Biomedical subjects

J W Mathewson

Publications and source records attributed to J W Mathewson.

At least 19 recordsLinked to original sources

PubMed2000

Pediatric digital echocardiography: a study of the analog-to-digital transition.

Limited information is available that describes the practical conversion of a pediatric echocardiography laboratory from videotape to a primarily digital format. To help pediatric echocardiographers begin to make the analog-to-digital transition, we report our pediatric digital acquisition protocol and the acquisition and storage parameters of 1000 unselected, consecutive digitally acquired studies of pediatric patients with known or suspected congenital or acquired heart disease. With the use of our acquisition protocol, a complete normal study requires 46 moving clips and 12 still-frame images. Five hundred consecutive patient studies acquired with "high" JPEG (Joint Photographers Experts Group) compression (group 1) were compared with the next 500 examinations acquired using "medium" JPEG compression (group 2) for number of moving clips, still images, and megabytes of storage space. No intergroup difference was found in the number of moving clips or still images. When JPEG compression was decreased from high to medium, the average clip storage requirement per patient increased, and the number of patients stored per 230-MB magneto optical disk decreased significantly. Non-ECG-triggered timed single-plane clips and still images required significantly more storage space than ECG-triggered single-beat clips and still images. The frequency of multiplane sweeps was.03% and was independent of diagnosis. With the use of high JPEG compression, the digital storage cost per patient was $1.90, which was 6.0 times greater than that for simultaneously recorded 120-minute VHS videotape. Many features of the digital paradigm, including decreased MOD storage space, enhanced serial study comparisons, random image access, and improved image quality, mitigate this cost differential.

Analog-Digital Conversion↗

PubMed1999

Automatic control design for a dynamic knee-brace system.

A self-contained electronically controlled dynamic knee-brace system (DKBS) has been designed and tested which allows knee flexion during swing phase, but restricts flexion during the stance phase of gait. Cardiovascular energy measurements indicate that DKBS use allowed a more energy efficient gait.

Adult↗

PubMed1997

Filmless multimedia display following cardiac catheterization.

In traditional cardiac catheterization laboratories, anatomic images are acquired onto 35-mm cine film and presented in series with related information days, weeks, or months later to an audience of decision-makers. These data are projected onto a convenient light-colored wall or silver screen, while echocardiograms and electrophysiologic data are displayed using small single-user computer monitors. This presentation format is not ideal, because full audience participation is not fostered, image quality may be degraded, and small computer screens can be adequataly visualized only by those individuals immediately in front of them. Modern video multimedia systems now make an ideal data presentation format practical, in which all types of media including digitally acquired angiograms can be displayed in parallel with full annotation, using large diagonal multisync color monitors. This communication discusses how to design a multimedia conference center in which remotely acquired filmless digital images can be displayed and processed together with all other pertinent cardiac multimedia to a large audience.

Cardiac Catheterization↗

PubMed1995

Percutaneous use of stents to correct pulmonary artery stenosis in young children after cavopulmonary anastomosis.

Pulmonary artery distortion is a risk factor among candidates for the Fontan procedure. In 57 patients evaluated by catheterization after successful cavopulmonary anastomosis, 8 had proximal left pulmonary artery (LPA) stenosis, either discrete (4 patients) or long segment (4 patients). Median age was 27 months (range 19 to 60 months). Median weight was 11.4 kg (range 9.1 to 20.0). Mean diameter at LPA stenosis was 4.4 +/- 0.4. Proximal right pulmonary artery mean diameter was 10.4 +/- 1.0 mm. After angiographic and hemodynamic assessment, short 11F sheaths were placed in the right internal jugular (6 patients) or subclavian veins (2 patients). Pulmonary artery angioplasty and stent placement were performed. LPA stenoses were enlarged using 10 Palmaz stents dilated to 10 mm (7 patients) or to 12 mm (3 patients). Poststent angiograms showed that narrowest LPA dimensions were significantly enlarged to 9.9 mm +/- 1.0 mm, p < 001). There were no complications. Follow-up studies (catheterizations in 4 patients, echocardiograms in 8 patients) were performed 4 to 9 months after stent implantation. No restenosis was observed. Five patients had completion of their Fontan procedures; three patients are pending Fontan completion. This study demonstrates the efficacy and safety of the percutaneous use of Palmaz stents to correct pulmonary artery stenosis in young children after cavopulmonary anastomosis.

Child, Preschool↗

PubMed1994

Percutaneous closure of the small patent ductus arteriosus using occluding spring coils.

