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Biomedical subjects

R W Emery

Publications and source records attributed to R W Emery.

At least 109 records · Page 6Linked to original sources
PubMed1979

Pulmonary valve replacement with a porcine aortic heterograft.

Pulmonary valve replacement is an uncommon surgical procedure, yet lifesaving when performed under the appropriate circumstances. The patient reported on here had the classic indications for valve replacement: increased pulmonary vascular resistance and associated pulmonary valve incompetence following repair of a congenital heart defect resulting in right heart failure and secondary tricuspid insufficiency. A review of the literature provides the basis for the decision to replace the pulmonary valve with a glutaraldehyde-preserved porcine heterograft.

Animals↗
PubMed1979

The Bezold reflex: a special case of the left ventricular mechanoreceptor reflex.

Our previous finding that increasing myocardial contractility caused reflex systemic hypotension, the left ventricular (LV) mechanoreceptor reflex, suggested that the classical Bezold reflex (systemic hypotension and bradycardia after intracoronary administration of veratrum alkaloids) may be initiated by these same LV mechanoreceptors. In our working LV preparation with the coronary and systemic circulations isolated and perfused separately, intracoronary injection of veratrum alkaloids, like that of catecholamines or ouabain, had a positive inotropic effect which produced the hypotensive response typical of the LV mechanoreceptor reflex. To test directly if veratridine's positive inotropic effect initiates the Bezold reflex, verapamil, which blocks the slow Ca(2+) channels of myocardial cells but leaves intracardiac nerves unaffected, was injected by the intracoronary route to prevent the increased contractility from intracoronary injection of veratridine which also abolished the reflex hypotension, demonstrating conclusively that increasing myocardial contractility and thereby activating LV mechanoreceptors but not chemoreceptors initiates the Bezold reflex. Contrariwise, decreasing contractility or cardiac asystole by administration of tetrodotoxin, verapamil, or EDTA resulted in an increase in the systemic resistance, indicating that changes in the magnitude of the stimulus initiating the LV mechanoreceptor reflex (i.e., changes in myocardial contractility) lead to directionally opposite changes in peripheral resistance, as in the sino-aortic mechanoreflexes. Thus, it is concluded that the Bezold reflex is a special case of the LV mechanoreceptor reflex. The latter, by means of feedback mechanisms, functions normally by continuously matching the peripheral resistance to the LV contractile state so as to maintain the arterial pressure constant, thereby playing an important role in blood pressure regulation.

Animals↗
PubMed1979

A new cardiac prosthesis: the St. Jude Medical cardiac valve: in vivo results.

The St. Jude Medical cardiac valve prosthesis is a low profile, lightweight, bi-leaflet, central-flow device constructed entirely of pyrolytic carbon. In vivo testing was performed in 24 cows in which the tricuspid valve (n = 14) or mitral valve (n = 10) was replaced by a St. Jude Medical prosthesis with a 26 mm tissue annulus diameter. Eight animals died in the operative period. The 16 surviving animals were sacrificed at 4, 8, 12, or 18 weeks. There were no valve-related deaths nor mechanical valve failures. Anticoagulation was not used in the postoperative period during which time monthly laboratory parameters were obtained including hemoglobin, hematocrit, white cell count, red cell count and indices, lactic acid dehydrogenase, serum haptoglobin, and, additionally at sacrifice, platelet and red cell morphology. Values indicated this prosthesis did not cause hemolysis. At sacrifice the pulmonary arterial tree and peripheral organs showed no evidence of thromboemboli. There was smooth endocardial ingrowth on all valve sewing rings. One valve had thrombus formation on the valve sewing ring. Nine animals were anesthetized prior to sacrifice and underwent open cardiac catheterization. Ventriculography (n = 6) showed minimal transvalvar reflux, and atriograms (n = 6) demonstrated central flow. Transvalvar gradients were 0 to 22 mm Hg (n = 9). One valve of an 18-week tricuspid implant was examined for wear; valve life was calculated to be greater than 2500 years. These data in conjunction with in vitro test results justify clinical trial of the St. Jude Medical prosthesis.

Animals↗
PubMed1979

St. Jude Medical cardiac valve prosthesis: in vitro studies.

