Latissimus dorsi dynamic cardiomyoplasty of the right ventricle. Potential for use as a partial myocardial substitute.

Full-thickness right ventricular latissimus dorsi dynamic cardiomyoplasty with the Medtronic Cardiomyostimulator (Medtronic, Inc., Minneapolis, Minn.) was performed in a chronic canine model. In one group (n = 2) the latissimus dorsi was electrically preconditioned before cardiomyoplasty. In a second group (n = 3) cardiomyoplasty was performed and the muscle was progressively stimulated, with conditioning accomplished while the latissimus dorsi was functioning on the ventricle. The contribution of the stimulated latissimus dorsi to global ventricular function was assessed, and the effects of varying muscle stimulation parameters on latissimus dorsi function and hemodynamics were examined. Right ventricular systolic pressure increased 8%, from 23.2 +/- 0.95 to 25.1 +/- 1.5 mm Hg. The rate of pressure rise increased 37% from 226 +/- 13 to 309 +/- 12 mm Hg/sec. Right ventricular ejection fraction was measured in two dogs and increased 29% with latissimus dorsi stimulation, from 51.5% +/- 13.5% to 66.5% +/- 14.5%. Although the sample size was small, there was no difference observed between the preconditioned and nonpreconditioned groups. Right ventricular systolic pressure, rate of pressure rise, and percent latissimus dorsi fiber shortening increased as voltage and burst frequency of the muscle stimulus increased, whereas increasing the burst duration had little effect in two dogs so studied. Latissimus dorsi dynamic cardiomyoplasty can function as a partial myocardial replacement in a chronic canine model, apparently without preconditioning of the muscle. The degree of cardiac assist obtained with cardiomyoplasty appears to be influenced by the voltage and frequency of the stimulus applied to the muscle. Although it is unclear whether these results can be extrapolated to the left ventricle, this technique may find application in the treatment of ventricular aneurysm or ventricular tumor.

Hemangioma of the right ventricle causing outflow tract obstruction.

A 3 1/2-year-old child had a murmur of pulmonary stenosis. Echocardiography and cardiac catheterization revealed a pulmonary infundibular obstruction. Magnetic resonance imaging of the heart demonstrated a mass in the interventricular septum. The mass was successfully resected and a pathologic diagnosis of capillary hemangioma was made. Only two previous cases of hemangioma causing right ventricular outflow obstruction have been reported; both of these cases involved adults. This case represents the first report of a hemangioma causing right ventricular outflow tract obstruction in a child. An exploratory operation with resection is the treatment of choice.

Effects of dynamic cardiomyoplasty on indices of left ventricular systolic and diastolic function in a canine model of chronic heart failure.

The effects of cardiomyoplasty were evaluated with multiple-gated equilibrium radionuclide angiocardiography and catheterization in a canine model of chronic heart failure. Doxorubicin was administered to 12 dogs at a dose of 1 mg/kg/wk intravenously for 10 weeks. Left ventricular ejection fraction was reduced from a mean of 53.6% +/- 3.4% to 33.5% +/- 2.3% preoperatively. Two dogs died of presumed arrhythmia during this period. Cardiomyoplasty with the left latissimus dorsi muscle was performed on 10 dogs. The muscle was wrapped around both the left and right ventricles. Five dogs died of infection or arrhythmia after the operation. Postoperatively the muscle remained unstimulated for 2 weeks to allow adhesion to the heart. After this period, the latissimus dorsi muscle was conditioned by a progressive stimulation protocol. After the muscle was conditioned, multiple-gated equilibrium radionuclide angiocardiography studies showed that left ventricular global ejection fraction was 18.4% +/- 7.2% at 0 volts (nonstimulation), 26.2% +/- 3.7% at 5-volt stimulation (p less than 0.05), and 31.0% +/- 5.4% at 10-volt stimulation (p less than 0.05). Regional ejection fractions in low lateral, apical, and low septal regions at 5 volts and 10 volts were higher than those at 0 volts (p less than 0.05). Regional wall motion (percent radial shortening) of the low lateral region was higher than that during nonstimulation (p less than 0.05). Peak emptying rate was 2.07 +/- 0.95 end-diastolic counts per second at 0-volt, 3.10 +/- 0.67 at 5-volt, and 3.34 +/- 0.89 at 10-volt stimulation (p less than 0.05). Peak filling rate was 1.81 +/- 0.52 end-diastolic counts per second at 0-volt, 2.67 +/- 1.18 at 5-volt, and 3.11 +/- 0.65 at 10-volt stimulation (p less than 0.05). Cardiac catheterization data showed a nonsignificant increase in left ventricular rate of pressure rise with increasing voltage (1302 +/- 355 mm Hg/sec at 0 volts, 1450 +/- 413 mm Hg/sec at 5 volts, and 1568 +/- 455 mm Hg/sec at 10 volts). Left ventricular systolic pressures were unchanged. End-diastolic pressures decreased (11.2 +/- 1.48 mm Hg at 0 volts, 10.4 +/- 2.30 mm Hg at 5 volts, and 9.6 +/- 1.52 at 10 volts; p less than 0.05). These data show that cardiomyoplasty can improve indices of systolic and diastolic function in a canine model of chronic heart failure.

