Arrhythmic emergencies in ICCU.

Atrial fibrillation and sustained ventricular arrhythmias are the most common arrhythmias accompanying acute coronary syndromes. Arrhythmias are associated with worse clinical course and increased risk of in-hospital, short-term and long-term mortality in patients with ST-elevation myocardial infarction. This review summarizes the current knowledge on most prevalent arrhythmias in patients with ACS and their management in intensive coronary care unit.

Relationship between hypoplastic right coronary artery and coronary artery anomalies.

OBJECTIVES: The frequency of hypoplastic right coronary artery (HRCA) and its contribution to coronary artery anomalies (CAAs) has not been thoroughly studied. Here we aimed to investigate whether a casual relationship exists between the presence of HRCA and CAAs. MATERIALS AND METHODS: We retrospectively reviewed coronary angiography records of 7500 patients. The images were carefully assessed for coronary artery (CA) anatomy and CAAs. Overall, we compared CAAs at the presence and absence of HRCA and evaluated potential association between HRCA and CAAs. Besides, we grouped HRCA patients according to the presence of CA disease (CAD) into two groups and compared their CAAs. RESULTS: While the percentage of HRCA was 6.2%, it was 3.34% for CAAs. The percentage of CA with anomalous origin (CAAO) at the presence of HRCA was significantly higher than the presence of normal right coronary artery (NRCA) (p < 0.01). Similarly, the percentage of absent left main coronary artery (ALMCA) was also considerable increased in HRCA patients with respect to the patients with NRCA (p < 0.01). The percentage of CAAO was notably higher in the CAD (-) than CAD (+) patients with HRCA (p < 0.01). Likewise, the prevalence of ALMCA was also noticeably higher in the CAD (-) than CAD (+) patients with HRCA (p < 0.01). CONCLUSIONS: HRCA is a clinically significant and frequently encountered congenital variation. The present observations indicate that the presence of HRCA is closely associated with a high prevalence of CAAO, particularly with increased rate of ALMCA.

Electrical cardioversion of atrial fibrillation in a case of dextrocardia.

Although atrial fibrillation is one of the most frequent and widespread cardiac arrhythmias, there is not sufficient data on frequency and electrical cardioversion of this arrhythmia in cases of dextrocardia. The present case report describes a 66-year-old woman with atrial fibrillation and dextrocardia who was admitted to hospital with a complaint of palpitations; no cause of the atrial fibrillation was found. Electrical cardioversion was performed for termination of the arrhythmia. By placing the anterior paddle in the right parasternal area and the lateral paddle in the area where the apex of the left ventricle palpated at the right side of the chest, cardioversion was performed and sinus rhythm was achieved.

Detection of myocardial injury after internal cardioversion for atrial fibrillation.

BACKGROUND: Cardiac troponin levels do not rise to marked levels after external cardioversion of atrial fibrillation. Subsequent test discharges during implantation of cardioverter defibrillators may cause an elevation of cardiac troponin levels, but are still controversial. OBJECTIVE: To determine whether the biomarkers of cardiac injury increase after internal cardioversion (IC) of atrial fibrillation. METHODS: Forty-four patients with chronic atrial fibrillation were studied (mean age 59 +/-7 years). Electrode catheters were inserted through the femoral vein. One of these was positioned in the lower right atrium. A second defibrillation electrode was placed in the coronary sinus and an additional catheter was positioned in the right ventricular apex in order to obtain satisfactory R wave synchronization and to provide postshock ventricular pacing. The shocks were delivered by external defibrillator. Starting with a test shock of 1 J intensity, the energy was increased in steps (to maximum 15 J) until cardioversion was achieved. At least 1 min was permitted to elapse between unsuccessful defibrillation attempts before the next shock was applied. Blood samples for serum levels of cardiac troponin T, cardiac troponin I, creatine kinase MB and myoglobin were drawn before and 2 h, 4 h, 8 h and 24 h after IC. Each level of biomarker was compared with baseline. RESULTS: In 40 of 44 patients, IC was successful at a mean cardioversion threshold of 7.6+/-3.3 J. Although the serum levels of these biomarkers tended to rise, marked elevation was not detected in any of samples (P>0.05 for each). There was no correlation between the levels of biomarkers and the number and energy of shocks applied. No severe complications were observed. CONCLUSIONS: Following uncomplicated IC of atrial fibrillation, cardiac biomarkers do not rise to marked levels, which indicates that significant myocardial injury does not occur by shocks in the usual dosage.

