Clinical and Doppler echocardiographic follow-up after percutaneous balloon valvuloplasty for aortic valve stenosis

Percutaneous balloon valvuloplasty has been shown to increase the aortic orifice area and to improve clinical symptoms. However, there are only few data concerning long-term results after balloon valvuloplasty. In this study, 36 patients (11 men, 25 women, mean age 75 +/- 8 years) were followed after balloon valvuloplasty for a period of up to 18 months by means of clinical parameters and repeated Doppler echocardiographic measurements after 1, 3, 6, 12 and 18 months. Invasive measurements revealed a decrease of the systolic peak gradient from 78 +/- 24 to 38 +/- 13 mm Hg (p less than 0.001), and an increase in the aortic orifice area from 0.58 +/- 0.23 to 0.93 +/- 0.2 cm2 (p less than 0.001). The Doppler echocardiographic approach revealed that the maximal instantaneous gradient decreased from 96 +/- 26 to 67 +/- 22 mm Hg (p less than 0.001). The aortic orifice area increased from 0.49 +/- 0.16 to 0.73 +/- 0.21 cm2 (p less than 0.001). Three patients (8%) died in the hospital. After hospital discharge, 16 patients (44%) died and 8 patients (22%) underwent successful aortic valve replacement after a mean follow-up of 8 +/- 6 months. Nine patients (25%) were alive after a follow-up period of 18 months. Seven of these (19%) remained clinically improved. During follow-up, the Doppler echocardiographic results revealed a continuous trend toward the preprocedural severity of the aortic valve stenosis. Progression of restenosis assessed by Doppler echocardiographic measurements was accelerated in the group of patients who subsequently died or underwent repeat balloon valvuloplasty or aortic valve replacement.

[Prolongation of hospital stay by nosocomial pneumonia and wound infection]

From June 1988 to September 1989, a prospective survey comprising a total of 1183 patients in a university hospital was carried out to ascertain the additional length of stay in intensive care units because of nosocomial pneumonia associated with artificial ventilation (418 patients, 296 men, 122 women, mean age 48.8 +/- 21 years, ventilated for more than 24 h) or by postoperative wound infections (765 patients, 501 men, 264 women, mean age 60 +/- 11 years, after operations on the large bowel, heart or biliary tract). Each patient with a nosocomial infection was matched against a variable number of control patients (for cases of pneumonia a maximum of 6, for wound infections a maximum of 10) without nosocomial infection. Pneumonia developed in 100 (23.9%) of artificially ventilated patients, and 46 of these patients together with 101 controls were entered into the matching procedure. 24 patients with pneumonia had to be excluded from analysis because no controls could be found for them, and also 30 patients who died while in the intensive care unit. 49 (6.4%) of the surgical patients contracted postoperative wound infections. 43 of them, together with 210 controls, were entered into the matching procedure. Among patients with pneumonia the average additional duration of stay was 11.5 days, and among patients with post-operative wound infections it was 13.9 days. The results confirm that nosocomial infections contribute substantially to prolongation of hospital stay and hence to the costs.

Modulation of coronary vasomotor tone in humans. Progressive endothelial dysfunction with different early stages of coronary atherosclerosis

