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PubMed1980

Detection, significance and management of VPBs in ambulatory patients.

The detection, clinical significance, and management strategies of VPBs in ambulatory patients have been presented. VPBs can be easily detected by a variety of recording techniques, and the major risk posed by VPBs occurs predominantly in patients with complex VPB patterns and concomitant organic heart disease. Available antiarrhythmic therapy is quite limited, and efficacy, convenience, and tolerance considerations dictate a conservative approach to initiating therapy. Risk-benefit considerations must be reasoned through in each patient. Presently, drug risks closely approximate those of the underlying cardiac condition, and the benefits from antiarrhythmic drug therapy are marginal at the very best. However, antiarrhythmic therapy has special relevance for the high risk cardiac patient. A Yiddish proverb states, "Ever since dying came into fashion, life hasn't been safe." Hopefully, antiarrhythmic therapy is making life safer for the high risk ambulatory patient.

Ambulatory Care↗
PubMed2003

Age and racial/ethnic differences in maternal, fetal, and placental conditions in laboring patients.

OBJECTIVE: Most health indicators exhibit evidence of ethnic disparity. This study describes the prevalence of clinical conditions that are associated with pregnancy, stratified at age 35 years, and by ethnicity (black, white, Hispanic, other). STUDY DESIGN: This was a retrospective, cross-sectional cohort study. We used International Classification of Diseases discharge diagnostic codes from California discharge data to identify 31 maternal, fetal, and placental conditions. RESULTS: At least one condition was present for 26.1% of the 443,532 eligible women. There was variation in risk by age and race/ethnicity and differences by age within ethnic groups. Black women were more at risk; there are 12 conditions for older women, and there are 16 conditions for younger women. Hispanic women showed a higher risk for diabetes mellitus, macrosomia, and severe hypertension. All white women showed a higher risk for cardiac conditions and isoimmunization, whereas older white women also demonstrated an increased risk for herpes infection and multiple gestation. CONCLUSION: Older women and black women have more morbidity. The degree to which these clinical conditions affect labor management and obstetric outcomes needs further evaluation.

Adult↗
PubMed2002

A need for an individualized approach to end-stage renal disease patients.

Evidence suggests that an individualized and flexible approach may be beneficial to end-stage renal disease (ESRD) patients. This article discusses this approach in relation to three issues: target haemoglobin (Hb) level, epoetin dosing frequency/administration and patient management/education programmes. Trial data indicate that each patient's condition should be taken into account when assigning target Hb values. Normalization of Hb is unlikely to be protective in patients with well-established cardiac disease. However, in patients without severe cardiac conditions, normalization is associated with benefits, such as reduction of cardiovascular risk factors and improved quality of life. Data are awaited from trials examining the impact of anaemia correction in patients not yet on renal replacement therapy (RRT). Two large, randomized controlled trials of haemodialysis patients have demonstrated that once-weekly epoetin beta is as effective and as well tolerated as administration two or three times weekly. Additionally, one of these trials showed that once-weekly and three times weekly administrations were equivalent therapeutically in terms of maintaining both stable haematocrit levels and epoetin beta dose requirements. These results suggest that the epoetin beta route and frequency of administration can be individualized according to patient/physician preference. Renal management programmes, which incorporate a multidisciplinary team approach, strategies for early referral of patients and patient education, have an impact on patient outcomes and on RRT modality choice. An individualized programme will help to optimize the use of treatments aimed at delaying the progression of renal failure and its co-morbidities. In conclusion, evidence suggests that an individualized and flexible approach to target Hb values, epoetin beta route and frequency of administration, and patient education/management programmes may be beneficial to patients with ESRD. As early intervention has an impact on patient outcome and the progression of risk factors, this approach may also be appropriate for patients who are not yet receiving RRT.

Anemia↗
PubMed1995

Embolic stroke following thrombolytic therapy for myocardial infarction in a patient with preexisting ventricular thrombi.

