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Biomedical subjects

R B Mee

Publications and source records attributed to R B Mee.

At least 37 records · Page 2Linked to original sources
PubMed1996

Clinicopathologic findings in congenital aneurysms of the great vessels.

We describe the clinical, histopathologic, and angiographic findings in four children with congenital abnormalities of the great vessels of unknown cause, comprising either single or multiple arterial aneurysms, aortic/arterial dilatation, vessel tortuosity, or combinations of these abnormalities. Two children had early and severe respiratory distress due to aneurysmal compression of the trachea. All children had diffuse dilatation of several arteries, and two children also had tortuosity of multiple arteries. Progression of these abnormalities was clearly evident in one child, in whom diffuse vessel irregularity and tortuosity affected intra-abdominal, and intra and extra-cranial arteries. One child died at 5 years, while the other three have undergone successful surgical repair in the first 3 months of life and are now well, between age 2.5 and 7 years. The phenotype of each child appears unique but all have in common the rare finding of aneurysms of the aorta and main pulmonary artery. Congenital aortic aneurysms did not occur as an isolated finding in any of these children.

Abnormalities, Multiple↗
PubMed1996

Surgical commissurotomy of the aortic valve: outcome of open valvotomy in neonates with critical aortic stenosis.

Early intervention is necessary in neonates with critical aortic stenosis. The advent of alternate therapy, particularly balloon aortic valvuloplasty, requires a reappraisal of the traditional surgical approach, including the efficacy of initial transvalvar gradient reduction and freedom from recurrence of obstruction in the longer term. This report describes a series of 33 consecutive infants who underwent surgical aortic valvotomy in the first month of life. The hospital mortality was 18 percent with a 5-year probability of survival of 66 percent (90 percent CI, 50 percent to 79 percent). Fourteen reinterventions, nine reoperations and five balloon dilatations, were required at a median age of 0.8 years (range 9 days to 6 years). Three patients died after reintervention (one early and two late). The median follow-up time was 5.8 years (range 0.2 to 14 years). At last follow-up Doppler investigation the average Doppler mean and peak gradients were 34 mm Hg and 18 mm Hg, respectively. Open valvotomy in neonatal aortic valve stenosis allows the use of an appropriate surgical approach with low initial mortality and satisfactory 5-year freedom from reintervention.

Aortic Valve Stenosis↗
PubMed1996

Accuracy of pulse oximetry in hypothermic neonates and infants undergoing cardiac surgery.

OBJECTIVES: To assess the accuracy of pulse oximetry under hypothermic conditions in neonates and infants undergoing cardiac surgery, and to assess the effect of probe site as well as probe site skin temperature on the reliability of pulse oximetry. DESIGN: Prospective Study. SETTING: Cardiac operating room and intensive care unit of children's hospital. PATIENTS: Twenty-five infants <3 months of age undergoing cardiac surgery with cardiopulmonary bypass. INTERVENTIONS: Pulse oximeter readings (Sp O2) from probes placed on the hand and foot were recorded at various skin temperatures and compared with hemoximeter oxygen saturations (Sa O2) obtained on simultaneously drawn arterial blood samples. Core temperature, arterial pressure and vasodilator use were recorded simultaneously. MEASUREMENTS AND MAIN RESULTS: Pulse oximetry bias (Sp O2 - Sa O2) increased to an unacceptable range (>+3% or <-3%) in 45.5% of the readings at foot probe site temperatures of <27 degrees. Pulse oximetry bias was within an acceptable range in 94.7% of the readings at temperatures >29 degrees. There was no significant difference between oximeter readings obtained from two probe sites (hand and foot). Administration of phenoxybenzamine improved the accuracy of pulse oximetry in ten infants at skin temperature of <27 degrees. CONCLUSIONS: Pulse oximetry readings in small infants are likely to be unreliable at skin temperatures of <27 degrees, irrespective of probe site. Intravenous phenoxybenzamine appeared to improve the accuracy of pulse oximetry at low temperatures.

Age Factors↗
PubMed1995

Surgical repair of severe bilateral branch pulmonary artery stenosis.

Management options for severe, bilateral branch pulmonary artery stenosis include percutaneous balloon dilation and direct surgical correction. Results with both balloon angioplasty and operation have been somewhat unpredictable. We report a case of staged surgical correction involving bilateral branch pulmonary artery reconstruction.

Anastomosis, Surgical↗
PubMed1995

A cure for pulmonary arteriovenous fistulas?