OBJECTIVES: This report summarizes our experience with the use of occluding spring coils to close the small patent ductus arteriosus. BACKGROUND: Several patent ductus arteriosus occluders (most notably the Rashkind device) have been developed and studied. Occluding spring coils have been used to close abnormal vessels and vascular connections. We previously reported the use of occluding spring coils to close the small patent ductus arteriosus in a small group of patients. This report describes our series of patients having patent ductus arteriosus closure with occluding spring coils. METHODS: Between June 1990 and June 1993, 30 patients underwent cardiac catheterization to have patent ductus arteriosus closure by occluding spring coils. Selection criteria were age > 6 months and narrowest patent ductus arteriosus internal dimension < or = 3.0 mm by color flow imaging. Definitive selection was based on review of aortograms performed at catheterization. A 5.2F coronary catheter was used to deliver one or two standard occluding spring coils. A loop was delivered in the main pulmonary artery, and the remainder of the coil was delivered across the patent ductus arteriosus and into the aortic diverticulum. Patent ductus arteriosus closure was confirmed by aortography or color flow imaging, or both. Follow-up after coil placement occurred at 6 weeks and 6 months and included two-view chest radiography, echocardiography and color flow imaging. RESULTS: Of the 30 patients, 29 had successful implantation by one (27 patients) or two (2 patients) occluding spring coils. Of these 29 patients, 19 had a clinically apparent and 10 had a silent patent ductus arteriosus. Average ductus minimal internal dimension was 1.7 mm (range 1.0 to 3.0). Complete closure of the ductus was confirmed in 27 patients by aortography or color flow imaging or both (in 24 within 4 h, in 2 after 6 weeks and in 1 after 6 months). Six weeks after implantation, two patients had a tiny residual patent ductus arteriosus noted on color flow imaging. One patient did not have successful implantation. This patient had a 3.2-mm ductus, and two coils migrated to the distal left pulmonary artery and could not be retrieved. There were no deaths or any significant complications noted during early or late follow-up in these patients. CONCLUSIONS: Occluding spring coils may have additional application in closing the small patent ductus arteriosus.

Aortography↗

PubMed1993

Energy cost of ambulation with different methods of foot and ankle immobilization.

In order to measure the energy cost of immobilization of the foot and ankle during ambulation, 14 healthy male volunteers exercised while wearing various immobilization devices. Oxygen consumption, oxygen cost, cardiac output, minute ventilation, heart rate, stroke volume, stride length, and stride frequency were determined at a steady state of exercise as the subjects walked on a treadmill at 80 m/min (equivalent to the comfortable walking speed of approximately 3 mi/h). Each subject was tested with three different types of immobilization devices: a short leg walking cast, a prefabricated lower leg orthosis, and a rigid-soled surgical shoe. The results were compared with those for the same men ambulating without an immobilization device. Ambulation with the short leg walking cast and the prefabricated lower leg orthosis required significantly more energy in comparison with control values (all p values < 0.006) in terms of oxygen cost, cardiac index, oxygen consumption, and minute ventilation. However, when the rigid-soled surgical shoe was worn, energy consumption as measured by all parameters was not significantly increased compared with control values. Comparison of the findings for the short leg walking cast and the prefabricated lower leg orthosis showed no significant differences in any parameter of energy consumption. Stride length, however, was significantly shorter in the short leg walking cast compared with all immobilizers tested.

Adult↗

PubMed1993

High-risk angioplasty. Coarctation of the aorta after Norwood Stage 1.

This report describes 2 patients with hypoplastic left heart syndrome who developed severe coarctations of the aorta after Norwood Stage I procedures and subsequently survived recurrent ventricular fibrillation during successful percutaneous angioplasty. Although ventricular fibrillation has not been associated with hypoplastic left heart syndrome, postoperative Norwood Stage I, or angioplasty of isolated coarctations of the aorta, we believe that the complex physiology of our patients created conditions that precipitated ventricular tachycardia and ventricular fibrillation. We strongly recommend that follow-up of infants with hypoplastic left heart syndrome after Norwood Stage I operations be meticulous; that even mild coarctation be treated aggressively, to avoid progression to high-risk situations; and that interventionalists be prepared to manage malignant ventricular dysrhythmias whenever postoperative Norwood Stage I patients undergo percutaneous angioplasty for coarctation of the aorta.

Angioplasty, Balloon↗

PubMed1991

The Damus-Fontan procedure.

