Hypertrophic cardiomyopathy

General Anesthetic Management of a Patient With Hypertrophic Cardiomyopathy for Oral Surgery: Did Digitalis Contribute to Bradycardia?

Stabilization of circulatory dynamics is a critical issue in the anesthetic management of patients with hypertrophic cardiomyopathy (HCM). In this report, we managed general anesthesia for a 74-year-old male patient with nonobstructive HCM who developed circulatory instability intraoperatively. Severe bradycardia measuring 35 beats/min and hypotension measuring 78 mm Hg systolic were observed during surgery. Using stroke volume variation and stroke volume from the FloTrac as indices, successful circulatory management was performed with dopamine. The hypotension and bradycardia were thought to be the result of methyldigoxin and possibly associated with our perioperative management. Cardiology consult should have been obtained. We demonstrated that the FloTrac can be beneficial in diagnosing and managing cardiovascular instability and administration of dopamine in the anesthetic management of nonobstructive HCM patients.

Advances of cardiovascular MRI in hypertrophic cardiomyopathy

Hypertrophic cardiomyopathy (HCM) is a genetic disease characterized by abnormal myocardial hypertrophy, which can lead to a wide clinical spectrum, including sudden cardiac death and heart failure. Cardiac MRI has a significant role in establishing the diagnosis of HCM. In the three principal management issues related to HCM; testing of family members of affected individuals; assessing the risk of sudden cardiac death from lethal ventricular arrhythmias; and selection of appropriate treatments for left ventricular outflow obstruction, cardiac MRI has established or emerging roles.

Transmural and apicobasal gradients in repolarization contribute to T-wave genesis in human surface ECG

The cellular basis of the T-wave morphology of surface ECG remains controversial in clinical cardiology. We examined the effect of action potential duration (APD) distribution on T-wave morphology using a realistic model of the human ventricle and torso. We developed a finite-element model of the ventricle consisting of ∼26 million elements, including the conduction system, each implemented with the ion current model of cardiomyocytes. This model was embedded in a torso model with distinct organ structures to obtain the standard ECG leads. The APD distribution was changed in the transmural direction by locating the M cells in either the endocardial or epicardial region. We also introduced apicobasal gradients by modifying the ion channel parameters. Both the transmural gradient (with M cells on the endocardial side) and the apicobasal gradient produced positive T waves, although a very large gradient was required for the apicobasal gradient. By contrast, T waves obtained with the transmural gradient were highly symmetric and, therefore, did not represent the true physiological state. Only combination of the transmural and the moderate apicobasal gradients produced physiological T waves in surface ECG. Positive T waves in surface ECG mainly originated from the transmural distribution of APD with M cells on the endocardial side, although the apicobasal gradient was also required to attain the physiological waveform.

Endocardial and epicardial deformations in cardiac amyloidosis and hypertrophic cardiomyopathy

BACKGROUND

The aim of the present study was to analyze epicardial (EPI) and endocardial (ENDO) strain (S) in patients with transthyretin-related cardiac amyloidosis (TTR-CA) and hypertrophic cardiomyopathy (HCM) using echocardiography (TTE) with 2-dimensional feature tracking imaging (FTI).

METHODS AND RESULTS

Thirty-three subjects (11 with HCM, 11 with TTR-CA, and 11 healthy subjects as controls) with a New York Heart Association functional class ≤ II underwent conventional TTE and FTI. TTE was used for the evaluation of left ventricle (LV) wall thickness, mass, systolic and diastolic function. FTI was used for the evaluation of EPI and ENDO longitudinal, and circumferential, and radial S. LV wall thickness and mass were higher in both TTR-CA and HCM in comparison with controls (P < 0.001), but ejection fraction (EF) was similar among patients with TTR-CA, HCM and controls (63 ± 6%, 64 ± 6%, 61 ± 5%, respectively). ENDO and EPI longitudinal and circumferential S and radial S were significantly lower in HCM and TTR-CA when compared with controls (P < 0.01). No differences in EPI and ENDO longitudinal S, ENDO circumferential S and radial S were found between TTR-CA and HCM groups, while EPI circumferential S was significantly lower in the TTRCA group (6 ± 3.3%) than in the HCM group (8.1 ± 4.3%; P < 0.0001).

CONCLUSIONS

Longitudinal, circumferential and radial LV deformations are impaired in patients with TTR-CA and HCM with a preserved EF. Impairment of EPI circumferential strain is greater in TTR-CA than in HCM.

Cardiovascular screening of adolescent athletes

A preparticipation cardiovascular screening is recommended for all athletes with the aim of identifying conditions that increase the risk for adverse cardiac event, including sudden death. History and physical examination are the mainstay of cardiovascular screening of young athletes. The ability to identify athletes at risk, however, based on history and physical examination alone is low, and inclusion of an electrocardiogram as a screening tool has been suggested to improve the sensitivity of screening. This article provides an overview of key aspects of cardiovascular screening currently recommended in the United States for young athletes.

Pre-transplant Risk Factors for Chronic Renal Dysfunction After Pediatric Heart Transplantation: A 10-Year National Cohort Study

BACKGROUND

Chronic renal dysfunction may develop after pediatric heart transplantation (PHTx). We examined the incidence of end-stage renal disease (ESRD) and chronic renal insufficiency (CRI) after PHTx, the associated pre-transplant patient characteristics, and impact of renal disease on survival.

