Cardiac remodelling: concentric versus eccentric hypertrophy in strength and endurance athletes.

Cardiac remodelling is commonly defined as a physiological or pathological state that may occur after conditions such as myocardial infarction, pressure overload, idiopathic dilated cardiomyopathy or volume overload. When training excessively, the heart develops several myocardial adaptations causing a physiological state of cardiac remodelling. These morphological changes depend on the kind of training and are clinically characterised by modifications in cardiac size and shape due to increased load. Several studies have investigated morphological differences in the athlete's heart between athletes performing strength training and athletes performing endurance training. Endurance training is associated with an increased cardiac output and volume load on the left and right ventricles, causing the endurance-trained heart to generate a mild to moderate dilatation of the left ventricle combined with a mild to moderate increase in left ventricular wall thickness. Strength training is characterised by an elevation of both systolic and diastolic blood pressure. This pressure overload causes an increase in left ventricular wall thickness. This may or may not be accompanied by a slight raise in the left ventricular volume. However, the development of an endurancetrained heart and a strength-trained heart should not be considered an absolute concept. Both forms of training cause specific morphological changes in the heart, dependent on the type of sport. (Neth Heart J 2008;16:129-33.).

Prognostic value of Q waves, R/S ratio, loss of R wave voltage, ST-T segment abnormalities, electrical axis, low voltage and notching: correlation of electrocardiogram and left ventriculogram.

Data on the correlation of left ventricular segmental wall motion and electrocardiographic findings are, except for Q waves and ST segment elevation, still controversial. Therefore, in addition to Q waves and ST segment elevation, eight features of the electrocardiogram were studied in 265 patients, 61 with normal coronary arteries and 204 with coronary artery disease. Patients with a QRS duration of 0.12 second or greater were excluded. Left ventricular wall motion was assessed in the 30 degrees right anterior oblique and the 60 degrees left anterior oblique projections and analyzed by the Stanford method and a modification of that method, respectively. Asynergy of a particular segment correlated well with the presence of Q waves in the corresponding electrocardiographic lead or leads, but was also found in other segments. There was a significant (p less than 0.001) correlation between the number of leads with Q waves and the degree of extension of asynergy. The R/S ratio in lead V1 and Q waves in lead V6 appeared to be the most informative about the posterior wall. Loss of R wave voltage had a lower predictive value for segmental asynergy than did Q waves in the same lead. Among patients with electrocardiographic findings of an infarct, asynergy was found in 83 to 94%. Patients having Q waves in combination with ST segment elevation manifested more severe asynergy than did patients whose Q waves were not associated with ST elevation. New data are presented for lateral and posterior infarction. Patients having left-axis deviation, low voltage and QRS notching had severe asynergy.(ABSTRACT TRUNCATED AT 250 WORDS)

Extrastimulus-related shortening of the first postpacing interval in digitalis-induced ventricular tachycardia: observations during programmed electrical stimulation in the conscious dog.

The effect of different modes of pacing on interval and configuration of the first postpacing QRS complex was studied during digitalis-induced ventricular tachycardia in the conscious dog. The effect of overdrive pacing was related to pacing rate; the longest pacing intervals resulted in prolongation of the first postpacing interval, while increasing the rate of overdrive pacing led to a progressive shortening of the first postpacing interval. When extrastimuli were introduced during fixed rate pacing, the duration of the first postpacing interval was found to be predominantly effected by the extrastimulus coupling interval. The importance of the last paced interval to the duration of the first postpacing cycle length was also observed when only a single or two extrastimuli were given. The duration of the first postpacing interval was found to be independent of the site site of stimulation. In contrast, the configuration of the first postpacing QRS complex was found to be related to the site of pacing; the first postpacing QRS complex originated close to the site of stimulation independent of the configuration of the tachycardia. In conclusion, it was found that during digitalis-induced ventricular tachycardia 1) the first postpacing interval is mainly, dependent on the interval of the last paced beat, 2) the length of the first postpacing interval is independent of the site of stimulation, but 3) the configuration of the first postpacing QRS complex is related to the site of stimulation. These findings may facilitate the understanding of complex ventricular arrhythmias observed during severe digitalis intoxication in human beings.

Did prognosis after acute myocardial infarction change during the past 30 years? A meta-analysis.

