS: Beating-heart ASD closure can be achieved with combined RT3DE and videocardioscopy imaging. Use of videocardioscopy provides high-resolution imaging and likely improves safety of the image-guided procedure.

Animals↗
PubMed2006

Determinants of left ventricular dysfunction after anatomic repair of congenitally corrected transposition of the great arteries.

BACKGROUND: Early results for anatomic repair of congenitally corrected transposition of the great arteries are excellent with respect to right ventricular and tricuspid valve function. However, development of left ventricular (systemic ventricle) dysfunction late after repair remains a concern. In this study we sought to determine factors leading to late impairment in left ventricular performance. METHODS: From August 1992 to July 2005, 44 patients (median age at surgery, 1.6 years; range, 0.6 to 39.6 years) with congenitally corrected transposition of the great arteries had anatomic repair. Left ventricular function and mitral regurgitation were evaluated by echocardiography at follow-up. Twenty-three patients had a Rastelli procedure, and 21 underwent an arterial switch. Twelve patients (27%) were pacemaker dependent at latest follow-up. RESULTS: Early mortality was 4.5% (n = 2) with 1 late death as a result of leukemia. Median follow-up was 3.0 years (range, 7 days to 12.4 years). Left ventricular function remained unchanged (normal) in 35 patients, improved in 1 patient, and deteriorated in 8 patients (18%). Mitral regurgitation was unchanged in 30 patients, improved in 6 patients, and worsened in 8 patients (18%). Development of left ventricular dysfunction was significantly associated with pacemaker implantation (p = 0.005) and a widened QRS (>20% > 98% percentile of normal; p = 0.03). CONCLUSIONS: Anatomic repair of congenitally corrected transposition can be performed with low operative mortality. However, late left ventricular dysfunction is not uncommon, with higher incidence in those requiring pacing and with a prolonged QRS. Resynchronization may be of value in patients requiring a pacemaker.

Adolescent↗
PubMed2005

Three-dimensional echo-guided beating heart surgery without cardiopulmonary bypass: atrial septal defect closure in a swine model.

OBJECTIVE: In this study, we tested 3 techniques of atrial septal defect closure under real-time 3-dimensional echocardiography guidance in a swine model. METHODS: The operations were conducted under the sole guidance of a modified real-time 3-dimensional echocardiography guidance system with a x4 matrix transducer (Sonos 7500, Philips Medical Systems, Andover, Mass). Eighteen swine were anesthetized, and after median sternotomy, the echo probe was applied directly to the surface of the right atrium. To create an atrial septal defect, balloon atrial septostomy and atrial septal defect enlargement were performed. Subsequently, 3 different techniques of atrial septal defect closure were attempted: group I, direct suture closure; group II, closure of the atrial septal defect using the Amplatzer device (AGA Medical Corp, Golden Valley, Minn); and group III, patch closure of the atrial septal defect (n = 6 each). RESULTS: Real-time 3-dimensional echocardiography guidance provided sufficient spatial resolution and a satisfactory frame rate to provide a "virtual surgeon's view" of the relevant anatomy during the entire procedure. All atrial septal defects were enlarged, and the mean final size was 8.5 +/- 1.8 mm. Atrial septal defect closure was successfully accomplished with all the 3 surgical techniques examined. In groups I and III, the needles (1-3 sutures) and staples (6-12 staples) penetrated the tissue and patch material consistently, whereas in group III, the Amplatzer atrial septal defect device was easily deployed. There was no incident device/staple embolization or air introduction. Neither intraoperative 2-dimensional color Doppler echocardiography nor postmortem macro-evaluation revealed any residual shunts. CONCLUSIONS: Beating heart atrial septal defect closure under real-time 3-dimensional echocardiographic guidance is feasible and, unlike catheter-based devices, applicable for any type of secundum atrial septal defect.

Animals↗
PubMed2005

Aortic valvuloplasty in the fetus: technical characteristics of successful balloon dilation.

OBJECTIVES: To describe technical aspects of successful fetal aortic valvuloplasty, with particular attention to balloon size. STUDY DESIGN: We retrospectively reviewed all procedural records and echocardiograms pertaining to 26 attempts at fetal aortic valve dilation performed at a single center over a period of 4 years. We assessed the effect of valvuloplasty as determined by echocardiographic appearance at the time of intervention and in follow-up. RESULTS: In 20 of 26 fetuses who had technically successful aortic valve dilation (median balloon:annulus ratio=1.1), all had improved antegrade flow and 12 had at least mild regurgitation after dilation. Use of an oversized balloon was associated with the onset of moderate or severe aortic regurgitation, seen in 5 fetuses. This aortic regurgitation was well tolerated and improved through the remainder of gestation. CONCLUSIONS: These data imply that fetal aortic valves can be dilated safely with larger balloons than are commonly used for postnatal dilation. The observation of spontaneous improvement in postdilation aortic regurgitation further suggests that fetal valve tissue behaves uniquely.