BACKGROUND: Dislodging of preexisting cardiac thrombi has been a reported but unconfirmed cause of embolic strokes after thrombolytic therapy for myocardial infarction. CASE DESCRIPTION: An 82-year-old woman was admitted with congestive heart failure. Initial echocardiogram demonstrated ventricular thrombi. Three days later she experienced an inferior wall myocardial infarction, and intravenous streptokinase was administered. Six hours later she abruptly developed a global aphasia with a dense right hemiparesis. Repeat echocardiogram did not show any thrombus. CONCLUSIONS: Thrombolytic therapy may have caused embolization of ventricular thrombi. Cardiac conditions that predispose to embolic strokes are not established contraindications to thrombolytic therapy. The potential for thrombolytic therapy to produce embolization in patients with preexisting cardiac mural thrombi should be evaluated.

Aged↗
PubMedDate not supplied

Survivors of sudden cardiac death: a rational approach to evaluation and therapy of patients surviving ventricular fibrillation.

Survivors of out-of-hospital cardiac arrest that is not associated with acute myocardial infarction are at high risk for subsequent life-threatening ventricular tachyarrhythmias. A rational approach to evaluating the underlying disease processes and to formulating a specific treatment plan for these patients is presented. A protocol is suggested whereby existing cardiac conditions are appropriately treated and hemodynamic parameters are optimized. Myocardial ischemia is minimized with drugs or revascularization; this may suffice to prevent recurrence of sudden cardiac death in a small group of patients. For remaining patients at high risk of recurrence, the implantable cardioverter-defibrillator is the therapy associated with the lowest rate of mortality.

Death, Sudden, Cardiac↗
PubMed2006

C2C12 skeletal muscle cells adopt cardiac-like sodium current properties in a cardiac cell environment.

Intracardiac transplantation of undifferentiated skeletal muscle cells (myoblasts) has emerged as a promising therapy for myocardial infarct repair and is already undergoing clinical trials. The fact that cells originating from skeletal muscle have different electrophysiological properties than cardiomyocytes, however, may considerably limit the success of this therapy and, in addition, cause side effects. Indeed, a major problem observed after myoblast transplantation is the occurrence of ventricular arrhythmias. The most often transient nature of these arrhythmias may suggest that, once transplanted into cardiac tissue, skeletal muscle cells adopt more cardiac-like electrophysiological properties. To test whether a cardiac cell environment can indeed modify electrophysiological parameters of skeletal muscle cells, we treated mouse C(2)C(12) myocytes with medium preconditioned by primary cardiocytes and compared their functional sodium current properties with those of control cells. We found this treatment to significantly alter the activation and inactivation properties of sodium currents from "skeletal muscle" to more "cardiac"-like ones. Sodium currents of cardiac-conditioned cells showed a reduced sensitivity to block by tetrodotoxin. These findings and reverse transcription PCR experiments suggest that an upregulation of the expression of the cardiac sodium channel isoform Na(v)1.5 versus the skeletal muscle isoform Na(v)1.4 is responsible for the observed changes in sodium current function. We conclude that cardiomyocytes alter sodium channel isoform expression of skeletal muscle cells via a paracrine mechanism. Thereby, skeletal muscle cells with more cardiac-like sodium current properties are generated.

Animals↗
PubMed1985

Dissociation of autonomic and behavioral components of conditioned fear during development in the rat.

Classical conditioning of heart rate (HR) was examined in unrestrained preweanling and weanling (16-, 19-, 21-, 25-, and 28-day-old) rats, with tone and light as the conditioned stimuli (CS) and electric shock as the unconditioned stimulus. The conditioned cardiac response was a sustained deceleration in HR which did not emerge until Day 21 for the tone CS and until Day 28 for the light CS. In contrast, when suppression of a behavioral response (running in a straight alley for dry suckling as reward) was used as the index of conditioning, the suppressive effects of the CS were evident around Day 16 for the tone and around Day 19 for the light. These findings indicate that during ontogenesis (a) the behavioral and autonomic responses to the same conditioned stimulus do not develop at the same pace, (b) the emergence of conditioned responses to tone and light stimuli parallel the sequential order in which the relevant sensory modalities achieve maturity (first audition, next vision), and (c) there is no clear-cut interdependence between development of the HR orienting response and conditionability of HR because unconditioned cardiac deceleration to both auditory and visual stimuli first appears about Day 16 in the developing rat, well before conditioned HR responses can be established to either stimulus.

