Recurrence of aortic insufficiency after aortic root remodeling with valve preservation

Background. Aortic root remodeling (ARR) has recently been proposed for patients with aortic aneurysms and valve insufficiency (AI). To define factors associated with a favorable functional outcome, a review of the mid-term results with ARR was undertaken.

Methods. Between March 1994 and October 1997, 17 consecutive patients (11 men, 6 women), aged 57 ± 11 years (range 35–71), had elective ARR for aortic aneurysm with or without annuloaortic ectasia (13), sinus of Valsalva aneurysm (3), or chronic aortic dissection (1). Moderate or severe AI was present in 11 patients (65%). Preoperative aortic root diameter was 58 ± 5 mm (range 51–70). ARR involved replacement of all three aortic sinuses and coronary button reimplantation, using grafts with a mean diameter of 28 ± 2 mm (range 24–30).

Results. There was one early death (6%) due to multiple organ failure. Survivors were followed for 16 ± 12 months (range 1–44). Actuarial 3-year survival was 94% ± 6%. Discharge echocardiogram showed a decrease in AI in all patients: AI was absent in 11 (69%) and mild in 5 (31%). Recurrence of moderate or severe AI after a mean of 16 ± 9 months (range 9–28) was noted in 6 patients (37%), 3 of whom had no AI at discharge. Five of 6 patients required aortic valve replacement. Comparison of demographic and operative variables showed that severe preoperative AI (67% vs 20%, p = 0.06), annuloaortic ectasia (100% vs 20%, p = 0.002), and cystic medial necrosis (100% vs 20%, p = 0.002) were significantly more prevalent in patients developing severe AI at follow-up. The 10 patients (63%) with absent AI showed durable competence of the valve and relief from symptoms at follow-up.

Conclusions. Despite early restoration of valve competence, AI may recur and progress after ARR at medium-term follow-up in a proportion of patients. The severity of preoperative AI and the nature of aortic root disease may negatively influence the durability of repair. Continued observation of results with ARR appears mandatory to identify the appropriate surgical candidates.     

Preliminary experience with the St. Jude Medical Regent mechanical heart valve in the aortic position: early in vivo hemodynamic results

Background. The St. Jude Medical Regent is a new generation mechanical aortic valve.

Methods. Between March 2000 and July 2001, this valve was implanted in the aortic position in 40 patients (21 men; mean age 59.1 ± 9.0 years). Preoperatively, 24 patients (60%) were in New York Heart Association functional class III or IV. Eighteen patients (45%) underwent associated procedures. Mean valve size was 21.4 ± 2.4 mm. The mean duration of follow-up was 8.5 ± 4.5 months (range, 1 to 16 months).

Results. There were no operative deaths. Early complications included one reoperation for bleeding and one transient low output syndrome. Valve replacement was followed by a significant reduction in mean and peak transaortic gradients over time (p < 0.001) and analysis of variance failed to demonstrate statistical differences between valve size over time (p = not significant). A significant reduction in left ventricular hypertrophy occurred over time (p = 0.01) in all valve sizes (p = not significant between groups): baseline left ventricular mass index was 194 g/cm²; it reduced by 22 g/cm² (p = 0.006) at discharge. Left ventricular mass index decreased from 172 ± 55 g/cm² to 156 ± 44 g/cm² (p = 0.03) from discharge to 2 months. Further reductions were not significant. Relative wall thickness decreased from 0.57 ± 0.13 preoperatively to 0.42 ± 0.06 at discharge (p = 0.001), and again at 2 months (−0.2; p = not significant), and at 1 year (−0.02; p = not significant).

Conclusions. The early experience with the St. Jude Medical Regent valve has been satisfactory.     

Bilateral internal mammary artery grafting: midterm results of pedicled versus skeletonized conduits

Background. To increase the number of anastomoses per patient, bilateral internal mammary arteries (BIMAs) were harvested with a skeletonized approach instead of a pedicled one.

Methods. One thousand one hundred forty-six patients underwent isolated myocardial revascularization using BIMAs, 304 receiving pedicled grafts (group A, October 1991 through May 1994) and 842 receiving skeletonized conduits (group B, June 1994 through June 1998). Group B had a higher incidence of patients with diabetes (223 versus 40, p < 0.001).

