Noninvasive detection of fibrosis applying contrast-enhanced cardiac magnetic resonance in different forms of left ventricular hypertrophy relation to remodeling.

The epicardial coronary collateral vessels are visualized with coronary angiography, but this method does not provide significant information about the myocardial perfusion supplied with the collaterals. In this study, myocardial contrast echocardiography (MCE) was performed to assess the coronary collaterals in 29 patients with old myocardial infarction. MCE was performed by intracoronary injection of 2 ml agitated amidotrizoate sodium meglumine. The peak background-subtracted gray level (PGL) in the infarct area was determined from the digitized echocardiographic images obtained before and after injection into the noninfarct and donor artery. PGL was compared with the 3-point coronary angiographic grades of collaterals. PGL in the infarct area was significantly lower in patients with poor collaterals than in patients with moderate to good collaterals (5 +/- 4 vs 18 +/- 8 U mean +/- standard deviation, p less than 0.01). PGL in the infarct area was less than 10 U in the 3 patients with severe asynergy despite the moderate to good collateral supply, suggesting that activity of the collaterals was not good enough to preserve the wall motion effectively. It is concluded that (1) the degree of MCE enhancement in the infarct area generally corresponded to the collateral grades assessed with coronary angiography, and (2) MCE may provide a measure of the collateral perfusion.

Coronary collaterals assessed with myocardial contrast echocardiography in healed myocardial infarction.

Objective
Hypertrophic cardiomyopathy is underscored by profound phenotypic and genotypic heterogeneity. Echocardiographically, hypertrophic cardiomyopathy can be categorized into four morphological subtypes: reverse curve, sigmoidal, neutral contour, and apical variant. Previous studies indicate that reverse curve hypertrophic cardiomyopathy is the strongest predictor of a positive genetic test. Little is known about the spectrum and prevalence of mutations and genotype–phenotype correlations in apical hypertrophic cardiomyopathy.

Design
Between 1999 and 2007, 1053 patients with the diagnosis of hypertrophic cardiomyopathy (60% male, age at diagnosis 44.4 ± 19 years) underwent sarcomeric genetic testing. Blinded to the genetic test results, each echocardiogram was scored for septal morphology and phenotyping was performed using the patient's medical record. Subset analysis was performed to elucidate the genotype, phenotype, and outcome of apical hypertrophic cardiomyopathy.

Results
Overall, 71 patients (7%) had apical hypertrophic cardiomyopathy on echocardiography (63% male, mean age 47.8 ± 15 years, mean left ventricular wall thickness 19.8 ± 6 mm). Left ventricular outflow tract obstruction was uncommon (seven patients; 10%). Eighteen patients (25%) had a positive genetic test, with the majority of mutations found in MYBPC3 (six; 35%) and MYH7 (six; 35%). Follow-up was available on 68 patients (96%) with a median age of 57.3 years (range 19.3–82 years). Mean follow-up was 5.5 years (range 0.1–18.2 years). There was no statistical difference between the occurrence rates of adverse events between genotype-positive and genotype-negative groups.

Conclusions
In this largest cohort of patients with genetic testing for hypertrophic cardiomyopathy, <10% exhibited apical disease. This least common subtype was associated with a negative genetic test result 75% of the time. In contrast to prior publications suggesting a predilection for ACTC1/TPM1 mutations in patients with apical hypertrophic cardiomyopathy, the two most common genotypes (MYBPC3-HCM and MYH7-HCM) remained most common among patients who had a positive genetic test.

Genotype–Phenotype Correlations in Apical Variant Hypertrophic Cardiomyopathy

Hypertrophic cardiomyopathy is a common inherited cardiomyopathy, occurring in about 1 in 500 individuals.[1][1] The first gene mutation for this condition was identified in a large French Canadian family cohort in 1989.[2][2] Clinical presentation typically includes left ventricular hypertrophy in

/pdf/hypertrophic-cardiomyopathy-diagnosis-risk-stratification-a7zpq5pc04.pdf

Hypertrophic cardiomyopathy: diagnosis, risk stratification and treatment

Hypertrophic cardiomyopathy (HCM) is a primary and usually familial cardiac disorder with heterogeneous expression, unique pathophysiology, and a diverse clinical course. Clinically HCM requires a hypertrophied non-dilated left ventricle without evidence of any other cardiac or systemic disease that could produce the extent of hypertrophy observed. In the vast majority of individual adults dying from HCM, there is cardiomegaly typically in the range of twice the normal heart weight. The characteristic histological features in HCM are the presence of marked myocyte hypertrophy, myofiber disarray, left ventricular outflow tract plaque, intramural coronary abnormalities and interstitial fibrosis. The pathophysiology of HCM is complex and consists of multiple interrelated abnormalities, including left ventricular outflow tract obstruction, diastolic dysfunction, mitral regurgitation, myocardial ischemia, and arrhythmia. Sudden death is not an uncommon complication of HCM, and is often precipitated by exercise. The frequency of sudden death in HCM is up to 1 % per year in adults with 2–4 % per year in children and adolescents.

Pathology and Pathophysiology

HNCM tends to have more diffuse or generalized hypertrophy than HOCM, although these two types are not fundamentally different in aetiology (genetic). Extreme ASH is primarily related to a hereditary factor while HNCM, including apical hypertrophy, seems to be based on an abnormal disposition to produce myocardial hypertrophy in response to endogenous or exogenous stimulation such as catecholamines, chronic anoxia, hypertension or even aging. Hypertension by itself, however, can not be a cause of apical hypertrophy. The configuration of left ventricular hypertrophy in HCM can be divided roughly into several patterns: ASH, apical, postero-inferior, generalized or diffuse types, etc. ASH is not an essential morphology for HNCM. Apical hypertrophy is the only specific hypertrophic pattern which shows characteristic ECG abnormalities (giant negative T waves and high QRS voltage in left precordial leads). Inverted T waves combined with high QRS voltage tends to be a reflection of a localized hypertrophic portion in the left ventricular free wall. Abnormal Q waves associated with left axis deviation usually suggest marked septal hypertrophy. They seem to be related to conduction disturbances in myopathic septum.

