Comparison of survival by vasoactive-inotropic score in patients receiving veno-arterial extracorporeal life support

After the initiation of veno-arterial extracorporeal membrane oxygenation (V-A ECMO) for hemodynamic support, patients often require vasopressor and inotropic medications to support their blood pressure and cardiac contractility. The vasoactive-inotropic score (VIS) is a standardized calculation of vasopressor and inotrope equivalence, which uses coefficients for each medication to calculate a total value. This study evaluated the association between the 30-day survival of patients receiving V-A ECMO support and the VIS calculated 24 h after ECMO cannulation (VIS24). This was a single-center, retrospective, observational cohort study. The median VIS24 of the entire cohort was 6.0, and was determined as a cutoff for comparison. Patients with a VIS24 < 6.0 were assigned to a group, and those with a VIS24 ≥ 6.0 were assigned to a second group. Patients with a VIS24 < 6.0 had higher 30-day survival than those with a VIS24 ≥ 6.0 (54.5% vs 41.4%; p = 0.03). The group with a VIS24 < 6.0 also had significantly improved survival to decannulation of ECMO support; however, there was no difference in the survival to hospital discharge. We conducted a secondary analysis of quartiles and determined that individuals with a VIS24 > 11.4 had the lowest survival in the cohort. This finding may help identify patients with the lowest probability of 30-day survival in those receiving V-A ECMO for hemodynamic support.

Optimizing anticoagulation for patients receiving Impella support

Anticoagulation of patients treated with the Impella percutaneous mechanical circulatory support (MCS) devices is complex and lacks consistency across centers, potentially increasing the risk of complications. In order to optimize safety and efficacy, an expert committee synthesized all available evidence evaluating anticoagulation for patients receiving Impella support in order to provide consensus recommendations for the management of anticoagulation with these devices. The evidence synthesis led to the creation of 42 recommendations to improve anticoagulation management related to the use of the Impella devices. Recommendations address purge solution management, intravenous anticoagulation, monitoring, evaluation and management of heparin-induced thrombocytopenia (HIT), and management during combination MCS support. The use of a heparinized, dextrose-containing purge solution is critical for optimal device function, and a bicarbonate-based purge solution may be an alternative in certain situations. Likewise, intravenous (ie, systemic) anticoagulation with heparin is often necessary, although evidence supporting the optimal assay and target range for monitoring the level of anticoagulation is generally lacking. Patients treated with an Impella MCS device may develop HIT, which is more difficult to evaluate and treat in this setting. Lastly, the use of Impella with extracorporeal membrane oxygenation or for biventricular support creates additional anticoagulation challenges.

Comparison of polyspecific versus IgG specific ELISA in predominately cardiac patients with suspected heparin induced thrombocytopenia

A diagnosis of heparin induced thrombocytopenia (HIT) must often be made based on clinical and laboratory evidence. This was a quasi-experimental study of patients admitted from June 2016 to October 2017. The primary endpoint was the incidence of false positive results in polyspecific and IgG specific enzyme-linked immunosorbent assay (ELISA); then we compared the sensitivity and specificity of each assays in predominately cardiac patients with suspected HIT. A sensitivity/specificity analysis was conducted using serotonin release assay (SRA) as the 'gold standard'. The secondary outcome measures included length of hospital stay. We identified a total of 155 patients who met the inclusion criteria. Confirmatory tests with SRA on both groups were completed; false positive result was higher in the polyspecific group when compared to the IgG group [60% vs. 5%]. The IgG specific ELISA test yielded a sensitivity of 100% and a specificity of 95% however, the polyspecific ELISA had a low yield for specificity of 24% but maintained 100% sensitivity. In the IgG specific group with HIT-, their median length of stay was halved compared to those who were HIT + ; hospital LOS in days, IQR [30 (27-81) vs. 15 (7-33) p = 0.023] and a shorter median LOS in the ICU, IQR [24 (5-47) vs. 6 (2-14); p = 0.079]. Hospital or ICU LOS was the same in both (HIT+ and HIT-) groups managed with polyspecific ELISA. The IgG specific test had few false positive results and a high sensitivity score. Ensuring appropriate testing can bring a substantial decrease in drug expenditure, reduced length of stay and prevent unnecessary anticoagulation.