Aging↗
PubMed2005

Differentiation between protective reflexes: cardiac defense and startle.

Rise time and duration are two parametric characteristics of the eliciting stimulus frequently used to differentiate among psychophysiological reflexes. The present research varied the duration (study 1) and rise time (study 2) of an intense acoustic stimulus to dissociate cardiac defense and cardiac startle using the eyeblink response as the external criterion of startle. In each study, 100 participants were presented with five white noise stimuli of 105 dB under one of five duration (50, 100, 250, 500, and 1000 ms) or rise time (0, 24, 48, 96, and 240 ms) conditions. Cardiac defense was affected by stimulus duration, present only in the 500- and 1000-ms conditions, but not by stimulus rise time, present in all rise time conditions. Rise time affected blink startle, but did not selectively alter the short latency accelerative component of the heart rate response, thus questioning whether it reflects startle.

Adolescent↗
PubMed1995

The discrepancy between echocardiography, cineventriculography and thermodilution. Evaluation of left ventricular volume and ejection fraction.

We have often experienced disagreement in left ventricular end-diastolic volume (EDV), end-systolic volume (ESV) and ejection fraction (EF) between cineventriculography and echocardiography not performed simultaneously, and unnaturally hyperdynamic left ventricular wall motion. We determined EDV, ESV, stroke volume, and EF (with modified Simpson's rule) in 65 consecutive patients using 2-dimensional echocardiography with a 2.5 MHz, 128-element phased-array transducer within three days of cardiac catheterization and compared our results with those obtained by the thermodilution technique and biplane cineventriculography. Heart rate and stroke volume were significantly different among the three techniques: cineventriculography yielded the highest values. These findings suggest that patients may have been in a hyperadrenergic state caused by anxiety experienced during invasive cineventriculography and thermodilution examinations. Inter- and intraobserver variabilities for echocardiography differed little from the variability in cineventriculography. Although there were good correlations between echocardiographic and cineventriculographic findings for EDV (r = 0.67), ESV (r = 0.80), and EF (r = 0.78) by two independent observers, there was a lack of agreement for EDV, ESV, and EF. Echocardiographic EDV values were significantly lower than cineventriculographic values. When left ventricular function is good, the left ventricle tends to be hyperadrenergic and in a more hyperdynamic state with smaller ESV than echocardiographic values during cineventriculography. When left ventricular function is poor, the left ventricle tends to be influenced by the effect of the contrast medium and stress during the invasive examinations and in a more hypodynamic state with larger ESV than echocardiographic values during cineventriculography. The echocardiography is highly reproducible and may provide information that is not available from cineventriculography and thermodilution. Cineventriculography may provide another manifestation of cardiac reserve. In conclusion, we must take into account each peculiar property of the echocardiography, the cineventriculography, or the thermodilution technique when patients are examined with cardiac conditions by different methods at different days.

Adult↗
PubMedDate not supplied

Phase-velocity cine magnetic resonance imaging measurement of pulsatile blood flow in children and young adults: in vitro and in vivo validation.

