Pathophysiology of chest pain in patients with cardiomyopathies and normal coronary arteries

Exercise-induced ST-segment depression and systolic dysfunction in patients with nonobstructive hypertrophic cardiomyopathy

BACKGROUND

ST-segment depression is common in patients with hypertrophic cardiomyopathy (HCM). However, it is not clear whether exercise-induced ST-segment depression in patients with HCM and patent coronary arteries is associated with changes in left ventricular function.

METHODS

Left ventricular function was continuously evaluated in 53 patients with nonobstructive HCM during supine ergometer exercise with a radionuclide ventricular function monitor equipped with a cadmium telluride detector. On the basis of the ST-segment changes during exercise, the patients were divided into 2 groups: group N had no ST-segment depression, and group D had >/=0.1 mV ST-segment depression.

RESULTS

Exercise duration, blood pressure, heart rate, and rate-pressure product during exercise did not differ between the 2 groups. End-diastolic volume at rest and at peak exercise did not differ between groups D and N. In contrast, the end-systolic volume in group N decreased during exercise, whereas in group D it increased. As a result, the left ventricular ejection fraction in group D decreased from 70% +/- 7% to 59% +/- 15% (P <.0001), whereas ejection fraction in group N increased from 65% +/- 8% to 71% +/- 11% (P =.0002). There was a strong correlation between exercise-induced ST-segment depression and changes in ejection fraction from rest to peak exercise (P <.0001).

CONCLUSIONS

These results suggest that the exercise-induced ST-segment depression seen in patients with nonobstructive HCM is associated with systolic dysfunction during exercise.

The effect of coronary vasospasm on the direction of ST-segment deviation in patients with both hypertrophic cardiomyopathy and vasospastic angina

BACKGROUND

There has been no report of ECG changes during anginal attacks in patients with coexistent hypertrophic cardiomyopathy (HCM) and vasospastic angina.

STUDY OBJECTIVES

To elucidate the change in ST-segment during anginal attacks in patients with coexistent HCM and vasospastic angina (the HCM group) in comparison with that of patients with vasospastic angina and no left ventricular hypertrophy (the non-HCM group).

DESIGN

Retrospective study.

PATIENTS

Twelve patients in the HCM group, and 28 patients in the non-HCM group.

MEASUREMENTS

The direction of ST segment shift, either ST-segment elevation or depression, on the ECGs recorded during vasospastic anginal attacks with severe vasoconstriction in the epicardial coronary artery after intracoronary injection of acetylcholine.

RESULTS

Age, male gender, and distribution of coronary arteries in which the vasospasm occurred were similar between the two groups. Collateral circulation to the affected arteries was absent in all the study patients. The prevalence of anginal attacks associated with ST-segment elevation was 2.7 times higher in the non-HCM group than in the HCM group (51. 5% [17 of 33 attacks] vs 18.8% [3 of 16 attacks], respectively; p = 0.03).

CONCLUSIONS

In the HCM group, myocardial ischemia associated with a transmural injury pattern seen on the ECG, which is represented as ST-segment elevation, seldom develops during vasospastic anginal attacks because of marked left ventricular hypertrophy.

Intracoronary enalaprilat improves metabolic coronary vasodilation in patients with idiopathic dilated cardiomyopathy

Coronary flow reserve is reduced in patients with idiopathic dilated cardiomyopathy (DCM). We examined acute effects of intracoronary enalaprilat on metabolic coronary vasodilation during pacing tachycardia in patients. Coronary blood flow (Doppler guidewire) and diameter (quantitative angiography) were measured in seven patients with DCM and seven control subjects. In the DCM group, tachypacing increased coronary blood flow by 37 +/- 22% from the baseline before enalaprilat and by 65 +/- 22% (p < 0.01 vs. before treatment) after enalaprilat (0.5 microg/kg/min for 5 min, i.c.) at comparable double product. Pacing-induced dilation of the epicardial coronary artery also was greater after enalaprilat (p < 0.05). Effects of enalaprilat on coronary blood flow and diameter during pacing tachycardia were abolished by pretreatment with intracoronary administration of the nitric oxide (NO) synthesis inhibitor, N(G)-monomethyl-L-arginine. These beneficial effects of enalaprilat on large and small coronary vasodilation were not observed in control patients. Thus, intracoronary enalaprilat acutely augmented dilator responses of the large and small coronary arteries to pacing tachycardia in patients with DCM, and NO appeared to play an important role in mediating the effects of enalaprilat. These favorable effects of enalaprilat on the coronary circulation may be of clinical significance in patients with heart failure due to nonischemic DCM. Further long-term studies of the effects of angiotensin-converting enzyme inhibition on coronary vasodilation will be needed in this population.

Augmented basal nitric oxide production contributes to maintenance of coronary blood flow in dogs with pacing-induced heart failure

It remains controversial whether basal nitric oxide (NO) production in coronary resistance vessels in heart failure is enhanced or not. A transonic Doppler flow probe was placed around the left anterior descending coronary artery, and complete atrioventricular block was produced in fifteen dogs. The coronary pressure-flow relationships during long diastole were analyzed without and with pacing-induced heart failure. Three weeks after pacing at 240/min, plasma norepinephrine and renin activity significantly rose. Right atrial pressure and left ventricular end-diastolic pressure increased, and cardiac output and coronary perfusion pressure decreased; however, mean coronary blood flow did not change after pacing (55 +/- 5 to 52 +/- 5 ml/min/100 g, mean +/- SEM). The slope of the diastolic coronary pressure-flow relationship became steeper (1.22 +/- 0.13 to 1.62 +/- 0.09 ml/min/100 g/mmHg, p < 0.05) with a slight increase in the measured zero-flow pressure (29.5 +/- 1.1 to 32.8 +/- 1.5 mmHg, p < 0.05) after pacing. After pretreatment with indomethacin, administration of NG-nitro-L-arginine methyl ester caused an equal increase in the zero-flow pressure before (31.4 +/- 1.7 to 39.2 +/- 2.2 mmHg, p < 0.05) and after heart failure (33.9 +/- 2.5 to 41.6 +/- 2.2 mmHg, p < 0.05), and more decline of the slope of the coronary pressure-flow relationship in heart failure (1.86 +/- 0.22 to 1.20 +/- 0.05 ml/min/100 g/mmHg, p < 0.05) than before heart failure (1.11 +/- 0.12 to 1.05 +/- 0.11 ml/min/100 g/mmHg, N.S.). This indicates that in failing hearts the vasodilatory action of NO in small vessels predominates despite the presence of several vasoconstricting factors. These results suggest that coronary blood flow is maintained despite detrimental hemodynamic and activated neurohumoral factors in the initial stage of heart failure, and that increased basal NO production plays a central role in the maintenance of basal coronary blood flow.

Differential coronary microvascular function in patients with left ventricular dysfunction of unknown cause--implication for possible mechanism of myocardial ischemia in early stage of cardiomyopathy

To evaluate whether or not coronary microvascular dysfunction is associated with exercise-induced myocardial ischemia in left ventricular dysfunction of unknown cause, both the treadmill exercise test (TET) and coronary hemodynamics were studied in 20 patients with impaired left ventricular ejection fraction (<50% by radionuclide ventriculogram), normal cardiac size, normal coronary angiogram and no evidence of clinical heart failure. Ten subjects with atypical chest pain were studied as the control. Coronary hemodynamics were studied both at baseline and after dipyridamole infusion (0.56mg/kg, i.v. for 4'). There was no difference in age, gender, blood pressure, baseline great cardiac venous flow (GCVF) and coronary vascular resistance between ten patients with a positive TET and the other ten with a negative TET. At baseline, coronary sinus oxygen concentration was increased and myocardial oxygen consumption reduced in patients with a positive TET compared with those with negative a TET. After dipyridamole infusion, maximum GCVF (102+/-47 vs. 144+/-31 ml/min, P=0.027) and coronary flow reserve (2.31+/-0.49 vs. 3.00+/-0.61, P=0.012) were significantly reduced and minimum coronary vascular resistance was higher (1.00+/-0.42 vs. 0.63+/-0.12 mmHg/ml/min, P=0.016) in patients with a positive TET than in those with a negative TET. At follow-up, 40% of patients with a positive TET and 10% of those with a negative TET developed clinical heart failure with a dilated left ventricle during a period of 45 months. Thus, coronary microvascular function is heterogeneous in patients with left ventricular dysfunction of unknown cause. In some of them, coronary microvascular dysfunction could be related to the presence of exercise-induced myocardial ischemia, suggesting that similar pathophysiology underlies the early stage of dilated cardiomyopathy and syndrome X.