Aortic Valve Insufficiency↗
PubMed2004

Balloon dilation of severe aortic stenosis in the fetus: potential for prevention of hypoplastic left heart syndrome: candidate selection, technique, and results of successful intervention.

BACKGROUND: Preventing the progression of fetal aortic stenosis (AS) to hypoplastic left heart syndrome (HLHS) requires identification of fetuses with salvageable left hearts who would progress to HLHS if left untreated, a successful in utero valvotomy, and demonstration that a successful valvotomy promotes left heart growth in utero. Fetuses meeting the first criterion are undefined, and previous reports of fetal AS dilation have not evaluated the impact of intervention on in utero growth of left heart structures. METHODS AND RESULTS: We offered fetal AS dilation to 24 mothers whose fetuses had AS. At least 3 echocardiographers assigned a high probability that all 24 fetuses would progress to HLHS if left untreated. Twenty (21 to 29 weeks' gestation) underwent attempted AS dilation, with technical success in 14. Ideal fetal positioning for cannula puncture site and course of the needle (with or without laparotomy) proved to be necessary for procedural success. Serial fetal echocardiograms after intervention demonstrated growth arrest of the left heart structures in unsuccessful cases and in those who declined the procedure, while ongoing left heart growth was seen in successful cases. Resumed left heart growth led to a 2-ventricle circulation at birth in 3 babies. CONCLUSIONS: Fetal echocardiography can identify midgestation fetuses with AS who are at high risk for developing HLHS. Timely and successful aortic valve dilation requires ideal fetal and cannula positioning, prevents left heart growth arrest, and may result in normal ventricular anatomy and function at birth.

Aortic Valve Stenosis↗
PubMed2004

Respiratory symptoms secondary to aortopulmonary collateral vessels in tetralogy of Fallot absent pulmonary valve syndrome.

Hemodynamically significant systemic-to-pulmonary artery collaterals may represent an underappreciated cause of cardiorespiratory compromise in tetralogy of Fallot with absent pulmonary valve (TOF/APV). We retrospectively reviewed the angiographic, magnetic resonance imaging, operative, and autopsy reports of the 50 patients with TOF/APV managed at our institution in the past 10 years and demonstrated that at least 7 of 50 patients (14%) had significant aortopulmonary collaterals.

Aorta, Thoracic↗
PubMed2004

Three-dimensional echocardiography-guided atrial septectomy: an experimental study.

OBJECTIVES: The surgical feasibility of beating-heart atrial septectomy under the guidance of two different types of real-time 3-dimensional echocardiography systems was examined. METHODS: A modified real-time 3-dimensional echocardiography system with a x4 matrix transducer (Sonos 7500; Philips Medical Systems, Andover, Mass) or a mechanical 1-dimensional array transducer (SSD-5500; Aloka Co, Ltd, Tokyo, Japan) was used. Small porcine atrial septal defects (n = 8) were enlarged with a Kerrison bone punch in the tank model. In the animal studies, small atrial septal defects (n = 8) were enlarged with the same device through a transatrial port. In both experiments, the area of the atrial septal defect measured by real-time 3-dimensional echocardiography was compared with the area measured directly. RESULTS: Real-time 3-dimensional echocardiography provided satisfactory images and sufficient anatomic detail for the atrial septectomy in both experimental settings. All the atrial septal defects were successfully enlarged; an increase of as much as 293% of the preoperative atrial septal defect area was achieved in the tank experiment, and an increase of as great as 449% of the preoperative area was achieved in the animal experiment. The size of the atrial shunt was increased significantly after the atrial septectomy relative to that before the surgery (P <.0001). The percentage enlargement of the atrial septal defect measured by real-time 3-dimensional echocardiography was strongly correlated with that measured directly (both r(2) = 0.997, P <.0001) Bland-Altman analysis showed close agreement between the results obtained by the two measurement methods in both models. CONCLUSIONS: Real-time 3-dimensional echocardiography provides satisfactory images and sufficient anatomic detail for atrial septectomy. This experiment demonstrates the surgical feasibility of a beating-heart intracardiac procedure such as atrial septectomy under real-time 3-dimensional echocardiographic guidance.

Animals↗
PubMed2004

Three-dimensional echocardiography-guided beating-heart surgery without cardiopulmonary bypass: a feasibility study.

