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Biomedical subjects

T P Graham

Publications and source records attributed to T P Graham.

At least 19 recordsLinked to original sources
PubMed1992

Pre-operative assessment of ventricular function in patients considered for Fontan procedure.

In 1978 Choussat and Fontan established ten criteria, which should be fulfilled to achieve a successful outcome in Fontan operation. Recent data suggest that while some of these ten criteria need not be necessarrily be fulfilled, new criteria should be added. These include 1. good diastolic function, 2. normal or only slightly increased ventricular mass, and 3. absence of systemic outflow obstruction. In addition the morphology of the single ventricle may be important as long-term results in patients with single ventricle of right ventricular morphology may be worse than results in patients with single ventricle of left ventricular morphology. Ventricular size and pump function can be assessed by cardiac catherization, echocardiography or magnetic resonance imaging. Estimation of ejection fraction under stress by nuclear angiography may be indicated. Diastolic function can be examined using Doppler echocardiography or nuclear angiography. Myocardial mass may be assessed by echocardiography or magnetic resonance imaging. Normal reference values for different parameters of systolic and diastolic function are listed in the enclosed tables. Patients scheduled for a Fontan operation should have an ejection fraction less than 50%. Patients with borderline ejection fraction should be examined by echocardiography to determine the end-systolic wall stress, a parameter of ventricular contraction, which is independent of pre- and afterload. As afterload may decrease after a Fontan operation some patients with reduced ejection fraction but normal end-systolic wall stress may still be suitable candidates for Fontan operation.(ABSTRACT TRUNCATED AT 250 WORDS)

Heart Defects, Congenital↗
PubMed1991

Unique variant of partial anomalous pulmonary venous connection with intact atrial septum.

Partial anomalous pulmonary venous connections (PAPVCs) are rare in association with an intact atrial septum. However, the diagnosis should be considered in patients with otherwise unexplained findings of left-to-right shunt and right heart enlargement. An unusual variant is presented, which we considered unsuitable for operative repair, based on findings at catheterization. Developmental, hemodynamic, and surgical considerations are discussed.

Angiography↗
PubMed1991

Complete repair of atrioventricular septal defect.

We report our experience with 103 consecutive children who underwent repair of complete atrioventricular septal defect between 1971 and 1990. Ninety-one patients were less than 18 months old (mean age, 6.2 months; mean weight, 5.8 kg) and were repaired using deep hypothermia and circulatory arrest. There were 15 perioperative deaths. Twelve patients were older (mean age, 40.2 months; mean weight, 18.9 kg) and were repaired using moderate hypothermia and cardiopulmonary bypass. There were two perioperative deaths. Repairs were performed with the single-patch technique. Four younger patients required repeat repair to control residual mitral regurgitation. Two of the older children required late reoperation to replace one or both atrioventricular valves. Three younger children underwent pulmonary artery banding initially; 1 died after complete repair. Three older children underwent initial pulmonary artery banding; 2 died at definitive repair, and the survivor required pulmonary artery reconstruction, which was repeated subsequently. Since 1977 our policy has been to perform primary definitive repair whenever possible. Two patients died late from unrelated causes. At the most recent follow-up the majority of patients had no or minimal symptoms. We continue to advocate primary definitive repair whenever possible using the single-patch technique in symptomatic patients with complete atrioventricular septal defect.

Cardiac Catheterization↗
PubMed1991

Echocardiographic estimation of critical left ventricular size in infants with isolated aortic valve stenosis.