The Damus-Kaye-Stansel operation is a useful technique for the treatment of complex cyanotic congenital heart disease when there is obstruction between the systemic ventricle and the aorta. Modifications of the technique include transection of the aorta and the pulmonary artery, anastomosis of the contiguous aortic and pulmonary walls, and connection of the distal aorta to the perimeter of the new bivalved proximal great artery. In addition, the bidirectional cavopulmonary shunt technique can be used with or without the Fontan procedure. Six patients underwent a Damus-Fontan operation, and all survived. Two patients underwent the Damus-cavopulmonary shunt (hemi-Fontan) procedure, and 1 survived. The postoperative status of the 7 survivors is good to excellent. Follow-up ranges from 2 months to 7 1/2 years.

Anastomosis, Surgical↗

PubMed1991

The cryopreserved homograft valve in the pulmonary position: mid-term results and technical considerations.

Since September 1985, 60 cryopreserved homograft valves (12 aortic and 48 pulmonary) have been implanted in the pulmonary position in 56 patients. There were 34 primary operations and 26 reoperations. The ages ranged from 15 days to 22 years; the follow-up ranged from 1 month to 5 1/2 years. The operative mortality was 3.3% (2/56). There were two late deaths (not valve related). Five patients underwent replacement of the homograft; in one patient the homograft was replaced with a heterograft valve. Pathological analysis of the explanted homografts revealed calcification of the wall with satisfactory leaflet function. The leaflets were relatively acellular. No evidence of inflammation or rejection was detected. Four explants were performed for nonvalve-related indications. There are 51 long-term survivors with a homograft in place. Forty-eight are in excellent condition; three are mildly symptomatic (not valve related). Benign pulmonary insufficiency murmurs are present in 29 patients. The presence of trivial or mild insufficiency was independent of the technique of implantation. In general, cryopreserved homograft valves function well in the right ventricular outflow tract. Longer term follow-up is necessary to confirm the superiority of the cryopreserved homograft when compared to the porcine heterograft in the right ventricular outflow tract.

Adolescent↗

PubMed1990

The bidirectional cavopulmonary shunt.

The bidirectional cavopulmonary shunt improves systemic arterial oxygen saturation without increasing ventricular work or pulmonary vascular resistance. Since 1983, 17 patients have undergone a cavopulmonary shunt procedure (five primary operations, 12 secondary operations). Diagnoses were single ventricle complex (n = 4), hypoplastic right heart syndrome (n = 10), and hypoplastic left ventricle (n = 3). Age at primary operation ranged from 3 1/2 to 30 months (median 6 months). Weight ranged from 3.5 to 9.7 kg. Age at secondary operation ranged from 10 months to 14 years (median 15 months). Seven cavopulmonary shunt operations were performed without cardiopulmonary bypass (six via thoracotomy and one via sternotomy) and 10, with cardiopulmonary bypass. All patients in the bypass group had additional procedures: takedown of modified Blalock-Taussig shunt, seven patients; revision of right ventricular outflow tract, four patients; reconstruction of pulmonary arteries, four patients; tricuspid valvuloplasty, one patient; and Damus procedure, one patient. There was one (1/17) operative death (Damus procedure). One patient required early revision. Follow-up ranges from 1 to 53 months (median 23 months). Twelve of 16 had a good to excellent late result, with a rise in mean arterial oxygen saturation from 69% to 83%. Three patients died late (4 to 53 months) (pulmonary vascular disease, pulmonary arteriovenous malformations, and pneumonia, one patient each). There was one late failure (converted to Glenn shunt). The cavopulmonary shunt is an excellent palliative procedure when right atrium-pulmonary artery connection (modified Fontan) must be deferred because of age, weight, or anatomic considerations. Five patients have undergone right atrium-pulmonary artery connection later. In addition, at the time of the modified Fontan operation, the cavopulmonary shunt approach may optimize the anatomic connection (eight additional patients).

Adolescent↗

PubMed1989

Late reoperation for systemic atrioventricular valve regurgitation after repair of congenital heart defects.

