Paroxysmal Atrioventricular Block in a Relatively Young Patient with COVID-19.

Cardiac involvement has been reported in patients with coronavirus disease 2019 (COVID-19). We herein report a 41-year-old man who presented with recurrent paroxysmal atrioventricular block without showing significant cardiac injuries or comorbidities. The patient was diagnosed with COVID-19 and admitted to our hospital, where he was noted to have paroxysmal atrioventricular block. Cardiac biomarkers, echocardiography, and cardiac magnetic resonance imaging findings were fairly normal. An endomyocardial biopsy performed before the implantation of a permanent pacemaker revealed mild myocardial fibrosis without inflammatory infiltrates. The unusual myocardial involvement of the novel coronavirus was suspected.

[Infarct Exclusion Repair and Mitral Valve Replacement for Inferior Postinfarction Ventricular Septal Perforation].

We performed infarct exclusion repair of ventricular septal perforation(VSP) in a 63-year-old woman who was diagnosed with acute myocardial infarction(AMI) of the inferior wall. As VSP existed behind a fragile posterior papillary muscle, we excised the papillary muscle and sutured a bovine pericardial patch to exclude the infarct area of the whole septum and a part of the inferior wall. Mitral valve replacement and coronary artery bypass were also performed. The postoperative course was uneventful. There was no residual shunt and the left ventricular function was preserved. Selection of surgical procedures taking account of complete closure of VSP is important.

Impact of first documented rhythm on cost-effectiveness of extracorporeal cardiopulmonary resuscitation.

OBJECTIVES: Recommendations for extracorporeal cardiopulmonary resuscitation (ECPR) state that appropriate patient selection is important for the sake of efficacy and cost-effectiveness of ECPR. It is not known whether first documented rhythm plays a prominent role in economic outcomes of patients with cardiac arrest who received ECPR. METHODS AND RESULTS: We reviewed the medical records of 120 consecutive patients who received extracorporeal membrane oxygenation (ECMO) assisted CPR due to refractory circulatory collapse between 2008 and 2016 in Urasoe General Hospital. The patients presented with ventricular fibrillation or pulseless ventricular tachycardia (VF/VT; n = 59, 49.2%) or with asystole or pulseless electric activity (ASY/PEA; n = 61, 50.8%) as the first documented rhythm. Multivariate logistic regression analysis identified shorter duration from collapse to ECMO initiation (odds ratio, 1.95 per 10 min; 95% confidence interval, 1.32-2.89, p = 0.001), bystander CPR (odds ratio, 5.53; 95% confidence interval, 1.36-22.5, p = 0.017), and first documented rhythm of VF/VT (odds ratio, 3.93; 95% confidence interval, 1.30-11.8, p = 0.015) as clinical predictors for neurologically intact survival. Total hospital cost per life saved by ECPR for ASY/PEA was approximately twice that for VF/VT ($213,656 vs. $101,669). ECPR yielded Quality adjusted life years (QALYs) of 3.32 at a mean total cost of $39,634 for VF/VT and QALYs of 1.17 at a mean cost of $35,609 for ASY/PEA. The cost per QALYs was $11,081 for VF/VT and $29,447 for ASY/PEA. The incremental cost-effectiveness ratio of ECPR vs. conventional CPR was estimated to be $ 16,246 per QALY gained. CONCLUSION: ECPR for patients presenting with VF/VT was found to be highly cost-effective and ECPR for patients presenting with ASY/PEA was borderline cost-effective.

Comparison of neointimal coverage and extra-stent lumen between sirolimus and everolimus-eluting stent using optical coherence tomography.

