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Biomedical subjects

J E Lock

Publications and source records attributed to J E Lock.

At least 109 records · Page 6Linked to original sources
PubMed1989

Balloon dilation of postoperative right ventricular outflow obstructions.

Balloon dilation was attempted in 16 patients, aged 5 months to 19.5 years, with right ventricular outflow obstruction after repair of congenital heart defects. Stenosis of a valved conduit between the pulmonary ventricle and pulmonary artery was present in nine patients with a mean transvalvular peak systolic ejection gradient of 61.6 +/- 21.0 mm Hg and a mean right ventricle to aorta pressure ratio of 0.9 +/- 0.2. Supravalvular pulmonary stenosis was present in seven patients; in five, stenosis was at the anastomotic site after the arterial switch operation with a mean peak systolic ejection gradient of 72.2 +/- 10.6 mm Hg and mean right ventricle to aorta pressure ratio of 0.93 +/- 0.05. The other two patients had stenosis at a previous pulmonary artery band site with a peak systolic ejection gradient of 60 and 65 mm Hg and right ventricle to aorta pressure ratio of 0.75 and 0.72, respectively. Balloon dilation was successful in three of nine patients with a valved conduit; two of them had additional successful balloon dilation of the right pulmonary artery. In five of the nine patients (including one with successful dilation) the conduit was replaced 5.7 +/- 4.5 months after balloon dilation. Balloon dilation was successful in only one of the five patients with supravalvular pulmonary stenosis after the arterial switch operation and partially successful in the two patients with supravalvular pulmonary stenosis at a previous band site. The success rate of balloon dilation of postoperative right ventricular outflow obstruction is much lower than that for other right heart obstructions.

Bioprosthesis↗
PubMed1989

Coil embolization to occlude aortopulmonary collateral vessels and shunts in patients with congenital heart disease.

Gianturco coils were used to embolize 77 vessels in 54 patients: 58 aortopulmonary collateral vessels, 14 Blalock-Taussig shunts, 3 arteries involved in pulmonary sequestrations and 2 venae cavae. Embolization resulted in total occlusion in 53 (69%), subtotal occlusion in 19 (25%) and partial occlusion in 3 (1 intentional). Two embolizations failed to reduce flow. Thus, 72 (95%) of 76 embolizations in which complete occlusion was the intended result resulted in total or subtotal occlusion. Analysis of the results demonstrates that completely occluded collateral vessels were longer and had a smaller diameter than did incompletely occluded vessels. Complications included six cases of inadvertent embolization to the pulmonary arteries (n = 5) or the aorta (n = 1); three were retrieved and three were left without symptoms. In addition, there was a case of severe hemolysis after intentional partial occlusion of a Blalock-Taussig shunt. The results demonstrate that coil embolization can be an effective procedure for managing a wide variety of aorto-pulmonary collateral vessels and shunts in children with congenital heart disease.

Adolescent↗
PubMed1989

Transcatheter closure of atrial septal defects. Experimental studies.

Recent experience with the spring-loaded patent ductus arteriosus (PDA) occluder has demonstrated several advantages of this device in the closure of intracardiac defects compared with previously described techniques. Pathologic and animal model studies were performed to identify which atrial septal defects (ASDs) might be suitable for device closure and to test a new septal closure double umbrella. Fifty specimens from the Cardiac Registry with unrepaired ASD secunda (2 degrees) were analyzed. Mean ASD size was 8 x 10 mm (range, 3 x 4 to 30 x 30 mm); 80% (n = 40) of ASDs were judged closable with the new device. ASD closure was attempted in four lambs with the Rashkind (hooked single umbrella) ASD occluder. One of four umbrellas was correctly positioned; no ASDs were closed. A new double-hinged ("clamshell") umbrella device was designed: eight ASD closures were attempted with this device (defects ranged from 8 to 20 mm in diameter). Six of eight umbrellas were correctly positioned; four of four animals observed more than 1 day appeared to have complete closure on postmortem examination with endothelialization of the device. We conclude that 1) most ASD 2 degrees are far enough from vital structures to permit closure, 2) initial placement of hooked umbrellas is often incorrect and cannot be altered, 3) clamshell double umbrellas were successfully placed in six of eight attempts, and 4) endothelialization of closed ASDs appears complete within weeks of implantation. These preliminary studies appear promising and support testing the clamshell ASD device in clinical trials.

