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Biomedical subjects

J E Lock

Publications and source records attributed to J E Lock.

At least 73 records · Page 4Linked to original sources
PubMed1993

Generalized arteriopathy in Williams syndrome: an intravascular ultrasound study.

OBJECTIVES: We used intraluminal ultrasound imaging to provide additional information about the vascular pathology in Williams syndrome. BACKGROUND: The cardiovascular pathology of Williams syndrome consists of medial hypertrophy in both systemic and pulmonary arteries, which results in lumen narrowing. METHODS: Systemic and pulmonary arteries were examined in vivo using intravascular ultrasound imaging (5F, 30-MHz catheter) in three children with Williams syndrome. RESULTS: All arteries exhibited severe wall thickening with secondary lumen narrowing. Balloon dilation of a branch pulmonary artery in two children resulted in a significant localized increase in lumen caliber associated with a tear in the vessel wall. CONCLUSIONS: Intravascular ultrasound imaging in patients with Williams syndrome may permit better understanding of the pathophysiology of the syndrome and a more rational approach to therapeutic interventions.

Abnormalities, Multiple↗
PubMed1993

Multipolar endocardial mapping of the right atrium during cardiac catheterization: description of a new technique.

OBJECTIVES: Using a new mapping system that allows the simultaneous acquisition of data from 25 right atrial bipolar electrodes during cardiac catheterization, we mapped normal sinus rhythm and atrial reentrant tachycardia in 24 sheep (20 to 49 kg) and 7 pigs (25 to 35 kg). BACKGROUND: Rapid, high resolution mapping during cardiac catheterization may shorten ablation procedures and permit ablation of otherwise refractory arrhythmias. METHODS: A flexible, elliptic, basket-shaped recording catheter has five spokes, each with 10 electrodes arranged as 5 bipolar pairs. Catheter shape, electrode spacing and introduction technique were modified in response to the results of experiments in the first 23 animals. In the most recent eight animals, retraction of a string attached to the distal tip distended the basket, providing safe tissue contact. Filtered (30 to 250 Hz) bipolar recordings from all 25 electrode pairs, as well as a surface electrocardiogram, were recorded and digitized at 1,000 Hz using custom software. An activation map was digitally constructed and superimposed on anteroposterior and lateral fluoroscopic catheter images. Bipolar recordings were made in normal sinus rhythm (31 animals), with adequate signals recorded from > 95% of electrode pairs. Rapid burst pacing and intentional right atrial air embolus (30 to 50 ml) induced sustained atrial reentrant tachycardia in five animals, which was also adequately recorded. RESULTS: Catheter positioning and complete atrial mapping required < 10 min after venous access in the most recent eight experiments. The catheter was left in position for up to 4 h. Postmortem evaluation revealed minor superficial abrasion of the venae cavae or right atrial endocardium in six animals and moderate abrasion in two. No other damage was observed. CONCLUSIONS: This new system may ultimately assist in mapping simple or complex atrial arrhythmias during cardiac catheterization.

Animals↗
PubMed1993

Prevalence and risk factors for aortopulmonary collateral vessels after Fontan and bidirectional Glenn procedures.

