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Biomedical subjects

T L Gentles

Publications and source records attributed to T L Gentles.

At least 19 recordsLinked to original sources
PubMed2005

Transcatheter closure of a complex postmyocardial infarction ventricular septal defect after surgical patch dehiscence.

Ventricular septal defect (VSD) complicating acute myocardial infarction is a rare but serious event carrying a high mortality. Residual shunting after emergency surgical repair is common, adversely affects prognosis and can necessitate reoperation. We describe the successful transcatheter VSD closure with the Amplatzer occluder in a 75-year old man after earlier emergency surgical repair of a VSD complicating an acute myocardial infarction. The technique and positioning of the device in a tortuous infero-apical VSD are described.

Aged↗
PubMed2001

Left ventricular mechanics during and after acute rheumatic fever: contractile dysfunction is closely related to valve regurgitation.

OBJECTIVES: The purpose of this study was to characterize left ventricular (LV) mechanics during acute rheumatic fever (ARF) and to define factors influencing remodeling after the acute event. BACKGROUND: Acute rheumatic fever is associated with varying degrees of valvulitis and myocarditis, but the impact of these factors on LV mechanics is poorly defined. METHODS: Echocardiograms and clinical data were reviewed in 55 patients aged 11.2 +/- 2.6 years during ARF. Valve regurgitation was absent or mild in 33 (group I) and moderate or severe in 22 (group II). Forty-two children (75%) underwent a further examination after ARF. RESULTS: Group I patients demonstrated a mildly elevated LV size during ARF and had normal indexes at follow-up. Group II patients demonstrated a markedly elevated LV size (end-diastolic dimension z-score 3.6 +/- 1.8, p < 0.01 compared with the normal population) and decreased shortening fraction (z-score -0.8 +/- 1.4, p < 0.05). The stress-velocity index, a z-score describing the velocity of shortening-afterload relationship, was normal in group II patients with mitral regurgitation (-0.2 +/- 1.2, p = NS) but was depressed in those with aortic regurgitation or both (- 1.4 +/- 1.4, p < 0.01). At follow-up the stress-velocity index remained depressed (-1.2 +/- 1.0, p < 0.01) and had deteriorated in those treated nonsurgically compared with those treated surgically (interval change nonsurgical -0.7 +/- 1.2 vs. surgical 1.3 +/- 1.3, p = 0.005). CONCLUSIONS: The evolution of contractile dysfunction during and after ARF is dependent on the degree and type of valve regurgitation and may be influenced by surgical intervention. These findings suggest that mechanical factors are the most important contributors to myocardial damage during and after ARF.

Adolescent↗
PubMed2001

Cardiac output measurements in congenital heart disease: validation of a simple, portable Doppler method.

Noninvasive Doppler cardiac output measurements are clinical standards in adults and children. Presently, these standard Doppler methods generally require relatively expensive and large imaging equipment with complex signal-processing techniques. Thus, universal access to these important measurements has been limited. Simple, portable Doppler methods have been validated previously and applied to infants and children without cardiac disease. Nevertheless, these specific, inexpensive techniques have not been validated in children with complex congenital heart disease. Accordingly, we compared a noninvasive, suprasternal, non-image-guided, pulsed Doppler cardiac output with standard invasive Fick cardiac outputs in 20 patients (age range, 1 month to 15 years) with congenital heart disease. Doppler cardiac output was displayed by multiplying the mean velocity with an operator-selected angiographic or echographic estimate of the aortic diameter. The values from linear regression analysis were r = 0.96; Doppler cardiac output = 0.98 x Fick cardiac output - 0.08 L/min (range, 0.55-3.10 L/min). The 95% confidence limits were less than 35% of the mean of Doppler and Fick cardiac outputs across the range of measurements. We conclude that relatively linear and accurate measurements of cardiac output can be made by this simple, inexpensive, portable method in selected infants and children with various forms of congenital heart disease.

Adolescent↗
PubMed2000

Transposition of the great arteries: operative outcome in the current era.

AIMS: To assess the operative outcome, cardiac and neurodevelopmental sequelae in infants with transposition of the great arteries (TGA) undergoing the arterial switch operation (ASO). METHOD: Cross-sectional review of the 48 consecutive patients operated on in the calendar years 1995 and 1996 was undertaken to obtain recent cardiac, growth and neurodevelopmental parameters, and the mortality results were compared to the entire cohort of infants who underwent the ASO for definitive repair of TGA and double outlet right ventricle at Greenlane hospital between 1984 and 1998. RESULTS: Between January 1995 and December 1996, 48 patients underwent the ASO. 96% were alive, and 88% alive and free from reoperation or significant neurological sequelae at a mean followup interval of sixteen months. Six (13%) had important residual cardiac lesions, of which supra valvular pulmonary stenosis was the most common. Growth parameters at follow-up were normal, as was the neurodevelopmental progress of all but two survivors (96%). CONCLUSION: In the current era, the ASO is a relatively safe procedure with excellent cardiac and neurodevelopmental outcome in the majority of infants.