Electrocardiographic, echocardiographic and ventriculographic characterization of hypertrophic non-obstructive cardiomyopathy

Biopsy specimens of 16 patients diagnosed by cardiac catheterization and angiography as having primary hypertrophic cardiomyopathy were examined. They were categorized as apical hypertrophy type in six, septal hypertrophy type in five, and others in five. Histological examinations disclosed edema, fibrosis, disorganization and bizarre nuclei in the myocardium in all types of disease entity, and it was possible to diagnose histologically primary cardiomyopathy in three each of the apical and other types. The remaining cases, however, did not show histological findings compatible with cardiomyopathy. We concluded that primary cardiomyopathy cannot always be diagnosed by biopsy data alone, and echocardiography and angiography are essential for its diagnosis.

Histological features of apical hypertrophic cardiomyopathy

Electrocardiographic features of apical hypertrophic cardiomyopathy are high QRS voltage and giant negative T waves greater than 10 mm in left precordial leads. We analyzed thirty patients with apical hypertrophic cardiomyopathy to clarify the correlation between left ventricular (LV) wall thickness and the depth of negative T waves. LV anterior wall thickness was measured by the left ventriculogram (LVG) in the RAO projection. LV posterior wall and septal thickness were measured by echocardiograms recorded from the left sternal border. THA and THM were defined as apical thickness and mid ventricular wall thickness, respectively. The results were as follows: LVG disclosed that the depth of negative T waves in apical hypertrophic cardiomyopathy was significantly related to the absolute thickness of apical segment itself rather than the difference in the distribution of thickness from the basal to apical segment of the left ventricle. This results support the clinical observation that giant negative T waves in some cases are associated with diffuse hypertrophy of the LV without a spade like configuration in LVG. Results of the echocardiographic analysis, however, revealed that the depth of negative T waves had no relation to the distribution of left ventricular hypertrophy. This is partly because of unsatisfied and difficult recordings and measurements of the true LV apical segment by echocardiography. The presence of both high QRS voltage and giant negative T waves is indispensable for the diagnosis of apical hypertrophy.

Correlation between left ventricular wall thickness and the depth of negative T waves in apical hypertrophic cardiomyopathy

The relationship of patterns of collateral pathways and the functions of collaterals in patients with proximal occlusion of the left anterior descending artery (LAD) was analyzed by coronary arteriography and left ventriculography. Forty-seven patients with dominant right coronary artery (RCA) as anatomic variations had nearly the same filling areas from three major collateral pathways from the RCA to the LAD via conus branches, marginal branches, and septal perforator. The grades of collateral flows were classified as good, fair and poor according to the sizes and numbers of collateral channels, and the filling density of contrast in each collateral and three (basal, mid and apical) segments of the main trunk of the LAD. On left ventriculography in the right anterior oblique projection, the anterior wall was divided into five segments, and the regional ejection fraction in each segment was measured from end-diastolic and end-systolic areas. Three main collateral pathways and connections to the LAD were observed from the RCA. Those were the conus branches to the basal-mid LAD, the marginal branches to the mid-apical LAD, and the posterior descending branches to the basal-mid LAD via the septal perforators. Only seven patients showed normal contraction in all of the segments (Group I). In seven patients with normal contraction in the basal-mid segments and reduced contraction in the apical segment of the anterior wall, the main collateral pathways from the RCA to the LAD were the posterior descending branches via the septal perforators (Group II). In 10 patients with reduced contraction in the basal-mid segments and normal contraction in the apical segment of the anterior wall, the main collateral pathways from the RCA were the conus branches and/or the marginal branches to the LAD (Group III). In the other 23 patients with reduced contraction in entire segments (Group IV), the patterns of segmental contraction were similar to those of either Group II or Group III. These findings indicate that in the majority of cases collateral circulation from the RCA did not preserve wall contraction in all segments perfused by the occluded LAD at rest, and suggest that various patterns of segmental contraction may be influenced by the dominant of collateral pathways.

[Coronary collaterals in patients with total obstruction of the proximal left anterior descending artery: their pathways and functional significance].

Between 1982 and 1983, we experienced four cases of hemodynamic collapse accompanied by an ST-segment depression in the ECG lead II, shortly after the cessation of cardiopulmonary bypass. The bypass graft flows monitored in these patients during the hemodynamic collapse episodes were remarkably low. In three cases, nitroglycerin (0.5–1 mg) was injected directly into the vein graft, which increased the graft flow suddenly, returned the ST-segment to the baseline, and improved the circulatory condition. Since 1984, however, diltiazem has been used in the cardioplegic solution and postoperative drip infusion. Due to the introduction of this drug, coronary artery spasm has not been seen in any of our patients since. These findings show that the monitoring of ST-segment changes and bypass graft flows are useful in the early diagnosis of coronary artery spasm after myocardial revascularization. Direct infusion of nitroglycerin into the vein graft is effective for the treatment of spasm, while diltiazem is useful in the prevention of coronary artery spasm incidental to myocardial revascularization.

Coronary artery spasm during coronary artery bypass surgery: its diagnosis, treatment and prevention.

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