Much effort has been spent to improve survival after acute myocardial infarction. To investigate how effective this effort has been, a meta-analysis was performed of studies published between 1960 and 1987 concerning mortality after acute myocardial infarction. Thirty-six studies were analyzed. They were classified with respect to deaths in the hospital and at 1 month and the 5-year mortality rate starting at hospital discharge. Mortality was assessed from all studies by comparing studies from different institutions with use of identical inclusion criteria (externally controlled studies) and by analyzing studies reporting on changes in mortality in two or more comparable patient cohorts admitted to the same institution at different time periods (internally controlled studies). Reports on clinical trials (for example, thrombolytic therapy, beta-adrenergic blockade) in acute myocardial infarction were excluded. Average overall in-hospital mortality decreased from 29% during the 1960s to 21% during the 1970s and to 16% during the 1980s. The externally controlled studies also showed a declining trend: from 1960 to 1969, 32%, from 1970 to 1979, 19% and from 1980 to 1987, 15%. The 1-month overall mortality rate decreased from 31% during the 1960s to 25% during the 1970s and 18% during the 1980s externally controlled studies. Most internally controlled studies also showed significant improvement in in-hospital and 1-month survival. In contrast, 5-year mortality after hospital discharge did not significantly decrease (33% from 1960 to 1969 and 33% from 1970 to 1979). It is concluded that in the prethrombolytic era, short-term prognosis after acute myocardial infarction has improved since 1960.(ABSTRACT TRUNCATED AT 250 WORDS)

Value of the electrocardiogram in localizing the occlusion site in the left anterior descending coronary artery in acute anterior myocardial infarction.

OBJECTIVES: The study assessed the value of the electrocardiogram (ECG) as predictor of the left anterior descending coronary artery (LAD) occlusion site in relation to the first septal perforator (S1) and/or the first diagonal branch (D1) in patients with acute anterior myocardial infarction (AMI). BACKGROUND: In anterior AMI, determination of the exact site of LAD occlusion is important because the more proximal the occlusion the less favorable the prognosis. METHODS: One hundred patients with a first anterior AMI were included. The ECG showing the most pronounced ST-segment deviation before initiation of reperfusion therapy was evaluated and correlated with the exact LAD occlusion site as determined by coronary angiography. RESULTS: ST-elevation in lead aVR (ST elevation(aVR)), complete right bundle branch block, ST-depression in lead V5 (ST depression(V5)) and ST elevation(V1) > 2.5 mm strongly predicted LAD occlusion proximal to S1, whereas abnormal Q-waves in V4-6 were associated with occlusion distal to S1 (p = 0.000, p = 0.004, p = 0.009, p = 0.011 and p = 0.031 to 0.005, respectively). Abnormal Q-wave in lead aVL was associated with occlusion proximal to D1, whereas ST depression(aVL) was suggestive of occlusion distal to D1 (p = 0.002 and p = 0.022, respectively). For both the S1 and D1, inferior ST depression > or = 1.0 mm strongly predicted proximal LAD occlusion, whereas absence of inferior ST depression predicted distal occlusion (p < or = 0.002 and p < or = 0.020, respectively). CONCLUSIONS: In anterior AMI, the ECG is useful to predict the LAD occlusion site in relation to its major side branches.

Cardiac remodeling after myocardial infarction is impaired in IGF-1 deficient mice.

OBJECTIVE: To obtain more insight in the role of IGF-1 in cardiac remodeling and function after experimental myocardial infarction. We hypothesized that cardiac remodeling is altered in IGF-1 deficient mice, which may affect cardiac function. METHODS: A myocardial infarction was induced by surgical coronary artery ligation in heterozygous IGF-1 deficient mice. One week after surgery, left ventricular function was analyzed, and parameters of cardiac remodeling were measured. RESULTS: No significant difference in cardiac function was found between infarcted wildtype and knock-out animals, despite a marked reduction in capillarization and blunting of the hypertrophic response of the interventricular septum in the IGF-1 deficient group. Furthermore, decreased DNA synthesis and increased apoptosis rates were observed in the IGF-1 knock-out mice. CONCLUSION: IGF-1 deficient mice show preservation of cardiac function 1 week after MI, despite an altered cardiac remodeling process.

