Evaluation by Cardiopulmonary Exercise Test of DDDR Versus DDD Pacing

In eight patients (age 62 ± 6 years) a DDDR pacemaker was implanted for sick sinus syndrome (three cases) or second- and third-degree AV block (five cases). In five subjects chronotropic incompetence (maximal heart rate on effort < 110 beats/min) was present before implantation. One month after implantation the patients were randomized to DDDR or DDD pacing for 3 weeks each, with subsequent crossover, and at the end of each period a symptom limited Cardiopulmonary exercise test (25 watts/2 min) was performed and the patients were requested to fill a symptoms questionnaire. Results: DDDR pacing, compared to DDD, was associated with higher maximal heart rates (127 ± 20 vs 110 ± 27 beats/min, P < 0.02), higher (VO₂ max (25.4 ± 6.1 vs 21.5 ± 7.8 mL/kg/per min, P < 0.03) and higher VO₂ at the anaerobic threshold (20.3 ± 5.0 vs 15.8 ± 4.9 mL/kg per min, P < 0.03), without significant differences in mean exercise time (526 ± 193 vs 472 ± 216 sec, NS). The increase in VO₂ max obtained in DDDR versus DDD was significantly related to the increase in maximal heart rate (r = 0.72, P < 0.05) and the increase in VO₂ at the anaerobic threshold obtained in DDDR versus DDD was related to the increase in heart rate at the anaerobic threshold (r = 0.81, P < 0.02). In patients with chronotropic incompetence the improvement obtained in DDDR versus DDD was even more significant (VO₂ max = 22.7 ± 5.9 vs 16.1 ± 4.4 mL/kg per min, P < 0.03; VO₂ at the anaerobic threshold = 18.4 ± 5.1 vs 13.2 ± 2.8 mL/kg per min, P < 0.05; exercise time = 438 ± 132 vs 352 ± 150 sec, P < 0.02). In the population as a whole, no significant differences were found relative to subjective symptoms, meanwhile in patients with chronotropic incompetence a better subjective tolerance was apparent with DDDR than with DDD pacing. In conclusion, DDDR pacing induces a significant improvement of exercice capacity, in comparison to DDD pacing, related to the ability to reach higher heart rates during exercise. This phenomenon is particulary evident in patients with chronotropic incompetence in whom DDDR pacing also is subjectively better tolerated.     

Overdrive and Programmed Atrial Electrostimulation in the Study of the Electrogenetic Mechanism of Atrial Flutter in Man

The response of atrial flutter (AF) to programmed atrial stimulation (PAS) (13 cases) and overdrive atrial pacing (OAP) ws studied in a total of 18 patients. During PAS the return cycle was equal to the basic cycle of AF in six patients, shorter in one patient, and slightly longer in six; it was never compensatory. ATrial flutter terminated in two patients by PAS and by OAP in three. In 4 patients, PAS resulted in an acceleration of the AF rate, followed by spontaneous interruption within 2 seconds. In the remaining patients, the stimulation either converted the AF into an uncommon type of AF (two patients) or into atrial fibrillation that was followed by spontaneous return to sinus rhythm. In two patients it was possible to reproduce the AF with PAS; in one of the patients another type of AF was induced. Some of the data observed suggest a re-entry circuit as the electrogenetic mechanism responsible for AF in man.     

The release of β- thromboglobulin and platelet factor 4 during extracorporeal circulation for open heart surgery

Cardiopulmonary bypass is extremely damaging to platelets and it causes a quantitative and qualitative alteration in their functions. We evaluated the release of two platelet-specific proteins, beta-thromboglobulin (beta TG) and platelet factor 4 (PF4), in patients who underwent extracorporeal circulation for open heart surgery. A parallel release (basal value beta TG: 119.6 ng/ml, PF4 30 ng/ml) was present for both proteins in a time dependent fashion until the end of extracorporeal circulation. High average levels were observed in patients in whom the bypass was stopped after about 1 h (beta TG 1606 ng/ml, PF4 745 ng/ml) and similarly in those in whom the bypass was stopped after about 2 h (beta TG 1540 ng/ml, PF 4754 ng/ml). No correlation was found either between the level of PF4 and the additional heparin administered after the initial standard dose (r = 0.29, P greater than 0.10) and between the level of PF4 and the amount of heparin consumed during the bypass (r = 0.05, P greater than 0.5).     

Effects of Cardiac Resynchronization Therapy on Diastolic Function: Evaluation by Radionuclide Angiography

While the beneficial effects of cardiac resynchronization therapy (CRT) on left ventricular (LV) systolic function have been demonstrated, no information is available regarding its effects on LV diastolic function during exercise. Using radionuclide angiography, we prospectively evaluated the effects of CRT on diastolic function at rest and during exercise in 15 patients consecutively referred for CRT. All patients underwent equilibrium Tc⁹⁹ radionuclide angiography with bicycle exercise performed (1) at baseline; (2) immediately after CRT implantation, in spontaneous rhythm and during CRT; and (3) after 3 months of biventricular stimulation. Diastolic function was assessed by measurements of peak filling rate (PFR). At baseline, activation of biventricular stimulation influenced PFR neither at rest (1.06 ± 0.34 vs 1.07 ± 0.50 mL/s during spontaneous rhythm, P = 0.9) nor during exercise (1.45 ± 0.62 vs 1.33 ± 0.48 mL/s, P = 0.3). At 3 months, improvements were observed in New York Heart Association functional class and systolic function. By contrast, no improvement in diastolic function was observed either at rest (PFR = 1.11 ± 0.45 vs 1.07 ± 0.50 mL/s in spontaneous rhythm at baseline, P = 0.6) or during exercise (1.23 ± 0.50 vs 1.33 ± 0.48 mL/s, P = 0.2). These observations indicate that the intermediate benefits conferred by CRT on LV systolic function at rest and during exercise were not accompanied by similar improvements in diastolic function .     