METHODS

Data sources included the Scientific Registry of Transplant Recipients, Centers for Medicare and Medicaid Services and the Social Security Death Master File. All PHTx recipients (age <18 years) in the USA from 1990 to 1999 who survived >1 year were included. ESRD was defined as long-term dialysis and/or kidney transplant. CRI was defined as creatinine >2.5 mg/dl, including those with ESRD. Relationships between pre-transplant characteristics and time to ESRD and CRI were analyzed using Cox proportional hazards models. The effect of renal disease on survival was analyzed using time-dependent Cox models.

RESULTS

During the mean follow-up of 7 years (range 1 to 14 years), 61 of 2,032 (3%) PHTxs developed ESRD. Ten-year actuarial risks for ESRD and CRI were 4.3% and 11.8%, respectively. In a multivariate analysis, significant risk factors for ESRD were: hypertrophic cardiomyopathy; African-American race; intensive care unit (ICU) stay or extracorporeal membrane oxygenation (ECMO) at time of transplant; and pre-transplant diabetes. Risk factors for CRI were: pre-transplant dialysis; hypertrophic cardiomyopathy; African-American race; and previous transplant. Adjusted risk of death in those who developed CRI was 9-fold higher than in those who did not (p < 0.0001).

CONCLUSIONS

After PHTx there is an increasing risk for CRI and ESRD over time. Recipients with the characteristics identified in this study may be at greater risk. Development of renal disease significantly increases the risk of post-transplant mortality.

Cardiac magnetic field map topology quantified by Kullback-Leibler entropy identifies patients with hypertrophic cardiomyopathy

Hypertrophic cardiomyopathy (HCM) is a common primary inherited cardiac muscle disorder, defined clinically by the presence of unexplained left ventricular hypertrophy. The detection of affected patients remains challenging. Genetic testing is limited because only in 50%-60% of all HCM diagnoses an underlying mutation can be found. Furthermore, the disease has a varied clinical course and outcome, with many patients having little or no discernible cardiovascular symptoms, whereas others develop profound exercise limitation and recurrent arrhythmias or sudden cardiac death. Therefore prospective screening of HCM family members is strongly recommended. According to the current guidelines this includes serial echocardiographic and electrocardiographic examinations. In this study we investigated the capability of cardiac magnetic field mapping (CMFM) to detect patients suffering from HCM. We introduce for the first time a combined diagnostic approach based on map topology quantification using Kullback-Leibler (KL) entropy and regional magnetic field strength parameters. The cardiac magnetic field was recorded over the anterior chest wall using a multichannel-LT-SQUID system. CMFM was calculated based on a regular 36 point grid. We analyzed CMFM in patients with confirmed diagnosis of HCM (HCM, n=33, 43.8+/-13 years, 13 women, 20 men), a control group of healthy subjects (NORMAL, n=57, 39.6+/-8.9 years; 22 women and 35 men), and patients with confirmed cardiac hypertrophy due to arterial hypertension (HYP, n=42, 49.7+/-7.9 years, 15 women and 27 men). A subgroup analysis was performed between HCM patients suffering from the obstructive (HOCM, n=19) and nonobstructive (HNCM, n=14) form of the disease. KL entropy based map topology quantification alone identified HCM patients with a sensitivity of 78.8% and specificity of 86.9% (overall classification rate 84.8%). The combination of the KL parameters with a regional field strength parameter improved the overall classification rate to 87.9% (sensitivity: 84.8%, specificity: 88.9%, area under ROC curve: 0.94). KL measures applied to discriminate between HOCM and HNCM patients showed a correct classification of 78.8%. The combination of one KL and one regional parameter again improved the overall classification rate to 97%. A preliminary prospective analysis in two HCM families showed the feasibility of this diagnostic approach with a correct diagnosis of all 22 screened family members (1 HOCM, 4 HNCM, 17 normal). In conclusion, Cardiac Magnetic Field Mapping including KL entropy based topology quantifications is a suitable tool for HCM screening.

Rare clinical presentation of nonobstructive hypertrophic cardiomyopathy: Apical aneurysm with thrombus

Hypertrophic cardiomyopathy patients rarely have left ventricular apical aneurysms without coronary artery disease and the pathophysiological processes responsible for apical wall thinning and aneurysm formation are not known exactly today. Here we present a rare nonobstructive hypertrophic cardiomyopathy case with an apical thrombotic aneurysm.

Resting ST-segment depression predicts exercise-induced subendocardial ischemia in patients with hypertrophic cardiomyopathy

BACKGROUND

Patients with hypertrophic cardiomyopathy (HCM) sometimes display characteristic electrocardiographic (ECG) findings at rest and develop subendocardial ischemia during exercise in the absence of coronary lesions. However, their relationship has not yet been fully clarified.

METHODS

Exercise Tc-99m-tetrofosmin myocardial scintigraphy was performed in 48 patients with non-obstructive HCM. We quantified transient left ventricular cavity dilation (LVCD) on exercise scintigrams, a parameter of subendocardial ischemia, and correlated the results with the ECG findings at rest and during exercise.

RESULTS

Transient LVCD occurred during exercise in 17 (35%) patients with HCM. Hemodynamic parameters during exercise did not differ between HCM patients with and without transient LVCD. Multiple logistic regression analysis showed that transient LVCD was significantly associated with ST-segment depression at rest (chi2=5.00, odds ratio=5.70, 95% confidence intervals 1.24-26.18, P=0.025) and a greater total number of leads with resting ST-segment depression (chi2=6.38, odds ratio=1.60, 95% confidence intervals 1.12-2.42, P=0.012). The degree of LVCD was correlated with the total number of leads with ST-segment depression at rest (P=0.002); the optimal cutoff for the diagnosis of transient LVCD was 3 with a sensitivity of 65%, a specificity of 90%, and an accuracy of 81%.