Abnormal coronary flow profiles at rest and during rapid atrial pacing in patients with hypertrophic cardiomyopathy

To examine the mechanism of myocardial ischemia in hypertrophic cardiomyopathy (HCM), coronary flow velocity was measured in the left anterior descending coronary artery (LAD) using a Doppler guide wire in 11 patients with HCM and in 8 normal controls. The average peak velocity (APV), percent increase of APV (%APV), and APV during systole (Vs) and diastole (Vd) were calculated at rest and during rapid atrial pacing. The APV in HCM reached a peak value at a heart rate of 90 beats/min, while in the controls the APV increased continuously until the heart rate reached 130 beats/min [%APV (130 beats/min); 103+/-30% in HCM vs 139+/-23% in controls, p<0.04]. During rapid atrial pacing, Vs in the controls increased, whereas Vs in HCM decreased further. During high-rate pacing, Vd in HCM reached a peak value at a heart rate of 90 beats/min, whereas in the controls, Vd increased continuously until the heart rate reached 130 beats/min. The acceleration rate of early diastolic flow was significantly lower in HCM than in the controls (1.85+/-0.66 vs 3.18+/-1.62 m/s2, p<0.03). This abnormal response might be due to an increase in the reverse systolic flow and a decrease in the diastolic flow, probably caused by a slow acceleration of early diastolic flow velocity in the LAD.

Coronary microvascular disease in humans

Myocardial perfusion abnormalities occur in the absence of epicardial coronary artery disease in patients with a wide spectrum of cardiovascular disorders including microvascular angina, hypertension and left ventricular hypertrophy, coronary atherosclerosis, hypercholesterolemia, and non-ischemic left ventricular dysfunction. These patients have limited coronary microvascular dilator reserve which occasionally is associated with evidence of myocardial ischemia. Primary microvascular hyperconstriction (spasm) is also proposed to cause myocardial ischemia in a subset of patients with rest angina. There is ample evidence suggesting that endothelial dysfunction contributes to microvascular dysfunction, but the precise mechanism of endothelial dysfunction is not known. Nitric oxide is one of the key molecules which control microvascular tone and therefore coronary blood flow, and its decreased availability appears to be involved under certain conditions. This hypothesis has attracted considerable interest as a new therapeutic strategy for these patients having coronary microvascular derangements caused by divergent cardiovascular diseases.

Coronary vasodilator reserve is impaired in patients with hypertrophic cardiomyopathy and left ventricular dysfunction

BACKGROUND

We tested the hypothesis that a reduced delivery of blood to the myocardium is involved in the development of systolic dysfunction of patients with hypertrophic cardiomyopathy (HCM).

METHODS AND RESULTS

Eighty-four patients with HCM (62 men, age 43 +/- 12 years) were studied. Left ventricular dimensions and function (fractional shortening) were evaluated by 2-dimensional echocardiography. Myocardial blood flow (MBF) was measured by N13 -ammonia or O15 -water and positron emission tomography at baseline and after dipyridamole; coronary vasodilator reserve (CVR) was calculated as dipyridamole/baseline MBF. Patients with HCM in advanced New York Heart Association (NYHA) classes had lower dipyridamole MBF (NYHA class I = 1.57 +/- 0.64 vs class II = 1.52 +/- 0.58 vs class III = 0.96 +/- 0.32 mL/min per gram; analysis of variance, P <.05) and CVR (NYHA class I = 1.93 +/- 0.64 vs class II = 1.69 +/- 0.54 vs class III = 1.40 +/- 0.43; analysis of variance, P <.05). A positive linear correlation between fractional shortening and dipyridamole MBF was demonstrated (R = 0.23, P <.05), and patients with abnormal fractional shortening had lower dipyridamole MBF (1.07 +/- 0.43 vs 1.58 +/- 0.62 mL/min per gram, P <.01).

CONCLUSIONS

Systolic dysfunction in HCM may be caused by a more severe alteration of the coronary vasodilator capacity.

Clinical characteristics in Japanese patients with coexistent hypertrophic cardiomyopathy and coronary vasospasm

There are only a few reports concerning coexistent hypertrophic cardiomyopathy (HCM) and vasospastic angina. Clinical characteristics in patients with both diseases have not been clarified yet. This study was designed to elucidate the relationship between chest pain and coronary vasospasm in HCM patients and to delineate clinical characteristics in patients with both HCM and coronary vasospasm. First, 36 patients with HCM underwent acetylcholine provocation test for coronary vasospasm and were divided into two groups on the basis of presence or absence of coronary vasospasm. Next, the following risk factors for coronary artery disease were compared between the two groups: hypertension, smoking, hyperlipidemia, diabetes mellitus, and hyperuricemia. Coronary vasospasm was induced in 10 (28%) of 36 patients with HCM. There were no significant differences in age and male gender between the two groups. Smoking was more prominent in HCM patients with than without coronary vasospasm (80% vs 35%, p<0.05), but there were no differences in the prevalence of other risk factors between the two groups. In conclusion, coronary vasospasm appears to play a significant role in the etiology of myocardial ischemia in Japanese patients with HCM, and smoking might be a major risk factor for coexistence of HCM and coronary vasospasm.

A follow up study of myocardial involvement in patients with mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes (MELAS)

OBJECTIVE

To investigate cardiac function in patients with mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes (MELAS) and clarify the clinical features of cardiomyopathy in MELAS.

PATIENTS

11 consecutive patients with MELAS (mean age at initial examination 11.3 years, range 4 to 16 years) were enrolled in the study. Six were followed for more than five years.

RESULTS

On echocardiographic examination, three patients showed increased left ventricular end diastolic posterior wall thickness (LVPWTd), exceeding 140% of the normal value. Four patients, including these three, had an ejection fraction of less than 50%, and two also had increased left ventricular end diastolic volume (LVEDV) exceeding 140% of the normal value (%N). The LVPWTd%N was correlated positively with the LVEDV%N (R = 0.669, p < 0.05) and negatively with the ejection fraction (R = -0.6701, p < 0.05). One patient died of heart failure aged 22 years.

CONCLUSIONS

The cardiomyopathy in MELAS is characterised by an abnormally thick left ventricular wall with progressive dilatation and poor left ventricular contraction developing over several years, indicating hypertrophic cardiomyopathy advancing to dilated cardiomyopathy.

Paroxysmal atrial fibrillation as a cause of potentially lethal ventricular arrhythmia with myocardial ischemia in hypertrophic cardiomyopathy--a case report

The mechanism(s) of myocardial ischemia in hypertrophic cardiomyopathy remain unclear. In this report, the authors present a 75-year-old Japanese woman with nonobstructive hypertrophic cardiomyopathy in whom paroxysmal atrial fibrillation caused severe myocardial ischemia and induced sustained ventricular tachycardia. Her coronary angiogram showed normal findings, and no ischemic changes were provoked by either physical exercise testing or dobutamine stress echocardiography under sinus rhythm. In view of these findings, the rapid ventricular response in the absence of atrial contraction may aggravate or induce myocardial ischemia and predispose patients with hypertrophic cardiomyopathy to develop lethal ventricular arrhythmia.