The endothelium plays a critical role in the control of vasomotor tone by the release of vasoactive substances. Because endothelial injury or dysfunction is considered important very early in atherogenesis, we hypothesized that abnormal endothelial function precedes the angiographic detection of coronary atherosclerosis in the human coronary circulation. The coronary vasomotor responses to three different endothelium-mediated stimuli (intracoronary infusion of acetylcholine 10(-8) to 10(-6) M, increase in blood flow to induce flow-dependent dilation, and sympathetic stimulation by cold pressor testing) were assessed by quantitative angiography and subselective intracoronary Doppler flow velocity measurements within the left anterior descending coronary artery in 38 patients. All three stimuli elicited epicardial artery dilation in all 11 patients with smooth coronary arteries and absence of risk factors for coronary artery disease (group 1). All nine patients with smooth coronary arteries but with hypercholesterolemia (group 2) demonstrated a selective impairment in endothelial function with vasoconstriction (35 +/- 12.7% decrease in mean luminal area) in response to acetylcholine but showed a preserved flow-dependent dilation (15.5 +/- 4.4% increase in mean luminal area) and vasodilation in response to cold pressor testing (14.2 +/- 4.6% increase in mean luminal area). In all nine patients with an angiographically defined smooth coronary artery segment but with evidence of atherosclerosis elsewhere in the coronary system (group 3), both acetylcholine and cold pressor testing induced vasoconstriction (26.2 +/- 8.7% and 18.7 +/- 7.9% decrease in mean luminal area, respectively), whereas flow-dependent dilation was preserved (20.4 +/- 8.7% increase in mean luminal area). In the nine patients with angiographic evidence of wall irregularities (group 4), flow-dependent dilation was also abolished and vasoconstriction occurred in response to acetylcholine and cold pressor testing (34.5 +/- 10.7% and 19.9 +/- 6.3% decrease in mean luminal area, respectively). All coronary artery segments dilated in response to nitroglycerin, suggesting preserved function of vascular smooth muscle. Despite similar reductions in coronary vascular resistance in response to the smooth muscle relaxant papaverin, patients with hypercholesterolemia demonstrated a selective impairment of vasodilation of the resistance vasculature in response to acetylcholine (p less than 0.05 versus groups 1, 3, and 4). Thus, there is a progressive impairment of endothelial vasoactive functioning in coronary arteries of patients with different early stages of atherosclerosis, beginning with a selective endothelial dysfunction in angiographically defined normal arteries in patients with hypercholesterolemia and progressively worsening to a complete loss of endothelium-mediated vasodilation in angiographically defined atherosclerotic coronary arteries.(ABSTRACT TRUNCATED AT 400 WORDS)

Cilazapril in congestive heart failure. A pilot study

The haemodynamic effects of a single dose of cilazapril 2.5 or 5 mg were studied in 33 patients with stable chronic congestive heart failure who were receiving digitalis and diuretics. Subsequently, a double-blind comparison of the haemodynamic and clinical effects of 3 months' treatment with cilazapril 1.25 to 5 mg daily or placebo in 24 evaluable patients revealed that the acute haemodynamic improvement produced by a single dose of cilazapril was maintained in patients receiving repeated administration of the drug, but not in those randomly allocated the placebo. Acute cilazapril significantly decreased mean arterial pressure, systemic vascular resistance, pulmonary capillary wedge pressure, pulmonary artery pressure and right atrial pressure, while cardiac index and stroke volume index increased at rest and during submaximal exercise. After 3 months' treatment 11 of 13 cilazapril recipients improved their New York Heart Association (NYHA) class compared with 2 of 11 patients treated with placebo. This functional improvement was paralleled by a patient-perceived improvement in general well-being.

Assessment of coronary vasomotor tone in humans

The assessment of endothelium-mediated modulation of coronary vasomotor tone in the intact human circulation under physiologic conditions requires very precise determination of both epicardial artery diameters, reflecting effects within the conduit vessels, as well as coronary blood flow, reflecting effects within the resistance vasculature during cardiac catheterization. In the present report, the accuracy and limitations of quantitative approaches to assess arterial dimensions from coronary angiograms are discussed. Using state-of-the-art image-processing techniques and x-ray imaging, epicardial artery diameter changes within the range of 8-10% can be reliably detected by quantitative coronary angiography. In addition, advances in interventional techniques do provide a means to selectively assess intracoronary blood-flow velocities using intracoronary Doppler catheters. Combining epicardial artery diameter measurements and intracoronary blood-flow velocity parameters allows for a reasonably accurate instantaneous estimate of coronary arterial blood flow. The advantages and limitations of the intracoronary Doppler technique compared to other techniques are discussed.

Mechanisms involved in the response to prolonged infusion of atrial natriuretic factor in patients with chronic heart failure

