Antioxidant behaviour of caffeine: efficient scavenging of hydroxyl radicals

Considerable controversy exists in the literature regarding the toxicity of coffee, including its possible carcinogenic and anticarcinogenic properties. This study reports on the reaction of 1,3,7-trimethylxanthine (caffeine) with the hydroxyl radical (.OH), as investigated by electron spin resonance (ESR) spin trapping. The .OH was generated by the Fenton reaction (Fe2+ + H2O2) as well as by the reaction of chromium(V) with H2O2. The results show that caffeine effectively scavenges .OH with a reaction rate constant of approximately 5.9 x 10(9) M-1 sec-1 that is comparable with those of other efficient .OH radical scavengers. ESR measurements provide evidence that a caffeine-derived oxygen-centred radical is formed in the reaction of caffeine with .OH and suggest a biochemical basis for the understanding of the reported anticarcinogenic properties of caffeine and related methylxanthine compounds.

Effect of preoperative statin therapy and cardiac outcomes after coronary artery bypass grafting

Preoperative statin administration in this analysis showed improved cardiovascular outcomes after coronary artery bypass graft surgery, including death, myocardial infarction, unstable angina, and arrhythmias.

Early repolarization

Early repolarization (ER) is an enigma. The purpose of this review is to reemphasize the overall electrocardiographic (ECG) pattern of this normal ST variant which continues to challenge the clinician because of its similarity to the current of injury potential to myocardium or an acute pericarditis. The data were provided from the studies identified through computerized searches of Medline, Toxline, Oxford, Agricola, and Bios Afterdark, Cumulative index, and a review of bibliographies of relevant articles on the related subjects. Early repolarization has elevated, upward, concave ST segments, located commonly in precordial leads, with reciprocal depression in a VR, tall, peaked and slightly asymmetrical T waves with notch, and slur on the R wave. The other accompanying features in the ECG are vertical axis, shorter and depressed P-R interval, abrupt transition, counterclockwise rotation, presence of U waves, and sinus bradycardia. Males dominate and patients are often younger than 50 years of age. The incidence of 1 to 2% is found equally common in all races. Degree and incidence of ST elevation decrease as age advances. Exercise or isoproterenol administration may normalize the ST segment. Early repolarization is a benign condition. If the ECG conforms to a classical pattern of ER on serial ECGs, it would exclude the unnecessary hazards of present day revascularization therapy for myocardial infarction such as primary angioplasty or thrombolytic therapy, or aggressive management of acute pericarditis, and so forth. This review concludes with a discussion of comparative ECG features of ER, pericarditis, and myocardial infarction, and provides an algorithm for diagnostic management of patients suffering from these conditions.

Early repolarization on scalar electrocardiogram

Sixty thousand electrocardiograms were analyzed for 5 years. Six hundred (1%) revealed early repolarization (ER). Features of ER were compared with race-, age-, and sex-matched controls (93.5% were Caucasians, 77% were males, 78.3% were younger than 50 years, and only 3.5% were older than 70). Those with ER had elevated, concave, ST segments in all electrocardiograms (1-5 mv), which were located most commonly in precordial leads (73%), with reciprocal ST depression (50%) in a VR, and notch and slur on R wave (56%). Other results included sinus bradycardia in 22%, shorter and depressed PR interval in 38%, slightly asymmetrical T waves in 96.7%, and U waves in 50%. Sixty patients exercised normalized ST segment and shortened QT interval (83%). In another 60 patients, serial studies for 10 years showed disappearance of ER in 18%, and was seen intermittently in the rest of the patients. The authors conclude that in these patients with ER: 1) male preponderance was found; 2) incidence in Caucasians was as common as in blacks; 3) patients often were younger than 50 years; 4) sinus bradycardia was the most common arrhythmia; 5) the PR interval was short and depressed; 6) the T wave was slightly asymmetrical; 7) exercise normalized ST segment; 8) incidence and degree of ST elevation reduced as age advanced; 9) possible mechanisms of ER are vagotonia, sympathetic stimulation, early repolarization of sub-epicardium, and difference in monophasic action potential observed on the endocardium and epicardium.