Cardiac Surgical Procedures↗
PubMed2000

Cognitive development after the Fontan operation.

BACKGROUND: Patients with a single ventricle have multiple risk factors for central nervous system injury, both before and after the Fontan procedure. METHODS AND RESULTS: A geographically selected cohort was invited to undergo standardized testing, including age-appropriate measures of intelligence quotient (IQ) and achievement tests. Historical information was obtained by chart review and patient questionnaires. Of the 222 eligible patients, 133 (59.9%) participated. Median age at testing was 11.1 years (range, 3. 7 to 41.0 years), 6.0 years (range, 1.6 to 19.6 years) after surgery. Mean full-scale IQ was 95.7+/-17.4 (P<0.006 versus normal); 10 patients (7.8%) had full-scale IQ scores <70 (P=0.001). After adjustment for socioeconomic status, lower IQ was associated with the use of circulatory arrest before the Fontan operation (P=0.002), the anatomic diagnoses of hypoplastic left heart syndrome (P<0.001) and "other complex" (P=0.05), and prior placement of a pulmonary artery band (P=0.04). Mean composite achievement score was 91.6+/-15. 4 (P<0.001 versus normal); 14 patients (10.8%) scored <70 (P<0.001). After adjustment for socioeconomic status, independent risk factors for low achievement scores included the diagnoses of hypoplastic left heart syndrome (P=0.004) and "other complex" (P=0.003) or prior use of circulatory arrest (P=0.03), as well as a reoperation with cardiopulmonary bypass within 30 days of the Fontan (P=0.01). CONCLUSIONS: Most individual patients palliated with the Fontan procedure in the 1970s and 1980s have cognitive outcome and academic function within the normal range, but the performance of the cohort is lower than that of the general population.

Adolescent↗
PubMed2000

Misrepresentation of left ventricular contractile function by endocardial indexes: clinical implications after coarctation repair.

BACKGROUND: Endocardial function indexes overestimate myocardial fiber shortening, a geometric effect proportional to wall thickness. We hypothesized that elevated endocardial indexes of left ventricular contractile function after repair of isolated coarctation of the aorta could be related to this effect. METHODS: Chamber dimensions and wall thickness were measured from 59 echocardiograms in 57 patients aged 1.2 to 32 years, 8.5 +/- 5.6 years after coarctation repair, and in 305 normal controls aged 1 to 35 years. Midwall and endocardial shortening indexes and end-systolic fiber stress were calculated. The stress-velocity index (SVI), a load-independent index of contractility, was derived from these variables. All values were expressed as z scores. RESULTS: After coarctation repair, the midwall-derived SVI was elevated, but significantly less so than the endocardial-derived SVI (0.6 +/- 1.6 vs 1.3 +/- 2.6; P =.01). The endocardial-derived SVI correlated with the end-systolic thickness/dimension ratio (P <.0001), but the midwall-derived SVI did not. There was no linear relation between the midwall-derived SVI and the residual blood pressure gradient. The mean midwall-derived SVI was higher compared with the normal population in those with a minor residual blood pressure gradient (</=15 mm Hg) and in those with more significant obstruction (>15 mm Hg), but this achieved statistical significance only in the latter group (0.5 +/- 1.6, P =.08; and 0.8 +/- 1.7, P =.03, respectively). CONCLUSIONS: Endocardial indexes of function and contractility overestimate fiber shortening after coarctation repair. Nevertheless, midwall shortening indexes demonstrate enhanced contractility, particularly in those with residual coarctation.

Adolescent↗
PubMed1997

Fontan operation in five hundred consecutive patients: factors influencing early and late outcome.

