Effect of increased inspired oxygen concentrations on exercise capacity in stable heart failure.
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Biomedical subjects
Publications and source records attributed to D Sharif.
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OBJECTIVES: To investigate the occurrence of nocturnal ischemic events in patients with obstructive sleep apnea syndrome (OSAS) and ischemic heart disease (IHD). BACKGROUND: Although previous reports documented nocturnal cardiac ischemic events among OSAS patients, the exact association between obstructive apneas and ischemia is not yet clear. It is also not known what differentiates between patients showing nocturnal ischemia and those that do not. METHODS: Fifty-one sleep apnea patients (age 61.3+/-8.3) with IHD participated in the study (after withdrawal of beta-adrenergic blocking agents and anti-anginotic treatment). All patients underwent whole-night polysomnography including ambulatory blood pressure recordings (30 min interval) and continuous Holter monitoring during sleep. A control group of 17 OSAS patients free from IHD were also similarly studied. Fifteen of the 51 patients were also recorded under continuous positive airway pressure (CPAP). RESULTS: Nocturnal ST segment depression occurred in 10 patients (a total of 15 events, 182 min), of whom six also had morning ischemia (06-08 am). Five additional patients had only morning ischemia. No ischemic events occurred in the control group. Age, sleep efficiency, oxygen desaturation, IHD severity and nocturnal-double product (DP) values were the main variables that significantly differentiated between patients who had ischemic events during sleep and those who did not. Nocturnal ischemia predominantly occurred during the rebreathing phase of the obstructive apneas, and it is characterized by increased heart rate (HR) and DP values. Treatment with continuous positive airway pressure significantly ameliorated the nocturnal ST depression time from 78 min to 33 min (p<0.001) as well as the maximal DP values (14,137+/-2,827 vs. 12,083+/-2,933, p<0.001). CONCLUSIONS: Exacerbation of ischemic events during sleep in OSAS may be explained by the combination of increased myocardial oxygen consumption as indicated by increased DP values and decreased oxygen supply due to oxygen desaturation with peak hemodynamic changes during the rebreathing phase of the obstructive apnea. Treatment with CPAP ameliorated the nocturnal ischemia.
To evaluate the effects of low altitude on exercise performance and myocardial ischemia, 12 patients with coronary artery disease and 6 normal controls underwent ergometric and exercise echocardiography in Haifa, 130 m above sea level, and at the Dead Sea, 402 m below sea level. At the Dead Sea, exercise duration increased by 15% (p <0.05) in the patient and control groups and wall motion score index was improved in patients at rest and after exercise, indicating that descent to the Dead Sea in patients with coronary disease is safe, improves exercise performance, and decreases ischemia.
Cerebrovascular events have high mortality and morbidity, especially in the elderly. Ischemia is the main cause and 30% of the ischemic events are embolic and of cardiac origin. The clinical picture is not always typical of the type of stroke, but diagnosis of the mechanism of the event determines treatment. Transesophageal echocardiography (TEE) is a sensitive procedure more appropriate for diagnosing emboli of cardiac origin than transthoracic echocardiography (TTE). We therefore compared TEE and TTE in the determination of the source of emboli in 65 patients with ischemic stroke but without significant atherosclerotic changes in their carotid arteries, and compared these findings with those in 50 patients without stroke. 68% of the patients had potential sources of emboli according to TEE, compared to only 15% according to TTE. In the control group only 24% had potential sources of emboli by TEE. The findings were: clots in the left atrium, severe aortic atheroma, patent foramen ovale with paradoxical shunt, spontaneous echocardiography contrast, vegetations and mitral valve prolapse. The study showed that TEE is better than TTE in detecting the etiology of embolic stroke in those with normal carotid arteries, thus determining appropriate management.
Hypertrophy of the left ventricle may be associated with altered left ventricular filling dynamics. To test whether isometric and isotonic training affect left ventricular filling differently at rest and during isometric stress, 38 males, 13 long distance runners, eight weight-lifters, eight hypertensive patients and nine age-matched healthy male controls with a mean age of 30 +/- 7 years, were studied before and after 90 s of 50% maximal handgrip force. Left ventricular Doppler filling parameters were compared in the four groups while they were resting and during isometric stress testing, and the results assessed in relation to left ventricular mass index and wall stress. All subjects had normal resting filling patterns except for hypertensive patients, and peak meridional wall stress was low in both athletic groups at rest. Weight-lifters had a hypertensive response during isometric stress testing, associated with a reduction in peak E velocity and a marked increase in peak A velocity, resembling the filling pattern in hypertensive subjects. In runners the filling pattern remained normal. Thus, while the resting left ventricular pattern was normal in all athletes, isometric stress testing was associated with a hypertensive filling pattern only in weight-lifters compared to normal filling in runners.
