Biomedical subjects

Michael H Hines

Publications and source records attributed to Michael H Hines.

7 recordsLinked to original sources

PubMed2004

Anterior leaflet augmentation for ischemic mitral regurgitation.

BACKGROUND: Mitral valve repair improves survival and quality of life in patients with ischemic mitral regurgitation (MR). Although many repair methods exist for this condition, the ideal approach remains unknown. The purpose of this study is to describe a simple technique for repair of ischemic MR that addresses the pathophysiology of tethered leaflets and to report its early results. METHODS: The technique consists of pericardial patch enlargement of the anterior mitral leaflet and placement of a flexible annuloplasty band. Candidates for the repair had ischemic cardiomyopathy and echocardiographic evidence of moderate or severe Carpentier type IIIb MR. Patients were followed with serial echocardiography. RESULTS: Between January 2002 and November 2003, 25 adult patients underwent anterior leaflet augmentation for ischemic MR. Mean age was 64.8 +/- 10.6 years, and mean left ventricular ejection fraction was 0.36 +/- 0.14. Preoperative MR by transesophageal echocardiography was severe in 84% of patients and moderate in 16%. Annuloplasty band sizes were 27 mm to 31 mm (mean, 28.4 +/- 1.1 mm). Concomitant coronary artery bypass grafting was performed in all patients. Transesophageal echocardiography immediately after repair revealed MR to be none or trace in 80% of patients and mild in 20%. No intraoperative conversion to valve replacement was performed. In follow-up, 2 patients have experienced moderate MR and are being treated medically, and no patients have mitral stenosis. At 2 years, actuarial freedom from moderate or greater MR is 81%. CONCLUSIONS: For patients with ischemic MR, anterior leaflet augmentation is a simple and reproducible method of valve repair that addresses the pathophysiology of tethered leaflets. Early results in a small number of patients have been encouraging.

Adult↗

PubMed2004

Cavernous sinus thrombosis complicating sinusitis.

BACKGROUND: Septic cavernous sinus thrombosis is a rare complication of paranasal sinusitis. OBJECTIVE: To familiarize the clinician with the pathogenesis, diagnosis, and appropriate management of septic cavernous sinus thrombosis. DESIGN: Case report and literature review. SETTING: Pediatric intensive care unit in a university hospital. PATIENT: We present a 12-yr-old female with a 1 wk history of an upper respiratory tract infection with worsening dyspnea, cough, and swelling of the left eye progressing to adult respiratory distress syndrome. Secondary to the need for significant mechanical ventilatory support, venovenous extracorporeal membrane oxygenation was initiated. Computed tomography scan of the head and neck with contrast revealed bilateral cavernous sinus thrombosis. After broad-spectrum intravenous antibiotics and aggressive supportive care in conjunction with surgical intervention (maxillary sinus lavage and right orbital exploration) and anticoagulation therapy, the patient recovered. Blood cultures were positive for Viridans streptococcus. At discharge 3 wks later, the patient had improved, but had right-eye blindness. CONCLUSIONS: The diagnosis of septic cavernous sinus thrombosis requires a high index of suspicion and confirmation by imaging; early diagnosis and surgical drainage of the underlying primary source of infection in conjunction with long-term intravenous antibiotic therapy are critical for an optimal clinical outcome.

Anti-Bacterial Agents↗

PubMed2003

Vasomotor instability in neonates with chromosome 22q11 deletion syndrome.

