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N A Yonan

Publications and source records attributed to N A Yonan.

14 recordsLinked to original sources
PubMed1996

Extended criteria for cardiac allograft donors: a consensus study.

BACKGROUND AND METHODS: To achieve a consensus regarding extending the current criteria for referring potential cardiac allograft donor, we sent a detailed questionnaire to all heart transplant surgeons in the United Kingdom. RESULTS: Replies representing the opinion of 16 heart transplant surgeons (88% response rate) suggest that the majority believe that donor age could be extended up to 55 years even in the absence of a coronary angiogram or echocardiogram. Family history of ischemic heart disease, history of hyperlipidemia or smoking, and brain death caused by paracetamole or barbiturates overdose were not considered prohibitive to cardiac allograft donation. Similarly, chest trauma, prolonged mechanical ventilation, pre-referral cardiac arrest or hypotension for any length of time, and nonspecific ST-segment elevation were not considered to be contraindications. By contrast, significant Q waves in a recent electrocardiogram, the presence of hepatitis C antibodies, pulmonary capillary wedge pressure more than 20 mm Hg, and dependency on multiple inotropic support were considered definite exclusion criteria. Donor hormonal resuscitation (T3-cocktail), insertion of a Swan-Ganz catheter, and direct measurement of intracavitary pressure at the time of retrieval were considered unnecessary by more than 80% of respondents. There was no consensus of opinion regarding the use of donors above the age of 55 years, brain death caused by carbon monoxide poisoning, history of diabetes mellitus, alcohol or drug abuse, systemic infections, electrocardiographic evidence of left ventricular hypertrophy, or the maximum dose of inotropic support required to maintain satisfactory hemodynamics. CONCLUSIONS: The number of potential cardiac allograft donors can be increased by extending the donor age to 55 years. Brain death caused by Paracetamole and barbiturate overdose may not prohibit organ donation.

Adolescent↗
PubMed1996

Orthotopic heart transplantation hemodynamics: does atrial preservation improve cardiac output after transplantation?

BACKGROUND: We have described an alternative technique for orthotopic heart transplantation (bicaval Wythenshawe technique) which maintains the right and left atrial anatomy and contractility. METHODS: Fifty patients were randomized into two groups: group A (n = 25) who had orthotopic heart transplantation using the bicaval Wythenshawe technique and group B (n = 25) who had conventional (Lower and Shumway) technique of orthotopic heart transplantation. We compared the cardiac output (measured by thermodilution technique) with atrial activation (AAI pacing) to cardiac output without atrial activity (VVI pacing) in both groups to identify any beneficial hemodynamic effects. All patients were studied the first and second weeks after transplantation. The inaccuracies of comparing cardiac output measurements caused by different loading conditions, inotropic state, and systemic vascular resistance were eliminated by using the patient as his or her own control. RESULTS: The difference between the measured cardiac output with atrial pacing and ventricular pacing was 1.42 +/- 0.44 L/min in group A in comparison with 0.32 +/- 0.4 L/min in group B (p = 0.001 Wilcoxon signed rank). The percentage of atrial contribution to the cardiac output in group A was 30% +/- 12% (standard deviation), 95% confidence interval in comparison with 7% +/- 9%, 95% confidence interval in group B. The mean stroke volume in group A was higher in sinus rhythm (65 +/- 19.2 ml) and atrial pacing (62 +/- 17.7 ml) compared with ventricular pacing (49.17 +/- 16.43 ml) p = 0.001. In group B no statistical difference was found between stroke volume measured with atrial (47.71 +/- 6.23 ml) or ventricular pacing (46.9 +/- 6.35 ml). CONCLUSIONS: We conclude that the bicaval technique of orthotopic heart transplantation preserve the atrial kick and its contribution to cardiac output early after transplantation.

Atrial Function↗
PubMed1995

Right lower lobe herniation after domino heart-lung transplantation.

