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Biomedical subjects

J C Norman

Publications and source records attributed to J C Norman.

At least 19 recordsLinked to original sources
PubMed1991

Laser assisted balloon angioplasty in peripheral vascular surgery: a preliminary report.

Laser/balloon thermal angioplasty has proven to be a valuable adjunct in our management of peripheral vascular disease. The initial trials have produced a 77% success rate, a 3% incidence of complications, and no morbidity. Patient acceptance has been high and the return to prior activities in less than 1 week is an appreciated advantage. Laser/balloon angioplasty expands the armamentarium of the vascular surgeon and makes possible broader applications of standard vascular surgical techniques.

Aged↗
PubMed1991

A unique inlet [the ascending aorta] for extra-anatomic bypass of infected arterial prostheses.

Infection is the most dreaded complication associated with implantation of a prosthetic arterial graft. The reported incidence of primary graft infection varies from 1.3% to 6.0%, with a mortality rate from this complication as high as 75%. Although remote bypass followed by complete removal of the infected prosthesis has proven to be a satisfactory method of treatment, in certain instances remote bypass alone is not feasible and other modes of surgical treatment must be employed. Such conservative methods of management of infected aorto-iliac-femoral prosthesis sometimes irradicate infection. The only certain cure, however, is obtained by totally removing the graft. And the success of extra-anatomic axillofemoral techniques has led to its extended use. The addition of a cross-limb on an axillo-unilateral femoral graft to form an axillobilateral femoral graft was described by Sauvage and Wood, reasoning that the higher flow rate in the axillary limb of the axillobilateral femoral graft would result in an improved patency rate compared with that of axillounilateral femoral grafts. Additionally, both medial (obturator foramen) and lateral extra-anatomic remote bypass of infected femoral prosthesis have been used, successfully. The current case illustrates the complexity of management, once sepsis occurs. It further focuses on groin, retroperitoneal and bilateral axillo-femoral tract infection with prolonged (apparently innocuous) graft exposure and finally points out the utility of the ascending aorta as an alternative extra-anatomic inlet to perfuse the lower extremities.

Aged↗
PubMed1979

Comparative study of erythromycin, amoxicillin and ampicillin antimicrobial activity against human respiratory tract pathogens.

An in vitro test system was used to compare the antimicrobial activity of erythromycin, amoxicillin and ampicillin against respiratory tract pathogens isolated from man. The minimum inhibitory concentrations (MICs) of fresh clinical isolates of Streptoccus pyogenes, Streptocuccus pneumoniae, Staphylococcus aureus and Haemophilus influenzae to the macrolide and penicillins ranged between 0.01 and 0.9 microgram/ml. The microbes were exposed to each antibiotic for approximately 3 h at 1x,2x and 5x the relevant MIC. Irreversible surface defects and intracellular lesions were resolved by scanning and transmission electron microscopy in all antibiotic-treated bacterial species, irrespective of the antimicrobial used. In each case, inhibition of growth was recorded by turbometric assay; no significant difference was observed among the declining slopes of post-dosing growth curves for either erythromycin-, amoxicillin- or ampicillin-treated pathogens. The experimental observations show that the onset of antimicrobial activity and the bactericidal effectiveness of equipotent concentrations of erythromycin, amoxicillin and ampicillin were comparable in this study. The results complement previous clinical, bacteriologic and ultrastructure studies in vivo and demonstrate the contribution of the combined in vivo/in vitro study design for better understanding of antimicrobial activity in human respiratory tract infections.

Amoxicillin↗
PubMed1979

Efficacy of nitroprusside therapy in postcardiotomy low-output syndrome necessitating intra-aortic balloon counterpulsation.

Serial hemodynamic measurements were obtained before, during, and after nitroprusside therapy over a 24 hour period in 19 patients requiring intra-aortic balloon pumping (IABP) for successful weaning from cardiopulmonary bypass. Nitroprusside, administered in doses ranging from 0.5 to 5 micrograms/kg/min, effected significant reductions in mean aortic pressure and systemic vascular resistance within 20 to 30 minutes. Mean aortic pressure decreased from 108 +/- 22 mm Hg to 85 +/- 27 mm Hg (p less than 0.005). Systemic vascular resistance decreased from 2,705 +/- 1,072 to 1,942 +/- 823 dynes sec cm-5 (p less than 0.005). 2n response to nitroprusside-induced decreases in left venticular afterload, cardiac indes increased from 1.83 +/- 0.58 to 2.04 +/- 0.54 L/min/m2 (p less than 0.025). Pulmonary capillary wedge pressure (PCW), right atrial pressure, right and left ventricular minute work indices, and the rate-pressure products did not change, indicating that nitroprusside administration during IABP further increased cardiac output without increasing ventricular filling pressure, ventricular work, or indices of myocardial oxygen consumption. The data suggest that nitroprusside, in conjunction with volume loading to optimal preload levels (PCW = 15 to 18 mm Hg), augments ventricular performance in postcardiotomy low-output syndrome by lowering impedance to left ventricular ejection through a direct dilator effect on vascular smooth muscle, without a direct effect on cardiac muscle. Thus it is a valuable pharmacologic adjunct during mechanical (IABP) support of the failing circulation.