With the current trend to performing surgical valvotomy for infantile aortic stenosis without cardiac catheterization, there is a need to develop echocardiographic criteria for adequacy of left ventricular size. The echocardiograms and catheterization data of all 25 infants less than 3 months of age undergoing aortic valvotomy for isolated aortic valve stenosis from September 1980 through July 1990 were reviewed. Significant differences (p less than 0.05) between the survivors and nonsurvivors were noted for age at operation (30 +/- 28 vs. 3 +/- 1.5 days), mitral valve diameter (10.1 +/- 1.7 vs. 7.7 +/- 1.5 mm), left ventricular end-diastolic dimension (18.4 +/- 6.4 vs. 11.4 +/- 3 mm), left atrial dimensions (15.3 +/- 3.8 vs. 10 +/- 2.4 mm), left ventricular cross-sectional area on the parasternal long-axis echocardiogram (4 +/- 1.9 vs. 2 +/- 1.9 cm2) and angiographically determined left ventricular end-diastolic volume (43 +/- 23 vs. 11 +/- 5 ml/m2). There was no difference with respect to patient weight, body surface area, aortic root dimension or left ventricular ejection fraction. Left ventricular cross-sectional area less than 2 cm2 as measured on the parasternal long-axis echocardiogram was found in 5 of 7 nonsurvivors and 0 of 12 survivors, making this a risk factor for perioperative death (p less than 0.05). Left ventricular end-diastolic dimension less than 13 mm was found in 5 of 6 nonsurvivors and 2 of 17 survivors, making this another risk factor for early mortality (p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Aortic Valve↗
PubMed1990

Normal values for noninvasive estimation of left ventricular contractile state and afterload in children.

The outcome and suitability for therapeutic interventions in children with congenital heart disease depend frequently on left ventricular function. Congenital heart disease is characterized by changes in loading conditions, making it difficult to assess ventricular contractility using conventional load-dependent indexes. Two-dimensional and M-mode echocardiography and arterial blood pressure were used to study left ventricular morphometrics and contractility in 44 normal children, aged 2 to 12 years. Left ventricular end-systolic and end-diastolic length, diameter, wall thickness, volume and mass all showed linear increases with body surface area (p less than 0.001 in all). Shortening and ejection fractions, velocity of circumferential fiber shortening, morphometric ratios and endocardial meridional and circumferential stress (mean 46 and 115 g/cm2, respectively) all remained constant. A load-independent measure of the normal resting left ventricular contractile state was determined by relating the rate-corrected velocity of circumferential fiber shortening to end-systolic endocardial meridional and circumferential stress; there was an inverse linear correlation (r = -0.641 and -0.557 respectively, p less than 0.001). These data provide a quantitative basis for assessment of myocardial hypertrophy, afterload and contractile state in childhood.

Blood Pressure↗
PubMed1990

Reappraisal of localized resection for subvalvar aortic stenosis.

Between June 1972 and August 1989, we operated on 45 patients with fixed subaortic stenosis. Discrete membranous stenosis was present in 28 patients and tunnel stenosis, in 13. Four patients had subvalvar stenosis complicating double-outlet right ventricle. There were 33 male and 12 female patients. Mean age at operation was 7.1 +/- 4.3 years (range, 6 months to 21 years). Local resection of the fibrous membrane was performed in 26 patients. Local resection was combined with myectomy in 18 patients. Aortoventriculoplasty (modified Konno procedure) was required at operation in 3 patients. There were three perioperative deaths at initial operation and two deaths at the time of reoperation. Follow-up ranges from 1 month to 17 years (average follow-up, 47.0 months). Reoperation for recurrent obstruction has been required in 12 patients (27%), and 3 patients have required a second reoperation. Mild to moderate aortic regurgitation was present in 17 patients. Subaortic stenosis is a spectrum of anatomical derangements ranging from a discrete fibrous membrane to a long, tortuous fibrous tunnel with aortic annulus hypoplasia. Successful removal of a discrete fibrous membrane can be followed later by recurrent stenosis necessitating myectomy or aortoventriculoplasty. Correction of subvalvar aortic stenosis can be followed by recurrent stenosis necessitating reoperation as long as 17 years after the initial procedure.

Cardiomyopathy, Hypertrophic↗
PubMed1990

An outbreak of acute rheumatic fever in Tennessee.