Animals↗
PubMed1989

Neonatal critical valvar aortic stenosis. A comparison of surgical and balloon dilation therapy.

Balloon aortic valvotomy (BAV) is an alternative to surgical valvotomy in infants and children. We compared BAV in 16 consecutive neonates (1985-1988) to surgical valvotomy in a prior group of 16 consecutive neonates (1978-1984). Both groups were comparable in terms of age, weight, hemodynamic data, left ventricular size, and associated lesions. There were six early and one late deaths after surgery. Five out of six neonates requiring a second operation died. Left ventricular size (measured in 13 neonates) had some influence on survival after surgery: three of three with small or hypoplastic left ventricles and three of 10 with normal-sized left ventricles died. After BAV, there were three early deaths, two patients who underwent stage I palliation of hypoplastic left heart syndrome, and two late deaths. As with surgical valvotomy, left ventricular size seemed to influence survival after BAV: five of six with small or hypoplastic left ventricles died or underwent stage I palliation for hypoplastic left heart syndrome and two of nine with normal-sized left ventricles died. At follow-up (26 +/- 17 months) in six patients in the surgical group, the peak systolic ejection gradient (PSEG) was 52.2 +/- 23 mm Hg and left ventricular end-diastolic pressure (LVEDP) 18.2 +/- 5.2 mm Hg. Aortic regurgitation was mild in five and moderate in the sixth patient. At follow-up (17.6 +/- 7.8 months) in nine patients in the balloon dilation group, the PSEG was 45.6 +/- 11 mm Hg in five patients at catheterization and 43.8 +/- 22.9 mm Hg in four patients by echocardiography-Doppler. Aortic regurgitation was mild in three and absent in the other six patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Aortic Valve↗
PubMed1989

Interventional catheterization of left heart lesions, including aortic and mitral valve stenosis and coarctation of the aorta.

The current status of percutaneous balloon valvotomy for aortic, subaortic, and mitral stenosis and angioplasty of aortic arch obstructions are reviewed. Results from the authors and other laboratories are discussed in relation to technique and other factors such as patient age and underlying pathology. Current indications for these procedures are reviewed.

Adolescent↗
PubMed1989

The neonate with critical congenital heart disease: repair--a surgical challenge.

Primary neonatal repair of congenital heart defects offers a number of potential advantages over a two-stage approach, but the application of this principle has been limited by the perceived increased risk of neonatal repair. However, the patient with palliative CHD continues to suffer from secondary effects on the central nervous system, the pulmonary arteries, the airways, and the heart itself. Because these consequences have been increasingly recognized, we have undertaken primary repair of a variety of defects within the first months of life. From January 1983 through August 1988, 304 neonates with a critical congenital heart defect underwent primary repair with deep hypothermic circulatory arrest or low flow perfusion techniques. The total mortality rate was 11.8%. The largest number of patients had transposition of the great arteries--167 neonates--with a total hospital mortality of 8.9%. Aspects of preoperative evaluation and management, intraoperative care, including anesthesia and cardiopulmonary bypass, and deep hypothermia (with or without circulatory arrests), as well as postoperative management, are discussed. These data suggest that many forms of complex congenital heart defects may be successfully repaired during the neonatal period. Improved methods of preoperative resuscitation and postoperative care have contributed to these results. Follow-up hemodynamic and electrophysiologic studies have confirmed the advantages of early repair. Elective repair of the neonate with a complex congenital heart defect looms as a goal in the not-too-distant future.

Cardiopulmonary Bypass↗
PubMed1988

Gross and histologic anatomy of total anomalous pulmonary venous connections.