Effects of phosphoramidon, BQ 788, and BQ 123 on coronary and cardiac dysfunctions of the failing hamster heart

Coronary dysfunctions identified in the presence of chronic heart failure are an important pathophysiologic abnormality that influences the prognosis of the disease. Because the endothelin pathway plays a significant role in the increased peripheral vascular tone associated with heart failure, we hypothesized that the endothelin pathway may be involved in the abnormal coronary vasomotion associated with this pathologic condition. Experiments were carried out in failing hearts (UM-X7.1 cardiomyopathic hamsters, aged 225-250 days) and normal hearts (Syrian LVG hamsters, also aged 225-250 days). Isolated hearts were perfused at constant flow and exposed to the blocker of the generation of endothelin-1 (ET-1), phosphoramidon (10 microM infusion), as well as to the selective ET(A)-receptor antagonist BQ 123 (10 microM infusion) and to a selective ET(B)-receptor antagonist BQ 788 (1 microM infusion). Coronary and cardiac effects of exogenous ET-1 (0.01-100 pmol) were also studied. Phosphoramidon, BQ 788, and BQ 123 did not altered coronary perfusion pressure either in normal or in failing hearts, whereas cardiac contractility was significantly impaired in the presence of phosphoramidon and BQ 123. Coronary sensitivity to exogenous ET-1 did not demonstrate a significant difference between normal and failing hearts [median effective concentration (EC50), 7 pmol in failing hearts vs. 12 pmol in normal hearts; p = NS]. In the presence of exogenous ET-1, cardiac contractility was significantly increased in both groups. In normal hearts, the exogenous ET-1-induced increase in coronary perfusion pressure was completely antagonized by BQ 123, whereas combined administration of BQ 788 and BQ 123 was necessary to induce complete inhibition in failing hearts. The positive inotropic effect elicited by exogenous ET-1 (EC50) was completely abolished in the presence of BQ 123, whereas BQ 788 had no significant effect. Results indicate that the endothelin pathway does not play a significant role in the altered coronary vasomotion observed in this model of chronic heart failure. On the contrary, the endothelin pathway appears to participate in the maintenance of myocardial contractility. According to these observations, administration of an inhibitor of ET-1 synthesis, as well as the use of an ET(A)-receptor antagonist, may be contraindicated in the presence of poor left ventricular function because the endothelin pathway contributes significantly to the maintenance of cardiac contractility.

Angina Pectoris Due to Severe Muscular Bridge in Hypertrophic Cardiomyopathy

We report the case of a 39-year-old male with hypertrophic cardiomyopathy who complained of angina pectoris. The patient was treated with a beta blocker and a calcium antagonist without effect. Myocardial scintigraphy revealed anterior ischemia. Cardiac catheterization and ventriculography revealed severe systolic narrowing of the left anterior descending coronary artery and no significant pressure gradient across the left ventricular outflow tract. Myotomy was performed on a muscular bridge over the left anterior descending coronary artery and the patient's angina was relieved. In young patients with hypertrophic cardiomyopathy who develop angina refractory to medical therapy, a coexisting muscular bridge should be sought.

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.

Hypertrophic cardiomyopathy with apical left ventricular aneurysm

We report a case of hypertrophic cardiomyopathy (HCM) with apical left ventricular aneurysm, which is difficult to review because cases are so rare. A 54-year-old Japanese man was first found to have an electrocardiographic abnormality (T-wave inversion at rest) 19 years ago, and non-obstructive apical HCM without identifiable cause was diagnosed by echocardiography, left ventriculography, and clinical findings. After 19 years, he was admitted because of repeated episodes of palpitation and chest oppression at rest. Widespread left ventricular hypertrophy from the anteroseptal wall to the apex with an apical left ventricular aneurysm was detected by echocardiography, left ventriculography, and cardiac magnetic resonance imaging. Histologic examination of the hypertrophic apical myocardium surrounding the aneurysm showed that the myocardial tissue had been extensively replaced by fibrous tissue containing hypertrophic myocardial fibers, and uptakes of [123I]-metaiodobenzyl guanidine (MIBG) and [123I-] beta-methyliodophenyl pentadecanoic acid (BMIPP) in single-photon emission photography images were reduced despite high myocardial perfusion. On the other hand, histologic examination of the hypertrophic anterior wall revealed myocardial hypertrophy with disorganization; myocardial perfusion and the uptakes of MIBG and BMIPP were preserved. Abnormalities of myocardial fatty acid metabolism and sympathetic neuron activity with preserved perfusion flow and histologic changes such as fibrosis in the apical wall are indicative of apical myocardial injury or ischemia (infarction) without coronary artery stenosis; apical aneurysm may have occurred in severe apical HCM with cavity obliteration up to the midventricular level.

Transthoracic Doppler echocardiographic analysis of phasic coronary blood flow velocity in hypertrophic cardiomyopathy

OBJECTIVE

To use transthoracic Doppler echocardiography to assess coronary blood flow non-invasively in patients with hypertrophic cardiomyopathy.

DESIGN

High frequency transthoracic Doppler echocardiography was used to assess resting phasic coronary velocity patterns in patients with hypertrophic cardiomyopathy and to define the relation between coronary flow patterns and clinical, echocardiographic, and haemodynamic manifestations of this condition.

SETTING

A tertiary referral cardiothoracic centre.

METHODS

Fifteen patients (10 men and five women, mean (SD) age 49 (10.3) years) with asymmetric hypertrophic cardiomyopathy underwent high frequency (5 MHz) transthoracic Doppler echocardiographic assessment of the left anterior descending coronary artery. In addition, standard two dimensional echocardiography was performed. The results were compared with 16 normal participants (nine men and seven women, mean age 61.2 (10.7) years) who had no evidence of cardiac disease.

RESULTS

Biphasic diastolic predominant coronary artery blood velocity profiles were obtained in all patients and controls. Systolic peak blood velocity and velocity time integral were significantly reduced in the hypertrophic cardiomyopathy group compared with controls (11.3 (15.8) cm/s and 1.09 (1.78) cm v 20.5 (13.1) cm/s and 4.23 (2.80) cm, respectively, P < 0.05). A reversed pattern of systolic blood flow velocity was found in three patients with severe anterior wall and septal hypertrophy. During diastole there was prolongation of the diastolic acceleration (203 (53) ms v 110 (60) ms in controls, P < 0.05) and deceleration times (487 (200) ms v 210 (90) ms in controls, P < 0.05). There was no significant difference between those with and without symptoms or a left ventricular outflow tract gradient.

CONCLUSIONS

Patients with hypertrophic cardiomyopathy have abnormal systolic and diastolic coronary flow profiles at rest when measured by transthoracic echocardiography.

