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Biomedical subjects

J N Cunningham

Publications and source records attributed to J N Cunningham.

At least 19 recordsLinked to original sources
PubMed1992

Intrathecal perfusion of an oxygenated perfluorocarbon prevents paraplegia after aortic occlusion.

A canine model was used to evaluate the effects of continuous intrathecal perfusion of an oxygenated perfluorocarbon emulsion on systemic and cerebral hemodynamics and neurologic outcome after 70 minutes of normothermic aortic occlusion. Twelve mongrel dogs were instrumented to monitor proximal and distal arterial blood pressure, cerebrospinal fluid pressure, spinal cord perfusion pressure, and somatosensory evoked potentials. The intrathecal perfusion apparatus consisted of two perfusing catheters, placed in the intrathecal space through a laminectomy, and a draining catheter percutaneously inserted in the cisterna cerebellomedullaris. The aorta was cross-clamped just distal to the left subclavian artery for 70 minutes. Animals were randomized into two groups: group 1 (n = 6) animals were treated with intrathecal perfusion of saline solution, whereas group 2 (n = 6) animals received oxygenated Fluosol-DA 20%. Data were acquired at baseline, during the cross-clamp period, and after reperfusion. Normothermic Fluosol or saline solution was infused at a rate of 15 mL/min beginning 15 minutes before cross-clamping and continued throughout the ischemic interval. There was no difference in proximal arterial blood pressure (97.2 versus 95.4 mm Hg; p > 0.05) or distal arterial blood pressure (14.6 versus 15.0; p > 0.05) between the two groups throughout the cross-clamp interval. Cerebrospinal fluid pressure rose significantly in both groups with the onset of intrathecal perfusion of either saline solution or Fluosol (7 +/- 1 versus 24 +/- 5 and 8 +/- 1 versus 40 +/- 4 mm Hg, respectively; p < 0.05). The rise in cerebrospinal fluid pressure was sustained throughout the perfusion interval in both groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Aortoventriculoplasty in the management of an infected Cabrol graft.

This report describes use of a modified aortoventriculoplasty (Konno procedure) for reoperation on a patient with prosthetic aortic valve conduit endocarditis. The modified Konno procedure was necessary to expose the mid-left ventricular outflow tract to reconstruct an aortic annulus.

Aortic Valve↗
PubMed1992

Effects of exsanguination and sodium nitroprusside on compliance of the spinal canal during aortic occlusion.

To evaluate the effects of sodium nitroprusside (SNP) and partial exsanguination (EXS) on systemic hemodynamics and cerebrospinal fluid dynamics, we monitored proximal and distal blood pressure (BP), cerebrospinal fluid pressure (CSFP), spinal cord perfusion pressure (SCPP), and compliance of the spinal canal (CSC) in 10 mongrel dogs during aortic cross-clamping of the descending thoracic aorta. CSC was measured by serial injections of 2 ml of saline solution into the cisterna cerebellomedullaris via a percutaneously placed catheter with simultaneous measurements of CSFP. Data were acquired at baseline (BL), during aortic cross-clamping with proximal hypertension (AXC), and after control of proximal hypertension with EXS and SNP. During the cross-clamp interval, mean proximal aortic pressure (PxBP) rose from 114 +/- 6 to 150 +/- 3 mm Hg (P less than 0.001), whereas mean blood pressure decreased to 88 +/- 5 and 82 +/- 4 mm Hg during the SNP and EXS intervals, respectively (P less than 0.05 vs BL). EXS and SNP were equally effective in controlling PxBP (82 +/- 4 vs 88 +/- 5 mm Hg, P greater than 0.05). Mean distal aortic pressure (DsBP) decreased from systemic values to 21.5 +/- 1.9 mm Hg during AXC, and to 12.4 +/- 1.0 and to 8 +/- 0.8 mm Hg during EXS and SNP, respectively (P less than 0.05 AXC vs EXS and SNP). SNP lowered DsBP significantly more than EXS, 8 +/- 0.8 vs 12.4 +/- 1.0 mm Hg (P less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

A multimodality approach lengthens warm ischemic time during aortic cross-clamping.

To evaluate the effects of exsanguination, cerebrospinal fluid drainage (CSFD), steroids alone and in conjunction with CSFD on spinal cord perfusion pressure (SCPP), and neurological outcome following 70 min of normothermic spinal cord ischemia, we monitored proximal (Px BP) and distal (Ds BP) aortic blood pressure, cerebrospinal fluid pressure, and somatosensory evoked potentials (SEP) in 29 mongrel dogs. In all animals Px BP during aortic cross-clamping was controlled with partial exsanguination (40-50% circulating blood volume). Dogs were randomized into four groups (gp): gp 1 (n = 6) control; gp 2 (n = 8) steroids only (methylprednisolone 30 mg/Kg 10 min before aortic occlusion and 4 hr later); gp 3 (n = 8) CSFD only; gp 4 (n = 7) steroids and CSFD. Partial exsanguination effectively controlled Px BP during aortic cross-clamping in all groups. After the statistically significant decrease from preclamp values, mean Px BP did not differ among groups (78.9, 81.2, 80.5, and 80.3 mm Hg, respectively, P greater than 0.05). Mean Ds BP decreased from systemic values to 12.6, 16.8, 16.7, and 17 mm Hg, respectively, after aortic occlusion (P less than 0.05); these values did not differ from one another. CSFP did not change significantly from its baseline value while the aorta was cross-clamped in gp 1; CSFP was significantly reduced to 6.2 mm Hg in gp 2, steroid-treated animals (P less than 0.05 vs gp 1); a further significant reduction in CSFP was noted in gp 3 and 4 undergoing CSFD (0.07 and 0.67 mm Hg, respectively, P less than 0.05 vs gp 1 and 2).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

One-year monkey heart xenograft survival in cyclosporine-treated baboons. Suppression of the xenoantibody response with total-lymphoid irradiation.