We examined the mechanisms involved in the cardiovascular and renal response to prolonged infusion of atrial natriuretic factor (ANF) in patients with chronic heart failure. ANF infusion was titrated to produce a 30% decrease in pulmonary capillary wedge pressure or a 20% increase in cardiac output, and this dose (average, 75 +/- 4 ng/kg/min) was then administered for 20 hours. The short-term response to ANF included significant reductions in central filling pressures, increases in cardiac output, modest increases in diuresis and glomerular filtration rates, significant reduction in plasma aldosterone levels, and a 3.6-fold increase in plasma cyclic GMP levels. During prolonged infusion, plasma cGMP levels and cardiac output gradually returned to baseline. Similarly, the initially increased diuretic effects were completely abolished during prolonged ANF infusion, although plasma alpha-hANF levels remained consistently elevated above baseline values (control, 198 +/- 38; titration, 2,760 +/- 596; 20 hours, 3,499 +/- 659 pg/ml). Four hours after beginning the ANF infusion, marked increases in hematocrit levels were noted (42.5 +/- 1.0% versus 45.3 +/- 1.4%, control and infusion, respectively, p less than 0.05); during this time, no change in total plasma protein concentration occurred, indicating extravascular shift of fluid and plasma proteins. No evidence was noted for activation of vasoconstrictor hormones during prolonged ANF infusion, although mean arterial pressure was significantly reduced throughout the infusion period. Plasma pro-ANF (31-67) levels, determined as a marker for endogenous ANF secretion, were significantly suppressed as were the reductions of central filling pressures. After ANF discontinuation, heart rate and pulmonary capillary wedge pressure increased significantly above baseline values without evidence for sympathetic stimulation. We conclude that 1) prolonged infusion of ANF causes only transient increases in plasma cGMP levels but a sustained reduction of the cardiac release of ANF and that 2) the beneficial hemodynamic effects of ANF, that is, unloading of the ventricles, may be associated with or, in part, may be secondary to a shift of plasma constituents into the extravascular space. The latter may limit the therapeutic potential of ANF for long-term treatment.

Echocardiographic evaluation of patients with clinically suspected arterial emboli

153 patients (mean age 42 years, range 16-60) who had arterial embolic events were examined prospectively by transthoracic and transoesophageal echocardiography. Patients older than 60 years and those with evidence of extracranial carotid artery occlusive disease were excluded. 84 patients had a cerebral ischaemic event, 50 patients had embolic events in an abdominal organ or limb, and 19 patients had acute retinal ischaemia. The transthoracic echocardiographic examination was normal in 92 patients (60%), whereas only 65 patients (42%) had normal findings after both transthoracic and transoesophageal examination (p less than 0.005). Intracardiac masses, including valvular vegetations, were found in 39 patients (25%), including 27% of patients with cerebral embolism and 32% of these with peripheral embolism, but in none of the patients with retinal ischaemia (p less than 0.001). 47 patients (31%) had valvular disease, 10 (7%) had wall motion abnormalities, 23 (15%) had abnormalities of the interatrial septum, and 9 patients (6%) had diseases of the thoracic aorta. Cardiovascular abnormalities were frequently found by echocardiography in patients with arterial emboli. The transesophageal technique significantly increased the chance of detecting such abnormalities, especially intracardiac masses.

Treatment with diltiazem preoperatively in open heart surgery for myocardial protection: experimental studies in dogs with chronic healed myocardial infarction

Calcium antagonists have become important in open heart surgery because of their effects on myocardial protection and cardioplegia. We evaluated the effect of pretreatment with the calcium antagonist diltiazem for myocardial protection in dogs with experimentally induced, chronic, healed myocardial infarction in a double-blind randomized study. One group consisted of 5 dogs treated with diltiazem (10 mg/kg bodyweight) for 7 days preoperatively, while a second group of 4 dogs were treated with placebo. All animals then underwent hypothermic, ischemic cardiac arrest (90 min) with extracorporeal circulation (ECC), followed by 30 min of reperfusion. Hemodynamic parameters were measured before and after ECC. An EKG was recorded during the entire procedure. The myocardium was studied by light microscopy for fresh necroses. The old, experimentally induced infarction scars were quantified by a new method that was developed for planimetry of the histological specimens. The diltiazem group compared with the placebo group showed myocardial cell necroses to a smaller extent. The hemodynamic studies supported the contention that diltiazem given preoperatively has a myocardial protective effect. These results encourage further studies on the use of diltiazem preoperatively for myocardial protection.

[The thrombolytic treatment of acute and subacute recurrent pulmonary embolism with recombinant tissue plasminogen activator]

Thrombolytic treatment with recombinant tissue plasminogen activator (rt-PA) at a dosage of 40-150 mg was given to five patients with acute and five with recurrent pulmonary emboli (three women and seven men; mean age 54 [30-78] years). Mean pulmonary artery pressure fell from 29 +/- 7 mm Hg before to 20 +/- 5 mm Hg after treatment (P = 0.001), and in recurrent emboli from 47 +/- 19 to 18 +/- 10 mm Hg (P = 0.01). Pulmonary vascular resistance fell from 546 +/- 262 to 318 +/- 116 dyn.s.cm-5 (P = 0.02) in the former group and from 993 +/- 583 to 377 +/- 438 dyn.s.cm-5 (P = 0.01) in the latter. Pulmonary arteriograms were assessed using the Miller index. This indicated a drop from an average of 23 points before to an average of 10.5 points after treatment. Mild bleedings occurred in all patients, but in two it was severe enough to require discontinuation of treatment. These results demonstrate that rt-PA is highly effective as a thrombolytic agent in acute and in subacute recurrent pulmonary embolism.