Among 49 heart specimens with total anomalous pulmonary venous connection (TAPVC), obstruction to pulmonary venous flow was present in all 13 cases with TAPVC below the diaphragm and in 53% of 36 cases with TAPVC above the diaphragm. Obstruction was produced by extrinsic pressures on the vein, intrinsic narrowing of the vein, or both. The histology of the narrowed veins was extremely variable, ranging from atrophy of the vein wall to hypertrophy of intima, media-adventitia, or both. Balloon dilation of narrowed veins was performed in 3 cases, without clinical or anatomic evidence of success.

Brachiocephalic Veins↗
PubMed1988

Interventional catheterization in pediatric congenital and acquired heart disease.

The present status of catheter-directed therapy in pediatric congenital and acquired heart disease is reviewed. Balloon pulmonary valvotomy, established as the procedure of choice for children and adults with isolated pulmonary stenosis, has now been extended to neonates with critical pulmonary stenosis. Balloon mitral and aortic valvotomy are being performed for congenital and acquired stenoses, although indications and optimal techniques remain to be established. Balloon angioplasty of coarctation effectively relieves obstruction in native and post-operative aortic arch stenoses, but remains controversial due to late aneurysm formation. Balloon angioplasty of branch pulmonary artery hypoplasia and stenosis, despite a relatively low success rate and significant complications, remains the procedure of choice due to lack of better therapeutic options. Transcatheter closure of congenital and acquired vessels and defects is being performed with increasing frequency. Embolization of aortopulmonary collaterals and shunts using Gianturco coils is safe and effective in selected patients. Although Rash-kind umbrellas are most commonly used for closure of a patent ductus arteriosus, their use, especially in closing intracardiac defects, remains investigational.

Angioplasty, Balloon↗
PubMed1988

Are routine preoperative cardiac catheterization and angiography necessary before repair of ostium primum atrial septal defect?

Two-dimensional and Doppler echocardiography were compared with cardiac catheterization and angiography in the preoperative evaluation of ostium primum atrial septal defect. Preoperative echocardiographic examinations as well as operative reports of all patients (33 patients aged 2 months to 23 years at surgery) with ostium primum atrial septal defect or transitional atrioventricular (AV) canal defect having had echocardiography and surgical repair at The Children's Hospital, Boston from July 1983 to January 1986 were retrospectively reviewed. Original cardiac catheterization and angiographic reports also were reviewed. Preoperative echocardiography resulted in no false positive or false negative primary diagnoses when compared with the diagnoses obtained at preoperative angiography or surgery. Doppler assessment of mitral regurgitation correlated well with angiographic (93% agreement) and intraoperative (85% agreement) assessments of mitral regurgitation to within two diagnostic categories on the six level scoring system used. There was reasonably good agreement between the two-dimensional echocardiographic estimate of right ventricular systolic pressure and that measured at catheterization when expressed as percent of the simultaneous left ventricular pressure. Seven of nine ventricular septal defects observed intraoperatively were noted on preoperative echocardiography; five of these defects were detected on preoperative angiography. A variety of other surgically confirmed associated cardiovascular defects were observed by both preoperative techniques. However, echocardiography appeared to be superior to angiography for evaluation of AV valve morphology and papillary muscle architecture. This study implies that in children with typical clinical and two-dimensional echocardiographic and Doppler findings for ostium primum atrial septal defect or transitional AV canal defect, routine preoperative cardiac catheterization and angiography are unnecessary.

Adolescent↗
PubMed1988

Balloon dilation of critical pulmonary stenosis in the first week of life.

