Sveneric Svensson

Implantation of a left ventricular assist device, back-to-front, in an adolescent with a failing mustard procedure

easier. The aorta was crossclamped and blood cardioplegic solution was administered antegradely. The optimal positioning of the HeartMate vented electric device was back-tofront, with the inflow directed toward the diaphragmatic wall of the right ventricle and the outflow toward the apex region. Two incisions were made in the diaphragm corresponding to the inflow and outflow tracts. To avoid damage to the liver, from the front of the pump, we made a “pillow” from polytetrafluoroethylene (Preclude pericardial membrane*) stuffed with Dacron felt. When the device was in place, the inflow was on the right side and the outflow on the left side (Fig 2). An expected pulmonary hypertension was prevented with inhaled aerosolized epoprostenol (prostacyclin).4 The early postoperative course in the intensive care unit was uneventful, and after 2 weeks the patient was transferred to the ward. Five weeks after the operation the patient was discharged from the hospital to his home, located 1500 km from our hospital, to await a donor heart. Comment. The need for assist devices in patients with complex congenital heart conditions, as after atrial correction for transposition of the great arteries, could be a surgical technical challenge. Because the right ventricle is the systemic ventricle in transposition, several points must be considered. To place the device on the right side in the abdomen Implantation of mechanical assist devices has saved the lives of patients awaiting heart transplantation.1 The HeartMate left ventricular assist device (Thermo Cardiosystems, Inc, Woburn, Mass) is made to connect the inflow cannula to the apex of the left ventricle.2 We describe a successful case in which the device was placed back-to-front with the inflow cannula inserted into the diaphragmatic wall of the right ventricle and the outflow graft through the left side of the diaphragm and in the left pleura to the ascending aorta (Fig 1). Medical history. A 15-year-old boy who was born with transposition of the great arteries underwent several balloon septostomies at birth because of desaturation. Despite this treatment, the desaturation was persistent. He therefore underwent an operation on an emergency basis at 3 months of age with an atrial switch as described by Mustard (pericardial baffle). At 4 years of age he required a reoperation because of residual atrial shunt and stenosis of the superior vena cava. Ten days after this operation a VVI pacemaker system was implanted because of atrioventricular dissociation. He then had an active life for almost 9 years, after which he gradually noted progressive fatigue and dyspnea. He had a cough, nausea, and cyanosis. Cardiac assessment revealed severe biventricular failure, gross atrioventricular valve regurgitation, and pulmonary hypertension (although reversible), and he was listed for heart transplantation. Despite “optimal” inotropic support, his condition continued to deteriorate with signs of multiorgan failure. Because no donor was available, we decided to implant a HeartMate left ventricular assist system, even though we expected major technical difficulties since the right ventricle, where the inflow cannula had to be placed, was the systemic ventricle. Surgical procedure. A median sternotomy was performed, and the heart, which was heavily adherent, was carefully dissected. Because the patient was thin, we decided to place the pump intraperitoneally.3 The aorta was cannulated. The systemic atrium was cannulated, and a left-sided bypass was instituted. This made the subsequent cannulation of the cavae

Anatomical mismatch of the pulmonary autograft in the aortic root may be the cause of early aortic insufficiency after the Ross procedure

OBJECTIVE Early aortic insufficiency can be a problem after the Ross procedure. Anatomical mismatch and an inexact surgical technique may lead to distortion of the normal pulmonary valve geometry and subsequent incorrect leaflet coaptation and valve insufficiency. In this study, we assessed the efficacy of changing and improving the surgical technique to minimize the early pulmonary autograft valve failure. The modifications and the strategy are discussed. METHODS From January 1995 to February 1999, a total of 77 adults underwent the Ross procedure for aortic valve replacement at Sahlgrenska University Hospital. The operative technique used was full free-standing aortic root replacement with a pulmonary autograft in all cases. In the first 24 cases, the diameter of the pulmonary roots was seldom measured, eye-balling was used to exclude anatomical mismatch due to a dilated aortic root, and only one attempt of correction was made, which failed. In the other 53 cases, the technique was improved by: (1) reducing the aortic anulus diameter in cases with moderate dilatation; (2) excluding cases with severe dilatation of the aortic annulus; (3) adjusting the diameter of the sinotubular junction of the aorta to the diameter of the sinotubular junction of the pulmonary artery; (4). reimplanting the left ostium in the autograft, and (5) changing the proximal anastomosis technique. RESULTS In this study, we had an early aortic incompetence of grade 2 in eight patients among the first 24 patients. In the other 53 patients, postoperative echocardiography at 1 week revealed aortic insufficiency of grade 2 in two patients. CONCLUSIONS Aortic insufficiency after the Ross procedure can be minimized by patient selection, intraoperative correction of anatomical mismatch and improved surgical technique.

Insulin and amino acid infusion after cardiac operations: effects on systemic and renal perfusion.

