Giuseppe Critelli

Transesophageal pacing for prognostic evaluation of preexcitation syndrome and assessment of protective therapy

An esophageal lead was used to perform decremental atrial pacing and elective induction of atrial fibrillation (AF) in 5 patients with the Wolff-Parkinson-White (W-P-W) syndrome before and after amiodarone therapy. In the control state, 1:1 atrioventricular (AV) conduction over the accessory pathway ranged from 220 to 260 ms (mean 232). The shortest R-R interval during AF ranged from 190 to 210 ms (mean 198). The ventricular rate ranged from 175 to 212 beats/min (mean 196). After amiodarone therapy, the shortest cycle length with 1:1 AV conduction increased in all patients, ranging from 290 to 540 ms (mean 370); during AF, no preexcited beat was present in 2 patients, whereas the minimal preexcited R-R interval in the remaining 3 was 290, 240, and 370 ms, respectively. The ventricular response during AF decreased in all patients. Thus, esophageal pacing is a useful method for identifying patients at risk with the W-P-W syndrome and for assessing appropriate management in individual patients. Amiodarone provides protection against life-threatening arrhythmias in these patients.

Angina in Fabry Disease Reflects Coronary Small Vessel Disease

Background—Chest pain is frequently reported in Fabry disease (FD). However, its mechanism and clinical relevance are unclear. Methods and Results—Basal troponin I level, exercise stress test, single-photon emission computed tomography imaging with 99mTc sestamibi, coronary angiography with thrombolysis in myocardial infarction (TIMI) frame count and left ventricular angiography and endomyocardial biopsy were obtained in 13 patients with FD with angina. Ratio of external to lumen diameter of intramural arteries (E/L ratio), myocyte diameter, and extent of fibrosis were morphometrically evaluated by using tissue sections. Controls for coronary angiography and histology were 25 patients with FD without angina and 20 mitral stenosis patients with normal left ventricular function. Troponin I level was elevated in 6 of the 13 patients. Exercise stress test showed evidence of myocardial ischemia, and single-photon emission computed tomography was positive for stress-induced perfusion defects in all patients with FD with angina. Epicardial coronaries were structurally normal but showed slow flow in all and were associated with aneurisms of posterior left ventricular wall in 3 cases. Histology showed remarkable lumen narrowing of most intramural arteries (mean E/L ratio=3.5±1.2; P<0.001 versus both control groups), because of hypertrophy and proliferation of smooth muscle and endothelial cells, both engulfed by glycosphingolipids. Replacement fibrosis exceeded that of both controls (P<0.001). Small vessel disease correlated with coronary slow flow and extent of fibrosis, but did not with patients’ age, sex, and degree of left ventricular hypertrophy. Conclusions—patients with FD with angina have perfusion defects, slow coronary flow, and luminal narrowing of intramural arteries. Small vessel disease may contribute to symptomatic limitation and progressive myocardial dysfunction.

Resting and ambulatory ECG predictors of mode of death in dilated cardiomyopathy

With the purpose of verifying whether the electrocardiogram (ECG) pattern alone can predict the mode of death in dilated cardiomyopathy, data from 12-lead ECGs and 48-hour arrhythmia monitoring were evaluated in 67 patients with dilated cardiomyopathy. During a mean follow-up period of 3 +/- 2 years, death from congestive heart failure occurred in 18 patients (27%), whereas 10 (15%) died suddenly (NS). Multivariate analysis showed that left bundle branch block (p < 0.001) and left atrial enlargement (p < 0.001) were independently related to death from congestive heart failure. Ventricular arrhythmias of Lown grade 4A or 4B (p < 0.001) and repolarization time, as assessed by QTc-QRS interval (p < 0.05), were independent predictors of sudden death. It is concluded that ECG features alone may be helpful for risk factor characterization of dilated cardiomyopathy patients, provided that multiple ECG criteria are utilized at time of diagnosis.

Electrocardiographic pattern of Brugada syndrome disclosed by a febrile illness: clinical and therapeutic implications

BACKGROUND Recent studies have identified a direct link between the ionic mechanisms responsible for the electrocardiographic (ECG) pattern of the Brugada syndrome (BS) and the in vitro experimental temperature, pointing to the possibility that some BS patients may display the ECG phenotype only during a febrile state, being in this setting at risk of lethal arrhythmias. CASE REPORT A 53-year-old man referred to the emergency room for abdominal pain and fever. The ECG showed dome-shaped ST-segment elevation in V1-V3, as in the typical BS. The personal and family history were unremarkable for syncope and sudden death and physical, laboratory and ultrasound examinations were negative. On day 3, at normal body temperature, the patients ECG returned to normal and the ECG abnormalities were later reproduced with intravenous flecainide. The patient refused the implantation of a loop recorder and was discharged after 6 days. He has remained asymptomatic during 2 years of follow-up. CONCLUSIONS The typical ECG phenotype of BS disclosed by a febrile illness confirms the in vitro experimental data that previously established a correlation between ECG pattern of BS and temperature variations. The clinical and therapeutic implications of these findings are discussed.

