Regional oxygen consumption persists in dyskinetic canine myocardium

The therapeutic advantage of combination antihypertensive drug therapy using amlodipine and irbesartan in hypertensive patients: Analysis of the post-marketing survey data from PARTNER (Practical combination therapy of Amlodin and angiotensin II Receptor blocker; safety and efficacy in patients with hypertension) study

Two-thirds of hypertensive patients need a combination antihypertensive therapy to achieve the target blood pressure (BP). The PARTNER (Practical combination therapy of Amlodin and angiotensin II Receptor blocker; Safety and efficacy in paTieNts with hypERtension) study is a prospective specific clinical use survey examining the efficacy and safety of 12-week treatment with amlodipine (AML) and Angiotensin II Receptor Blocker (ARB) in 5900 hypertensive patients. The current analysis was performed as to the BP control, adverse reactions, and the effects on laboratory data in patients treated with the combination of AML and irbesartan (IRB), namely the patients added AML to already taking IRB (AML add-on group, n = 1202) and the patients added IRB to AML (IRB add-on group, n = 1050). Both study groups showed distinct decreases in office BP at 4 week (p < 0.001) and the antihypertensive effects were sustained to 12 week (p < 0.001). The percentage of patients achieving BP < 140/90 mmHg was ∼70% in either group. Proteinuria and estimated glomerular filtration rate (eGFR) were significantly improved in hypertensive patients with baseline eGFR <60 ml/min/1.73 m(2). Serum uric acid was reduced either by adding AML or IRB, and the reductions were prominent in patients with serum uric acid >7 mg/dl. The incidence of adverse reactions was as few as 1.11% and there were no severe adverse reactions which hampered the continuation of combination therapy. In conclusion, combination antihypertensive therapy with AML and IRB effectively lowers BP without particular safety problems, reduces serum uric acid especially in patients with hyperuricemia and exhibits renoprotective effects in patients with chronic kidney disease.

The effect of amlodipine alone and in combination with atenolol on bowel habit in patients with hypertension: an observation

The prevalence of hypertension increases with advancing age. The management of hypertension especially in the elderly has its own limitations. Verapamil is not recommended in the elderly on account of high incidences of troublesome constipation. Amlodipine has become very popular with the cardiologists and general physicians. Survey of literature has not yielded any citation where the troublesome effect of amlodipine on the gastrointestinal tract has been reported. In an experimental study on isolated rabbit intestine we have demonstrated that amlodipine dose-dependently inhibit the spontaneous activity of the intestinal tract. With this background the present observational study was planned. A total of 100 hypertensive patients were included in the present study. Fifty patients were on amlodipine alone and 50 patients on combination of amlodipine and atenolol. The main parameter analyzed was the frequency and consistency of stool before and after intake of drug. The relative risk (RR) of developing constipation was 4.00 with 95% CI 0.8930 to 17.917 in amlodipine alone group. From this study it can be concluded that the relative risk of developing constipation is 4 times more in patients who are taking amlodipine alone as compared to those patients who are on combination of amlodipine and atenolol.

Regression of Left Ventricular Mass by Antihypertensive Treatment

Blood pressure–lowering therapy reduces left ventricular mass, but the question of whether differences exist among drug classes has not been fully resolved. Our aim was to compare the effects of diuretics, β-blockers, calcium channel blockers, angiotensin-converting enzyme inhibitors, and angiotensin receptor blockers on left ventricular mass regression in patients with hypertension on the basis of prospective, randomized comparative studies. We performed meta-analyses, involving pooled pairwise comparisons of the drug classes and of each class versus other classes statistically combined, and meta-regression analyses to identify the determinants of the regression. The 75 relevant publications involved 84 pairwise comparisons and 6001 patients. Regression of left ventricular mass was significantly less ( P =0.01) with β-blockers (9.8%) than with angiotensin receptor blockers (12.5%), but none of the other analyzable pairwise comparisons between drug classes revealed significant differences ( P >0.10). In addition, β-blockers showed less regression than the other 4 classes statistically combined ( P <0.01), and regression was more pronounced with angiotensin receptor blockers versus the others ( P <0.01). In multivariable meta-regression analysis on all of the treatment arms, β-blocker treatment was a significant and negative predictor of the regression (−3.6%; P <0.01), but this was not the case for the other drug classes, including angiotensin receptor blockers. In conclusion, β-blockers show less regression of left ventricular mass, whereas angiotensin receptor blockers may induce larger regression. The inferiority of β-blockers appears to be more convincing than the superiority of angiotensin receptor blockers.