Since 1979, 17 infants and children have undergone reoperation for systemic atrioventricular (AV) valve regurgitation 6 weeks to 7 years after repair of congenital heart defects. Prior operations were repair of incomplete or complete AV canal (14 patients), Mustard repair of complex transposition of the great arteries including ventricular septal defect closure (2 patients), or first-stage operation for hypoplastic left heart (1 patient). Age ranged from 6 months to 11 years. In 12 of the 17 patients (10, AV canal; 1, transposition; 1, hypoplastic left heart), valve reconstruction was possible. Operative techniques included a combination of septal cleft approximation, leaflet resection, commissural annuloplasty, or ring annuloplasty. There were no operative deaths, and there were no reoperations in the repair group. The condition of these patients has improved. Follow-up ranges from 1 month to 9 years (mean follow-up, 4.1 years). Five of the 17 patients (4, AV canal; 1, transposition) underwent valve replacement. There were no operative deaths. Follow-up ranges from 3 to 8 years. Three patients later underwent re-replacement of the prosthetic valve; there was 1 late death. The condition of all 4 survivors is improved. Substantial AV valve regurgitation can occur months or years after repair of congenital heart defects. A combination of reconstructive techniques may be useful in preserving native valve function and avoiding systemic AV valve replacement.

Child↗

PubMed1988

The cryopreserved homograft valve in the pulmonary position: early results and technical considerations.

Since September, 1985, 20 patients have undergone implantation of a homograft valve in the pulmonary position (16 pulmonary, 4 aortic). There were 11 primary operations and 9 reoperations. In 7 of 11 primary operations the homograft valve was utilized as a composite conduit with a short Dacron extension. In four of five reoperations for a failed porcine valved conduit, a composite homograft conduit was used. Four patients underwent implantation of a free homograft in a previously repaired right ventricular outflow tract (RVOT). Age ranged from 15 days to 22 years. There was one operative death (5%), a seven-week-old infant with truncus arteriosus. Long-term follow-up ranges from 1 to 30 months. Clinical performance has been satisfactory in 18 of 19 patients. One patient undergoing free implantation of a pulmonary valve in the RVOT required replacement at 18 months with a porcine valve. In this patient, pulmonary insufficiency was caused by distortion of the annulus secondary to dilatation and pulmonary hypertension. Nine of 18 survivors do not require medication. Eleven of 18 have trivial to mild pulmonary insufficiency murmurs without symptomatology. The homograft valve is extremely useful in reconstruction of the right heart, however, early insufficiency murmurs have been noted. Distortion of the valve annulus may contribute to the early onset of a benign insufficiency murmur. Residual distal obstruction or pulmonary hypertension may be a contraindication to the use of a free homograft in the orthotopic position.

Adolescent↗

PubMed1988

Balloon dilatation of stenotic right ventricle-to-pulmonary artery conduits.

In seven children with obstructed right ventricle-to-pulmonary artery conduits, balloon dilatation (BD) was performed 10-58 months after insertion of the conduit. Average valve gradient was reduced from 69 to 32 mmHg. Obstruction at the conduit-branch pulmonary artery connection became apparent after dilatation of the valve; these distal stenoses also were dilated. It is concluded that the useful lifetime of a right ventricle (RV) to pulmonary artery (PA) conduit may be extended by BD of an obstructed biological valve and/or BD of a stenotic conduit-pulmonary artery anastomosis.

California↗

PubMed1988

Experience with Damus procedure.

Sixteen patients with complex cyanotic congenital heart disease underwent an operation involving the use of the aorta and the main pulmonary artery as the egress for systemic arterial blood flow (the Damus-Kaye-Stansell operation, modified as discussed). The indication for this approach was either preoperative aortic outlet obstruction or likelihood that the repair would produce such obstruction. A modification of the original technique is introduced that involves transection of both great arteries, anastomosis of the contiguous aortic and pulmonic walls, and connection of the distal aorta to the perimeter of the new (bivalved) great artery. Eleven of the 16 patients survived operation: six of six who underwent a concurrent Fontan operation, four of six who underwent a concurrent right-ventricle-to-pulmonary-artery-conduit procedure, and one of four who underwent a concurrent systemic-pulmonary shunt procedure. Postoperative status in the 11 survivors is good: one patient has a gradient from the left ventricle to the aorta, 10 of 11 have little or no aortic regurgitation, and the remaining patients have a normal physiological status. We conclude that the Damus procedure is a useful addition to the surgical armamentarium for treatment of certain types of cyanotic congenital heart disease.

Angiography↗

PubMed1987

Balloon dilatation of porcine bioprosthetic valves in the pulmonary position.