Approximately 70% of individuals with chromosome 22q11 deletion syndrome (22q11DS) have congenital heart defects. A host of other vascular problems in these patients, such as tortuous carotid arteries, Raynaud's phenomenon, unexplained hypotension, hypertension, and hypothermia, raise the possibility that there may be abnormal autonomic regulation of the vascular system. So far, however, there has been no formal report of autonomic dysfunction in patients with 22q11 deletion. We present two infants with 22q11DS, who had profound hypotension after uncomplicated surgeries for congenital heart disease. The hypotension was not responsive to vasopressor treatment (and extracorporeal membrane oxygenation in one infant) and resulted in death, due to multiorgan system failure. Obvious causes, such as poor cardiac contractility, prolonged circulatory arrest, neurological abnormality, sepsis and blood loss were excluded. On autopsy, no abnormalities were found that could explain the hypotension. We hypothesize that these infants died of severe hypotension due to abnormal vascular tone and that this is a variable feature in individuals with 22q11 deletion. The autonomic nervous system, which is responsible for the regulation of vasomotor tone, may be variably affected in 22q11DS. This could have implications for the surgical management of patients with 22q11DS. Further studies on this topic would establish or refute the association between 22q11DS and dysautonomia.

Adult↗

PubMed2003

Elective extracorporeal support for complex tracheal reconstruction in neonates.

BACKGROUND: Congenital obstructive anomalies of the trachea present unique challenges in reconstruction and perioperative airway management. Complications include anastomotic breakdown, leak and granulation formation related to the complexity of the repair, and difficulties with perioperative airway management. We describe our technique of elective intraoperative and postoperative extracorporeal support to improve surgical exposure and postoperative healing. METHODS: We have performed complex tracheal reconstructions in 4 newborns (2.2 to 4.3 kg) for long segment tracheal stenosis and complete tracheal rings, diagnosed with bronchoscopy and computerized tomography. Three of the 4 infants had other significant anomalies including complex congenital heart disease, hydrocephalus, encephalomalacia, left lung agenesis, facial anomalies, vertebral anomalies, and hand and hip anomalies. The repairs were performed through a median sternotomy using an extracorporeal membrane oxygenation circuit for support. Venoarterial support was used for the sliding tracheoplasty reconstruction. Extracorporeal membrane oxygenation was converted to venovenous for postoperative "airway rest." After diuresis, the lungs were reexpanded and the 4 patients were ventilated and removed from extracorporeal membrane oxygenation at 4, 5, 8, and 9 days postoperatively. Bronchoscopy was performed to evaluate the airway. RESULTS: All patients had excellent healing of the trachea without granulation tissue. There were no complications of extracorporeal membrane oxygenation support or bleeding issues. All 4 patients survived the surgery and immediate postoperative period with 2 late deaths. The child with congenital heart disease expired after 8 weeks after having hepatorenal failure develop. The child with Goldenhar's syndrome and a single left lung died after 5 months in the hospital. The other 2 patients survived. Two of the infants required late tracheostomy for facial and laryngeal anomalies. CONCLUSIONS: Extracorporeal membrane oxygenation provides an excellent environment for complex tracheal reconstruction and promotes postoperative healing by minimizing trauma to the reconstructed airway.

Congenital Abnormalities↗

PubMed2003

Video-assisted diaphragm plication in children.

BACKGROUND: Diaphragm paralysis after cardiac surgery may be secondary to phrenic nerve injury by ice, electrocautery, or dissection. Although most are asymptomatic, some patients, particularly children, have significant respiratory compromise. Video-assisted plication may offer more rapid improvement and recovery than thoracotomy in pediatric patients. METHODS: We performed five procedures. The diaphragm was elevated, clamped, oversewn, and tacked down into the pleural gutter. The procedure was performed on 2 infants after repair of total anomalous pulmonary venous connection, on 1 child after the Fontan procedure, on 1 child after repair of tetralogy of Fallot, and on 1 child with congenital eventration. Indications included ventilator dependency, post-Fontan protein losing enteropathy with elevated venous pressures and chronic right lower lobe collapse, persistent atelectasis with recurrent pneumonias, and asymptomatic severe eventration. RESULTS: Ventilator-dependent patients were extubated after 2 and 3 days. The remaining patients were immediately extubated. One patient was discharged the day of surgery and 2 were discharged at 1 and 3 days postoperatively. The remaining 2 were discharged on postoperative day 30 and 45 after continued issues with feeding and prematurity. The child with the eventration had rapid expansion and growth of the left lung over the next few weeks with a normal chest radiograph 3 weeks later. The child with recurrent pneumonia reexpanded her left lower lobe and remains free of infection. There were no wound infections, lung or vascular injuries, or complications from the procedure. All the patients had successful flattening of the hemidiaphragm as documented by chest radiograph, with successful lung reexpansion. CONCLUSIONS: Video-assisted plication of paralyzed diaphragms is effective and safe, involves less morbidity, and has quicker recovery times than traditional open techniques.