CONCLUSIONS

In patients with HCM, ST-segment depression at rest was accompanied by exercise-induced subendocardial perfusion abnormality as detected by myocardial scintigraphy. ST-segment depression at rest suggests that the subendocardium is predisposed to exertional ischemia.

Analysis of circulating apoptosis mediators and proinflammatory cytokines in patients with idiopathic hypertrophic cardiomyopathy: comparison between nonobstructive and dilated-phase hypertrophic cardiomyopathy

We examined the plasma levels of soluble Fas (sFas) or Fas ligand (sFas-L), tumor necrosis factor-alpha (TNF-alpha), and interleukin-6 (IL-6) in patients with idiopathic nonobstructive (HNCM) and dilated-phase (DHCM) hypertrophic cardiomyopathy. Patients with idiopathic hypertrophic cardiomyopathy (HCM) may deteriorate to DHCM and the pathogenesis is unknown. The levels of these plasma cytokines were measured by ELISA and echocardiography was performed in 38 HNCM and 11 DHCM patients, and 10 normal subjects. The follow-up period was three years. In HNCM, TNF-alpha (43.3 +/- 45.2 versus 16.9 +/- 4.3 pg/mL) and IL-6 (65.1 +/- 86.4 versus 4.0 +/- 2.1 pg/mL) were slightly higher compared to normal subjects and sFas (3.7 +/- 1.2 versus 2.1 +/- 0.7 ng/mL) increased significantly. sFas (3.9 +/- 1.8), TNF-alpha (79.3 +/- 72.4), and IL-6 (234.1 +/- 135.2) in DHCM were significantly increased and only IL-6 was significantly different from HNCM. sFas-L (0.18 +/- 0.08 versus 0.25 +/- 0.05 ng/mL) in HNCM was significantly decreased, and the decrease was marked in DHCM (0.05 +/- 0.02). In HNCM, TNF-alpha was negatively correlated with fractional shortening (r = -0.432, P = 0.0062) or positively with IL-6 (r = 0.665, P < 0.0001), while sFas-L was negatively correlated with IL-6 (r = -0.580, P < 0.0001). DHCM with high sFas had significantly higher cumulative incidences of worsening heart failure. The Fas/Fas-L system and proinflammatory cytokines may play an important role in the status of HCM and its progression to DHCM.

Hypertrophic Cardiomyopathy

Hypertrophic cardiomyopathy is a primary disorder of the myocardium characterised by disproportionate hypertrophy of the ventricular wall. It is the most common genetic cardiac disease with an incidence of 1 in 500 and it is diagnosed most commonly using transthoracic echocardiography. This review article discusses: the diagnosis of hypertrophic cardiomyopathy; the differential diagnoses; the characteristic histological signs found at postmortem and/or myectomy and the clinical symptoms and signs. Current recommendations for myectomy of first degree relatives, based on the ACC/ESC guidelines, are discussed as well as general management and then specific management for various subgroups and symptomatic patients.

α-Tropomyosin mutations Asp175Asn and Glu180Gly affect cardiac function in transgenic rats in different ways

To study the mechanisms by which missense mutations in α-tropomyosin cause familial hypertrophic cardiomyopathy, we generated transgenic rats overexpressing α-tropomyosin with one of two disease-causing mutations, Asp175Asn or Glu180Gly, and analyzed phenotypic changes at molecular, morphological, and physiological levels. The transgenic proteins were stably integrated into the sarcomere, as shown by immunohistochemistry using a human-specific anti-α-tropomyosin antibody, ARG1. In transgenic rats with either α-tropomyosin mutation, molecular markers of cardiac hypertrophy were induced. Ca2+sensitivity of cardiac skinned-fiber preparations from animals with mutation Asp175Asn, but not Glu180Gly, was decreased. Furthermore, elevated frequency and amplitude of spontaneous Ca2+waves were detected only in cardiomyocytes from animals with mutation Asp175Asn, suggesting an increase in intracellular Ca2+concentration compensating for the reduced Ca2+sensitivity of isometric force generation. Accordingly, in Langendorff-perfused heart preparations, myocardial contraction and relaxation were accelerated in animals with mutation Asp175Asn. The results allow us to propose a hypothesis of the pathogenetic changes caused by α-tropomyosin mutation Asp175Asn in familial hypertrophic cardiomyopathy on the basis of changes in Ca2+handling as a sensitive mechanism to compensate for alterations in sarcomeric structure.

Delayed contrast enhancement of MRI in hypertrophic cardiomyopathy

Fibrotic lesions in the myocardium exhibit delayed contrast enhancement (DCE) on MR images. On the other hand, plexiform fibrosis is observed in hypertrophic cardiomyopathy (HCM), indicating an association of this condition with the pathogenesis of heart failure and arrhythmia. To examine the occurrence and extent of DCE and its relation to cardiac function and arrhythmia in HCM, we studied 59 patients with HCM who had undergone MRI. The relationship of DCE to cardiac function and arrhythmia was further investigated. DCE occurred in 45 (76.3%) of the 59 patients with HCM, with a high frequency of localization in regions, where the right ventricle is attached. As for the relationship of DCE to cardiac function, a significant decrease (P=0.007) in cardiac function was observed in the group in which 4 or more segments exhibited DCE, compared with the group in which DCE was observed in 3 or less segments. Regarding the relationship of DCE to arrhythmia, both the occurrence of DCE and the extent of DCE were significantly larger (p<0.05, p=0.026, respectively) in the group with VT. These results indicate that DCE may save to identify severe cases of HCM on the basis of cardiac function, arrhythmia, and pathophysiological aspects.

