Surgery for aortic stenosis in elderly patients. A study of surgical risk and predictive factors.

Background: Aortic stenosis is the most common valvular lesion occurring among elderly patients and has become extremely frequent because of changing demographics in industrialized countries. Surgical risk after the age of 70 has increased. The increasing older age of patients having surgery justifies an analysis of mortality predictive factors.

Four chamber pacing in dilated cardiomyopathy.

A 54-year-old man received a four chamber pacing system for severe congestive heart failure (NYHA functional Class IV). His ECG showed a left bundle branch block (200-msec QRS duration) with 200-msec PR interval, normal QRS axis, and 90-msec interatrial interval. An acute hemodynamic study with insertion of four temporary leads was performed prior to the implant, which demonstrated a significant increase in cardiac output and decrease of pulmonary capillary wedge pressure.

Antiarrhythmic agents in older patients. Current state of knowledge.

The treatment of ventricular arrhythmias in the elderly population is a challenging problem. Elderly patients are more predisposed to arrhythmias, are less responsive to antiarrhythmic agents and are more susceptible to the adverse effects of antiarrhythmic agents. Results from recent trial have altered the general approach to management of ventricular arrhythmias.

Strength-interval curves in canine myocardium at very short cycle lengths.

While ventricular electrophysiological properties have been intensively studied at normal heart rates, little is known about these properties at the very short cycle lengths (approximately 100 msec), which are present in ventricular fibrillation. We examined refractoriness in the right ventricles of six dogs at stimulation intervals of 80 to 300 msec. Starting at 300 msec, the basic (S1) cycle length was decremented by 10 msec each beat to 200, 150, or 125 msec.

Complete heart block complicating retrograde left ventricular catheterization: case report and review.

Complete heart block (CHB) following retrograde left ventricular catheterization is uncommon. We report a case of transient CHB in a patient with severe aortic stenosis and bifascicular block on the baseline surface electrocardiogram during retrograde left ventricular catheterization. The block resolved spontaneously without sequelae.

A fatal case of constrictive pericarditis due to a marked, selective pericardial accumulation of amyloid.

Distinguishing constrictive pericarditis from restrictive cardiomyopathy, usually due to amyloidosis, is a relatively frequent and difficult diagnostic problem. This report describes, for the first time, a patient with constrictive pericarditis caused by direct, extensive infiltration of the pericardium by amyloid, with only minimal amyloid in the myocardium, and a normal heart weight of 320 g. This patient demonstrates that amyloid may be predominantly deposited in the pericardium and actually cause constrictive pericarditis, as well as simulate its hemodynamic presentation by myocardial deposition.

[20 years of mitral valve replacement. Development of a patient profile and operative mortality].

Between 1971 and 1991, 1,179 mitral valve replacements (MVR) were carried out in 1,134 patients. The sex ratio was stable over this period (0.7 men/women) whereas the average age of the patients increased by 10 years (50 years in 1971, 61 years in 1991).

Epicardial mapping of ventricular defibrillation with monophasic and biphasic shocks in dogs.

To study the mechanism of defibrillation and the reason for the increased defibrillation efficacy of biphasic waveforms, the potential gradient in a 32 x 30-mm region of the right ventricle in 15 dogs was progressively lowered in four steps while a strong potential gradient field was maintained throughout the rest of the ventricular myocardium. The volume of right ventricle beneath the plaque was 10 +/- 2% of the total ventricular mass. A 10-msec monophasic (eight dogs) or 5/5-msec biphasic (seven dogs) truncated exponential shock 30% above the defibrillation threshold voltage was given via electrodes on the left ventricular apex and right atrium to create the strong potential gradient field.

[Arrhythmogenic cardiomyopathies of the right ventricle].

Arrhythmogenic cardiomyopathies of the right ventricle (ACRV) are defined by an association of left delayed type ventricular arrhythmias, ranging from apparently uncomplicated extrasystoles to more severe or even potentially lethal arrhythmias such as polymorphous VT and ventricular fibrillation, with an anatomical substrate consisting of adipose or fibro-adipose degeneration of the myocytes of the free wall of the ventricle, which may be either focal (in particular: apex, anterior surface of the infundibulum and the sub-tricuspid region), or more diffuse. It is then accompanied by RV systolic dysfunction with dilatation of the cavity. This apparently well defined clinico-pathological entity is in fact more complex, if only because of the existence of associated lesions of the left ventricle in 1/3 of cases.

Is polyurethane lead insulation still controversial?

A controversy arose some 10 years ago over the reliability of polyurethane lead insulation. On the basis of one of the longest standing and largest databanks worldwide, the authors compare the cumulative survival of several thousand polyurethane, standard silastic, and high-performance silastic electrodes as it pertains to the failure criterion described as insulation degradation. With the possible exception of the Medtronic 6972 (Medtronic, Inc.

High and low strength nonsynchronized shocks given during canine ventricular tachycardia.

