Myocardial collagen type I and impaired left ventricular function under exercise in hypertrophic cardiomyopathy

BACKGROUND

Transaortic subvalvular myectomy (TSM) reduces left ventricular outflow tract gradient and improves symptoms and working capacity in patients with hypertrophic obstructive cardiomyopathy (HOCM). Nevertheless, TSM does not completely restore normal ventricular function, and some patients complain of symptoms despite optimal surgical results. Abnormal myocardial collagen structure in hypertrophic cardiomyopathy might be an indicator of impaired cardiac function.

METHODS

Nine patients with HOCM were investigated. Myocytic diameter, collagen volume fraction and light absorbance of immunohistochemically stained collagen subtype I and its product (Coll I(prod)) were measured quantitatively in myectomy specimens. Patients underwent symptom-limited bicycle exercise testing with equilibrium radionuclide angiocardiography to determine ejection fraction (EF). Right heart catheterization was performed simultaneously in order to measure pulmonary capillary wedge pressure (PCWP) as a parameter of global ventricular diastolic filling and cardiac index (CI) as a parameter of functional capacity.

RESULTS

Postoperatively, CI increased from 3.1 +/- 0.4 to 5.7 +/- 1.3 l/min/m(2) under exercise. EF was normal at rest (64 +/- 9 %) but did not increase significantly under exercise (66 +/- 14 %). Coll I(prod) (13.62 +/- 7.35 Vv%(prod)) correlated inversely with EF under exercise (r = -0.64; p = 0.05). PCWP increased under exercise from 8 +/- 2 mmHg at rest to 22 +/- 9 mmHg (p = 0.01). Coll I(prod) correlated with PCWP under exercise (r = 0.90; p = 0.001).

CONCLUSIONS

Increased collagen subtype I is a predictor of diastolic as well as systolic dysfunction under exercise in patients with HCM after successful TSM.

Repair of coronary arterioles after treatment with perindopril in hypertensive heart disease

In hypertensive heart disease, no data are available on the repair of coronary resistance vessels in patients after long-term ACE inhibitor treatment. Fourteen patients with essential hypertension were studied with coronary flow reserve and with transvenous endomyocardial biopsy before and after 12 months of antihypertensive treatment with perindopril (4 to 8 mg/d, mean 5.9+/-2.3 mg/d). Left ventricular muscle mass index decreased by 11% (from 145+/-41 to 128+/-36 g/m(2), P=0.04). Maximal coronary blood flow was increased by 54% (from 170+/-46 to 263+/-142 mL. min(-1). 100 g(-1), P=0.001), and minimal coronary vascular resistance was diminished by 33% (from 0.67+/-0.21 to 0.45+/-0.19 mm Hg. min. 100 g. mL(-1), P=0.001); consequently, coronary reserve increased by 67% from 2.1+/-0.6 to 3. 5+/-1.9 (P=0.001). Structural analysis revealed regression of periarteriolar collagen area by 54% (from 558+/-270 to 260+/-173 microm(2), P=0.04) and of total interstitial collagen volume density by 22% (from 5.5+/-3.8 Vv% to 4.3+/-3.2 Vv%, P=0.04), whereas arteriolar wall area was slightly but not significantly reduced. Long-term therapy with the ACE inhibitor perindopril induces structural repair of coronary arterioles that is mainly characterized by the regression of periarteriolar fibrosis and associated with a marked improvement in coronary reserve. These findings indicate the beneficial reparative effects of ACE inhibition on coronary microcirculation in hypertensive heart disease.

Endogenous plasma endothelin concentrations and coronary circulation in patients with mild dilated cardiomyopathy

OBJECTIVE

To determine whether increased plasma concentrations of endothelin-1 (ET-1) and big endothelin (BET) play a role in the regulation of coronary circulation in patients with idiopathic dilated cardiomyopathy (IDCM).

SETTING

Tertiary referral centre for cardiac diseases.

