Parathyroid hormone responses to marked hypocalcemia in infants and young children undergoing repair of congenital heart disease.

OBJECTIVES: The integrity of the parathyroid axis was tested in 18 infants and young children undergoing repair of congenital heart disease with cardiopulmonary bypass. BACKGROUND: Infants are believed to have an immature parathyroid hormone response to hypocalcemia. Whereas adults are known to respond appropriately to hypocalcemia during cardiopulmonary bypass, children have not been studied carefully. METHODS: Calcium, magnesium, parathyroid hormone, phosphate and total protein were measured in blood samples withdrawn at defined times before, during and after cardiopulmonary bypass. RESULTS: At the initiation of cardiopulmonary bypass, ionized calcium decreased markedly in 12 infants less than or equal to 24 months old (mean +/- SEM 1.11 +/- 0.04 to 0.29 +/- 0.05 mM) and decreased significantly in 6 young children greater than 24 months old (1.19 +/- 0.02 to 0.42 +/- 0.12 mM). In response to hypocalcemia, parathyroid hormone concentration increased significantly in both the infants (from 42 +/- 8 to 103 +/- 29 and 85 +/- 22 pg/ml) and the young children (from 39 +/- 8 to 44 +/- 20 and 92 +/- 30 pg/ml). Before separation from cardiopulmonary bypass, increased parathyroid hormone concentration restored ionized calcium concentration to 0.75 +/- 0.03 mM in the infants and to 0.92 +/- 0.07 mM in the young children. There was no significant influence of either age or the use of deep hypothermia and circulatory arrest on either calcium or parathyroid hormone responses. Total magnesium and total protein concentrations decreased on initiation of cardiopulmonary bypass and thereafter remained stable. Phosphate concentrations were unchanged during the study. CONCLUSIONS: In infants and young children undergoing cardiac surgery, the parathyroid hormone response to both hypocalcemia and to rising ionized calcium concentrations was at least as great as that of adults. Thus, the calcium-parathyroid-vitamin D axis functions in infants and young children as it does in adults.

Cavernous hemangioma of the superior mediastinum. Report of a case with electron microscopy and computerized tomography.

An unusual case of cavernous hemangioma of the superior mediastinum in a 38-year-old male is presented. Mediastinal hemangiomas occur more often in children and are usually localized in the anterior-superior compartment in all age groups. Slow expansile growth, lack of infiltration of adjacent structures and microscopically mature cellular elements clearly marked the benign nature of the lesion. Vascular mesenchymal tumors in this location must be approached with caution because of the risks of hemorrhage or local infiltration of vital structures. Electron microscopy revealed active endothelial cells, smooth muscle cells, and intercellular matrix components suggestive of smooth muscle cell origin. Computerized tomography delineated the lesion clearly and demonstrated identical densities for the mass and adjacent blood vessels.

Management of symptomatic tetralogy of Fallot in the first year of life.

The surgical management of symptomatic tetralogy of Fallot in infants is debatable. The question of total correction versus palliation and the type of palliative procedure remain controversial. During the past 4 years, 30 infants, aged 1 day to 12 months (mean 5.6 months) with symptomatic tetralogy of Fallot underwent either total correction (21 infants) or palliation by relieving the pulmonary stenosis with a right ventricular outflow tract patch (nine infants). The ratio of diameter of the right pulmonary artery to diameter of the ascending aorta (PA/Ao ratio) was calculated from the anteroposterior cineangiogram of all patients. There were three operative deaths in the total correction group; two of these occurred in infants with PA/Ao ratios less than 0.3. One death occurred in the 19 patients undergoing total correction with PA/Ao ratios greater than 0.3 (mortality rate 5.3%). All nine infants undergoing right ventricular outflow tract patching had PA/Ao ratios less than 0.3, and one operative death occurred in this group. Four patients who had right ventricular outflow tract patching have had repeat cardiac catheterization 2 to 15 months postoperatively. All four have shown symmetrical enlargement of the pulmonary arterial tree and significant increases in their PA/Ao ratios.