Management of reproductive health after cardiac transplantation

Pregnancy after cardiac transplantation poses immense challenges. Maternal risks include hypertensive disorders of pregnancy, rejection, and failure of the cardiac allograft that may lead to death. Fetal risks include potential teratogenic effects of immunosuppression and prematurity. Because of the high-risk nature of pregnancy in a heart transplant patient, management of reproductive health after cardiac transplantation should include preconception counseling to all women in the reproductive age group before and after cardiac transplantation. Reliable contraception is vital as nearly half of the pregnancies in this population are unintended. Despite the associated risks, successful pregnancies after cardiac transplantation have been reported. A multidisciplinary approach proposed in this review is essential for successful outcomes. A checklist for providers to guide management is provided.

Bivalirudin for left ventricular assist device thrombosis

Pump thrombosis remains a serious complication of implantable ventricular assist device therapy and is associated with increased risk of morbidity and mortality. Optimal management strategies remain controversial and are guided largely by limited literature and expert opinion. Medical management of pump thrombosis, including the use of direct thrombin inhibitors, has been associated with mixed results. The purpose of this study is to report the outcomes associated with bivalirudin therapy in LVAD patients with suspected pump thrombosis. A single-center, retrospective observational study of 15 patients with suspected pump thrombosis that were all treated with bivalirudin therapy was conducted. The majority of subjects' initial treatment courses were unsuccessful [9/15 (60%)]; however, 6/15 (40%) achieved an initial improvement in serum lactate dehydrogenase (LDH) levels and were stabilized to be successfully discharged from the hospital. Of the subjects discharged, there was a high rate of recurrence of pump thrombosis within 6 months [5/6 (83.3%)]. Bivalirudin therapy was not associated with a consistent reduction in LDH among all subjects studied, and clinical responses to therapy appear to be associated with high rates of thrombosis recurrence. This study analyzes the largest cohort to date of LVAD patients with pump thrombosis treated with bivalirudin therapy, and suggests that alternative therapies should be considered in management.

Antiplatelet Therapy Bridging With Cangrelor in Patients With Coronary Stents: A Case Series

BACKGROUND

Cangrelor is an intravenous P2Y₁₂ receptor antagonist approved for use during percutaneous coronary intervention (PCI) to reduce ischemic events associated with new stent placement and has been used off-label at reduced doses guided by platelet function testing as a "bridge" from discontinuation of oral P2Y₁₂ receptor antagonists to surgical procedures when the long-term effects of oral agents are undesirable.

OBJECTIVE

To describe the dosing, laboratory monitoring, and clinical outcomes of a series of patients who received cangrelor as a "bridging" antiplatelet agent.

METHODS

This study is a retrospective analysis of all patients within the study center with coronary stents who received cangrelor as a bridge to surgical procedure and had VerifyNow monitoring during treatment.

RESULTS

A total of 11 patients were identified for inclusion. The median cangrelor dose was 0.5 µg/kg/min (interquartile range = 0.5-0.5) and was maintained in 7 of 11 patients. Doses ranged from 0.25 to 2 µg/kg/min during therapy, and 81.6% of VerifyNow results assessed were within goal range (⩽208 P2Y₁₂ reaction units). Bleeding complications during therapy occurred in 3 patients, all of whom were receiving concomitant heparin infusions, and no stent thrombosis was reported. Conclusion and Relevance: Low-dose cangrelor may represent an effective option for bridging antiplatelet therapy in patients with coronary stents. This study demonstrated that the majority of patients received adequate platelet inhibition without any incidence of stent thrombosis on 0.5 µg/kg/min using the VerifyNow assay to monitor platelet inhibition, which represents a lower dose than previously reported in the literature.

Clinical Factors Implicated in Primary Graft Dysfunction After Heart Transplantation: A Single-center Experience

BACKGROUND

Primary graft dysfunction (PGD) is a frequent complication after cardiac transplantation and remains one of the leading causes of mortality in these patients. The objective of this case-control study is to identify donor and surgical procedure's factors associated with PGD, and further guide possible strategies to prevent PGD.

