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Biomedical subjects

T P Graham

Publications and source records attributed to T P Graham.

At least 55 records · Page 3Linked to original sources
PubMed1987

Hemodynamic effects of hydralazine in infants with idiopathic dilated cardiomyopathy and congestive heart failure.

We evaluated the acute hemodynamic responses to hydralazine during cardiac catheterization in 13 infants with idiopathic dilated cardiomyopathy. Ages ranged from 2 to 13 months (6.7 +/- 4.0 months, mean +/- SD). Each infant had congestive heart failure and angiographic evidence of markedly depressed left ventricular ejection fraction (0.24 +/- 0.11; normal = 0.58-0.78) with left ventricular dilation (left ventricular end-diastolic volume = 349 +/- 125% of normal). Hydralazine (0.5 to 1.0 mg/kg administered intravenously) acutely decreased systemic arteriolar resistance from 21.1 +/- 3.3 to 12.0 +/- 2.7 U/m2 (p less than 0.001). This 41 +/- 14% decrease in systemic resistance was accompanied by a 45 +/- 16% increase in cardiac index (3.24 +/- 0.53 to 4.71 +/- 0.99 L/min/m2; p less than 0.001). Mean arterial blood pressure declined from 70 +/- 8 to 60 +/- 11 mm Hg (p less than 0.001). Hydralazine also increased heart rate (122 +/- 19 to 138 +/- 18 bpm; p less than 0.001), but this increase did not account entirely for the change in cardiac index as evidenced by a rise in stroke volume index (26.9 +/- 4.9 to 34.5 +/- 7.5 ml/beat/m2; p less than 0.001). Pulmonary arteriolar resistance and pulmonary capillary wedge pressure fell slightly in response to hydralazine. Subsequently, oral hydralazine was included in the treatment regimen of 10 infants followed for 3 to 38 months (mean = 15 months). Of these, eight demonstrated sustained clinical improvement. We conclude that hydralazine may be a beneficial adjunct to the management of congestive heart failure in young infants with a dilated cardiomyopathy.

Angiography↗
PubMed1987

Myocardial adenosine triphosphate content as a measure of metabolic and functional myocardial protection in children undergoing cardiac operation.

In an effort to quantitate the metabolic and functional response to global myocardial ischemia as a prelude to specific interventions to improve myocardial protection in children, the following data were collected. Twenty children (age, 1.16 +/- 0.3 years) underwent repair of congenital intracardiac malformations using aortic cross-clamping and cold potassium cardioplegia (ischemic time, 56.1 +/- 4.5 minutes). Metabolic protection was assessed by measuring the myocardial adenosine triphosphate (ATP) content by microbioluminescence. Before and after ischemia 10-mg myocardial samples were obtained from the left ventricular apex using a Tru-cut biopsy needle. In 15 patients, postoperative ventricular function was measured by radionuclide ventriculography at 72 to 96 hours following operation. Five of 6 patients with a postischemic ATP level less than 40% of control (26.3 +/- 2.8) had a left ventricular ejection fraction (EF) lower than 55% (50.3 +/- 2.3). Seven of 9 patients with an ATP level greater than 40% of the preischemic level (98.0 +/- 14.4) had a normal EF (61.8 +/- 2.9; p less than 0.04). Two other patients with postischemic ATP levels lower than 40% of control died of low cardiac output and had no postoperative ventricular function studies. Thus, of 7 patients with postischemic ATP levels lower than 40% of preischemic levels, 2 died and 5 had depressed left ventricular function. These data support the concept that low postischemic ATP levels correlate with death or poor postoperative ventricular function, and indicate that this variable will be useful to assess future improvements in myocardial protection during pediatric cardiac operations.

Adenosine Triphosphate↗
PubMed1987

Surgical treatment of pediatric cardiac arrhythmia.

The combination of improved diagnostic techniques, new and potent antiarrhythmia agents, and progress in antiarrhythmia surgical procedures has resulted in successful management of complex cardiac arrhythmia in children. The kinds of arrhythmia that can be considered for possible surgical intervention share several features. Each produces symptoms and usually is hemodynamically compromising. Each requires extensive preoperative and intraoperative electrophysiologic evaluation to establish the mechanism, response to drugs, and suitability for surgery. Although reports of surgical arrhythmia treatment have been limited in children, with increasing success the indications for such treatment may become less stringent. Our recommendations are shown in the Table. In general, patients intolerant of or unresponsive to medical treatment for symptomatic arrhythmia (tachycardia or bradycardia), should be considered candidates for surgical antiarrhythmia procedures. These patients should be referred for testing to cardiac centers staffed by pediatric cardiac electrophysiologists and surgeons experienced in arrhythmia diagnosis and ablation. Careful evaluation can identify those patients in whom surgical approaches are most appropriate. At present, surgical operations for selected, serious pediatric cardiac arrhythmias offer definitive and possibly curative treatment, and may be preferable to inadequate, poorly tolerated, or long-term medical therapy.