Clinical importance of the initiation pattern of monomorphic ventricular tachycardia.

We investigated the clinical and electrophysiological features of monomorphic ventricular tachycardia (MVT) with different initiation patterns in patients with implantable cardioverter defibrillator to assess whether there is a relationship between the initiation patterns of sustained MVT and clinical characteristics, and the efficacy of antiarrhythmic and electrical therapy. Fifty-five stored IECGs in twenty-two patients with MVT were evaluated. All MVT episodes were classified as initiating with ventricular premature beats (non-sudden onset MVT) or without ventricular ectopy preceding tachycardia (sudden onset MVT). Non-sudden onset MVT was characterized by shorter tachycardia cycle length (CL) and required higher shock energy for termination. Sudden onset MVT was precipitated by shortening of the sinus CL before tachycardia and was more common with relatively better preserved systolic function.

Long-short sequence may predict immediate recurrence of atrial fibrillation after external cardioversion.

AIM: We thought, that analysis of surface electrocardiograms recorded immediately after electrical external cardioversion (EC) might enlighten the mechanisms responsible for immediate recurrence of atrial fibrillation (AF) and especially to test whether atrial ectopic beats (PAC) with long-short (LS) sequence are related to the recurrence of arrhythmia after cardioversion in patients with chronic AF. METHODS AND RESULTS: One hundred and thirty-seven patients (mean age 57+/-7 years) undergoing EC for chronic AF entered the study. Evaluation of the patients included clinical history, physical examination, ECG, routine laboratory tests, and transthoracic echocardiography. The cardioversion was performed with monophasic waveform shock and immediately after successful EC, 1 min of recording of the ECG lead II was analysed. One hundred and twenty patients (87%) of 137 patients enrolled in the study had had successful EC and 33 (27%) of them experienced immediate recurrence of AF within 1 min (Group I) and 87 patients had no arrhythmia recurrence (Group II). In group I in 24 patients (73%) recurrence of AF was initiated by PAC with LS sequence. In only 12 of 87 (13%) patients who did not experience immediate recurrence of AF (Group II) PACs were recorded. CONCLUSIONS: Atrial ectopic beats (PACs) with LS sequence, being responsible for AF relapse in about 70% of patients, might predict early re-initiation of arrhythmia after EC. Electrocardiograms, recorded immediately after EC, are a potentially feasible approach in establishing the patterns of AF relapse that may be useful in the management of AF recurrence.

Implantable event loop recorder prevents misdiagnosis of underlying arrhythmia in patients with unexplained palpitations--a case report.

The implantable event loop recorder is informative in the establishment of underlying arrhythmia and may aid in treatment of patients with infrequent unexplained palpitations.

Comparison of QT dispersion between primary coronary angioplasty and thrombolytic therapy for acute myocardial infarction.

BACKGROUND: Previous studies have documented that reduction in QT dispersion after thrombolytic treatment in acute myocardial infarction depends on reperfusion status as well as infarct site. Primary percutaneous transluminal coronary angioplasty as compared with thrombolytic therapy has been shown to result in higher patency rates of the infarct vessel. OBJECTIVES: To evaluate whether primary PTCA has a more favorable effect on reducing QT dispersion in patients with acute MI as compared to thrombolytic treatment. METHODS: The study population included 42 consecutive patients (33 men, mean age 58 +/- 11 years) with acute MI (24 anterior wall, 18 inferior wall) who were treated with primary PTCA (group A, n = 21) or thrombolytic therapy (group B, n = 21) at 3.9 +/- 2 hours after symptom onset. QT intervals were measured before and 24 hours after treatment. RESULTS: On the admission electrocardiogram, patients with anterior MI had higher values of QT and QTc dispersions than patients with inferior MI (52 +/- 9 vs. 36 +/- 9 msec, P < 0.05 and 61 +/- 4 vs. 56 +/- 4 msec, P = 0.002, respectively). There was a significant reduction in QT and QTc dispersions from admission to 24 hours in all patients (from 50 +/- 9 to 37 +/- 9 msec, P < 0.001 and from 59 +/- 5 to 42 +/- 5 msec, P < 0.001, respectively), and also in group A (from 49 +/- 8 to 32 +/- 5 msec, P < 0.001 and from 58 +/- 5 to 38 +/- 3 msec, P < 0.001, respectively) and in group B patients (from 51 +/- 10 to 42 +/- 10 msec, P < 0.01 and from 60 +/- 4 to 46 +/- 5 msec, P < 0.001, respectively). QT and QTc dispersions were found to be shorter in group A at 24 hours after treatment than in group B (32 +/- 5 vs. 42 +/- 10 msec, P < 0.001 and 38 +/- 3 vs. 46 +/- 5 msec, P < 0.001, respectively). CONCLUSIONS: Reperfusion therapy with primary PTCA or thrombolytic agents reduces QT and QTc dispersions in acute MI. QT and QTc dispersions after reperfusion treatment are shorter with primary PTCA than with thrombolytic therapy.