METHODS

Retrospective analysis of the medical records of patients who underwent cardiac transplantation at Memorial Hermann Hospital at Texas Medical Center between October 2012 and February 2015.

RESULTS

The study population included 99 patients, of which 18 developed PGD. Univariate analysis of donor characteristics revealed opioid use (P = .049) and death owing to anoxia (P = .021) were associated with PGD. The recipient/donor blood type match AB/A was significantly associated with PGD (P = .031). Time from brain death to aortic cross clamp (TBDACC) of ≥3 and ≥5 days were also found to be associated with PGD (P = .0011 and .0003, respectively). Multivariate analysis confirmed that patients with a time from brain death to aortic cross clamp ≥3 and ≥5 days had lesser odds of developing PGD (odds ratio, 0.098 [P = .0026] and OR, 0.092 [P = .0017], respectively].

CONCLUSIONS

Our study showed that a longer time from brain death to aortic cross clamp was associated with lower odds of developing PGD. Therefore, postponing heart procurement for a few days after brain death seems to be beneficial in preventing PGD.

Treatment of Multiple Myeloma in a Heart Transplant Recipient

Malignancy following solid organ transplant remains a significant threat to the survival of cardiac transplant recipients. Plasma cell dyscrasias including multiple myeloma have been encountered in this population, and medication treatments traditionally used to treat these disorders demonstrate immunomodulatory effects that may have implications on the transplanted allograft. Lenalidomide is an immunomodulatory agent that has been used to treat plasma cell disorders, including light-chain amyloidosis (AL) and multiple myeloma, and represents such a class of medications in which the risks and benefits in the solid organ transplant population remain to be fully elucidated. This report highlights a clinical practice issue where the treatment of a patient's multiple myeloma with lenalidomide may have potentiated an episode of severe acute cellular rejection and further demonstrates the need for future investigation of the optimal treatment of plasma cell disorders including AL amyloidosis and multiple myeloma following solid organ transplantation.

A pseudo-outbreak of disseminated cryptococcal disease after orthotopic heart transplantation

Cryptococcal infection is the third most common invasive fungal infection (IFI) among solid-organ transplant (SOT) recipients and is considered an important opportunistic infection due to its significant morbidity and mortality. To determine whether a cluster of cryptococcosis in heart transplant patients was of nosocomial nature, three cases of orthotopic heart transplant recipients with postoperative disseminated cryptococcal infection were investigated and paired with an environmental survey in a tertiary care hospital. The infection prevention department conducted a multidisciplinary investigation, which did not demonstrate any evidence of health care-associated environmental exposure. Moreover, multilocus sequence typing showed that one isolate was unique and the two others, although identical, were not temporally related and belong to the most common type seen in the Southern US. Additionally, all three patients had preexisting abnormalities of the CT chest scan and various degrees of acute and chronic rejection. Reactivation was suggested in all three patients. Screening methods may be useful to identify at risk patients and trigger a prophylactic or preemptive approach. However, more data is needed.

Improved ticagrelor antiplatelet effect on discontinuation of phenytoin

OBJECTIVE

To report the influence of phenytoin on the antiplatelet effects of ticagrelor using a validated platelet aggregation study.

CASE SUMMARY

A 71-year-old man with coronary artery disease underwent percutaneous coronary intervention to revascularize several major coronary arteries. The patient was previously on phenytoin and was initiated on ticagrelor for antiplatelet therapy following stent placement. While the patient was receiving both drugs, platelet aggregation studies revealed less platelet inhibition than would be expected in a patient not taking a concomitant inducer of ticagrelor metabolism. On discontinuation of phenytoin, platelet inhibition improved.

DISCUSSION

Dual antiplatelet therapy with aspirin and a P2Y12 receptor antagonist following placement of coronary stents is critical to prevent stent thrombosis and subsequent myocardial infarction. Ticagrelor is a recently approved P2Y12 receptor antagonist that is subject to drug-drug interactions involving the hepatic cytochrome P450-3A4 enzyme system because of its metabolic elimination pathway. This case demonstrates ticagrelor's drug-drug interaction with phenytoin through a platelet aggregation study and supports the manufacturer recommendation to avoid the combination of ticagrelor with any known inducers of cytochrome P450-3A4 metabolism.