Adolescent↗
PubMed1987

Surgical intervention in neonates with critical pulmonary stenosis.

The surgical experience with 18 consecutive neonates with critical pulmonary stenosis (PS) and intact ventricular septum was reviewed. All patients had cardiac catheterization with calculation of right ventricular volume. Group A patients (N = 8) had a small right ventricular end-diastolic volume (RVEDV less than 72% of predicted). Group B patients (N = 10) had a normal or enlarged RVEDV. All patients had a closed pulmonary valvotomy. Five Group A patients required a systemic-pulmonary shunt or prostaglandin (PGE1) after operation; one patient died. Nine Group B patients did well after valvotomy; one moribund patient died after valvotomy and shunt. Six of 16 survivors required reoperation: valvectomy in four patients and shunt takedown in two patients. Four of the six patients who had reoperation also had a transannular patch. There was one unrelated late death. All long-term survivors are asymptomatic. Recatheterization in four patients with a small right ventricle (RV) documented significant RV growth. In conclusion, most neonates with critical PS can be managed with closed valvotomy. Patients with a small RV may require PGE1 or a shunt after operation for persistent hypoxemia. Some patients with a small RV will have significant RV growth after valvotomy.

Heart Defects, Congenital↗
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↗
PubMed1987

Left ventricular wall stress and contractile function in transposition of the great arteries after the Rastelli operation.

Left ventricular wall stress and contractile function were determined by echocardiographic methods in 11 patients studied 0.7 to 13.8 years (mean +/- standard error of the mean = 5.6 +/- 1.2 years) after undergoing the Rastelli operation for transposition of the great arteries associated with ventricular septal defect and left ventricular outflow tract obstruction. Age at operation ranged from 4.6 to 11.3 years (mean +/- standard error of the mean = 7.4 +/- 0.7 years). Data were compared with data of 24 normal subjects of similar age and heart rate. Left ventricular end-diastolic dimension and end-diastolic volume were significantly higher than normal, averaging 134% +/- 8% of normal dimension (p less than 0.004) and 106 +/- 13 ml/m2 versus a normal volume of 60 +/- 3 ml/m2) (p less than 0.007). In addition left ventricular wall mass was 215 +/- 40 gm/m2 versus a normal value of 72 + 6 gm/m2 (p less than 0.004). Both meridional and circumferential end-systolic and peak systolic stress values were not significantly different between normal subjects and Rastelli patients. Estimates of ventricular pump function including shortening fraction, rate-corrected velocity of circumferential fiber shortening, and ejection fraction were all depressed when compared with normal values. Velocity of fiber shortening, evaluated as a function of end-systolic stress, demonstrated abnormal contractile function in eight of 11 (73%) patients. These data indicate that left ventricular function is usually abnormal and residual left ventricular dilation and wall hypertrophy remain despite successful use of the Rastelli operation for repair in patients with transposition of the great arteries, ventricular septal defect, and left ventricular outflow tract obstruction.

Adolescent↗
PubMed1986

Ventricular pump performance in patients with obstructed right ventricular-pulmonary artery conduits.

Postoperative data were obtained from 18 patients with partially obstructed right ventricular (RV) to pulmonary artery (PA) conduits, who were studied 1 to 9 years following a Rastelli operation. Age at operation was 1 to 8 months in seven patients (group I: infant group) and 2 to 9 years in the remaining 11 patients (group II: childhood group). The diagnosis was pulmonary atresia in eight patients, truncus arteriosus in seven, and transposition of the great arteries with ventricular septal defect and pulmonary stenosis in three. Porcine-valved conduits were inserted in 17 patients and an aortic homograft in one. All but seven patients were free of symptoms at the time of postoperative study. Neither peak RV pressures nor RV to PA gradients were different between groups. RV ejection fraction (EF) was decreased in group II (0.43 +/- 0.11) but was normal (0.60 +/- 0.10) in group I. In addition, there was a significant inverse relationship between RVEF and age at repair (r = 0.714; p less than 0.005). RV end-diastolic volume (EDV) was normal or increased in all patients and did not differ between the two groups. Left ventricular (LV) ejection fraction was also decreased in the older group (0.56 +/- 0.10 vs 0.68 +/- 0.08; p less than 0.05), and there was a decrease in RVEF and/or LVEF from pre- to postoperative studies in one of six group I patients compared with four of five group II patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Angiocardiography↗
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

Membranous supravalvular mitral stenosis: a treatable form of congenital heart disease.