Evaluation of C-reactive protein, fibrinogen and antithrombin-III as risk factors for coronary artery disease.

BACKGROUND: Inflammation is an important feature of atherosclerotic lesions and increased production of the acute-phase reactant. The contribution of coagulation factor to the development of coronary artery disease has not yet been clearly established. OBJECTIVES: To test whether C-reactive protein, fibrinogen and antithrombin-III are associated with angiographic CAD, history of myocardial infarction and extensive atherosclerotic involvement. METHODS: Blood samples were tested for CRP, fibrinogen and AT-III levels from 219 individuals undergoing coronary angiography. RESULTS: CRP was higher in patients with CAD (0.95 +/- 1.31, n = 180, vs. 0.39 +/- 0.61 mg/dl, n = 39, P < 0.0001) and in those with a history of MI (1.07 +/- 1.64, n = 96, vs. 0.65 +/- 0.72 mg/dl, n = 84, P < 0.05) than in control subjects. The patients who developed unstable angina had higher CRP levels than the patients with stable CAD (2.07 +/- 2.38, n = 7, vs. 0.80 +/- 1.13 mg/dl, n = 173, P < 0.001). Fibrinogen was significantly higher in patients with CAD than in those without CAD (298 +/- 108 vs. 258 +/- 63 mg/dl, P < 0.01). In patients with CAD, mean AT-III value was less than in patients without CAD, but this difference was not statistically significant (P = 0.08). No difference was found in CRP, fibrinogen and AT-III values among the patients with single, double or triple vessel disease. CONCLUSIONS: CRP is elevated in patients with CAD and a history of MI. Elevated levels of CRP at the time of hospital admission is a predictive value for future ischemic events. There is an association between higher levels of fibrinogen and CAD. The association of AT-III levels with CAD needs testing in further studies.

Observations on the onset of torsade de pointes arrhythmias in the acquired long QT syndrome.

OBJECTIVE: Premature ectopic beats may create a specific sequence of events (e.g. short-long-short) preceding Torsade de Pointes arrhythmias (TdP) in the long QT syndrome. The relevance of this sequence for the initiation of TdP is not clear. In our dog model of TdP, interventricular dispersion (DeltaAPD=left-right ventricular monophasic action potential duration: APD) is associated with TdP, therefore we tested the hypothesis that the ectopic beats contributes to DeltaAPD. METHODS: In 17 anaesthetized dogs with chronic AV-block, which showed spontaneous TdP after class III medication, APD was analyzed to 1. quantitate the alterations due to (multiple) ectopic beats on the left and right APD (measured with endocardial catheters) and 2. compare the DeltaAPD prior to the occurrence of premature beats (steady state) in dogs with non-sudden onset of TdP (n=10) and sudden onset TdP (n=7). Three phases were distinguished: phase 1: steady state beats prior to ectopic beats, phase II: the beat(s) belonging to the dynamic phase, and phase III: the beat causing TdP. Because the coupling interval of premature beats in this condition often falls within the APD, the DeltaAPD(50) was validated as an alternative for the previously applied DeltaAPD(100) (r=0.51, P<0.01). RESULTS: In steady state (phase I) DeltaAPD(50) is longer in the sudden onset TdP (130+/-35 ms) as in the non-sudden onset TdP (65+/-40 ms). In the non-sudden TdP group the dynamic phase II contribute to the heterogeneity in APD, i.e. LV-APD increases more than RV-APD leading to a DeltaAPD(50) increase to 130+/-100 ms (P<0.01) just preceding TdP (phase III). CONCLUSION: The synergism between ectopic beats (short-long-short sequence) and DeltaAPD create the circumstances for TdP initiation.