Myocardial glucose metabolism is different between hypertrophic cardiomyopathy and hypertensive heart disease associated with asymmetrical septal hypertrophy

Myocardial glucose metabolism has been shown to be heterogeneous in patients with hypertrophic cardiomyopathy (HCM). We tested the hypothesis that myocardial glucose metabolism differs between patients with HCM and those with hypertensive heart disease (HHD) associated with asymmetrical septal hypertrophy. We studied 12 patients with HCM, 7 HHD patients associated with asymmetrical septal hypertrophy using 18F 2-deoxyglucose (FDG) and positron emission tomography. We calculated % FDG fractional uptake in the inter-ventricular septum and posterolateral wall. Heterogeneity of FDG uptake was evaluated by % interregional coefficient of variation of FDG fractional uptake in each wall segment. In both the interventricular septum and posterolateral wall, % FDG fractional uptake was not significantly different between the two groups. The % interregional coefficient of variation for both interventricular septum (10.6 +/- 1.6 vs. 4.1 +/- 0.5, p < 0.01) and posterolateral wall (5.9 +/- 0.7 vs. 3.8 +/- 0.5, p < 0.05) was significantly larger in patients with HCM than in HHD patients associated with asymmetrical septal hypertrophy. Echocardiography demonstrated that the degree of asymmetrical septal hypertrophy was similar between the two groups. These results suggest that myocardial glucose metabolism may be more heterogeneous in patients with HCM compared to HHD patients associated with asymmetrical septal hypertrophy, although the left ventricular shape is similar. The difference in the heterogeneity might have resulted from differences in the pathogeneses of the two diseases.

Heterogeneity of myocardial fluoro-18 2-deoxyglucose uptake in patients with apical hypertrophic cardiomyopathy

We have shown that myocardial glucose metabolism is heterogeneous in patients with hypertrophic cardiomyopathy. It is not known, however, whether glucose metabolism is impaired in patients with apical hypertrophic cardiomyopathy, which is fairly common in Japan. We studied 7 patients with apical hypertrophic cardiomyopathy and 5 normal subjects using fluoro-18 2-deoxyglucose (FDG) and positron emission tomography (PET). We calculated regional FDG fractional uptake and the inter-regional coefficient of variation (CV) of FDG fractional uptake in the interventricular septal, anteroapical, and posterolateral regions. The regional FDG fractional uptake was similar in the 2 groups and among the 3 different segments within each group. However, the inter-regional CV of FDG fractional uptake was increased in the anteroapical wall segment of the patient group compared with the control group and also with the other 2 regions in the patient group. The results did not differ when we studied another 5 patients and 6 normal control subjects with a PET scanner with higher spatial resolution. These data suggest that myocardial glucose metabolism may be impaired in the anteroapical wall segment of patients with apical hypertrophic cardiomyopathy.

Acute hemodynamic deterioration during rapid atrial pacing in patients with hypertrophic cardiomyopathy

BACKGROUND AND HYPOTHESIS

Supraventricular tachycardia and ventricular tachycardia are often observed in patients with hypertrophic cardiomyopathy (HCM) and they often alter the clinical features of HCM. We examine the influence of supraventricular tachycardia on cardiac function and assess the clinical characteristics of patients with HCM.

METHODS

We studied 32 patients with HCM and 8 normal volunteers using echocardiography under transesophageal rapid atrial pacing.

RESULTS

Presyncope-associated hypotension was observed during rapid atrial pacing in 8 HCM patients, but in none of the normal controls. During rapid atrial pacing (144 +/- 8 beats/min in HCM, 146 +/- 5 beats/min in controls), systolic blood pressure (SBP), the product of left ventricular filling volume (FV) and heart rate, and fractional shortening (%FS) in the HCM patients decreased significantly compared with the basal values (138 +/- 19 mmHg vs. 99 +/- 24 mmHg, 5.0 +/- 1.2 l/min vs. 2.9 +/- 0.9 l/min, 41.7 +/- 6.2% vs. 35.2 +/- 6.0%, respectively), but these decreases were not observed in normal controls. The decrement of SBP during rapid atrial pacing in HCM patients with a history of syncope was more marked than that in those without such history. The decrement correlated positively with the indices of left ventricular hypertrophy (maximal wall thickness and wall thickness index) and with %FS, and correlated negatively with the endsystolic left ventricular diameter at rest.

CONCLUSIONS

In some patients with HCM, supraventricular tachycardia causes marked hemodynamic deterioration that may be related to a history of syncope, marked hypertrophy, hyperkinesis, small cavity size, and small filling volume of the left ventricle.

Regional wall motion analysis by dobutamine stess echocardiography to distinguish between ischemic and nonischemic dilated cardiomyopathy

To distinguish between ischemic and nonischemic dilated cardiomyopathy (DCM), we studied 43 patients with left ventricular dysfunction (15 ischemic and 28 nonischemic detected by coronary angiography) by dobutamine stress echocardiography. At rest, there were more normal segments (p<0.001) and a trend toward more akinetic segments (p, not significant) per ischemic than per nonischemic DCM patient. However, either at rest or with low-dose dobutamine, individual data largely overlapped. At peak dose, in ischemic DCM, regional contraction worsened in many normal or dys-synergic regions at rest (in the latter case after improvement with low-dose dobutamine); in contrast, in nonischemic DCM, further mild improvement was observed in a variable number of left ventricular areas. Thus with peak-dose dobutamine, more akinetic and less normal segments were present per ischemic than per nonischemic DCM patient (both, p<0.001). A value of six or more akinetic segments was 80% sensitive and 96% specific for ischemic DCM. Our data show that analysis of regional contraction by dobutamine stress echocardiography can distinguish between ischemic and nonischemic DCM.

Changes in coronary sinus pH during dipyridamole stress in patients with hypertrophic cardiomyopathy

OBJECTIVES

The presence of angina pectoris and myocardial scarring in patients with hypertrophic cardiomyopathy (HCM) suggests that myocardial ischemia is a factor in the pathophysiology of the disease. The clinical evaluation of ischaemia is problematic in HCM as baseline electrocardiographic abnormalities are frequent and thallium-201 perfusion abnormalities correlate poorly with anginal symptoms. Coronary sinus pH measurement using a catheter mounted pH electrode is a validated sensitive technique for the detection of myocardial ischaemia.

METHODS AND RESULTS

11 patients with HCM and chest pain (eight men; mean (SD) (range) age 36 (11) (19-53) years) and six controls (two men; mean (SD) (range) age 49 (11) (31-62) years) with atypical pain and normal coronary angiograms were studied. Eight patients with HCM had baseline ST segment depression of > or = 1 mm and four had reversible perfusion defects during stress 201TI scintigraphy. A catheter mounted hydrogen ion sensitive electrode was introduced into the coronary sinus and pH monitored continuously during dipyridamole infusion (0.56 mg/kg over four min). The maximal change in coronary sinus pH during dipyridamole stress was greater in patients with HCM than in controls (0.082 (0.083) (0 to -0.275) v 0.005 (0.006) (0 to -0.012), P = 0.02). In six patients (four men; mean (SD) (range) age 29 (9) (19-40 years) the development of chest pain was associated with a gradual decline in coronary sinus pH (mean 0.123 (0.089)), peaking at 442 (106) s. There were no relations among left ventricular dimensions, maximal wall thickness, and maximum pH change. In patients with HCM there was a correlation between maximum pH change and maximum heart rate during dipyridamole infusion (r = 0.70, P = 0.02).

CONCLUSION

This study provides further evidence that chest pain in patients with HCM is caused by myocardial ischaemia. The role of myocardial ischaemia in the pathophysiology of the disease remains to be determined but coronary sinus pH monitoring provides a method for quantifying and prospectively assessing its effects on clinical presentation and prognosis.

Incidence of hypertrophic cardiomyopathy in hypothyroidism

In 13 consecutive severely hypothyroid patients no sign of endocrine cardiomyopathy in the form of asymmetric septal hypertrophy (ASH) could be disclosed by M-mode and two-dimensional (2D) echocardiography on examination prior to thyroxine replacement therapy. In previous investigations ASH was demonstrated to be almost invariably present in untreated hypothyroidism irrespective of thyrotropin levels. Consequently application of positive inotropic and afterload reducing agents that may invoke deleterious effects in ASH has been considered hazardous in hypothyroidism even when indicated by concurrent other heart disease. Determination of exact confidence limits reveals that the proportional incidence of hypothyroid hypertrophic cardiomyopathy could not exceed 24.7% with 95% probability. We conclude that ASH is not necessarily inherent in hypothyroidism.