Differential diagnosis of tachycardia with narrow QRS complex (shorter than 0.12 second).

One hundred eighty-seven patients with clinically documented supraventricular tachycardia with a narrow QRS complex were admitted for electrophysiologic study. The diagnoses after this study were circus movement tachycardia using an accessory pathway in 50 patients, atrioventricular nodal tachycardia in 50 patients, atrial flutter in 50 patients, atrial tachycardia in 27 patients and an incessant tachycardia retrogradely using a slowly conducting accessory pathway in 10 patients. On retrospective analysis, 5 criteria on the 12-lead electrocardiogram during tachycardia were analyzed for their value in making the diagnosis of site of origin. These criteria were P-wave location, axis of the P wave, atrial rate, alternation of the QRS complex and atrioventricular relation. Fifty-seven patients with a narrow QRS tachycardia were prospectively studied using the 5 criteria. A correct diagnosis was made in 48 of the 57 patients (84%). Thus, in most patients with a narrow QRS tachycardia, information from the 12-lead electrocardiogram is adequate for diagnosis.

Value of the ajmaline-procainamide test to predict the effect of long-term oral amiodarone on the anterograde effective refractory period of the accessory pathway in the Wolff-Parkinson-White syndrome.

In patients with the Wolff-Parkinson-White syndrome, intravenous ajmaline (50 mg administered over 3 minutes) or procainamide (10 mg/kg body weight administered over 10 minutes) is helpful in defining the duration of the anterograde effective refractory period of the accessory pathway. In this study the value of the ajmaline-procainamide test to predict the effects on the anterograde effective refractory period of the accessory pathway of long-term oral amiodarone were assessed. Thirty-six patients with the Wolff-Parkinson-White syndrome were studied. Twenty-four (Group A) had a negative result of the ajmaline-procainamide test and a mean duration of the anterograde effective refractory period of the accessory pathway of 237 +/- 24 ms. Twelve (Group B) had a positive result in the ajmaline-procainamide test (disappearance of preexcitation during sinus rhythm after administration of ajmaline and procainamide) and a duration of the anterograde effective refractory period of the accessory pathway of 284 +/- 25 ms (p less than 0.05 versus values in Group A). Amiodarone prolonged the anterograde effective refractory period of the accessory pathway by 53 +/- 35 ms in patients in Group A to 290 +/- 37 ms (p less than 0.001) and by 100 +/- 85 ms in patients in Group B to 384 +/- 94 ms (p less than 0.001). The difference in mean increase between both groups was not significant. In most patients (83%) in Group A amiodarone prolonged the anterograde effective refractory period of the accessory pathway to 260 to 330 ms. However, in most patients (83%) in Group B, amiodarone prolonged the anterograde effective refractory period of the accessory pathway to greater than or equal to 330 ms (p less than 0.01). Thus, an ajmaline-procainamide test is of value in predicting the results of oral amiodarone on the anterograde effective refractory period of the accessory pathway.

Observations on spontaneous termination of atrioventricular nodal reentrant tachycardia.

Unusual mechanisms of spontaneous termination of atrioventricular (A-V) nodal reentrant tachycardia were observed in two patients during programmed electrical stimulation of the heart. In both patients the mechanism of termination was based on the use of another reentrant pathway than the use used during tachycardia. This pathway was located extranodally in one patient and intranodally in the other. The observations illustrate some of the complexities of reentry in the human heart and how they can play a role in spontaneous termination of A-V nodal tachycardia.

Effect of drugs in the Wolff-Parkinson-White syndrome. Importance of initial length of effective refractory period of the accessory pathway.

The effect of procainamide, quinidine, ajmaline and amiodarone on the effective refractory period of the accessory pathway in the (A-V) anterograde and retrograde directions was studied in relation to the length of this period before drug administration. All patients had the Wolff-Parkinson-White syndrome and were studied with intracavitary recordings and programmed electrical stimulation of the heart using identical basic cycle lengths and test stimulus intervals before and after drug administration. The patients were separated into two groups, those in whom the effective refractory period of the accessory pathway was 270 ms or greater (Group 1) and those in whom it was less than 270 (Group 2). In the anterograde direction the magnitude of increase in the length of the effective refractory period of the accessory pathway after drug administration was related to its initial length. Only modest lengthening of this period could be accomplished in patients with an initially short period. In evaluating the effect of drugs in patients with the Wolff-Parkinson-White syndrome, the role of the initial length of the effective refractory period of the accessory pathway should be considered.