The external lumen of a stent [defined as extra-stent lumen (ESL)] assessed by optical coherence tomography (OCT) may be related to the risk of thrombus formation after sirolimus-eluting stent (SES) implantation. An everolimus-eluting stent (EES) might provide relatively minimal inflammatory reaction and appropriate neointimal coverage. The purpose of this study was to compare the neointimal thickness and ESL between SES and EES. Patients who underwent OCT examination more than 7 months after either SES or EES implantation were enrolled. Stent area (SA), lumen area (LA), neointimal area (NIA) and neointimal thickness (NIT) of each strut were measured at 1-mm intervals between stented segments. The area, angle (summation per cross-section) and depth (maximum distance from adjacent vessel surface to the outline of stent) of ESL were analyzed. A total of 49 lesions were included (SES n = 20, EES n = 29). Mean follow-up period was 11 months. A total of 998 cross-sections and 9874 struts were analyzed. There were no differences in stent area, lumen area and neointimal area (SA: 6.01 ± 1.60 vs. 6.02 ± 1.40 mm(2), p = 0.572, LA: 5.37 ± 1.52 vs. 5.29 ± 1.34 mm(2), p = 0.692, NIA: 0.64 ± 0.49 vs. 0.72 ± 0.37 mm(2), p = 0.493). Mean NIT of SES and EES were 0.11 ± 0.05 and 0.10 ± 0.05 mm, respectively (p = 0.367). Conversely, area, angle and depth of ESL in SES group were significantly greater than those in EES group (0.20 ± 0.39 vs. 0.03 ± 0.09 mm(2), p < 0.001, 56.2 ± 59.1° vs. 20.1 ± 41.9°, p < 0.001, 0.10 ± 0.09 vs. 0.03 ± 0.03 mm, p < 0.001). OCT showed that the efficacy of neointimal growth suppression is similar between SES and EES, whereas the adverse vascular response after EES implantation is smaller than that after SES implantation.

A pig-to-mouse coronary artery transplantation model for investigating the pathogenicity of anti-pig antibody.

BACKGROUND: Rejection of Gal-free (GTKO) donor pig cardiac xenografts is strongly associated with vascular non-Gal antibody binding, endothelial cell (EC) injury, and activation and microvascular thrombosis. We adopted a pig-to-SCID/beige small animal transplant model to compare the pathogenicity of baboon and human anti-pig antibody. METHODS: Wild-type (GT(+) ) or GTKO porcine coronary arteries (PCAs) were transplanted into the infrarenal aorta of SCID/beige mice. Three days after transplant, recipients were infused with anti-pig antibody (anti-SLA class I, an isotype control, naive or sensitized baboon serum, or naive human serum). PCAs were recovered 24 h after antibody infusion and examined using histology, immunohistochemistry, and in situ hybridization. RESULTS: Dose-dependent intragraft thrombosis occurred after infusion of anti-SLA I antibody (but not isotype control) in GT(+) and GTKO PCA recipients. Naive baboon serum induced thrombosis in GT(+) grafts. Thrombosis was significantly reduced by pre-treating naive baboon serum with Gal polymer and not observed when this serum was infused to GTKO PCA recipients. Naive human serum caused dose-dependent intragraft thrombosis of GTKO PCAs. In all cases, thrombosis involved graft-specific vascular antibody and complement deposition, macrophage adherence, EC delamination, and subendothelial thrombus formation. CONCLUSIONS: This study provides the first direct in vivo comparison of the pathogenicity of naive human and baboon serum. The results suggest that human preformed non-Gal antibody may have increased pathogenicity compared to baboon. This model, which showed a rejected graft histopathology similar to antibody-mediated rejection in cardiac xenotransplantation, may be useful to assess the pathogenicity of individual protein or carbohydrate specific non-Gal reactive antibodies.

Prevention of atrial fibrillation with ultra-low dose landiolol after off-pump coronary artery bypass grafting.

PURPOSE: Postoperative atrial fibrillation (AF) is a common complication of cardiac surgery that is associated with an increased incidence of other complications. The goal of this prospective randomized study was to evaluate the effect of ultra-low dose landiolol hydrochloride for prevention of AF after off-pump coronary artery bypass grafting (CABG). METHODS: The subjects were 47 patients who underwent isolated CABG and were randomly divided into those who received landiolol from ICU admission until the beginning of oral drug intake (Group L) and those administered diltiazem hydrochloride over the same period (Group D). The incidence of AF within one week after surgery was examined as the primary endpoint. Heart rate, blood pressure, cardiac output, and other hemodynamic parameters were used as secondary endpoints. The rates of adverse events were also recorded. RESULTS: The incidences of AF in the first postoperative week were 4.8% and 27% in Groups L and D, respectively (p = 0.046). There were no differences in hemodynamic parameters between the Groups. In multivariate analysis, no factor emerged as a significant risk factor for postoperative AF. Two patients had adverse events of asthma and hypotension, respectively, in Group L. CONCLUSION: Ultra-low dose landiolol is effective for preventing AF after CABG without worsening hemodynamics.

Proposal of a novel index for selection of optimal annuloplasty ring size for tricuspid annuloplication.