Evaluation of noninvasive tests for identifying patients with preexcitation syndrome at risk of rapid ventricular response

Intermittent preexcitation, block in the accessory pathway after intravenous injection of ajmaline or procainamide, and block in the accessory pathway during exercise usually exclude a short antegrade refractory period of an accessory pathway in patients with the Wolff-Parkinson-White syndrome. This report describes three patients with these findings suggestive of a relatively long antegrade effective refractory period of the accessory pathway in whom life-threatening ventricular response occurred during atrial fibrillation. In the first patient with a pattern of intermittent preexcitation, rapid ventricular response with wide QRS was present during atrial fibrillation. In the second patient in whom preexcitation disappeared after intravenous injection of ajmaline or procainamide as well as during exercise testing, atrial pacing showed 1:1 conduction over the accessory pathway at a cycle length of 220 msec and the shortest R-R interval during induced atrial fibrillation was 190 msec. The third patient, with no evidence of preexcitation during sinus rhythm, presented antidromic reciprocating tachycardia and atrial fibrillation with life-threatening ventricular response, the minimal R-R interval being 220 msec. Noninvasive tests in the preexcitation syndrome lack sufficient prognostic sensitivity. The evaluation of ventricular response during induced atrial fibrillation represents the most reliable means of identifying such patients at risk.

Automatic “Scanning” by Radio-frequency in the Long-Term Electrical Treatment of Arrhythmias

The use of programmed electrical stimulation in the long‐term treatment of re‐entry tachycardia offers encouraging perspectives. Among the others proposed, the “scanning” system seems to be the most effective. However, an implantable stimulator with these features is not yet available and, thus, a temporary external lead is required. These difficulties have been overcome by utilizing radiofrequency to synchronize and stimulate. An implantable device was therefore designed which is triggered by the patient and automatically searches the interruption zone of the tachycardia by exploring the R‐R cycle. The external transmitter, which can produce one or two synchronized impulses, is programmed to scan the R‐R cycle with progressive steps of 5 or 10 ms; when tachycardia is interrupted, further stimulation is inhibited. The implanted module connected to an endocavitary lead does not have any power supply and, therefore, is very small. The efficacy of this method has been demonstrated in 4 patients with supraventric‐ular lacycardia (3 with WPW syndrome) resistant to conventional pharmacologic therapy. (PACE, Vol. 2, May‐June 1979)

Recovery of contractility of viable myocardium during inotropic stimulation is not dependent on an increase of myocardial blood flow in the absence of collateral filling

OBJECTIVES The purpose of this study was to determine whether contractile recovery induced by dobutamine in dysfunctioning viable myocardium supplied by nearly occluded vessels is related to an increase in blood flow in the absence of collaterals. BACKGROUND Dobutamine is used to improve contractility in ventricular dysfunction during acute myocardial infarction. However, it is unclear whether a significant increase in regional blood flow may be involved in dobutamine effect. METHODS Twenty patients with 5- to 10-day old anterior infarction and > or =90% left anterior descending coronary artery stenosis underwent 99mTc-Sestamibi tomography (to assess myocardial perfusion) at rest and during low dose (5 to 10 microg/kg/min) dobutamine echocardiography. Rest echocardiography and scintigraphy were repeated >1 month after revascularization. Nine patients had collaterals to the infarcted territory (group A), and 11 did not (group B). RESULTS Baseline wall motion score was similar in both groups (score 15.9+/-1.3 vs. 17.4+/-2.0, p = NS), whereas significant changes at dobutamine and postrevascularization studies were detected (F[2,30] = 409.79, p < 0.0001). Wall motion score improved significantly (p < 0.001) in group A both at dobutamine (-5.3+/-2.2) and at postrevascularization study (-5.5+/-1.9), as well as in group B (-3.9+/-2.8 and -4.5+/-2.4, respectively). Baseline 99mTc-Sestamibi uptake was similar in both groups (62.9+/-9.7% vs. 60.3+/-10.4%, p = NS), whereas at dobutamine and postrevascularization studies a significant change (F[2,30] = 65.17, p < 0.0001) and interaction between the two groups (F[2,30] = 33.14, p < 0.0001) were present. Tracer uptake increased significantly in group A both at dobutamine (+ 10.9+/-7.9%, p < 0.001) and at postrevascularization study (12.1+/-8.7%, p < 0.001). Conversely, group B patients showed no change in tracer uptake after dobutamine test (-0.4+/-5.8, p = NS), but only after revascularization (+8.8+/-7.2%, p < 0.001). CONCLUSIONS The increase in contractility induced by low dose dobutamine infusion in dysfunctional viable myocardium supplied by nearly occluded vessels occurs even in the absence of a significant increase in blood flow.