PATIENTS

Fourteen patients (eight male/six female; mean (SD) age 59 (9) years) with IDCM (ejection fraction 36 (9)%) and five normotensive subjects (two male/three female; age 52 (7) years) serving as controls were studied.

METHODS

Functional status was classified according to New York Heart Association (NYHA) class. Endogenous ET-1 and BET plasma concentrations from the aorta and the coronary sinus were determined by radioimmunoassay. Coronary blood flow, using the inert chromatographic argon method, myocardial oxygen consumption, and coronary sinus oxygen content under basal conditions were determined.

RESULTS

In the aorta, mean (SD) concentrations of ET-1 (IDCM 0.76 (0.25) v controls 0.31 (0.06) fmol/ml; p = 0.002) and BET (IDCM 3.58 (1.06) v controls 2.11 (0.58) fmol/ml; p = 0.014) were increased in patients with IDCM. Aortic ET-1 concentrations correlated positively with NYHA class (r = 0. 731; p < 0.001), myocardial oxygen consumption (r = 0.749; p < 0. 001), and coronary blood flow (r = 0.645; p = 0.003), but inversely with coronary sinus oxygen content (r = -0.633; p = 0.004), which was significantly decreased in IDCM patients (IDCM 4.68 (1.05) v controls 6.70 (1.06) vol%; p = 0.003).

CONCLUSIONS

The coronary circulation in patients with IDCM is exposed to an increased endothelin load. ET-1 concentrations correlate with functional deterioration. A decrease of the coronary sinus content of oxygen suggests a mismatch between coronary blood flow and metabolic demand. Thus, ET-1 might be a marker of a disequilibrium between myocardial oxygen demand and coronary blood flow in IDCM.

Immunohistochemical video-microdensitometry of myocardial collagen type I and type III

Collagen is an essential part of the cardiac interstitium. Collagen subtypes, their location, total amount and the architecture of the fibrillar network are of functional importance. Architecture in terms of density of the fibrillar network is assumed to be reflected by the intensity of immunohistochemical staining of collagen. The aim of this study was to evaluate a video-based microdensitometric method for quantifying density expressed as absorbance of collagen subtypes I and III stained with an indirect immunoperoxidase method in myectomy specimens of patients with hypertrophic obstructive cardiomyopathy. Various factors influencing the immunohistochemical staining product and the technical properties of the image analysis system were investigated. Linearity between collagen concentration and the absorbance of the immunohistochemical staining product was demonstrated for collagen I using a dot-blot technique. Immunohistochemical collagen staining and density measurement were easily reproducible. The cardiac disability of the patients was assessed according to the New York Heart Association (NYHA) criteria. There was a significant increase in collagen type I density with higher NYHA class, whereas no significant association was found for total collagen area fraction. Thus, video-based microdensitometry gives further insight into the structural remodelling of myocardial collagens and reveals their significance in the process of heart failure in hypertrophic cardiomyopathy.

Alterations of the architecture of subendocardial arterioles in patients with hypertrophic cardiomyopathy and impaired coronary vasodilator reserve: a possible cause for myocardial ischemia

OBJECTIVES

The study was designed to investigate the architecture of subendocardial arterioles of patients with hypertrophic cardiomyopathy (HCM) and angina pectoris with respect to coronary vasodilator reserve.

BACKGROUND

There is growing evidence that the coronary microvasculature is abnormal in HCM. Arterioles, which mainly regulate intramyocardial blood flow, are especially suspect.

METHODS

Thirteen patients with HCM (50.1+/-12.6 years old, mean value +/- SD) were studied after exclusion of any relevant coronary stenoses. Subendocardial arterioles (density [n/mm2], wall area [microm2], percent lumen area [%lumen], periarteriolar collagen area [microm2]), myocyte diameter (microm) and interstitial collagen fraction (Vv%) were evaluated by means of stereologic morphometry of transvenous biopsy samples. Coronary blood flow was measured quantitatively with the inert chromatographic argon method at basal conditions and after dipyridamole (0.5 mg/kg body weight over 4 min intravenously), and coronary vasodilator reserve was calculated as the ratio of coronary resistance at basal conditions and after pharmacologic vasodilation. Data from five normotensive subjects (45.4+/-11 years old, p = NS) served as control data.