OBJECTIVES: The purpose of this study was to review a large, evolving, single-center experience with the Fontan operation and to determine risk factors influencing early and late outcome. METHODS: The first 500 patients undergoing modifications of the Fontan operation at our institution were identified. Perioperative variables were recorded and a cross-sectional review of survivors was undertaken. RESULTS: The incidence of early failure decreased from 27.1% in the first quartile of the experience to 7.5% in the last quartile. In a multivariate model, the following variables were associated with an increased probability of early failure: a mean preoperative pulmonary artery pressure of 19 mm Hg or more (p < 0.001), younger age at operation (p = 0.001), heterotaxy syndrome (p = 0.03), a right-sided tricuspid valve as the only systemic atrioventricular valve (p = 0.001), pulmonary artery distortion (p = 0.04), an atriopulmonary connection originating at the right atrial body or appendage (p = 0.001), the absence of a baffle fenestration (p = 0.002), and longer cardiopulmonary bypass time (p = 0.001). An increased probability of late failure was associated with the presence of a pacemaker before the Fontan operation (p < 0.001). A morphologically left ventricle with normally related great arteries or a single right ventricle (excluding heterotaxy syndrome and hypoplastic left heart syndrome) were associated with a decreased probability of late failure (p = 0.003). CONCLUSIONS: These analyses indicate that early failure has declined over the study period and that this decline is related in part to procedural modifications. A continuing late hazard phase is associated with few patient-related variables and does not appear related to procedural variables.

Child↗
PubMed1997

Functional outcome after the Fontan operation: factors influencing late morbidity.

OBJECTIVES: The purpose of this study was to describe the functional outcome of a large number of patients after modifications of the Fontan operation and to investigate perioperative risk factors that might influence late functional state. METHODS: A comprehensive cross-sectional review of the first 500 patients undergoing a Fontan operation at our institution was undertaken. Those surviving with an intact Fontan circulation were reviewed by questionnaire to assess functional status and medication history. Medical records, chest roentgenograms, echocardiograms, cardiac catheterizations, and laboratory investigations were also reviewed to assess postoperative status. RESULTS: Three hundred sixty-three long-term survivors with an intact Fontan circulation were identified during cross-sectional follow-up. Median age at operation was 5.0 years (range 0.4 to 31 years), and median follow-up was 5.4 years (range 1.7 to 20 years). Most patients (91.1%) were in New York Heart Association class I or II. In a multivariate model, poor (class III or IV) functional state was associated with longer duration of follow-up (p < 0.001), a prior atrial septectomy (p = 0.03), and a prior main pulmonary artery-ascending aorta anastomosis (p = 0.05). CONCLUSIONS: A poor functional outcome is uncommon after the Fontan operation but becomes more frequent with increasing duration of follow-up.

Adolescent↗
PubMed1997

Factors that influence the development of atrial flutter after the Fontan operation.

OBJECTIVES: Atrial flutter is a frequent, potentially fatal complication of the Fontan operation, but risk factors for its development are ill defined. We evaluated clinical features that might predict the development of atrial flutter in patients who had a Fontan operation. METHODS: We evaluated 334 early survivors of a Fontan operation done between April 1973 and July 1991 (mean follow-up, 5.0 +/- 3.8 years). Evaluation included electrocardiography, Holter monitor recordings, and chart review. Modifications of the Fontan operation included an extracardiac conduit (n = 43), an atriopulmonary anastomosis (n = 117), or a total cavopulmonary anastomosis (n = 174). Patient, time, and procedure-related variables were analyzed with respect to the development of atrial flutter. RESULTS: Atrial flutter was identified in 54 (16%) patients at a mean of 5.3 +/- 4.7 years (range 0 to 19.7 years) after Fontan operation. Atrial flutter developed sooner and was more likely to occur in patients who were older at the time of Fontan operation (12.4 +/- 7.6 vs 6.3 +/- 5.2 years; p < 0.001), had a longer follow-up interval (8.7 +/- 3.9 vs 4.4 +/- 3.4 years; p < 0.001), had a prior atrial septectomy or pulmonary artery reconstruction (p < 0.01), and had worse New York Heart Association class symptoms (p < 0.02). The presence of sinus node dysfunction was associated with a higher incidence of atrial flutter (p < 0.001). Although there was a lower prevalence of atrial flutter in those patients with a total cavopulmonary anastomosis, the follow-up for this group was shorter. Anatomic diagnoses, perioperative hemodynamics, and other previous palliative operations were not associated with an increased incidence of atrial flutter. Multivariate analysis identified age at operation, duration of follow-up, extensive atrial baffling, and type of repair as factors associated with the development of atrial flutter after Fontan operation. CONCLUSION: Atrial flutter continues to develop with time after the Fontan operation. Further follow-up is necessary to determine whether a total cavopulmonary anastomosis reduces the incidence of atrial flutter.

Atrial Flutter↗
PubMed1994

Transoesophageal echocardiography detects residual ductal flow during video-assisted thoracoscopic patent ductus arteriosus interruption.