Electrocardiographic correlates with left ventricular morphology in idiopathic dilated cardiomyopathy

The purpose of the present study was to verify whether the electrocardiographic pattern of patients with idiopathic dilated cardiomyopathy (IDC) might be useful in predicting measurements of left ventricular (LV) morphology. A total of 12 electrocardiographic criteria for LV enlargement were evaluated in 67 patients with IDC, aged 14 to 68 years (mean 48), and were correlated to LV wall thickness, volume and mass, as assessed at angiography (all patients) and echocardiography (50 patients). Linear regression analysis showed weak correlations between multiple electrocardiographic criteria and LV wall thickness, volume and mass. Multiple logistic regression analysis showed that total 12-lead QRS amplitude, voltage criteria of Sokolow and Lyon, overshoot and U-wave inversion were the variables significantly related to LV wall thickness, as assessed by angiography (r = 0.55, p less than 0.005) and echocardiography (r = 0.43, p less than 0.025). The sum of T/R-wave ratios, the RV6/RV5 ratio and the Romhilt-Estes score were predictors of LV end-diastolic volume, as determined by angiography (r = 0.83, p less than 0.001) and echocardiography (r = 0.77, p less than 0.005). Total 12-lead QRS amplitude and the sum of T/R-wave ratios were the only independent predictors of LV mass, either angiographically (r = 0.81, p less than 0.001) or echocardiographically measured (r = 0.71, p less than 0.025). It is concluded that a single electrocardiographic criterion for prediction of LV morphology in patients with IDC is barely effective. Multiple electrocardiographic criteria should be utilized to better predict LV mass and distinguish reliably between LV wall thickening and dilatation.

The Permanent Form of Junctional Reciprocating Tachycardia

In 1967, Coumel et al. [1] described a fascinating tachycardia with a normal QRS occurring predominantly in infants and children. Due to the incessant nature of this tachycardia the arrhythmia was named “permanent junctional reciprocating tachycardia” (PJRT). Although the clinical characteristics and electrocardiographic findings of PJRT have been confirmed following the original reports of the French authors, controversy has persisted for many years concerning the pathophysiologic substrate of this arrhythmia [2–9]. Recent data strongly suggest that PJRT represents a “variant” form of the preexcitation syndromes [10–17].

Slow coronary flow and stress myocardial perfusion imaging. Different patterns in acute patients.

Objective We investigated myocardial perfusion in acute patients with slow coronary flow (SCF) at angiography. Whether impaired myocardial perfusion occurs in acute patients with SCF is unknown. Methods We enrolled 28 consecutive patients with SCF in the epicardial coronary arteries with no evidence of significant stenosis. SCF affected a single coronary artery in 14 patients (group A) and all three coronary vessels in 14 others (group B). Coronary angiography was repeated after dipyridamole infusion and single photon emission computed tomography was performed using dipyridamole as the stress agent. The Thrombolysis in Myocardial Infarction frame count was measured in SCF vessels at baseline and after dipyridamole infusion. Results Mean Thrombolysis in Myocardial Infarction frame count significantly decreased after dipyridamole in both groups. At baseline, mean values of the single photon emission computed tomography score were 31.5 ± 1.6 and 25.1 ± 2.1 in groups A and B, respectively. After dipyridamole, they increased from 31.5 ± 1.6 to 37.8 ± 1.4 (P < 0.001) in group A, whereas a further decrease to 15.0 ± 1.2 (P < 0.005) was observed in group B. Conclusions An opposite behavior of myocardial perfusion was observed after dipyridamole infusion: a normal response in patients with SCF affecting one single coronary artery versus an ischemic-like response in those with CSF affecting all three coronary arteries.