Hypoplastic left heart syndrome: palliation without cardiopulmonary bypass.

Our 100% mortality rate with first-stage palliation of hypoplastic left heart syndrome performed with cardiopulmonary bypass led us to a procedure not necessitating bypass. In nine neonates with this congenital heart defect, a woven Dacron graft was placed from the main pulmonary artery to the descending thoracic aorta. The patent ductus arteriosus was ligated and the main pulmonary artery banded distal to the graft and proximal to the bifurcation. Five patients were extubated within 4 days. Only low-dose inotropic support was required in eight of the nine. There were no bleeding problems. Four patients died in the hospital: one of Candida sepsis at 81 days, one of low cardiac output at 2 days, and two of restrictive atrial septal defect at 3 and 5 days. The five living patients were discharged 11 to 80 days postoperatively (mean 38 days). We now perform balloon septostomies preoperatively in all patients and believe that this will improve the survival rate. We believe this simpler approach to the treatment of hypoplastic left heart syndrome may allow survival for a cardiac transplant or a staged Fontan procedure at a later date for more definitive treatment.

Does radial artery pressure accurately reflect aortic pressure?

STUDY OBJECTIVE: Our objective was to determine whether the systolic, diastolic, and mean arterial pressures measured in the radial artery accurately reflect corresponding pressures in the ascending aorta in narcotic-anesthetized patients with known obstructive coronary artery disease, before being subjected to cardiopulmonary bypass (CPB). DESIGN: This was a prospective study. SETTING: The cardiac operating room of a large, tertiary-care university medical center. PARTICIPANTS: Fifty-one patients (45 men and six women; age range, 48 to 77 years) with documented atherosclerotic coronary artery disease were studied. All patients underwent elective coronary artery bypass grafting after the study. INTERVENTIONS: Patients were premedicated with lorazepam and morphine 60 min before administration of Fentanyl-pancuronium anesthesia. The radial artery was cannulated before induction of anesthesia and the aorta approximately 45 min later. Comparisons of radial and aortic pressures were then performed. MEASUREMENTS AND RESULTS: Radial and aortic pressures were recorded through standard, fluid-filled, high-pressure, 91-cm (36-in) long tubing and disposable transducers, meticulously cleared of air bubbles. Additional measurements included cardiac output, central venous pressure, core temperature, blood gas levels, and hematocrit reading. Radial-aortic pressure differences were as follows: systolic arterial pressure (SAP), 12 +/- 1 mm Hg; mean arterial pressure (MAP), -0.8 +/- 0.3 mm Hg; and diastolic arterial pressure (DAP), -1.0 +/- 0.3 mm Hg. All were significant (p < 0.001), but the SAP difference was more than ten times that of either the MAP or the DAP values. The coefficients of determination (r2) indicated that the radial-aortic dependence was 0.44 for the SAP, 0.90 for the DAP, and 0.98 for the MAP relationship. Plotting the respective differences against the arithmetic mean of simultaneously measured pressures indicated that the radial SAP was 4 to 35 mm Hg higher than the aortic in 42 patients (82 percent) and was 10 to 35 mm Hg higher in 26 patients (51 percent); radial-aortic MAP differences clustered within 3 mm Hg in 47 patients (92 percent); radial DAP was +/- 3 mm Hg different from the aortic in 46 patients (90 percent). The largest MAP difference was -6 mm Hg in one patient. The largest DAP difference was +/- 5 mm Hg in three patients. CONCLUSIONS: In this group of patients, who were studied before undergoing CPB, the radial SAP gave a poor estimate of that present in the ascending aorta, since in more than 50 percent of the cases, the radial SAP was 10 to 35 mm Hg higher than that in the aorta. The radial MAP and DAP are reliable, since in 90 percent and 92 percent of the patients, respectively, the pressure differences were within +/- 3 mm Hg of those in the aorta.