Cardiac Arrhythmias Following Intravenous Nicotine: Experimental Study in Dogs

BACKGROUND: Nicotine, the active agent in tobacco, is released into the circulation during cigarette smoking. It elevates plasma catecholamines, heart rate, and arterial blood pressure; produces coronary spasm; and increases myocardial work and oxygen demand with concomitant reduction in oxygen supply. This may generate cardiac arrhythmias that might contribute to an increased incidence of sudden death due to smoking. It is hypothesized that acute administration of nicotine will induce cardiac arrhythmias, and this experimental study was planned with an aim to assess arrhythmogenic activity as a result of acute administration of nicotine. METHODS: Nicotine was administered in different doses intravenously in 16 anesthesized dogs, and 52 experiments were carried out at weekly intervals. In each experiment, continuing anesthesia and after nicotine administration. They were scrutinized by two experienced electrocardiographers at intervals of 1, 2, 3, 4, 5, 10, 15, and 30 minutes. RESULTS: Data revealed nonsignificant arrhythmias with doses of 2.5, 5.0, and 10.0 mg/kg of intravenous nicotine. The dose of 50 µg/kg induced supraventricular arrhythmias, atrioventricular junctional arrhythmias, and ventricular arrhythmias. Supraventricular bradycardia in 30 (83%; P <.0001), supraventricular arrhythmia in 30 (83%; P <.0001), sinus arrest in 18 (50%; P <.003), atrial ectopics in 24 (67%; P <.0004), and atrial tachycardia in 98 experiments (25%; P <.021). These results were statistically significant. In 18 experiments, sinus arrest was observed to be missing P waves and QRS complexes for a period corresponding to 4:1-10:1 SA block, lasting 2-6 seconds, within 3 seconds of injection. Occurrence of wandering pacemaker was observed in 6 experiments, atrial flutter in 2, and atrial fibrillation in 2, but these incidents were not significant. Atrioventricular junctional arrhythmias consisted of escape beats in 9 subjects (25%; P <.02), premature contractions in 12 (33%; P <.005), first-degree heart block in 9 (25%; P <.02), second degree heart block in 9 (25%; P <.02) and atrioventricular dissociation in 9 (25%; P <.02). All arrhythmias in this category were significant. Ventricular arrhythmias consisted of ventricular premature contractions that were unifocal in 32 subjects (89%; P <.0001), multifocal in 30 (83%; P <.0001), bigeminy in 28 salvos in 18 (50%; P <.003). Sustained ventricular tachycardia (> 30 beats) in 12 experiments (33%; P <.005) proved significant. The dose of 100 µg/kg induced fatal ventricular flutter and ventricular fibrillation. The dog expired and experiments with that dose were not repeated. CONCLUSION: Data reveal dose-dependent arrhythmogenecity of nicotine in dogs. Smaller doses of nicotine did not produce significant arrhythmias. Higher doses, bioequivalent to smoking two standard cigarettes, may generate cardiac arrhythmias of simple to severe nature. Further work in human beings may confirm whether nicotine in cigarette smoke will generate similar cardiac arrhythmias especially in patients with autonomic imbalance and/or compromised and ischemic myocardium.

Randomized comparison of elective stent implantation and coronary balloon angioplasty guided by online quantitative angiography and intracoronary Doppler. DESTINI Study Group (Doppler Endpoint STenting INternational Investigation)

BACKGROUND

The purpose of this study was to compare long-term outcomes of coronary stenting in all lesions (elective stenting) or only in lesions with inadequate morphological and functional results after balloon angioplasty (guided PTCA).

