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Biomedical subjects

W S Pierce

Publications and source records attributed to W S Pierce.

At least 127 records · Page 7Linked to original sources
PubMed1979

Congenital aortic valve anomaly. Aortic regurgitation with left coronary artery isolation.

A case is reported of aortic regurgitation resulting from a congenitally abnormal aortic valve. The left coronary cusp of the valve was small and adhered to the aortic wall, so that there was insufficient valve tissue to maintain diastolic valve competence. In addition, this rudimentary cusp completely occluded the left coronary ostium. The patient was treated successfully by valve replacement.

Adolescent↗
PubMed1979

Acute hypertension: its significance in traumatic aortic rupture.

Traumatic aortic rupture is a common occurrence associated with 16 percent of deaths from automobile accidents. Through a review of current literature and two recent cases from The Milton S. Hershey Medical Center, we have attempted to elucidate a common physical finding, acute hypertension associated with blunt chest trauma, and prove its significance as a diagnostic clue to traumatic rupture of the aorta. New laboratory findings of an aortic sympathetic reflex stimulated by stretching the aortic wall in the area of the isthmus provides a physiological explanation for the cause of hypertension after aortic trauma.

Accidents, Traffic↗
PubMed1979

A two and one half year clinical experience with a mechanical left ventricular assist pump in the treatment of profound postoperative heart failure.

A sac-type paracorporeal left ventricular assist pump was implanted in 9 patients suffering from profound left ventricular failure following open heart surgery. Two patients had good recovery of left ventricular function and were weaned from assist. One survived 14 months postoperatively. Primary causes of death among the remaining patients were (1) primary right ventricular failure, (2) assist pump inlet cannula obstruction and (3) excessive bleeding. The strategies developed or proposed to deal with these problems include, respectively: (1) biventricular assist for patients with concomitant right ventricular failure; (2) cannulation of the left atrium to avoid inlet cannula obstruction by the left ventricular wall and intraventricular septum; (3) more rapid selection of left assist candidates and more rapid implantation techniques to reduce the coagulopathy associated with prolonged cardiopulmonary bypass, and an effective autotransfusion system to augment blood replacement.

Adult↗
PubMed1978

Similarity of clinical and laboratory results obtained with microporous teflon membrane oxygenator and bubble-film hybrid oxygenator.

For 80 elective clinical cardiopulmonary bypasses we alternately used either a commercial microporous Teflon membrane oxygenator or a commercial hybrid bubble-film oxygenator. Setup time was a little longer with the membrane unit (20 minutes), but priming volume (2,250 ml) was the same. No problems were encountered with the hybrid oxygenator. However, despite our monitoring of additional variables, including shim and inlet pressure and recirculation flow, gas exchange abnormalities were encountered in 5 patients on whom the membrane oxygenator was used; in 4 of these cases the abnormalities were encountered prior to our recognition of the potential for occasional internal shunting with this device. There were no hospital deaths. When the two groups, matched except for oxygenator selection, were compared, there were no significant differences clinically or hematologically. For cardiopulmonary bypass of 2 hours or less, both oxygenators studied are definite improvements over previous silicone membrane and high-gas-flow bubble oxygenators. However, lower cost and reduced complexity favor the hybrid oxygenator.

Blood Glucose↗
PubMed1978

A new prosthesis for reconstruction of the left ventricular outflow tract.

A new left ventricular outflow tract prosthesis is described. It consists of a tightly woven Dacron graft with one end modified by being wrapped around a thin perforated stainless steel tube to form a rigid left ventricular insertion port and the other end anastomosed to a Hancock xenograft valved conduit for suture to the arterial system. The prosthesis is simple in design and flexible enough to permit anastomosis to any portion of the abdominal aorta. In addition, since the entire blood conduit consists of a porous woven arterial graft and a tissue valve, anticoagulants are not required. The prosthesis has been successfully employed in a 7-year-old boy who had undergone two previous open-heart operations for resection of a subaortic ring but who had persistent evidence of severe residual stenosis. We believe this conduit has advantages over present commercially available units.

Animals↗
PubMed1978

The development of pulmonary vascular obstructive disease after successful Mustard operation in early infancy.