Autoimmunity against the second extracellular loop of beta(1)-adrenergic receptors induces early afterdepolarization and decreases in K-channel density in rabbits

OBJECTIVES

We sought to define the electrophysiologic property of the rabbit heart associated with autoimmunity against the second extracellular loop of the beta(1)-adrenergic receptor.

BACKGROUND

Sudden death of patients with cardiomyopathy, probably due to lethal ventricular arrhythmias, can be predicted by the presence of autoantibodies against the second extracellular loop of the beta(1)-adrenergic receptor.

METHODS

Rabbits were immunized by repetitive subcutaneous administration of a synthetic peptide corresponding to the second extracellular loop of beta(1)-adrenergic receptors (beta group; n = 30) for a mean of 4.2 months. Control rabbits received only vehicle (control group; n = 30).

RESULTS

One of the rabbits in the beta group died suddenly during the observation period, but none of the control animals died. The prevalence of sustained ventricular tachycardia was significantly higher in the beta group (beta: 4 of 27 vs. control: 0 of 30), and a standard microelectrode experiment revealed prolongation of the action potential duration (APD) in the right ventricular papillary muscle (beta: 156 +/- 5 ms vs. control: 131 +/- 4 ms; p < 0.05). Early afterdepolarization (EAD) was observed in one rabbit in the beta group (1 of 26), but not in any animals in the control group (0 of 17). A dose of 100 nmol/l of E-4031 induced EAD in the beta group (10 of 10), but not in the control group, except for one rabbit (1 of 10). The whole-cell, patch-clamp experiment on left ventricular M cells showed significant decreases in transient outward current (I(to1)) (-43%) and slowly activated delayed rectifier current (I(Ks)) densities (-33%), whereas the inward-rectifying K current (I(K1)) and rapidly activated delayed rectifier current (I(Kr)) densities remained unchanged.

CONCLUSIONS

Long-term immunization against the second extracellular loop of the beta(1)-adrenergic receptor caused EAD and APD prolongation and decreased the K-channel density, suggesting that an arrhythmic substrate via autoimmune mechanisms is present in cardiomyopathic patients who have autoantibodies directed against the receptors.

Cardiac transplantation for hypertrophic cardiomyopathy: a valid therapeutic option

BACKGROUND

Hypertrophic cardiomyopathy is a rare indication for cardiac transplantation, with only anecdotal reports in the literature. Transplantation has been proposed to patients with hypertrophic cardiomyopathy who remained symptomatic despite optimal medical treatment or who progressed to congestive heart failure, and when conventional surgical correction was not or was no longer possible. In this report, we analyze the clinical results of cardiac transplantation in these patients.

METHODS

We retrospectively reviewed complete clinical data and prospectively gathered complete follow-up data for 14 patients who underwent orthotopic cardiac transplantation for hypertrophic cardiomyopathy at the Montreal Heart Institute and Ste-Justine Hospital between 1984 and 2001.

RESULTS

Ten male (71.4%, 5 adults and 5 children) and 4 female (28.6%, 2 adults and 2 children) patients underwent heart transplantation for hypertrophic cardiomyopathy. The median age of the recipients in the pediatric group was 13 years (range, 6-16) and was 40 years (range, 22-46) in the adult group. Median duration of follow-up was 9.5 years (mean, 8.8 +/- 4.8 years; range, 1-18) and was 100% complete. We found no operative mortality and found 2 late deaths related to coronary graft atherosclerosis. Long-term survival at 5, 10, and 15 years was 100%, 85%, and 64%, respectively. Freedom from acute rejection at 1, 5, and 10 years was 73%, 32%, and 9%, respectively. The remaining 11 survivors exhibit few symptoms and are currently in New York Heart Association Class I or II.

CONCLUSIONS

Cardiac transplantation is a valid therapeutic option for patients with symptomatic hypertrophic cardiomyopathy who do not respond to optimal medical management and who are not candidates for conventional surgical treatment. The long-term outcome is excellent in these patients.

Sudden cardiac death in the young in Sweden: electrocardiogram in relation to forensic diagnosis

OBJECTIVES

To study electrocardiogram (ECG) in relation to forensic diagnosis in young persons who suffered a sudden cardiac death (SCD) in Sweden during 1992-99.

DESIGN

A register study of a national database of forensic medicine in Sweden, selecting all cases of SCD 15-35 years of age. In this group, 12-lead ECGs and clinical data were searched for in military conscription and medical records. The ECGs were re-analysed and classified according to the Minnesota code criteria.

SETTING

The whole nation of Sweden.

SUBJECTS

Sudden cardiac death victims (66 individuals), 15-35 years of age, where it was possible to obtain an ECG recording.

RESULTS

We observed major or minor ECG abnormalities in 82% of the subjects. The most common changes were T wave abnormalities (35%), ST segment changes (32%) and conduction defects (20%). The ECGs were evaluated as pathological in 50% of the cases, more often in arrhythmogenic right ventricular cardiomyopathy (88%) and hypertrophic cardiomyopathy (82%). Cardiac-related symptoms were seen in 76% of the total group and there was a family history of a similar cardiac condition in 18%.

CONCLUSIONS

Pathological ECGs were common in young SCD victims, in spite of being taken many years before death. An ECG could help identify prospective victims of SCD, and should always be taken in cases with possible cardiac-related symptoms or a family history of SCD. The pathological ECGs were often found in connection with routine screening at military enlistment for men, which raises the question of a routine screening in the young, including women.