Sudden cardiac death in patients with hypertrophic cardiomyopathy: from bench to bedside with an emphasis on genetic markers

Hypertrophic cardiomyopathy (HCM) is the most common cause of death in the young, particularly in young competitive athletes. Death often occurs suddenly in asymptomatic, apparently healthy individuals. Several clinical parameters as well as genetic factors have been characterized that can identify those HCM patients who are at high risk for sudden cardiac death (SCD). The clinical parameters that have some predictive values for SCD in HCM patients are the following: a prior history of SCD, a family history of SCD, history of syncope, symptomatic ventricular tachycardia on Holter monitoring, inducible ventricular tachycardia during electrophysiologic studies, and myocardial ischemia in children with HCM. Recent identification of mutations in the beta myosin heavy chain gene and genotype-phenotype correlation in HCM patients have shown that the beta myosin heavy chain mutations are also prognosticators in HCM families. Several mutations such as Arg403Gln and Arg719Gln are associated with a high incidence of SCD, while Leu908Val mutation is associated with a benign course and a low incidence of SCD in HCM families. Additional genetic factors such as a polymorphism in angiotensin-converting enzyme I gene may also contribute to a high incidence of SCD in HCM families. Identification and characterization of HCM patients at high risk for SCD provide the opportunity to render prophylactic therapeutic interventions, such as implantation of defibrillators, in these individuals.

Natural history of hypertrophic cardiomyopathy

Images

Effect of verapamil on absolute myocardial blood flow in hypertrophic cardiomyopathy

Angina, despite angiographically normal coronary arteries, is a common symptom in patients with hypertrophic cardiomyopathy (HC). Verapamil has been shown to ameliorate silent myocardial perfusion defects documented by thallium-201 in patients with HC. The aim of this study was to investigate the effects of verapamil on absolute regional myocardial blood flow and flow reserve, measured by positron emission tomography (PET) in patients with HC. Echocardiography, exercise stress testing, and measurements of myocardial blood flow at rest and after administration of intravenous dipyridamole (0.56 mg/kg) were undertaken in 20 patients with HC at baseline study and 8 +/- 2 weeks after double-blind randomization to either slow-release verapamil 240 mg or placebo once daily. During treatment, resting myocardial blood flow in the interventricular septum was 0.81 +/- 0.23 versus 0.96 +/- 0.42 ml/min/g in the placebo and verapamil group, respectively (p = NS between groups and when compared with respective baseline study); resting myocardial blood flow in the left ventricular free wall was 0.67 +/- 0.17 versus 0.74 +/- 0.45 ml/min/g, respectively (p = NS). After dipyridamole infusion, myocardial blood flow in the interventricular septum was 1.42 +/- 0.52 versus 1.92 +/- 1.23 ml/min/g (p = NS between groups and when compared with respective baseline study); myocardial blood flow in the left ventricular free wall was 1.25 +/- 0.41 versus 1.68 +/- 1.37 ml/min/g, respectively (p = NS).(ABSTRACT TRUNCATED AT 250 WORDS)

Vasodilatory capacity of coronary resistance vessels in dilated cardiomyopathy

Both the endothelium-dependent and endothelium-independent vasodilatory responses of coronary resistance vessels were studied in patients with dilated cardiomyopathy (DCM). A 3F coronary Doppler catheter was placed in the proximal left anterior descending artery in 14 patients with DCM and in 10 patients with chest pain syndrome and a normal heart (control subjects). The ratio of maximum mean coronary blood flow velocity after intracoronary administration of the endothelium-independent vasodilator papaverine (10 mg) to resting mean coronary blood flow velocity (Vp/Vo) in patients with DCM was diminished compared with that in control subjects (2.2 +/- 0.6 vs 4.1 +/- 0.9, p < 0.001). The ratio after administration of the endothelium-dependent vasodilator acetylcholine (40 micrograms) (Va/Vo) in 10 DCM patients was also diminished compared with that in seven control subjects (1.3 +/- 0.5 vs 2.4 +/- 0.8, p < 0.01). In DCM patients, Vp/Vo was correlated with left ventricular end-diastolic pressure (r = -0.48, p < 0.05), left ventricular end-diastolic volume index (r = -0.68, p < 0.01), ejection fraction (r = 0.75, p < 0.01), and left ventricular end-diastolic wall stress (r = -0.73, p < 0.01). However, Va/Vo was not correlated with any of these parameters. These results indicate that impairment of the vasodilatory capacity of coronary resistance vessels in DCM may be related to endothelial dysfunction and to an extravascular factor resulting from left ventricular dysfunction.

Phasic coronary flow characteristics in patients with hypertrophic cardiomyopathy: a study by coronary Doppler catheter

Abnormal patterns of coronary flow velocity have been observed in patients with symmetric left ventricular hypertrophy in conditions such as aortic stenosis and systemic hypertension. However, phasic coronary flow characteristics have not been investigated in patients with asymmetric left ventricular hypertrophy in hypertrophic cardiomyopathy. The purpose of this study was to assess phasic coronary flow characteristics and their relation to echocardiographic and hemodynamic parameters in patients with hypertrophic cardiomyopathy. Coronary flow velocity was recorded in the left anterior descending artery with a 20 MHz Doppler catheter in eight patients with hypertrophic nonobstructive cardiomyopathy and eight control subjects with normal coronary arteries. Flow reversals observed in systole in all patients with hypertrophic cardiomyopathy, and the time velocity integrals of systolic flow were significantly smaller in patients with hypertrophic cardiomyopathy than in control subjects (-1.5 +/- 1.7 versus 4.3 +/- 1.2 cm; p < 0.01). The time from the beginning of diastole to peak diastolic velocity corrected by the square root of R-R interval (square root of RR) was prolonged significantly, and the velocity half-time from peak diastolic velocity corrected by square root of RR was shorter in the patients with hypertrophic cardiomyopathy compared with those in the control subjects (6.8 +/- 2.0 msec versus 4.0 +/- 0.6 msec [p < 0.01] and 9.2 +/- 4.9 msec versus 13.9 +/- 2.0 msec [p < 0.05], respectively). Peak velocity and time velocity integral of flow reversal showed significant correlations with anterior ventricular septal thickness (y = -0.5x + 13.5, r = 0.8, and p < 0.01; y = -1.3 +/- 16.8, r = 0.8, and p = 0.024, respectively), the septal/free wall thickness ratio (y = -0.1x + 1.1, r = 0.8, and p < 0.01; y = -0.2x + 1.4, r = 0.9, and p < 0.01, respectively), and the degree of narrowing of the first septal perforator arteries (y = 1.9x + 91.6, r = 0.8, and p = 0.012; y = 6.1x + 80.6, r = 0.9, and p < 0.01, respectively). In conclusion, flow reversal in systole and slow acceleration and rapid deceleration in diastole were characteristics in patients with hypertrophic cardiomyopathy. Flow reversal might be related to the degree of left ventricular asymmetry and compression of the septal perforator arteries.