Changes in wall motion in patients treated for unstable angina. A suggestion of the stunned and hibernating myocardium in humans. UNASEM Collaborative Study Group. Unstable Angina Study Using Eminase.

BACKGROUND: A double-blind, placebo-controlled study using anistreplase was performed in 159 patients with unstable angina. All patients had a history of unstable angina combined with typical ECG changes and without evidence of a previous, recent, or ongoing myocardial infarction. The purpose of the present study was to analyze the relationship between the patency of the culprit artery and the behavior of the ischemia-related regional left ventricular (LV) wall motion. METHODS AND RESULTS: On entry to the study, all patients received conventional drug therapy: i.v. nitroglycerin therapy, an oral beta-blocking agent, and a calcium antagonist. Baseline angiography was carried out within 3 h after randomization, a mean of 4.2 +/- 3.0 h (range, 1 to 17 h) after the last attack of chest pain. Treatment with trial medication was withheld in 33 cases. Sixty-five patients with coronary artery disease received anistreplase (30 U/5 min)/heparin and 61 patients heparin-only therapy. Angiography was repeated 20.6 +/- 4.6 h (mean +/- SD; range, 12 to 39 h) after the baseline angiographic study. To assess changes in regional myocardial wall motion, the LV wall was divided into seven segments. The ischemia-related coronary artery stenosis was calculated quantitatively and related to the quantitatively assessed mean regional left ventricular ejection fraction (RLVEF) of the ischemia-related segments. In 118 of 126 patients who received trial medication, we found that anistreplase/heparin therapy leads to a significantly (p < 0.01) greater reduction in coronary artery diameter stenosis than heparin-only therapy (n = 63, mean +/- SD, 11 +/- 22, vs n = 55, mean +/- SD, 3 +/- 11%). Anistreplase/heparin therapy was related to a larger significant improvement of the ischemia-related RLVEF than heparin-only therapy, although the latter association was not statistically significant (n = 63, mean +/- SD, 7 +/- 15, vs n = 55, mean +/- SD, 5 +/- 14%). The effects of change of coronary artery stenosis on regional LV wall motion were also determined. A paradoxical finding was that a persistently occluded vessel or a vessel showing an increase in coronary artery stenosis was associated with a greater improvement of the ischemia-related RLVEF than a reopened vessel or a vessel with a reduction in coronary artery stenosis (n = 15, mean +/- SD, 7 +/- 11, vs n = 41, mean +/- SD, 8 +/- 13, vs n = 15, mean +/- SD, 1 +/- 12, vs n = 47, mean +/- SD, 5 +/- 16%, NS). One day after the last attack of chest pain, the regional LV wall motion was still abnormal in about 20% of patients. CONCLUSION: In these patients with unstable angina, the LV wall motion improved both in the treated and the control group at follow-up angiography 1 day later. Improved coronary arterial anatomy was associated with a lesser improvement of the LV contractile function than when worsening of the coronary angiographic appearance occurred. There is no rational explanation of these results. This is a beginning of an effort to elucidate the clinical significance of the stunned and hibernating myocardium in humans.

Right ventricular support for off-pump coronary artery bypass grafting studied with bi-ventricular pressure--volume loops in sheep.

OBJECTIVES: Tilting the heart during off-pump coronary artery bypass grafting (OPCABG) causes a strong decrease in cardiac output. It is hypothesized that this decrease is caused by reduced right ventricular filling and that right ventricular support is thus the best way to restore cardiac output. Simultaneous left and right ventricular pressure-volume loops were used to test this hypothesis. METHODS: In seven sheep, the heart was tilted with the use of an Octopus device. After unsupported tilting, a novel right ventricular support, the Enabler, was activated at a pulsatile flow of 1.6 l/min. Pressure-volume loops of both ventricles were obtained using conductance catheters, and cardiac output was monitored with an aortic flow probe. RESULTS: Tilting reduced cardiac output by 31% (4.4--3.1 l/min, P=0.001) and right ventricular end-diastolic volume by 44% (86--51 ml, P=0.005), while right ventricular end-diastolic pressure did not decrease. Left ventricular systolic pressure was not significantly reduced upon tilting and even increased in two animals. During Enabler right ventricular support, the cardiac output remained 23% lower than pre-tilting values (3.4 vs. 4.4 l/min, P=0.001). CONCLUSIONS: Restricted right ventricular filling is the primary cause of the strong decrease in cardiac output during tilting. The Enabler right ventricular support can currently not restore cardiac output to pre-tilting values, mainly caused by its limited output and a decrease in right ventricular output upon Enabler activation. Constant monitoring of cardiac output is crucial during (unsupported or supported) tilting as blood pressure alone may not reflect the extent of the reduction in cardiac function.

