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Biomedical subjects

M A Stefadouros

Publications and source records attributed to M A Stefadouros.

At least 19 recordsLinked to original sources
PubMed1987

Cardiovascular effects of ritodrine tocolysis: a new noninvasive method to measure pulmonary capillary pressure during pregnancy.

The cardiovascular effects of ritodrine tocolytic therapy were assessed by noninvasive simultaneous recordings of indirect carotid pulse, electrocardiogram (ECG), phonocardiogram, and M-mode echocardiogram in 12 patients in preterm labor. The study was performed before and during infusion, and afterward when the patient was on oral drug therapy. Ritodrine therapy increased heart rate, left ventricular fractional shortening, pre-ejection period/left ventricular ejection time ratio, and cardiac index. A progressive rise in pulmonary capillary pressure was observed in all patients, exceeding 18 mmHg (the threshold for the development of pulmonary congestion) in six patients. Systolic arterial pressure, left ventricular end-diastolic dimension, and plasma protein oncotic pressure remained unchanged during therapy. Ritodrine therapy resulted in a significant drop in diastolic blood pressure and peripheral vascular resistance. This noninvasive means of measuring cardiovascular parameters, including pulmonary capillary pressure, may be useful in monitoring patients who develop significant cardiovascular side effects during tocolytic therapy.

Echocardiography↗
PubMed1984

Potentially lethal arrhythmias and their management in hypertrophic cardiomyopathy.

The prevalence of potentially lethal arrhythmias (PLA) in groups of patients with hypertrophic cardiomyopathy has been assessed, but the rate at which they develop (their incidence) during long-term follow-up has not been reported. Therefore, conduction system disease (CSD) (sick sinus syndrome and His-ventricular disease), ventricular couplets and ventricular tachycardia (VT) detected by routine electrocardiograms, periodic 24-hour Holter monitoring and periodic exercise stress testing were studied in 50 patients treated with large doses of beta-adrenergic blocking drugs who were followed for 2 to 14 years (mean 5.9). Sixteen PLAs detected at the beginning of observation were excluded from actuarial analysis for new PLAs . Twenty-one patients had 24 new PLAs (7 with CSD, 1 patient with sustained supraventricular tachycardia, 6 with ventricular couplets and 10 with VT); only 43% of these PLAs were heralded by new symptoms. In 6 patients, the arrhythmia caused symptoms and was identified by a routine electrocardiogram. The 3 patients with His-ventricular disease presented with syncope and required electrophysiologic confirmation of this diagnosis. In only 1 patient was a PLA (ventricular couplets) detected only by exercise testing. All other ventricular arrhythmias were detected by Holter monitoring. The incidence of CSD in 47 patients free of this condition at entry was 5% at 5 years and 33% at 10 years. The incidence of ventricular couplets or VT in 39 patients free of these at entry was 26% at 5 years and 75% at 10 years, and the incidence of VT only was 18% at 5 years and 40% at 10 years.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1983

Value of ventricular premature complex (VPC) morphology in the diagnosis of hypertrophic cardiomyopathy.

Experimental and clinical studies have established the value of ventricular premature complexes (VPC) with a QR pattern in the diagnosis of occult antecedent myocardial infarction. However, the clinical significance of a QR pattern VPC in patients with hypertrophic cardiomyopathy has not been previously evaluated. In order to study this, we examined the ECGs and 24-hour Holter monitor records of 45 consecutive patients with hypertrophic cardiomyopathy and 106 consecutive patients with various other diseases. A QR pattern VPC in the precordial leads with a Q greater than or equal to 40 ms and a Q/R ratio greater than or equal to 0.20 had a specificity of 97%, a sensitivity of 29% and a predictive value of 80% in the diagnosis of hypertrophic cardiomyopathy. We conclude that a QR pattern VPC may be of value in the eclectic diagnosis of hypertrophic cardiomyopathy and that it is not specific for antecedent myocardial infarction as previously reported.

Cardiomyopathy, Hypertrophic↗
PubMed1983

Long-term medical management of hypertrophic cardiomyopathy: usefulness of propranolol.