BACKGROUND: Optimal ring size in tricuspid annuloplasty (TAP) surgery to treat functional tricuspid regurgitation (TR) was investigated because optimal ring size remains undefined. METHODS AND RESULTS: Sixty seven patients who underwent TAP at our institution were retrospectively studied. Tricuspid Annuloplasty Ring size Index (TARI) was defined as implanted tricuspid annuloplasty ring size divided by body surface area (BSA). Different TARI cut-off values were tested to determine which value produced the greatest difference in TR improvement (TRI=preoperative minus postoperative TR grade) between patients with TARI smaller (group S) and larger (group L) than the cut-off. Group S was also subdivided by ring type: Cosgrove rings (SC) and MC3 rings (SM). TARI and TRI were negatively correlated (r=-0.307). A TARI threshold of 18.9 mm/m(2) produced the greatest and most significant difference (P<0.0005) in TRI. Defining groups S and L using this threshold, TRI was significantly greater for group S (1.77 ± 0.80) than for group L (0.97 ± 0.83); P <0.0005. There was no difference in TRI between groups SC and SM. CONCLUSIONS: A novel index TARI that normalizes tricuspid annuloplasty ring size by BSA was developed. Choosing ring size to make TARI <18.9 mm/m(2) is likely to be better than setting an upper limit of absolute ring size in the surgical treatment of TR.

New generation extracorporeal membrane oxygenation with MedTech Mag-Lev, a single-use, magnetically levitated, centrifugal blood pump: preclinical evaluation in calves.

We have evaluated the feasibility of a newly developed single-use, magnetically levitated centrifugal blood pump, MedTech Mag-Lev, in a 3-week extracorporeal membrane oxygenation (ECMO) study in calves against a Medtronic Bio-Pump BPX-80. A heparin- and silicone-coated polypropylene membrane oxygenator MERA NHP Excelung NSH-R was employed as an oxygenator. Six healthy male Holstein calves with body weights of about 100 kg were divided into two groups, four in the MedTech group and two in the Bio-Pump group. Under general anesthesia, the blood pump and oxygenator were inserted extracorporeally between the main pulmonary artery and the descending aorta via a fifth left thoracotomy. Postoperatively, both the pump and oxygen flow rates were controlled at 3 L/min. Heparin was continuously infused to maintain the activated clotting time at 200-240 s. All the MedTech ECMO calves completed the study duration. However, the Bio-Pump ECMO calves were terminated on postoperative days 7 and 10 because of severe hemolysis and thrombus formation. At the start of the MedTech ECMO, the pressure drop across the oxygenator was about 25 mm Hg with the pump operated at 2800 rpm and delivering 3 L/min flow. The PO2 of the oxygenator outlet was higher than 400 mm Hg with the PCO2 below 45 mm Hg. Hemolysis and thrombus were not seen in the MedTech ECMO circuits (plasma-free hemoglobin [PFH] < 5 mg/dL), while severe hemolysis (PFH > 20 mg/dL) and large thrombus were observed in the Bio-Pump ECMO circuits. Plasma leakage from the oxygenator did not occur in any ECMO circuits. Three-week cardiopulmonary support was performed successfully with the MedTech ECMO without circuit exchanges. The MedTech Mag-Lev could help extend the durability of ECMO circuits by the improved biocompatible performances.

Long-term results of modified Bentall procedure using flanged composite aortic prosthesis.

PURPOSE: We have been using the flanged composite aortic prosthesis and Carrel button technique to re-attach the coronary ostia in aortic root replacement procedures at our institution over the last twenty five years. Our objective was to evaluate the long-term results of aortic root replacement with this technique. METHODS: A total of 73 patients from January 1984 to August 2010 were included in this study. The median age was 52.7 ± 14.4 years (range 28-80 years). There were 48 male and 25 female patients. 44 patients (60.3%) had annuloaortic ectasia, and 15 patients (20.5%) had acute type A aortic dissection. Marfan syndrome was recognized in 12 patients (16.5%). RESULTS: The early mortality rate was 5.5% (n = 4). Causes of death were multiple organ failures in two patients and sepsis in another two patients. The actuarial survival rate was 84.2% at 5 years, 64.3% at 15 years and 51.9% at 25 years. Only one patient with aortitis needed a reoperation because of coronary pseudoaneurysm after 23 years from the previous operation. CONCLUSION: This modified Bentall procedure is reliable and safe, with superior long-term survival and a low rate of aortic reoperation.

[Surgical treatment for non-ischemic mitral regurgitation].