Diffuse bilateral pulmonary arteriovenous fistulas developed in a cyanotic child with left atrial isomerism, consisting of an interrupted inferior vena cava with continuation of the hemiazygos vein to the isolated left superior vena cava, soon after she underwent a Kawashima operation that left the hepatic veins draining into the common atrium. The fistulas regressed after the hepatic veins were connected to the confluent pulmonary arteries with a left lateral atrial tunnel.

Arteriovenous Fistula↗
PubMed1995

Modified Norwood procedure for hypoplastic left heart syndrome.

BACKGROUND: Since June 1994, we have used a modification of the Norwood technique in 13 patients presenting with the hypoplastic left heart syndrome or similar variants. METHODS: This technique involves coarctation repair, arch reconstruction, and creation of a neo-ascending aorta using autologous great vessel tissue only. Pulmonary blood flow is provided by a central shunt of 3.0- to 4.0-mm Gore-Tex. RESULTS: The mean age and weight at operation were 15 days (range, 1 to 77 days) and 3.2 kg (range, 1.7 to 4.6 kg), respectively. The mean circulatory arrest time was 32 minutes (range, 25 to 50 minutes). There was one operative death, and there have been no late deaths. Seven patients have gone on to conversion to a bidirectional cavopulmonary shunt at a mean age of 6 months. There have been no cases of recurrent coarctation, arch obstruction, or left pulmonary artery stenosis. Significant coronary insufficiency requiring revision of the ascending aortic reconstruction has developed in 2 patients. CONCLUSIONS: We believe this approach offers the advantage of using the patient's own native tissue for all great vessel reconstruction. This technique may also allow 10 to 15 minutes less of circulatory arrest time. The theoretic benefits include improved growth of repaired structures and avoidance of homograft or prosthetic material. The long-term results remain to be elucidated.

Cardiac Catheterization↗
PubMed1994

Can a dilated coronary sinus produce left ventricular inflow obstruction? An unrecognized entity.

Drainage of a persistent left superior vena cava to the coronary sinus is a common congenital lesion associated with dilatation of the coronary sinus. We report on 4 cases in which marked enlargement of the coronary sinus was present, immediately superior to and partially occluding the mitral valve, with consequent obstruction to left ventricular inflow. In 1 patient, presenting with cardiac failure in early infancy, this abnormality was the major defect, mimicking the features of cor triatriatum, and surgical correction led to significant symptomatic improvement. In 3 other patients this abnormality was associated with other congenital lesions, and it is postulated that in these cases impairment of flow into the left ventricle in the presence of an atrial septal defect elevated the left atrial pressure and increased the shunt across the atrial septum, thereby increasing the symptoms and clinical findings. Surgical reduction of the enlarged coronary sinus was performed in each case through the interatrial septum, and the technique is described.

Cardiomegaly↗
PubMed1994

Arterial switch: translocation of the intramural coronary artery.

Translocation of an intramural coronary artery is one of the most challenging problems in anatomic correction of transposition of the great arteries. Of 259 patients undergoing arterial switch procedure for transposition of the great arteries in our hospital, 12 (4.6%) were found to have intramural coronary arteries. The diagnosis was made intraoperatively in all patients. There were five different types of intramural coronary anatomy noted, with ostial stenosis present in half. The operative technique consisted of detachment of the posterior commissure of the aortic valve and unroofing of the intramural segment of the coronary artery by excision of a triangular portion of internal aortic wall. The coronary arteries were excised as a single disc, which was divided into two cuffs. The arterial switch was then performed in the usual fashion. The posterior commissure of the aortic valve was resuspended to the pericardial patch used to reconstruct the neopulmonary artery sinus. There were no operative or late deaths over a follow-up of 328 patient-months. Postoperatively, no patient showed ischemic changes on electrocardiogram or abnormal wall motion on echocardiogram. We believe that intramural coronary arteries can be managed satisfactorily with this technique, and that arterial switch will be possible in all cases.

Coronary Vessel Anomalies↗
PubMed1994

Repair of insufficient bicuspid aortic valves.