The St. Jude Medical cardiac valve prosthesis is an all-pyrolitic carbon, bileaflet, low profile, central flow device. Prior to clinical use on intensive program of in vitro and in vivo testing was undertaken. Simulated radiographic studies determined that the tungsten impregnation needed to make the valve leaflets radiopaque was 0.013 inch. Steady-state flow and pulse duplicator studies demonstrated a high ratio of flow orifice to tissue anulus diameter with low transvalvular pressure gradients. Regurgitation was found to be acceptable. Flow visualization revealed central flow through all three flow orifices with minimal turbulence and vorticeal current formation. In vitro comparison with other available cardiac valve devices of various sizes demonstrated superior hemodynamic performance of the St. Jude Medical cardiac valve.

Aortic Valve↗
PubMed1978

Adjuvant radiation therapy in colorectal carcinoma.

A series of sixty-five patients with adenocarcinoma of the rectum and rectosigmoid is reviewed. Thirty-two patients had surgery alone, fourteen patients underwent postoperative radiation therapy, and nineteen patients underwent preoperative radiation therapy. A moderate dose program of 4,000 to 4,500 r was used. The postoperative treatment group had a higher incidence of stage C lesions and a higher recurrence rate, but there were no statistically significant differences in survival. Postoperative radiation therapy in patients with stage C lesions did not prolong life and is of little benefit. The preoperative treatment group tolerated the radiation very well, and there were no major complications. Eight patients underwent anterior resections in irradiated fields. Two minor anastomotic leaks subsequently healed spontaneously. There were no pelvic recurrences in the preoperative treatment group, and the incidence of lymph node metastases was 26% as opposed to 41% in controls. We conclude that preoperative moderate dose radiation is not associated with increased risk of morbidity or mortality. It may be useful in reducing the incidence of lymph node metastases and pelvic recurrence. The effect on survival is not determined in this study.

Adenocarcinoma↗
PubMed1978

Placement of pericardial drainage tube for the treatment of pneumopericardium in the neonate.

A method for resolving the life-threatening complication of neonatal pneumopericardium is described. In patients suspected of having this complication, needle aspiration of the pericardial sac should be performed to confirm the diagnosis. Then a tube should be inserted directly into the sac, attached to continuous-suction drainage, and allowed to remain in place until positive end-expiratory pressure is discontinued. The technique has not been associated with morbidity, mortality, or recurrence of pneumopericardium.

Drainage↗
PubMed1978

Ball variance and fracture of mitral valve prosthesis causing recurrent thromboemboli.

This report documents the ninth case of ball variance in a Starr-Edwards Model 6000 mitral prosthesis occurring 10 years, 9 months after implantation. It is the fourth case of fracture of a mitral ball of any type. As this case illustrates, the presence of ball variance in the mitral position may be subtle. One must carry a high index of suspicion if the diagnosis is to be made and treatment undertaken before catastrophic events take place. The incidence of ball variance is likely to increase with the length of implantation. We recommend surgical replacement of the defective prosthesis immediately upon confirmation of diagnosis.

Adult↗
PubMedDate not supplied

The Nimbus Hemopump: a new left ventricular assist device that combines myocardial protection with circulatory support.

Recent advances in hemodynamic support can allow patients at high risk for cardiovascular collapse to become candidates for coronary interventions. A new axial blood flow pump has recently been developed and made available for clinical testing. This intravascular pump utilizes an Archimedes screw pump rotating at 25,000 rpms to provide a flow of 2 to 3.5 liters/minute. The 7 mm inlet cannula of the cable driven pump is delivered across the aortic valve. The pump discharges blood into the descending aorta. This design does not require a membrane oxygenator. This pump would be expected to: 1) provide circulatory support irrespective of heart arrhythmias; 2) provide left ventricular unloading and 3) lack the fluid and coagulation abnormalities of prolonged cardiopulmonary bypass. This unique device offers great promise to the interventional cardiologist.

Angioplasty, Balloon, Coronary↗
PubMedDate not supplied

Current functional status of Symbion total artificial heart recipients after transplantation.

