Automatic measurement of short-term variability of repolarization to indicate ventricular arrhythmias in a porcine model of cardiac ischaemia

AIMS

An automated method for determination of short-term variability (STV) of repolarization on intracardiac electrograms (STV-ARIauto) has previously been developed for arrhythmic risk monitoring by cardiac implantable devices, and has proved effective in predicting ventricular arrhythmias (VA) and guiding preventive high-rate pacing (HRP) in a canine model. Current study aimed to assess (i) STV-ARIauto in relation to VA occurrence and secondarily (ii-a) to confirm the predictive capacity of STV from the QT interval and (ii-b) explore the effect of HRP on arrhythmic outcomes in a porcine model of acute myocardial infarction (MI).

METHODS AND RESULTS

Myocardial infarction was induced in 15 pigs. In 7/15 pigs, STV-QT was assessed at baseline, occlusion, 1 min before VA, and just before VA. Eight of the 15 pigs were additionally monitored with an electrogram catheter in the right ventricle, underwent echocardiography at baseline and reperfusion, and were randomized to paced or control group. Paced group received atrial pacing at 20 beats per min faster than sinus rhythm 1 min after occlusion. Short-term variability increased prior to VA in both STV modalities. The percentage change in STV from baseline to successive timepoints correlated well between STV-QT and STV-ARIauto. High-rate pacing did not improve arrhythmic outcomes and was accompanied by a stronger decrease in ejection fraction.

CONCLUSION

STV-ARIauto values increase before VA onset, alike STV-QT in a porcine model of MI, indicating imminent arrhythmias. This highlights the potential of automatic monitoring of arrhythmic risk by cardiac devices through STV-ARIauto and subsequently initiates preventive strategies. Continuous HRP during onset of acute MI did not improve arrhythmic outcomes.

Histological features with clinical impact in chronic allograft nephropathy: review of 66 cases

The histological features of chronic allograft nephropathy (CAN) are variable, since it is related to multiple donor and recipient factors. The main histological parameters in CAN are interstitial fibrosis, tubular atrophy, chronic vasculopathy and glomerulosclerosis. There have been many attempts to relate chronic deterioration of renal function with histologic features.

MATERIALS AND METHODS

We reviewed 66 kidney transplant patients (43 men/23 women) with renal failure 6 months after transplant. The clinical data included donor and recipient age, cold ischemia time, delayed graft function (DGF), creatinine clearance, proteinuria, HLA compatibility, CMV infection, cholesterol levels, diastolic and systolic blood pressure. Banff criteria were used to grade histological parameters. The relation between clinical and histological data were analyzed using chi square, Student t, Mann Whitney and Kruskal-Wallis tests as appropriate. The cumulative graft and patient survival rates were calculated by the Kaplan-Meier method.

RESULTS

The survival rate of patients with creatinine clearances >3 mg/dL at the time of the biopsy was worse than that of patients with creatinine <3 mg/dL (P =.001; log rank 20.1). We found an association between the grade of arteriosclerosis and the diastolic blood pressure (P =.017). The creatinine level was greater among patients with tabulitis than those without tubulitis (P =.06). In addition to our results we review the literature especially related to the histological feature of CAN in an attempt to detect histological findings predictive of the long term outcome of kidney allografts.