Unlabelled: Cardioversion shocks given during ventricular tachycardia may cause ventricular fibrillation or acceleration of ventricular tachycardia, or arrest the tachycardia. A recently proposed theory may explain why the former two phenomena may occur. Briefly, this theory states that potential gradient shock fields of a critical strength delivered to tissue with a critical degree of refractoriness will cause circulating wave fronts of ventricular activation ("rotors") manifest as ventricular arrhythmia.

Failure of epinephrine to induce severe cardiac arrhythmia in rats with ventricular hypertrophy secondary to aortic pressure overload.

The arrhythmogenic action of epinephrine was studied in 3 groups of rats: 10 rats with mild constriction of the abdominal aorta (group H1), 10 rats with severe constriction (group H2), 10 sham-operated age-matched rats (group C). Blood pressure and ECG were recorded before, during and after 5 min. perfusion of increasing doses of epinephrine (1, 5, 10 and 25 micrograms.

[Immediate and long-term results of 790 mitral valve replacements].

A total of 790 patients underwent isolated (N = 520) or mitral valve replacement associated with a tricuspid valve procedure for lesions excluding post-myocardial infarction mitral regurgitation. The mean age was 54 years: the sex ratio was 1.9 +/- 1.

[Isolated myocardial infarction in the right ventricle: clinical and echocardiographic study].

The purpose of this study was, on the basis of 4 cases of isolated infarction of the right ventricle (RV), to describe the clinical profile of this disorder and compare the value of ultrasonography with other invasive methods of investigation (hemodynamic and kinetic angiocardiographic methods) in diagnosis and evaluation of the prognosis. In all cases the clinical situation was indicative: prolonged chest pain, slight enzymatic peak, downward shift of the ST segment in V3R and V4R. The diagnosis was rapidly confirmed by ultrasound in the face of the abnormal isolated segmental kinetics in the RV, associated with cavity dilatation and tricuspid incompetence.

Response of relatively refractory canine myocardium to monophasic and biphasic shocks.

Background: Certain biphasic waveforms defibrillate at lower energies than monophasic waveforms, although the mechanism is unknown.

Methods And Results: The relative ability of monophasic and biphasic shocks to stimulate partially refractory myocardium was compared because defibrillation is thought to involve stimulating relatively refractory myocardial tissue. Shocks of 25-125 V were given during regularly paced rhythm in 11 open-chest dogs.

Laser treatment of subfoveolar choroidal neovascular membranes.

We prospectively studied the safety and efficacy of subfoveolar laser treatment of choroidal neovascular membranes (CNVM) in 29 eyes. With one to four treatments, all CNVMs were successfully eradicated. Central visual acuity improved in 31% and stabilized in 69%.

Visual improvement after four laser treatments to foveola for choroidal neovascular membrane.

With the advent of new laser technology and refined treatment techniques, it is possible that visual morbidity may be reduced by the treatment of subfoveolar choroidal neovascular membranes. This case report from our prospective study series describes an eye that required four monochromatic green subfoveolar treatments for an active choroidal neovascular membrane, which was ultimately eradicated. Even though the foveola was treated four times, the visual acuity improved from 20/200 preoperatively to 20/40 postoperatively.

[New cardiac pacemakers].

Because of the extraordinary technological progress made over the past years in pulse generators, the objective and indications of definitive cardiac pacing have greatly changed. All the different advantages are aimed at mimicking the electrophysiological and mechanical conditions of normal heart function. We have seen the development of: DDD mode dual chamber pacemakers, which in cases of AV block recreate normal AV synchrony; single chamber rate-responsive units piloted by an external captor responding to the organism's metabolic needs (intra-corporal vibrations resulting from exercise, respiratory rate, minute ventilation, QT interval, central temperature, SV O2.

[Aneurysm of a saphenous vein aortocoronary shunt caused by fissure syndrome].

The authors report a new case of an aneurysm of a saphenous vein aorto-coronary shunt. The aneurysm manifested itself by a fissure syndrome in a man 48 years of age, 9 years after myocardial revascularization surgery. A chest X-ray revealed a right paracardiac opacity, and two-dimensional ultrasound picked up an expansive, hypoechoic mass.

[Benefits and limits of single chamber atrial pacing with adaptive rate].

Twelve patients with isolated symptomatic sinus node dysfunction or bradycardia-tachycardia syndrome with atrial chronotropic incompetence during exercise testing were managed by single chamber rate responsive atrial pacing (AAIR) when AV conduction was normal, or by a dual chamber DDDR pacemaker programmed in the AAIR mode when AV conduction was abnormal, and followed up for 12.5 +/- 9.8 months.

[Wolff-Parkinson-White syndrome in a case of acute rejection of cardiac transplantation].

A Wolff-Parkinson-White syndrome was observed during acute rejection in a patient who had undergone orthotopic cardiac transplantation. The sometimes intermittent nature of this syndrome could explain its postoperative appearance in this patient; the relationship with the episode of rejection is discussed.

Conduction disturbances caused by high current density electric fields.

During internal defibrillation, potential gradients greater than 100 V/cm occur near defibrillation electrodes. Such strong fields may cause deleterious effects, including arrhythmias. This study determined 1) the effects of such strong fields on the propagation of activation and 2) whether these effects were different for monophasic and biphasic shocks.