RESULTS

Arteriolar density was diminished by 38% (p = 0.004) and %lumen by 13% (p = 0.009) in patients with HCM compared with control subjects. Coronary reserve was impaired in patients with HCM (2.28+/-0.6 vs. 5.34+/-1.49, p = 0.003) because of higher coronary resistance after vasodilation (0.48+/-0.14 vs. 0.22+/-0.06 mm Hg x min x 100 g/ml, p = 0.004). Coronary vasodilator reserve correlated with arteriolar density (r = +0.47, p = 0.045) and with %lumen (r = 0.65, p = 0.003).

CONCLUSIONS

In HCM, the architecture of preterminal subendocardial arterioles is altered by a reduced total cross-sectional lumen area, corresponding to an impaired coronary vasodilator capacity that may predispose to myocardial ischemia.

[Circulating adhesion molecules (cICAM-1, lcVCAM-1) in patients with suspected inflammatory heart muscle disease]

Some patients with non-ischemic heart failure show inflammatory changes in the myocardium which are thought to be of causal or pathogenetic relevance for the heart failure. The intercellular adhesion molecule-1 (ICAM-1) and the vascular adhesion molecule-1 (VCAM-1) are membrane proteins with receptor function from the immunoglobulin superfamily which mediate the vascular adhesion and transmigration of leucocytes into the tissue and undergo increased expression in chronic immunological-inflammatory processes. In addition to membrane-bound adhesion molecules, soluble forms can be detected in serum. In the present study we investigated the occurrence and the significance of circulating ICAM-1 and VCAM-1 in 71 patients with non-ischemic heart failure (47 M/24 F, mean age: 55 +/- 11 years).

METHODS

Serum concentrations of cICAM-1 and cVCAM-1 were analyzed using ELISA-Kits. The severity of heart failure was assessed in accordance to the NYHA-classification and to hemodynamic parameters (mean pulmonary pressure, left ventricular ejection fraction). Inflammatory heart disease was assessed histologically and immunohistologically (T-lymphocytes > 7.0/mm2, increased expression of the histocompatibility antigens of class I and II) in right ventricular endomyocardial biopsies. 16 healthy, age-matched patients (8 M/8 F, mean age: 55 +/- 6 years, mean ejection fraction 76 +/- 3%) without signs of inflammation in the myocardium (mean T-lymphocytes < 3.5 cells/mm2, low expression of HLA-class I and II) served as controls.

RESULTS

The mean serum concentrations of circulating ICAM-1 and VCAM-1 (cICAM-1, cVCAM-1) were higher in patients with non-ischemic heart failure (372 +/- 107 ng/ml and 949 +/- 439 ng/ml) than controls (264 +/- 37 and 710 +/- 164 ng/ml) (p < 0.05). The mean concentrations of both adhesion molecules varied as a function of the mean pulmonary pressure and the left ventricular ejection fracture (for cICAM-1: Pearson's r: 0.24 and -0.33, p < 0.05; for cVCAM-1: Pearson's r: 0.28 and -0.26, p < 0.05). In 38% (n = 16) of patients with elevated concentrations of cICAM-1 (> or = 337 ng/ml) and 41% (n = 7) of those with elevated serum levels of cVCAM-1 (> or = 1038 ng/ml), the myocardial biopsies showed increased lymphocytic infiltration between 7 and 22 T-lymphocytes/mm2 and an enhanced expression of the MHC antigens of class I/II as sign of an activated inflammatory process in the myocardium. All patients with more than 9.3 T-lymphocytes/mm2 in the myocardium (n = 7) had higher serum levels of cICAM-1 (447 +/- 146 ng/ml, p < 0.05 compared to controls) and of cVCAM-1 (1577 +/- 688 ng/ml, p < 0.001). Both adhesion molecules correlated significantly with the mean number of T-lymphocytes in the myocardium (Pearson's r: 0.31-0.37, p < 0.05).