Hypertrophic cardiomyopathy: state-of-the-art review, with focus on the management of outflow obstruction

Significant advances in our understanding and management of hypertrophic cardiomyopathy have been made in the last decade, as the complex genetics and phenotype-genotype correlations that characterize the disease are gradually unravelled. The well-described clinical heterogeneity of hypertrophic cardiomyopathy is now understood to be based on profound genetic variability, with at least 10 genes and over 150 mutations implicated. Several new therapeutic tools have entered clinical practice. The implantable cardioverter-defibrillator is now strongly indicated in those at high risk of sudden arrhythmic death. Our ability to abort sudden death in this subgroup has placed added emphasis on risk stratification in newly diagnosed patients. New procedures have also been developed for the relief of outflow obstruction in patients with refractory symptoms and a significant subaortic outflow gradient. Although not as efficacious as the 'gold-standard' surgical myectomy-myotomy, dual-chamber pacemaker implantation can be of modest benefit in select patients. Percutaneous transluminal septal myocardial ablation is an emerging catheter-based procedure for the relief of left ventricular outflow obstruction. Long-term follow-up data are still awaited. However, intermediate-term results suggest equivalent efficacy to surgical myectomy-myotomy.

Dynamic left ventricular outflow obstruction: a reversible mechanical complication of acute myocardial infarction

Dynamic left ventricular outflow obstruction is a less well-known mechanical complication of acute myocardial infarction. Early diagnosis is important because initiation of proper management and avoidance of precipitating factors can lead to complete recovery. A patient is described who presented with acute myocardial infarction and in whom significant left ventricular outflow tract obstruction developed. Adequate therapy with beta blockers and calcium channel blockers led to complete resolution of the obstruction.

[Therapeutic approaches in symptomatic hypertrophic obstructive cardiomyopathy]

Hypertrophic cardiomyopathy is a complex and heterogeneous disease. Although most patients experience just a few symptoms, and have a good prognosis, there are others whose symptoms are severe and progressive, determined by different pathophysiological elements such as diastolic dysfunction, myocardial ischemia, arrhythmias and subaortic obstruction. Approximately 20-30% of hypertrophic cardiomyopathy patients develop an intraventricular dynamic gradient, which in some cases, is responsible for severe symptoms which are ameliorated once the obstruction is reduced. In many cases the symptoms can be controlled with medical treatment which includes betablockers, calcium-channel antagonists and dysopiramide, but some patients will still experience severe and refractory symptoms. This subgroup of patients, which represent approximately 5-10% of patients with hypertrophic cardiomyopathy, can be problematic from a management perspective. For many years, septal myectomy and/or mitral valve replacement offered the only effective alternative therapy for these patients. However, the high rates of morbidity and mortality associated with these procedures have necessitated the search for new and less invasive procedures such as ventricular pacing and percutaneous septal ablation. Although the initial results with sequential pacing were encouraging, further studies have suggested a significant placebo effect, which makes its application controversial. In the last 5 years selective embolization of the septal artery precipitating a localized myocardial infarction has been utilized to reduce the subaortic gradient. The potential indications and efficacy of these new forms of treatment, like ventricular pacing and percutaneous septal ablation, are presently under evaluation and are the main subject of this review. Medical treatment, with either beta-blockers, calcium channel antagonists or dysopiramide constitutes the first therapeutic step. Surgery, while alleviating the subaortic obstruction and reducing the intraventicular pressure and mitral insufficiency, produces important and long-lasting symptomatic and functional improvement in most of these patients, and it continues to be an important therapeutic alternative in these cases. If the first results with sequential pacemaker implants were encouraging, today it is alluded to an important placebo effect that causes its application to be controversial. In the last 5 years the path has been made in the creation of a septal infarction located through the embolization of the septal branches to reduce the gradient.

Hypertrophic cardiomyopathy with midventricular obstruction and apical aneurysm: a case report

A 71-year-old woman had hypertrophic cardiomyopathy associated with midventricular obstruction and an apical aneurysm in the left ventricle. She had had abnormal electrocardiograms for more than 30 years and for the past year had been suffering from occasional attacks of dizziness and low systemic blood pressure. Holter 24-h electrocardiographic monitoring revealed ventricular paroxysmal contractions (676/day) with nonsustained ventricular tachycardia. Doppler echocardiography revealed paradoxical jet flow from the apical aneurysm to the left ventricular outflow during early diastole. Magnetic resonance imaging depicted midventricular hypertrophy and a dyskinetic thin apical wall, which were confirmed by angiography. Coronary angiograms showed no narrowing of the major extramural coronary arteries, but there was compression of aberrant coronary arteries apparently feeding the hypertrophic portion of the left ventricular wall. Stress thallium-201 myocardial imaging showed a persistent severe defect in the left ventricular apex. A hemodynamic study revealed low cardiac output and an intraventricular pressure gradient (approximately 90 mmHg) between the left ventricular apical high-pressure chamber and the subaortic low-pressure chamber. The present case represents a rare combination of hypertrophic cardiomyopathy, midventricular obstruction, and an apical aneurysm in an elderly woman. Myocardial ischemia may have played an important role in the genesis of the apical aneurysm.

