Effect of Lactation on myocardial vulnerability to ischemic insult in rats / Efeito da Lactação sobre a Vulnerabilidade do Miocárdio ao Insulto Isquêmico em Ratas

Abstract Background: Cardiovascular diseases are the leading cause of mortality and long-term disability worldwide. Various studies have suggested a protective effect of lactation in reducing the risk of cardiovascular diseases. Objective: This study was designed to assess the effects of pregnancy and lactation on the vulnerability of the myocardium to an ischemic insult. Methods: Eighteen female rats were randomly divided into three groups: ischemia-reperfusion (IR), in which the hearts of virgin rats underwent IR (n = 6); lactating, in which the rats nursed their pups for 3 weeks and the maternal hearts were then submitted to IR (n = 6); and non-lactating, in which the pups were separated after birth and the maternal hearts were submitted to IR (n = 6). Outcome measures included heart rate (HR), left ventricular developed pressure (LVDP), rate pressure product (RPP), ratio of the infarct size to the area at risk (IS/AAR %), and ventricular arrhythmias - premature ventricular contraction (PVC) and ventricular tachycardia (VT). Results: The IS/AAR was markedly decreased in the lactating group when compared with the non-lactating group (13.2 ± 2.5 versus 39.7 ± 3.5, p < 0.001) and the IR group (13.2 ± 2.5 versus 34.0 ± 4.7, p < 0.05). The evaluation of IR-induced ventricular arrhythmias indicated that the number of compound PVCs during ischemia, and the number and duration of VTs during ischemia and in the first 5 minutes of reperfusion in the non-lactating group were significantly (p < 0.05) higher than those in the lactating and IR groups. Conclusion: Lactation induced early-onset cardioprotective effects, while rats that were not allowed to nurse their pups were more susceptible to myocardial IR injury.

Resumo Fundamento: As doenças cardiovasculares são a principal causa de mortalidade e invalidez a longo prazo a nível mundial. Diversos estudos têm sugerido um efeito protetor da lactação na redução do risco para doenças cardiovasculares. Objetivo: Este estudo foi desenvolvido para avaliar os efeitos da gestação e da lactação sobre a vulnerabilidade do miocárdio ao insulto isquêmico. Métodos: Dezoito ratas foram divididas aleatoriamente em três grupos: isquemia-reperfusão (IR), no qual os corações de ratas virgens foram submetidos à IR (n = 6); lactantes, no qual as ratas amamentaram seus filhotes por 3 semanas e os corações maternos foram, em seguida, submetidos à IR (n = 6); e não lactantes, no qual os filhotes foram separados após o nascimento e os corações maternos foram submetidos à IR (n = 6). As medidas de desfecho incluíram frequência cardíaca (FC), pressão desenvolvida no ventrículo esquerdo (PDVE), duplo produto (DP), razão do tamanho do infarto sobre a área sob risco (TI/ASR %) e arritmias ventriculares - contração ventricular prematura (CVP) e taquicardia ventricular (TV). Resultados: O TI/ASR foi substancialmente menor no grupo de lactantes quando comparado ao grupo de não lactantes (13,2 ± 2,5 versus 39,7 ± 3,5, p < 0,001) e ao grupo IR (13,2 ± 2,5 versus 34,0 ± 4,7, p < 0,05). A avaliação das arritmias ventriculares induzidas pela IR indicou que o número de CVPs compostas na isquemia, e o número e a duração das TVs na isquemia e nos primeiros 5 minutos de reperfusão no grupo de não lactantes foram significativamente (p < 0,05) mais elevados do que os encontrados nos grupos IR e de lactantes. Conclusão: A lactação induziu o aparecimento precoce de efeitos cardioprotetores, enquanto ratas que não foram permitidas a amamentar seus filhotes se mostraram mais suscetíveis à lesão miocárdica por IR.

Evaluation of success after second Ahmed glaucoma valve implantation.

Purpose: To evaluate the outcome of the second Ahmed glaucoma valve (AGV) surgery in eyes with failed previous AGV surgery. Design: Retrospective case series. Patients and Methods: Following chart review, 36 eyes of 34 patients with second AGV implantation were enrolled in this study. The primary outcome measure was surgical success defined in terms of intraocular pressure (IOP) control using two criteria: Success was defined as IOP ≤21 mmHg (criterion 1) and IOP ≤16 mmHg (criterion 2), with at least 20% reduction in IOP, either with no medication (complete success) or with no more than two medications (qualified success). Kaplan–Meier survival analysis was used to determine the probability of surgical success. Results: The average age of the patients was 32.7 years (range 4–65), and the mean duration of follow‑up was 21.4 months (range 6–96). Preoperatively, the mean IOP was 26.94 mmHg (standard deviation [SD] 7.03), and the patients were using 2.8 glaucoma medications on average (SD 0.9). The mean IOP decreased significantly to 13.28 mmHg (SD 3.59) at the last postoperative visit (P = 0.00) while the patients needed even fewer glaucoma medications on average (1.4 ± 1.1, P = 0.00). Surgical success of second glaucoma drainage devices (Kaplan–Meier analysis), according to criterion 1, at 6, 12, 18, and 42 months was 94%, 85%, 80%, and 53% respectively, and according to criterion 2, was 94%, 85%, 75%, and 45%, respectively. Conclusion: Repeated AGV implantation seems to be a safe modality of treatment with acceptable success rate in cases with failed previous AGV surgery.