BACKGROUND: There is no current acceptable approach for intracardiac beating-heart interventions. We have adapted real-time 3-dimensional echocardiography with specialized instrumentation to facilitate beating-heart repair of atrial septal defects and mitral valve plasty to investigate the feasibility of real-time 3-dimensional echocardiography-guided cardiac surgery. METHODS: In experiment I a modified real-time 3-dimensional echocardiography system with x4 matrix transducer was compared with 2-dimensional echocardiography in the performance of common surgical tasks. Completion times, deviation from an ideal trajectory, and an echogenic target were measured. In experiment II porcine atrial septal defects were closed with an original semiautomatic suturing device (n = 4) and with a 5-mm endoscopic stapler and a pericardial or polytetrafluoroethylene patch (n = 4). In experiment III a pulsatile porcine mitral valve model was developed, and suture placement through the anterior and posterior mitral leaflets was performed (n = 8). During all experiments, the operator was blinded to the target and operated on only with ultrasonic guidance. RESULTS: In experiment I, compared with 2-dimensional echocardiographic guidance, completion times improved by 21% ( P <.01) with high-trajectory accuracy, and suture deviation was significantly smaller (2-dimensional echocardiography, 5.4 +/- 2.7 mm; 3-dimensional echocardiography, 1.7 +/- 0.7 mm; P <.05) in real-time 3-dimensional echocardiography-guided tasks. In experiments II and III in both atrial septal defect closure and mitral valve plasty, real-time 3-dimensional echocardiography provided satisfactory images and sufficient anatomic detail for suturing and patch deployment. All surgical tasks were successfully performed with accuracy. CONCLUSIONS: Real-time 3-dimensional echocardiography provides adequate imaging and anatomic detail to act as a sole guide for surgical task performance. These initial experiments demonstrate the feasibility of beating-heart direct or patch closure of atrial septal defects and mitral valve plasty without cardiopulmonary bypass.

Animals↗
PubMed2003

Application of robotics in congenital cardiac surgery.

Over the past 5 years, robotic systems that combine advanced endoscopic imaging with computer-enhanced instrument control have been used for both coronary revascularization and intracardiac procedures in adults. In addition, endoscope positioning systems and articulated instruments with a robotic wrist mechanism have further expanded the potential applications for robotics in cardiac surgery. In pediatric cardiac surgery, potential applications can be divided into simple scope manipulation versus the use of 3-dimensional imaging and a robotic wrist for dissection and reconstruction. A voice-controlled robotic arm for scope manipulation can facilitate current pediatric thoracoscopic procedures such as ligation of patent ductus arteriosus and division of vascular rings. By using an advanced imaging system along with a robotic wrist, more complex extracardiac and even intracardiac procedures can be performed in children. Examples include coarctation repair, septal defect repair, and mitral or tricuspid valvuloplasty. Furthermore, with adequate intracardiac imaging, a robot-assisted off-pump approach to intracardiac pathology is conceivable. New real-time 3-dimensional echocardiography now offers sufficient resolution to enable such procedures, while the addition of instrument tracking, haptic feedback, and novel tissue fixation devices can facilitate safe and reliable intracardiac repair without extracorporeal circulation.

Cardiac Surgical Procedures↗
PubMed2003

Real-time three-dimensional ultrasound for guiding surgical tasks.

OBJECTIVE: As a stand-alone imaging modality, two-dimensional (2D) ultrasound (US) can only guide basic interventional tasks due to the limited spatial orientation information contained in these images. High-resolution real-time three-dimensional (3D) US can potentially overcome this limitation, thereby expanding the applications for US-guided procedures to include intracardiac surgery and fetal surgery, while potentially improving results of solid organ interventions such as image-guided breast, liver or prostate procedures. The following study examines the benefits of real-time 3D US for performing both basic and complex image-guided surgical tasks. MATERIALS AND METHODS: Seven surgical trainees performed three tasks in an acoustic testing tank simulating an image-guided surgical environment using 2D US, biplanar 2D US, and 3D US for guidance. Surgeon-controlled US imaging was also tested. The evaluation tasks were (1) bead-in-hole navigation; (2) bead-to-bead navigation; and (3) clip fixation. Performance measures included completion time, tool tip trajectory, and error rates, with endoscope-guided performance serving as a gold-standard reference measure for each subject. RESULTS: Compared to 2D US guidance, completion times decreased significantly with 3D US for both bead-in-hole navigation (50%, p = 0.046) and bead-to-bead navigation (77%, p = 0.009). Furthermore, tool-tip tracking for bead-to-bead navigation demonstrated improved navigational accuracy using 3D US versus 2D US (46%, p = 0.040). Biplanar 2D imaging and surgeon-controlled 2D US did not significantly improve performance as compared to conventional 2D US. In real-time 3D mode, surgeon-controlled imaging and changes in 3D image presentation made by adjusting the perspective of the 3D image did not diminish performance. For clip fixation, completion times proved excessive with 2D US guidance (> 240 s). However, with real-time 3D US imaging, completion times and error rates were comparable to endoscope-guided performance. CONCLUSIONS: Real-time 3D US can guide basic surgical tasks more efficiently and accurately than 2D US imaging. Real-time 3D US can also guide more complex surgical tasks which may prove useful for procedures where optical imaging is suboptimal, as in fetal surgery or intracardiac interventions.

Humans↗