Chronic therapy with propranolol has been shown to reduce the incidence of sudden death in patients with hypertrophic cardiomyopathy (HCM). However, the long-term effect of beta blockade on exercise capacity has not been studied adequately. Therefore, 32 patients with HCM (21 men), mean age of 47 years (range = 14 to 80 years), were evaluated for dyspnea and chest pain and underwent stress testing (ST) prior to therapy. At entry, ST was contraindicated in four patients, because of heart failure (three patients) and sustained supraventricular tachycardia (one patient). The remaining patients completed 4.9 +/- 3.2 min (mean +/- S.D.) of the Bruce protocol with a functional aerobic capacity (FAC) of 51 +/- 28%. All were placed on propranolol, unless a beta blocker with other characteristics was indicated. Dosage was adjusted to achieve a standing heart rate of 60 beats/min unless adverse effects occurred. At last follow-up, 25 patients were receiving 501 +/- 147 mg propranolol/day while the remainder received nadolol or metoprolol. On the most recent ST, patients exercised 6.6 +/- 3.1 min (38% increase), while mean FAC increased by 24% (both P less than 0.05). The FAC improved by more than 15% in 21, by less than 15% in five, was unchanged in five and was worse in only one, a noncompliant patient. The 21 patients with an FAC increment much greater than 15% exercised longer at entry than the remaining 11 (6.6 +/- 3.3 vs 3.9 +/- 2.8 minutes, P less than 0.05). The mean peak ST blood pressure-heart rate product of the group decreased from 26 550 to 17 898 (P less than 0.05), while the symptom scores of dyspnea and chest pain declined from 2.2 +/- 0.8 to 0.8 +/- 0.7 and from 1.4 +/- 1.0 to 0.3 +/- 0.8, respectively (both P less than 0.001). We conclude that beta blockade produces sustained improvement in exercise capacity. Improvement was greatest in those with the least initial impairment, and appears to be related to a reduction in blood pressure-heart rate product.

Adolescent↗
PubMed1983

Rhythm disturbances in hypertrophic cardiomyopathies: relationship to symptoms and the effect of 'complete' beta blockade.

Potentially lethal arrhythmias (PLA) are common in hypertrophic cardiomyopathies and are implicated in sudden death. We have demonstrated that propranolol is effective in controlling symptoms, but have not previously evaluated its effect on PLA. Our protocol for long-term management has been applied to 50 patients followed for 2 to 14 years (mean 5.9 years). No patient was excluded because of disease severity or complications. The only reason for exclusion was non-compliance with the protocol. At entry, Holter monitoring revealed 16 PLA in 13 patients (sustained supraventricular tachycardia (SSVT) in two, sinus node dysfunction (SSS) in three, paired beats (PB) in five, and ventricular tachycardia (VT) in six). All patients were initially begun on propranolol, unless a different beta blocker was indicated. Dosage was adjusted to a standing heart rate of 60 beats/min unless adverse drug effects developed. Holter monitoring during follow-up identified 24 new PLA in 21 patients (SSVT = 1, SSS = 4, His-Purkinje disease = 3, VT = 10, and PB = 6). The total number of identified PLA is now 40 in 30 patients. Concurrent symptoms of syncope, presyncope and palpitations were of limited value in identifying PLA because of a lack of predictive accuracy (76%, 64% and 29%, respectively). Invasive electrophysiologic study or dosage adjustment proved that beta blockade was not responsible for the conduction system disorders observed in 10 patients requiring pacemaker insertion. beta-Blockade completely suppressed VT in two patients, PB in five, and SSVT in two.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1982

Use of a personal computer in the measurement, calculation, and reporting of noninvasive cardiac data.

Echocardiography, phonocardiography, and carotid pulse tracings enable the cardiologist to measure and calculate over 40 different noninvasive parameters including cardiac chamber size, indices of left ventricular performance, and estimates of mean left atrial pressure. However, the entire procedure requires meticulous measurements and time-consuming calculations, particularly when some of the data must be corrected for heart rate or body size. Because of this, many busy noninvasive cardiac laboratories routinely calculate only a few select parameters in most patients. To solve this problem, we used a personal computer system and developed a program that allows rapid, accurate measurement, calculation, display, reporting, magnetic storage, and retrieval of noninvasive cardiac data. The computer is not dedicated to these tasks alone and with appropriate software can also be used for other clinical, educational, office management, and research purposes.

Computers↗
PubMed1982

Postextrasystolic changes in systolic time intervals in the assessment of hypertrophic cardiomyopathy.