Blood Pressure↗
PubMed1978

Total support of the circulation of a patient with post-cardiotomy stone-heart syndrome by a partial artificial heart (ALVAD) for 5 days followed by heart and kidney transplantation.

A patient with acute bacterial endocarditis in whom ischaemic contracture of the left ventricle (stone-heart syndrome) developed during aortic and mitral valve replacement had an emergency implantation of an intracorporeal partial artificial heart (an abdominal left-ventricular assist device of ALVAD). This device functioned as a total artificial heart for nearly 6 days, while a donor heart for transplantation was sought. The ALVAD was then removed, and the patient received allografts of a heart and a kidney. The transplanted heart functioned well, but the patient died 15 days later from gram-negative sepsis. There was no evidence of cardiac or renal allograft rejection.

Acute Disease↗
PubMed1978

Partial artificial heart (ALVAD) use with subsequent cardiac and renal allografting in a patient with stone heart syndrome.

The abdominal left ventricular assist device (ALVAD) is an order of magnitude more effective than conventional intra-aortic balloon pumping (IABP) in unloading and providing circulatory support to the failing left ventricle. This is a report of a unique case which demonstrates that in the absence of pulmonary vascular obstruction or constriction, the ALVAD can substitute for both left and right heart function. A 21-year-old patient with a congenital bicuspid aortic valve developed acute valvular endocarditis which rapidly progressed to congestive heart failure. An operation was undertaken, the mitral and aortic valves were excised and replaced by porcine heterografts, and a fistula from the right sinus of Valsalva to the right ventricle was closed. When coronary circulation was restored, irreversible ischemic contracture of the left ventricle, or "stone heart" syndrome, developed and emergency ALVAD or partial artificial heart implantation was effected. This device functioned as a total artificial heart for nearly six days, while a donor heart was sought. The patient then underwent removal of the ALVAD and cardiac and renal allografting. The transplanted heart functioned well, but the patient expired fifteen days later from gram-negative sepsis.

Adult↗
PubMed1978

Molecular, microscopic, microstructural and mechanical methods of analyzing pseudoneointimal linings within partial artificial hearts in man and the calf.

Ex vivo molecular, microscopic (cellular), microstructural and mechanical methods have been utilized to evaluate biologic, blood-interfacing linings (pseudoneointimal) formed on textured, fibril-flocked pumping surfaces within abdominal left ventricular assist devices (ALVADs) on partial artificial hearts. Thus far, seventeen human and twenty bovine pseudoneointimal linings (1--28 day pumping durations) have been evaluated by these methods. The results indicate that pseudoneointima begins developing within 24 hours after contact of the pumping surface with blood and is well developed at five days. The linings exhibit surface immunofluorescent fibrinogen activity, viable surface macrophages and histiocytes and scattered erythrocytes at ALVAD removal. Structurally similar linings (20 micrometer to 500 micrometer in thickness) develop in calves and in man. Mechanically, pseudoneointima is a stable, adherent, highly compliant, isotropic structural material. It is linearly elastic and strain-rate independent, with small viscous energy losses under physiologic strains. The methods employed for the evaluation of pseudoneointima provide useful information to determine the suitability of textured or rough surfaces for blood interfacing. The cumulative results indicate that the textured surface approach is useful for intermediate-term clinical ALVAD utilization.

Animals↗
PubMed1978

Intra-aortic balloon pumping: theory and practice. Experience with 325 patients.

Intra-aortic balloon pumping to support the failing circulation is now an accepted therapeutic modality. The device is simple. Insertion can be accomplished rapidly and efficiently in emergency rooms, coronary care units, cardiac catheterization suites and operating rooms, preoperatively, intraoperatively and postoperatively. The hemodynamic effects are immediate and predictable, and the accruing clinical results show increasing survival and hospital discharge rates. In these institutions, mechanical support of the circulation by this and more advanced methods has been formalized within the responsibility of a Circulatory Support Service. The purpose of this report is to summarize some observations and analyses which have been made during care of 325 consecutive postcardiotomy and/or postinfarction cardiogenic shock patients. Historical, theoretical, basic, and applied aspects and current results are included. Foremost are the straightforward concepts of considering the heart as a pump, the failing heart as a failing pump and intra-aortic balloon pumping as a temporary intravascular, auxiliary pump, capable of stabilizing or reversing that failure if utilized early in its evolution.

Adult↗