A technique for the repair of bicuspid aortic valves that includes resection of the flail segment of the prolapsing leaflet, annuloplasty, and resection of the raphe, when present, has been reported. To assess the efficacy of this technique in the repair of insufficient bicuspid aortic valves, the results in 72 consecutive patients were assessed. The mean age of the patients was 39 +/- 11 years; 94% were male. Fifty-six patients (78%) underwent isolated aortic valve repair, 9 (12.5%) underwent aortic and mitral valve repair, and 7 (9.7%) had other associated procedures. All patients underwent leaflet resection, including 35 (48%) at the raphe. The mean aortic occlusion time was 39 +/- 12 minutes. There were no operative deaths. The severity of aortic insufficiency, as assessed by Doppler echocardiography (graded from 0 to 4) preoperatively and intraoperatively and at late follow-up, was 3.6 +/- 0.6, 0.4 +/- 0.4, and 0.9 +/- 0.8, respectively, with a p value of < 0.0001 for the latter two values versus the preoperative one. There have been no postoperative deaths. Patients did not receive anticoagulation treatment and there were no strokes or episodes of endocarditis. Six patients have required reoperation; 3 underwent repeat repair. The Kaplan-Meier freedom from aortic valve reoperation probabilities at 12 and 24 months were 94% and 89.5%, respectively. We conclude that valvuloplasty for insufficient bicuspid aortic valves is technically safe, is associated with a low incidence of recurrent insufficiency, and has been associated with no other valve-related complications.

Actuarial Analysis↗
PubMed1994

Surgical management of Marfan syndrome in children.

Between August 1983 and January 1991, seven patients with Marfan syndrome underwent surgery for severe cardiovascular complications. The mean age at presentation was 5.7 months (range 4 to 9 months) in the infant group (n = 3), and 13.3 years (range 10 to 16 years) in a group of older children (n = 4). The primary indications for surgery in the infant group (performed at a mean of 3 years after diagnosis) were ascending aortic aneurysm with valvar regurgitation in one patient, and severe mitral valve prolapse with regurgitation in two. In the older group, surgical indications (performed at a mean of 2.8 years after diagnosis) were ascending aortic aneurysm with valvar regurgitation in three patients and acute aortic dissection in one. For aortic surgery, a composite valved conduit was used in four patients, and an aortic homograft in one. For mitral valve surgery, mechanical prostheses were used. All patients survived the primary operation. Over a mean follow-up of 17.5 patient-years (range 1 to 9 years), two patients in the infant Marfan group went on to further successful surgery (prosthetic mitral valve replacement and aortic root repair with aortic homograft) at a mean interval of 4.3 years after the initial surgery. Our results suggest that the major cardiovascular risk factors of Marfan syndrome in the young, even in those diagnosed during infancy, have been favorably changed by surgery with an encouraging medium-term outlook. The correct timing of surgery is aided by echocardiography.

Adolescent↗
PubMed1994

Bloodless open-heart surgery in infants and children.

Between October 1984 and January 1993, seven children of Jehovah's Witnesses underwent corrective open-heart surgery for congenital defects, on cardiopulmonary bypass (CPB). Age at surgery ranged from three months to 6.5 years, and weight ranged from 4.2 kg to 23.2 kg, with two children weighing less than 10 kg. The principal cardiac anomalies were tetralogy of Fallot (two), double outlet right ventricle (one), subaortic stenosis (one), transposition of the great arteries and ventricular septal defect (one), atrial septal defect and congenital heart block (one), and congenital mitral regurgitation (one). Hypothermic CPB was used in all seven operations with crystalloid priming of the extracorporeal circuit. CPB was based on our standard perfusion protocols. All surgical procedures were done without the use of blood or blood products. The mean preoperative haematocrit (Hct) was 40.9% (range 31.0-47.8%). The mean lowest intraoperative Hct was 17.3% (range 15.0-24.3%), whereas the immediate post-CPB Hct was 19.6% (range 15.3-24.0%). The Hct progressively increased to 29.2% (range 21.0-34.2%) on the first postoperative day, and 32.3% (range 24.2-38.3%) at the time of discharge. There was no hospital mortality, and the mean hospital stay was 10 days (8-13 days). We report the safe repair of complex open-heart surgery in children, without blood transfusion, even in small infants. The successful management of these patients requires meticulous attention to surgical and perfusion technique, and sound postoperative management.

Blood Transfusion↗
PubMed1993

Staged conversion to arterial switch for late failure of the systemic right ventricle.