Impact of cardiac transplantation on molecular pathology of ET-1, VEGF-C, and mitochondrial metabolism and morphology in dilated versus ischemic cardiomyopathic patients

Little is known about the long-term impact of cardiac transplantation on activity and modifications of endothelin (ET)-1 system, vascular endothelial growth factor (VEGF), and mitochondrial metabolism and morphology in patients with ischemic cardiomyopathy (ICM) versus dilated cardiomyopathy (DCM). Messenger RNA (mRNA) expression levels of ET-1, endothelin converting enzyme (ECE)-1, VEGF-C, carnitine palmitoyltransferase (CPT)-1, and carnitine acetyltransferase (CARAT), as well as the number of normal, edematous, and degenerated mitochondria were assessed in left ventricular biopsies of 21 patients with DCM and 20 with ICM (New York Heart Association class III-IV) before and up to 3 months after cardiac transplantation. Cardiac samples of donated, nonfailing hearts served as controls (n=10). In cardiac biopsies of both ICM and DCM patients, ET-1, VEGF-C, CPT-1, and CARAT mRNA were up-regulated, whereas ECE-1 mRNA was down-regulated (P<0.05). Degenerated mitochondria had the highest number in both groups, followed by normal and edematous mitochondria. After cardiac transplantation, in ICM patients impaired gene expression levels decreased to, or below, normal levels, and the number of normal mitochondria increased (P<0.05). In implanted hearts of DCM patients, however, up-regulated ET-1 transcript levels persisted and the number of normal mitochondria decreased, whereas the number of degenerated mitochondria increased (P<0.05), and edematous mitochondria remained unchanged in number. These results show that cardiac transplantation corrects the impaired hemodynamic and echocardiographic parameters in both groups, whereas in DCM, the molecular pathology of ET-1 system and mitochondria persists. Therefore, it is more likely that these changes are the cause rather than a consequence of DCM.

Cardiac imaging

The emergence of noninvasive imaging techniques for the definitive diagnosis and monitoring of cardiovascular disease has greatly altered cardiac imaging in the past 25 years. The practice of cardiac imaging in 1975 was centered on conventional radiography and angiography, but, in the past 2 decades, noninvasive techniques have substantially replaced catheterization and angiography. The reliance on echocardiography for the evaluation of many cardiac diseases had a profoundly negative influence on the role of the radiologist in cardiac imaging, since the exercise of this modality has been a nearly exclusive province of the cardiologist. However, in the past decade, magnetic resonance imaging has been gradually assuming more importance in cardiovascular diagnosis; with this increase in importance, the role of the radiologist has been reactivated. In 1975, fellowship training in cardiac imaging was frequently combined with training in angiography. Now, training may be more effective by combining cardiac and pulmonary imaging in a thoracic imaging fellowship, but cross-training with an associated subspeciality will be influenced by priorities and personnel in various departments.

[Morphologic classification of hypertrophic cardiomyopathy with myocardial single photon emission tomography. Comparison with echocardiographic classification]

INTRODUCTION AND OBJECTIVES

The aim of this study was to compare different morphologic types of hypertrophic cardiomyopathy obtained by single photon emission tomography to those obtained by echocardiogram.

MATERIALS AND METHODS

In 76 (64%) out of 119 patients with hypertrophic cardiomyopathy the echocardiogram permitted an optimal visualization of all left ventricular segments in the short axis view and consequent classification to one of the six morphological types: type I (septal anterior hypertrophy), type II (septal anterior and septal posterior hypertrophy), type III (septal and antero-lateral hypertrophy), type IV (antero-lateral and/or septal posterior hypertrophy), type V (concentric hypertrophy) and type VI (apical hypertrophy). Without knowledge of echo data, two experienced observers included the short axis of single photon emission tomography images at rest (99mTc-tetrofosmin) to one of those types.

RESULTS

Global concordance between echocardiogram and single photon emission tomography was 75%. Type III was the most frequent both in echo (76%) and in single photon emission tomography (74%) and type III produced the majority of discrepancies. SPET identified 4 patients with a predominant septal and inferior hypertrophy, that did not correspond to any of the 6 types of echocardiographic classification and had been previously classified as type III by echo in 3 cases and as type V in 1 case.

CONCLUSIONS

There was agreement between echo and single photon emission tomography in the morphological classification of most of the patients (75%) with hypertrophic cardiomyopathy. Nevertheless, some discrepancies were observed for the type III echocardiogram.

Malalignment of the sarcomeric filaments in hypertrophic cardiomyopathy with cardiac myosin heavy chain gene mutation

OBJECTIVE

To investigate changes in the alignment of the sarcomeric filaments in hypertrophic cardiomyopathy and the effects of cardiac beta myosin heavy chain (beta-MHC) mutation on the sarcomeric ultrastructure.

DESIGN

A retrospective analysis.

PATIENTS

Endomyocardial biopsy samples were examined by transmission electron microscopy in seven patients with hypertrophic cardiomyopathy and beta-MHC mutation, six with hypertrophic cardiomyopathy but without the mutation, and five controls (with chest pain syndromes).

MAIN OUTCOME MEASURE

Alignment of the sarcomeric filaments and the distance between neighbouring thick myosin filaments.

RESULTS

In controls, cross sections of the sarcomere at the A band showed a highly organised orthohexagonal array with 6 thin actin filaments surrounding one thick myosin filament, whereas in hypertrophic cardiomyopathy the alignment of the sarcomeric filaments was sparse and disrupted. In hypertrophic cardiomyopathy with a mutation, the distance between neighbouring thick myosin filaments was greater than in controls (mean (SD) 45.3 (4.7) v 38.5 (3.5) nm, p < 0.05), and the variance of the distance was greater than in controls (8.0 (0.7) v 4.8 (1.0) nm, p < 0.001) or in patients with hypertrophic cardiomyopathy without a mutation (6.7 (0.6) nm, p < 0.05). In the latter, the variance of the distance was also greater than in the controls (p < 0.01). A significant correlation was found between the grade of the myocyte hypertrophy and the variance of the distance (r = 0.654; p < 0.01).

CONCLUSIONS

The alignment of the sarcomeric filaments is disrupted in hypertrophic cardiomyopathy, particularly when there is beta-MHC mutation.