From January, 1987, until July, 1988, a significant increase in newly diagnosed cases of acute rheumatic fever was noted at our hospital. In sharp contrast to the 3 cases seen in 1986, 14 cases were diagnosed in 1987 (a significant increase from 1985 to 1986, P = 0.001). In the first 6 months of 1988 an additional 12 new cases were diagnosed (a further significant increase from 1987, P = 0.02). No further cases were diagnosed between July, 1988, and September, 1989. The major clinical manifestations were carditis in 73%, polyarthritis in 58% and chorea in 31%. In 15 of 26 patients an antecedent illness which included pharyngitis was noted; the remainder of patients were asymptomatic. Group A beta-hemolytic streptococci were isolated from 13 of 19 children cultured. Isolates from two patients with acute rheumatic fever were submitted for M typing: one isolate was mucoid M18/T18; the other isolate was a mucoid nontypable strain. The demographic characteristics of the 26 patients agree with classic descriptions in that patients were more likely to be urban, to come from large families and to have low incomes; racial breakdown of the group mirrored the Tennessee pediatric population. These characteristics stand in contrast to reports of recent outbreaks which describe suburban high income patients. These data suggest that practitioners should be again aware of acute rheumatic fever and that aggressive identification and treatment of streptococcal pharyngitis should continue to be a relevant public health concern.

Acute Disease↗
PubMed1990

Impact of Fontan operation on left ventricular size and contractility in tricuspid atresia.

Left ventricular dimensions and contractility were determined by echocardiography in 33 patients with tricuspid atresia in 1985 and again in 1988. Eight patients remained palliated throughout the 3-year period; neither the left ventricular end-diastolic diameter (153 +/- 15% of normal vs. 157 +/- 19%, p = NS) nor a load-independent index of contractility (rate-corrected velocity of shortening [VCFc]/end-systolic meridional stress [ESSM]) changed. Eleven patients underwent a Fontan operation during the study and were reevaluated at least 6 months after surgery; left ventricular dimension decreased (130 +/- 15% vs. 114 +/- 19%, p less than 0.001), and the contractility index VCFc/ESSM improved (p less than 0.05). Fourteen patients had undergone a Fontan operation 0.9-9.5 years (mean, 4.2 years) before initial examination in 1985. Over the 3-year period, left ventricular dimensions did not change (121 +/- 17% vs. 118 +/- 11%, p = NS), but the contractility index showed significant improvement (p less than 0.01). Eight additional patients were studied just before and after a Fontan operation to examine the early effects of surgery. Left ventricular dimensions decreased from 130 +/- 14% to 100 +/- 13% by 10 days p less than 0.001) with no further change at 2 months. An inappropriate degree of ventricular hypertrophy was observed in only the early postoperative period. Successful Fontan repair results in rapid reduction of left ventricular size, followed by regression of hypertrophy to a normal mass-to-volume ratio. Operating at more favorable dimensions and loading conditions results in an early increase in left ventricular contractility, which further improves in the medium term follow-up.

Echocardiography↗
PubMed1989

Absence of left ventricular volume loading in infants with coarctation of the aorta and a large ventricular septal defect.

Clinical characteristics and angiographic ventricular volume data were obtained in 25 infants aged 1 to 66 days who presented with coarctation of the aorta, ventricular septal defect and congestive heart failure to determine if left ventricular volume loading was present and if there were hemodynamic or volumetric variables that were predictive of operative mortality in this group. Pulmonary to systemic flow ratio averaged 2.8 +/- 0.8 and right ventricular/left ventricular peak pressure ratio was 0.96 +/- 0.12. Left ventricular end-diastolic volume averaged 116 +/- 49% of normal and was less than the investigators' lower limit of normal in 5 (20%) of 25 patients. In contrast, right ventricular end-diastolic volume, measured in eight patients, averaged 173 +/- 47% of normal and was greater than the investigators' upper limit of normal in seven (88%) of eight. Left ventricular ejection fraction averaged 0.47 +/- 0.17 and was below normal (less than 0.55) in 14 (58%) of 24 patients. Preoperative volume and ejection fraction data did not differ in infants with coarctation plus ventricular septal defect and a similar group of 19 infants with isolated coarctation. Abnormal left ventricular operative volume distensibility was inferred by normal or decreased left ventricular end-diastolic volume and increased left ventricular end-diastolic pressure (greater than 12 mm Hg) in 12 (55%) of 24 patients. Early plus late mortality was related to left ventricular size: 3 of 5 patients with a small left ventricular end-diastolic volume died, compared with only 4 of 20 with a normal or increased volume (p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Abnormalities, Multiple↗
PubMed1989