Characteristic dysfunction of stunned myocardium induced by 2,3-butanedione monoxime without ischaemia

1. In the present study, we tested the hypothesis that, even in the absence of prior ischaemia, 2,3-butanedione monoxime (BDM), an inhibitor of contraction at the actin-myosin level, could produce the postischaemic dysfunction characteristic of stunned myocardium. 2,3-Butanedione monoxime was injected directly into the left anterior descending coronary artery (LAD) before and again after myocardial stunning produced by 15 min occlusion of the LAD followed by 30 min reperfusion. 2. Regional myocardial force, segment shortening and regional work were measured in both the LAD-perfused area and the area perfused by the circumflex coronary artery, which served as a control area. Regional dysfunction produced by BDM injection or ischaemia-reperfusion was assessed quantitatively by five parameters: end-diastolic length (EDL), shortening onset delay (delay), systolic bulge (bulge), end-shortening time delay (EST) and tail work ratio (TWR). 3. It was found that injection of BDM into the LAD caused dyskinesis similar to that caused by occlusion-reperfusion. Both displayed elevated EDL and marked increases in delay, bulge, EST and TWR; these parameters were significantly higher in the dyskinesis caused by BDM injection. Despite dysfunctional fibre shortening, intracoronary BDM injection did not reduce regional force. 4. Thus, BDM can elicit changes similar to those characteristic of postischaemic dysfunction. Because contractility was not impaired, dysfunction was apparently caused by disrupting the association between contractile force and muscle motion.

Interaction between left ventricular wall motion and intraventricular flow propagation in acute and chronic ischemia

Myocardial ischemia has been associated with left ventricular (LV) postsystolic shortening. The combination of tissue Doppler imaging and high frame-rate acquisition of two-dimensional color flow makes it possible to study the interaction between LV wall motion and intraventricular flow propagation. The aim of this study was to examine in a clinical model the impact that acute myocardial ischemia and prior myocardial infarct might have on LV flow patterns and to explain the underlying mechanisms from the tissue Doppler data. LV flow propagation and tissue velocities during early diastole were studied in 18 healthy individuals, 17 patients with prior anterior myocardial infarct, and 16 patients before and during percutaneous coronary intervention (PCI) of the left anterior descending artery. Normal individuals had intraventricular flow propagation toward the apex during isovolumic relaxation. During this early diastolic time phase, myocardial velocities measured at mid- and apical septal segment were directed away from the apex. Before PCI, patients without myocardial infarction had similar findings as in normal individuals. In contrast, each patient with either prior myocardial infarction or PCI-induced acute ischemia had flow propagation opposite to normal individuals, and tissue velocities reversed toward the apex during early diastole. Reversal of early diastolic LV flow propagation in acute and chronic anterior myocardial ischemia reflects postsystolic shortening in the dyskinetic apical and septal myocardial segments.

Myocardial hibernation: a delicate balance

The pathophysiology of myocardial hibernation is characterized as a situation of reduced regional contractile function distal to a coronary artery stenosis that recovers after removal of the coronary stenosis. A subacute "downregulation" of contractile function in response to reduced regional myocardial blood flow exists, which normalizes regional energy and substrate metabolism but does not persist for more than 12-24 h. Chronic hibernation develops in response to one or more episodes of myocardial ischemia-reperfusion, possibly progressing from repetitive stunning with normal blood flow to hibernation with reduced blood flow. An upregulation of a protective gene program is seen in hibernating myocardium, putting it into the context of preconditioning. The morphology of hibernating myocardium is characterized by both adaptive and degenerative features.

