Intervention Versus Observation in Symptomatic Patients With Normal Flow Low Gradient Severe Aortic Stenosis

Objectives

The purpose of this study was to describe patients with severe symptomatic aortic stenosis with normal flow and low gradients and determine whether they benefit from intervention.

Valve Strain Quantitation in Normal Mitral Valves and Mitral Prolapse With Variable Degrees of Regurgitation

ObjectivesThe aim of this study was to quantitate patient-specific mitral valve (MV) strain in normal valves and in patients with mitral valve prolapse with and without significant mitral regurgitation (MR) and assess the determinants of MV strain.BackgroundFew data exist on MV deformation during systole in humans. Three-dimensional echocardiography allows for dynamic MV imaging, enabling digital modeling of MV function in health and disease.MethodsThree-dimensional transesophageal echocardiography was performed in 82 patients, 32 with normal MV and 50 with mitral valve prolapse (MVP): 12 with mild mitral regurgitation or less (MVP ? MR) and 38 with moderate MR or greater (MVP + MR). Three-dimensional MV models were generated, and the peak systolic strain of MV leaflets was computed on proprietary software.ResultsLeft ventricular ejection fraction was normal in all groups. MV annular dimensions were largest in MVP + MR (annular area: 13.8 ± 0.7 cm²) and comparable in MVP ? MR (10.6 ± 1 cm²) and normal valves (10.5 ± 0.3 cm²; analysis of variance: p < 0.001). Similarly, MV leaflet areas were largest in MVP + MR, particularly the posterior leaflet (8.7 ± 0.5 cm²); intermediate in MVP ? MR (6.5 ± 0.7 cm²); and smallest in normal valves (5.5 ± 0.2 cm²; p < 0.0001). Strain was overall highest in MVP + MR and lowest in normal valves. Patients with MVP ? MR had intermediate strain values that were higher than normal valves in the posterior leaflet (p = 0.001). On multivariable analysis, after adjustment for clinical and MV geometric parameters, leaflet thickness was the only parameter that was retained as being significantly correlated with mean MV strain (r = 0.34; p = 0.008).ConclusionsMVs that exhibit prolapse have higher strain compared to normal valves, particularly in the posterior leaflet. Although higher strain is observed with worsening MR and larger valves and annuli, mitral valve leaflet thickness—and, thus, underlying MV pathology—is the most significant independent determinant of valve deformation. Future studies are needed to assess the impact of MV strain determination on clinical outcome.     

Coronary microcirculation in essential hypertension: a quantitative myocardial contrast echocardiographic approach.

AIMS: The aims of the present study were: (a) to demonstrate whether quantitative myocardial contrast echocardiography can detect the increase in coronary flow induced by dipyridamole infusion vasodilation through the myocardial opacification due to the transit of microbubbles, both at rest and after dipyridamole induced vasodilation; (b) to explore the coronary microcirculatory function before and after dipyridamole in two different models: asymptomatic and relatively young hypertensive patients with a mild degree of left ventricular hypertrophy, and healthy controls. METHODS AND RESULTS: Two groups of strictly age-matched males were studied (case-control study): 10, relatively young and asymptomatic essential hypertensive patients with a mild degree of left ventricular hypertrophy with a normal left ventricular function, and 10 healthy controls. The main findings were: the microbubbles' appearance area was significantly lower in hypertensive patients than in controls (P<0.05) because of a significantly lower time to peak. The peak intensity at rest was higher in hypertensives than in controls (P<0.05); but the per cent increase after vasodilatory stimulus was significantly higher in controls (+71% in controls vs +31% in hypertensives; P<0.05). The microbubbles' disappearance area was comparable in both groups at rest; the per cent increase of this parameter after dipyridamole was significantly higher in controls (+124%) than in hypertensives (+90%) (P<0.05). The results achieved in this study documented that the coronary microcirculation in hypertensive patients presenting a mild degree of left ventricular hypertrophy, explored with quantitative myocardial contrast echocardiography, showed a different behaviour in comparison with controls, in the vasodilatory response to dipyridamole. CONCLUSION: The coronary microcirculation in hypertensives showed a reduced vasodilation capacity of the resistance arterioles under dipyridamole induced vasodilatation, and a possible impairment of the endothelium dependent vasodilation. This happened despite an increase in the left ventricular mass, where the relation between capillary bed distribution and hypertrophied myocardium (rarefaction phenomenon) is not completely respected.     