Detection of traumatic myocardial injury by means of simultaneous Tl-201/Tc-99m pyrophosphate tomography--report of three cases

Trauma to the chest can result in cardiac damage, which may be missed by clinical examination because of associated injuries. Routinely performed non-invasive tests may also be non-diagnostic. Tc-99m pyrophosphate (PPi) tomography, in this study combined with Tl-201, is a promising addition to non-invasive evaluation. In three patients with cardiac injury, this technique successfully detected and localized myocardial necrosis.

Coronary reperfusion studies with pro-urokinase in acute myocardial infarction: evidence for synergism of low dose urokinase

Pro-urokinase is a single chain precursor of two chain urokinase, which has been shown to induce fibrin-selective plasminogen activation. In the present study, thrombolytic efficacy of 9 million U of glycosylated pro-urokinase administered intravenously was compared with that of a combined regimen utilizing 4.5 million U of pro-urokinase and 0.2 million U of urokinase. Seventy-five patients with a first myocardial infarction were randomized to receive high dose pro-urokinase (n = 40, group A) or the combination therapy (n = 35, group B). Reperfusion of the infarct-related artery was assessed by repeat coronary angiography. Thrombolysis in Myocardial Infarction trial (TIMI) grade II or III reperfusion was achieved in 73% of group A patients compared with 66% of group B patients (p = NS). A trend toward faster reopening of the infarct-related artery was observed in patients in group B. Coronary artery reocclusion occurred in 5 (10%) of 49 patients in whom angiography was repeated within 36 h after the start of therapy. Clot-selective thrombolysis was indicated by a minimal fibrinogen decline (15% and 13%, respectively, in groups A and B). Alpha 2-antiplasmin levels, however, decreased more rapidly in patients in group B (p less than 0.05). This finding and the equivalent reperfusion rate in the combined treatment group strongly suggest synergistic interaction between these two thrombolytic agents. In summary, the high incidence of reperfusion, the low rate of early reocclusion and the paucity of side effects, particularly with regard to bleeding complications, indicate that pro-urokinase possesses the characteristics of an ideal thrombolytic agent.

[Transesophageal echocardiography in the assessment of the severity of aortic valve stenosis]

The aortic valve orifice area was measured in 95 patients with valvular aortic stenosis by means of transthoracic and transesophageal echocardiography. These results were compared to invasively determined measurements. The aortic-valve orifice area could be measured by transesophageal echocardiography in 87 patients (92%), and in 13 patients (14%) by the transthoracic approach. A comparison of the valve-orifice area determined by transthoracic and transesophageal echocardiography revealed a correlation coefficient of r = 0.91. There was also a good agreement when the aortic-valve orifice area determined by transesophageal echocardiography was compared to the invasive findings (r = 0.82; p less than 0.001). The morphology of the aortic valve could be better delineated with the transesophageal approach.

Acute myocardial infarction delineated by noninvasive thallium-201/technetium-99m pyrophosphate tomography

The purpose of this study was to validate different scintigraphic approaches for assessing acute myocardial infarctions. 201Tl, 99Tcm pyrophosphate (PPi) and combined 201Tl/99Tcm PPi tomograms were evaluated in 115 consecutive patients, in 85 of whom clinical examination revealed acute myocardial infarction. The overall sensitivity and specificity for infarct detection was 80% versus 56% for 201Tl alone, 61% versus 97% for 99Tcm PPi alone, and 100% each for the combined 201Tl/99Tcm PPi imaging. The sensitivity for nontransmural infarcts was 57% for 201Tl, 37% for 99Tcm PPi and 100% for combined imaging. The overlay of 201Tl and 99Tcm PPi images increases the observer's confidence in the diagnosis and provides better localization of the infarction. 201Tl alone could localize the infarction in 80%, 99Tcm PPi alone in 49% and 201Tl/99Tcm PPi in 100% of the cases. ECG and 201Tl/99Tcm PPi tomography concurred upon infarct localization in 98% of the patients. Based on the 201Tl/99Tcm accumulation pattern, 94% of the Q-wave infarctions were judged to be transmural and 83% of the non-Q-wave infarctions were judged to be nontransmural. It is concluded that combined 201Tl/99Tcm PPi tomography is highly accurate for determining the presence and location of acute myocardial infarction. This technique appears to be superior to studies where only one radioisotope is used.