Early Target Organ Damage and Its Reversibility: The Heart

Left ventricular hypertrophy (LVH) represents not only an adaptation to increased load, but also a risk factor and a marker of risk of cardiovascular diseases. It may be detected early in the development of the disease by electrocardiography or echocardiography. LVH is often associated to abnormalities of systolic and diastolic function, and its presence clearly predisposes not only to cardiac ischemia and to congestive heart failure, but also to a higher incidence of stroke. A large number of clinical and experimental studies have shown that long-term antihypertensive treatment may be associated with regression of LVH. Long-term antihypertensive treatment is associated with a progressive decrease of LV mass. Differences on reduction of LV mass using different classes of antihypertensive drugs for the same decrease of blood pressure are usually mild, although the effect on cardiac structure and tissue composition are probably not the same. In fact, not only the quantity of left ventricular mass, but also its quality (i.e., collagen content, contractile machinery) should be evaluated and improved by treatment. The incidence of cardiovascular events in hypertensive patients is clearly related to the value of LV mass achieved during treatment; in fact, a reduction in LVH by antihypertensive treatment is associated with improvement in outcome and with decrease of the risk of cardiovascular morbidity and mortality, even independently from changes of other risk factors, including blood pressure. In patients with LVH at baseline, the decrease of LV mass is associated with a number of pathophysiological changes such as 1) improved systolic performance at the midwall, 2) possible improvement of diastolic filling, 3) autonomic nervous system changes toward normalization, 4) possible reduction or ventricular arrhythmias and 5) coronary reserve improvement. All these changes might explain an improvement of clinical prognosis in hypertensive patients. Ongoing studies will more precisely assess the quantitative relation between development or regression of LV mass, improvement of systolic and diastolic function and incidence of cardiovascular events. At present time detection, prevention and reversal of LVH represent a major goal in the management of hypertensive patients.

Regional differences of myocardial infarct development and ischemic preconditioning

The spatial and temporal development of myocardial infarction depends on the area at risk (AAR), the severity and duration of blood flow reduction (energy supply) as well as on heart rate and regional wall function (energy demand). Both supply and demand can vary within the AAR of a given heart, potentially resulting in differences in infarct development. We therefore retrospectively analyzed infarct size (IS, %AAR, TTC) in 24 anesthetized pigs in vivo following 90 min hypoperfusion and 120 min reperfusion of the LAD coronary artery, which supplies parts of the LV septum (LVS) and anterior free wall (LVAFW). The total LAD perfusion territory averaged 49.8 +/- 14.2 (SD) g (49.2 +/- 8.4% of LV); 61.4 +/- 8.1% of the AAR was LVAFW. IS within the LVS was 25.3 +/- 15.1%, while IS within the LVAFW was 16.6 +/-10.1% (p<0.05). While ischemic blood flow (radiolabeled microspheres) did not differ between LVS (0.05 +/- 0.02 ml/min/g) and LVAFW (0.05 +/- 0.03 ml/min/g), perivascular connective tissue (56 +/- 9 vs. 38+/-7 microm(2), p < 0.05) and the capillary-to-myocyte distance (1.65 +/- 0.23 vs. 1.18 +/- 0.23 mm, p < 0.05) were larger in LVS than in LVAFW. Interestingly, IS in LVS (9.3 +/- 9.6%, n = 24) and LVAFW (9.2 +/- 9.1%) were reduced to the same absolute extent by ischemic preconditioning with one cycle of 10 min ischemia and 15 min reperfusion, suggesting that a similar regional difference exists also in the protection afforded by ischemic preconditioning. The mechanism(s) for that remain(s) to be established.

CONCLUSION

In pigs, regional differences in infarct development and protection from it exist in the LAD perfusion territory, which are independent of ischemic blood flow but apparently related to pre-existing structural differences.

Amlodipine improves vascular function in patients with moderate to severe hypertension

The long-term effects of amlodipine, a calcium channel blocker, were examined in patients with moderate to severe hypertension. Eighteen never-treated patients with moderate to severe essential hypertension (49 +/- 8 years) were studied. In all patients, forearm blood flow (FBF) was measured by plethysmography before and 6 months after amlodipine treatment. Endothelium-nondependent and endothelium-dependent vasodilations were assessed by intrabrachial infusion of sodium nitroprusside (SNP) and acetylcholine (ACh), respectively. FBF modification by vitamin C, an oxygen radical scavenger, was also assessed under ACh infusion. The results were compared with those of 13 normal subjects. Blood pressure was significantly lowered (from 176 +/- 17/97 +/- 13 to 144 +/- 12/82 +/- 10 mm Hg) after treatment (P < 0.01). Forearm vascular resistance was increased in the hypertensive patients before treatment; however, it was normalized after treatment during SNP infusion and was improved during ACh infusion. Since vitamin C improved FBF under ACh infusion both before and after the amlodipine treatment, it is suggested that the production of free radicals was not canceled by amlodipine. The analysis of heart rate variability showed that amlodipine does not activate sympathetic nerve function. Therefore, amlodipine is effective in lowering blood pressure associated with the improvement of vascular function, and is suggested to be an effective antihypertensive agent for patients with moderate to severe hypertension.