The shortage of cadaveric human organs for transplantation could be alleviated by the use of xenografts. Long-term (> one-year) survival of xenografts in humans or experimental animals has not been achieved with previous immunosuppressive protocols. Poor results in xenotransplantation compared with allotransplantation have been attributed to a more potent antibody response rather than to cell-mediated responses. To investigate these issues a concordant heterotopic cardiac xenograft model was developed in conjunction with cyclosporine and/or total-lymphoid irradiation. Concordant models permit examination of xenoantigen induced antibody and cell-mediated responses since preformed humoral factors (in discordant models) do not cause hyperacute rejection. Four groups of baboon recipients received cervical heart transplants from cynomolgous monkeys. Group I (n = 2), untreated, mean survival (MS) = 6 days; group II (n = 5), CsA and methylprednisolone, MS = 25 days; group III (n = 3), preoperative TLI, MS = 29 days; group IV (n = 6), preoperative TLI and CsA+MP, MS = 255 days (> 77, > 108, > 142, 184, > 480, 540 days). Heart xenografts of CsA-MP-treated recipients appear to be destroyed predominantly by antibody (IgM)-mediated processes whereas cell-mediated rejection is likely the major reaction in TLI-treated recipients. CsA-MP-treated recipients had early immunohistochemical evidence of antibody and complement-mediated rejection (deposition of IgM and complement but not IgG on heart xenografts). In contrast IgM and complement deposits were not detected on heart xenografts in TLI- and TLI-CsA-treated recipients. IgG xenoantibodies were only detected on the two rejected heart grafts of TLI-CsA-treated recipients. CsA-MP-treated recipients rapidly developed high xenoantibody titers (1:256 to 1:512) that immediately preceded rejection. In contrast, TLI-treated animals developed lower levels of xenoantibody (< or = 1:8) and TLI-CsA-treated recipients had no detectable xenoantibody during the initial three months after transplantation (and titers no greater than 1:8 thereafter.) The lack of xenoantibody was likely not due to a generalized inhibitory effect of the immunosuppressants on B cell function since all classes of serum immunoglobulins were in the normal range. Intragraft cytolytic lymphocyte activity was detected in rejecting TLI- and TLI-CsA-treated recipients but could not be detected in xenografts of CsA-MP-treated recipients. One explanation for these data is that TLI (either directly or indirectly) induces a state of specific B cell unresponsiveness to monkey xenoantigens, thereby preventing IgM mediated rejection in the third week after transplantation.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1991

Successful repair of a submitral left ventricular infected pseudoaneurysm.

Aneurysms of the left ventricle may be congenital or may occur after a myocardial infarction, trauma, or endocarditis. Infective endocarditis can cause destructive injury to the heart in various ways. This report describes the formation of an aneurysm of the left ventricle from trauma of a bacterial vegetation of the mitral valve. Early recognition by echocardiography and magnetic resonance imaging led to successful repair and prevented a catastrophic result.

Adolescent↗
PubMed1991

Mycotic aneurysm of the aortic arch with aortoesophageal fistula.

An elderly man presented with an aortoesophageal fistula (AEF) and underwent resection of a mycotic aneurysm of the aortic arch. After an initial success, the patient ultimately succumbed to mediastinal sepsis. The various approaches to combined aortic and esophageal pathology are presented with the recommendation for aortic replacement along with early removal of mediastinal contamination.

Aged↗
PubMed1979

Constant-pressure aortic root perfusion versus cardioplegia and hypothermia. Comparison of methods of myocardial protection.

Both coronary perfusion and hypothermic cardioplegia are widely used methods of myocardial protection during aortic valve replacement. A theoretical objection to coronary perfusion is that it is not synchronized with cardiac contractions. Accordingly, a special pump was designed to provide perfusion at a constant range of pressure. Twenty dogs were studied during 4 hours of bypass. In six dogs no manipulations were carried out and hearts were allowed to beat in a nonworking state. Seven dogs underwent 2 hours of aortic cross-clamping and constant-pressure aortic root perfusion. Seven dogs underwent 2 hours of uninterrupted aortic occlusion with myocardial protection being maintained by cold potassium-induced arrest, Contractility did not change significantly in any of the three groups. All animals demonstrated significant hyperemia after bypass but normal endocardial/epicardial flow ratios. Although compliance deteriorated in all groups, the most striking changes were seen following 4 hours of bypass alone or constant-pressure aortic root perfusion. Hypothermic potassium arrest, in contrast, provided a slightly greater degree of myocardial protection, perhaps both by limiting the degree of ischemic injury directly and by excluding the heart from the circulating blood and the pump oxygenator system.

Animals↗