Non-ischemic mitral regurgitation( MR) is classified in degenerative MR, infective endocarditis( IE) and rheumatic MR. For degenerative MR, although 100% achievement of successful mitral valve plasty (MVP), it still important to evaluate mitral morphology preoperatively and to select suitable procedure.MR due to IE, the most important thing is to exclude vegetation completely. Then MVP is considered depends on its area of defect. Rheumatic MR is still difficult to accomplish MVP. Mitral valve replacement(MVR) is a main strategy for rheumatic MR.

Human CD55 expression blocks hyperacute rejection and restricts complement activation in Gal knockout cardiac xenografts.

BACKGROUND: Transgenic expression of human complement regulatory proteins reduces the frequency of hyperacute rejection (HAR) in Gal-positive cardiac xenotransplantation. In this study, we examined the impact of human CD55 (hCD55) expression on a Gal knockout (GTKO) background using pig-to-primate heterotopic cardiac xenotransplantation. METHODS: Cardiac xenotransplantation was performed with GTKO (group 1; n=6) and GTKO.hCD55 (group 2; n=5) donor pigs using similar immunosuppression. Cardiac biopsies were obtained 30 min after organ reperfusion. Rejection was characterized by histology and immunohistology. Intragraft gene expression, serum non-Gal antibody, and antibody recovered from rejected hearts were analyzed. RESULTS: HAR of a GTKO heart was observed. Remaining grafts developed delayed xenograft rejection. Median survival was 21 and 28 days for groups 1 and 2, respectively. Vascular antibody deposition was uniformly detected 30 min after organ reperfusion and at explant. A higher frequency of vascular C5b deposition was seen in GTKO organs at explant. Serum non-Gal antibody, antibody recovered from the graft, and intragraft gene expression were similar between the groups. CONCLUSION: HAR of GTKO hearts without hCD55 may occur. Expression of hCD55 seemed to restrict local complement activation but did not improve graft survival. Chronic vascular antibody deposition with evidence of protracted endothelial cell activation was seen. These observations suggest that non-Gal antibody-induced chronic endothelial cell activation coupled to possible hemostatic incompatibilities may be the primary stimulus for delayed xenograft rejection of GTKO hearts. To avoid possible HAR, future clinical studies should use donors expressing human complement regulatory proteins in the GTKO background.

[Surgical treatment for functional ischemic mitral regurgitation under beating heart].

Basic mechanism of ischemic mitral regurgitation (MR) is augmented leaflet tethering because of the out ward displacement of the papillary muscle by the left ventricular dilation. In 30% of ischemic MR, subvalvular procedure is necessary to eliminate MR. We propose subvalvular procedure aiming at a comprehensive remodeling of the entire mitral complex. This remodeling procedure consists of 3 major concepts; undersized mitral annuloplasty, division and reconstruction of secondary chords, and bilateral papillary muscle relocation. Subvalvular procedure under beating heart is effective to decide the length of artificial chord or papillary muscle relocation.

Pravastatin treatment before coronary artery bypass grafting for reduction of postoperative atrial fibrillation.

PURPOSE: The aim of this observational study was to determine the incidence of atrial fibrillation (AF) after coronary artery bypass grafting (CABG) in patients with or without preoperative pravastatin treatment. METHODS: Between January 2005 and December 2007, a total of 195 patients (39 women, mean age 66.5 +/- 10.2 years) who underwent CABG only were enrolled in this study. Patients were divided into three groups: nonstatin group (n = 111), atorvastatin group (n = 63), pravastatin group (n = 21). The endpoint of the study was the occurrence of new-onset AF during the first 14 days after CABG. RESULTS: Postoperative AF was less frequent in the pravastatin group (9.5%, 2/21 patients) than in the nonstatin group (34.2%, 38/111 patients; P = 0.0025) and the atorvastatin group (34.9%, 22/63 patients; P = 0.0257). C-reactive protein levels were lower in the pravastatin group 72 h after surgery (nonstatin vs. pravastatin, P = 0.0180; atorvastatin vs. pravastatin, P = 0.0383). The Kaplan-Meier analysis showed the protective effect of pravastatin against the risk of developing AF (nonstatin vs. pravastatin, P = 0.0369; atorvastatin vs. pravastatin, P = 0.0378). Multivariable analysis showed that pravastatin treatment conferred a reduced risk of AF (odds ratio 0.22, 95% confidence interval 0.05-0.92, P = 0.0172). CONCLUSION: Pravastatin treatment before CABG may decrease the incidence of postoperative AF.

[Heart positioners and proximal anastomotic devices in off-pump coronary artery bypass grafting].

