Catherine Sudarshan

Use of centrifugal left ventricular assist device as a bridge to candidacy in severe heart failure with secondary pulmonary hypertension

OBJECTIVES Raised pulmonary artery pressure (PAP), trans-pulmonary gradient (TPG) and pulmonary vascular resistance (PVR) are risk factors for poor outcomes after heart transplant in patients with secondary pulmonary hypertension (PH) and may contraindicate transplant. Unloading of the left ventricle with an implantable left ventricular assist device (LVAD) may reverse these pulmonary vascular changes. We studied the effect of implanting centrifugal LVADs in a cohort of patients with secondary PH as a bridge to candidacy. METHODS Pulmonary haemodynamics on patients implanted with centrifugal LVADs at a single unit between May 2005 and December 2010 were retrospectively reviewed. RESULTS Twenty-nine patients were implanted with centrifugal LVADs (eight HeartWare ventricular assist device (HVAD), HeartWare International, USA and 21 VentrAssist, Ventracor Ltd., Australia). Seventeen were ineligible for transplant by virtue of high TPG/PVR. All the patients were optimized with inotrope/balloon pump followed by LVAD insertion. Four required temporary right VAD support. Thirty-day mortality post-LVAD was 3.4% (1 of 29) with a 1-year survival of 85.7% (24 of 28). Thirteen patients have been transplanted to date: 30-day mortality was 7.7% (1 of 13) and 1-year survival was 91% (10 of 11). Baseline and post-VAD pulmonary haemodynamics were significantly improved: systolic PAP (mmHg), mean PAP, TPG (mmHg) of 57 ± 9.5, 42 ± 4.4 and 14 ± 3.9 reduced to 32 ± 7.5, 18 ± 5.5 and 9 ± 3.3, respectively. PVR reduced from 5 ± 1.5 to 2.1 ± 0.5 Wood units (P < 0.05). CONCLUSIONS In selected heart failure patients with secondary PH, use of centrifugal LVAD results in significant reductions in PAP, TPG and PVR, which are observed within 1 month, reaching a nadir by 3 months. Such patients bridged to candidacy have post-transplant survival comparable with those having a heart transplant as primary treatment.

Transcatheter aortic valve insertion: anaesthetic implications of emerging new technology

Transcatheter aortic valve insertion is a new development that potentially offers a number of advantages to patients and healthcare providers. These include the avoidance of sternotomy and cardiopulmonary bypass, and much faster discharge from hospital and return to functional status. The procedure itself however is quite complex, and presents significant demands in planning and implementation to the multidisciplinary team. Anaesthetic input is essential, and patient care in the perioperative period can be challenging. Early results have shown a significant mortality and morbidity rate, but the majority of procedures to date have been carried out in elderly patients with multiple comorbidities, making comparison with surgical aortic valve replacement inappropriate. Long-term outcomes are not yet known, but randomized controlled trials should allow this procedure and its application to be properly assessed.

Controlled reperfusion and pentoxifylline modulate reperfusion injury after single lung transplantation

OBJECTIVE Rodent models have suggested that initial low-pressure reperfusion of transplanted lungs reduces injury after ischemia. We investigated this phenomenon and the use of pentoxifylline in a porcine model of left single lung transplantation. METHODS Donor lungs were preserved with Euro-Collins solution for a mean ischemic time of 18.4 hours. Neutrophil trapping in the graft, pulmonary artery pressure, and gas exchange were assessed over a 12-hour period. Partial occlusion of the contralateral pulmonary artery allowed manipulation of the pulmonary artery pressure in the transplanted lung. Group A (n = 5) was perfused at a mean pulmonary artery pressure of 20 mm Hg, group B was reperfused at a mean pulmonary artery pressure of 45 mm Hg for 10 minutes before reducing the pressure to the same as group A, and group C was reperfused at a mean pressure of 20 mm Hg for 10 minutes, then increased to a mean of 45 mm Hg for the remainder of the experiment. Group D was reperfused as in group A with the addition of intravenous pentoxifylline. RESULTS Leukocyte sequestration was observed in the first 10 minutes after reperfusion in groups A, B, and C, with maximal sequestration at 2 minutes. Significantly more sequestration was observed in the first 6 minutes in group B than in groups A and C, which were similar. Pentoxifylline significantly reduced leukocyte sequestration. Pulmonary venous oxygen tension in the allograft lung was worst in group B. Groups A and C were similar, but group D was superior to all other groups (p < 0.001). CONCLUSIONS Low-pressure reperfusion, even when limited to the first 10 minutes, modulates reperfusion injury possibly through a leukocyte-dependent mechanism. The addition of pentoxifylline in the recipient confers significant additional benefit.