Usefulness of Transesophageal Echocardiography in Diagnosing Valve Leakage of Left Ventricular Assist Device

In this case report, we present the utility of transesophageal echocardiography in the detection of two uncommon complications of left ventricular assist devices: regurgitation of the bioprosthetic valve in the inflow conduit and a tear of a Dacron conduit with hematoma formation and compression of the right ventricular free wall.     

Left ventricular dysfunction in Rocky Mountain spotted fever

Rocky Mountain spotted fever is a serious infectious disease that continues to occur with increasing incidence in various areas of the United States. A high case-fatality ratio (11%) persists in spite of availability of adequate chemotherapeutic agents, and the cardiac involvement may play an important role in the final outcome of some cases. To assess the effect of the disease on left ventricular function 13 patients underwent M-mode echocardiographic examination on admission to a children's hospital. Increased left ventricular dimension was found in 3 patients and decreased left ventricular shortening fraction in 9. Diminished mean velocity of circumferential fiber shortening and increased left ventricular systolic time interval ratios were found in 8 patients and increased mitral valve E point to ventricular septal separation in 9. One patient died and biventricular dilatation with diffuse myocarditis was seen at autopsy. Repeat echo examination was available in 11 patients at follow-up (mean 5 months). Abnormal E mitral point to ventricular septal separation remained in 4 patients and decreased left ventricular shortening fraction in 2. The long-term prognosis for this group is unknown. Myocardial involvement is frequently present in Rocky Mountain spotted fever; close monitoring and aggressive therapeutic approach are essential if the high case-fatality ratio is to be reduced.     

Long-term survival of a patient with left ventricular free wall rupture without surgical repair

This report describes the case of a patient who developed postinfarction left ventricular free wall rupture and cardiac tamponade. He was managed conservatively, made a successful recovery, and is alive and asymptomatic 10 months after the index episode. Only 17 cases in which the patients survived subacute rupture of the ventricular free wall over the long term without surgical repair have been reported in the literature.     

Implantable cardioverter-defibrillators (ICDs) 1989: How close are we to the ideal device?

Major technical advances over the last few years have led to significant improvements in implantable cardioverter-defibrillators. Tachycardias can be detected using a number of criteria which include rate, rate of onset, duration, and stability of tachycardia. A number of target tachyarrhythmias can be distinguished in the same patient and differentiated from sinus or other benign tachycardias. Different tachycardias can then be treated with different electrical therapies. Therapies now incorporated in the latest generation of implantable devices include comprehensive antitachycardia pacing techniques, low-energy cardioversion and high-energy cardioversion-defibrillation. Bradycardia support pacing is also incorporated. Improvements in the electrodes used for sensing tachycardia and delivering therapy have resulted in the first implants of devices without the need for thoracotomy. Improvements in capacitor technology have resulted in a gradual reduction in the size of devices in spite of their increasing sophistication. Further research is needed to evaluate different shock charges and waveforms. Tachycardia prevention by implanted devices is also a field of much current research. Thus, though not yet "ideal," the latest generation of implantable cardioverter-defibrillators represents an important therapeutic option in the treatment of ventricular tachyarrhythmias.     