[Effect of atrial natriuretic factor on coronary vascular tone]

To test whether atrial natriuretic factor (ANF) may be involved in the modulation of coronary vasomotor tone, ANF was injected into angiographically normal left coronary arteries. Measurement of epicardial diameters of the circumflex (Cx) and left anterior descending artery (LAD) were made from biplane angiograms by an automatic contour-detection system. Bolus injection of ANF (0.07 micrograms/kg, diluted in 1 ml 0.9% NaCl, n = 7) increased diameter of proximal segments of LAD (11 +/- 4%) and Cx (10 +/- 4%) (p less than 0.02 each vs control) without altering heart rate and mean arterial pressure (MAP). Intracoronary nitroglycerin (NTG, 0.3 mg) increased diameters of identical LAD and Cx segments by 18 +/- 3% and 20 +/- 4%. Intracoronary ANF infusion (0.02 micrograms/kg/min over 5 min, followed by 0.1 micrograms/kg/min, n = 10) exerted dose-dependent increases in diameters of LAD and Cx (low dose: + 5 +/- 2%, p less than 0.05 vs control; high dose: + 13 +/- 3%, p less than 0.01 vs control). ANF-infusion increased arterial plasma ANF levels from 280 +/- 80 pg/ml during control to 894 +/- 82 pg/ml (low dose; + 614 pg/ml vs control) and to 2290 +/- 228 pg/ml (high dose). Severe ischemia in four patients undergoing angioplasty exerted substantial increase in arterial ANF levels (160 +/- 60 to 608 +/- 111 pg/ml; + 448 pg/ml vs control), similar to the increase elicited by low dose ANF infusion in man.(ABSTRACT TRUNCATED AT 250 WORDS)

Lidocaine in the early phase of acute myocardial infarction: the controversy over prophylactic or selective use

In acute myocardial infarction, lidocaine is considered the drug of choice for the treatment of malignant ventricular arrhythmias. While initially a so-called "selective" treatment strategy prevailed, in which lidocaine was administered only after the onset of certain "warning arrhythmias," the prophylactic use of lidocaine in acute myocardial infarction has been gaining wider usage in intravenous and intramuscular application in recent years. Both therapeutic applications have been found to be problematic of late, which has led to increasingly restrictive use of lidocaine. While in selective treatment forms, the definition and prompt recognition of the so-called warning arrhythmias created especially acute problems, the prophylactic therapeutic use is problematic due to the occurrence of sometimes serious side effects, which is to be expected as the size of the collective being treated increases. Both treatment forms also appear limited by the narrow preventive efficacy of lidocaine against malignant ventricular arrhythmias, especially against ventricular fibrillation. The current therapeutic recommendation for lidocaine in acute myocardial infarction should be limited to patients presenting with very frequent and complex ventricular arrhythmias, especially when these are elicited by an R-on-T phenomenon. Side effects and other therapeutic problems encountered when the therapeutic modality is switched or adjusted can be greatly reduced by careful dosing and selection of the optimal combination substances.

[Transfemoral, transatrial double-balloon valvuloplasty of rheumatic mitral stenosis]

A percutaneous transfemoral, transatrial double-balloon valvuloplasty was performed on 21 patients (53 +/- 14 years) with rheumatic mitral stenosis. An open commissurotomy was performed in six patients, 20 +/- 9 years previously; in three patients an arterial embolism had occurred previously. Balloon valvuloplasty resulted in a reduction of the mean diastolic gradient from 16 +/- 7 to 8 +/- 3 mm Hg (p less than 0.001), and the mitral valve orifice area increased from 1.1 +/- 0.3 to 2.2 +/- 0.8 cm2 (p less than 0.001). Mitral insufficiency increased in three patients and was first observed after valvuloplasty in four patients. Complications were seen in three patients: a left ventricular perforation resulting in pericardial tamponade occurred in two patients, which required cardiothoracic intervention. In one patient a pulmonary embolism occurred five days after the invasive procedure. The study shows that percutaneous transfemoral balloon valvuloplasty can successfully be performed in patients with severe or even calcified mitral valve stenosis. The risk of severe complications is, however, not negligible.