Although balloon dilation of valvular pulmonary stenosis is established in infants and children, the techniques for and results of balloon dilation in neonates with critical pulmonary stenosis remain largely unreported. Since January 1, 1985, six successive neonates with critical pulmonary stenosis (aged 1 to 6 days) underwent attempted balloon dilation. Each was cyanotic and three of the six were on prostaglandin E1 therapy and three required tracheal intubation and ventilation. All had suprasystemic right ventricular pressures (mean 122.8 +/- 6.8 mm Hg). After hemodynamic evaluation and right ventricular angiography, the valve was crossed in five patients, and was first dilated with a low profile, 5 or 6 mm diameter, 2 cm long balloon. At least one more balloon was used in each patient, the largest being 95 to 133% of the diameter of the pulmonary valve anulus. The anulus size was 6.8 +/- 1.1 mm and the largest balloon size used was 6 to 10 mm. Right ventricular pressure decreased to nearly systemic level or less in five of five patients (58.8 +/- 6.7 mm Hg). Pressure gradients, measured in four infants, were 7, 12, 16 and 35 mm Hg, respectively, but were unreliable indicators of obstruction because of a patent ductus arteriosus. The five patients were discharged 3 to 8 days after balloon dilation. All are currently symptom free 10.6 +/- 11.7 months later, and all but one are believed clinically to have mild obstruction. Complications included iliac vein occlusion (n = 1) and complete right bundle branch block (n = 1). Although follow-up has been brief, neonates with critical pulmonary stenosis can safely undergo balloon dilation, usually with good short-term results.

Catheterization↗
PubMed1988

Transcatheter closure of a calcified patent ductus arteriosus in an elderly man.

Successful transcatheter closure of a calcified patent ductus arteriosus was performed in a symptomatic 78 year old man. Cardiac catheterization revealed a left to right shunt across the patent ductus arteriosus with a pulmonary to systemic flow ratio of 2.8:1. Calcification of the ductus and severe lung disease increased the risk of surgical patent ductus arteriosus closure. A 17 mm Rashkind double umbrella was positioned in the ductus percutaneously by way of the femoral vein. After closure of the ductus there was marked hemodynamic improvement and the patient was discharged with improved exercise tolerance. Transcatheter closure of patent ductus arteriosus may be a viable option for the elderly patient too sick to withstand cardiovascular surgery.

Aged↗
PubMed1988

Pulmonary and systemic vascular effects of serotonin in conscious newborn lambs.

There is evidence that serotonin (5-hydroxytryptamine) may be released from pulmonary neuroendocrine cells during hypoxia in animals. Because there are few data regarding serotonin's effect on the immature pulmonary circulation, we studied the direct pulmonary (and systemic) vascular effects of this amine in awake lambs. As has been observed in mature animals, we found that serotonin is a powerful pulmonary and systemic vasoconstrictor, with a threshold of 3 micrograms/kg in immature lambs. However, unlike in mature animals, phenoxybenzamine, 2 mg/kg, prevented both the pulmonary (and systemic) vasoconstriction seen with serotonin. Serotonin is a powerful pulmonary vasoconstrictor in immature lambs, which is consistent with the idea that release of serotonin from pulmonary neuroendocrine cells may play a role in the hypoxic pulmonary vasoconstrictor response.

Animals↗
PubMed1988

Late results in patients with tetralogy of Fallot repaired during infancy.

Between 1973 and 1985, 220 infants (age 1 day to 18 months, mean = 7 months) underwent repair of tetralogy of Fallot (TOF) or TOF/pulmonary atresia with 17 early deaths. Follow-up status was ascertained for 184 of 203 survivors (91%) at a postoperative interval of 2 to 185 months (mean = 60 months). Significant residual hemodynamic lesions included ventricular septal defect in three, and right ventricular outflow gradient in excess of 40 mm Hg in 24. Reoperation or interventional catheter procedures were performed in 31 of 184 (17%) patients. All postoperative electrocardiograms were reviewed; only two of 184 patients had ventricular ectopy on any tracing. Holter data from 41 patients revealed one with sinus node dysfunction, 12 with Lown grade 1 ectopy, and one with Lown grade 2 or greater. Conduction defects, evaluated by electrocardiographic and electrophysiologic measurements, were not different from those reported for TOF patients undergoing repair at later ages. No study patient received antiarrhythmic medication, although one required a pacemaker for sinus node dysfunction. There were three late deaths, all unrelated to arrhythmia. TOF repair in infancy appears to be associated with an acceptable hemodynamic outcome, and a low incidence of ventricular ectopy and sudden death at 5 year follow-up.