Assessment of flow profile of left anterior descending coronary artery in hypertrophic cardiomyopathy by transesophageal pulsed Doppler echocardiography

This study assessed the flow velocity profiles of the left anterior descending coronary artery (LAD) in 7 patients with nonobstructive hypertrophic cardiomyopathy (HC) and in 6 normal subjects by transesophageal pulsed Doppler echocardiography, and evaluated their characteristics and the hemodynamic determinants. Systolic peak flow velocity of the LAD (7 +/- 30 cm/sec) was significantly lower in patients with HC than in normal subjects (34 +/- 11 cm/s, p < 0.05), and there was a significant inverse correlation between systolic peak flow velocity and the thickness of the ventricular septum (r = 0.81, p < 0.01). In 2 cases of HC with ventricular septal thickness of > 20 mm, a remarkable systolic reverse flow was observed in the LAD. However, there was no significant difference in diastolic peak flow velocity between HC and normal subjects. During early diastole, the acceleration time of LAD flow velocity was significantly prolonged (210 +/- 67 vs 95 +/- 15 ms, p < 0.01) and the acceleration rate was significantly decreased (3.6 +/- 2.0 vs 6.6 +/- 1.8 m/s2, p < 0.02) in patients with HC. The time constant of the left ventricular pressure decay was significantly prolonged in patients with HC (55 +/- 6 ms) compared with normal subjects (39 +/- 2 ms, p < 0.001). In HC, increased intramural perivascular pressure of the thickened ventricular septum during systole may be attributed to systolic LAD flow pattern. However, the early and mid-diastolic LAD flow pattern may be affected by impaired left ventricular relaxation.

Regional systolic function, myocardial blood flow and glucose uptake at rest in hypertrophic cardiomyopathy

Decreased 18fluorodeoxyglucose (FDG) uptake and blood flow at rest in the ventricular septum, as compared with the lateral wall, have been reported in mildly symptomatic patients with hypertrophic cardiomyopathy (HC). To assess whether regional metabolic heterogeneity in patients with HC is related to heterogeneous regional systolic function, 10 symptomatic patients (mean age 36 +/- 17 years) with HC and no coronary artery disease underwent positron emission tomography with oxygen-15-water and FDG, and nuclear magnetic resonance imaging at rest to assess regional anatomy and systolic function. Regional absolute blood flow was similar between the ventricular septum and lateral wall. In contrast, FDG activity was significantly greater in the lateral wall than in the septum (1,023 +/- 588 vs 767 +/- 388 nCi/ml, respectively; p < 0.01). However, regional systolic wall thickening was also significantly greater in the lateral wall than in the septum (5.3 +/- 4.3 vs 2.4 +/- 4.0 mm, respectively; p < 0.001). Patients were then divided into group A (n = 5) with similar regional wall thickening in the septum and lateral wall, and group B (n = 5) with greater thickening in the lateral wall than in the septum. In both groups, regional blood flow was similar between the septum and lateral wall. However, the regional septal-to-lateral FDG activity ratio was 0.97 +/- 0.31 in group A, and 0.74 +/- 0.25 in group B (p < 0.01); the ratio in group A did not differ from that in 5 normal subjects (1.02 +/- 0.58).(ABSTRACT TRUNCATED AT 250 WORDS)

Coronary flow reserve in patients with dilated cardiomyopathy

Coronary flow reserve was studied in patients with dilated cardiomyopathy. A 3F coronary Doppler catheter was placed in the proximal left anterior descending artery in each of 10 patients with dilated cardiomyopathy (CDM group), seven patients with coronary artery disease that involved only the left anterior descending artery (CAD group), and seven patients with chest pain syndrome and normal hearts (control group). Coronary flow reserve was calculated as the ratio of the maximum mean coronary blood flow velocity after intracoronary administration of papaverine (10 mg) to resting flow velocity (M/R). The time until maximum flow velocity was reached after papaverine administration (Tmax) was also measured. M/R was lower in the DCM (p < 0.001) and CAD (p < 0.001) groups when compared with the control group. Tmax was not abnormal in the DCM group but was prolonged in the CAD group (p < 0.05). In the DCM group, the M/R ratio correlated with the left ventricular end-diastolic pressure (r = -0.69; p < 0.05), the left ventricular end-diastolic volume index (r = -0.7; p < 0.05), the ejection fraction (r = 0.82; p < 0.01), the left ventricular mass (r = -0.7; p < 0.05), and the left ventricular end-diastolic wall stress (r = -0.84; p < 0.001). These results indicate that coronary flow reserve was decreased in patients with dilated cardiomyopathy and that the mechanism of its reduction may differ from that in patients with coronary artery disease.

Differentiation between primary dilated cardiomyopathy and ischemic cardiomyopathy based on right ventricular performance

The differentiation of primary dilated cardiomyopathy from ischemic cardiomyopathy, though important, is difficult clinically and may require coronary angiography or metabolic imaging. Both patient groups have severe left ventricular dysfunction and severe wall motion abnormality. This study examined the differences in right ventricular performance between the two groups. There were 90 patients with a left ventricular ejection fraction less than 30% who had coronary angiography and multigated radionuclide angiography (MUGA). Of these, 69 had ischemic cardiomyopathy and 21 had primary cardiomyopathy. The left ventricular ejection fraction was similar; 22 +/- 6% in ischemic cardiomyopathy and 21 +/- 6% in primary cardiomyopathy. However, the right ventricular ejection fraction was higher in ischemic cardiomyopathy (38 +/- 16% versus 29 +/- 12%, p less than 0.01). There were 59 patients with right ventricular ejection fraction greater than or equal to 30%, of whom 50 patients (85%) had ischemic cardiomyopathy. The left ventricular and right ventricular volumes were determined by a count-based method. The right ventricular end-diastolic volume/left ventricular end-diastolic volume ratio was 0.57 in ischemic cardiomyopathy and 1.07 in primary cardiomyopathy (p less than 0.05). Thus assessment of right ventricular function may help differentiate primary from ischemic cardiomyopathy; a preserved right ventricular performance is highly suggestive of ischemic cardiomyopathy.

Long-term course and cardiac sympathetic nerve activity in patients with hypertrophic cardiomyopathy

OBJECTIVE

To investigate the relation between regional myocardial sympathetic nerve activity and the electrocardiographic and cardiac functional changes in hypertrophic cardiomyopathy.

DESIGN

A retrospective study to compare the findings of myocardial scintigraphy with iodine-123 metaiodobenzylguanidine (MIBG) and the serial electrocardiographic changes.

SETTING

Myocardial scintigraphy was performed with iodine-123 MIBG and thallium-201 and single photon emission computed tomography (SPECT) in the division of nuclear medicine of Kanazawa University Hospital. Both SPECT studies were performed within a week.

PATIENTS

22 patients with hypertrophic cardiomyopathy classified according to their serial electrocardiographic changes--namely, 15 patients with an increase in or the appearance of a negative T wave (group A) and seven patients with a conduction disturbance or a decrease in or disappearance of the negative T wave (group B). The mean follow up period was 45 (range 12-143) months.

RESULTS

Group B showed a high rate of decreased activity or defects in MIBG uptake compared with group A (p less than 0.005). The areas of decreased activity or defects corresponded with the hypertrophied portion of the left ventricular wall. Although the early myocardial uptake (MIBG: thallium ratio) was similar in both groups, the mean (SD) MIBG clearance rate was significantly higher (p less than 0.05) in group B (0.25 (0.17)) than in group A (0.10 (0.15)).

CONCLUSION

Abnormalities of regional myocardial sympathetic nerve activity may be important in patients with hypertrophic cardiomyopathy and suspected progression of myocardial damage.