ECG variants and cardiac arrhythmias in athletes: clinical relevance and prognostic importance

These findings permit the following conclusions on cardiac changes induced by high-performance sports and high levels of training. Sinus bradycardia and AV block can frequently be observed in athletes, but they do not require attention as long as they are asymptomatic or do not produce pauses exceeding 4 seconds. Persistent rather than transient second-degree AV block or Mobitz second- or third-degree AV block is an extremely unusual finding even in athletes and should be considered a sign of organic lesions until proved otherwise. Supraventricular and AV node ectopic beats are not more frequent in athletes than in the general population except for atrial fibrillation. WPW syndrome is of particular importance, since rapid conduction to the ventricle via the accessory AV pathway is possible, especially if there is a tendency toward atrial fibrillation. Likewise caution is required in athletes with hypertrophic cardiomyopathy. Here hemodynamic deterioration must be anticipated with the occurrence of supraventricular tachycardia. Simple ventricular arrhythmias occur among athletes with the same frequency as in the general population, but they usually disappear with exercise. The occurrence of complex ventricular forms of arrhythmia should always prompt cardiologic examination in search of underlying cardiac disease, particularly hypertrophic or dilated cardiomyopathy. The presence of ventricular arrhythmias without evidence of underlying heart disease does not indicate a special or increased risk of sudden cardiac death. A higher incidence of right and/or left ventricular hypertrophy, exercise-reversible ST elevation, and exercise-reversible changes in T waves (T negativity, sharp and/or excessive T waves) can be considered physiologic changes in the ECGs of athletes. These changes correlate closely with the type of sports activity and degree of training and are reversible when the activity is stopped. Horizontal ST segment depression are by contrast very rare in athletes and should always be clarified by cardiologic examination. Exercise-induced sudden cardiac death in athletes is unusual without preexisting heart disease. The cause of sudden cardiac death among athletes less than 40 years of age can be predominantely ascribed to congenital heart diseases (such as hypertrophic cardiomyopathy or coronary anomalies). In athletes more than 40 years of age and with increasing age, coronary heart disease is the most frequent autopsy finding. A corresponding risk stratification should take these partial dangers into account.

[How are tachycardic cardiac arrhythmias modified by therapy of congestive heart failure?]

Previous studies have demonstrated the high prevalence of frequent and complex ventricular arrhythmias in patients with severe congestive heart failure. It has been claimed that these arrhythmias are independent risk factors of prognosis. Moreover in severely depressed left ventricular function frequent and repetitive arrhythmias may deteriorate the hemodynamic situation. Recent clinical studies have drawn increasing attention to the possibility that the desired therapeutic effect of Class I antiarrhythmic agents may be complicated by their ability to aggravate the arrhythmia or to provoke new arrhythmias. These "proarrhythmical effects" were more frequent in patients with life-threatening arrhythmias and in those with severely depressed left ventricular function. Prevention trials with Class I antiarrhythmic agents have failed to show beneficial effects on the arrhythmia profile and on the prognosis of those patients. On the other hand, it is now well recognized that the incidence of cardiac death can be reduced by the use of ACE-inhibitors in this patient population. Accordingly, there is evidence of a reduced incidence of complex ventricular arrhythmias during treatment with these drugs in some of the patients with congestive heart failure. The influence of digitalis on the arrhythmia profile and the cardiac mortality in these patients is still a matter of debate. On the other hand, there is evidence that newer positive inotropic agents such as phosphodiesterase-inhibitors rather increase the number of arrhythmias and the prevalence of sudden cardiac death in this patient population.

[Predictive value of programmed electrostimulation in patients with spontaneous idiopathic ventricular tachycardia]