Late failure of the systemic right ventricle is seen in up to 10% of patients after atrial switch for transposition of the great arteries and in patients with atrioventricular and ventriculoarterial discordance. Since 1981, 24 such patients have entered a program to achieve conversion to arterial switch. The primary diagnoses were transposition of the great arteries with ventricular septal defect (n = 10), transposition of the great arteries with intact ventricular septum (n = 5), Taussig-Bing anomaly (n = 4), and atrioventricular and ventriculoarterial discordance (n = 5). The mean interval from atrial switch to right ventricular failure was 7 years. Four patients underwent direct conversion to arterial switch, with one operative death. In 3 of these patients the initial left ventricular pressure was high. The fourth patient was too sick to undergo banding, and he required left ventricular assist device support after switch conversion. The other 20 patients underwent 34 procedures to place or tighten a pulmonary artery band to prepare the left ventricle to tolerate systemic pressure. There was one band-related operative death. Twelve patients have thus far gone on to switch conversion 13 days to 5 years (mean, 26 months) after banding. In total, therefore, 16 patients have had an arterial switch with atrial reconstruction. The early mortality for switch conversion was 2 of 16 (12.5%; 70% confidence limits, 4% and 27%), with one late death 12 months after operation. Including operative mortality, the 1-year actuarial survival probability after conversion was 80% (70% confidence limits, 62% and 92%). All survivors are asymptomatic.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1993

Pulmonary atresia with intact ventricular septum: surgical management based on right ventricular infundibulum.

The optimal management of infants with pulmonary atresia with intact ventricular septum (PA.IVS) remains a controversy. Attempts have been made to base the surgical approach on various geometrical or morphological characteristics of the right ventricle (RV). However, the overall results remain poor when compared to other complex congenital heart defects. Forty-eight neonates with PA.IVS were admitted to our unit between 1980 and 1992. The management plan has evolved to be based entirely on the echocardiographic assessment of the state of development of the infundibulum of the RV. In neonates with a well-formed infundibulum (n = 31), the initial palliation consisted mainly of pulmonary valvotomy (without cardiopulmonary bypass) and PTFE shunt from the left subclavian artery to the main pulmonary artery. There was one death from initial palliation in this subgroup. If necessary, the RV cavity was later enlarged by excision of the hypertrophic muscle of both the trabecular and infundibular portions, before finally attempting biventricular repair. The actuarial probability of achieving a biventricular repair at 40 months of age was 60% (95% CL = 39.5% to 71.3%). Thirteen patients have undergone biventricular repairs with one late death over a total follow-up of 1,720 patient months. In one patient, the RV failed to grow satisfactorily, necessitating a Fontan procedure. Seventeen patients without a well-formed infundibulum were approached with a Fontan procedure in mind. The initial palliation in these patients consisted of a modified Blalock-Taussig shunt only. Ten have undergone a Fontan procedure so far and five are awaiting such repairs. In this group there were four operative deaths: two after initial palliation, and two after Fontan procedures. In patients with a well-developed infundibulum, the actuarial survival probability was 93% (95% CL = 74% to 98%) at 8 months with no further late deaths over 120 months follow-up, whereas in patients without a well-formed infundibulum it was 75% at 40 months (95% CL = 46% to 89%). The overall survival probability at 104 months was 77% (95% CL = 51% to 90%).

Actuarial Analysis↗
PubMed1993

Long-term follow-up after two coronary repair of anomalous left coronary artery from the pulmonary artery.

A retrospective analysis of ten patients with anomalous left coronary artery arising from the pulmonary artery operated between 1979 and 1990 was undertaken. All presented with evidence of left ventricular dysfunction and "ischemic" mitral regurgitation. Surgical repair consisted of an aortopulmonary tunnel (Takeuchi) procedure in eight and direct left coronary artery reimplantation in two. Two patients required postoperative support with a left ventricular assist device. There were no operative or late deaths (CL 0% to 17%) for a follow-up of over 670 patient months. All patients are in New York Heart Association Class I or II, though two patients are still receiving anticongestive medications. One patient has required further surgery for pulmonary artery stenosis, and another has had a mitral valve replacement because of severe mitral regurgitation. One additional patient has moderate-to-severe residual mitral regurgitation and two have a trivial left coronary to main pulmonary artery fistula. All have a patent, nonstenotic left coronary artery and much improved left ventricular function and perfusion as assessed by echocardiography, thallium scan, gated blood pool scan, and angiography. There have been no documented arrhythmias, clinically or on Holter monitoring. The ECGs have shown resolution or improvement of the initial changes of ischemia/infarction in all patients. Chest X-rays have shown normalization of cardiothoracic ratio in eight of ten patients. Excellent early and late results can be achieved following timely surgical repair. Marked improvement in left ventricular function has been observed in patients with poor preoperative left ventricular function, even in the presence of extensive ischemia/infarction.

Child, Preschool↗