METHODS AND RESULTS

Treatment of multivessel disease, with any lesion length and vessel size, was allowed provided that all lesions were suitable for stent implantation. Patients were randomized to elective stent implantation (n=370) or guided PTCA (n=365). An optimal PTCA result (residual diameter stenosis </=35%, coronary flow reserve measured with a Doppler guidewire >2.0, absence of threatening dissections) was achieved in 166 lesions (43%). The remaining 218 lesions underwent stent implantation (provisional stenting). Final residual diameter stenosis was lower in the elective and provisional stent groups (9.3% and 10.2%) than in the optimal PTCA group (24.8%, P:<0. 00001). On an intention-to-treat analysis, the probability of >/=1 major adverse cardiac event at 12 months was 17.8% in the elective stenting group and 18.9% in the guided PTCA group (20.1% for optimal PTCA and 18.0% for the provisional stenting subgroup, P:=NS). The incidence of repeat target lesion revascularization at 1 year was 14. 9% in the elective stent group and 15.6% in the guided PTCA group (17.6% for optimal PTCA and 14.1% for the provisional stenting subgroup, P:=NS).

CONCLUSIONS

When balloon angioplasty is guided by online quantitative angiography and Doppler-derived coronary flow reserve, with provisional stenting reserved for suboptimal results, early and late clinical outcomes are comparable to those achieved by elective stenting of all patients.

Aneurysm of the membranous ventricular septum

Images

Constrictive pericarditis

The diagnosis of constrictive pericarditis remains a challenge because its physical findings and hemodynamics mimic restrictive cardiomyopathy. Various diagnostic advances over the years enable us to differentiate between these two conditions. This review begins with a case report of constrictive pericarditis, followed by a brief history and discussions of etiologies. Clinical features, radiologic, electrocardiographic, angiographic findings, and hemodynamics of constrictive pericarditis are reviewed. The echocardiographic findings are detailed and the recent advances in Doppler flow velocity patterns of pulmonary, mitral, tricuspid valves and hepatic veins are reported. Nuclear ventriculograms depict rapid ventricular filling in constrictive pericarditis and differentiate it from restrictive cardiomyopathy. Endomyocardial biopsy helps further in recognizing the various types of restrictive cardiomyopathies. Computed tomography and magnetic resonance imaging delineate abnormal pericardial thickness in constrictive pericarditis. Association of characteristic hemodynamic changes and abnormal pericardial thickness > 3 mm usually confirms the diagnosis of constrictive pericarditis. Effusive and occult varieties of constrictive pericarditis are briefly described. This review concludes with emphasizing the importance of pericardial resection.

Hygroscopicity, phase solubility and dissolution of various substituted sulfobutylether beta-cyclodextrins (SBE) and danazol-SBE inclusion complexes

The aim of the present work was to characterize hygroscopicity, phase solubility and dissolution properties for various substituted sulfobutylether beta-cyclodextrins (SBEs) and danazol-SBE inclusion complexes. Moisture sorption was measured using a symmetric gravimetric analyzer. The complexes were characterized by powder X-ray diffraction (XRD) and differential scanning calorimetry (DSC). Moisture sorption isotherms for the SBEs and the complexes showed low moisture sorption at RH <60%. The moisture absorption desorption isotherms for the various SBEs showed very little hysteresis, indicating almost complete desorption. Moisture adsorbed by the various SBE was in the order SBE 7>SBE 4>SBE 5 at 95% RH. Powder XRD data for complexes showed the disappearance of characteristic crystalline peaks for danazol or the formation of amorphous entities and DSC showed the disappearance of the peak of fusion of danazol indicating complex formation. Phase solubility of danazol with various substituted SBEs indicated 1:1 stoichiometry of complexes. The apparent stability constant, as determined by the method of Higuchi and Connors, increased as the degree of substitution of SBEs increased and decreased as the temperature increased. The dissolution of the complexes was significantly greater than that of the corresponding physical mixtures indicating that the formation of amorphous complex increased the solubility of poorly soluble danazol. More than 85% of danazol was released in <10 min, compared to 15% danazol release from the physical mixtures.

Myocardial lesions induced by prolonged alcohol feeding in rhesus monkeys

To elucidate the effects of chronic alcohol ingestion in monkeys a synthetic, adequately balanced, fluid diet providing 40% of total calories from ethanol was gavaged through a stomach tube daily over a period of three months. Clinical, biochemical, radioisotope, and histopathological studies were performed at the beginning and end of the experiment. It was observed that chronic alcohol feeding at this dose level caused maked accumulation of triglycerides, cholesterol, and phospholipids in the serum and the liver. In the heart triglycerides and cholesterol ester were increased. Incorporation studies showed increased synthesis of triglycerides in the heart muscle and liver. Histologically the heart showed fatty change of the myocardium and evidence of focal myocytolysis, atrophy of muscle bundles, and early fibrosis. The liver showed generalized fatty change but no cirrhosis.

