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Biomedical subjects

R E Shaddy

Publications and source records attributed to R E Shaddy.

At least 73 records · Page 4Linked to original sources
PubMed1993

Mid-term results after bidirectional cavopulmonary shunts.

Despite the increasing use of the bidirectional cavopulmonary shunt, little is known about the late results, the duration of palliation, and the frequency with which this procedure allows later successful conversion to a Fontan type of procedure. We reviewed our experience (1984 to 1992) in 38 consecutive children, ages 4 months to 16 years (mean, 4.0 years), who underwent a bidirectional cavopulmonary shunt procedure. All had a single functional ventricle and represented high risks for the performance of a Fontan procedure based on anatomic and hemodynamic criteria. The oxygen saturation in these patients improved from a preoperative value of 75% +/- 7% to 82% +/- 7% (p < 0.05) at late cardiac catheterization by a mean of 24 months after operation. The actuarial survival, including early deaths and that associated with all secondary procedures, was 86% at 1 year and 81% at 6 years. Early deaths occurred in 5.3% (2/38) and late deaths in 11% (4/36). Late follow-up ranged from 5 to 90 months (mean, 37 months). Conversion to a Fontan or fenestrated Fontan procedure was accomplished in 21 early survivors (21/36; 58%) by a mean of 26 months after the bidirectional cavopulmonary shunt procedure, with one operative and no late deaths (1/21; 4.8%). Three additional patients have undergone late reoperation, including 2 requiring cardiac transplantation and 1 undergoing the late creation of an axillary artery-to-vein fistula for the treatment of cyanosis. The midterm survival after a bidirectional cavopulmonary shunt procedure appears to be excellent, and it serves as a good staging procedure for patients who represent high risks for a Fontan procedure.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1993

Comparison of angioplasty and surgery for unoperated coarctation of the aorta.

BACKGROUND: The use of balloon coarctation angioplasty instead of surgery as treatment for unoperated coarctation of the aorta is controversial. The efficacy and complications of the two procedures have not been studied before in a prospective fashion. METHODS AND RESULTS: Thirty-six patients were prospectively randomized to either angioplasty (20 patients) or surgery (16 patients). Immediate results and patient follow-up, including physical examination, angiograms, and magnetic resonance imaging, were compared between groups. Reduction in peak systolic pressure gradient across the coarctation was similar (86%) immediately after both balloon coarctation angioplasty and surgery. On follow-up, aneurysms were seen only in the angioplasty group (20%) and not in the surgery group (0%). No aneurysms have shown progression or required surgery. The incidence of other complications was similar in both groups, although two patients experienced neurological complications after surgery. Although not statistically different, the incidence of restenosis (peak systolic pressure gradient > or = 20 mm Hg) tended to be greater in the angioplasty group (25%) than in the surgery group (6%). Restenosis after angioplasty occurred more frequently in patients with an aortic isthmus/descending aorta diameter ratio < 0.65 and was associated with an immediate catheterization residual peak systolic pressure gradient across the coarctation > or = 12 mm Hg. CONCLUSIONS: Immediate gradient reduction is similar after balloon coarctation angioplasty and surgical treatment of unoperated coarctation of the aorta. The risks of aneurysm formation and possibly restenosis after angioplasty are higher than after surgery, although the risks of other complications are similar. Balloon coarctation angioplasty may provide an effective initial alternative to surgical repair of unoperated coarctation of the aorta in children beyond infancy, particularly in patients with a well-developed isthmus. Further follow-up is necessary to determine the long-term risks of postangioplasty aneurysms.

Angiography↗
PubMed1993

The first pediatric Japanese case to undergo heart transplantation in the Utah Cardiac Transplant Program in the United States.