This multicenter study examines long-term data from the five most experienced North American centers (> 8 total artificial heart [TAH] implants), investigating the functional status of 37 patients who received a Symbion TAH followed by a heart transplant (TX) with post-TX survival > or = 1 year. Primary indications for TAH use included acute cardiogenic shock in 38% (14/37) of patients and deterioration while on the TX waiting list in 35% (13/37). At the time of this study, 86% (32/37) of patients were alive, 94% of whom were functioning at a New York Heart Association (NYHA) classification of I (75% [24/32]) or II (19% [6/32]). NYHA classification before death was I for all five patients who died 40 +/- 17 (r = 14-58) months after transplant. Of the 32 surviving patients, 47% (15) were working, 16% (5) were retired, 12% (4) chose not to work, and 9% (3) were in school. The remaining 16% (5) were unable to work due to surgical limitations. After TX, significant infections occurred in 81% (26/32) of patients and rejection in 72% (23/32). At 1 year after TX, creatinine was within normal limits (< or = 1.4 mg/100 ml or 65-125 mol/L) for 41% (13/32) of patients, 1-2 times normal for 56% (18/32), and > 2 times normal for 3% (1/32). Although TAH is not required for most patients awaiting TX, the device allows excellent long-term functional status in patients otherwise at risk for death. No long-term problems related to the use of temporary mechanical circulatory support were found.

Adolescent↗
PubMedDate not supplied

Registry report. Use of total artificial hearts: summary of world experience, 1969-1991.

Eleven models of total artificial hearts (TAHs) have been used for transient or permanent circulatory support in patients with failing hearts. From April 4, 1969 to July 1, 1991, 230 TAHs were used in 226 patients (four patients received a second TAH) at 39 centers worldwide. Five patients received a Symbion TAH as a permanent circulatory support device; the remaining 221 received TAHs as bridges to cardiac transplantation. The principal investigators received written requests for demographic and clinical information after each implant and annually thereafter to assess survival. The mean patient age (+/- SD) was 43 +/- 12 years (range, 13-69 years); 88% of patients were men. The primary indications for implantation were deterioration while on a transplant waiting list (34%) and acute cardiogenic shock (33%). The duration of implantation ranged from < 1 to 603 days; 65% received heart transplants. The incidence of infection and embolic events occurring during implantation times were 36% and 9%, respectively (stroke, 5%; transient ischemic attacks 4%). Most deaths were caused by sepsis (33%) and multiorgan failure (32%) during the implantation period; sepsis (36%) and rejection of the donor heart (19%) were responsible for most deaths in patients who died after transplantation. The 1 year survival rate was 37% for all patients receiving a device and 50% for those who received a transplanted organ. In the overall Symbion TAH population (187 patients), 40% survived 1 year and 56% of the transplanted group survived 1 year; 39 non-Symbion TAH implants resulted in one long-term survivor (3%).(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMedDate not supplied

Summary of the clinical use of the Symbion total artificial heart: a registry report.

Several models of total artificial hearts have been used for transient or permanent circulatory support in patients with decompensation. The most successful and widely used device, however, has been the Symbion total artificial heart. From Dec. 12, 1982, to Jan. 1, 1991, 180 Symbion total artificial hearts were implanted in 176 patients in 28 centers. Five patients received a Symbion total artificial heart as a permanent circulatory support device, whereas 171 patients received the device as a bridge to heart transplantation. Of the 175 bridge devices (171 patients) 141 were Symbion J7-70 hearts and 34 were Symbion J7-100 hearts. Four patients received two total artificial hearts, the second one after the failure of a transplanted heart because of either rejection (two patients) or donor heart failure (2 patients). Most of the recipients were males (152). The age was 42 +/- 12 years (mean +/- SD) with a weight of 74 +/- 14 kg. The most common indications for implantation included deterioration while awaiting heart transplant (36%) and acute cardiogenic shock (32%). The cause of heart disease was primarily ischemic (52%) and idiopathic (35%) cardiomyopathy. Duration of implantation ranged from 0 to 603 days (mean 25 +/- 64 days). One hundred three (60%) patients had the device less than 2 weeks, 37 (22%) between 2 to 4 weeks and 31 (18%) more than 4 weeks. Complications during implantation included infection (37%), thromboembolic events (stroke 7%, transient ischemic attack 4%), kidney failure requiring dialysis (20%), bleeding requiring intervention (26%), and device malfunction (4%). Of the 171 patients, 118 (69%) underwent orthotopic heart transplantation. Actuarial survival for all patients with implants was 62% for 30 days and 42% for 1 year, and for patients with transplants was 72% for 30 days and 57% for 1 year. The main causes of death were sepsis (33%), multiorgan failure (21%), and posttransplant rejection (10%). The results indicate a relative success of this treatment for patients with an otherwise fatal prognosis. Moreover, as the demand for donor organs far exceeds availability, continued investigation of total artificial hearts is justified.

Actuarial Analysis↗