We report 2 cases of trapping and incarceration of the right lower lobe in the left hemithorax after heart-lung transplantation with bicaval anastamoses (domino donors). This occurred despite confirmation of the normal anatomy at the time of implantation, before lung inflation. In 1 case this complication resulted in a right lower lobectomy 7 days after transplantation due to infarction and infection of the right lower lobe. These cases illustrate the importance of reexamining the anatomy after lung inflation, before chest closure.

Adult↗
PubMed1995

Orthotopic cardiac transplantation: a comparison of standard and bicaval Wythenshawe techniques.

We describe an alternative technique for orthotopic cardiac transplantation (bicaval Wythenshawe technique), which maintains the right and left atrial anatomy. We compared the new bicaval technique with the conventional (Lower and Shumway) technique of orthotopic cardiac transplantation to identify any beneficial physiologic and clinical outcomes resulting from maintaining the normal anatomy. Seventy-five patients were randomized on an alternate basis to two groups: group A (n = 40) had orthotopic cardiac transplantation with the bicaval technique and group B (n = 35) had conventional orthotopic heart transplantation. All patients were studied with transthoracic echocardiogram, endomyocardial biopsies, and measurement of intracardiac pressures 1, 4, and 12 weeks after transplantation. There were no statistically significant differences in the demographic profile, ischemic time, bypass time, implantation time, transpulmonary gradient, or pulmonary vascular resistance between the two groups. The hemodynamic data were collected in the absence of histologic signs of rejection. In group A right atrial pressure (mean 3.6 mm Hg) was significantly lower (p < 0.03) than in group B (mean 8.8 mm Hg). The right atrial a wave was recorded in 38 patients in group A compared with seven patients in group B (p = 0.041). Atrial tachyarrhythmias occurred in two patients in group A compared with 11 in group B (p < 0.016). Temporary pacing was required in 10 patients in group A and 16 patients in group B (p = 0.034). Four cases of mitral regurgitation (all mild) were detected in group A in comparison with 12 cases (10 mild, 2 severe) in group B (p = 0.008). The mean ejection fraction in the first week after transplantation was 58% in group A and 46% in group B (p = 0.5). In the first 3 months the need for diuretics was less in group A (mean dose 80.8 mg furosemide daily) than in group B (mean dose 134 mg furosemide daily in the first week increasing to 160 mg furosemide daily). Hospital stay was shorter in group A (mean 23 days) than in group B (mean 27 days) (p < 0.015). There were no early deaths as a result of right ventricular failure in group A (n = 0/40) compared with four (n = 4/35; 9%) in group B (p < 0.034). This difference suggests that bicaval orthotopic cardiac implantation is associated with a lower right atrial pressure, a lower likelihood of atrial tachyarrhythmias, less need for pacing, less mitral incompetence, a lower diuretic dose, and a shorter hospital stay.(ABSTRACT TRUNCATED AT 400 WORDS)

Echocardiography↗
PubMed1994

Rejection in heart transplantation strongly correlates with HLA-DR antigen mismatch.

It is well established that incompatible HLA antigens presented by donor tissue readily evoke an immune response. Prospective HLA matching policies, widespread in European kidney transplant centers have reduced the level of HLA mismatching and have significantly improved graft survival. The influence of HLA incompatibility in heart transplantation remains controversial, and prospective HLA matching is seldom achieved. We examined the role of HLA antigen mismatching on transplant rejection by analyzing 2569 endomyocardial biopsies (EMB) from 157 consecutive orthotopic heart transplants performed from April 1987 to August 1993 in our own center. Biopsies were graded according to the accepted International Classification, with grade 2 and higher indicating rejection. Among 91 patients who received a 2 HLA-DR mismatch transplant 34% of 1624 biopsies analyzed were graded as > or = 2. This frequency fell to 29% of 797 biopsies for 53 patients with a one-HLA-DR mismatch and to 18% of 148 biopsies for 13 patients in the zero-HLA-DR-mismatch group (P < 0.00005). No significant effect on EMB grade frequencies was observed using the same method of analysis with transplants mismatched at the HLA-A or HLA-B loci apart from analysis of HLA-B matched transplants at 3 months posttransplant (P = 0.02). The close linkage of the HLA-B and HLA-DR loci may account for this observation. The results of this study show that heart transplants matched at the HLA-DR locus have a significantly reduced incidence of EMB grades indicative of rejection requiring augmented immunosuppressive therapy. We propose that prospective HLA-DR matching should be adopted for allocation of donor hearts for more efficient use of this precious and limited resource.