Calcium inhibits the cardiac stimulating properties of dobutamine but not of amrinone.

To contrast the effect of increasing blood calcium concentrations on the cardiovascular actions of intravenous beta-adrenergic agonists and phosphodiesterase inhibitors, 46 patients recovering from aortocoronary bypass surgery received either dobutamine or amrinone both in the presence and absence of a calcium infusion. Cardiac output, systemic arterial pressure, pulmonary arterial pressure, central venous pressure, pulmonary artery occlusion pressure, heart rate, and blood ionized calcium concentration were measured before and during infusions of dobutamine (2.5 and 5.0 micrograms/kg/min) and amrinone (0.75 mg/kg bolus + 10 micrograms/kg/min or 2.25 mg/kg bolus + 20 micrograms/kg/min). After the initial dobutamine infusion period, patients were randomly and blindly assigned to receive either a calcium or placebo infusion, and the dobutamine infusions were repeated. Because of the long duration of amrinone's actions, the amrinone maintenance infusion was continued while randomized, blinded infusion of either calcium or placebo was added. Dobutamine (5 micrograms/kg/min) increased cardiac output from 7.1 +/- 0.3 L/min to 9.1 +/- 0.4 L/min, and increased heart rate from 93 +/- 4 beats/min to 107 +/- 4 beats/min. Systemic vascular resistance decreased and stroke volume increased. Dobutamine had no significant effects on other hemodynamic values. Amrinone (2.25 mg/kg bolus + 20 micrograms/kg/min) increased cardiac output from 5.6 +/- 0.4 L/min to 6.9 +/- 0.5 L/min, and increased heart rate from 87 +/- 3 beats/min to 98 +/- 3 beats/min. Amrinone decreased mean arterial pressure, systemic vascular resistance, pulmonary artery occlusion pressure, central venous pressure, and pulmonary artery pressure. Calcium infusion increased arterial pressure (8 to 13 percent) but had no significant effects on any other hemodynamic parameters. Calcium reduced the increase in cardiac output produced by dobutamine by 30 percent, but it did not alter the cardiotonic actions of amrinone. Thus, calcium inhibits the cardiotonic actions of certain beta-adrenergic agonists, most likely by interfering with signal transduction through the beta-adrenergic receptor complex.

Cardiopulmonary bypass and forearm blood flow.

STUDY OBJECTIVE: To assess the effect of cardiopulmonary bypass (CPB) on muscle blood flow (MBF) when measured in the forearm by venous occlusion plethysmography. DESIGN: This was a prospective study. SETTING: Operating room area of a tertiary care university medical center. PARTICIPANTS: Twenty-seven patients (25 men and 2 women), aged 62 +/- 1.5 years, undergoing elective coronary bypass grafting. INTERVENTIONS: Measurements were made during the surgical procedure: before, during cold and warm, and after discontinuation of CPB. MEASUREMENTS AND RESULTS: Changes in forearm blood flow (FBF), derived forearm vascular resistance (FVR), mean arterial pressure (MAP), and cardiac output (CO) were evaluated by repeated measures analysis of variance. The control FBF (measured before CPB) was found to be approximately 50 percent lower than that previously reported for awake volunteers and patients. The FVR was similarly higher. From these low values, the FBF increased significantly (p < 0.001) during normothermic bypass and after CPB. Forearm vascular resistance decreased significantly (p < 0.001) throughout the cold, warm, and postbypass periods. Only during the warm and the postbypass periods did FBF and FVR reach normal values. Mean arterial pressure decreased significantly (p < 0.01) throughout. There was no statistically significant association between any of the variables and FBF or FVR. After correcting for patient and surgical phase variability, only MAP had a statistically significant effect (p = 0.042) on FVR; blood temperature, skin temperature, hematocrit level, PaCO2, serum potassium, and systemic vascular resistance (SVR) had no effect on either FBF or FVR when tested singly or in combination. When correction for multiple comparisons was applied, the lowest probability value became greater than 0.25. There was no correlation between combinations of covariates and FBF or FVR after adjustments for the surgical phase of the study either. CONCLUSION: These findings indicate that the increase in MBF seen during warm and the post-CPB periods is only a recovery toward normal blood flow. The role of this change in the low SVR that usually accompanies CPB is equivocal.