OBJECTIVES: The purpose of this study was to evaluate the prevalence of and risk factors for aortopulmonary collateral vessels in patients who have undergone a bidirectional Glenn or Fontan procedure, or both. BACKGROUND: Aortopulmonary collateral vessels are frequently observed angiographically in patients after a bidirectional Glenn or Fontan procedure. These vessels may provide a source of pulmonary blood flow competitive with anterograde cavopulmonary flow. METHODS: We performed a retrospective study of all patients (n = 196) who underwent catheterization between January 1, 1988 and February 29, 1992 (n = 268) after bidirectional Glenn or Fontan procedures and reviewed clinical, hemodynamic and angiographic phone data. RESULTS: Collateral vessels were diagnosed in 36% of patients. Patients who underwent the bidirectional Glenn procedure were more likely to have collateral vessels than patients who underwent the Fontan procedure (65% vs. 30%, respectively; p < 0.0001). Patients with a history of a Blalock-Taussig shunt were more likely to have collateral vessels than those without (50% vs. 24%, respectively; p = 0.0006). Discretely identifiable collateral vessels were measurable in 54 (20%) of 268 catheterizations. The total estimated cross-sectional area of these vessels averaged 10.7 +/- 7.2 mm2. In patients who underwent the bidirectional Glenn procedure, a step-up in oxygen saturation from the superior vena cava to the distal pulmonary arteries or an upper lobe filling defect, or both, on pulmonary angiogram predicted total estimated cross-sectional area of collateral vessels. Most collateral vessels originated from the internal mammary arteries (34%) and the thyrocervical trunks (22%). Only 9% of collateral vessels arising from the brachiocephalic vessels were visualized by aortogram; the remainder required selective angiography in the subclavian or more distal arteries. CONCLUSIONS: Aortopulmonary collateral vessels are common after bidirectional Glenn and Fontan procedures. Aortograms often fail to diagnose their presence. The left to right shunt carried by these vessels is associated with a step-up in oxygen saturation in the distal pulmonary arteries. The clinical significance and indications for closure of these vessels are not known.

Adolescent↗
PubMed1993

Reliability of Doppler color flow mapping in the identification and localization of multiple ventricular septal defects.

The purpose of this study was to compare Doppler color flow mapping with angiography and surgical observation for detection of multiple ventricular septal defects (VSDs). Only patients with elevated pulmonary ventricular pressure were included. Among 137 patients with VSDs, 38 multiple defects were identified in 25 patients echocardiographically, 34 multiple defects in 24 patients angiographically, and 21 multiple defects in 17 patients surgically. Using surgical observation as the reference standard, the sensitivity of echocardiography for identifying patients with multiple VSDs was 17 of 17 (100%) and for angiography 15 of 17 (88%). The sensitivity of echocardiography for identifying all multiple VSDs seen at operation was 19 of 21 (90%) and of angiography was also 19 of 21 (90%). In many patients, use of both techniques may no longer be necessary.

Angiography↗
PubMed1993

Implantation and intermediate-term follow-up of stents in congenital heart disease.

BACKGROUND: Balloon-expandable stents (Johnson and Johnson Interventional Systems) have been in use for congenital heart disease since late 1989. They have made possible treatment in previously untreatable branch pulmonary artery stenoses and systemic venous stenosis. The purpose of this report is to detail the results and intermediate-term follow-up of stents used for treatment of congenital heart disease. METHODS AND RESULTS: Eighty-five patients underwent placement of 121 stents in Houston and Boston. Fifty-eight patients had stents put in pulmonary arteries, nine had stents in conduits or outflow tracts, and 21 had stents in venous stenoses or narrowed Fontan anastomoses. (Three patients had stents in two locations.) These stent procedures resulted in gradient reduction from 55.2 +/- 33.3 to 14.2 +/- 13.5 mm Hg in pulmonary arteries, from 41.4 +/- 26.0 to 20.7 +/- 17.0 mm Hg in conduits or outflow tracts, and from 9.8 +/- 6.9 to 2.4 +/- 3.1 mm Hg in venous stenoses or Fontan anastomoses. Diameter of narrowings increased from 4.6 +/- 2.3 to 11.3 +/- 3.2 mm in the pulmonary artery, from 8.8 +/- 3.6 to 12.7 +/- 2.6 in conduits, and from 3.8 +/- 2.9 to 11.3 +/- 2.8 in venous stenoses. Follow-up has shown stent fracture in one patient, restenosis in one, and sudden death in one. Recatheterization has been done in 38 patients an average of 8.6 months after stent installation. Compared with immediately postimplant data, there was no significant change in luminal diameter or pressure gradient. Redilation was performed in 14 patients (17 stents) 1 week to 24 months after implantation (mean, 10.2 months), with a small but significant increase in stenosis diameter. CONCLUSIONS: We conclude that stent treatment of vascular stenoses in congenital heart disease retains efficacy at medium-term follow-up and offers a much-improved outlook for patients with these lesions.

Adolescent↗
PubMed1993

Tetralogy of Fallot with pulmonary atresia. Rehabilitation of diminutive pulmonary arteries.