Results. The number of BIMA anastomoses per patient was significantly higher in group B (2.4 ± 0.3 versus 2.1 ± 0.4, p < 0.001), as well as the number of sequential grafts (288 versus 42, p < 0.001). Twenty-three patients (2.0%) died in the first 30 days after surgery, 5 in group A (1.6%) and 18 in group B (2.1%) (not significant). Postoperative complications were similar in both groups; the incidence of sternal wound healing problems was higher as a whole and with regard to diabetic patients (4 of 40 [10%] versus 5 of 223 [2.2%], p < 0.05) in group A. Seventy-one patients in group A and 133 (15.8%) in group B underwent a postoperative angiography. Patency rate was similar, both early (100% in group A versus 98.6% in group B, not significant) and late (98.6% in group A versus 98.4% in group B, not significant).

Conclusions. The use of skeletonized BIMA conduits allowed us to increase the number of BIMA anastomoses per patient with a lower rate of sternal wound complications and angiographic results similar to those obtained with pedicled BIMA conduits.     

Reversibility of Cardiac Dysfunction After Valve Replacement in Elderly Patients With Severe Aortic Stenosis

Background. The role of aortic valve replacement for aortic stenosis has not been fully defined in terms of the postoperative reversibility of cardiac dysfunction and pulmonary hypertension in elderly patients.

Methods. Cardiac function, assessed by radioisotope ventriculography and catheterization data, was evaluated before and after operation, and their results were compared between preoperative and postoperative data in each group of younger patients (<69 years, group I, n = 29) and elderly patients (≥70 years, group II, n = 21).

Results. One month postoperatively the peak ejection rate determined by radioisotope ventriculography improved significantly in comparison with the preoperative value in elderly patients (preoperatively, 228 ± 38 versus postoperatively, 319 ± 116% end-diastolic volume per second, p < 0.05), although their preoperative peak ejection rate was severely depressed. The postoperative peak filling rate of the elderly group was not completely reversible to almost normal value, whereas that of the younger group was completely reversible. Early diastolic peak filling rate (one-third peak filling rate) was not reversible in both two groups. Pulmonary hypertension in the elderly patients was reversible to postoperative almost normal pulmonary artery pressure despite the severity of aortic stenosis (systolic pulmonary artery pressure preoperatively, 37 ± 16 mm Hg versus postoperatively, 25 ± 5 mm Hg, p < 0.02; diastolic pulmonary artery pressure preoperatively, 15 ± 6 mm Hg versus postoperatively, 10 ± 4 mm Hg, p < 0.05).

Conclusions. Both cardiac dysfunction, reflected by reduction of peak ejection rate, and pulmonary hypertension in elderly patients with severe aortic stenosis were reversed, reaching almost normal values 1 month after operation.     

Biological and clinical assessment of a new bisphosphonate, (chloro-4 phenyl)thiomethylene bisphosphonate, in the treatment of Paget's disease of bone

Several Biophosphonates have been used as therapeutic agents for Paget's bone disease. (Chloro-4 phenyl)thiomethylene-bisphosphonate (CIPsMBP) has recently been shown to have significant antiosteoclastic activity while an affect of CIPsMBP on mineralization was only observed at high doses. We tested this drug for 6 months in 23 pagetic patients distributed in three groups. Gr 1 (n = 5) receiving 200 mg/day showed a decrease of serum alkaline phosphatase (SAP) to 42 ± 4% (p < 0.01) of initial value (100%) while hydroxyprolinuria/creatinuria ratio (OH/Cr) dropped to 69 ± 8% of baseline. In 4 patients receiving 400 mg/day, SAP improved to 48 ± 9% of initial value (p < 0.01) and OH/Cr to 40 ± 3% (p < 0.01). In the last group (n = 14) receiving 200 mg/day for 3 months, and 400 mg/day thereafter up to the 6th month SAP decreased to 53 ± 4% and OH/Cr to 62 ± 6% of initial value (p < 0.01).