SUMMARY AND CONCLUSION

The present study shows that the elevated levels of cICAM-1 and cVCAM-1 are often found in the serum of patients with non-ischemic heart failure. These raised serum levels correlate with inflammatory infiltrates in the myocardial tissue and with the clinical and hemodynamic signs of heart failure, thus, confirming a connection between heart failure and inflammatory changes in the myocardium.

Structural analysis of arteriolar and myocardial remodelling in the subendocardial region of patients with hypertensive heart disease and hypertrophic cardiomyopathy

Left ventricular hypertrophy is a risk factor for cardiovascular morbidity and mortality. In arterial hypertension and in hypertrophic cardiomyopathy it may be accompanied by clinical signs of myocardial ischaemia resulting from microcirculatory dysfunction in the absence of coronary macroangiopathy. Structural changes of the vascular and interstitial compartment of the heart are involved in the pathogenesis of impaired microcirculation. We investigated patients with hypertensive heart disease (HHD; n = 12) and hypertrophic cardiomyopathy (HCM; n = 19) without coronary macroangiopathy but with signs of myocardial ischaemia. Right septal endomyocardial biopsies were evaluated to quantify the structure of intramyocardial arterioles, collagen content and myocytic diameter by morphometric rules. Nine normotensive subjects served as controls. The groups differed significantly (P < 0.05) in myocytic diameter and total collagen content. The myocytic diameter correlated with the thickness of the interventricular septum. Arterioles in HHD showed a significant increase in cross-sectional medial area and in HHD patients the periarteriolar collagen area increased both in absolute terms and when standardized to medial area. Arteriolar density was significantly reduced in HCM. In a multivariate discriminant analysis the positive predictive value for differentiation of the groups by non-myocytic variables was 72.5% (P = 0.013). HHD and HCM differ in the structural alterations in the arteriolar bed. Medial hypertrophy and periarteriolar fibrosis prevail in HHD, and reduced arteriolar density is found in HCM. Different microvascular remodelling at the level of arterioles indicates distinct pathophysiologic processes that may contribute to the clinically observed disturbance of coronary microperfusion in these two diseases.

[Early postoperative changes in systolic and diastolic function at rest and during stress in patients with hypertrophic obstructive cardiomyopathy (HOCM) after myectomy]

INTRODUCTION

In this study systolic and diastolic function in patients with hypertrophic obstructive cardiomyopathy (HOCM) and intractable complaints to medication were investigated before and after a mean of 7 months after myectomy.

METHODS

Investigations in 19 patients with HOCM included echocardiography, Swan-Ganz-thermodilution-catheter and radionuclide-angiography.

RESULTS

Myectomy resulted in a reduction of the intraventricular gradient at rest (40.1 +/- 43.3 versus 7.6 +/- 12.0 mm Hg, p < or = 0.005) and under provocation (92.4 +/- 67.1 versus 21.3 +/- 26.5 mm Hg, p < or = 0.001). Echocardiographically determined basal septal thickness was reduced (24.9 +/- 6.3 versus 20.1 +/- 6.8 mm; p < or = 0.05) and diastolic diameter increased (40.4 +/- 5.2 versus 44.8 +/- 7.1; p < or = 0.05). Exercise tolerance increased from the maximally achieved 64.5 +/- 19.2 to 89.5 +/- 24.0 W (p < or = 0.001). Symptomatic status (NYHA) improved (1.7 +/- 1.4 versus 2.8 +/- 0.3 (p < or = 0.001). Systolic parameters showed at rest an increase in isovolumetric contraction time (65 +/- 39 versus 112 +/- 50 ms, p < or = 0.01), in time to peak ejection (109 +/- 40 versus 188 +/- 42 ms, p < or = 0.001), and a reduced left ventricular ejection fraction (72 +/- 12 versus 64 +/- 11%, p < or = 0.01). Analysis of regional ejection fraction revealed a significant reduction of ejection fraction in the basal septal region (p < or = 0.05). Increase of global and regional ejection fraction under exercise was still preserved. Mean pulmonary capillary wedge pressure was significantly reduced at rest (11.8 +/- 3.8 versus 8.6 +/- 2.4 mm Hg, p < or = 0.05) as well as under exercise (27.0 +/- 7.1 versus 20.4 +/- 6.8 mm Hg, p < or = 0.01), whereas left ventricular enddiastolic volume index (63 +/- 19 versus 72 +/- 17 ml*m-2, p < or = 0.05) was significantly increased.