Comparison of Outcomes From Smoking and Nonsmoking Donors: Thirteen-Year Experience

BACKGROUND Lung transplantation remains the best treatment option for a variety of end-stage lung diseases. Pressure on the limited donor pool has led to the use of extended criteria donors. One aspect of this has been the liberalization of the use of smoking donors (SmD). METHODS This study is a retrospective review of lung transplants performed between April 1995 and August 2008 at a single institute. We examined the impact of donor smoking on short-term and long-term survival in relationship to recipient and donor demographics such as ischemic time, cytomegalovirus status, rates of rejection and infection, ventilation, and intensive care stay. Endpoints were survival, infection, and rejection. RESULTS During this 13-year period, 454 lung transplants were performed. Smoking history was available on 424 (93.4%) of these (SmD, n = 184; NSmD, n = 240). Seventy-one patients died within 3 months of transplant leaving 353 alive at 3 months posttransplant. Fatalities within the first 3 months were significantly higher in the SmD group (21% vs 13%, odds ratio 1.9, hazard ratio 3.3, p = 0.04). No significant difference in rejection and infection rates between recipients of lungs from SmD and NSmD at 3 months and at 1 year posttransplantation (p = 0.51 and 0.09) was found. Although recipients of lungs from SmD had higher odds of ventilation for more than 10 hours, the odds were only increased by 20%, which was not statistically significant. Recipients from SmD had significantly longer stays in the intensive care (odds ratio 1.9, p = 0.002). There was little evidence for an effect of SmD on the development of bronchiolitis obliterans. CONCLUSIONS In this large cohort of patients, donor smoking history has an effect on early survival but no effect on long-term survival. The cause of this early mortality is independent of infection and rejection. However, these data suggest that overall outcomes from the use of donor lungs from smokers are acceptable, particularly in the current era with limited donor organs.

Thoratec implantable ventricular assist device: The Papworth experience

OBJECTIVE The Thoratec (Thoratec Corp, Pleasanton, Calif) implantable ventricular assist device (IVAD) can be used for univentricular or biventricular support. The objective of this study is to review the 5-year experience of bridging patients to heart transplantation with this device in a single center. Surgical aspects, including hybrid pump pocket, double tunneling of driveline, and optimal cannulae placement, are discussed. METHODS This is a retrospective review of 24 patients treated between January 2002 and December 2007. Nineteen patients (79.1%) received a single implantable ventricular assist device as left ventricular assist devices, and 5 patients (21.9%) received 2 implantable ventricular assist devices as biventricular assist devices. The devices were implanted in pre-peritoneal/posterior rectus hybrid pump pockets. The driveline was passed through a 2-stage double-tunnel to exit onto the lateral chest wall. Patients were anticoagulated with Warfarin aiming for an international normalized ratio of 2.0 to 3.0. RESULTS Twenty male and 4 female patients with a mean age of 39.8 years (17-57 years) and a body surface area of 1.87 m(2) (1.63-2.2 m(2)) were supported for a total of 2308 patient-days. Mean duration of support was 96 days (10-301 days). The cause of heart failure was dilated cardiomyopathy in 18 patients and ischemic cardiomyopathy in 6 patients. Preoperatively, 23 patients were receiving inotropes, 12 patients required intra-aortic balloon pump support, 5 patients were intubated and mechanically ventilated, and 3 patients required continuous venovenous hemofiltration for renal support. Eleven patients (45.8%) were discharged with ventricular assist device support (1015 home patient-days). Complications observed were a) neurologic: stroke in 3 patients, transient ischemic attacks in 4 patients; and b) infection: driveline infection in 3 patients and pump pocket infection in 1 patient. There was no mechanical device failure. Support to transplantation was achieved in 17 patients (70.8%): 3 of 5 biventricular assist devices (60%) and 14 of 19 left ventricular assist devices (73.7%). CONCLUSION The Thoratec IVAD is a versatile and reliable ventricular assist device. It can provide univentricular or biventricular support for bridging patients to heart transplantation with acceptable complication rates. The portable Thoratec TLC-II console facilitated discharge while patients waited for a suitable donor heart.

Original articleGeneral thoracicComparison of Outcomes From Smoking and Nonsmoking Donors: Thirteen-Year Experience