BACKGROUND: Patients with tetralogy of Fallot, pulmonary atresia, and diminutive pulmonary arteries are a high-risk group for whom there is no consensus on the correct approach to medical management. The purpose of this report is to review a 14-year experience in the treatment of these patients comparing management schemes. METHODS AND RESULTS: Between January 1978 and August 1988, 91 patients with tetralogy of Fallot and pulmonary atresia had an adequate evaluation of their pulmonary artery anatomy before any surgical management. Forty-eight of these patients had diminutive pulmonary arteries (38 to 104 mm2/m2) supplied by aortopulmonary collaterals and were managed in four different fashions. Of the 9 patients repaired primarily, 7 died early and the two survivors had poor hemodynamic outcome. Of the 9 patients conservatively managed with no intervention before 5 years of age, 4 died and only 1 had a satisfactory hemodynamic result after repair. Of 10 shunted patients, 3 died and 3 had satisfactory repairs. Since 1984, we have rehabilitated pulmonary arteries with (1) right ventricle to pulmonary artery surgical graft, (2) balloon dilation of residual pulmonary artery stenoses and embolization of collaterals, and (3) surgical closure of ventricular septal defect and repair of remaining obstructions. Of 20 patients so managed, 7 died after various stages, but 10 of 20 had complete repairs. All repaired patients with subsystemic right ventricular pressures had at least one successful pulmonary artery dilation. CONCLUSIONS: A combined catheter-surgery approach begun at an early age in patients with tetralogy of Fallot and pulmonary atresia with diminutive pulmonary arteries appears to enhance the chances of satisfactory complete repair.

Angioplasty, Balloon↗
PubMed1993

Influence of right heart size on outcome in pulmonary atresia with intact ventricular septum.

BACKGROUND: Neonates with pulmonary atresia and intact ventricular septum (PA-IVS) are frequently born with hypoplastic right heart structures that must grow after right ventricular decompression (RVD) procedures for a complete two-ventricle physiology to be achieved. Previous authors have asserted that neonatal right heart size or morphology will predict right heart growth potential. Since 1983, our bias has favored early RVD regardless of initial right heart size. In 1986, we recognized a subset of patients with coronary artery abnormalities associated with poor outcome after RVD and have defined these patients as having a right ventricular-dependent coronary circulation (RVDCC). METHODS AND RESULTS: To assess the influence of right heart size on outcome independent of the presence of RVDCC, we measured echocardiographic right ventricular (RV) dimensions in 37 neonates with adequate studies presenting between 1983 and 1990. Coronary artery anatomy was adequately assessed by angiography in 36. RV volume and tricuspid valve (TV) diameter were significantly smaller in patients with RVDCC than in those without. However, there was no statistically significant association between RV volume or TV diameter and survival among patients with or without RVDCC: Among 29 patients without RVDCC, 23 of 24 (95.8%) who achieved RVD are alive compared with 1 of 5 (20%) who did not achieve RVD (P = .001). Twenty-one of the 23 survivors have a complete two-ventricle physiology with low right atrial pressure. Among 7 patients with RVDCC, 2 patients who underwent RVD died early of left ventricular failure, whereas 4 of 5 who did not undergo RVD have survived single ventricular palliation. CONCLUSIONS: Small right heart size is associated with RVDCC but is not associated with survival in PA-IVS. Patients without RVDCC have improved survival after RVD regardless of neonatal right heart size.

Blood Volume↗
PubMed1993

Early bidirectional cavopulmonary shunt in young infants. Postoperative course and early results.

