Post-cardiotomy mechanical circulatory support using a conventional bypass circuit in children.

OBJECTIVE: Mechanical circulatory support (MCS) is increasingly used after cardiotomy in children when conventional medical treatment fails. Poor overall survival and long-term outcome have been reported. We report our experience of post-cardiotomy MCS using a conventional bypass circuit. METHODS: Over a 4 year and 6 month period 10 patients, with a median age of 16 days (range 5 days to 16 years) required MCS. Eight patients required support for failure to wean from cardiopulmonary bypass during primary correction. Two patients required support for cardiac arrest or poor cardiac output in the postoperative period. RESULTS: The median duration of support was 43 h (range 26-146 h). Seven hospital survivors were alive and well at median follow-up of 18 months (range 4-36 months). One patient could not be weaned off support. Two more patients died after successful weaning from support. Complications in nine patients who could be weaned off support included renal failure (n=6), cerebrovascular events (n=3) and mediastinitis (n=2). CONCLUSIONS: Overall long-term survival (70%) and quality of recovery is usually good even though initial mortality and complication rates may be high. We think that post cardiotomy mechanical circulatory bypass using a conventional bypass circuit can offer a favourable outcome to selected patients.

Norwood-type operation with adjustable systemic-pulmonary shunt using hemostatic clip.

The postoperative course of a patient with hypoplastic left heart syndrome after a first-stage Norwood operation is governed to a large extent by the balance between the systemic and pulmonary circulations. Here we describe a simple and convenient technique for establishing an optimally sized systemic-pulmonary shunt by the application of a hemostatic clip. The method has been used in 6 patients.

Failure of ductus arteriosus closure and remodeling in neonatal mice deficient in cyclooxygenase-1 and cyclooxygenase-2.

The transition to pulmonary respiration following birth requires rapid alterations in the structure of the mammalian cardiovascular system. One dramatic change that occurs is the closure and remodeling of the ductus arteriosus (DA), an arterial connection in the fetus that directs blood flow away from the pulmonary circulation. A role for prostaglandins in regulating the closure of this vessel has been supported by pharmacological and genetic studies. The production of prostaglandins is dependent on two cyclooxygenases (COX-1 and COX-2), which are encoded by separate genes. We report here that the absence of either or both COX isoforms in mice does not result in premature closure of the DA in utero. However, 35% of COX-2(-/-) mice die with a patent DA within 48 h of birth. In contrast, the absence of only the COX-1 isoform does not affect closure of the DA. The mortality (35%) and patent DA incidence due to absence of COX-2 is, however, significantly increased (79%) when one copy of the gene encoding COX-1 is also inactivated. Furthermore, 100% of the mice deficient in both isoforms die with a patent DA within 12 h of birth, indicating that in COX-2-deficient mice, the contribution of COX-1 to DA closure is gene dosage-dependent. Together, these data establish roles for COX-1, and especially for COX-2, in the transition of the cardiopulmonary circulation at birth.

Tetralogy of Fallot: what operation, at which age.

BACKGROUND: The optimal management of tetralogy of Fallot is still under debate, particularly with respect to surgical approach and the age of operation. In recent times a transatrial-transpulmonary approach and primary repair in younger patients is favoured. The purpose of the present study was to analyze the result of our current surgical management by assessing the perioperative and intermediate term follow up in order to define the optimal strategy and timing of operation for our institution. METHODS: One hundred and thirty two patients with tetralogy of Fallot who underwent definitive repair between May 1993 and December 1998 were analyzed by reviewing their medical records and follow-up. Median age was 15. 5 (2.3-68.6) months and median weight was 8.8 (5-16) kg. Ten (7.57%) patients were under 6 months, 38 (28.78%) were between 6 and 12 months, 36 (27.27%) were between 12 and 18 months, 23 (17.42%) were between 18 and 24 months and 25 (18.93%) were more than 24 months age. During the study period there was a move to earlier surgery and differing methods of repair depending on the anatomy observed. Follow up was conducted by the referring cardiologist. Median follow up was 35.48 (8.07-74.93) months. RESULTS: Forty-two (31.8%) patients required a palliative procedure before total correction due to unfavourable anatomy. Subpulmonary infundibular obstruction with a fibrous component increased significantly with age (P<0.05). Operations were entirely transatrial in 14 (10.6%), transatrial and transpulmonary in 69 (52.2%), transatrial and transventricularly in 42 (31.8%) and a homograft conduit was used in seven (5.3%) patients. Younger patients had narrower pulmonary valves and required a transannular patch more frequently. All patients were in sinus rhythm, 28 (21.1%) showing right bundle branch block. Median hospital stay was 8 (5-54) days. No patient required reintervention during follow up and there was no early or late mortality. CONCLUSION: Correction of tetralogy of Fallot at younger age does not increase morbidity or mortality and has potential advantages. A surgical technique adapted to the anatomy of the right ventricular outflow tract, achieves the best results.

Perifused precision-cut liver slice system for the study of hormone-regulated hepatic glucose metabolism.

A nonrecirculatory perfusion system for precision-cut rat liver slices has been developed and utilized for investigating hormone-regulated hepatic glucose metabolism. In this system, slices are cultured in a highly controlled environment and exhibit excellent retention of viability as judged by their maintenance of intracellular potassium and glycogen contents. Using this system, the complex physiological phenomenon of hormone-regulated glycogenolysis was investigated at both extra- and intracellular sites. Specifically, the sensitive responses of intracellular cyclic AMP (cAMP) production, activation of cyclic AMP-dependent protein kinase, and production of glucose upon glucagon stimulation have been measured. The maximal responses observed for these parameters were either equal to or greater than those previously reported for either isolated hepatocytes or perfused livers, demonstrating the sensitivity of this technique. Upon dose-response examination of glucagon challenge, it was observed that high doses of glucagon (greater than 16 nM) stimulate glucose production by activating the cAMP-second messenger cascade. In contrast, low doses (less than 4 nM) stimulate this process without production of intracellular cAMP or activation of cAMP-dependent protein kinase, suggesting the operation of cAMP-independent messenger. Since this system permits measurements of parameters common to many cellular processes, this methodology is suitable for addressing both pharmacological and toxicological questions.