Child, Preschool↗

PubMed2003

Video-assisted ductal ligation in premature infants.

BACKGROUND: Video-assisted thoracic surgery has been shown to be a safe and effective method of closing the patent ductus arteriosus in infants and children. We have applied this technique in low birth weight premature infants and now report our experience. METHODS: Since 1996, we have used video-assisted thoracic surgery ligation as the treatment of choice for all patent ductus arteriosus, including 100 performed on premature infants (23 to 31 weeks' gestation, mean 25.6 weeks; 0.420 to 1.5 kg, mean 0.859 kg). A modification of our previously described technique was used with a three-port approach. All patients had some degree of symptoms of congestive failure with failure to wean from ventilatory support or oxygen dependency. Five infants had associated patent foramen, and 1 had a small ventricular septal defect. RESULTS: All 100 procedures were performed in the operating room. One infant was found to have a coarctation, and the procedure was aborted. The remaining 99 were successfully ligated, although three were converted to an open procedure (3%) because of coagulopathy, poor pulmonary compliance, or hemodynamic instability. There were no procedure-related deaths; however, 15 infants subsequently died of complications of prematurity, including enterocolitis, sepsis, and late respiratory failure. Six infants had chest tubes left in place for coagulopathy, effusions, suspected air leak, and existing empyema. There were six residual pneumothoraces, four requiring treatment. CONCLUSIONS: Video-assisted thoracic surgery is a safe and effective technique for patent ductus arteriosus ligation in premature infants, including those with very low and extremely low birth weight.

Cohort Studies↗

PubMed2002

The pharmacokinetics of epsilon-aminocaproic acid in children undergoing surgical repair of congenital heart defects.

UNLABELLED: epsilon-Aminocaproic acid (epsilonACA) is often administered to children undergoing cardiac surgery by using empiric dosing techniques. We hypothesized that children would have different pharmacokinetic variables and require a dosing scheme different from adults to maintain stable and effective serum epsilonACA concentrations. Eight patients were enrolled in our study. epsilonACA 50 mg/kg was administered three times IV: before, during, and after cardiopulmonary bypass (CPB). Nine serum samples were obtained. epsilonACA plasma concentrations were measured by using high-performance liquid chromatography, and pharmacokinetic modeling was done by using NONMEM. The best fit was seen with a two-compartment model with volume of distribution (V(1)) adjusted for weight and CPB. Compared with published results in adults, modeling suggests that weight-adjusted V(1) is larger in children than in adults before, during, and after CPB. Clearance from the central compartment (k(10)) was also greater in children than adults, and declined during CPB. Redistribution rates from the central compartment, k(12) and k(21), were greater in children and not affected by CPB. We modeled several different dosing regimens for epsilonACA based on the larger V(1), and higher redistribution and clearance variables. We conclude that, because of the developmental differences in pharmacokinetic variables of epsilonACA, when compared with adult patients, a larger initial dose and faster infusion rate as well as an addi-tional dose on CPB are needed to maintain similar concentrations. IMPLICATIONS: Pharmacokinetic modeling of epsilon-aminocaproic acid in children undergoing cardiac surgery suggests that there are developmental differences in pharmacokinetic variables. Based on these data, a dosing modification in children is suggested which may better maintain serum concentrations in children when compared with adults.

Aminocaproic Acid↗