Clinical improvement was significant from the first month of treatment. No resistance (mean decrease of SAP lower than 30%) was recorded and no radiological or clinical evidence of mineralization defect appeared. The clinical and biological tolerance was excellent throughout the study.     

Patient prosthesis mismatch is rare after aortic valve replacement: valve size may be irrelevant

Background. Although small valve size and patient-prosthesis mismatch are both considered to decrease long-term survival, little direct evidence exists to support this hypothesis.

Methods. To assess the prevalence of patient-prosthesis mismatch and the influence of small valve size on survival, we prospectively studied 1,129 consecutive patients undergoing aortic valve replacement between 1990 and 2000. Mean and peak gradients and indexed effective orifice area were measured by transthoracic echocardiography postoperatively (3 months to 10 years). Abnormal postoperative gradients were defined as those patients with mean or peak gradient above the 90th percentile (mean gradient ≥ 21 or peak gradient ≥ 38 mm Hg). Patient-prosthesis mismatch was defined as those patients with indexed effective orifice area below the 10th percentile (< 0.60 cm²/m²).

Results. A multivariable analysis identified internal diameter of the implanted valve as the only independent predictor of abnormal gradients postoperatively. However, there was no significant difference in actuarial survival between normal and abnormal gradient groups (7 years: 91.2% ± 1.5% versus 95.0% ± 2.2%; p = 0.48). Freedom from New York Heart Association class III or IV (7 years: 74.5% ± 3.1% versus 74.6% ± 6.2%; p = 0.66) and left ventricular mass index were not different between normal and abnormal gradient groups. Patients with and without patient-prosthesis mismatch were similar with respect to postoperative left ventricular mass index, 7-year survival (95.1% ± 1.3% versus 94.7% ± 3.0%; p = 0.54), and 7-year freedom from New York Heart Association class III or IV (79.3% ± 6.6% versus 74.5% ± 2.5%; p = 0.40). In patients with patient-prosthesis mismatch and abnormal gradients, the majority had prosthesis dysfunction owing to degeneration.

Conclusions. Severe patient-prosthesis mismatch is rare after aortic valve replacement. Patient-prosthesis mismatch, abnormal gradient, and the size of valve implanted do not influence left ventricular mass index or intermediate-term survival.     

Comparison of outcomes between living donor and cadaveric lung transplantation in children

Background. Long-term survival in lung transplant is limited by bronchiolitis obliterans (BOS). We compared outcomes in pediatric living donor bilateral lobar (LL) vs cadaveric lung transplant (CL).

Methods. Children were studied who had LL or CL with at least 1 year follow-up. Data collected included acute rejection episodes, pulmonary function tests (PFT), BOS, and survival. Mean age was 13.36 ± 3.16 years in LL and 12.00 ± 4.19 years in CL patients (p = 0.37, ns).

Results. There was no difference in rejection (p = 0.41, ns). CL had rejection earlier (2.48 ± 3.84 months) than LL (13.60 ± 10.74 months; p = 0.02). There was no difference in 12 month PFT. But at 24 months, LL had greater forced expiratory volume in 1 second (FEV₁) (p = 0.001) and FEF_25–75% (p = 0.01) than CL. BOS was found in 0/14 LL vs 9/11 (82%) CL after 1 year (p = 0.04). After 2 years, 0/8 LL and 6/7 (86%) CL had BOS (p < 0.05). LL had 85% survival vs 79% for CL at 12 months. At 24 months, LL survival was 77% vs 67% for CL.

Conclusions. Pediatric LL had less BOS and better pulmonary function than CL. As BOS is a determinant of long-term outcome, we believe LL is the preferred lung transplant method for children.     

Brain Damage and Myocardial Dysfunction: Protective Effects of Magnesium in the Newborn Pig

Background. Brain damage is associated with myocardial dysfunction resulting from excessive release of endogenous catecholamines and Ca²⁺ overload. Magnesium ion, a natural Ca²⁺ blocker, has recently been recognized as a myoprotective agent.