Analysis of QT interval in patients with idiopathic mitral valve prolapse

Analysis of QT interval from repeated recordings was made in 56 patients with documented idiopathic mitral valve prolapse (IMVP). The results were compared with a control of 62 healthy volunteers in whom mitral valve prolapse was excluded by both phonocardiography and echocardiography and with two other standard populations, those of Simonson and co-workers and of Ashman. After correction for age, the maximum QT interval of the patients with IMVP exceeded the 97.5 percentile of Simonson population in 51 of 56 patients compared with only three of 62 subjects of the control group. The difference between the QT interval of patients from the upper limits of the predicted mean values of Simonson was significant (P less than 0.002). The mean QTC interval in patients with IMVP was 0.48 +/- 0.035 second compared with 0.038 +/- 0.025 second in the control subjects. The difference between the mean QTC interval in patients with IMVP and the control subjects was significant (P less than 0.005). Spontaneous prolongation in the mean QT interval was noted in 43 of 56 patients with IMVP (76.6 percent) compared with only two of 62 control subjects (3 percent). The incidence of episodic arrhythmias was 72 percent in patients with marked QTC prolongation (mean, 0.58 second) compared with 22.6 percent in patients with lesser degree of QTC prolongation (mean, 0.46 second). The results suggest that QT abnormality is common in patients with IMVP and may play an important role in the genesis of cardiac arrhythmia.

Combined effects of alcohol and nicotine on cardiovascular performance in a canine model

Alcohol and tobacco consumption are correlated. Smokers consume more alcohol than do nonsmokers, and alcohol consumers smoke more than do teetotalers. The independent effects of alcohol and nicotine on the cardiovascular system are well documented, but combined effects of short-term administration are unknown. This experimental work was designed to study the effects due to short-term administration of alcohol and nicotine on cardiovascular system. In phase I, 30 experiments were performed to study the dose-response curve of both the drugs. In phases II and III, 15 dogs were subjected to 30 experiments. In phase II, ethanol, 400 mg/kg, was given i.v., followed by nicotine 50 microg/kg, i.v., and in phase III, sequence of drug administration was reversed to study the effects on hemodynamics and coronary artery blood flow. The dose-response curve established the i.v. dose of ethanol, 400 mg/kg, and nicotine, 50 microg/kg. Ethanol administration caused a nonsignificant increase in heart rate (HR), mean arterial pressure (MAP), left ventricular systolic pressure (LVS), and left ventricular mechanical work (LVMW), and a decrease in maximal rate of increase of LV pressure per second (dP/dt), stroke volume (SV), and systemic vascular resistance (SVR). Left ventricular end-diastolic pressure (LVEDP), pulmonary artery mean pressure (PAM), right atrial pressure (RAP), pulmonary vascular resistance (PVR), myocardial oxygen consumption (MVO2), and average peak velocity of coronary blood flow (APV) had mild significant increases as compared with controls. Nicotine significantly increased heart rate, mean arterial pressures, LVEDP, and pulmonary artery, pulmonary capillary wedge, and right atrial pressures. Nicotine increased dP/dt (2,062-3,188; p < 0.006) and decreased APV (9 to 8; p < 0.03). Combined ethanol followed by nicotine had synergistic increase in HR, SD, MAP, LVS, LVEDP, pulmonary pressures, CO, SV, dP/dt (2,184 > 5,206; p < 0.005), MVO2, and LVMW. However, the excitatory effects of nicotine were attenuated when ethanol was administered after nicotine (dP/dt, reduced from 2,058 to 1,653; p < 0.04, and APV increased from 10 to 12; p < 0.02). We conclude that ethanol increased APV but had nonsignificant effects on the hemodynamics, whereas nicotine reduced the APV and had significant excitatory responses. In combination (i.v.), ethanol + nicotine produced significant synergistic excitatory effects. On the other hand, the nicotine + ethanol combination increased APV and caused attenuation of the excitatory effects of nicotine in dogs.