Balloon dilatation (BD) of bioprosthetic valves was investigated in vivo and in vitro. Four children with stenotic bioprosthetic porcine valves in the pulmonary position underwent BD of the valve 10 to 24 months after its insertion. Average valve gradient was reduced from 47.5 to 27 mm Hg. Obstruction at the conduit-branch pulmonary artery connection became apparent after dilatation of the valve. These distal stenoses were also dilated. BD technique was tested in vitro with the use of nonstenotic valves in fresh conduits. No damage to the valve or to the conduit was found when oversized balloons were used in a standard fashion or intentionally inflated until rupture. It is concluded that conduit replacement may be deferred by balloon dilatation of obstructed biological valves and/or a stenotic conduit-pulmonary artery anastomosis.

Angioplasty, Balloon↗

PubMed1984

Shared coronary arteries and coronary venous drainage in thoracopagus twins.

A pair of type B thoracopagus twins with complex cyanotic heart disease had shared coronary arteries and coronary venous drainage. Surgical separation was not attempted and the twins died at 10.5 months of age. Antemortem angiography demonstrated that Twin A's right coronary artery supplied Twin B's diaphragmatic and anterior ventricular myocardial free wall. A midline communication existed between each twin's right atrium at a common coronary sinus. The crossing coronary artery coursed alongside this connection and was visualized echocardiographically. At postmortem examination, the great cardiac vein of Twin A drained into the orifice of the common coronary sinus on Twin B's side of the midline. In five of six previously reported cases, the children died at attempted separation shortly after ligation of the interatrial communication. This may have been because of occlusion of a coronary artery or acute obstruction of a coronary vein. Consideration of separation of type B thoracopagus twins requires anatomic delineation of the coronary arteries and veins.

Arteries↗

PubMed1984

Systemic-pulmonary shunts in infants and children. Early and late results.

From September, 1978, to January, 1983, 44 cyanotic infants and children underwent a systemic-pulmonary artery shunt for the treatment of reduced pulmonary blood flow. Age ranged from 18 hours to 4 years (mean age = 0.49 years). Weight ranged from 1.7 kg to 13.2 kg (mean weight = 4.9 kg). There were 12 classic Blalock-Taussig shunts, five central polytetrafluoroethylene shunts, six interposition modified Blalock-Taussig shunts, and 21 Great Ormond Street type of modified Blalock-Taussig shunts. No direct aorta-pulmonary artery anastomoses were performed. There was one postoperative death (1/44 = 2.3%) in a 1,700 gm neonate born with pulmonary atresia and intact ventricular septum (shunt patent). Four shunts required early revision: one thrombosed central shunt, a kinked patent interposition Blalock-Taussig shunt, a small but patent Blalock-Taussig shunt, and one excessive Great Ormond Street type of Blalock-Taussig shunt. Two late deaths were probably shunt-related: one Blalock-Taussig and one central. All four types of shunts provided good palliation, but the Great Ormond Street type of Blalock-Taussig shunt is our preferred shunt because of (1) low operative risk, (2) predictable patency (100% in our series), (3) lack of distortion of pulmonary arterial anatomy, and (4) technical ease of insertion as well as takedown.

Birth Weight↗

PubMed1984

Containing costs in the treatment of congenital heart disease.

In the Congenital Heart Program at San Diego Children's Hospital, alterations in medical practice have reduced costs without impairing quality or access. Pediatric cardiac catheterization was done in 483 consecutive elective patients without overnight hospital stay. Hospital readmission was required in one patient for psoas tendinitis. Avoiding overnight hospital stay minimized attendant risks of hospital care, lessened psychosocial trauma and reduced the average hospital bill by $493 (29%). Hospital stay was also reduced for elective surgical correction of congenital heart disease on a case-by-case basis. Review of 151 consecutive cases (1978 through 1982) showed a decrease in both preoperative days in hospital and postoperative days in an intensive care unit. The duration of the postoperative stay was shortened from 6.8 days in 1978-1979 to 4.4 days in 1982 (P <.05). No increase in morbidity and no mortality resulted from the shortened perioperative hospital stay. Financial savings from this process averaged $991 per procedure.Diagnostic tests were reassessed and many precatheterization laboratory tests were eliminated. Without change in new patients seen or surgical volume, the use of cardiac catheterization decreased from 241 procedures in 1981 to 161 in 1982 and the number of operations without catheterization increased (11 to 22, 1981 to 1982). No increase in surgical morbidity or mortality was found comparing those diagnosed only by echocardiography with those who had preoperative cardiac catheterization. The decrease of 80 catheterizations in one year resulted in a savings of $188,800.True cost containment (reducing cost without reducing quality) can be accomplished in congenital heart programs. Similar cost containments in other disciplines may also be achieved.

California↗