OBJECTIVE The purpose of this study was to answer two questions: (1) Does a mixed amino acid infusion enhance systemic and renal perfusion in the early postoperative period after heart operations? (2) Does the addition of insulin (glucose-insulin-potassium solution) provide additional effects to those of an amino acid infusion? METHODS Thirty-three male patients undergoing coronary artery bypass grafting (mean age 65.9 +/- 1.2 years) were included in a prospective, controlled, randomized study. Eleven patients (AA group) received infusion of mixed amino acids (11.4 gm), 11 patients (AA + GIK group) received infusion of mixed amino acids (11.4 gm) and insulin solution (225 IU insulin, glucose with glucose clamp technique, and potassium), and 11 patients served as control subjects. RESULTS Amino acid infusion alone had no effect on systemic vascular resistance or cardiac index but increased renal blood flow 51% +/- 11% (from 114 +/- 13 to 172 +/- 24 ml.min-1.m-2 in one kidney, p < 0.05 vs the control group). Insulin solution in addition to amino acid infusion reduced systemic vascular resistance 24% +/- 3% (from 1280 +/- 85 to 960 +/- 57 dyn.sec.cm-5, p < 0.05 vs the control and AA groups) and increased cardiac index 13% +/- 3% (from 2.3 +/- 0.2 to 2.6 +/- 0.2 L.min-1.m-2, p < 0.05 vs the control and AA groups). Insulin had no significant additive effect on renal blood flow. CONCLUSIONS Our data imply that (1) infusion of mixed amino acids enhances renal blood flow after cardiac operations but has no effect on systemic perfusion and (2) the addition of insulin solution improves systemic perfusion. The combined treatment may potentially reduce the risk of renal hypoperfusion injury in the postoperative period after coronary artery bypass grafting.

Glucose and lactate balances in heart and leg after coronary surgery: Influence of insulin infusion

Glucose and lactate balances in leg (representing mainly skeletal muscle) and heart were studied 1 hour after aortocoronary bypass surgery and insulin treatment. Seventeen men were randomized to receive 25 U fast-acting insulin as a bolus injection, followed by continuous infusion of 1 U/kg b.w. for 1 hour, or to serve as controls. In the leg a small glucose uptake was found while the lactate balance was negative. During the study period the lactate release increased further in the control group. In the myocardium no significant extraction of glucose or lactate could be demonstrated. Insulin treatment resulted in a fivefold increment of leg glucose uptake and in significant myocardial glucose uptake. Myocardial lactate balance was also improved by insulin treatment, with fractional extraction increased from 6 to 21%. It is concluded that myocardial carbohydrate metabolism is restricted in the early period after cardiac surgery, and that this seems to result from insulin resistance induced by the surgical trauma.

Renal effects of amino acid infusion in cardiac surgery

OBJECTIVE To evaluate effects of amino acids on renal function and oxygen consumption and the role of individual amino acids on renal blood flow (RBF) changes. DESIGN Prospective, randomized, controlled study. SETTING Operating room in cardiothoracic surgery department, university hospital. PARTICIPANTS Twenty-two male patients submitted to elective first-time coronary artery bypass surgery. INTERVENTIONS A catheter was placed in the left renal vein for thermodilution RBF measurements and blood sampling. In 11 patients, a balanced mixed amino acid infusion was infused (200 mL/hr) for 30 minutes immediately after the operation. MEASUREMENTS AND MAIN RESULTS RBF and glomerular filtration rate increased during amino acid infusion compared with the control group. Renal oxygen consumption increased in the amino acid group and correlated with the increase in RBF (r = 0.70, p<0.001). Amino acid infusion induced two- to fourfold increases in plasma concentrations of individual amino acid concentrations and promoted renal extraction of aspartate, glutamate, glycine, and histidine. No correlation was observed between arterial concentration or uptake of individual amino acids and RBF. CONCLUSIONS The increase in RBF from a mixed amino acid infusion was associated with increased glomerular filtration rate and renal consumption of oxygen. Changes in RBF of a mixed amino acid infusion could not be linked to plasma level or renal uptake of any individual amino acids.

Renal Effects of α-Ketoglutarate Early After Coronary Operations

Abstract Background . α-Ketoglutarate (α-KG) is a Krebs cycle intermediate and the carbon skeleton of glutamate. α-Ketoglutarate has provoked interest in heart surgery because of its proposed critical role in myocardial metabolism. This study investigates the role of α-KG in renal function after cardiac surgical procedures. Methods . Twenty-two patients with normal preoperative renal function were included in a prospective, randomized, and controlled study. Eleven patients received intravenous infusion of 30 g α-KG/hour after the operation. Measurements were performed before operation, immediately after operation, and after 30 minutes of α-KG infusion. Results . Renal blood flow was higher during α-KG infusion, 297% ± 97% (of preoperative value), than in controls, 125% ± 20% ( p p Conclusions . Infusion of α-KG enhances renal blood flow early after coronary surgical procedures in patients with normal renal function. The mechanism is unclear, but could be associated with primarily metabolic effects, and may potentially convey a beneficial effect for renal function.

Glucose-insulin-potassium (GIK) prevents derangement of myocardial metabolism in brain-dead pigs.

Brain death is associated with neuroendocrine changes resulting in reduced myocardial glycogen content. The purpose of this study was to investigate the effects of glucose-insulin-potassium (GIK), on myocardial metabolism in brain-dead pigs. Sixteen brain-dead pigs were given GIK infusion (n = 8), or Ringer solution (n = 8). At end-point (7 h post brain death) arterial concentrations and myocardial arteriovenous (a-v) concentration differences of glucose, lactate and free fatty acids (FFA) were assessed, and myocardial biopsy specimens were taken from the right atrium and left ventricle. Biopsies were also taken from five normal pigs. Myocardial glycogen content in the GIK group was significantly higher compared to the control group, but comparable to the non-brain-dead animals. There was a higher and significant myocardial uptake of glucose and lactate in the GIK group compared to the controls. Plasma levels of FFA were significantly lower in the GIK group, and the myocardial uptake of FFA was 5 times higher in the control group compared to the GIK group. There were no significant differences in hemodynamic variables among the groups. In conclusion, intravenous supply of GIK to brain-dead pigs results in increased myocardial glycogen content and seems to prevent abnormal myocardial metabolism, which may have clinical implications for the myocardial protection of donor hearts.