BACKGROUND: Despite the recent wide applicability of the bidirectional cavopulmonary shunt, there is limited reported experience in performing these shunts in infants 6 months or younger. METHODS AND RESULTS: Before October 1992, 17 consecutive infants aged 4.2 to 6.5 months (median, 6.1 months) underwent bidirectional cavopulmonary shunts. The diagnoses were hypoplastic left heart syndrome (n = 7), single right ventricle (n = 5), and single left ventricle (n = 5). All but 2 patients had prior palliative surgery. The bidirectional cavopulmonary shunt was performed early on an elective basis in 9 patients; the remaining patients had progressive cyanosis (6 patients), severe ventricular failure (1 patient), and coexisting restrictive bulboventricular foramen (1 patient). The median preoperative pulmonary arterial pressure and pulmonary vascular resistance were 15 mm Hg and 2.3 U.m2, respectively. One patient died; the overall hospital survival was 94%. The most common postoperative problem was transient systemic hypertension, observed in 14 (88%) of 16 survivors. Systemic arterial oxygen saturation increased from a median of 75% before surgery to a median of 85% after surgery (P < .05). The median hospital stay was 6 days. There were no late deaths during follow-up (median, 12.4 months). At postoperative cardiac catheterization performed in 9 of 16 survivors, there was no evidence of severe hypoxemia, shunt narrowing, or pulmonary arteriovenous fistulas. Of the 16 survivors, 6 have had a subsequent Fontan operation at a median age of 1.9 years; there were 5 survivors. CONCLUSIONS: Early bidirectional cavopulmonary shunt in young infants has shown encouraging early results and provides improved oxygenation with low morbidity and mortality. We speculate that an early bidirectional cavopulmonary shunt on an elective basis may reduce the deleterious sequelae of chronic hypoxemia, long-term ventricular volume overload, and repeated palliative procedures, thus yielding a more suitable Fontan candidate.

Arteriovenous Shunt, Surgical↗
PubMed1993

Intraoperative device closure of ventricular septal defects.

BACKGROUND: Surgical repair of muscular ventricular septal defects (VSDs) has been associated with significant morbidity and mortality when the defects are multiple, associated with complex cardiac lesions, or requiring left ventriculotomy. Transcatheter VSD closure may be difficult in patients weighing less than 7 kg or those with limited vascular access. We attempted intraoperative device closure of muscular VSDs during surgical repair of associated lesions. METHODS AND RESULTS: We considered intraoperative umbrella closure in 10 patients, 8 with additional complex heart lesions. "Swiss cheese" defects were present in 4. Median patient age was 4.7 months. Device closure was not attempted in 1 patient due to an inadequate septal rim. Nine umbrellas, 12 to 40 mm in diameter, were positioned to straddle the septum in all 9 patients. There were 3 early deaths, 2 in patients who were moribund preoperatively. The third was due to severe ventricular dysfunction. Among the 6 survivors, 3 had a Qp:Qs < or = 2 and right ventricular or pulmonary artery pressure less than half systemic. These patients had no further intervention. The other 3 had a Qp:Qs > 2. One died unexpectedly 5 weeks after cardiac surgery. The other 2 had subsequent closure of residual VSDs. All 5 survivors are well at follow-up of 8 to 25 months. CONCLUSIONS: Intraoperative umbrella VSD closure appears less successful than VSD closure in the catheterization laboratory. In selected patients, particularly very small infants, intraoperative device placement may be advantageous. Completeness of closure is difficult to assess intraoperatively.

Cardiac Catheterization↗
PubMed1993

Interventional catheter procedures used in congenital heart disease.

Many of the transcatheter devices described in this article remain investigational in the United States. Currently, we consider the applications of these techniques as either (1) procedures of choice (for closures of patent ductus arteriosus, balloon dilation or stent implantation for peripheral pulmonary stenoses, balloon dilation of recurrent or persistent aortic coarctation, balloon pulmonary valvotomy, closure of congenital muscular or postoperative residual ventricular septal defects, closure of patent foramen ovale in the setting of cyanosis, balloon aortic valvotomy, fenestration closures, coil embolization of thoracic collateral vessels); (2) effective alternatives to surgical therapy (closures of atrial septal defects of the secundum type, balloon dilation of native aortic coarctation, stent implantation for conduit or baffle obstruction, device emobolization of paravalvular leaks or coronary artery fistulas); or (3) treatments with unproven effect (closure of acute postmyocardial infarction ventricular septal defects, closure of patent foramen ovale for idiopathic stroke, stent implantation for pulmonary venous stenosis) (Table 1). Patients with congenital heart disease often undergo multiple catheterizations and surgical therapies, each with its own complications and sequelae. Clinical trials of catheter-based technologies for patients with congenital heart disease have consisted of uncontrolled case series with a lack of standardized follow-up. Additional prospective large-scale clinical trials of these therapies seem necessary before their widespread acceptance.