Owing to development of device technology, off-pump coronary artery bypass grafting (OPCAB) has become a safe, reproducible and reliable procedure. Surgeons must understand the advantages and limitations of each device and select appropriate devices in individual case to avoid device-related complication and a waste of cost. The directions and pitfalls of heart positioners, stabilizers and proximal anastomotic devices were described. With the improved heart positioners and stabilizers all coronary targets have been well visualized and accessible, maintaining hemodynamic stability. Automated proximal anastomotic devices and proximal anastomotic assist devices have reduced the occurrence of cerebral complications compared with the side-clamp of the ascending aorta. The appropriate use of devices in OPCAB would be a promising and cost-effective procedure for revascularization of ischemic heart disease.

Efficient and durable gene transfer to transplanted heart using adeno-associated virus 9 vector.

BACKGROUND: In this investigation we studied the efficacy and durability of recombinant adeno-associated virus serotype 9 (rAAV9) vector-mediated gene transfer to the transplanted rat heart. METHODS: A rAAV9-CMV-lacZ vector diluted in cold (4 degrees C) University of Wisconsin solution was used to perfuse the rat coronary vasculature for 20 minutes prior to syngeneic heterotopic transplantation. Perfusion experiments (six groups, n = 3/group) were performed without rAAV9 and at four separate doses ranging from 2 x 10(9) to 2 x 10(12) viral genomes/ml. The transplanted heart was recovered 10 days or 3 months after transplantation and expression of lacZ assessed by histology, enzyme-linked immunoassay and real-time reverse transcript-polymerase chain reaction (RT-PCR). In a final group (n = 3), rAAV9 was administered systemically to compare the cardiac transduction efficiency and viral distribution to other organs. RESULTS: Transduction efficiency of perfused virus correlated with vector dose (p < 0.0001), with myocardial transduction ranging up to 71.74% at the highest dose. Cardiac expression of lacZ was equivalent at 10 days and 3 months. There was no evidence of viral gene transfer to other organs after heart transplantation. CONCLUSIONS: Our findings demonstrate efficient and durable rAAV9-mediated gene transfer to the transplanted heart after ex vivo perfusion and suggest that AAV9 is a promising vector for cardiac gene therapy.

Clinical study of the acute effects of intravenous nifekalant on the defibrillation threshold in patients with persistent and paroxysmal atrial fibrillation.

BACKGROUND: Antiarrhythmic agents are considered to have significant effects on the defibrillation energy requirement, so this study investigated the effects of nifekalant on defibrillation. METHODS AND RESULTS: Forty-two patients with persistent atrial fibrillation (AF) underwent electrical cardioversion via intracardiac electrode catheters prior to and after the intravenous administration of nifekalant. The success rate of the defibrillation and change in the defibrillation threshold using sequential incremental defibrillation energy deliveries was investigated. In addition, the parameters that could predict the beneficial effects of nifekalant were also assessed. Nifekalant significantly decreased the defibrillation energy requirement in 13 of the 42 cases, and nifekalant also converted AF to sinus rhythm with an identical energy to that of the last unsuccessful defibrillation in 21 of 42 cases. The success of defibrillation seemed to be dependent on significant prolongation of the intracardiac atrial electrogram intervals during AF by the nifekalant. CONCLUSIONS: Intravenous nifekalant significantly improved the electrical defibrillation efficacy in patients with persistent AF that was resistant to defibrillation, without any serious adverse effects.

Non-invasive radioiodine imaging for accurate quantitation of NIS reporter gene expression in transplanted hearts.