Clinical assessment of ventricular function after surgical treatment of congenital heart defects.

The assessment of ventricular function has contributed to the current surgical evaluation and surgical treatment of congenital heart defects, but many issues remain unresolved. The challenge of assessing ventricular function after surgical repair of congenital heart defects includes not only the general problem of distinguishing adverse loading conditions from myocardial failure but also more unique problems of right heart function and developmental differences in ventricular function. The possibility and significance of diastolic dysfunction are essentially unexplored and contingent upon our better understanding of the determinants of diastolic indices. Many of the technologies and methods are currently available and there is the beginning of a move toward better designed clinical trials and analysis of results. The assessment of ventricular function will become increasingly important as surgical techniques are improved and we are left with the more difficult choices between competing approaches.

Cardiac Output↗
PubMed1987

Effects of postnatal maturation on postrest potentiation in isolated rabbit atria.

Ultrastructural changes in cardiac sarcoplasmic reticulum (SR) have been reported during postnatal development of the mammalian heart, but the functional significance of these observations has not been well characterized. Calcium release from SR in intact myocardial preparations was determined by the contractile characteristics of postrest contractions. Isometric tension and the maximum rate of tension development of the first contraction following intervals of electromechanical quiescence (rest) were related to steady-state tension and maximum rate of tension development during contraction at constant frequency (1.0 Hz) in isolated left atrial strips from newborn (1-7 days), immature (14-21 days), and adult (more than 6 months) rabbits. The first postrest contraction was increased as a function of the rest interval rate of tension development, defined as postrest potentiation, in all three age groups and reached a maximum value at rest intervals of more than 20 s. Tension developed by the first contraction following a 60-s rest interval was potentiated less in newborn and immature atria than in adult atria at an extracellular calcium concentration ([Ca]e) of 2.5 mM, an age-related difference most marked in the immature. Ryanodine (5.0 X 10(-9) M), a putative blocker of calcium release from cardiac SR, abolished postrest potentiation providing evidence that calcium release from SR is the predominant determinant of the postrest contraction. Postrest tension in atria from the immature rabbit heart was significantly increased both in absolute terms and relative to steady-state tension following stabilization under conditions which increase intracellular [Ca] [( Ca]i), i.e. increasing [Ca]e, increasing tonicity, or decreasing extracellular sodium concentration ([Na]e).(ABSTRACT TRUNCATED AT 250 WORDS)

Aging↗
PubMed1986

Repair of interrupted aortic arch and associated malformations in infancy: indications for complete or partial repair.