Cardiac Catheterization↗
PubMed1993

Transcatheter closure of atrial and ventricular septal defects.

The clamshell double umbrella (Bard Clamshell Septal Umbrella, USCI Division, C. R. Bard, Billerica, MA) was developed to allow closure of septal defects, both atrial and ventricular. The device and delivery system and the techniques for implanting the device in atrial and ventricular defects are described in detail. Although fractures of the arms supporting the umbrellas in some patients have lead to modification of the device, the early experience in clinical trails are encouraging.

Cardiac Catheterization↗
PubMed1992

Transcatheter umbrella closure of valvular and paravalvular leaks.

OBJECTIVES: Our aim was to adapt the technique of transcatheter umbrella closure of intracardiac defects for closure of valvular and paravalvular defects. BACKGROUND: The double-umbrella device developed by Rashkind and Cuaso has been safely and effectively delivered across a host of intracardiac defects, but transcatheter closure of valvular and paravalvular leaks has not been reported. METHODS: Between February 1987 and September 1990, eight patients who were believed to be poor operative candidates were taken to the catheterization laboratory for transcatheter double-umbrella closure of a valvular or a paravalvular leak. Four patients had a paravalvular leak around a prosthetic aortic valve. The other four patients had a valvular leak: one patient with a regurgitant native aortic valve after a Stansel procedure and three patients with a regurgitant porcine valve in a left ventricular apex to descending aorta conduit. RESULTS: Placement of a double-umbrella device was attempted in seven of the eight patients and was successful in all seven. Device placement was not attempted in one patient because of the crescentic shape of his defect. Two patients required two devices for each closure; the other five required only one device each. Angiography, performed on six patients after device closure, demonstrated that three patients had a completely occluded defect, two had trivial residual flow and one patient had mild residual flow through the device. All significant complications occurred in one patient who had hemolysis and oliguria that resolved when the initial umbrella was replaced by a larger device. In addition, two devices migrated to the patient's pulmonary arteries but were retrieved in the catheterization laboratory without difficulty. No other early or late complications occurred in 21 to 50 months of follow-up. Of the four patients with a paravalvular leak, the one who did not receive a device died at operation, one patient died at operation for an associated defect (in the operating room the umbrella was found securely in place across the paraaortic defect) and two patients are clinically well at home after 21 and 32 months, respectively. Of the four patients with closure of a valvular leak, one patient remains well at home 50 months later, one patient died at operation for associated defects and two patients had additional successful surgical treatment and remain well 29 months after device placement. CONCLUSIONS: Transcatheter umbrella closure appears to be a reasonable alternative for closure of a valvular or paravalvular leak in patients who are poor operative candidates.

Aortic Valve↗
PubMed1992

Front-loading of double-umbrella devices, a new technique for umbrella delivery for closing cardiovascular defects.

In all, 22 defects (6 atrial septal, 13 ventricular septal, 2 patent ductus arteriosus and 1 coronary artery fistula) in 17 patients were closed with double umbrella using a new delivery technique, front-loading. The umbrella was loaded in the sheath outside the body and then advanced with-out use of the rigid pod to the defect. The defect was successfully closed in all 17 patients, including 5 in whom standard delivery techniques were unsuccessful. Front-loading enables the double umbrella to be delivered through a smaller long sheath than does the standard technique, and enables the flexible umbrella rather than the rigid pod to be advanced through curves in the sheath, and may improve delivery of double-umbrella devices to inaccessible parts of the circulation.

Adolescent↗
PubMed1992

Transcatheter closure of coronary artery fistulas.

Transcatheter closure of a coronary artery fistula was undertaken in nine patients. There were three fistulas from the left circumflex coronary artery to the coronary sinus, three from the left anterior descending coronary artery to the right ventricular apex, two from the right coronary artery to the superior vena cava/right atrial junction and one fistula from the left circumflex artery to the pulmonary artery. The fistula was closed with Gianturco coils in six patients, a double-umbrella device in two and a combination of an umbrella and coils in one patient. All fistulas are completely occluded. Complications consisted of migration of two coils, one of which was retrieved, and a transient junctional tachycardia in one patient. In an additional three patients with multiple coronary artery fistulas, transcatheter occlusion was not attempted.