A seven-year-old girl underwent heart transplantation because of progressive congestive heart failure resulting from familial dilated cardiomyopathy. Her parents were second cousins to each other and her brother had died of dilated cardiomyopathy. Her symptoms of congestive heart failure began four months before the transplantation and became gradually worse. Left ventricular ejection fraction was 10 to 20% echocardiographically, and mitral and tricuspid valve regurgitation were present. Her condition of NYHA IV was not improved by treatment with dobutamine infusion and isosorbide dinitrate. She was transported to the Primary Children's Medical Center in Utah, USA, on July 22, 1991 in critical condition to undergo heart transplantation. Despite treatment with amrinone and additional catecholamines, she became semicomatose due to ischemic liver injury on July 24, 1991. A donor became available on July 25, 1991, and the transplantation was performed. Cardiac ischemic time was 97 min. Although she had transient OKT3 monoclonal antibody-related encephalopathy on her fifth postoperative day, she recovered normally. She had moderate rejection on the 20th postoperative day and mild rejection on the 79th and 149th postoperative days. She has had no significant infectious diseases. The baseline examination performed three months after heart transplantation revealed no abnormal findings on her coronary arteriogram. She returned to Japan and has been attending elementary school. The annual examination of her transplanted heart showed neither stenosis nor occlusion in her coronary angiogram. She has been receiving cyclosporine, azathioprine, and a low dose of prednisone as an immunosuppressive regimen. If she does not exhibit rejection, the use of steroids will be decreased or discontinued.

Cardiomyopathy, Dilated↗
PubMed1992

Cholelithiasis in infants receiving furosemide: a prospective study of the incidence and one-year follow-up.

Cholelithiasis has been reported to occur rarely in infants. To determine the incidence of cholelithiasis in infants receiving furosemide, we prospectively performed ultrasonograms on 86 patients. We studied 42 patients receiving furosemide (subjects) and 44 patients not receiving furosemide (controls). There was a significantly higher incidence of gallstones in subjects (21%) than in controls (2%) (P less than .05). When followed over 1 year, the gallstones did not resolve. There were no significant differences in the dosage of furosemide, gestational age, placement of umbilical venous catheters, or amount of total parenteral nutrition (TPN) between subjects with and without gallstones. However, subjects received more days of TPN (16.7 +/- 15.1) than controls (8.4 +/- 13.2) (P less than .05). These data show that the incidence of cholelithiasis is higher than previously suspected in infants receiving furosemide. Thus, furosemide, either independently or in conjunction with the use of TPN, predisposes infants to the development of cholelithiasis.

Bronchopulmonary Dysplasia↗
PubMed1991

Effects of amrinone on thrombin-induced platelet-derived growth factor-like protein secretion from endothelial cells.

Endothelial cells (EC) secrete platelet-derived growth factor (PDGF)-like protein, which is a potent mitogen to smooth muscle and connective tissue cells. The purpose of this study was to determine if amrinone, a phosphodiesterase inhibitor, could inhibit PDGF-like protein secretion on the basis of its ability to increase cAMP. Human umbilical artery endothelial cells (HUAEC) (n = 7) were preincubated for 4 h with amrinone (10 micrograms/mL) before coincubation with thrombin (10 IU/mL) and amrinone (10 micrograms/mL) for 18 h. The supernatant was then assayed for the presence of both PDGF-like protein by using a competitive 125I-PDGF radioreceptor inhibition assay, and cAMP by using an RIA. Thrombin-induced PDGF-like protein secretion from HUAEC was significantly inhibited by amrinone (7.8 +/- 1.6 fmol/10(6) EC) when compared with thrombin alone (12.1 +/- 2.4 fmol/10(6) EC) (p less than 0.05). Amrinone alone had no effect on baseline PDGF-like protein secretion. Amrinone inhibition of thrombin-induced PDGF-like protein secretion was comparable whether amrinone was added to HUAEC 4 or 0 h before thrombin, and it was dose dependent with a maximal inhibition of 82.7% by amrinone (160 micrograms/mL). In contrast, IL-1 alpha (10 micrograms/mL) and tumor necrosis factor (100 ng/mL) induced less secretion of PDGF-like protein from HUAEC, and this secretion was not inhibited by amrinone. Amrinone (10 micrograms/mL) significantly increased secretion of cAMP from HUAEC from a baseline value of 6.4 +/- 0.4 pmol/10(6) EC to 10.6 +/- 0.1 pmol/10(6) EC (p less than 0.01). We conclude that amrinone inhibits thrombin-induced PDGF-like protein secretion from HUAEC.(ABSTRACT TRUNCATED AT 250 WORDS)