Methods. Myocardial function was assessed in 3- to 7-day-old piglets from pressure–volume data (obtained by the conductance catheter/micromanometer technique) before and for 4 hours after ligation of the aortic arch vessels and was correlated with ultrastructural changes. Group a (n = 6) received MgSO₄ immediately after induction of brain damage for 4 hours, whereas group b (n = 6) did not receive MgSO₄ and served as control.

Results. In both groups after induction of brain damage, there was a significant (p < 0.05) increase in end-systolic elastance and preload-recruitable stroke work that persisted for 1 hour. However, after 2 and 4 hours, there was a significant (p < 0.05) reduction in both variables in group b (end-systolic elastance, 74% ± 5% and 59% ± 6%, respectively, and preload-recruitable stroke work, 77% ± 4% and 64% ± 3%, respectively, compared with baseline), and in group a, the values returned to baseline. The chamber stiffness index rose significantly (p < 0.05) in group b 15 minutes after induction of brain damage and remained significantly (p < 0.05) higher for 4 hours versus no significant change in group a. Plasma levels of epinephrine and norepinephrine were similar in the groups before and after brain damage. Electron microscopic study showed severe ultrastructural changes in group b and significantly milder changes in group a.

Conclusions. We conclude that MgSO₄ may protect the neonatal myocardium when administered immediately after brain damage.     

Heparin-Bonded Circuits Decrease Myocardial Ischemic Damage: An Experimental Study

Background. Heparin-bonded cardiopulmonary bypass circuits reduce complement activation, but their effect on myocardial function is unknown. This study was undertaken to determine whether heparin-bonded circuits reduce myocardial damage during acute surgical revascularization.

Methods. In 16 pigs, the second and third diagonal vessels were occluded with snares for 90 minutes followed by 45 minutes of cardioplegic arrest and 180 minutes of reperfusion with the snares released. During the period of coronary occlusion, all animals were placed on percutaneous bypass followed by standard cardiopulmonary bypass during the periods of cardioplegic arrest and reperfusion. In 8 pigs, heparin-bonded circuits were used, whereas 8 other pigs received nonbonded circuits.

Results. Animals treated with heparin-bonded circuits had the best preservation of wall motion scores (3.5 ± 0.3 versus 2.3 ± 0.2; 4 = normal to −1 = dyskinesis; p < 0.05), least tissue acidosis (change in pH = −0.31 ± 0.02 versus −0.64 ± 0.08; p < 0.05), smallest increase in lung H₂O (1.7% ± 0.7% versus 6.1% ± .5%; p < 0.05), and the lowest area of necrosis/area of risk (20.3% ± 2.2% versus 40.4% ± 1.6%; p < 0.05).

Conclusions. We conclude that heparin-bonded circuits significantly decrease myocardial ischemic damage during acute surgical revascularization.     

The efficacy of intraoperative internal intercostal nerve block during video-assisted thoracic surgery on postoperative pain

Background. Video-assisted thoracic surgery (VATS) is widely used for many thoracic surgical procedures. Postoperative pain is less after VATS than after conventional thoracic surgery, but is still significant. The objective of this study was to assess the efficacy of thoracoscopic, internal intercostal nerve block in alleviating immediate postoperative pain.

Methods. Thirty-two patients underwent VATS bilateral sympathectomy for the treatment of hyperhidrosis. The patients were randomly divided into two groups with similar demographic and preoperative physiologic parameters. Group A (n = 16) was submitted to thoracoscopic, internal intercostal nerve blocks performed at T2, T3, and T4 intercostal levels using 3 cc of 0.5% bupivacain in each intercostal space. The injections were performed bilaterally, immediately after the sympathectomy, through the same port. Group B (n = 16) underwent bilateral thoracic sympathectomy without the block. During the immediate postoperative period, heart rate, blood pressure, respiratory rate, pain score, and analgesic requirements were monitored every 30 minutes.

Results. No morbidity was recorded in association with the thoracoscopic, internal intercostal nerve block. The mean heart rates (77 ± 6 vs 89 ± 12 beats per minute, p < 0.001), respiratory rates (15 ± 2 vs 18 ± 3 respirations per minute, p < 0.01), pain score (1.9 ± 0.6 vs 2.7 ± 0.5, p < 0.01), and postoperative analgesic requirements (20 ± 18 vs 50 ± 21 mg pethidine HCL, p < 0.001) were significantly lower in group A. There was no significant difference in blood pressures.