CONCLUSIONS

In patients with HOCM, myectomy reduces intraventricular gradient, increases exercise capacity, and is accompanied by improved diastolic function parameters, while systolic function parameters are generally reduced.

Remodelling of intramyocardial arterioles and extracellular matrix in patients with arterial hypertension and impaired coronary reserve

The heart in pressure overload is threatened by the development of diastolic and systolic dysfunction even in the absence of coronary heart disease. In pressure overload, systolic wall stress leads to an increase in left ventricular mass through hypertrophy of myocytes. An activation of myocytic as well as non-myocytic cells is present. An increase in interstitial collagen accompanies hypertrophy of the myocytes. Thus, myocytic hypertrophy and fibrosis cause diastolic dysfunction early on, even when systolic function is still well preserved. In hypertensive heart disease, the coronary microcirculation is remodelled by thickening of the walls of intramyocardial arterioles in relation to their lumen and by an increase in periarteriolar fibrosis. This remodelling of the intramyocardial vasculature is combined with a reduction in coronary vasodilator reserve that may lead to malnutrition and malperfusion of the hypertrophied myocytes. The combined processes of myocytic hypertrophy, vascular remodelling and increased fibrosis may be important in the process of ventricular dilatation and failure in hypertensive heart disease.

Morphometric investigation of human myocardium in arterial hypertension and valvular aortic stenosis

Both arterial hypertension and aortic stenosis lead to pressure overload of the left ventricle. As intramyocardial vasculature is confronted with pressure overload in hypertension but not in aortic stenosis, structural differences are to be expected in both forms of left ventricular hypertrophy. With the aid of morphometry, we investigated human myocardium from autopsied hearts from six patients with arterial hypertension and 10 controls, as well as myectomy specimens from cardiac surgery from 14 patients with aortic stenosis. Mean left ventricular myocytic diameter was significantly (P less than 0.05) increased compared with controls (12.4 +/- 1.5 microns) during hypertension (+27%) as well as aortic stenosis (+65%) (P less than 0.05). This was combined with a greater volume density of perimyocytic fibrosis (controls = 0.8 +/- 0.4 V upsilon %) during hypertension (+250%) and aortic stenosis (+587%) (P less than 0.05). Walls of intramyocardial arterioles (external diameter 20-40 and 40-80 microns) were thickened to 32% and 44% (P less than 0.05) during hypertension, but not during aortic stenosis. Compared with controls, perivascular fibrosis of these arterioles was increased by +215% and 61% (P less than 0.05), respectively, during hypertension, but not during aortic stenosis.

CONCLUSIONS

Myocytic hypertrophy and increased perimyocytic fibrosis accompany intraventricular pressure overload (hypertension and aortic stenosis) in human hearts. Myocardial structure as a result of arterial hypertension, but not aortic stenosis, is also characterized by intramyocardial arteriole wall-thickening and increased perivascular fibrosis. Thus, distinct structural reaction patterns are noted in the cardiac hypertrophy associated with hypertension and aortic stenosis.