A Multicenter Evaluation of a Single-Pass Lead VDD Pacing System

Since June 1985 until April 1989, 237 patients (130 males, 107 females, aged 22 to 95 years, mean 71) with symptomatic AV conduction disturbances and competent sinus node, were implanted with a single-pass lead VDD pacing system in 30 centers and followed-up for at least 6 months. The ventricular pacing lead incorporated two atrial ring 3-cm apart electrodes, positioned within the right atrial cavity without contact with the heart wall, in order to detect the atrial activity, which is differentially processed by the pacemaker. At implant, mean atrial electrogram amplitude, derived from a custom pacemaker system analyzer (PSA) with the same input filter of the pacemaker was 1.7 +/- 0.8 mV (n = 93). In all cases, atrial sensitivity at implant was the default value +/- 0.15 mV. The atrial tracking capability of the pacing systems was assessed within the month and every 6 months after implantation by means of clinical evaluation, resting ECG, 24-hour Holter monitoring and the following tests: exercise stress testing, mental stress, isometric exercise, and nifedipine test. These tests evoke an increase of atrial rate in consequence of metabolic needs or as a reflex response. The criterion used to evaluate the correct operation of the system was the percentage of atrial synchronization. This was defined as the ratio between atrial triggered ventricular paced complexes and all ventricular paced complexes. All monitorings showed a ratio higher than or equal to 98% in a percentage of patients not lower than 95%. Mean follow-up was 385 days (range 183-1,370 days).(ABSTRACT TRUNCATED AT 250 WORDS)     

Dermoscopic Features of Difficult Melanoma

BACKGROUND: The dermoscopic diagnosis of cutaneous melanoma (CM) may be difficult because some CM lack specific dermoscopic features for melanoma diagnosis. OBJECTIVE: To evaluate whether a diagnosis of CM could be achieved using the classic dermoscopic melanoma-specific criteria, we conducted a retrospective multicenter study of 508 CM samples. METHODS: All the dermoscopic images were analyzed to identify the dermoscopic criteria found in dermoscopically difficult melanomas (DDM) and to examine the possible relation of dermoscopic diagnosis with respect to the difficulty of the dermoscopic diagnosis and the melanoma thickness. RESULTS: A significant percentage of melanomas, 89 of 508 (17.5%), were DDM. The criteria leading to a significant increased risk of DDM were presence of streaks [odds ratio (OR), 2.26; 95% confidence interval (CI), 1.15-4.47), absence or presence of regular pigmentation (OR, 3.41; 95% CI, 1.70-6.85), absence of a blue-whitish veil (OR, 4.04; 95% CI, 2.33-6.99), absence of regression structures (OR, 4.31; 95% CI, 2.42-7.66), and the presence of hypopigmentation (OR, 2.61; 95% CI, 1.49-4.58). CONCLUSION: A significant number of melanomas defy even dermoscopic diagnosis. Only a meticulous comparative and interactive process based on an assessment of all the individual's other nevi ("ugly ducking" sign) and a knowledge about recent changes can lead to the recognition of DDM.     

Spinal Cord Stimulation for the Treatment of Refractory Angina Pectoris: A Two-Year Follow-Up

Twenty-three patients affected by severe, refractory angina were submitted to permanent spinal cord stimulation (SCS) and then followed in our outpatient clinic for 24 months. During the follow-up period, the number of weekly angina episodes drastically dropped from 9.2 (preimplant) to 1.8 in the 3rd, 2.5 in the 6th, 4.5 in the 12th, and 4.2 in the 24th month, with a statistically significant difference (P < 0.01) between the first and last values. A significant increase in the average exercise time from 320 ± 120 seconds (in baseline condition) to 410 ± 115 seconds (during SCS) was observed at the treadmill stress test (P < 0.01). SCS was well tolerated by all the patients. However, 7 patients died during follow-up (3 myocardial infarctions, 2 noncardiac deaths, and 2 sudden deaths). Three generators were replaced because of battery depletion after 15, 17, and 21 months. No serious complication was observed. In conclusion, in patients with otherwise intractable angina or already submitted to myocardial revascularization, SCS is very effective in reducing the number of angina episodes. The time of the work during exercise stress test is also significantly prolonged.     

Quantitative Coronary Angiography in the Current Era: Principles and Applications

Coronary angiography, despite its inherent invasiveness and need for contrast media and radiographic exposure, is still routinely employed every year for the diagnostic and therapeutic management of millions of patients with or at risk for coronary artery disease. Whereas approximate visual estimation is the most common way to evaluate coronary angiography findings, since the late 1980s a number of investigators have developed and investigated methods of quantitative coronary angiography (QCA) analysis exploiting automated or semi‐automated edge detection. Despite the inherent drawback of QCA due to its focus on the contrast‐filled lumen of the vessel, QCA has offered and continues to offer important insights for clinical research and, in selected cases, clinical practice. This review aims thus to provide a comprehensive and updated viewpoint on the actual role of QCA.