Functional comparison of coronary bypass grafts of the saphenous vein and internal mammary artery.

The magnitude and distribution of myocardial blood flow through a saphenous vein (SV) bypass graft and an internal mammary artery (IMA) graft (diameter greater than or equal to 2 mm) into the same left anterior descending coronary artery (LAD) (diameter congruent to 1.5 mm) were determined at rest, with atrial pacing, and with elevated left ventricular end-diastolic pressure (LVEDP) in 18 dogs. Blood flows through the native LAD, SV, and IMA grafts were similar in the resting heart. With atrial pacing (heart rate = 150% of control), flow in both the SV and IMA grafts increased but the difference was not significant. With elevated LVEDP (20 mm Hg) produced by transfusion, flow in both SV and IMA grafts increased, but, again, these increases were not significantly different. The SV and IMA bypass grafts have similar flow rates at rest and during increased functional demand, provided the grafts are larger than the vessels into which they are placed.

Response of an abdominal aortic thrombotic occlusion to local low-dose streptokinase therapy.

Local low-dose streptokinase infusion (5000 to 6000 IU/hr) as compared to systemic streptokinase infusion (loading dose 250,000 IU/hr, maintenance dose 100,000 IU/hr) successfully relieved a total thrombotic abdominal aortic occlusion. No complications of bleeding or distal embolization occurred during streptokinase therapy, which required only 8 days of hospitalization. When seen at 4 months after streptokinase infusion, the patient was still free of symptoms. When no immediate threat of ischemic limb loss exists, streptokinase may offer a promising therapeutic alternative to surgical intervention for patients who represent a poor operative risk.

Mitral valve operation via an extended transseptal approach.

The extended transseptal approach to the mitral valve has been used for 71 consecutive procedures. Four patients died; none had complications directly attributable to the exposure. Twenty underwent a primary reparative procedure; 30, a primary replacement procedure; and 21, a repeat procedure. Despite division of the sinus node artery, 26 of 32 patients with sinus rhythm preoperatively had sinus rhythm postoperatively; 4 had atrial fibrillation postoperatively. Twenty-seven of 37 patients with atrial fibrillation preoperatively had atrial fibrillation postoperatively; 8 had sinus rhythm postoperatively. Because the exposure provided by this extended transseptal approach is superior to that of standard approaches, we now use it routinely for mitral valve operations.

Endoscopic closure of bronchopleural fistulas using a tissue adhesive.

Bucrylate tissue adhesive has been found to be effective in achieving closure of surgically created bronchopleural fistulas in dogs. Success was obtained with both endoscopic and direct application. Clinical application of this method in one patient was successful [unpublished observations]. We believe that the speed, low risk, and cost-effectiveness of this approach justifies its further use in these difficult situations.

Current treatment of traumatic aortic disruptions.

Eighteen patients with traumatic disruptions of the descending thoracic aorta were treated at the Wake Forest University Medical Center from 1979 through 1986. Their preoperative evaluation and operative management are presented, with emphasis being placed on methods for preventing complications related specifically to aortic cross-clamping. Two patients died, for an operative mortality of 11 per cent. One of the two patients had exsanguinating hemorrhage with profound shock on the way to the operating room; in the second patient, the aorta was occluded just beyond the disruption, and there had been no distal perfusion for several hours before operation. Four patients (22%), three of whom had not had a shunting procedure, had major neurologic complications relating to the spinal cord. Thus, shunting procedures during repair of descending aortic disruption appear to offer some protection from neurologic deficits.

Subxiphoid pericardial window for pericardial effusive disease.