BACKGROUND Lung transplantation remains the best treatment option for a variety of end-stage lung diseases. Pressure on the limited donor pool has led to the use of extended criteria donors. One aspect of this has been the liberalization of the use of smoking donors (SmD). METHODS This study is a retrospective review of lung transplants performed between April 1995 and August 2008 at a single institute. We examined the impact of donor smoking on short-term and long-term survival in relationship to recipient and donor demographics such as ischemic time, cytomegalovirus status, rates of rejection and infection, ventilation, and intensive care stay. Endpoints were survival, infection, and rejection. RESULTS During this 13-year period, 454 lung transplants were performed. Smoking history was available on 424 (93.4%) of these (SmD, n = 184; NSmD, n = 240). Seventy-one patients died within 3 months of transplant leaving 353 alive at 3 months posttransplant. Fatalities within the first 3 months were significantly higher in the SmD group (21% vs 13%, odds ratio 1.9, hazard ratio 3.3, p = 0.04). No significant difference in rejection and infection rates between recipients of lungs from SmD and NSmD at 3 months and at 1 year posttransplantation (p = 0.51 and 0.09) was found. Although recipients of lungs from SmD had higher odds of ventilation for more than 10 hours, the odds were only increased by 20%, which was not statistically significant. Recipients from SmD had significantly longer stays in the intensive care (odds ratio 1.9, p = 0.002). There was little evidence for an effect of SmD on the development of bronchiolitis obliterans. CONCLUSIONS In this large cohort of patients, donor smoking history has an effect on early survival but no effect on long-term survival. The cause of this early mortality is independent of infection and rejection. However, these data suggest that overall outcomes from the use of donor lungs from smokers are acceptable, particularly in the current era with limited donor organs.

A new porcine model of reperfusion injury after lung transplantation.

Rodent models have been described to investigate lung preservation and reperfusion injury but have significant disadvantages. In large animals single lung transplant studies are probably optimal but problems remain over the ability to rigorously separate the lungs for assessment while promoting medium to long-term animal survival for meaningful investigation. Our aim was to develop a novel and refined large animal model to assess reperfusion injury in the transplanted lung, overcoming the difficulties associated with existing models. Specifically, small animal models of lung transplantation usually have short perfusion times (often one hour) and include extracorporeal circuits while larger animal models often require the contralateral lung to be excluded after transplantation-an unphysiological situation under which to evaluate the graft. A porcine model of left lung allotransplantation was developed in which native and donor lungs are individually ventilated. Sampling catheters placed within the graft lung allowed specimen withdrawal without mixing of blood from the contralateral lung after reimplantation. The model permits a variety of clinical scenarios to be simulated with the native lung supporting the animal irrespective of function in the graft. This model has been used in over 60 transplant procedures with a postoperative survival time of 12 h being readily achieved. The mean operating time was 2.6 h. The mortality rate is 4% in our series. We have found the model to be reliable, reproducible and flexible. We propose this model as an adaptable investigation for evaluating lung reperfusion injury and preservation.

Size matching in lung transplantation: an evidence-based review.

The evidence base for size matching between donors and recipients in lung transplantation has not recently been reviewed in a comprehensive manner. Our aim in this study was to assimilate published studies that have addressed size matching of donors to recipients and to establish a pragmatic understanding of the range of lung sizes that may be used for lung transplantation. A comprehensive literature search was performed using Medline and PubMed up to and including September 2012, to identify scientific articles that relate to size matching between donors and lung transplant recipients. Seventy-two articles were identified, of which 21 had addressed the question of the impact of size mismatching on outcomes in lung transplantation. No study has specifically tested the consequences of intentionally mismatching above or below the hypothetical limits for double lung transplantation of a predicted total lung capacity for the donor of between 75% and 125% of the recipient predicted total lung capacity as set out in the ISHLT consensus report on lung donor acceptability criteria. Research is lacking that has robustly defined limits for size mismatch for single lung transplantation and for recipients with restrictive lung pathologies such as pulmonary fibrosis. Published research on the impact of size mismatching between lung transplant donors and recipients is limited by study design and size. It is centered on addressing the issue of mismatch in double lung transplantation in cohorts with a diagnostically heterogeneous make-up and in single lung transplant patients with chronic obstructive pulmonary disease.

Aortic arch homograft as a bypass conduit for superior vena cava obstruction

Superior vena cava (SVC) obstruction most commonly results from malignant disease of the superior mediastinum, which is amenable to percutaneous stenting. Superior vena cava syndrome can also be caused by transvenous pacemaker electrodes and indwelling venous catheters, when it may be refractory to minimally invasive treatment. We report 2 patients with superior vena cava obstruction treated successfully by a surgical bypass approach using cryopreserved aortic arch homografts.

Delayed Diagnosis of Q Fever: Finally Diagnosed After Elective Cardiac Surgery

Q fever is a bacterial infection caused by Coxiella burnetti. It can cause both acute and chronic illness. Chronic QF can present as a variety of clinical syndromes. A common and critical manifestation is endocarditis which can present atypically and is easily missed. This case describes a man who, after extensive investigation for splenomegaly and pancytopenia by several specialties, was finally diagnosed with Q fever endocarditis after unexpected aortic valve abnormalities found during elective cardiac surgery. Several factors contributed to diagnostic delay including aspects of clinical assessment and radiologic findings. Vigilance is essential for diagnosis and prompt initiation of effective treatment.