This report describes transoesophageal echocardiographic (TEE) monitoring in a one-year-old boy undergoing patent ductus arteriosus (PDA) interruption. After application of a first vascular clip, echocardiographic monitoring detected incomplete interruption of ductal flow, prompting the surgeon to add a second clip to the ductus. The procedure was performed via a new surgical technique: video-assisted thoracoscopic surgery (VATS). This innovative approach offers many advantages to patient care including reduced postoperative pain and better preservation of pulmonary function. We conclude that the use of TEE monitoring during PDA interruption via the VATS procedure may improve the surgical result, and eliminate reintervention and the complications associated with residual ductal flow.

Ductus Arteriosus, Patent↗
PubMed1994

Pediatric biplane transesophageal echocardiography: preliminary experience.

Recent development of prototype pediatric biplane transducers has extended the use of biplane TEE imaging to the neonate. One such TEE probe with 64 imaging elements in each pallet was used perioperatively in 46 infants and children (weight 2.9 to 32 kg) undergoing surgery for complex congenital heart disease. The success rate for passing the transducer, complications of the procedure, and the number of cases in which the vertical plane provided information that was not available from the horizontal plane were determined. Probe insertion was successful in all patients. Imaging was discontinued in one neonate because of possible airway compression by the probe. Image quality was excellent in the other 45 patients. The vertical plane added information over that obtained from the horizontal plane in 58 (44%) of the 132 anomalies identified. The addition of the vertical plane was especially useful in imaging abnormalities of the ventricular outflow tracts.

Adolescent↗
PubMed1994

Surgical alternatives to the Fontan procedure incorporating a hypoplastic right ventricle.

BACKGROUND: Frequently the definitive operation for patients with a right ventricle (RV) that is too small to support full cardiac output is a modified Fontan operation. However, other surgical options exist that incorporate a small RV in the atriopulmonary pathway when biventricular repair is not feasible because of RV or tricuspid valve hypoplasia. The risks and benefits of these options have not been well defined. METHODS AND RESULTS: Between 1988 and 1993, 8 patients (6 with pulmonary atresia and intact ventricular septum and 2 with tricuspid valve stenosis and RV hypoplasia) underwent a cavopulmonary connection, which allowed right atrial blood to flow either to the pulmonary artery via the RV or directly via the cavopulmonary anastomosis. Age at surgery ranged from 1.5 to 9 years. The proximal right pulmonary artery was ligated in 5 patients, and the atrial septal defect was closed during the same procedure in 7 of the 8 patients. The echocardiographic right ventricular-left ventricular volume ratio ranged from 9% to 25%, and tricuspid valve z-scores ranged from 0 to -4. There were no deaths at a median follow-up of 24 months (range, 7 to 61 months). Mild exertional limitation was evident in only one patient. Postoperative echocardiograms demonstrated pulsatile systolic flow across the RV outflow tract in 5 patients and low-velocity diastolic-systolic flow in a sixth patient with extreme tricuspid valve hypoplasia. At postoperative cardiac catheterization (6 patients) right atrial mean pressures ranged from 7 to 13 mm Hg and mixed venous saturations from 62% to 70%. CONCLUSIONS: Right atrial decompression via a superior vena cava-to-pulmonary artery anastomosis allows incorporation of a small RV into the pulmonary circulation and closure of the atrial septum, with excellent results to date.

Cardiac Catheterization↗
PubMed1993

High pressure balloon angioplasty for branch pulmonary artery stenosis: early experience.

OBJECTIVES: The aim of this study was to evaluate the efficacy and safety of high pressure balloons (17 to 20 atm, Blue Max, Meditech) to dilate branch pulmonary artery stenosis. BACKGROUND: The low success rate (50% to 60%) for angioplasty of branch pulmonary artery stenosis using low pressure balloons is due primarily to the inability to eliminate the balloon waist. Hence, higher inflation pressures may improve results. METHODS: Hemodynamic and angiographic data from 52 patients (0.3 to 34.8 years old) who underwent high pressure balloon dilation of branch pulmonary artery stenosis between October 1990 and February 1992 were reviewed retrospectively, as were data from previous low pressure dilations in these patients. Common diagnoses included tetralogy of Fallot (n = 9), tetralogy of Fallot with pulmonary atresia (n = 23), single ventricle (n = 8) and isolated congenital pulmonary stenosis (n = 7). The 52 patients had 72 vessels dilated. Criteria for success were a > or = 50% increase in vessel diameter or a > 20% decrease in right ventricular to aortic pressure ratio. RESULTS: Of 36 vessels with previously unsuccessful low pressure balloon dilation, 23 (63%) were successfully dilated with high pressure balloons. Of the 36 remaining vessels, 29 (81%) were successfully dilated with high pressure balloons. Factors associated with success were stenosis at a surgical anastomosis and disappearance of the balloon waist with dilation. Aneurysms developed in three vessels. Complications occurred in seven patients (13%); in two patients the distal pulmonary artery was perforated by a stiff guide wire, causing death in one. CONCLUSIONS: Dilation of stenotic peripheral pulmonary arteries with high pressure balloons improves the success rate of angioplasty both in patients who have had unsuccessful dilation with a low pressure balloon and in those without previous attempted dilation.