Change in diastolic left ventricular filling after one year of antihypertensive treatment: The Losartan Intervention For Endpoint Reduction in Hypertension (LIFE) Study

BACKGROUND

It is well established that hypertensive patients with left ventricular (LV) hypertrophy have impaired diastolic filling. However, the impact of antihypertensive treatment and LV mass reduction on LV diastolic filling remains unclear.

METHODS AND RESULTS

Echocardiograms were recorded in 728 hypertensive patients with ECG-verified LV hypertrophy (Cornell voltage-duration or Sokolow-Lyon) at baseline and after 1 year of blinded treatment with either losartan or atenolol-based regimen. Systolic and diastolic blood pressures (BP) were reduced on average 23/11 mm Hg; isovolumic relaxation time and E/A ratio became more normal, and LV inflow deceleration time prolonged (all P<0.001). Directionally opposite changes in isovolumic relaxation time (IVRT) and deceleration time indicate improvement in active LV relaxation and passive chamber stiffness during early diastole. Prevalences of normal LV filling increased, abnormal relaxation and pseudonormalization decreased, and restrictive filling pattern remained unchanged (P<0.05). Patients with reduction in LV mass had smaller left atrial diameter, shortened IVRT, increased E/A ratio, and prolonged LV inflow deceleration time (all P<0.001). Patients without LV mass reduction had no change in diastolic filling parameters (P=NS). IVRT shortening was independently associated with reduction in LV mass. Increase in E/A ratio was independently associated with reduction in diastolic BP, and increase in the deceleration time was independently associated with reduced end-systolic relative wall thickness.

CONCLUSIONS

Antihypertensive therapy resulting in LV mass or relative wall thickness regression is associated with significant improvement of diastolic filling parameters related to active relaxation and passive chamber stiffness compared with patients without regression, independent of BP reduction; however, abnormalities of diastolic LV filling remain common.

Time course of the effects of temocapril on cardiovascular structure and function in patients with essential hypertension

To investigate the time course of cardiovascular structural changes in patients with essential hypertension after angiotensin-converting enzyme (ACE) inhibition, we determined left ventricular structure, minimal vascular resistance in the forearm as an index of resistance vessel structure and stiffness beta of carotid artery in 15 essential hypertensive subjects during a placebo period and after 2, 6, and 12 months of temocapril treatment. Blood pressure decreased within 2 weeks, and the antihypertensive effects were noted throughout the 12-month administration period. Left ventricular mass index decreased significantly after 2 months (120+/-12 to 106+/-9 g/m2; p < 0.01) and was normalized after 12 months (88+/-6 g/m2). Postischemic minimal vascular resistance in the forearm decreased gradually from 2.1+/-0.5 to 1.6+/-0.4 PRU at month 12 of temocapril treatment. In contrast, increased stiffness index beta of carotid artery was not altered during a 1-year treatment period (11.4+/-4.9 to 11.6+/-3.8 at month 12 of treatment). These data indicated that the regression of structural changes of left ventricle and arterioles occurred gradually and progressively for 1-year treatment with ACE inhibition, but large arteries were not affected.

Cardiovascular structural alterations in hypertension: effect of treatment

Available data support the hypothesis that antihypertensive drugs may determine a significant regression of cardiac and vascular structural changes. Antihypertensive drugs that inhibit the renin-angiotensin or, to a lesser extent, the adrenergic system may more consistently and promptly reduce left ventricular hypertrophy (LVH) and vascular structural changes. It is possible that all antihypertensive agents, when used for long enough periods, will reduce LV mass, whereas only certain drugs will reduce mass within a period of few months, so that any difference among classes of antihypertensive drugs is more quantitative than absolute. However, a rapid reversal of LVH may be particularly important because reducing blood pressure in the presence of an elevated LV mass may be associated with impairment of coronary perfusion. Structural changes of small resistance arteries play a significant role in the genesis of increased vascular resistance in hypertension and in the maintainance of high blood pressure values. Studies in humans have demonstrated that minimal vascular resistance can be reduced with the use of different antihypertensive drugs, while a complete normalization of the media: lumen ratio was observed only with ACE inhibitors. Further studies are needed to assess the true clinical impact, in terms of reduced morbidity and mortality of reversal of cardiovascular structural changes in hypertensive patients. However, available studies indicate that reversal of LVH reduces the pathological consequences of increased left ventricular mass, and preliminary data suggest that complete regression of LVH may be associated to a decreased risk for cardiovascular events.