A subxiphoid pericardial window made in 123 patients allowed drainage and diagnosis of pericardial effusions. In 40 patients with malignancy and effusions, median drainage was 450 ml; cytology was positive in 17 or 36 (47%), and pericardial biopsy showed cancer in 13 (43%) of 30 patients. In 11 patients with malignancy, both cytology of effusions and biopsy of the pericardium were negative. In 83 patients with benign effusions, median drainage was 400 ml. Effusions recurred in 14 of the 123 patients (11%); nine patients in the benign group and five in the malignant group. Five of these 14 underwent thoracotomy (3 to 542 days postoperatively); two underwent median sternotomy and one underwent pericardiocentesis. Two intraoperative deaths resulted from cardiac arrest. Mortality at 30 days was 25% (10/40 patients) in the malignant group and 11% (9/83 patients) in the benign group. No deaths resulted from recurrent effusions. The establishment of a subxiphoid pericardial window allows rapid and safe drainage of pericardial effusions with sampling for cytology and pericardial biopsy. It has minimal morbidity and few recurrent effusions.

Empyema of the thorax.

We conclude that following diagnostic thoracentesis, it is appropriate to attempt therapeutic thoracentesis in selected patients with thoracic empyema (especially in the pediatric population). One must be quick, however, to initiate chest tube drainage should this conservative approach fail. The need for prolonged open drainage, such as an Eloesser flap has proved to be indicated seldom for the treatment of thoracic empyemas. Every child was effectively treated with thoracentesis or chest tube drainage alone; none required surgical intervention. Thoracic empyemas can be managed effectively with less aggressive surgical treatment. Rationale and appropriate use of the various drainage methods in as progressive manner are associated with minimal morbidity and mortality.

Prophylactic antibiotics and closed tube thoracostomy.

A prospective randomized study of 85 patients who had sustained trauma to the chest requiring closed tube thoracostomy is reported. They were segregated into two groups, one of which did not receive prophylactic cephapirin sodium. Although the series is somewhat abbreviated, it would appear that the use of prophylactic antibiotics merely for the presence of a chest tube is an unsettled issue and of no definitely proved benefit.

Glutathione peroxidase, superoxide dismutase, and glutathione S-transferase activities in human lung.

Glutathione peroxidase (GSH-Px), superoxide dismutase (SOD), and glutathione S-transferase activities were measured in lung tissue obtained from 7 patients receiving resectional surgery because of localized lung tumors. Human-lung-soluble fractions were also fractionated on Sephadex G-150-S columns, and GSH-Px activity was measured using hydrogen peroxide and cumene hydroperoxide as substrates to investigate the presence of non-selenium-dependent GSH-Px activity. The amount of SOD activity was found to be similar to the amount of activity present in rat lung. Glutathione S-transferase activity was 3 times greater in human lung than that in rat lung. Selenium-dependent GSH-Px activity was much lower in human lung than that in rat lung (less than 30%), and no evidence of non-selenium-dependent glutathione peroxidase activity was found in human lung using gel filtration techniques. We conclude that human lung differs from rat lung in some antioxidant enzymatic defense mechanisms, and that selenium deficiency could result in marked decreases in the ability of human lung to detoxify organic hydroperoxides.

Recent experiences with autotransplantation of the kidney, jejunum, and pancreas.

Ten autotransplants are presented. Renal autografts were performed in the correction of renal artery stenosis, renal artery aneurysm, and intrarenal arteriovenous fistula. All were successful. Jejunal autografts were used to replace the cervical esophagus twice and the entire esophagus once. All grafts were successful, although one patient with advanced cancer died. Pancreatic segmental autografts were used to prevent diabetes following three subtotal pancreatectomies for chronic pancreatitis and one total pancreatectomy for carcinoma. Two patients have functioning grafts, require no insulin, and are free of disease at present. One patient is free of pancreatitis but is diabetic, and one patient died of probable pulmonary embolus. These experiences suggest that organ autografts can be used with greater frequency in clinical surgery and may alter standard therapy for several problems.