Progressive shortness of breath developed in an elderly woman with a 25-year history of recurrent superficial phlebitis and hemoptysis. Extensive mural thrombosis and ectasia of the large and medium-sized pulmonary arteries and aorta were revealed on echocardiography and computerized tomography. The patient died 2 months later. On autopsy, the gross morphologic findings were similar with those observed by imaging. Histologically, there was mild inflammation in the intima and media of the aorta and the large pulmonary arteries, consistent with nonspecific arteritis. The extensive thrombosis and ectasia of the pulmonary arteries and aorta differ from previously published cases and cannot be assigned to a known nosologic entity. Two alternative explanations are proposed. First, an endothelial disorder was responsible for a diffuse vasculopathy that involved veins, pulmonary arteries, and aorta. Second, a vasculopathy of the Hugh-Stovin type, characterized by phlebitis and pulmonary thromboembolism, caused pulmonary hypertension and low cardiac output. The low flow state favorized aortic thrombosis and, at the site of interaction between the clot and the arterial wall, arteritis developed as an epiphenomenon, which induced arterial dilatation. Combined idiopathic pulmonary artery and aortic thrombosis and ectasia is rare and calls for corroboration of sporadic observations such as the current one.
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Pulsed Doppler echocardiography allows simultaneous recording of left ventricular inflow and outflow blood velocities obtained from the apical 5-chamber view. In this study the feasibility and accuracy of pulsed Doppler measurements of left ventricular isovolumic relaxation and contraction times were compared with those derived from two conventional techniques that combined phonocardiograms and M-mode echograms (phono-echo) and M-mode echograms and electrocardiograms (ECG-echo). Thirty-seven subjects--24 healthy volunteers and 13 cardiac patients--were examined. Isovolumic relaxation was consistently longer than isovolumic contraction time. Younger age was associated with shorter isovolumic intervals, while heart rate had a negative correlation with these parameters (r = -0.5). Pulsed Doppler measurements of isovolumic relaxation correlated well with phono-echo, r = 0.89, and ECG-echo, r = 0.75. Isovolumic contraction times measured by Doppler correlated better with those derived by phono-echo, r = 0.75, than those by ECG-echo, r = 0.4. Better correlations were found for both measurements in the normal subgroup than in the whole group. Difficulty was encountered in measuring isovolumic contraction time by Doppler and ECG-echo in the absence of presystolic A-wave, and in subjects with varying cardiac cycle lengths. Thus, pulsed Doppler measurements of left ventricular isovolumic relaxation times were feasible and consistent with the other methods, while isovolumic contraction intervals by Doppler were not.
Fetal echocardiography is an ultrasonic technique for the diagnosis of cardiac defects and fetal arrhythmias. During 1981-1990 we examined 1800 women referred for elective examinations from all over the country. Most, at high risk for fetal cardiac anomalies, were examined in the 22nd week of gestation. Others were examined whenever a fetal arrhythmia or a cardiac defect was suspected. In 251 fetuses (13.9%) pathological cardiac conditions were found, and structural heart defects in 51 (2.8%). When a cardiac defect with poor prognosis was diagnosed during the 2nd trimester, termination of pregnancy was suggested. In 35% of these cases termination of pregnancy was accepted. In 12% of the women examined spontaneous intra-uterine fetal death had occurred, while in 52% live babies were born, but half died within 6 months. In 215 fetuses (11.9%) a cardiac arrhythmia was found, which in 73% consisted of supraventricular premature beats. In 15.8% the fetus was endangered by the arrhythmia, mainly supraventricular tachycardia, atrial fibrillation or atrial flutter. Treatment was by drugs administered to the mother. In 1 case of complete A-V block echocardiographic follow-up demonstrated rapid deterioration of heart function. Delivery was induced and a pacemaker was implanted in the newborn.
Doppler interrogation at the in-flow of the left ventricle was used to test the effects of isometric stress on ventricular filling in 7 hypertensive subjects with mild to moderate left ventricular hypertrophy, aged forty-two +/- seven years, compared with 9 matched healthy control males. In the hypertensive patients at rest, peak early diastolic (E) velocity was lower, and atrial (A) velocity higher, with lower E/A peak velocity ratios than in normals (p less than 0.05). These differences were more accentuated during isometric stress. Atrial filling fractions were higher in hypertensives (37 +/- 6%) than in normals (24 +/- 7%) at rest, p less than 0.05, and this difference increased during isometric stress (44 +/- 9% versus 30 +/- 11%). Thus, isometric stress accentuated the reliance of left ventricular filling on atrial contribution and may be applied for the detection of early ventricular filling abnormalities in patients with mild hypertension. The systolic blood pressure and the hypertrophic process were both important determinants of left ventricular diastolic filling.