Adolescent↗
PubMed1993

Right ventricular decompression and left ventricular function in pulmonary atresia with intact ventricular septum. The influence of less extensive coronary anomalies.

BACKGROUND: Right ventricular decompression (RVD) may cause myocardial ischemia in patients with pulmonary atresia with intact ventricular septum and associated coronary artery abnormalities. Although we have previously shown that mortality is very high when two or more coronary arteries are obstructed, the effects of lesser degrees of coronary abnormalities are unknown. We therefore evaluated the effect of RVD on left ventricular (LV) function in those with less extensive coronary artery abnormalities. METHODS AND RESULTS: Preoperative cineangiograms demonstrated fistulas with or without one coronary artery stenosis in 12 of 24 patients aged 2 days to 33 months at the time of RVD. Preoperative and postoperative two-dimensional echocardiograms were analyzed for global and regional LV function. One infant with fistulas involving two coronary arteries and stenosis of the right coronary artery died from severe global LV dysfunction after RVD. Despite this, mean LV end-diastolic volume (66 +/- 17 mL/m2) and mean LV ejection fraction (60 +/- 9%) were similar in patients with and without coronary artery abnormalities before and after RVD. Before RVD, regional LV dysfunction was seen in 8 of 132 (6%) regions in those with coronary artery abnormalities and in 3 of 132 (2%) in those without coronary artery abnormalities. After RVD, there were 16 of 132 (12%) abnormal regions in those with coronary artery abnormalities and 1 of 132 (< 1%) in those without coronary artery abnormalities. In regions with normal wall motion before RVD, the presence of coronary artery abnormalities was related to regional LV dysfunction after RVD (P < .001). CONCLUSIONS: Regional LV dysfunction was rare in patients without coronary artery abnormalities. In those with less extensive coronary artery abnormalities not involving obstruction to multiple coronary arteries, regional LV dysfunction was common before and increased after RVD, but severe global LV dysfunction was unusual.

Child, Preschool↗
PubMed1992

Predictors of long-term survival with Ebstein's anomaly of the tricuspid valve.

In patients with Ebstein's anomaly of the tricuspid valve, predictors of death and indications for surgery are poorly defined. We retrospectively reviewed 48 patients with Ebstein's anomaly, 17 (35%) of whom presented in the first week of life. Duration of follow-up extended to 32 years (greater than 10 years in 35%). Twenty of the 48 patients (42%) died, 6 in the first week of life and 1 at age 5 months. Thirteen of the 41 patients surviving to age 6 months subsequently died, 50% probability of survival being reached at 47 years. Significant (p less than or equal to 0.05) predictors of death in this group were: male sex, cardiothoracic ratio greater than or equal to 0.65, New York Heart Association class III or IV, breathlessness and the absence of Wolff-Parkinson-White syndrome. Eight patients died suddenly. A cardiothoracic ratio greater than or equal to 0.65 was a better predictor of sudden death than functional status. All who developed atrial fibrillation died within 5 years. Other atrial arrhythmias were not helpful in predicting sudden death. In view of these findings, tricuspid valve surgery is recommended before the cardiothoracic ratio reaches 0.65, regardless of the symptomatic state.

Actuarial Analysis↗
PubMed1990

Kawasaki disease in Auckland, 1979-1988.

Records of 34 children diagnosed as having Kawasaki disease in the Auckland region from 1979 to 1988 inclusive were reviewed. Diagnostic and associated features were similar to those reported from North America and Japan. The incidence (average 5.1 per year per 100,000 less than 5 years of age) was similar to that reported in Europe and North America amongst nonorientals and was similar in Polynesians and nonPolynesians. Coronary artery abnormalities were found in five cases (15%), and two cases, both of whom presented before five months of age, died. Those with abnormal coronary arteries had fever for a significantly longer period than those with normal coronary arteries.

Child, Preschool↗