Incremental value of live/real time three-dimensional transthoracic echocardiography in the assessment of right ventricular masses

This case series demonstrates the incremental value of three-dimensional transthoracic echocardiography (3D TTE) over two-dimensional transthoracic echocardiography (2D TTE) in the assessment of 11 patients with right ventricular (RV) masses or mass-like lesions (three cases of RV thrombus, one myxoma, one fibroma, one lipoma, one chordoma, and one sarcoma and three cases of RV noncompaction, which are considered to be mass-like in nature). 3D TTE was of incremental value in the assessment of these masses in that 3D TTE has the capacity to section the mass and view it from multiple angles, giving the examiner a more comprehensive assessment of the mass. This was particularly helpful in the cases of thrombi, as the presence of echolucencies indicated clot lysis. In addition, certainty in the number of thrombi present was an advantage of 3D TTE. Also, sectioning of cardiac tumors allowed more confidence in narrowing the differential diagnosis of the etiology of the mass. In addition, 3D TTE allowed us to identify precise location of the attachments of the masses as well as to determine whether there were mobile components to the mass. Another noteworthy advantage of 3D TTE was that the volumes of the masses could be calculated. Additionally, the findings by 3D TTE correlated well with pathologic examination of RV tumors, and some of the masses measured larger by 3D TTE than by 2D TTE, which was also validated in one case by surgery. As in the case of RV fibroma, another advantage was that 3D TTE actually identified more masses than 2D TTE. RV noncompaction was also well studied, and the assessment with 3D TTE helped to give a more definitive diagnosis in these patients.

Catheter-induced left internal mammary artery bypass graft dissection

The first reported case of a patient with left internal mammary artery bypass graft dissection secondary to selective coronary and graft arteriography is presented. The intimal tear and false lumen could not be seen with flouroscopy during catheterization. This later led to antero-septal myocardial infarction.

Left atrial abnormality in acute myocardial infarction

This study assessed left atrial abnormality by electrocardiogram as a predictor of left ventricular dysfunction during acute myocardial infarction. Hemodynamic, angiocardiographic, echocardiographic, and serial creatine kinase-MB studies revealed the electrocardiogram to be a significant predictor of location of acute myocardial infarction, prevalence of occlusive disease in coronary vessels, myocardial contractility, low ejection fraction, increased left ventricular end-diastolic pressure, and serial creatine kinase-MB.

Usefulness of left atrial abnormality for predicting left ventricular hypertrophy in the presence of left bundle branch block

The objective of this study was to identify left atrial (LA) abnormality on the electrocardiogram and other related variables as predictors of left ventricular (LV) hypertrophy in the presence of left bundle branch block (LBBB). In the presence of complete LBBB, the diagnosis of electrocardiographic abnormalities is problematic and that of LV hypertrophy remains difficult. The usual electrocardiographic criteria applied for the diagnosis of LV hypertrophy may not be reliable in the presence of LBBB. Therefore, noninvasive criteria will help physicians diagnose LV hypertrophy with electrocardiography. LA abnormality on the electrocardiogram was assessed by 2 independent observers as predictor of LV hypertrophy in the presence of LBBB in 120 patients, and data were compared with those of 100 patients without LA abnormality. LV mass was calculated from echocardiographic data. Besides LA abnormality, the other variables studied for prediction of LV hypertrophy were gender, age, body surface area, body mass index, frontal axis, and QrS duration. Of the 6 criteria analyzed, the P terminal force was found to be the most common and consistent criterion to detect LA abnormality. LV hypertrophy was confirmed by echocardiographic determination of LV mass in both groups. Observers reliably differentiated between the hypertrophied and normal-sized left ventricle in the presence of LBBB by correlating LA abnormality with LV mass determined by echocardiography. Observer 1 detected LA abnormality in 89% and observer 2 in 84% of patients. False-positive results were present in 11% and 16%. The observer's recognition of LA abnormality in the present study was 91%. The 2 observers showed a sensitivity of 81% and 79% and a specificity of 91% and 88%, respectively, when diagnosis of LV hypertrophy was determined. LV mass increased significantly and was diagnostic of LV hypertrophy in 92% of patients with LA abnormality. In the remaining 11 patients (8%), the LA abnormality was of marginal abnormal magnitude. Each 0.01-mV/s increase in LA abnormality gave an increase of 30 g of LV mass. LV mass was increased in 86% of patients when corrected by body surface area. LV hypertrophy in the presence of LBBB on electrocardiography was found in only 13 patients (10%) when the 6 frequently used conventional criteria for diagnosis of LV hypertrophy by electrocardiography were used. Regression analysis revealed LA abnormality to be a strong independent predictor of increased LV mass. Multivariate analysis also revealed age, body mass index, body surface area, frontal axis, and QrS duration to be significant predictors of LV mass. This noninvasive study correlates LA abnormality by electrocardiogram and LV hypertrophy with echocardiography to conclude that LA abnormality was significantly diagnostic of LV hypertrophy in the presence of LBBB. Age, body mass index, body surface area, frontal axis, and QrS duration were also significant predictors of LV mass.