OBJECTIVE: We studied the concordance of transgene expression in the transplanted heart using bicistronic adenoviral vector coding for a transgene of interest (human carcinoembryonic antigen: hCEA - beta human chorionic gonadotropin: betahCG) and for a marker imaging transgene (human sodium iodide symporter: hNIS). METHODS: Inbred Lewis rats were used for syngeneic heterotopic cardiac transplantation. Donor rat hearts were perfused ex vivo for 30 min prior to transplantation with University of Wisconsin (UW) solution (n=3), with 10(9) pfu/ml of adenovirus expressing hNIS (Ad-NIS; n=6), hNIS-hCEA (Ad-NIS-CEA; n=6) and hNIS-betahCG (Ad-NIS-CG; n=6). On postoperative day (POD) 5, 10, 15 all animals underwent micro-single photon emission computed tomography/computed tomography (SPECT/CT) imaging of the donor hearts after tail vein injection of 1000 microCi (123)I and blood sample collection for hCEA and betahCG quantification. RESULTS: Significantly higher image intensity was noted in the hearts perfused with Ad-NIS (1.1+/-0.2; 0.9+/-0.07), Ad-NIS-CEA (1.2+/-0.3; 0.9+/-0.1) and Ad-NIS-CG (1.1+/-0.1; 0.9+/-0.1) compared to UW group (0.44+/-0.03; 0.47+/-0.06) on POD 5 and 10 (p<0.05). Serum levels of hCEA and betahCG increased in animals showing high cardiac (123)I uptake, but not in those with lower uptake. Above this threshold, image intensities correlated well with serum levels of hCEA and betahCG (R(2)=0.99 and R(2)=0.96, respectively). CONCLUSIONS: These data demonstrate that hNIS is an excellent reporter gene for the transplanted heart. The expression level of hNIS can be accurately and non-invasively monitored by serial radioisotopic SPECT imaging. High concordance has been demonstrated between imaging and soluble marker peptides at the maximum transgene expression on POD 5.

Recombinant adenoviral gene transfer does not affect cardiac allograft vasculopathy.

BACKGROUND: Adenovirus serotype 5 has remained the pre-eminent vector in pre-clinical gene therapy applications in cardiac transplantation. Concerns over the potential effects of adenoviral vectors on the later development of cardiac allograft vasculopathy (CAV) are addressed in this study. METHODS: Hearts (n = 22) harvested from Brown Norway rats were perfused ex vivo with either University of Wisconsin (UW) solution with no virus, Ad-CMV-LacZ or Ad-CMV-Null. Donor hearts were transplanted heterotopically into the abdomen of Lewis rats. All recipients received cyclosporine for the duration of the experiment. Transplanted hearts were recovered for analysis at 120 days. Sections of the heart were stained with elastic-van Gieson stain for morphometric analysis of the vessels to ascertain the degree of vascular luminal occlusion. Hematoxylin-eosin staining facilitated diagnosis of chronic rejection. RESULTS: Seventy-seven percent of transplanted hearts showed signs of chronic rejection with no difference in the proportion of animals between groups (p = 0.797). No difference was noted in the degree of vascular luminal occlusion between the Ad-Null (0.57 +/- 0.22), Ad-LacZ (0.62 +/- 0.19) and UW (0.47 +/- 0.29) groups (p = 0.653). CONCLUSIONS: Vascularized cardiac allografts transplanted from Brown Norway to Lewis rats demonstrated cardiac allograft vasculopathy CAV at 120 days. Adenoviral perfusion of the donor heart ex vivo did not affect the development of CAV.

The utility of right ventricular endomyocardial biopsy for the diagnosis of xenograft rejection after CD46 pig-to-baboon cardiac transplantation.

INTRODUCTION: Endomyocardial biopsy is the standard means of establishing cardiac allograft rejection diagnosis. The efficacy of this procedure in xenotransplantation has not been determined. In this study we compare the histology of right ventricular endomyocardial biopsy specimens with the corresponding full cross sections of explanted right ventricle (RV). We also compare RV with the related left ventricle (LV) cross sections. METHODS: Heterotopic CD46 pig-to-baboon cardiac xenotransplants (n = 64) were studied. RV endomyocardial biopsy specimens were taken at cardiac explant by using a standard bioptome (n = 24) or by sharp dissection (n = 40). Hematoxylin and eosin stained sections of RV and LV cross-section and RV endomyocardial biopsy specimens were compared in a blinded fashion. Characteristics of delayed xenograft rejection and a global assessment of ischemia were scored from 0 to 4 according to the percentage of myocardium involved (0, 0%; 1, 1%-25%; 2, 26%-50%; 3, 51%-75%; and 4, 76%-100%). RESULTS: Median graft survival was 30 days (range, 3-137 days). Linear regression analysis of histology scores demonstrated that specimens from both bioptome and sharp dissection equally represented the histology of the RV cross section. Global ischemic injury was strongly correlated between RV and RV endomyocardial biopsy (R(2) = 0.84) and between RV and LV cross sections (R(2) = 0.84). Individual characteristics of delayed xenograft rejection showed no significant variation between RV and RV endomyocardial biopsy or between RV and LV (p < 0.05). CONCLUSIONS: These results indicate that delayed xenograft rejection is a widespread process involving both right and left ventricles similarly. This study shows that histologic assessment of RV endomyocardial biopsy specimens is an effective method for the monitoring of delayed xenograft rejection after cardiac xenotransplantation.