Pulmonary vascular obstructive disease developed postoperatively in an infant with aortopulmonary transposition and intact ventricular septum who underwent a Mustard operation in 3 months of age. Preoperative catheterization had shown normal pulmonary artery pressures. Four months after surgery, catheterization showed pulmonary artery systolic pressure above the systemic level and a tortuous, attenuated pulmonary vascular tree visualized angiographically. Early corrective surgery may not preclude the development of pulmonary vascular obstructive disease in patients with aortopulmonary transposition.

Blood Pressure↗
PubMed1978

Late results of the subclavian flap procedure in infants with coarctation of the thoracic aorta.

Persistent stenosis or recoarctation occurs in 16 to 33% of infants who undergo repair of coarctation of the thoracic aorta by use of end-to-end anastomosis. This report describes the results in 12 infants of repair of coarctation of the aorta using a left subclavian artery flap procedure. Cardiac catheterization and cineangiography performed in four patients from 4 to 66 months following repair showed a 10 mm systolic gradient in one patient and no evidence of significant stenosis in any patient. The eight other patients have had recent sphygmomanometer pressures recorded from 1 to 29 months after repair. Four patients had no gradient while three patients had a systolic pressure gradient of 8, 10, and 12 mm Hg. Results suggest a smaller incidence of persistent stenosis or recoarctation following subclavian flap procedure than following end-to-end anastomosis. The subclavian flap operation provides an adequate aortic lumen with good growth potential. It is recommended as the operation of choice for infants with the most common form of coarctation of the aorta.

Aortic Coarctation↗
PubMed1978

Prolonged mechanical support of the left ventricle.

An interdisciplinary group has developed a left ventricular assist pump system composed of a modified sac type pump, a pneumatic power unit, and a synchronizer. The pump fills from the left ventricle and discharges into the aorta. The system was employed for left ventricular assistance in a series of 12 normal calves, with an average pumping period of 70 +/- 8 days. The system was then evaluated in a series of calves in whom profound left ventricular failure had been produced. These studies indicate that the assist pump is effective in supporting the circulation and completely unloading the left ventricle. The assist system has now been employed in four patients who could not be weaned from cardiopulmonary bypass following cardiac valve replacement. The assist pump supported the circulation in three instances. In one patient, the assist pump was employed for 8 days until left ventricular function had improved sufficiently to permit pump removal; the patient was subsequently discharged from the hospital.

Aged↗
PubMed1978

Determining arterial pressure, left atrial pressure and cardiac output from the left pneumatic drive line of the total artificial heart.

These data presented here demonstrate how careful analysis of mock loop testing can lead to useful measurements for long-term calf experiments. The accuracy of the data rae primarily dependent upon a valid circulatory system analog and good experimental technique. These methods of determining arterial pressure, left atrial pressure and cardiac output have allowed us to obtain recordds of these important parameters for periods as long as 100 days in calves with total artificial heart implantation. These methods have also enabled us to automatically control the artifical heart under conditions of rest, exercise and pharmacologic treatment with the use of only one external pneumatic drive line pressure transducer.

Animals↗
PubMed1978

A technique to assess fibrinogen, platelet and red cell kinetics in calves with artificial hearts or circulatory assist devices.

1. Normal data for routine hematologic studies including fibrinogen, VIIIAHF, AT III, and circulating platelet aggregates are reported for Holstein calves. 2. Therapy with warfarin, ASA, and dipyridamole does not alter these parameters such as VIIIAHF, AT III, or circulating platelet aggregates. 3. 75SeM can be used as an in vivo label to study the fibrinogen, platelet, and red cell kinetics simultaneously in calves. 4. Decreased VIIIAHF levels and decreased platelet survival are the most sensitive parameters to estimate the activation of coagulation in the animals with circulatory assist devices. 5. The total heart animals seem to have a significant decrease in fibrinogen and VIIIAHF levels as compared to normal and left ventricular assist animals. 6. Despite the use of warfarin and antiplatelet drugs, decreased platelet survival occurred in both the total heart and the left ventricular assist animals. Fibrinogen half life with 75SeM must be interpreted with caution until corrections for pool size, reutilization, and nonpeptide binding have been considered.

Animals↗
PubMed1977

The artificial heart. Progress and promise.