Differences in myocardial fluoro-18 2-deoxyglucose uptake in young versus older patients with hypertrophic cardiomyopathy

The purpose of this study was to determine whether regional myocardial glucose use in patients diagnosed as having hypertrophic cardiomyopathy (HC) at a younger age differs from that in those diagnosed at middle to old age. Sixteen patients with HC (group 1 aged less than 40 years (n = 8); group 2 aged greater than 40 (n = 8) were studied using positron emission tomography and fluoro-18 2-deoxyglucose (FDG). All patients were diagnosed as having HC within 6 years of the study. Contiguous regions of interest were selected circumferentially on each cross-sectional image of the left ventricular wall. In each region of interest, % FDG fractional uptake was calculated. In each patient, % left ventricular FDG fractional uptake was determined as a mean value of % FDG fractional uptake in each region of interest. Moreover, as a measure of nonhomogeneity, the % interregional coefficient of variation in FDG fractional uptake was calculated in each patient. Whereas % left ventricular FDG fractional uptake did not differ between the 2 groups, the % interregional coefficient of variation in FDG fractional uptake was increased in group 1 compared with that in group 2 (11.5 +/- 3.6 vs 7.4 +/- 1.6%; p less than 0.02). Interventricular septum/left ventricular posterior wall thickness ratio and total counts in cross-sectional image did not differ between the 2 groups. These data suggest that patients diagnosed as having HC at a younger age have more nonhomogeneous myocardial metabolic characteristics than do patients diagnosed at middle or old age, and support the notion that HC in the young may be different from that in the middle-aged or elderly.

Adenine nucleotide metabolism and contractile dysfunction in heart failure--biochemical aspects, animal experiments, and human studies

In myocardial hypertrophy and heart failure a series of adaptational changes occur some multiplying contractile units, others slowing shortening velocity and increasing economy of contraction. The demonstration of energy-saving mechanisms in heart failure has prompted further investigations of energy providing and utilizing metabolic pathways. The use of myocardial ATP as a substrate occurs mainly at the myosin-ATPase and at the Ca-ATPase of the sarcoplasmic reticulum. As the Michaelis constant of both enzymes for ATP is in the micromolar (microM) range, whereas cellular ATP content is about 5000 microM, these enzymes are not controlled by the availability of ATP as a substrate. In experimental heart failure in large animals, normal or reduced creatine phosphate levels (in most cases together with normal adenine nucleotides) have been described. Reduced creatine phosphate is found in models with increased oxygen consumption, and creatine phosphate may buffer the ATP pool in these models. In human heart failure due to dilated cardiomyopathy, where resting oxygen consumption per unit mass and lactate extraction are normal in most patients, normal adenine nucleotides, creatine phosphate, and mitochondrial function have been described in the initial studies. These results have been challenged by one study showing decreased ATP levels in dilated cardiomyopathy, correlating with the decrease in ejection fraction. However, only ATP has been measured in this study, whereas total adenine nucleotides may be a more suitable parameter. Recently published results have again demonstrated normal ATP and total adenine nucleotides in human heart failure. In the same patients, significantly decreased myocardial norepinephrine was measured, indicating that metabolic changes had occurred in these hearts, but were independent of adenine nucleotides.(ABSTRACT TRUNCATED AT 250 WORDS)

Coronary vasodilatation and improved myocardial lactate metabolism after angiotensin converting enzyme inhibition with cilazapril in patients with congestive heart failure

The effects of angiotensin converting enzyme inhibition on systemic and coronary hemodynamics and on myocardial lactate metabolism were investigated before and 2 and 6 hours after cilazapril at rest and during supine submaximal exercise in 10 patients with New York Heart Association class II or III chronic congestive heart failure. Angiotensin converting enzyme inhibition, indicated by a significant increase in plasma renin activity, resulted in significant reductions in blood pressure and systemic vascular resistance. Myocardial oxygen demand decreased (resting double product 10.9 +/- 3.7 vs 12.2 +/- 3.8 mm Hg beats/min 10(-3); p less than 0.05), but coronary sinus blood flow remained unchanged and calculated coronary resistance decreased (0.45 vs 0.5 units, rest 6 hours; p less than 0.05) suggesting coronary vasodilatation. Changes in coronary vascular resistance were directly related to changes in systemic vascular resistance (r = 0.75, p less than 0.5). Myocardial lactate extraction increased at rest (47 +/- 60 vs 134 +/- 132 mumol/min; p less than 0.5) and during exercise (27 +/- 54 vs 491 +/- 317 mumol/min; p less than 0.05) both in patients with coronary artery disease (n = 5) and idiopathic dilated cardiomyopathy (n = 5). Resting lactate production was converted to lactate extraction in two patients with coronary artery disease. Neither plasma catecholamine nor atrial natriuretic peptide concentrations changed significantly. The results suggest coronary vasodilation and improved aerobic myocardial metabolism by angiotensin converting enzyme inhibition in patients with congestive heart failure.

Left ventricular regional relaxation and its nonuniformity in hypertrophic nonobstructive cardiomyopathy

BACKGROUND

Regional nonuniformity has been suggested to be closely related to left ventricular (LV) relaxation in diseased heart. The purpose of the present study was to assess LV global and regional relaxation in patients with nonobstructive hypertrophic cardiomyopathy (HCM).

METHODS AND RESULTS

Left ventriculography was conducted simultaneously with pressure micromanometry in 10 normal control subjects and 11 patients with nonobstructive HCM. LV silhouettes in the right anterior oblique projection were divided into eight regions, and regional wall stress during isovolumic relaxation was computed for six regions from the midventricle to the apex. In HCM patients, isovolumic relaxation time (IRT) and the time constant of LV pressure decrease (Tp) were greater than in control subjects (IRT, 84 +/- 13 versus 66 +/- 6 msec; Tp, 51 +/- 8 versus 36 +/- 5 msec, respectively; p less than 0.01). In HCM patients, the (-)dP/dt upstroke pattern was convex-downward, and dP/dt(20/60), the ratio of dP/dt values 20 and 60 msec after peak (-)dP/dt, was less than in control subjects (1.46 +/- 0.16 versus 2.15 +/- 0.14, p less than 0.01). These findings suggest that there is impaired LV relaxation in HCM patients. End-systolic regional wall stress was lower, and the time constant of regional stress decrease (Tst) was prolonged for each region in HCM patients compared with control subjects. In the HCM group, Tst tended to be more prolonged in regions with increased wall thickness than in regions with normal wall thickness (60 +/- 15 versus 50 +/- 11 msec, p less than 0.01). The coefficient of variation for Tst values in six areas of the left ventricle was calculated in each subject and was greater in HCM patients than in control subjects (13 +/- 7% versus 7 +/- 3%, p less than 0.05), indicating regional nonuniformity in Tst during isovolumic relaxation in HCM patients.

CONCLUSIONS

Significant correlations existed between the coefficients of variation for Tst and Tp (r = 0.80, p less than 0.01), IRT (r = 0.79, p less than 0.01), and dP/dt(20/60) (r = -0.67, p less than 0.05) in the HCM group. Thus, regional nonuniformity is closely related to the impairment of LV relaxation in HCM.

Evidence for or against efficacy of beta-blockers and aspirin for management of feline cardiomyopathies

Feline myocardial diseases today are largely represented by disorders involving LV hypertrophy. They may be attended by arrhythmias, congestive heart failure, systemic hypertension, thromboembolic complications, and sudden death. These structural myocardial disorders and their hemodynamic and electrocardiographic derangements may cause or result in variable degrees of diastolic dysfunction. Propranolol and aspirin represent two agents commonly employed to treat feline cardiomyopathies for more than 15 years. Nevertheless, clinical data describing their effect on morbidity and mortality are lacking. It is likely that propranolol administered at moderate to high doses effects favorable responses in some cats with clinical signs attributable to severe hypertrophy, outflow obstruction, or tachyarrhythmias. It is unknown whether clinical improvements are due to direct myocardial effects or (more likely) secondary responses to a beta-adrenergic blockade reduction in heart rate or contractility. Personal experience also indicates that high numbers of cats have received the drug for many years in combination with other therapies (especially furosemide) and remain in a compensated state of heart failure without untoward drug effects. On the other hand, many cardiomyopathic cats experience heart failure, arrhythmias, and death despite treatment with beta-blocking agents. Feline thromboembolism is a devastating complication of cardiomyopathic disorders. Until or unless the primary cause(s) of current diseases is elucidated to promote disease reversal, factors responsible for thrombus formation will accompany the heart diseases, protected from effective management. It appears unlikely that aspirin as currently recommended produces any obvious benefit in treating or preventing thromboembolism. Modifications of therapeutic protocols prescribing these frequently used drugs await well-constructed clinical trials evaluating their efficacy with respect to cardiovascular morbidity and mortality.