To determine if postextrasystolic changes in systolic time intervals can be used to estimate the severity of resting or provocable left ventricular outflow pressure gradient, we studied the cardiac catheterisation records of 42 patients with hypertrophic cardiomyopathy looking for instances of a single premature beat preceded by a control sinus beat and followed by a postpremature sinus beat. There were 75 such instances in 25 patients. In comparison to the control beat, the pre-ejection period in the postpremature beat was shorter by deltaPEP = -20 +/- 11 ms in 73 of 75 instances, and remained unchanged in two. The ejection time in the postpremature beat was invariably longer by deltaET = 37 +/- 20 ms (range: 10 to 85 ms) and the pre-ejection period/ejection time ratio lower than control by delta(PEP/ET) = -0 . 10 +/- 0 . 05 (range: -0 . 01 to -0 . 25). Total electromechanical systole in the postpremature beat was shorter (11/75), the same (10/75), or longer (53/75) than in the control beat, the overall change being deltaEMS = -18 +/- 22 ms. Both deltaPEP and delta(PEP/ET) correlated poorly with the systolic peak left ventricular-aortic pressure gradient in either the control beat (Gc) or the postpremature beat (Gx), and also with the change in gradient (delta G) from the control to the postpremature beat. In contrast, significant linear correlations were found between delta EMS and either Gc, Gx, or delta G; and also between deltaET and either Gc, Gx, or deltaG. Since internal and external measurements of ejection time are known to be almost identical, the regression equation (deltaG = 1 . 65 delgaET -9) relating deltaET and deltaG should be useful for the non-invasive assessment of the magnitude of provocable left ventricular outflow pressure gradient in patients with hypertrophic cardiomyopathy with spontaneous or externally-induced premature beats.

Blood Pressure↗
PubMed1981

Hypercontractile cardiac state mimicking hypertrophic subaortic stenosis.

Idiopathic hypertrophic subaortic stenosis (IHSS) is a disease manifested as a spectrum of various clinical and laboratory findings. We present the case of a patient with classical clinical and hemodynamic findings of IHSS who lacked all of the typical echocardiographic features of the disease. The case emphasizes the need for diligent use of bedside physical examination and vasoactive manipulation of systolic murmurs whenever functional left ventricular outflow tract obstruction is suspected, since it can occasionally be missed by echocardiography.

Cardiac Catheterization↗
PubMed1981

Determination of systolic time intervals from the first derivative of the indirect brachial arterial pulse.

Technical difficulties occasionally preclude adequate recording of the indirect carotid pulsations needed for measuring the systolic time intervals by the conventional method. Accordingly, in 81 subjects with a wide spectrum of heart diseases, an alternative method was tested based on substituting the first time derivative of the indirect brachial arterial pulse for the carotid pulse. The observed differences between systolic time intervals measured by the two methods were small enough, and their correlation coefficients high enough, to inspire confidence in the use of the proposed method as an alternative way for determining systolic time intervals.

Brachial Artery↗
PubMed1981

A computer program for determining Vmax from the uncalibrated left ventricular pressure signal and its first derivative.

A computer program was developed to simplify the conventional method for determining the maximal contractile element shortening velocity at zero load (Vmax) by analysis of pressure-velocity graphs during the isovolumic contraction period. From an uncalibrated left ventricular (LV) pressure signal and its first derivative (dP/dt), the graph relating developed LV pressure (Pd) to the corresponding instantaneous value of (dP/dt)/28 Pd was constructed by the computer. The segment of the graph that encompassed approximately the second half of the isovolumic contraction period, as determined by analysis of the dP/dt waveform, was then extrapolated to provide V'max on the ordinate. This V'max was compared with the conventional Vmax obtained from calibrated LV and aortic pressure signals. In 5 dogs both in the control state and during inotropic (epinephrine, propranolol) and noninotropic interventions (phenylephrine or dextran infusion), a high degree of correlation was found relating V'max and Vmax both derived by either linear (Vmax = 0.91 V'max + 0.14; r = 0.933; P less than 0.001) or exponential (Vmax = 0.99 V'max - 0.06; r = 0.959; P less than 0.001) extrapolation of the pressure-velocity graph to zero load. By use of this program, Vmax can be easily and reliably estimated from the uncalibrated LV pressure signal and its first derivative.

Animals↗
PubMed1980

Determination of mean pulmonary capillary pressure by a noninvasive technique.

The feasibility of estimating the mean pulmonary capillary pressure (PCP) by simultaneous noninvasive recording of the ECG, phonocardiogram, and mitral valve echocardiogram was tested in 36 patients with miscellaneous heart lesions. The recordings were made in close sequence with direct measurement of PCP by a catheter. The interval from the onset of the QRS complex to the echocardiographic point C of mitral valve closure (Q-C) and the time from the aortic valve closure sound to the E point of the mitral echocardiogram (A2-E) were measured. The difference between these two intervals exhibited a good linear correlation with the PCP. A better correlation was found between the ratio (Q-C)/(A2-E) and the PCP, which is potentially useful in the noninvasive determination of PCP in several forms of heart disease.

Adolescent↗