Amrinone↗
PubMed1990

Gradient reduction, aortic valve regurgitation and prolapse after balloon aortic valvuloplasty in 32 consecutive patients with congenital aortic stenosis.

From 1986 to 1988, balloon aortic valvuloplasty was performed in 32 patients with congenital valvular aortic stenosis. The patients ranged in age from 2 days to 28 years (mean +/- SD 8.3 +/- 5.9). One balloon was used in 17 patients and two balloons were used in 15 patients. Immediately after valvuloplasty, peak systolic pressure gradient across the aortic valve decreased significantly from 77 +/- 27 to 23 +/- 16 mm Hg (p less than 0.01), a 70% reduction in gradient. At early follow-up study (4.1 +/- 3.3 months after valvuloplasty), there was a 48 +/- 20.5% reduction in gradient compared with that before valvuloplasty, and at late follow-up evaluation (19.2 +/- 5.6 months), a reduction in gradient of 40 +/- 29% persisted. Echocardiography showed evidence of significantly increased aortic regurgitation in 10 patients (31%) and aortic valve prolapse in 7 patients (22%). There was no correlation between the balloon/anulus ratio and the subsequent development of aortic regurgitation or prolapse. In fact, no patient who showed a significant increase in aortic regurgitation had had a balloon/anulus ratio greater than 100%. It is concluded that balloon aortic valvuloplasty effectively reduces peak systolic pressure gradient across the aortic valve in patients with congenital aortic stenosis. However, subsequent aortic regurgitation and prolapse occur in a significant number of patients, even if appropriate technique and a balloon size no greater than that of the aortic anulus are used.

Adolescent↗
PubMed1990

Right ventricular growth after transventricular pulmonary valvotomy and central aortopulmonary shunt for pulmonary atresia and intact ventricular septum.

We performed transventricular pulmonary valvotomy as initial surgery in 22 consecutive patients with pulmonary atresia and intact ventricular septum who had a patent infundibulum. Nineteen patients also had placement of a central aortopulmonary shunt. All patients survived surgery, and 16 patients have had preoperative and later postoperative catheterizations. The purpose of this study was to determine the response of the right ventricle to transventricular pulmonary valvotomy with regard to relief of right ventricular hypertension and growth of the entire right ventricle, including tricuspid valve, right ventricular volume, and right ventricular outflow tract. Right ventricular systolic pressure decreased from 111.3 +/- 31.7 mm Hg before initial surgery to 65.6 +/- 26.2 mm Hg. Right ventricular end-diastolic volume increased from 59.1 +/- 39.3% of predicted normal before initial surgery to 114.6 +/- 63.2% at late follow-up catheterization. Tricuspid valve anulus circumference also increased in size from 73.2 +/- 21.3% of predicted normal before initial surgery to 90.4 +/- 22.8% at late follow-up catheterization. Only one patient (6%) required a transanular right ventricular outflow tract patch at the time of biventricular repair. Twenty of 22 patients (91%) either have had or are awaiting biventricular repair. We conclude that transventricular pulmonary valvotomy and central aortopulmonary shunt can be performed safely in newborn infants with pulmonary atresia and intact ventricular septum who have a patent infundibulum. Effective valvotomy relieves right ventricular hypertension, allows for excellent right ventricular and tricuspid valve growth, and optimizes potential for biventricular repair.