Differentiating cardiomyopathy of coronary artery disease from nonischemic dilated cardiomyopathy utilizing positron emission tomography

To determine if imaging of blood flow (using N-13 ammonia) and glucose metabolism (using F-18 2-deoxyglucose) with positron emission tomography can distinguish cardiomyopathy of coronary artery disease from nonischemic dilated cardiomyopathy, 21 patients with severe left ventricular dysfunction who were evaluated for cardiac transplantation were studied. The origin of left ventricular dysfunction had been previously determined by coronary angiography to be ischemic (11 patients) or nonischemic (10 patients). Images were visually analyzed by three observers on a graded scale in seven left ventricular segments and revealed fewer defects in dilated cardiomyopathy compared with ischemic cardiomyopathy for N-13 ammonia (2.7 +/- 1.6 versus 5 +/- 0.6; p less than 0.03) and F-18 deoxyglucose (2.8 +/- 2.1 versus 4.6 +/- 1.1; p less than 0.03). An index incorporating extent and severity of defects revealed more homogeneity with fewer and less severe defects in subjects with nonischemic than in those with ischemic cardiomyopathy as assessed by imaging of flow (2.8 +/- 1.8 versus 9.2 +/- 3; p less than 0.001) and metabolism (3.8 +/- 3.3 versus 8.5 +/- 3.6; p less than 0.005). Diagnostic accuracy for distinguishing the two subgroups by visual image analysis was 85%. Using previously published circumferential count profile criteria, patients with dilated cardiomyopathy had fewer ischemic segments (0.4 +/- 0.8 versus 2.5 +/- 2 per patient; p less than 0.01) and infarcted segments (0.1 +/- 0.3 versus 2.4 +/- 1.4 per patient; p less than 0.001) than did patients with cardiomyopathy of coronary artery disease. The sensitivity for differentiating the two clinical subgroups using circumferential profile analysis was 100% and the specificity 80%. An index incorporating both number and severity of defects derived from circumferential profile analysis was significantly lower in subjects with dilated cardiomyopathy than in ischemic cardiomyopathy (0.3 +/- 0.8 versus 2.7 +/- 2.4; p less than 0.005). Thus, noninvasive positron emission tomographic imaging with N-13 ammonia and F-18 deoxyglucose is helpful in distinguishing patients with severe left ventricular dysfunction secondary to coronary artery disease from those with nonischemic cardiomyopathy, and a semiquantitative index such as circumferential profile analysis is superior to that of visual analysis alone.

Hypertrophic cardiomyopathy: prognosis with medical or surgical therapy

Over the past 30 years, knowledge of the natural history and effects of therapy in patients with hypertrophic cardiomyopathy has expanded greatly, but progress has been hampered by its variable patterns of expression. Many but not all patients show symptomatic improvement with medical treatment. Chronic beta blockage does not appear to affect long-term survival, whereas results with calcium channel blockade by verapamil have been encouraging; however, they await confirmation, and verapamil may be hazardous in some patients with severe left ventricular (LV) outflow tract obstruction and elevated LV end-diastolic pressure. Reported beneficial effects of amiodarone on survival also require further study. Surgical therapy has become the treatment of choice for medically refractory patients with proven outflow tract obstruction. In several centers, the operative risk is low, and long-term follow-up demonstrates prolonged symptomatic relief. It is hoped that work currently underway will provide more definitive information on the long-term effects of the role of calcium channel blockers, antiarrhythmic medications, and the long-term effects of surgical therapy on survival of patients with this disorder.

Syndrome of diminished vasodilator reserve of the coronary microcirculation (microvascular angina or syndrome X): diagnosis by combined atrial pacing and thallium 201 imaging--a case report

Patients with angina-like chest pain without evidence of epicardial coronary artery disease or coronary arterial vasospasm are becoming increasingly recognized. These are often related to noncardiac causes including esophageal, musculoskeletal, and hyperventilatory or panic states. However, recently a subgroup of such patients are being recognized as having true myocardial ischemia and chest pain on the basis of diminished coronary microvascular vasodilatory reserve (microvascular ischemia or Syndrome X). The authors describe such a patient who was found to have replication of anginal pain associated with a reversible ischemic defect on thallium 201 imaging during atrial pacing, suggesting ischemia in this myocardial segment. Resolution of angina and ST segment electrocardiographic changes of ischemia occurred with cessation of pacing. We believe this is the first report of a patient with this form of myocardial ischemia diagnosed by this method and should be considered in patients with anginal chest pain after significant coronary artery disease and coronary vasospasm have been excluded.

Decreased coronary vasodilatory capacity in hypertrophic cardiomyopathy determined by split-dose thallium-dipyridamole myocardial scintigraphy

Split-dose thallium-dipyridamole myocardial scintigraphy was performed in patients with nonobstructive hypertrophic cardiomyopathy (HC) who had angiographically normal coronary arteries. The dipyridamole-induced increases in thallium-201 uptake, calculated to evaluate coronary vasodilatory capacity, were significantly lower in 30 patients with HC than in 13 control subjects (177 +/- 58 vs 281 +/- 46%) and the reductions were observed in both the septal and lateral segments. The reductions of the septal segment in HC patients were significantly greater than those in 10 hypertensive patients with comparable degrees of septal hypertrophy. Of patients with HC, 16 had increases in thallium uptake well below the normal range. Compared with those having normal increases, these patients had significantly lower exercise duration (11 vs 15 minutes), with 33% having ST depression develop at a workload less than or equal to 80 watts. These data indicate that approximately one-half of patients with HC have impaired coronary vasodilatory capacity that could be an important pathophysiologic abnormality of HC resulting in the development of myocardial ischemia and the impairment of cardiac performance during exercise.

Follow-up study of morbidity in patients with angina pectoris and normal coronary angiograms and the value of investigation for esophageal dysfunction

A postal questionnaire was used to assess the symptoms, use of medical facilities, and employment status of patients with angina pectoris and normal coronary angiograms following cardiac catheterization. In a retrospective study of 187 patients, 66 had left ventricular dysfunction demonstrated by abnormal regional wall motion and 121 had normal left ventricular function. At follow-up twelve to forty-six months following catheterization, 89% with left ventricular dysfunction and 82% with normal ventricular function had continued to experience chest pain. There was no significant change in the admission rate to hospital because of chest pain or the proportion of patients who were working, after catheterization as compared with before, in either group. Some patients with left ventricular regional wall motion abnormalities appeared to have progressive left ventricular dysfunction. In a prospective study of 63 patients, detailed investigation of esophageal function was performed. Twenty-two patients had left ventricular wall motion abnormalities. The majority of the 41 patients with normal left ventricular wall motion had esophageal abnormalities that were treated appropriately. At follow-up six to twenty-four months following catheterization significantly fewer patients with normal left ventricular function continued to experience chest pain compared with those with left ventricular dysfunction. Following catheterization the hospital admission rate fell significantly and the proportion of patients working increased significantly in the group with normal left ventricular function. The hospital admission rate and employment status of patients with left ventricular dysfunction did not change significantly following angiography. These findings suggest, therefore, that investigation for and treatment of esophageal dysfunction should be performed in patients with angina pectoris, normal coronary angiograms, and normal left ventricular function.