A multidisciplinary group has designed, fabricated, and evaluated an artificial heart. The heart consists of two smooth-surfaced sac-type pumps, two pneumatic power units, and an electronic control system. The artificial heart has been employed in 22 calves. A variety of problems have been encountered and overcome and a significant improvement in pump design has been made. As a result, a gradual increase in survival times has occurred. The last two calves in which the heart was tested lived for 60 and 42 days respectively. These animals ate well and gained weight. The ability of the control system to balance the output of the two pumps over long periods of time and to automatically increase cardiac output with treadmill exercise has been confirmed. No insurmountable problems in the development of the artificial heart have been identified. The date that an artificial heart will be available for clinical use depends on the availability of funds and on the tenacity of the investigators.

Animals↗
PubMed1977

Horizontal interventricular septum in congenital heart disease: surgical considerations.

A patient with complex congenital heart disease associated with a horizontal interventricular septum is described. In addition the ventricles were inverted, both great vessels arose from the left-sided right ventricle in the dextrotransposed position, and he had a ventricular septal defect of the type usually seen in endocardial cushion defect. Correction was performed using a Rastelli type procedure with good hemodynamic results.

Child↗
PubMed1977

Reconstruction of the right ventricular outflow tract with a conduit in congenital heart disease.

A series of five patients with complex cyanotic congenital cardiac malformations underwent surgical reconstruction of the right ventricular outflow tract using a Dacron conduit with a porcine aortic valve. All patients survived and all have shown clinical improvement. At cardiac catheterization postoperatively, a pressure gradient of between 20 and 50 mm Hg across the conduit was found in all patients. This surgical approach to patients necessitating reconstruction of the right ventricular outflow tract is effective and appears to have the best long-term results.

Adolescent↗
PubMed1977

The management of the lungs during cardiopulmonary bypass.

Many factors that contribute to the postextracorporeal pulmonary insufficiency have been recognized over the years that extracorporeal circulation has evolved. It is evident that more than one factor is the cause. For the present, a complex multifactoral problem appears to exist. Whether the unifying theory for this syndrome is related to abnormal organ perfusion, blood element destruction, microvascular phenomenon secondary to release of vasomotor substances or a combination of these remains to be determined. It is clear that all patients who undergo cardioplumonary bypass sustain some degree of pulmonary injury. Most lungs provide ample reserve, and adequate postoperative pulmonary care is sufficient to avoid morbidity related to the lungs. However, patients with severe forms of cardiopulmonary disease who require cardiopulmonary bypass require intraoperative pulmonary care as discussed herein to preserve maximum pulmonary function during the postoperative period.

Animals↗
PubMed1976

Quantitative evaluation of left ventricular bypass in reducing myocardial ischemia.

A controlled study was undertaken to evaluate the relationship between myocardial oxygen consumption (MVO2) and epicardial S-T segment improvement in an ischemic heart preparation during left ventricular (LV) bypass. Twelve mongrel dogs were prepared with left ventricular-aortic bypass, coronary sinus cannulation, and a multiple point epicardial electrocardiographic technique. The left anterior descending coronary artery was ligated low (Group I) or high (Group II) after baseline studies. After ischemic baseline studies, increasing degrees of LV bypass were performed at a constant mean aortic pressure and heart rate. The final infarct size was determined by the nitroblue tetrazolium staining technique. Group I--a significant reduction in the average (S-T) segment elevation occurred during 50 to 59 percent of LV bypass during which MVO2 was reduced 10.9 percent from controls. A maximum S-T reduction of 75 percent occurred during LV decompression during which MVO2 was reduced 52.8 percent from controls. The final infarct size for Group I was 9.8 +/- 0.9 Gm. per 100 Gm. of LV. Group II--a significant reduction in S-T segment elevation occurred only after 90 to 99 percent LV bypass was achieved during which MVO2 was reduced 28.1 percent from controls. LV decompression produced a maximum S-T reduction of 63 percent during which MVO2 was reduced 50.2 percent from controls. The final infarct size for Group II was 21.1 +/- 0.4 Gm. per 100 Gm of LV. This study indicates that larger degrees of bypass are required to decrease the ischemic areas encountered in larger infarctions. LV decompression is most beneficial in reducing ischemic myocardium surrounding large infarctions.

Animals↗