Quantification of blood flow in vessels provides valuable information that aids management decisions in a variety of cardiac conditions. Current flow measurement techniques are often limited by accuracy, time resolution, convenience, or anatomic localization. This study examined the accuracy of a commercially available phase-velocity cine magnetic resonance imaging (PVC MRI) technique to quantify flow rate in a pulsatile flow phantom. In addition, the equivalence of PVC MRI measurements of pulmonary and systemic flow was evaluated in children and adults without any pathologic shunt. Using a pulsatile flow phantom, volume flow rates measured by PVC MRI were compared to those by a transit-time ultrasound flowmeter over a range of flow rates (1.25-3.5 L/min, 13 trials). Close agreement was found between these techniques (y = 1.02x - 0.02, r = 0.99, Bland-Altman bias = -0.045 L/min, 95% limits of agreement = -0. 19-0.10 L/min). Twenty subjects (median age 12.8 years, range 0.7-49 years) with no pathologic shunt underwent PVC MRI measurement of blood flow in the main pulmonary artery (Q(p)) and the ascending aorta (Q(s)). Data processing time for each location was 20 minutes. The Q(p)/Q(s) ratio closely approximated unity (mean = 0.99, SD = 0. 10, range 0.85-1.19). Interobserver agreement was excellent (Bland-Altman bias = 0.09 L/min, 95% limits of agreement = 0.15-0.33 L/min). PVC MRI is an accurate technique to quantify pulsatile blood flow at a specific location. It can be used to noninvasively calculate Q(p) and Q(s) under normal flow conditions.

Adolescent↗
PubMed2002

Electrocardiographic potential correlations: rationale and basis for lead selection and ECG estimation.

Einthoven gave to us the electrocardiogram. Electrocardiographic mapping demonstrated that localized electrophysiological events and phenomena have localized body surface electrocardiographic manifestations. Clinical electrocardiography has given us "reasonably good" means (criteria) with which to detect and characterize medically significant cardiac conditions, events, and diseases. However, clinical electrocardiography is imperfect, largely as a consequence of inadequate or redundant spatial sampling. This compromises the sensitivity and specificity of diagnosing cardiac diseases for which electrocardiographic manifestations are present but undetected due to imperfect sampling that results in a low signal-to-noise ratio for the specific abnormality. Correlation structure of body-surface potential distributions between and across populations or individuals provides important insight into and justification for the selection and use of "limited", "reduced", or "derived" lead systems aimed at improving the capture and use of electrocardiographic information. In this paper, we show the electrocardiographic voltage correlation relationships that occur on the body surface, across groups of subjects, either with or without cardiac disease. In addition, we demonstrate the correlation relationships between torso-surface and epicardial-surface potential distributions in experiments incorporating isolated canine hearts in a human-shaped torso tank. Analysis of these correlation relationships provides an explanation for the long-standing success of clinical electrocardiography but also suggests the means to improve its performance by incorporating new leads and/or their estimation from appropriately selected leads.

Body Surface Potential Mapping↗
PubMed1976

The relative importance of the major risk factors in atherosclerotic and other diseases.

Examination of results from the Framingham study shows considerable disparity between the various clinical conditions which are grouped together as atherosclerotic diseases in their relationship to systolic blood pressure, serum cholesterol level and cigarette smoking. The outstanding features are the dominance of blood pressure in cerebral conditions and the apparent unimportance of smoking in angina pectoris. Analysis of results from the National Co-operative Pooling Project shows that up to 70% of cardiac conditions in this category may be related to these three risk factors with each being of approximately equal importance. Further evidence suggesting that these factors are of greater importance than is commonly realised for non-cardiovascular deaths has been derived from results in the Chicago Peoples Gas Company Study. Though not conclusive, it is hoped that this analysis adds perspective to considerations of pathogenesis and prevention.

Adult↗
PubMed2006

Effects of high-altitude exercise training on contractile function of rat skinned cardiomyocyte.