Aorta↗
PubMed1989

Successful diagnosis and surgical treatment of single ventricle, truncus arteriosus.

The association of single ventricle and truncus arteriosus is rare. We present the successful surgical palliation of a patient who echocardiographically and angiographically has a truncus arteriosus type I and single left ventricle. At operation, the main pulmonary artery was dissected off the truncus arteriosus, and a 4-mm polytetrafluoroethylene graft was placed from the ascending aorta to the left pulmonary artery. The patient is currently 13 months old and growing well.

Echocardiography↗
PubMed1989

Comparative in vitro myocardial inotropic effects and in vivo hemodynamic effects of forskolin and isoproterenol in young lambs.

Previous studies have shown a decreased responsiveness of young lambs to isoproterenol, a beta-adrenergic agonist, when compared to older lambs. To see if this decreased responsiveness of immature lambs is secondary to an abnormality of the beta-adrenergic receptor/adenylate cyclase complex, we compared the effects of isoproterenol to forskolin, a direct activator of the catalytic subunit of adenylate cyclase. In isometrically contracting right ventricular trabeculae from five lambs (5-13 d old), the maximal developed tension with isoproterenol (875 +/- 84 mg, mean +/- SD) and forskolin (704 +/- 189 mg) was similar. However, the median effective dose for isoproterenol (5.3 +/- 3.4 X 10(-7) M) was significantly less than the minimal median effective dose for forskolin (2.5 +/- 1.3 X 10(-6) M) indicating a lesser sensitivity to forskolin. In eight conscious resting lambs (4-13 d old) we measured the hemodynamic response to graded infusions of isoproterenol and forskolin. At maximal dosage, the increase in cardiac output was significantly greater with isoproterenol (+130%) than forskolin (+55%). Heart rate also increased more with isoproterenol than forskolin. These data show that direct stimulation of adenylate cyclase in young lambs does not provide better inotropic or chronotropic responses than beta-adrenergic stimulation with isoproterenol. This suggests that the decreased beta-adrenergic responsiveness in newborn lambs is secondary to abnormalities that exist beyond the level of the beta-adrenergic receptor/adenylate cyclase complex.

Animals↗
PubMed1989

The effects of changes in heart rate and aortic systolic pressure on left ventricular myocardial oxygen consumption in lambs.

To determine whether changes in heart rate and aortic systolic pressure contribute equally to the determination of left ventricular myocardial oxygen consumption, we independently varied heart rate and pressure and compared the resultant oxygen consumption for similar rate-pressure products. In 6 young lambs which underwent atrioventricular node ablation, we varied heart rate by ventricular pacing at 250 beats/min, 300 beats/min, and 120 beats/min while aortic pressure remained stable and varied aortic systolic pressure by infusion of phenylephrine (to 132 +/- 15 mm Hg and 155 +/- 14 mm Hg) and by infusion of sodium nitroprusside (to 79 +/- 6 mm Hg) while heart rate was maintained stable at 200 beats/min. The 3 levels of change in aortic systolic pressure were chosen so that the ratepressure product during the pressure changes matched the rate-pressure product during the heart rate changes. We found that left ventricular myocardial oxygen consumption was the same at all 3 levels of the rate-pressure product whether heart rate was changed and pressure remained stable or pressure was changed and heart rate remained stable. Also, the correlation between oxygen consumption and the rate-pressure product was similar for both heart rate and pressure changes. During nitroprusside infusion at a fixed heart rate, oxygen extraction was significantly lower than during pacing at a heart rate of 120 beats/min when the rate-pressure product was comparable because of the direct vasodilatory effects of nitroprusside. We conclude that heart rate and aortic systolic pressure contribute equally to left ventricular myocardial oxygen consumption at the same rate-pressure product, even though there may be differences in myocardial blood flow and oxygen extraction.

Animals↗
PubMed1988

Short-term hemodynamic effects of captopril in infants with congestive heart failure.