Conclusions. Thoracoscopic, internal intercostal nerve block with bupivacain 0.5% during VATS is safe and effectively reduced the immediate postoperative pain and analgesic requirements.     

Partial left ventriculectomy for idiopathic dilated cardiomyopathy: early results and six-month follow-up

Background. Recent reports show that partial left ventriculectomy improves hemodynamic and functional status in patients with dilated cardiomyopathy. This study sought to determine the effects of partial left ventriculectomy on clinical outcome and left ventricular function during 6-month follow-up.

Methods. Twenty-two patients underwent partial left ventriculectomy. Mitral valve repair was performed whenever possible, otherwise the valve was replaced. Hemodynamic and functional data were obtained at baseline, as well as 2 weeks and 6 months postoperatively.

Results. Overall, 7 of 22 patients died; there were three early and four late deaths. One-year survival was 68% ± 10%. Ejection fraction increased from 23.9% ± 6.8% before the operation to 40.7% ± 12.5% at 2 weeks and to 36.8% ± 7.7% at 6 months (p < 0.001, for both). The cardiac index before the operation, at 2 weeks, and at 6 months was 2.3 ± 0.8, 2.9 ± 0.6, and 3.4 ± 1.0 L/m² per minute, respectively (p = 0.035, and p = 0.009, compared with baseline). The increase in ejection fraction 2 weeks postoperatively was less in patients with left circumflex artery dominance (10.9% ± 3.2% compared with 19.9% ± 10.7%, respectively, p = 0.017). At 6-month follow up, all surviving patients except one improved New York Heart Association functional class when compared with preoperative status (from 3.8 ± 0.4 to 1.4 ± 0.6, p = 0.0002).

Conclusions. Early hemodynamic improvement after partial left ventriculectomy was maintained during midterm follow-up.     

Surgical treatment of acute type A dissection: is rupture a risk factor?

Background. The purpose of this study was to evaluate the significance of aortic rupture on clinical outcome in patients after aortic repair for acute type A dissection.

Methods. One hundred and twenty patients underwent aortic operations with resection of the intimal tear and open distal anastomosis. Median age was 60 years (range 16 to 87); 78 were male. Thirty-six patients had only ascending aortic replacement, 82 had hemiarch repair, and 2 had the entire arch replaced. Retrograde cerebral perfusion was utilized in 66 patients (53%). Rupture defined as free blood in the pericardial space was present in 60 patients (50%). Univariate and multivariate analyses were performed to assess the risk factors for mortality and neurologic dysfunction.

Results. Overall hospital mortality rate was 24.2% ± 4.0% (± 70% confidence level) but did not differ between patients with aortic rupture or without (p = 0.83). The incidence of permanent neurologic dysfunction was 9.4% overall, 10.5% with rupture and 8.3% without rupture (p = 0.75). Multivariate analysis revealed absence of retrograde cerebral perfusion and any postoperative complication as statistically significant indicators for in-hospital mortality (p < 0.05). Overall 1- and 5-year survival was 85.3% and 33.7%; among discharged patients, survival in the nonruptured group was 89% and 37%, versus 81% and 31% in the ruptured group (p = 0.01).

Conclusions. Aortic rupture at the time of surgery does not increase the risk of hospital mortality or permanent neurologic complications in patients with acute type A dissections. However, aortic rupture at the time of surgery does influence long-term survival.     

S100β correlates with neurologic complications after aortic operation using circulatory arrest

Background. Astrocyte protein S100β is a potential serum marker for neurologic injury. The goals of this study were to determine whether elevated serum S100β correlates with neurologic complications in patients requiring hypothermic circulatory arrest (HCA) during thoracic aortic repair, and to determine the impact of retrograde cerebral perfusion (RCP) on S100β release in this setting.

Methods. Thirty-nine consecutive patients underwent thoracic aortic repairs during HCA; RCP was used in 25 patients. Serum S100β was measured preoperatively, after cardiopulmonary bypass, and 24 hours postoperatively.