The clinical data, echocardiographic findings, operative anatomy and postoperative follow-up were assessed in 14 patients who had surgery for membranous supravalvular mitral stenosis between 1978 and 1985. The patients ranged in age from 6 weeks to 13 years at the time of operation, and 8 of the 14 had associated mitral valve abnormalities. Other associated lesions included ventricular septal defect (n = 7), coarctation of the aorta (n = 5), left superior vena cava (n = 6), subaortic stenosis (n = 3) and atrial septal defect (n = 1). Twelve of the 14 patients had successful removal of the supravalvular membrane, which was usually adherent to the valve, and 2 patients with associated mitral valve abnormalities underwent mitral valve replacement. There were no operative deaths. Review of preoperative two-dimensional echocardiograms, which were available in 11 patients, revealed two types of membranous supravalvular mitral stenosis in 10 patients. In four of these patients, the membrane was only evident after repeated stop action viewing from a single subcostal or parasternal location. The membrane was never seen in one patient. Eleven patients had follow-up in excess of 1 year, and there was one late death. Eight of the remaining 10 patients are asymptomatic, and 7 have no clinical evidence of residual mitral obstruction. Failure to recognize membranous supravalvular mitral stenosis can result in undue delay of cardiac surgery with resultant cardiopulmonary deterioration. Patients with evidence of left ventricular inflow obstruction should have extensive echocardiographic evaluation in an effort to detect membranous supravalvular mitral stenosis, which may be amenable to surgical repair.

Adolescent↗
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↗
PubMed1986

Effects of endotoxin on coronary vascular resistance in the isolated blood-perfused rabbit heart.

Rabbit hearts were excised and perfused with blood pumped through a cannula placed in the aortic root. A fluid-filled balloon-tipped catheter was positioned in the left ventricle for the measurement of left ventricular pressure and dP/dt. Total coronary vascular resistance (CVR) was calculated by dividing the coronary perfusion pressure by the rate of coronary blood flow. Following stabilization, coronary blood flow was held at a constant rate. Compared to control hearts, endotoxin (E. coli) added directly to the blood perfusate (6 mg/80 ml of circulating blood) had no effect on CVR or left ventricular dP/dt. In contrast, changing the perfusate to blood obtained from rabbits previously given endotoxin (LD100; 6 mg/kg IV) resulted in significantly higher CVR, without depression of left ventricular dP/dt. This increase in CVR was observed not only when the endotoxemic donor rabbits were hypotensive at the time the blood was obtained (4-6 hours following endotoxin administration), but also when the endotoxemic donors remained normotensive (blood withdrawn 30 minutes following endotoxin administration). A pathologic increase in CVR might contribute to the myocardial ischemia and contractile dysfunction observed in endotoxin shock.

Animals↗
PubMed1985

Beneficial effects of perfluorochemical artificial blood on cardiac function following coronary occlusion.

This study compares the effects of perfluorochemical artificial blood versus whole blood on the systolic and diastolic function of regionally ischemic myocardial preparations. Regional ischemia was produced by ligation of the circumflex coronary artery in isolated, blood-perfused rabbit hearts. Three minutes after occlusion, half the hearts were switched from the blood perfusate to perfluorochemical artificial blood; the other half continued to be perfused with blood. Isovolumic left ventricular (LV) developed pressure, dP/dt and resting pressure were monitored before, and for 2 hours after coronary occlusion. After 90 minutes of regional ischemia, perfluorochemical-treated hearts exhibited significantly greater developed pressure than those perfused with blood (78 +/- 6% versus 61 +/- 5% of preligation values; P less than 0.05). At the end of the experiment, LV dP/dt was 21% greater in the perfluorochemical-perfused group than in the blood-perfused group (74 +/- 8% versus 53 +/- 10%; P less than 0.01). Perfluorochemical perfusion also preserved diastolic function by preventing the 58% increase in left ventricular chamber stiffness (i.e., resting pressure; P less than 0.01) associated with circumflex ligation. Thus, in the present model of regional ischemia, perfluorochemical artificial blood is significantly better than blood at maintaining both systolic and diastolic myocardial function after a major coronary artery has been occluded.

Animals↗
PubMed1985

Operative repair of coarctation of the aorta in infancy: results with and without ventricular septal defect.

Coarctation of the aorta (CA) presenting in infancy is a life-threatening condition, especially if associated with intracardiac left-to-right shunts. Between 1971 and 1980, 51 infants with symptomatic CA have been diagnosed and treated. Ventricular septal defect (VSD) was present in 18 patients and patent ductus arteriosus in 24. End-to-end repair was performed in 20 patients, 17 (85%) of whom were long-term survivors. Subclavian flap angioplasty repair was used in 28 patients, of whom 25 (89%) were long-term survivors. During long-term follow-up 6 patients (35%) who underwent end-to-end repair had recurrent CA, whereas only 3 patients (12%) who underwent subclavian flap angioplasty had recurrent CA (p less than 0.05). The mortality rate in patients with associated VSD was higher (4 of 18, 22%). Pulmonary trunk banding with subsequent VSD repair was associated with a better survival (13 of 14 patients, 90%) than when banding was not performed (2 of 5 patients) (p less than 0.05). These results suggest subclavian flap angioplasty is the preferred treatment for symptomatic CA occurring in infancy. Concomitant pulmonary trunk banding in patients with VSD can be performed with the expectation of a lower mortality at subsequent VSD repair.

Aortic Coarctation↗
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↗