Hypertrophic Cardiomyopathy

The degree of clinical expression of both obstructive and nonobstructive hypertrophic cardiomyopathy (HCM) is widely variable. Many patients with HCM are asymptomatic or minimally symptomatic. Most patients with mild or moderate HCM respond well to medical therapy, but medical therapy in patients with severe disease is only marginally beneficial. In some instances, medical therapy can even complicate management by producing significant conduction disturbances. Most symptomatic patients with a significant resting outflow tract gradient may respond to atrioventricular sequential electronic pacing. Most of these patients eventually become symptomatic again, however, because of progression of the disease process or other unknown factors. The outcome of myotomy-myectomy depends greatly on the surgeon's experience with this surgical procedure. In patients with very severe hypertrophy or evidence of left ventricular dilatation and systolic dysfunction, cardiac transplantation should be considered earlier than it would be on the basis of symptoms, functional capacity, and other factors.

Comparison of dual-chamber pacing versus septal myectomy for the treatment of patients with hypertrophic obstructive cardiomyopathy: a comparison of objective hemodynamic and exercise end points

OBJECTIVES

The purpose of this study was to compare the treatment effects of septal myectomy with dual-chamber pacing in patients with hypertrophic obstructive cardiomyopathy (HOCM).

BACKGROUND

The optimal treatment for symptomatic patients with drug-refractory HOCM is unknown. Both dual-chamber pacing and surgical myectomy may result in subjective symptom improvement. However, no direct comparisons with objective end points have been reported.

METHODS

Thirty-nine patients with symptomatic HOCM were analyzed in this concurrent cohort study. Twenty patients underwent surgical myectomy, and 19 received dual-chamber pacemakers based on patient preference. These patients had prospective baseline and follow-up evaluations including physician assessment, echocardiography and standardized metabolic treadmill exercise testing.

RESULTS

Baseline symptom status, left ventricular outflow tract gradients, exercise times and maximal oxygen consumption peak were similar between the two groups. Left ventricular outflow gradient was reduced from 76+/-57 to 9+/-17 mm Hg (p = 0.0001) after myectomy, and from 77+/-61 to 55+/-39 mm Hg (p = 0.07) after pacing (p = 0.02 for comparison with myectomy). Ninety percent of myectomy patients experienced symptomatic improvement as compared with 47% in the pacing group. Exercise duration increased significantly from 6.6+/-2.8 to 8.7+/-3.0 min (p = 0.0003) after myectomy compared with a change from 6.4+/-2.1 to 7.0+/-2.2 min (p = NS) in the pacing group. Maximal oxygen consumption increased from 19.4+/-6.4 to 22.2+/-6.5 ml/kg/min after myectomy (p = 0.004), whereas the pacing group did not experience any significant change (19.6+/-6.5 vs. 20.1+/-6.5 ml/kg/min, p = NS).

CONCLUSIONS

Surgical myectomy and dual-chamber pacing improve subjective measures of functional status in patients with symptomatic HOCM. In this nonrandomized study, myectomy offered greater reduction in left ventricular outflow tract gradients and larger improvements in objective measures of patient symptoms and functional status when compared with dual-chamber pacing.

Fixed left ventricular outflow tract obstruction in presumed hypertrophic obstructive cardiomyopathy: implications for therapy

BACKGROUND

A subset of patients presenting with a presumed diagnosis of hypertrophic obstructive cardiomyopathy (HOCM) have a fixed left ventricular outflow tract (LVOT) obstruction. Recognition of this pathophysiologic abnormality is important in choosing therapy.

METHODS

Of patients referred for treatment of HOCM, 4 had fixed LVOT obstruction. Clinical and echocardiographic data and surgical findings were reviewed.

RESULTS

In the 4 patients with clinical features consistent with HOCM or HOCM-like conditions, echocardiography showed fixed LVOT obstruction with an early-peaking LVOT Doppler signal or absence of severe systolic anterior motion of the mitral valve. The causes of fixed obstruction included accessory mitral tissue with associated fibrous ring (1 patient), fixed subaortic tunnel stenosis (2 patients), and a discreet subaortic ridge (1 patient). After surgical relief of the fixed LVOT obstruction, all patients had relief of the ventricular outflow tract gradient.

CONCLUSIONS

Not all patients with a presumed diagnosis of HOCM have isolated dynamic LVOT obstruction but may have isolated or additional fixed obstruction. Careful two-dimensional and Doppler echocardiography are needed to identify this subset of patients who are best treated surgically.

31P nuclear magnetic resonance spectroscopy: a noninvasive tool to monitor metabolic abnormalities in left ventricular hypertrophy in human

31p nuclear magnetic resonance (NMR) spectroscopy represents a unique instrument to noninvasively monitor myocardial metabolism in humans. The technique has been used to study the metabolism in myocardial hypertrophy in humans with hypertension, aortic stenosis, aortic incompetence, mitral regurgitation, and hypertrophic cardiomyopathy, as well as after maintenance dialysis or long-term physical exercise in elite cyclists. A primary aim is the determination of the phosphocreatine (PCr)/adenosine triphosphate (ATP) ratio, which reflects the energetic state of the myocardium. Recent investigations take advantage of proton decoupling in 31p NMR spectroscopy, which, besides the PCr/ATP ratio, also allows the determination of the inorganic phosphate/ PCr and the phosphomonoester/PCr ratios as additional indicators for alterations in myocardial metabolism. Abnormal myocardial metabolism was found in humans with aortic stenosis, mitral regurgitation, hypertrophic cardiomyopathy, and in patients who undergo maintenance dialysis. A trend toward a lower PCr/ATP ratio was reported in hypertension and aortic incompetence patients. Several studies have revealed a dependence of the metabolic abnormalities on the degree of heart failure, and one study claimed that a correlation with the extent of hypertrophy exists. No metabolic abnormalities were found in elite cyclists.