The clinical records of 339 consecutive patients who had received temporary transvenous pacemakers were analyzed for indications, complications and malfunctions. Of the 156 patients who had had an acute myocardial infarction (AMI), 50% had had anterior wall and 43.6% inferior wall involvement. The route of electrode insertion was the antecubital vein in 71%, subclavian vein in 24%, internal jugular vein in 4%, and a femoral vein in the remainder. The indication for pacing in the AMI group was atrioventricular (A-V) block in 55%, fascicular block in 32% and other arrhythmias in 13% of the cases. In the non-AMI group, the indication for pacing was A-V block in 46.4%, sick sinus syndrome in 25%, preparation for noncardiac surgery in 12%, and diagnostic purposes in the remainder. Ventricular fibrillation (VF) occurred only in the AMI group and appeared in 9 (5.66%) of these cases. The site of infarction did not significantly affect the incidence of VF. Ventricular premature beats (VPBs) and ventricular tachycardia (VT) appeared in 28.8 and 12.8% of the AMI group and 4.4 and 3.3% of the non-AMI group, respectively. No difference in the incidence of myocardial perforation, sepsis, and phlebitis was encountered between the AMI and non-AMI groups. Total malfunction rate was significantly higher in the AMI group (15%) vs. the non-AMI group (4%). A higher rate of pacing malfunction was found when a semifloating electrode was used through the subclavian vein (14.3%) vs. a 6 or 7 French electrode through the antecubital vein (7%). Thus, temporary pacing is safe and associated with lower incidence of complications and malfunctions in non-AMI than in AMI subjects. Moreover, a lower incidence of malfunction was encountered when a 6 or 7 French electrode was inserted through the antecubital vein.
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10 patients suffering from refractory heart failure were treated with an oral angiotensin converting enzyme inhibitor captopril. The etiology of heart failure in 9 patients was related to ischemic heart disease, and to valvular heart disease in 1 patient. All patients experienced subjective improvement and feeling of well-being. The functional capacity improved to class II-IIB. Serial chest X-ray films showed improvement in pulmonary congestion. The time course of the hemodynamic effect appeared to 0.5-1.5 h after intake, and tended to disappear about 6 h later. The optimal dose of the drug achieving maximal hemodynamic benefit without excessive hypotension was 50 mg. Some of the patients exhibited a triphasic response. The cardiac index increased from 1.99 +/- 0.1 to 2.69 +/- 0.151/min/m (p less than 0.001), while pulmonary capillary wedge pressure decreased from 25.3 +/- 5.86 to 13.67 +/- 4.14 mm Hg (p less than 0.001). Mean peripheral arterial blood pressure decreased from 90.06 +/- 3.7 to 71.4 +/- 2.7 mm Hg. The total peripheral resistance decreased from 1,942 +/- 169 to 1,170 +/- 109 dyn X s X cm-5. The total pulmonary resistance decreased from 272.6 +/- 42.9 to 142.34 +/- 13.76 dyn X s X cm-5. Heart rate decreased from 83.4 +/- 10.9 to 70.8 +/- 10.14 bpm (p less than 0.01). During a 6-month follow-up period the beneficial clinical effects of captopril were sustained, without late vasodilator tolerance. 1 death, unrelated to captopril, occurred. 2 patients developed transient rash, and 1 experienced transient dysgeusia.
Podagra is a term used to describe acute monoarthritis of the first metatarsophalangeal (1st MTP) joint. The most common diagnoses of arthritis in this joint are: crystal-induced synovitis, septic arthritis, traumatic conditions and reactive arthritis. When etiologies other than gout are involved this is frequently referred to as pseudopodagra. We report the case of a patient who presented with pain and swelling of the 1st MTP The absence of intraarticular crystals and hyperuricemia encouraged further evaluation of the patient. A cardiac murmur was investigated by echocardiography, which revealed valvular vegetations and the diagnosis of infective endocarditis (IE) was established. This is the first reported case of a podagra-like presentation of IE. As in this case, the diagnosis of gout should rest on findings beyond the presence at 1st MTP arthritis, with evaluation of all extraarticular signs in order to rule out other possible diagnoses.