Results. Neurologic complications occurred in 3 patients (8%). These patients had higher postbypass S100β levels (7.17 ± 1.01 μg/L) than those without neurologic complications (3.63 ± 2.31 μg/L, p = 0.013). Patients with S100β levels of 6.0 μg/L or more had a higher incidence of neurologic complications (3 of 7, 43%) compared with those who had levels less than 6.0 μg/L (0 of 30, p = 0.005). Retrograde cerebral perfusion did not affect S100β release.

Conclusions. Serum S100β levels of 6.0 μg/L or higher after HCA correlates with postoperative neurologic complications. Using serum S100β as a marker for brain injury, RCP does not provide improved cerebral protection over HCA alone.     

Partial versus full sternotomy for aortic valve replacement

Background. Recent trends suggest that smaller incisions reduce postoperative morbidity. This study tests the hypothesis that a partial upper sternotomy improves patient outcome for aortic valve replacement.

Methods. A group of 50 patients who underwent aortic valve surgery through a partial upper sternotomy (group I) were compared to 50 patients who underwent aortic valve replacement through a median sternotomy during the same time period (group II). The mean age (60 ± 2 versus 63 ± 2 years; mean ± SEM) and preoperative ejection fractions (53 ± 2 versus 54 ± 2) were similar. Operations were performed with central cannulation, and antegrade/retrograde blood cardioplegia.

Results. There was one death in each group. No differences were found in aortic occlusion time, mediastinal drainage, transfusion incidence, narcotic requirement, length of stay, or cost. The incidence of pleural and pericardial effusions was increased (18.4% versus 3.9%, p < 0.03), and the need for postoperative inotropic support was higher (38.7% versus 19.6%, p < 0.03) in the partial sternotomy group.

Conclusions. Aortic valve replacement can be performed through a partial sternotomy with results comparable to full sternotomy. The partial sternotomy offers a cosmetic benefit, but does not significantly reduce postoperative pain, length of stay, or cost.     

Spinal cord protection during aortic cross-clamping using retrograde venous perfusion

Background. Paraplegia remains a devastating complication following thoracic aortic operation. We hypothesized that retrograde perfusion of the spinal cord with a hypothermic, adenosine-enhanced solution would provide protection during periods of ischemia due to temporary aortic occlusion.

Methods. In a rabbit model, a 45-minute period of spinal cord ischemia was produced by clamping the abdominal aorta and vena cava just below the left renal vessels and at their bifurcations. Four groups (n = 8/group) were studied: control, warm saline, cold saline, and cold saline with adenosine infusion. In the experimental groups, saline or saline plus adenosine was infused into the isolated cavae throughout the ischemic period. Clamps were removed and the animals to recovered for 24 hours before blinded neurological evaluation.

Results. Tarlov scores (0 = paraplegia, 1 = slight movement, 2 = sits with assistance, 3 = sits alone, 4 = weak hop, 5 = normal hop) were (mean ± standard error of the mean): control, 0.50 ± 0.50; warm saline, 1.63 ± 0.56; cold saline, 3.38 ± 0.26; and cold saline plus adenosine, 4.25 ± 0.16 (analysis of variance for all four groups, p < 0.00001). Post-hoc contrast analysis showed that cold saline plus adenosine was superior to the other three groups (p < 0.0001).

Conclusion. Retrograde venous perfusion of the spinal cord with hypothermic saline and adenosine provides functional protection against surgical ischemia and reperfusion.     

Depressed Function in Remote Myocardium After Myocardial Infarction: Influence of Orotic Acid

Background. We have previously shown that infarction impairs recovery of global function after subsequent cardioplegic arrest and that therapy with orotic acid improves recovery. The aim of this study was to measure the effect of infarction on regional and global left ventricular function and to determine whether orotic acid exerts a beneficial effect exclusive of the effects of cardioplegia.

