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Biomedical subjects

D Tzivoni

Publications and source records attributed to D Tzivoni.

At least 109 records · Page 6Linked to original sources
PubMed1984

Early right atrial pacing after myocardial infarction. II. Results in 77 patients with predischarge angina pectoris, congestive heart failure, or age older than 70 years.

Seventy-seven consecutive postinfarction patients who had either predischarge angina pectoris or congestive heart failure, or who were older than 70 years of age, underwent right atrial (RA) pacing before hospital discharge. In 60% of these patients, ischemic changes developed during RA pacing; this high yield of positive response indicates advanced coronary arterial disease. During a mean follow-up of 15 months, these patients had a high mortality rate (18%) and a reinfarction rate of 9%. RA pacing separated this a priori high-risk group into lower- and higher-risk subsets. Of the 46 patients with a positive RA pacing response, 6 had reinfarction, while none of the 31 patients with a negative RA pacing response had reinfarction (p = 0.04); 10 of the 14 cardiac deaths were among the patients who had positive RA pacing responses at discharge (p = not significant). Thus, of the 20 major cardiac events, 16 occurred among those with positive RA pacing responses (p less than 0.05). Predischarge clinical symptoms, however, were not good predictors of subsequent major cardiac events. We conclude that RA pacing can be safely performed even in high-risk and elderly patients and a positive response can identify those who have a poorer prognosis. Therefore, for postinfarction patients who, according to the prevailing criteria, are excluded from treadmill testing, we advocate the use of RA pacing.

Adult↗
PubMed1984

Magnesium therapy for torsades de pointes.

This is the first report of the successful use of magnesium sulfate (MgSO4) in 3 consecutive patients with torsades de pointes (TdP). In 1 patient, TdP was induced by a combination of quinidine and amiodarone, in the second by procainamide, and in the third by an overdose of imipramine. The QT intervals before TdP were 0.70, 0.64 and 0.56 second, respectively. A bolus of 1.0 to 2.0 g MgSO4 25% abolished the TdP in all 3 patients; but in the third patient, because of recurrent TdP, a second bolus of 1.0 g and a continuous 24-hour infusion of 1.0 mg/min were administered, preventing TdP. There was no immediate shortening in the QT interval in any patient after MgSO4. Magnesium can be given safely even in patients with acute myocardial infarction, angina pectoris or systemic hypertension, conditions in which isoproterenol is contraindicated; it can be applied faster than temporary cardiac pacing; and its use for TdP appears worthy of additional trials.

Aged↗
PubMed1983

Prazosin therapy for refractory variant angina.

The selective alpha, blocker prazosin was used to abolish Prinzmetal's variant angina in six patients. All had had an acute transmural myocardial infarction, after which the anginal attacks with transient ST segment elevation developed, and three of them had already suffered from variant angina prior to the infarction. Therapeutic trials with high doses of nifedipine, verapamil, nitrates, beta blockers, and (in one case) phenoxybenzamine were ineffective in all six patients. Prazosin, 8 to 30 mg/day combined with low-dose nitrates or nifedipine completely abolished the attacks in four patients, markedly reduced their frequency and intensity in one patient, and had to be stopped in the sixth one because of hypotension and dizziness. Except for this last patient, the drug was well tolerated by all the others, and no changes in blood pressure were observed. In four patients discontinuation or reduction of prazosin resulted in exacerbation of symptoms, but its renewal was followed by disappearance of the attacks. Since the mean follow-up period in this study was 4 to 6 months, further evaluation appears necessary concerning the long-term effects of this drug in Prinzmetal's variant angina.

Aged↗
PubMed1983

Effect of exercise on cerebral circulation.

The effect of supine physical exercise on cerebral blood flow (CBF) was measured in 30 normal subjects with the 133Xe inhalation technique. The CBF measurements were correlated to changes in PCO2, heart rate, and blood pressure, and to cardiac output and right atrial pressure in 10 of the subjects who underwent Swan-Ganz catheterization. No significant change was found in CBF during physical exercise, although a marked increase in cardiac output, blood pressure, and right atrial pressure and a mild decrease in PCO2 were found. Cerebrovascular resistance increased by 38%, in contrast to a decrease of 33% in the peripheral vascular resistance. The factors that affect the mechanism of cerebrovascular autoregulation during exercise are discussed.

Adult↗
PubMed1983

Exercise-induced S-T segment elevation in variant angina.

3 patients with co-existing effort angina and Prinzmetal's variant angina are described, who had also 'atypical' manifestations of variant angina, i.e. chest pain and S-T segment elevation also during treadmill exercise testing. Because of these unusual manifestations the proper diagnosis was delayed and the patients continued with inappropriate therapy (propranolol and only low-dose nitrates). After the correct diagnosis of variant angina with 'atypical' manifestations was made, application of high-dose nitrates and nifedipine resulted in complete relief of symptoms. Repeat treadmill testing during this therapy did not provoke attacks of chest pain with S-T elevation.

Angina Pectoris, Variant↗
PubMed1983

Atrial pacing thallium scintigraphy in the evaluation of coronary artery disease.