OBJECTIVE: Previous studies have questioned whether there is an improved cardiac function after high-altitude training. Accordingly, the present study was designed specifically to test whether this apparent blunted response of the whole heart to training can be accounted for by altered mechanical properties at the cellular level. METHODS: Adult rats were trained for 5 weeks under normoxic (N, NT for sedentary and trained animals, respectively) or hypobaric hypoxic (H, HT) conditions. Cardiac morphology and function were evaluated by echocardiography. Calcium Ca2+ sensitivity of the contractile machinery was estimated in skinned cardiomyocytes isolated from the left ventricular (LV) sub-epicardium (Epi) and sub-endocardium (Endo) at short and long sarcomere lengths (SL). RESULTS: Cardiac remodelling was harmonious (increase in wall thickness with chamber dilatation) in NT rats and disharmonious (hypertrophy without chamber dilatation) in HT rats. Contrary to NT rats, HT rats did not exhibit enhancement in global cardiac performance evaluated by echocardiography. Stretch- dependent Ca2+ sensitization of the myofilaments (cellular index of the Frank-Starling mechanism) increased from Epi to Endo in N rats. Training in normoxic conditions further increased this stretch-dependent Ca2+ sensitization. Chronic hypoxia did not significantly affect myofibrilar Ca2+ sensitivity. In contrast, high-altitude training decreased Ca2+ sensitivity of the myofilaments at both SL, mostly in Endo cells, resulting in a loss of the transmural gradient of the stretch-dependent Ca2+ sensitization. Expression of myosin heavy chain isoforms was affected both by training and chronic hypoxia but did not correlate with mechanical data. CONCLUSIONS: Training at sea level increased the transmural gradient of stretch-dependent Ca2+ sensitization of the myofilaments, accounting for an improved Frank-Starling mechanism. High-altitude training depressed myofilament response to Ca2+, especially in the Endo layer. This led to a reduction in this transmural gradient that may contribute to the lack of improvement in LV function via the Frank-Starling mechanism.

Actin Cytoskeleton↗
PubMed1996

Mitral flow velocity changes after 6 months of optimized therapy provide important hemodynamic and prognostic information in patients with chronic heart failure.

Transmitral flow velocity patterns evaluated by Doppler echocardiography provide important hemodynamic and prognostic information in various cardiac conditions. However, these patterns may change over time, and so far the hemodynamic and prognostic significance of these changes has not been established. Accordingly, we performed this study to determine the hemodynamic and prognostic value of changes in transmitral flow velocity patterns after 6 months of optimized medical treatment in patients with chronic heart failure due to ischemic or nonischemic dilated cardiomyopathy. Ninety-eight consecutive patients with chronic heart failure underwent a clinical examination, a cardiopulmonary exercise test, and simultaneous Doppler echocardiographic and hemodynamic studies at baseline and after 6 months, patients were followed up for 12 +/- 7 months. Cardiac death and heart transplantation while patients were in critical condition were considered events. A restrictive pattern was defined by an early-to-late peak diastolic velocity ratio > 1 and an early diastolic deceleration time < or = 130 msec. Patients were grouped according to their mitral flow pattern at baseline and its changes after chronic optimized therapy. No significant changes in clinical, ergometric, and hemodynamic variables were found after 6 months in the 49 patients who had a persistent restrictive transmitral flow pattern or the 24 patients who had a persistent nonrestrictive transmitral flow pattern. In the 19 patients who had a restrictive pattern at baseline that reverted into a nonrestrictive pattern, this change was accompanied by a highly significant reduction in pulmonary wedge pressure (from 25 +/- 7 mm Hg to 11 +/- 3 mm Hg) and by an increase in exercise capacity, whereas in the 6 patients who had a nonrestrictive pattern that became restrictive, hemodynamic features markedly deteriorated. Seventeen of the 21 events occurred in the 49 patients (event rate 35%) with a persistent restrictive pattern, whereas the event rate was much lower in the 19 patients with a reversible restrictive pattern (5%) and in the 24 patients with a persistent nonrestrictive pattern (4%). Two (33%) of the 6 patients in whom a restrictive pattern developed had events. Cox analysis revealed that a restrictive transmitral flow pattern (p = 0.0068) and peak rate of oxygen consumption (p = 0.0056) detected at the late examination were significantly related to cardiac events. These results show that in patients with chronic heart failure, changes in transmitral flow patterns after chronic optimized therapy are correlated with changes in pulmonary wedge pressure, are accompanied by changes in functional capacity, and provide relevant independent prognostic information.

Blood Flow Velocity↗
PubMed2002

Early onset of cardiomyopathy in two brothers with X-linked Emery-Dreifuss muscular dystrophy.