We studied the short-term hemodynamic effects of captopril in ten infants with congestive heart failure secondary to large left-to-right shunts who were refractory to routine medical management with digoxin and diuretics. During cardiac catheterization, captopril (0.5 to 1.0 mg/kg) was administered by nasogastric tube. For the entire group, mean systemic blood flow, pulmonary blood flow, and the pulmonary-to-systemic blood flow ratio did not change significantly after captopril administration. However, in the seven patients in whom baseline systemic vascular resistance was greater than 20 U/m2, captopril decreased the pulmonary-to-systemic blood flow ratio. In contrast, in the three patients in whom baseline systemic vascular resistance was less than 20 U/m2, captopril increased the pulmonary-to-systemic blood flow ratio. We conclude that captopril acutely decreases the pulmonary-to-systemic blood flow ratio in infants with large left-to-right shunts who have elevated systemic vascular resistance. Renal function must be monitored closely when using captopril.

Captopril↗
PubMed1988

Regulation of cardiac output with controlled heart rate in newborn lambs.

To determine the factors regulating cardiac output in newborn lambs and to examine the effects of age after birth, we altered heart rate, afterload, preload, and myocardial contractility in eight younger lambs, 5 to 13 days old, and seven older lambs, 15 to 36 days old. To control heart rate, we ablated the atrioventricular node by injecting formalin into the region of the node, and paced the right ventricle at a baseline heart rate of 200 beats/min. After the lambs recovered from surgery, we performed two protocols. In the first protocol we assessed the effects of changing heart rate by pacing the ventricle at various rates. We also examined the effect of altering afterload and preload at a fixed heart rate: afterload was increased by infusing phenylephrine and decreased by infusing nitroprusside. Preload was increased by infusing blood or 0.9% NaCl solution over 2 min. In the second protocol, we increased myocardial contractility by infusing isoproterenol at a fixed heart rate. Increasing heart rate above baseline levels caused no significant increase in cardiac output in the younger lambs (3.9 +/- 4.0%, mean +/- SD), and only small increases in the older lambs (11.4 +/- 6.7%). Decreasing heart rate, however, resulted in a progressive decrease in cardiac output in both groups of lambs. Decreasing afterload caused no significant increase in cardiac output in the younger lambs (1.4 +/- 14.0%) and only a small increase in the older lambs (11.1 +/- 1.9%).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1986

Pulsed Doppler findings in patients with coarctation of the aorta.

We used combined two-dimensional and pulsed Doppler echocardiography to examine 37 infants and children with coarctation of the aorta and 19 normal subjects. The ages ranged from 1 day to 16 years. We compared the differences between the Doppler flow signal from the ascending aorta and the descending aorta below the coarctation in each patient, as well as the differences between the corresponding flow signals in the aorta of patients with coarctation and normal subjects. Six variables were measured from each Doppler signal: acceleration slope (peak rate of acceleration), acceleration time (time from onset of flow to the peak systolic frequency), antegrade flow time, peak systolic frequency, peak velocity of flow, and deceleration slope (peak rate of deceleration). In patients with coarctation, each of these variables was significantly different in the descending aorta compared with the ascending aorta. There was a decrease in the acceleration slope (14 +/- 13 vs 87 +/- 67 kHz/sec) (mean +/- SD), peak systolic frequency (1.8 +/- 1.0 vs 5.2 +/- 1.9 kHz), peak velocity of flow (0.70 +/- 0.40 vs 1.4 +/- 0.44 m/sec), and deceleration slope (11 +/- 11 vs 27 +/- 12 kHz/sec). There was also a prolongation of the acceleration time (140 +/- 50 vs 88 +/- 22 msec) and antegrade flow time (330 +/- 120 vs 270 +/- 50 msec). In addition, these variables in the descending aorta of patients with coarctation were significantly different from those in the descending aorta of normal subjects.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