Methods. Acute myocardial infarction was produced in dogs. They then received either orotic acid or placebo (control) orally (n = 12 per group). Fractional radial shortening and systolic wall thickening were measured by two-dimensional echocardiography before and 1 and 3 days after infarction with and without β-adrenergic blockade, and in 6 dogs up to 9 days after infarction. Global function was measured under anesthesia 4 days after infarction.

Results. In control animals, fractional radial shortening in the infarct decreased from 20.6% ± 5.1% before infarction to 3.0% ± 2.2% at day 1 and to 1.9% ± 1.9% at day 3 (p < 0.01). In the border zone radial shortening declined from 21.9% ± 3.7% to 11.0% ± 2.3% at day 1 and 9.3% ± 2.8% at day 3 (p < 0.05). In the noninfarcted myocardium radial shortening also declined from 27.1% ± 1.9% before infarction to 18.3% ± 2.3% on day 1 (p < 0.05) and to 16.0% ± 2.8% on day 3 after infarction (p < 0.05) with recovery to preinfarct levels by 9 days after infarction. These findings were confirmed by measurements of systolic thickening. Before infarction β-receptor blockade decreased fractional shortening in all regions of the left ventricle, but this effect was absent on day 3 after infarction, implying that the myocardium had become less responsive to β-adrenergic stimulation. Measurements of global function 4 days after infarction showed marked depression of stroke work. There was no effect of orotic acid treatment on regional or global function.

Conclusions. Myocardial infarction causes reversible depression of resting function and β-adrenergic responsiveness in the remote and border zone areas, which is not prevented by metabolic therapy with orotic acid. This finding may explain the adverse response of the infarcted heart to cardioplegic arrest.

(Ann Thorac Surg 1996;62:1765–72)     

Excimer versus carbon dioxide transmyocardial laser revascularization: effects on regional left ventricular function and perfusion

Background. Transmyocardial laser revascularization (TMR) has been established with the carbon dioxide (CO₂) laser. The largely unstudied excimer laser creates channels through chemical bond dissociation instead of thermal ablation, thereby avoiding thermal injury. We sought to compare the effects of CO₂ and excimer TMR in a porcine model of chronic ischemia.

Methods. Pigs underwent ameroid constrictor placement on the circumflex artery to create chronic ischemia. TMR was performed with CO₂ (n = 8) or excimer (n = 8) laser 6 weeks later; controls (n = 7) had ameroid placement only. Regional myocardial blood flow (RMBF), determined by radioactive microspheres, and regional myocardial function, determined by percent segmental shortening (%SS), were assessed 18 weeks after ameroid placement.

Results. Values are mean ± SD. In the ischemic zone, RMBF (mL/min/g) was improved in the CO₂ (0.73 ± 0.19) and excimer (0.78 ± 0.22) groups when compared with controls (0.55% ± 0.12%, p < 0.05). %SS was also improved in the CO₂ (15.2% ± 5.5%) and excimer (15.3% ± 5.1%) groups when compared with controls (8.0% ± 4.2%, p < 0.05).

Conclusions. Excimer and CO₂ TMR significantly improve RMBF and regional function in this porcine model of chronic myocardial ischemia despite fundamentally different tissue interactions.     

Onset of action between bupivacaine 0.5% and bupivacaine 0.5% plus fentanyl 75 mcg

This study tested the hypothesis that the addition of fentanyl 75 mcg to bupivacaine 0.5% at the onset of epidural anesthesia for cesarean section reduces the onset time for T4 sensory blockade. The study was conducted in a randomized, double-blind fashion. The same observer performed sensory testing using pain to pinprick. Fourteen ASA I patients scheduled for elective cesarean section had epidural catheters placed. Group 1 (n = 7) received bupivacaine 0.5%, and group 2 (n = 7) received bupivacaine 0.5% plus fentanyl 75 mcg. Patients 5′0″ to 5′4″ in height received 15 ml, and patients 5′5″ to 5′9″ received 20 ml of bupivacaine. There were no adverse effects on the neonate or clinically important changes in maternal hemodynamics. The maternal age, height, weight, and bupivacaine dose did not differ between groups (p > 0.05). For group 1, the mean times for sensory loss at T7, T6, T5, and T4 were 13.1 ± 3.8 minutes, 15.0 ± 4.0 minutes, 16.9 ± 4.3 minutes, and 19.3 ± 4.9 minutes, respectively; for group 2, the mean times were 8.1 ± 0.9 minutes, 9.9 ± 1.1 minutes, 11.3 ± 1.5 minutes, and 12.7 ± 2.0 minutes, respectively. Two factor analysis of variance between groups 1 and 2 showed a significant difference (p < 0.0001), representing a 35% reduction of mean onset time. The coefficient of variation of the mean onset times for group 1 subjects was 26.6% ± 1.7% and for group 2 subjects 12.7% ± 2.2% (p < 0.001), representing a 50% reduction in between-subject variation. The study demonstrates that the addition of fentanyl to bupivacaine is statistically and clinically significant at reducing the analgesic onset time for cesarean section compared with bupivacaine alone.     