Influence of the force--frequency relationship on haemodynamics and left ventricular function in patients with non-failing hearts and in patients with dilated cardiomyopathy

In isolated human myocardium it was shown that a positive force-frequencyrelationship occurs in non-failing myocardium; however, theforce-frequency relationship was found to be inverse in myocardiumfrom failing human hearts. In order to investigate the clinicalrelevance of these experimental findings, the influence of heartrate changes on haemodynamics and left ventricular functionwas studied in eight patients without heart failure and in ninewith failing dilated cardiomyopathy (NYHA II–III). Rightventricular pacing was performed at a rate slightly above sinusrate and at 100, 120 and 140 beats. min^–1 Haemodynamicparameters were obtained by right heart catheterization andby high-fidelity left ventricular pressure measurements. Leftventricular angiography was performed at basal pacing rate andat 100 and 140 beats. min^–1 With increasing heart rate,cardiac index increased in patients with normal left ventricularfunction from 2·9 ± 0·2 to 3·5 ±0·21. min^–1. m^–2 (P<0·01) and decreasedcontinuously in patients with dilated cardiornyopathy from 2·6± 0·1 to 2·2 ± 0·11. min^–1. m^–2 (P<0·05). With increasing heart rate,the maximum rate of left ventricular pressure rise increasedin non-failing hearts from 1388 ± 86 to 1671 ±88 mmHg. s^–1 (P<0·01) and did not change infailing hearts. Ejection fraction decreased from 27 ± 3% to 19 ±2% in patients with dilated cardiomyopathy (P<0·05)when the pacing rate was changed from 84 ± 2 beats. min^–1to 140 beats. min^–1, which was associated with a significantlyincrease in end-systolic volume without significantly changesin end-diastolic volume. In patients with normal left ventricularfunction, when the pacing rate was changed from 85 ±3 beats. min^–1 to 140 beats. min^–1, end-diastolicvolume decreased significantly by 13%, whereas left ventricularend-systolic volume and ejection fraction did not significantlychange. Left ventricular systolic and end-diastolic pressuresdid not significantly change with pacing tachycardia in eithergroup. The frequency-related changes in left ventricular volumesand pressures indicate that the differrent haemodynamic effectsof pacing tachycardia in both groups of patients result predominantlyfrom frequency effects on myocardial function and not from frequencyeffects on preload or afterload. These data indicate that recentexperimental findings of positive force-frequency effects innon-failing and negative force-frequency effects in failinghuman myocardium are relevant for the intact heart.     

Clinical significance and characteristics of exercise-induced ventricular tachycardia

Forty-seven patients (0.08%) from a total of 5,730 consecutive patients undergoing treadmill stress tests developed one or more episodes of ventricular tachycardia. Forty patients had heart disease, coronary artery disease being the leading cause. Rest ECG was normal in 12 patients and showed long QT (>440 msec) in 16 patients. Ventricular tachycardia was brief and self-terminating, requiring D/C cardloverston In only one patient. “Exertional hypotension” preceded ventricular tachycardia In 16 of 34 patients. There was poor correlation (r=0.16) between the rate of ventricular tachycardia (VT) and the underlying heart rate. Only four episodes of VT were Initiated by R on T premature ventricular beats. In summary, exercise-Induced ventricular tachycardia 1) Is a rare complication of treadmill stress test and occurs In patients with heart disease; 2) is frequently preceded by “exertional hypotension;” and 3) Is not related to the R on T phenomenon. The high incidence of prolonged QT may indicate a role for the autonomic nervous system in its pathogenesis.     

不同部位组合起搏对充血性心力衰竭患者急性血流动力学影响的研究

观察右房左室起搏对充血性心力衰竭 (CHF)患者急性血流动力学的影响。 8例心功能II～IV级CHF患者 ,分别置入右房、右室和左室电极 (经冠状静脉窦 ) ,行不同部位组合起搏的急性血流动力学研究 ,其中 6例获得成功。使用Bitronic公司生产的双腔起搏分析仪 (ERA30 0 )分别行单纯右室心尖部 (RVA)、右房右室 (RA +RV)、右房左室 (RA +LV)、右房双室 (RA +BiV)起搏 ,同时用二维超声心动图测定上述四种起搏状况下的血流动力学参数 ,并进行比较。结果 :右房左室起搏和右房双室起搏血流动力学参数两者间无显著差异 ,但比单纯右室心尖部起搏和右房右室起搏有所改善。结论 :右房左室起搏似可使更多的CHF患者在得益于起搏治疗的同时明显降低医疗费用。