Pulmonary metastases in pseudomyxoma peritonei syndrome.

BACKGROUND: Pseudomyxoma peritonei (PMP) is a rare disease arising from a mucinous cystadenoma of appendiceal origin. The syndrome has been characterized by progressive growth of mucinous tumors, tense mucinous ascites, and ultimately death. Abdominal and pelvic recurrence after resection of intraperitoneal disease occurs in all patients unless adjunctive measures are taken. Local spread of PMP by direct extension to the pleural or pericardial space is uncommon but has been reported in the literature. Here we report development of pulmonary parenchymal metastases after treatment for PMP. METHODS: The charts of 3 patients were retrospectively reviewed for the presentation and management of metastatic PMP. RESULTS: Three patients underwent resection for pulmonary parenchymal metastases of PMP. All patients recovered uneventfully. The continue to do well after 2 to 8 years of follow-up. CONCLUSIONS: Pulmonary metastasectomy for PMP is safe and effective after treatment of intraperitoneal disease.

Airway management during bilateral sequential lung transplantation for cystic fibrosis.

Bilateral sequential lung transplantation is now an accepted therapy for patients with end-stage cystic fibrosis. In our experience, the use of a standard double-lumen endotracheal tube to establish one-lung ventilation during bilateral lung transplantation has been associated with difficulty in clearing the airway of the thick, tenacious secretions characteristically seen in these patients. Intraoperatively, retained secretions have resulted in inadequate ventilation with subsequent hypercarbia, hypoxia, and the need for cardiopulmonary bypass support. We therefore changed our airway management to a single-lumen endotracheal tube combined with a bronchial blocker to establish one-lung ventilation during bilateral lung transplantation. The lumen of a single-lumen tube accommodates larger suction catheters and an adult bronchoscope, which has a larger suction port. We have used this technique in our last five transplantations, finding easier clearing of airway secretions along with markedly improved ventilation compared with management with a double-lumen tube. We recommend this technique of airway management when performing a bilateral single-lung transplantation for end-stage cystic fibrosis.

Preischemic perfusion of hypertrophied myocardium with perfluorocarbons.

The increased susceptibility of hypertrophied myocardium to ischemic injury is well known. Hypertrophied hearts possess lower preischemic high energy phosphate stores and develop ischemic contracture following a shorter ischemic interval than normal hearts. The purpose of this study was to determine the ability of preischemic, arrested perfusion of the hypertrophied rat heart with oxygenated, glucose-containing perfluorocarbon cardioplegia (FC-43) to restore myocardial ATP stores to normal and prolong the duration of global ischemia prior to contracture initiation. Hearts from normal (NL) rats and hypertrophied hearts from spontaneously hypertensive rats (SHR) were subjected to 2 or 15 min of preischemic, arrested perfusion with FC-43 utilizing a modified Langendorff preparation. ATP was determined via HPLC and time to initiation of ischemic contracture was measured. Two minutes of FC-43 perfusion restored ATP in the SHR group to normal levels (P = NS compared to normal controls) and prolonged the time to initiation of ischemic contracture by 107%. Perfluorocarbons, with their unique oxygen-carrying properties, may be an ideal vehicle for intervention designed to enhance the tolerance of hypertrophied hearts to ischemia.

Reduction of myocardial infarct size by poloxamer 188 and mannitol in a canine model.

Poloxamer 188 has been reported to inhibit thrombosis, decrease whole blood viscosity, and improve perfusion of damaged tissue. Mannitol has free radical scavenging capabilities that might contribute to myocardial salvage after ischemia. Because these agents appear to work in different ways, we studied their cardioprotective properties when they were used separately and in combination. After 75 minutes of left anterior descending coronary artery (LAD) occlusion, dogs received poloxamer 188 (48 mg/kg), mannitol (0.5 gm/kg), or both intravenously during an additional 15 minutes of LAD occlusion and for 45 minutes of reperfusion, whereas control dogs received an equal volume of saline solution. After surgery the animals were maintained for 24 hours and then killed. Areas of myocardial infarction (MI) and risk of infarction (R) were calculated by means of planimetric analysis of slices of myocardium stained with 1.5% triphenyltetrazolium and 0.5% Evans blue dye. The ratio of MI/R (mean +/- standard error of the mean) were: control, 25.6 +/- 1.8% (n = 10); poloxamer 188, 12.7 +/- 2.0% (n = 10); mannitol, 10.6 +/- 2.5% (n = 11); and poloxamer 188 plus mannitol, 8.0 +/- 4.1% (n = 10). Measurement of microvascular blood flow indicated a similar 86% to 91% reduction of blood flow to the area at risk in all treatment groups. Consequently both poloxamer 188 and mannitol appear to increase salvage of ischemic myocardium and a combination of the two may be more effective than either agent alone.