There is uncertainty regarding the best method of repair of interrupted aortic arch. The question is whether to perform primary definitive repair of this anomaly plus the associated defects versus arch repair only and palliation of the intracardiac defects, usually by pulmonary artery banding. Since 1976, 16 infants with interrupted aortic arch have been treated surgically. They were seen at 5.2 +/- 3 days of age and weighed 3.2 +/- 0.7 kg. The interruption occurred between the left carotid and left subclavian arteries (type B) in 9 and between the left subclavian artery and the descending aorta in 7 (type A). Isolated ventricular septal defect (VSD) was the only associated anomaly in 7 and aortopulmonary window, in 4. Two patients had truncus arteriosus type 1. Three had transposition of the great arteries: 1 with VSD and 2 with single ventricle. Prior to 1980, our policy was to palliate all patients. Between 1976 and 1980, 4 infants underwent left thoracotomy with arch repair plus pulmonary artery banding (3, VSD; 7, transposition of the great vessels and single ventricle) with only 1 (25%) survivor. Because of this high mortality, 8 patients with interrupted aortic arch and VSD or aortopulmonary window, seen since 1980, received complete repair with median sternotomy, end-to-end arch anastomosis, and closure of the VSD or aortopulmonary window utilizing profound hypothermia and circulatory arrest. All 8 survived.(ABSTRACT TRUNCATED AT 250 WORDS)

Aorta, Thoracic↗
PubMed1986

Left ventricular wall stress and contractile function in childhood: normal values and comparison of Fontan repair versus palliation only in patients with tricuspid atresia.

Left ventricular wall stress and contractile function were determined by echocardiographic methods in 23 patients with tricuspid atresia after palliation only (group 1), in 19 patients after Fontan repair (group 2), and in 24 age-matched normal subjects. End-diastolic dimension was increased above normal in both groups with tricuspid atresia (group 1 [mean +/- SEM] 141 +/- 4%, group 2 129 +/- 5% of normal; both p less than .001) but were not different from each other. Left ventricular end-diastolic volume and wall mass also were increased above normal in both groups (group 1, 126 +/- 9 ml/m2 and 194 +/- 19 g/m2, respectively, p less than .001 and p less than .004; group 2, 80 +/- 7 ml/m2 and 128 +/- 10 g/m2, p less than .02 and p less than .001), and group 2 patients showed significantly lower values than group 1 patients (p less than .001 and p less than .004). Meridional end-systolic stress was increased above normal in both groups with tricuspid atresia but was not different between groups (normal, 43 +/- 3 g/cm2; group 1, 56 +/- 54 g/cm2, p less than .02; group 2, 59 +/- 7 g/cm2, p less than .001). Contractile function estimated by rate-corrected circumferential fiber shortening velocity was abnormal in nine of 23 (39%) group 1 patients and in five of 19 (26%) group 2 patients (percentages not different from each other by nonparametric testing). Contractile function was depressed in one of 11 group 1 patients under 5 years old and in eight of 12 over 5.3 years old.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1985

Tetralogy of Fallot: selective surgical management can minimize operative mortality.

Although tetralogy of Fallot can be completely corrected at any age, it appears that preliminary shunting may be of benefit in infancy. To better define the optimum age for shunting, the following patient data were reviewed. One hundred five patients with tetralogy of Fallot were treated between December, 1975, and July, 1984. Eight of 100 patients undergoing intracardiac repair died. Operative mortality was 14.3% (4 of 28 patients) when intracardiac repair was done before the patient was a year old, but only 5.6% (4 of 72 patients) after that age. Seven (13%) of 54 patients requiring transannular patch reconstruction of the right ventricular outflow tract died, whereas only 1 (2.2%) of 46 having repair without this type of reconstruction died (p less than 0.05). Twenty-one patients were initially palliated with systemic-pulmonary artery shunts, with 1 noncardiac death related to associated congenital neurological anomalies (4.8%). There was no statistically significant difference in mortality for primary versus secondary intracardiac repair. Left ventricular end-diastolic volume determination in 26 patients less than 2 years old demonstrated that 14 patients had small left ventricles and that 3 of them less than 1 year of age died at corrective operation. The remaining 12 had a left ventricle of normal size, and 1 of them died at operation. Palliative shunts can be performed safely in the very young child with no increased mortality at subsequent intracardiac repair. Diffuse hypoplasia of the right ventricular outflow tract and pulmonary arteries requiring transannular patch reconstruction, and age less than 1 year both alter operative mortality, their combined impact being additive.

Adolescent↗