Evaluation of new self-learning techniques for the generation of criteria for differentiation of wide-QRS tachycardia in supraventricular tachycardia and ventricular tachycardia.

This study presents a comparison of three different methods for differentiating between supraventricular and ventricular tachycardias with wide-QRS complex. One set of criteria, derived using classical statistical techniques, was compared with two new self-learning computer techniques: the artificial neural networks and the induction algorithm approach. By analyzing the results obtained in an independent test set, using these new techniques, the criteria defined by the classical method could be improved.

The value of an expert system in performing clinical drug trials.

An expert system has been designed to assist the cardiologist in determining whether patients can be included in clinical trials. This system contains knowledge on inclusion and exclusion criteria for six drug trials, and has been validated in 100 randomly selected patients. In 97 cases, the expert system and the cardiologist made an identical classification; in the remaining three cases, the patient was incorrectly classified by the physician. The system will also optimize the order in which questions are asked in order to minimize the time required to decide on inclusion or exclusion.

The future of cardiovascular imaging and non-invasive diagnosis: a joint statement from the European Association of Echocardiography, the Working Groups on Cardiovascular Magnetic Resonance, Computers in Cardiology, and Nuclear Cardiology, of the European Society of Cardiology, the European Association of Nuclear Medicine, and the Association for European Paediatric Cardiology.

Advances in medical imaging now make it possible to investigate any patient with cardiovascular disease using multiple methods which vary widely in their technical requirements, benefits, limitations, and costs. The appropriate use of alternative tests requires their integration into joint clinical diagnostic services where experts in all methods collaborate. This statement summarises the principles that should guide developments in cardiovascular diagnostic services.

Modern pacemakers: implantable artificial intelligence?

For over twenty years computer programs have been written for applications in cardiology. Approximately one decade ago the first Expert Systems using knowledge on cardiology were built. The use of Expert System shells enabled a breakthrough. Many systems were developed, each covering a small part of cardiology. In the pacing environment Expert Systems can be used to select the optimal pacemaker therapy or to analyze complex pacemaker electrocardiograms. With the help of these artificial intelligence techniques pacemakers can be designed, that behave in an intelligent way. Finally this knowledge representation enables the reproducible simulation of the heart-pacemaker interaction.

Artificial neural networks and ECG interpretation. Use and abuse.

The computerized interpretation of the resting electrocardiogram has reached a steady-state phase: an equilibrium between sensitivity and specificity has been reached. New computer techniques, such as expert systems and artificial neural network technology, have been proposed or are currently under evaluation. Although neural network techniques are based on complex mathematical theories and their application is full of pitfalls, progress has been made in a number of subdomains, like signal filtering, electrocardiographic classification, and compression of stress electrocardiograms. Presently, the hesitating acceptance by the human user forms one of the obstacles that needs to be overcome by convincing, well-performed studies.

The impact of the millennium problem on implantable pacemakers and defibrillators.

The unpredictable behavior of computer systems on January 1, 2000, known as the millennium problem or millennium 'bug,' also affects medical establishments and, due to the large use of computers in all kind of applications, cardiological clinics in particular. This review discusses the effect of the millennium computer problem on the implantation procedures and follow-up registries of implantable pacemakers and defibrillators. The review concludes that the transition in the next millennium will not influence the proper functioning of implanted pacemakers and defibrillators. The function of pacemaker/defibrillator programmers seems to be safe and no major difficulties are anticipated. Pacemaker databases and the logistics linked to the implantation and follow-up of patients and their pacemaker may and probably will be affected by the millennium transition. Using the FDA database on biomedical equipment, the actual status of all biomedical devices can be assessed.