A study was undertaken to examine the value of rapid atrial pacing and thallium-201 scintigraphy in the evaluation of ischemic heart disease. Ten subjects with angiographically normal coronary arteries and 31 patients with coronary artery disease were studied. Six of these patients were studied after coronary artery bypass surgery. Coronary ischemia or infarction could be diagnosed from the ECG alone (rest and atrial pacing) in 87% of the patients with a greater than or equal to 50% narrowing of a coronary artery. The ECG and scintiscan (at rest and pacing) together had a sensitivity of 100%. The ECG could not identify the site of stress-induced ischemia. Rapid atrial pacing with scintigraphy identified 91% of those patients with a right coronary artery narrowing (greater than 50%), 85% with a narrowing of the left anterior descending coronary artery, but only 33% with a narrowing of the circumflex coronary artery. The scintiscan correctly identified 40% of arteries with a 50 to 89% narrowing, 75% with a 90 to 99% narrowing and 88% with a complete obstruction. The scintiscan predicted single- and double-vessel disease, but underestimated the number of vessels involved in patients with triple-vessel disease. This technique was also useful in assessing the patency of implanted coronary artery bypass grafts. Rapid atrial pacing is a simple and safe method of inducing ischemia, while thallium scintigraphy shows the site, extent and severity of coronary artery disease.

Adult↗
PubMed1983

Nuclear left ventriculography at rest and during atrial pacing in the evaluation of coronary artery disease.

This study was undertaken to examine the value of rapid atrial pacing (RAP) combined with left-ventricular nuclear (LVN) angiography in the diagnosis of ischemic heart disease. It included 32 patients: 12 normal subjects and 20 with clinical coronary artery disease (CAD) and greater than 50% narrowing of a coronary artery (significant CAD). The ECG and an LVN angiogram (LVNA) were recorded at rest and during graded RAP. In the normal subjects, left-ventricular wall motion was normal at rest and during atrial pacing, but a wall motion abnormality (WMA) appeared in one subject. Left-ventricular ejection fraction (EF) did not change significantly. In the 20 patients with significant CAD, the diagnostic sensitivity of the ECG during RAP was 100% and 90% for the nuclear angiogram (presence or appearance of WMA at rest and during RAP). The mean EF in this group decreased from 0.38 to 0.31. WMA on the LVNA was present in 79% of patients with significant left-anterior descending, in 44% of those with right, and in 33% of those with circumflex coronary artery disease. WMA (at rest or on pacing) occurred in 17% of patients with 50 to 89% narrowing of an artery, in 50% with 90 to 99% narrowing and in 68% with total obstructions. The LVNA (rest and/or RAP) identified patients with significant single-vessel disease, but underestimated the extent of double-and triple-vessel disease. The LVNA at rest and during atrial pacing was an excellent method of evaluating significant coronary artery disease.

Adult↗
PubMed1982

Origin of both coronary arteries from the same sinus of Valsalva: report of two cases.

Origin of both coronary arteries from the same sinus of Valsalva was found in two patients. In one patient the right coronary artery opened from the left sinus of Valsalva, coursed between the pulmonary artery and aorta, disclosed a 95% obstruction in its proximal third with good runoff. The portion of the artery between the aorta and pulmonary artery showed cyclic narrowing during systole. In the second patient the left coronary opened from the right sinus of Valsalva, the left main trunk crossed anteriorily the pulmonary artery conus, and both the circumflex and the left anterior descending branches showed significant narrowing. In both patients the arteries shared a common sinus with two separate orifices, both had bicuspid aortic valve, and in both, nonaberrant coronary vessels also had stigmata of atherosclerosis.

Aged↗
PubMed1982

Comparison of right atrial pacing soon after myocardial infarction with treadmill testing 6 months later.

Seventy-four patients recovering from acute myocardial infarction underwent right atrial pacing before hospital discharge, and treadmill exercise testing 6 months later. The early right atrial pacing test was positive in 32 patients (43 percent) and the late treadmill test was positive in 32 patients (42 percent). The results of the two tests were concordant in 77 percent of the patients, 23 with an ischemic response and 34 with a normal response on both tests. In nine patients a positive right atrial pacing test was followed by a negative treadmill test, and in eight patients a negative pacing test was followed by a positive treadmill test. A positive right atrial pacing test at hospital discharge had an 81.0 percent predictive accuracy for a positive late treadmill test; chest pain, congestive heart failure or increased cardiothoracic ratio at discharge had a predictive value of only 52.9, 42.8 and 42.8 percent, respectively. Both the early right atrial pacing test and the late treadmill test were positive in a significantly higher proportion of patients with inferior or subendocardial infarction than of patients with anterior myocardial infarction. During early right atrial pacing the mean maximal heart rate achieved was higher than that during late treadmill testing (148 versus 133 beats/min) and the mean systolic blood pressure was lower (137 versus 162 mm Hg), but the pressure-rate product was similar on the two tests (20,282 versus 21,455 mm Hg/min). This finding may explain the similar frequency of ischemic responses to the two tests. These results indicate that the response to right atrial pacing soon after myocardial infarction is a good predictor for the presence or absence of an ischemic response to treadmill testing 6 months later. Thus, early right atrial pacing at the time of hospital discharge may be used to determine the pace of rehabilitation and short-term prognosis.

Adult↗