Arrhythmias, Cardiac↗
PubMed1988

Outpatient closure of the patent ductus arteriosus.

We have modified and applied to selected outpatients the transvenous approach to correction of patent ductus arteriosus (PDA) with the Rashkind PDA Occluder. Modifications included establishing the diagnosis and PDA anatomy before catheterization with echocardiography. The sedation/anesthetic regimen was altered to meet the needs with respect to transcatheter PDA closure rather than diagnostic cardiac catheterization. Anticoagulation was avoided. A strategy for management of pin entrapment in the foam was devised. Residual trans-PDA flow after umbrella placement was temporarily occluded with balloon-tipped catheters. These modifications were used in 23 consecutive patients with uncomplicated PDA. Closure was successful in each child. Nineteen of 23 patients were discharged on the day of the procedure. No serious complications were encountered.

Adolescent↗
PubMed1988

Balloon dilation of congenital aortic valve stenosis. Results and influence of technical and morphological features on outcome.

We evaluated dilation technique (n = 80) and aortic valve morphology by two-dimensional echocardiography (n = 58) in patients with congenital aortic valve stenosis to determine their influence on outcome. Patients' age (9 +/- 9 years; range, 1 day-39 years) and a history of surgical valvotomy did not influence outcome. The number of dilating balloons (one vs. two) and balloon: annulus ratio based on the largest balloon used in each case (97 +/- 12%; range, 71-133%) did not demonstrably influence the percent reduction in valvar gradient. In contrast, with a balloon: annulus ratio greater than 100%, the incidence (26%) of significant, dilation-induced aortic regurgitation was higher than occurred when the ratio was equal to or less than 100% (11%). Fifty bicommissural and eight unicommissural valves were identified echocardiographically. Relief of obstruction was associated with apparent commissural division in 24 of 32 patients with suitable postdilation studies. The sites of fusion and stenosis relief did not influence percent reduction in valvar gradient. Substantial increases in aortic regurgitation (greater than three of five grades) occurred in three of eight unicommissural and one of 50 bicommissural valves. The presence of a thick valve was associated with a slightly lower gradient reduction (53 +/- 12%) than thin and pliant valves (63 +/- 24%) (p greater than 0.05). Unlike all other congenital lesions we have studied, dilation technique and balloon size appeared to have a lesser influence on percent reduction in valvar gradient in congenital aortic stenosis, although balloon: annulus ratio influences the increase in aortic regurgitation. Valve morphology appears to assist with predicting the outcome of dilation.

Adolescent↗
PubMed1988

Transcatheter closure of ventricular septal defects.

Between January and October, 1987, we attempted percutaneous transcatheter closure of seven ventricular septal defects (VSD) in six patients; none of the patients was a candidate for operative management. Patients' ages ranged from 8 months to 82 years (6.0-70 kg); diagnoses included postinfarction VSD (n = 4), congenital VSD (n = 1), and postoperative congenital VSD (n = 2). Indications for VSD closure were shock or respiratory failure (n = 5) or multiple episodes of endocarditis (n = 1). Closure was attempted with a Rashkind double umbrella: VSDs were crossed via the left ventricle and a guide wire was advanced to the right heart, snared with a venous catheter, and used to direct a long sheath (and ultimately the double umbrella) across the VSD. We crossed the VSD in all seven attempts, and a 17-mm double umbrella was successfully placed in each VSD. In the first (postinfarction) patient with the largest (12 mm) VSD, the umbrella embolized after 20 seconds to the pulmonary artery (without reducing flow). The other six umbrellas remained in position, either diminishing or abolishing the left-to-right shunts. Postinfarction patients had increasing VSD shunting over the next several days and died; at postmortem, the umbrellas remained well positioned in the septum, with other VSDs present. All three congenital VSDs had absent or diminished shunts after umbrella closure. These preliminary data indicate that transcatheter VSD closure is feasible in selected cases.

Angiography↗