Left ventricular function after cigarette smoking by chronic smokers: comparison of normal subjects and patients with coronary artery disease

Twenty normal subjects and 25 patients with coronary artery disease underwent systolic time interval analysis before and after rapidly smoking two cigarettes. A slight increase in heart rate and arterial pressure was seen in both groups. In patients with coronary artery disease, preejection period/left ventricular ejection time ratio increased; in normal subjects it decreased. Left ventricular performance is diminished after cigarette smoking among subjects who have preexisting significant coronary artery disease.

Diagnostic utility of memory equipped transtelephonic monitors

The diagnostic utility of memory-equipped transtelephonic electrocardiographic monitors was evaluated in a series of 31 patients referred for evaluation of unexplained syncope (16), presyncope (8), or palpitations (7). Previous nondiagnostic workups included 4 +/- 1 days (mean +/- standard error of the mean) of 24-hour Holter and/or in-hospital telemetric monitoring per patient. The duration of monitoring averaged 31 +/- 2 days per patient. Electrocardiographic recordings were made during a typical symptom episode in 9 of 31 (29%) patients, including 0 of 16 with syncope, 3 of 8 (37%) with presyncope, and 6 of 7 (86%) with palpitations (p less than .001). The probability of recording typical symptoms was strongly influenced by their previous frequency. Potentially causal arrhythmias were documented in 5 of 7 (71%) patients with palpitations, but in none of the other symptom subgroups (p less than .001). Monitoring led to changes in therapy in only two patients. During followup of 9 +/- 1 months, symptoms continued in 4 of 16 (25%) with syncope, 7 of 8 (87%) with presyncope, and 7 of 7 (100%) with palpitations (p = .001). The diagnostic utility of these devices thus appears to be low in patients with previously unexplained syncope or presyncope. The yield was high in those monitored for palpitations, which may be in part attributable to the greater frequency of symptoms observed in this group.

The prediction of cardiac risk in patients undergoing vascular surgery

In an attempt to determine whether noninvasive cardiac testing could be used to assess cardiac risk in patients undergoing surgery for vascular disease, the authors studied 96 patients. Seventy-seven patients eventually underwent major vascular surgery with 11 (14%) experiencing a significant cardiac complication. Thallium imaging was much more likely to be positive (p less than 0.01) in patients with a cardiac complication; however, there was a significant number of patients with cardiac complications who had a positive history or electrocardiogram for myocardial infarction. When grouped by complication and history of infarction, thallium imaging, if negative, correctly predicted low cardiac risk in the group with a history of infarction. Thallium imaging, however, did not provide a clear separation of risk in those without a history of infarction. Age and coronary angiography, on the other hand, did reveal significant differences within the group without a history of infarction. The resting radionuclide ejection fraction followed a similar pattern to thallium imaging. It is concluded that a positive history of myocardial infarction at any time in the past is the strongest risk predictor in this population and that the predictive value of noninvasive testing is dependent on this factor. Considering these findings, a proposed scheme for assessing risk that will require further validation is presented.