Two brothers are reported suffering from X-linked Emery-Dreifuss muscular dystrophy caused by a 59bp deletion eliminating nucleotides 329-388 of the STA gene. Besides the typical findings for Emery-Dreifuss muscular dystrophy, both patients showed an unusual early onset of cardiac symptoms at age 6 and 9 years, respectively, coinciding with unusual high creatine kinase. A cardiological follow up showed worsening of the cardiac condition in the beginning of the second decade. The two boys described here belong to the very few Emery-Dreifuss muscular dystrophy patients with early onset of cardiac involvement and contribute to the variability of cardiac symptoms in Emery-Dreifuss muscular dystrophy.

Achilles Tendon↗
PubMed1990

Echocardiographic evaluation of fetal arrhythmias.

When during routine prenatal care, the auscultation++ of the fetal heart beat reveals an abnormal rate or rhythm, two things are needed: 1) the accurate diagnosis of the arrhythmia, and 2) the hemodynamic impact of the rhythm disturbance on the fetus. In Poland, external cardiotocography is the most widely Supported in part by the American Heart Association, Delaware Affiliate, Grant = 41161 available diagnostic system used by obstetricians, but it records only the mean heart rate or the instantaneous heart rate. Cardiotocography is therefore useful only in identifying tachycardia or bradycardia. The most frequent tape of fetal arrhythmia is an irregular rhythm, especially premature contractions (1, 15, 18). We believe that any disturbance in fetal cardiac condition should be evaluated more fully by fetal echocardiography.

Arrhythmias, Cardiac↗
PubMed2006

Implantable cardiac arrhythmia devices--Part II: implantable cardioverter defibrillators and implantable loop recorders.

Implantable cardiac devices have become firmly entrenched as important therapeutic tools for a variety of cardiac conditions. The second part of this two-part review discusses the contemporary use and follow-up of implantable cardioverter defibrillators (ICD) and the implantable loop recorder. The ICD has become the standard therapy for protecting patients against sudden cardiac death. Two recent trials, the Multicenter Automatic Defibrillator Trial II (MADIT II) and the Sudden Cardiac Death Heart Failure Trial (SCD-HEFT), demonstrated that the ICD is associated with a significant survival benefit for patients with reduced ejection fraction (< 0.30-0.35), particularly if heart failure symptoms are present. The ICD has an important role in the management of other conditions associated with a high risk for sudden death, such as hypertrophic cardiomyopathy, long QT syndrome, and Brugada syndrome. The implantable loop recorder has become an important diagnostic tool for the patient with unexplained syncope.

Arrhythmias, Cardiac↗
PubMed2000

Tissue-specific corticosteroidogenesis in the rat.

The steroid aldosterone plays a major role in the maintenance of total body sodium homeostasis and also contributes to cardiovascular pathophysiology by mediating cardiac hypertrophy and fibrosis. In addition to classical adrenal production of aldosterone, endogenous tissue production of aldosterone has been observed in various organs; aldosterone biosynthesis in cardiac tissues, however, remains highly controversial. The current study provides a comprehensive evaluation of steroid hormone biosynthethic capabilities in multiple tissues from two distinct rat strains under unstimulated and stimulated conditions. Panels of tissues from Wistar and Sprague-Dawley rats were probed for 11 beta-hydroxylase (P45011beta) and aldosterone synthase (P450aldo) by reverse transcriptase-polymerase chain reaction (RT-PCR). Under unstimulated conditions, cardiac P45011beta and P450aldo were detected only in Wistar rats. Angiotensin II (100 microg/day) stimulated myocardial expression of both enzymes in both strains. Cerebral cortex and mesenteric artery message levels in both strains was reduced by angiotensin II. These data demonstrate the potential for local steroid synthesis in vascular, cardiac, renal, and neuronal tissues, and that biosynthesis of non-adrenal aldosterone may be differentially regulated between strains. This variability may thus resolve in part or whole the current controversy over the existence of non-adrenal steroidogenic systems.

Adrenal Cortex Hormones↗