In contrast to patients with organic heart disease, there are only few data available on the incidence and type of inducible arrhythmias during programmed electrical stimulation (PES) in patients with spontaneous ventricular tachycardia (VT) but without evidence of underlying heart disease. Additionally, no consensus has been achieved in these patients on the most appropriate stimulation protocol required to reproduce the clinical arrhythmia. In a prospective study we analyzed in 40 patients without idiopathic VT, incidence and type of inducible VT, as well as the mode of initiation during a right ventricular PES protocol with 1-2 (part I) and three extrastimuli (part II). Twelve patients had spontaneous sustained monomorphic VT (group A), 28 patients were studied with spontaneous non-sustained VT (group B). During PES, a non-sustained polymorphic VT was induced in 3/12 patients (group A, 25%) and in 10/28 patients (group B, 36%); a non-sustained monomorphic VT was induced in 5/12 patients (group A, 41%) and in 4/28 patients (group B, 14%). In all 7/12 patients (59%) of group A with inducible sustained monomorphic VT, the arrhythmia was initiated with 1-2 extrastimuli. In group B, only 2/28 patients (7%) were induced to a sustained monomorphic VT. When the clinical arrhythmia was exercise-related, 5/6 patients (83%) in group A and 7/13 patients (54%) in group B were induced to a VT, while 2/6 patients (33%) in group A and 1/13 (8%) patients in group B were induced to a sustained monomorphic VT. Isoprenaline was not effective to increase the incidence of sustained monomorphic VT.(ABSTRACT TRUNCATED AT 250 WORDS)

An epidemiological study assessing the relative importance of airborne and direct contact transmission of microorganisms in a medical intensive care unit

A prospective epidemiological survey was carried out over a period of seven weeks in a medical intensive care unit. Bacteria from patients, staff and air were monitored and the transmission of isolated microorganisms was followed. Handwashing samples revealed pathogenic bacteria in 30.8% of physicians (average number of colony forming units: 71,300 per hand) and 16.6% of nurses (39,800 cfu per hand). Air cultures yielded pathogens in 15% of sampling periods and nine of 53 patients were found to be colonized with Gram-negative bacteria, Staphylococcus aureus or Candida spp. The spectrum of bacteria recovered from patients and air was generally different, whereas strains recovered from patients and their attendants' hands were indistinguishable on multiple occasions. The results of this study confirm that direct contact is the principal pathway of microbial transmission, whereas little evidence for a significant role of airborne transmission is shown. The call for more extensive air-filtering and ventilation systems in medical intensive care units is not supported by the results shown in this communication.

Vasodilatory action of endogenous atrial natriuretic factor in a rat model of chronic heart failure as determined by monoclonal ANF antibody

Elucidation of the role of (elevated) endogenous atrial natriuretic factor (ANF) in chronic heart failure has been hampered by a lack of specific inhibitors. We used a newly developed monoclonal antibody that has been shown to specifically block both exogenously and endogenously released ANF in vivo. For assessment of the vasodilatory action of ANF in chronic heart failure, either this antibody against ANF or ascites (control serum) was injected in rats with myocardial infarction and failure and in sham animals. Ascites did not alter central hemodynamics in either the sham or infarcted group. Antibody significantly increased right atrial pressure, left ventricular end-diastolic pressure, and systemic vascular resistance (SVR) in the infarction group but did not affect these variables in the sham group. Because renal blood flow, as measured by radioactive microspheres, decreased significantly in all four groups, probably due to nonspecific renal vasoconstrictor effects of the ascites, a separate group of infarcted animals was treated with purified ANF antibody (devoid of nonspecific effects) or mouse IgG as a control injection. In these animals, right atrial pressure increased from 1.1 +/- 0.7 to 2.6 +/- 0.7 mm Hg (p less than 0.001). Although SVR, renal blood flow velocity (measured by Doppler probe), and renal vascular resistance did not change in the infarcted animals after administration of purified ANF antibody, a significant correlation was found between baseline plasma ANF values and the change in SVR exerted by purified ANF antibody (r = 0.758, p less than 0.02, n = 9); that is, SVR increased in rats with high baseline plasma ANF (greater than 350 pg/ml), but decreased in animals with plasma ANF less than 200 pg/ml. These results suggest that moderately elevated endogenous plasma ANF levels in chronic heart failure do affect central hemodynamics, primarily by reducing venous pressure (e.g., by decreasing intravascular volume or by venous dilation). Arterial vasodilation, however, appears to emerge when plasma ANF is greatly increased.

Reocclusion prophylaxis with dipyridamole combined with acetylsalicylic acid following PTA

After primary successful PTA, 199 patients were randomized into one of three treatment groups, namely, placebo or a combination of 75 mg dipyridamole with either 330 mg (high dose) or 100 mg (low dose) acetylsalicylic acid (ASA) tid. The duration of treatment was six months. Of the 199 patients admitted to the study, 156 completed the six-month trial period. Not all patients had a second angiogram, and in these cases clinical findings were used in the evaluation. Evaluation of the combined angiographic and clinical results showed improvement or no deterioration in 37% of patients in the placebo group compared with 49% in the low-dose and 61% in the high-dose ASA groups respectively. The only statistically significant difference observed was between the placebo group and the group treated with dipyridamole and high-dose ASA (p = 0.01). This difference remained statistically significant at p = 0.039 if only the angiographic findings were considered for group comparison. It cannot, however, be concluded from this study that 75 mg dipyridamole in combination with 100 mg ASA tid is more effective in preventing reocclusion after PTA than in combination with 330 mg ASA tid.