Extensive aortic reconstruction for aortic aneurysms in Marfan syndrome

Background. Marfan syndrome patients frequently develop aneurysms or dissections involving multiple segments of the aorta, and occasionally require staged replacement of the entire aorta. This study reviews the surgical outcome of patients with Marfan syndrome who underwent extensive aortic reconstruction. Extensive reconstruction is defined as reconstruction of more than two segments of the ascending, arch, descending thoracic, or abdominal aorta.

Methods. From March 1973 to December 1997, 101 patients with Marfan syndrome underwent aortic operation. Twenty-six patients (25.7%) had extensive aortic reconstruction. All 26 patients suffered from aortic dissection: 13 patients had Stanford type A and 13 had type B dissection. Twenty-three patients (88.4%) had annuloaortic ectasia and aortic regurgitation. Surgical procedures included composite valve graft replacement (n = 23, 88.4%), aortic arch reconstruction (n = 15, 57.7%), graft replacement of the descending thoracic aorta (n = 6, 23.1%), and graft replacement of the thoracoabdominal aorta (n = 16, 61.5%). Five patients (19.2%) had total thoracoabdominal aortic replacement, and three patients (11.5%) had replacement of the entire aorta. Twenty-one patients (80.8%) required multiple operations.

Results. Follow-up was complete in all patients. The 30-day survival rate was 88.5%. None of the survivors had paraplegia or paraparesis. The overall long-term survival rate was 88.5 ± 6% at 1 year, and 81.7 ± 9% at 9 years.

Conclusions. Aortic surgery prolongs survival in patients with Marfan syndrome, and currently there is a relatively low associated morbidity and mortality even for aggressive surgical treatment.     

Intravenous Phenylephrine Preconditioning of Cardiac Grafts From Non–Heart-Beating Donors

Background. Hypoxia and warm ischemia produce severe injury to cardiac grafts harvested from non-heart-beating donors. To potentially improve recovery of such grafts, we studied the effects of intravenous phenylephrine preconditioning.

Methods. Thirty-seven blood-perfused rabbit hearts were studied. Three groups of non-heart-beating donors underwent intravenous treatment with phenylephrine at 12.5 (n = 8), 25 (n = 7), or 50 μg/kg (n = 7) before initiation of apnea. Non-heart-beating controls (n = 8) received saline vehicle. Hypoxic cardiac arrest occurred after 6 to 12 minutes of apnea, followed by 20 minutes of warm in vivo ischemia. A 45-minute period of ex vivo reperfusion ensued. Nonischemic controls (n = 7) were perfused without antecedent hypoxia or ischemia.

Results. Phenylephrine 25 μg/kg significantly delayed the onset of hypoxic cardiac arrest compared with saline controls (9.6 ± 0.5 versus 7.7 ± 0.4 minutes; p = 0.00001), yet improved recovery of left ventricular developed pressure compared with saline controls (57.1 ± 5.3 versus 41.0 ± 3.4 mm Hg; p = 0.04). Phenylephrine 25 μg/kg also yielded a trend toward less myocardial edema than saline vehicle (p = 0.09).

Conclusions. Functional recovery of nonbeating cardiac grafts is improved by preconditioning. We provide evidence that the myocardium can be preconditioned with phenylephrine against hypoxic cardiac arrest.