CONCLUSION

The combination of ticagrelor and phenytoin may represent a potentially clinically significant drug-drug interaction because of phenytoin induction of ticagrelor metabolism and reduced P2Y12 receptor inhibition in patients who have recently undergone percutaneous coronary intervention and cardiac stent placement.

The use of botulinum toxin type-B in the treatment of patients who have become unresponsive to botulinum toxin type-A -- initial experiences

The increasing use of botulinum toxin type-A, especially for focal dystonia and spasticity has highlighted the issue of secondary non-responsiveness. Within the last few years botulinum toxin type-B (Myobloc/Neurobloc) has become commercially available as an alternative to type-A. This paper discusses our initial experience of botulinum toxin type-B in a total of 63 individuals who attended our botulinum clinic. Thirty-six patients had cervical dystonia and a secondary non-response to type-A toxin. Thirteen of these patients (36%) had a reasonable clinical response to Neurobloc and continue to have injections. The other 23 patients either had no response, or a poor response, or had unacceptable side effects and ceased treatment. A small number of people with blepharospasm, hemifacial spasm and foot dystonia also had a disappointing response to injection. Twenty patients with spasticity were also type-A resistant. Seven of these show some continuing response to type-B, without unacceptable side effects. These findings demonstrate that botulinum toxin type-B has a place in the management of patients who have become non-responsive to type-A, but overall the responses to type-B toxin were disappointing.

Trans-splicing and polyadenylation of let-7 microRNA primary transcripts

Members of the microRNA (miRNA) class of 22-nucleotide RNAs regulate the expression of target genes that contain sequences of antisense complementarity. Maturation of miRNAs involves cleavage of longer primary transcripts, but little is yet understood about how miRNA genes are transcribed and enter the processing pathway. We find that relatively long, polyadenylated transcripts encoded by the Caenorhabditis elegans let-7 gene undergo trans-splicing to the spliced leader 1 (SL1) RNA. Deletions, including removal of the trans-splice site, upstream of mature let-7 sequence result in stable accumulation of primary transcripts and compromised production of mature let-7 RNA in vivo. Our data show that multiple steps of let-7 miRNA biogenesis can be uncoupled, allowing for complex regulation in the production of a functional miRNA. Finally, the observation that let-7 primary transcripts undergo splicing highlights the importance of identifying the sequence of endogenous pri-miRNA substrates recognized by the cellular processing machinery.

Interactions between red-billed oxpeckers, Buphagus erythrorhynchus, and domestic cattle, Bos taurus, in Zimbabwe

Many apparent interspecific mutualisms are poorly understood. Although theory has focused on the various evolutionary problems peculiar to mutualism, especially the need to identify mechanisms that protect a mutualism from cheating or exploitation, there are relatively few quantified examples of how organisms actually interact. Oxpeckers are believed to benefit their mammalian hosts by reducing tick loads, an assumption based on the fact that the birds include ticks in their diet. I watched red-billed oxpeckers foraging on domestic cattle in the Limpopo Valley between August 1996 and September 1997. From focal watches of 41 individually colour-ringed oxpeckers, I found that birds fed mainly on wounds, in ears and by 'scissoring' with the bill (a distinctive feeding technique). Observable tick feeding represented a very small percentage of their foraging time. Based on oxpecker behaviour at feeding sites, blood from open wounds appeared to be the favoured food: oxpeckers displaced each other significantly more, and were significantly less likely to be deterred by the cows' attempts to remove them, when feeding on a wound than at other feeding sites. The preference for blood, the inability of cows to prevent oxpeckers feeding on blood and the relatively small amount of visible tick feeding suggest that, certainly for cattle, oxpeckers may not be beneficial. However, as cows have not coevolved with oxpeckers, these results may not be representative of oxpecker relations with native African mammalian hosts. Copyright 1999 The Association for the Study of Animal Behaviour.