Repeat determination of left ventricular wall thickness from mass and volume during one cardiac cycle for the calculation of left ventricular wall stress parameters

Left ventricular end-diastolic wall stress, end-systolic wall stress, and systolic stress-time integral are important parameters to characterize left ventricular load and function. To obtain these parameters, left ventricular pressure, volume, and wall thickness data must be determined at short time intervals throughout one cardiac cycle. However, the measurement of wall thickness at short intervals (i.e., 20 ms) throughout a cardiac cycle is tedious. Furthermore, measurements of wall thickness are less accurate at end-systole compared with end-diastole. For these reasons we developed a computer program for calculating wall thickness at short intervals (20 ms) throughout the cardiac cycle from one single determination of left ventricular wall mass and repetitive measurements of left ventricular (LV) volume.

[Transesophageal and Doppler ultrasound studies before and following percutaneous balloon valvuloplasty of the aortic valve]

Transesophageal and Doppler-echocardiography were performed in 25 patients with severe valvular aortic stenosis before and after percutaneous balloon valvuloplasty. The maximal systolic gradient over the aortic valve determined during invasive measurements before and after valvuloplasty decreased from 71 +/- 24 mm Hg to 36 +/- 14 mm Hg; the mean systolic gradient decreased from 53 +/- 18 mm Hg to 28 +/- 10 mm Hg. The aortic orifice area increased from 0.67 +/- 0.2 to 0.94 +/- 0.2 cm2. During transesophageal echocardiography the aortic orifice area was calculated by direct planimetry. The aortic valve area increased from 0.52 +/- 0.21 cm2 before the valvuloplasty to 0.72 +/- 0.17 cm2 after intervention. After valvuloplasty small thrombotic vegetations were observed in four patients and valvular lesions in two patients. Using Doppler-echocardiographic measurements to quantify the aortic valve stenosis the maximal instantaneous gradient decreased from 94 +/- 30 before valvuloplasty to 66 +/- 25 mm Hg after valvuloplasty; the mean instantaneous gradient changed from 52 +/- 17 to 37 +/- 14 mm Hg. The aortic orifice area increased from 0.5 +/- 016 to 0.76 +/- 0.21 cm2. These results confirm that transesophageal and Doppler-echocardiography are appropriate to control the success of percutaneous balloon valvuloplasty.

Modulation of myothermal economy of isometric force generation by positive inotropic interventions in the guinea pig myocardium

Isometric force development has been measured simultaneously with liberated heat in papillary muscles from the right ventricle of the guinea pig, using rapid antimony-bismuth thermopiles. The following components of the contractile cycle and their relation to energy consumption were evaluated: (1) basal metabolism; (2) crossbridge cycling; (3) calcium cycling; and (4) recovery processes. The influences of isoproterenol, high calcium and UDCG-115, a calcium-sensitizing substance, on these four energy compartments of the muscle were studied relative to their positive inotropic effects. Isoproterenol increased initial heat per peak developed tension or per tension-time integral from 7.4 +/- 1.55 to 11.65 +/- 1.15 mucal/g cm (p less than 0.02) or from 4.52 +/- 0.79 to 8.14 +/- 0.77 mucal/g cm sec (p less than 0.01), respectively. In contrast, these ratios were unchanged from control values by positive inotropic interventions with 11 mM calcium or UDCG-115. The increase of initial heat for a unit of mechanical activity due to isoproterenol is attributable to activation and contractile protein processes, i.e. the activation heat increased from 0.24 +/- 0.05 to 0.68 +/- 0.13 mcal/g (p less than 0.01) and tension-dependent heat per tension-time integral increased from 2.24 +/- 0.60 to 5.18 +/- 0.89 mucal/g cm sec (p less than 0.01). We conclude that isoproterenol increases the number of calcium ions released into the sarcoplasm during each activation cycle. It also alters the rate of crossbridge cycling associated with a decreased economy of force generation.(ABSTRACT TRUNCATED AT 250 WORDS)