Effect of tandem lesions on haemodynamic parameters: an experimental study.

BACKGROUND: The morphology and extensity of the stenotic lesion is crucial as well as the obstruction ratio. It is well known that the complexity of lesions has a direct impact on endovascular treatment (PTCA/stent); however, the arrangement of the lesions is underestimated and not well studied. AIM: We sought to evaluate the haemodynamic effects of different stenotic lesion models and arrangements in vitro. METHODS: Vascular circulation was simulated in vitro. Oxygenator, tubing set, polytetrahidroflouroethylene synthetic graft, pressure and flow rate, sensors were used to build the simulation model. Measurements of isolated short, isolated long, identical stenotic tandem short, identical stenotic tandem long, sub-critical long, and critical short lesion combinations were performed and haemodynamic parameters were recorded. RESULTS: Tandem lesions were more likely to result in critical stenosis comparing single lesions with the same obstruction ratio. This difference became more significant as the obstruction ratio was raised. Tandem long lesions also resulted in more critical stenosis than tandem short lesions. It can be claimed that tandem lesions can result in more flow restriction with reference to single lesions with the same stenotic ratio. Contrary to expectations, tandem short lesions were found to be more stenotic compared with the same degree long individual lesions. CONCLUSIONS: It is effortless to give the decision for simple, discrete and individual lesions, while the ideal decision for long and complicated lesions may remain unclear. Even if these "grey zone" lesions are considered non-critical while investigating them one by one, it must be kept in mind that the overall stenotic effect of these lesions may lead to more haemodynamic impairment.

Pentamidine in Pneumocystis jirovecii prophylaxis in heart transplant recipients.

Despite advances in transplantation techniques and the quality of post-transplantation care, opportunistic infections remain an important cause of complications. Pneumocystis jirovecii (P. jirovecii) is an opportunistic organism, represents an important cause of infections in heart transplantation patients. Almost 2% to 10% of patients undergoing cardiac transplantation have Pneumocystis pneumonia. Prophylaxis is essential after surgery. Various prophylaxis regimes had been defined in past and have different advantages. Trimethoprim/sulfamethoxazole (TMP/SMX) has a key role in prophylaxis against P. jirovecii. Generally, although TMP/SMX is well tolerated, serious side effects have also been reported during its use. Pentamidine is an alternative prophylaxis agent when TMP/SMX cannot be tolerated by the patient. Structurally, pentamidine is an aromatic diamidine compound with antiprotozoal activity. Since it is not effectively absorbed from the gastrointestinal tract, it is frequently administered via the intravenous route. Pentamidine can alternatively be administered through inhalation at a monthly dose in heart transplant recipients. Although, the efficiency and safety of this drug is well studied in other types of solid organ transplantations, there are only few data about pentamidine usage in heart transplantation. We sought to evaluate evidence-based assessment of the use of pentamidine against P. jirovecii after heart transplantation.