Role of left ventricular regional nonuniformity in hypertensive diastolic dysfunction

AbstractObjectives. This study investigated 1) the role of left ventricular diastolic nonuniformity in hypertensive left ventricular diastolic dysfunction, and 2) the effect of a calcium channel antagonist on diastolic nonuniformity in hypertensive and normotensive subjects.Background. Augmented left ventricular nonuniformity contributes to diastolic dysfunction in hypertrophic cardiomyopathy, Impaired left ventricular diastolic function with preserved systolic function has been recognized in hypertension. Therefore, abnormal ventricular regional nonuniformity might also be involved in hypertensive diastolic dysfunction in a milder form of hypertrophy.Methods. Thirteen patients with established hypertension underwent radionuclide ventriculography before and after nifedipine administration. Indexes of left ventricular function were derived by computer analysis of the time-activityy cure. After a compter subdivided the left ventricle into four regions, a timeactivity curve of each region was constructed to determine an index of left ventricular diastolic nonuniformity. This index was calculated as the sum of the absolute values of time difference between global and regional filling in the septal, the apical and the literal region. Tea normotensive subjects were studied for comparison, Echocardiography was performed in both group,Results. The two group were matched for age, gender, heart rate, echocardiographic dimensions and systolic function. In the hypertensive group, left ventricular diastolic filling index were impaired, with a negative correlation between peak filling rate and the diastolic nonuniformity index. Although the change in ejection fraction after nifedipine administration was similar in the two groups, the increase in filling rate was larger in the hypertensive patients. The diastolic nonuniformity index decreased after nifedipine in the hypertensive but not in the control group. This decrease correlated with improvad peak filling rate in the hypertensive group.Conclusions. In hypertensive with preserved systolic function, left ventricular diastoiic nonuniformity increases causing early diastolic dysfunction. Decreased diastolic nonuniformity after pharmacologic intervention contributes to lessened ventricular filling dysfunction, regardless of changes in conditions in hypertension. Thus, diastolic nonuniformity is an important determinant of left ventricular abnormality and be a target of pharmacologic intervention in hypertensive patients

Antihypertensive efficacy of olmesartan medoxomil and candesartan cilexetil in achieving 24-hour blood pressure reductions and ambulatory blood pressure goals

Background. For patients with hypertension, effective 24-hour blood pressure (BP) control is vital to ensure protection against the early morning surge in BP and the associated increased risk of cardiovascular events. The aim of this analysis was to assess the 24-hour antihypertensive efficacy of olmesartan medoxomil (20 mg once daily) compared with candesartan cilexetil (8 mg once daily), with particular emphasis on BP control during the early morning period. Methods. This is an additional analysis of a previously reported randomised, double-blind study in which 635 patients with mainly mild to moderate hypertension were randomised to 8 weeks of treatment with either olmesartan medoxomil 20 mg/day or candesartan cilexetil 8 mg/day. Changes from baseline during the last 4 and 2 hours of ambulatory BP measurement (ABPM) after 1, 2 and 8 weeks of treatment were compared between the two groups. In addition, the proportions of patients who achieved various ABPM goals, including those suggested by the European Society of Hypertension/European Society of Cardiology (ESH/ESC) [<125/80 mm Hg] and the Japanese Society of Hypertension (JSH) [<135/80 mm Hg], over 24 hours, during the daytime and at the last 4 and 2 hours of ABPM measurement were also compared. Results. After 8 weeks, significantly greater proportions of patients treated with olmesartan medoxomil 20 mg achieved 24-hour and daytime ABPM goals recommended by the guidelines of the ESH/ESC (25,6 % and 18,3 %, respectively) and JSH (37,5 % and 26,6 %, respectively) compared with candesartan cilexetil 8 mg (24-hour ESH/ESC goal 14,9 %, p<0,001; 24-hour JSH goal 26,6 %, p=0,003; daytime ESH/ESC goal 9,6 %, p=0,002; daytime JSH goal 16,4 %, p=0,002). During the last 4 hours of 24-hour ABPM, the proportions of patients who achieved the ESH/ESC and JSH ABPM goals were significantly greater with olmesartan medoxomil (33,3 % and 39,1 %, respectively) than with candesartan cilexetil (22,9 %, p<0,001 and 31,6 %, p=0,047, respectively). Similarly, during the last 2 hours of 24-hour ABPM, the proportions of patients who achieved these BP goals were either significantly greater (JSH) or approached statistical significance (ESH/ESC) with olmesartan medoxomil (26,9 % and 19,9 %, respectively), compared with candesartan cilexetil (19,6 %, p=0,028 and 14,3 %, p=0,061, respectively). Conclusion. Compared with candesartan cilexetil 8 mg, greater proportions of olmesartan medoxomil-treated patients (20 mg) achieved ESH/ESC and JSH ABPM goals over 24 hours. The superior BP control of olmesartan medoxomil was also reflected in the larger proportions of olmesartan medoxomil-treated patients who achieved the ESH/ESC and JSH ABPM goals during the early morning surge period. This not only demonstrates that olmesartan medoxomil 20 mg provides superior 24-hour BP reduction, but also suggests that olmesartan medoxomil may provide greater protection against the increased risk of cardiovascular events associated with the early morning BP surge period

Low energy synchronous transcatheter cardioversion of atrial flutter/fibrillation in the dog

AbstractThe feasibility and effectiveness of low energy synchronous transcatheter cardioversion of atrial flutter and fibrillation were examined in dogs with talc-induced pericarditis, A conventional electrode catheter was positioned transvenously in the right atrial appendage. Atrial flutter/ fibrillation was induced by using the train pulse method, and the tachyarrhythmia-inducing threshold was determined. The minimal effective cardioversion energy levels were compared in three different cardioversion methods: method A = delivery of shock between the proximal electrode (cathode) and the backplate (anode), method B = delivery between the proximal electrode (cathode) and the distal electrode (anode) and method C = conventional external cardioversion.In both methods A and B, all 149 cardioversion attempts were successful with shocks of ≤5 J. Shocks of ≤1 J resulted in successful cardioversion in 57 (70%) of 81 attempts, 50 (74%) of 68 attempts and 5 (12%) of 41 attempts with methods A, B and C, respectively. The mean minimal effective cardioversion energy levels were not significantly different between methods A and B (0.62 ± 0.67 versus 0.58 ± 0.71 J). Transcatheter cardioversion decreased the defibrillation threshold 3- to 75-fold (men 6-to 7-fold) from that of transthoracic cardioversion. The defibrillation threshold was not influenced by the inducibility of atrial flutter/fibrillation. There were no complications of heart block, ventricular fibrillation or pathologic evidence of severe shock-induced atrial injury.Thus, low energy synchronous transcatheter cardioversion of atrial flutter/fibrillation is considered feasible and effective. This technique may also be useful in managing the atrial flutter/fibrillation that can occur during electrophysiologic studies