Adolescent↗
PubMed1993

An alternative surgical technique in orthotopic cardiac transplantation.

Forty patients underwent orthotopic cardiac transplantation at Wythenshawe Hospital between May 1991 and November 1992. Twenty patients had transplantation using an alternative technique that preserves the shape of the left atrium and leaves the right atrium intact (group A). The remaining twenty had conventional transplantation using the technique described by Lower and Shumway (group B). The patients were randomized to either the new or the conventional technique on an alternate basis. There was no mortality in group A, but two patients in group B developed right ventricular failure and died. Two patients in each group developed nodal rhythm and all four recovered sinus rhythm. Echocardiography and Doppler velocimetry at the transvalvular level confirmed normal atrial function in group A with erratic atrial contraction wave in group B. There was also slightly lower incidence of mitral and tricuspid valve regurgitation in group A than in group B. The improved atrial function in group A may play a part in the prevention of right sided failure following cardiac transplantation.

Echocardiography↗
PubMed1991

Effect of intra-aortic balloon counterpulsation on right-left shunt following right ventricular infarction.

Intra-aortic balloon counterpulsations decrease the left ventricular end-diastolic pressure and, subsequently, the left atrial pressure in patients with impaired myocardial function following myocardial infarction. This paper reports a case of right ventricular infarction in a patient with patency of the oval foramen where the use of intra-aortic balloon counterpulsation led to the perpetuation of the right-to-left shunt.

Coronary Artery Bypass↗
PubMed1990

Technique of dissecting the internal mammary after using the Moussalli bar.

Since 1985 we have utilised a simple technique for dissecting the internal mammary artery (IMA) prior to coronary artery bypass surgery. The technique involves the use of a stainless steel bar (Moussalli bar) in conjunction with a Holmes Sellors sternal spreader. We have used this technique to dissect more than 2000 IMAs in patients of varying body weight and muscle build without significant complications.

Cardiology↗
PubMedDate not supplied

Retrograde pulmonaryplegia for lung preservation in clinical transplantation: a new technique.

Pulmonary artery flush with modified Euro-Collins solution is currently used by many centers for lung preservation. Two limitations with this technique have been that pulmonary artery vasoconstriction necessitates pretreatment of the donor with a prostaglandin and that bronchial circulation, which supplies important nutrients to the intrapulmonary airways, has been ignored. Retrograde pulmonaryplegic solution delivered through the left atrium can perfuse the dual bronchial and pulmonary circulation; furthermore, pulmonary arterial constriction will not affect distribution and may actually enhance it. The technique was used in three successive patients who underwent heart-lung transplantation. Postoperative oxygenation remained excellent; no implantation response occurred, and all three patients were extubated in less than 24 hours. Retrograde pulmonaryplegia offers a simple technique of perfusing both the pulmonary and the bronchial circulation.

Adolescent↗
PubMedDate not supplied

Early pulmonary vein thrombosis after single lung transplantation.

Pulmonary venous obstruction after single lung transplantation may be mistaken for reperfusion injury or myocardial dysfunction. Complete obstruction of one of the major pulmonary veins will result in hemorrhagic infarction of the affected lobe within 4 to 6 hours, limiting the option of treatment to resection (lobectomy) or retransplantation. Early diagnosis is therefore essential. Transesophageal echocardiography can show the pulmonary venous anastomosis and, combined with color flow and Doppler imaging, offer a quick and reliable method of diagnosis. Prevention of this complication entails harvesting an adequate margin of left atrial tissue around the pulmonary vein orifices, meticulous surgical anastomosis, and the use of anticoagulation in the presence of a thrombogenic tendency in the recipient.

Adult↗