Predictors of sudden cardiac death in hypertrophic cardiomyopathy

Patients with hypertrophic cardiomyopathy (HC) die suddenly. Proposed risk factors for sudden cardiac death (SCD) in HC are youth, a family history of SCD, syncope, and ventricular tachycardia. Hemodynamic variables have not convincingly proved to be risk factors for SCD. Therefore, this study was designed to examine predictors of SCD in a large number of patients with HC during long-term follow-up periods. The relation of studied variables (clinical, electrocardiographic, echocardiographic, hemodynamic, and exercise test findings) to SCD in 309 patients with HC who were initially diagnosed during 1971 through 1994 (mean follow-up 9.4 years) was examined by multivariate analysis. SCD occurred in 28 patients. Independent predictors of SCD were a smaller difference between peak and rest systolic blood pressure during exercise testing (p=0.006), and higher left ventricular outflow tract pressure gradient at rest (p=0.003). Exercise-related SCD occurred in 8 patients and exercise-unrelated SCD in 20 patients (mean age 28 vs 47 years, p <0.05). Thus, patients of exercise-related SCD were younger and had smaller increases in systolic blood pressure during exercise testing, whereas patients with exercise-unrelated SCD were older and had higher left ventricular outflow tract pressure gradient.

Hypertrophic cardiomyopathy: presentation and pathophysiology

HCM is a heterogeneous disease with various clinical presentations. Recent advances in understanding the genetic abnormalities responsible for ventricular hypertrophy promise to improve our ability to diagnose this condition and to identify subgroups who are at the highest risk of cardiovascular mortality. Numerous difficulties remain in treating patients with HCM, including obtaining relief of symptoms and preventing SCD, but several new treatment options are currently being evaluated. In the future, randomized trials comparing the major treatment options (eg, pharmacologic therapy, myotomy/myectomy, mitral valve replacement, pacemaker implantation, and nonsurgical septal reduction) will be needed to provide guidance concerning the optimal treatment of patients with HCM.

The athlete's heart

We have provided an overview of the athlete's heart, focusing on the young athlete. Primary caretakers of athletes should know the major causes of exercise-related cardiac complications and sudden cardiac death and look for these conditions during preparticipation evaluations. We strongly suggest that coaches and other athletic personnel be required to learn basic life support measures such as cardiopulmonary resuscitation (CPR) and to update their skills on an annual basis. Such efforts will help prevent additional exercise-related cardiac deaths.

Dual-chamber pacing for hypertrophic cardiomyopathy: a randomized, double-blind, crossover trial

OBJECTIVES

In a double-blind, randomized, crossover trial we sought to evaluate the effect of dual-chamber pacing in patients with severe symptoms of hypertrophic obstructive cardiomyopathy.

BACKGROUND

Recently, several cohort trials showed that implantation of a dual-chamber pacemaker in patients with severely symptomatic hypertrophic obstructive cardiomyopathy can relieve symptoms and decrease the severity of the left ventricular outflow tract gradient. However, the outcome of dual-chamber pacing has not been compared with that of standard therapy in a randomized, double-blind trial.

METHODS

Twenty-one patients with severely symptomatic hypertrophic obstructive cardiomyopathy were entered into this trial after baseline studies consisting of Minnesota quality-of-life assessment, two-dimensional and Doppler echocardiography and cardiopulmonary exercise tests. Nineteen patients completed the protocol and underwent double-blind randomization to either DDD pacing for 3 months followed by backup AAI pacing for 3 months, or the same study arms in reverse order.

RESULTS

Left ventricular outflow tract gradient decreased significantly to 55 +/- 38 mm Hg after DDD pacing compared with the baseline gradient of 76 +/- 61 mm Hg (p < 0.05) and the gradient of 83 +/- 59 mm Hg after AAI pacing (p < 0.05). Quality-of-life score and exercise duration were significantly improved from the baseline state after the DDD arm but were not significantly different between the DDD arm and the backup AAI arm. Peak oxygen consumption did not significantly differ among the three periods. Overall, 63% of patients had symptomatic improvement during the DDD arm, but 42% also had symptomatic improvement during the AAI backup arm. In addition, 31% had no change and 5% had deterioration of symptoms during the DDD pacing arm.

CONCLUSIONS

Dual-chamber pacing may relieve symptoms and decrease gradient in patients with hypertrophic obstructive cardiomyopathy. In some patients, however, symptoms do not change or even become worse with dual-chamber pacing. Subjective symptomatic improvement can also occur from implantation of the pacemaker without its hemodynamic benefit, suggesting the role of a placebo effect. Long-term follow-up of a large number of patients in randomized trials is necessary before dual-chamber pacing can be recommended for all patients with severely symptomatic hypertrophic obstructive cardiomyopathy.

Dual-chamber pacing for cardiomyopathies: a 1996 clinical perspective

Implantation of a permanent pacemaker is an accepted mode of therapy for symptomatic bradyarrhythmias. Application of pacemaker technology for the treatment of cardiomyopathies has generated considerable interest and enthusiastic support in recent years. In both hypertrophic cardiomyopathy and dilated cardiomyopathy, dual-chamber pacing has been shown to decrease symptoms and improve hemodynamics; however, not all patients will benefit from dual-chamber pacing. Technical considerations must be acknowledged in order to obtain optimal benefit with dual-chamber pacing. In addition, other more accepted therapies are available for patients with symptomatic cardiomyopathies. The purposes of this article are to review critically the current literature on the use of dual-chamber pacemakers in patients with either hypertrophic or dilated cardiomyopathy and to provide a clinical perspective based on current knowledge.