Adolescent↗
PubMed1992

Transcatheter ablation of ectopic atrial tachycardia in young patients using radiofrequency current.

BACKGROUND: Ectopic atrial tachycardia (EAT) is a reversible cause of cardiomyopathy but may be quite difficult to control with conventional therapy. Transcatheter ablation with radiofrequency current was tested as an alternative to medical or surgical treatment of this condition. METHODS AND RESULTS: Twelve young patients (aged 10 months to 19 years) with drug-resistant EAT were treated with direct transcatheter ablation of the ectopic focus using radiofrequency (RF) energy. All had depressed left ventricular contractility by echocardiographic criteria, involving shortening fractions of 10-26% (median, 20%; normal, 28-35%). The EAT was mapped to the left atrium in seven cases and to the right atrium in five. Local atrial activation at the ectopic site preceded the onset of the surface P wave by 20-60 msec (median, 42 msec). Tachycardia terminated 0.5-13.0 seconds (median, 2.0 seconds) into a successful RF application. The ablation effectively eliminated EAT in 11 of 12 patients (92%), all of whom were discharged in sinus rhythm without medications after a median hospital stay of 48 hours. Ablation was unsuccessful in one patient with diffuse dysplasia of the anterior right atrium, who eventually did well after surgical resection of abnormal atrial tissue. Transient depression of sinus node function was noted in one patient who had successful ablation of an EAT focus in close proximity to the sinus node, although normal sinus node function returned within 72 hours. No other complications were encountered. During follow-up (3-21 months; median, 13 months), one patient had recurrence of a slower and less-sustained EAT that was successfully eliminated at a second ablation session. All others remained in sinus rhythm, and all 12 subjects recovered normal ventricular function. CONCLUSIONS: RF ablation appears to be a safe and effective therapeutic option for drug-resistant ectopic atrial tachycardia and may be the preferred first-line therapy for those patients with depressed ventricular function.

Adolescent↗
PubMed1992

Diagnosis and management of right ventricle-dependent coronary circulation in pulmonary atresia with intact ventricular septum.

BACKGROUND: Coronary artery anomalies including 1) right ventricle (RV)-to-coronary artery fistulas, 2) coronary artery stenoses, and 3) coronary occlusions occur in patients with pulmonary atresia with intact ventricular septum (PA-IVS). In some, a large part of the coronary blood supply may depend on the RV. This RV-dependent coronary circulation may determine survival after right ventricular decompression (RVD): RVD may cause RV "steal" in the presence of fistulas alone and ischemia, coronary isolation, or myocardial infarction in the presence of coronary stenoses. METHODS AND RESULTS: Eighty-two patients with PA-IVS who presented between January 1979 and January 1990 were reviewed; 26 (32%) had RV-to-coronary artery fistulas. Of these 26, 23 had adequate preoperative coronary angiograms for analysis. RVD was achieved in 16. Seven of 16 had fistulas only; each survived RVD. Six of 16 had stenosis of a single coronary artery [left anterior descending coronary artery (LAD), four; right coronary artery (RCA), two]; four of six survived RVD. Three of 16 had stenoses and/or occlusion of both the RCA and LAD; all three died shortly after RVD of acute left ventricular dysfunction. CONCLUSIONS: 1) Potential RV steal alone does not preclude successful RVD. 2) Fistulas with stenoses to a single coronary artery may not preclude successful RVD. 3) RVD appears to be contraindicated in the presence of stenoses and/or occlusion involving both the right and left coronary systems. Nonsurvival after RVD seems to depend on the amount of the left ventricular myocardium at risk, i.e., that which is distal to coronary artery stenoses, especially when involvement of both coronary arteries limits effective collateralization. Precise definition of coronary arterial anatomy is mandatory in neonates with PA-IVS.

Arteriovenous Fistula↗