[Left atrium rupture after non-penetrating injury to the back]. / Rottura di auricola sinistra dopo trauma non penetrante del dorso.

Survival after cardiac rupture associated with blunt thoracic trauma is very uncommon. In these patients successful management demands a high index of suspicion of cardiac injury. A case of a 24-year-old woman who presented unconscious and shocked in the emergency room after motorcycle trauma strictly limited to her back is reported. Rib and sternal fractures were absent; the typical signs of cardiac tamponade were not found. Therefore the suspicion of cardiac chamber rupture was not immediate and the cardiologist was consulted after several diagnostic exams. Transthoracic echocardiography showed a pericardial effusion with clots and initial cardiac tamponade. The patient was transferred to the operating room and a large hemopericardium was disclosed. Two lacerations were noticed: the first pericardial, near the inferior vena cava, and the second one in the posterior wall of the left atrium. It is possible that the associated pericardial tear and pericardial clots could have contributed to survival. After surgical repair, carried out during cardiopulmonary bypass, the recovery was quick and complete. This case report confirms the possibility of heart chamber rupture after blunt chest trauma even in the absence of obvious thoracic lesion and it shows that the presentation could be very insidious without a "classic" clinical picture of cardiac tamponade. In front of an unexplained shock after nonpenetrating thoracic trauma, a rupture of the heart chambers should be suspected and echocardiography is mandatory. In the emergency room environment pericardiocentesis should be performed only with a quickly available cardiac surgery or in the presence of overwhelming hemodynamic failure.

Time trends in the intracardiac potential recorded by pacemaker telemetry: comparison between steroid-eluting small area electrodes.

We assessed the time course of electrograms sensed both in the atrium and ventricle by two different steroid-eluting electrodes: Medtronic Capsure SP (with an area of 5.5 mm2) and Z (with an area of 1.2 mm2). We considered 68 unipolar electrodes: 31 atrial (19 Capsure SP 4523 and 12 Capsure Z 4533) and 37 ventricular (24 Capsure SP 4023 and 13 Capsure Z 4033) implanted in 47 consecutive patients (30 men and 17 women, with an age of 72 +/- 9.4 years). The pacemaker model was Medtronic Elite 7077-7086 (DDD-DDDR) in 25 patients and Medtronic Legend 8419-8424 (VVIR-AAIR) in 22 patients. The endocavitary signal (all patients had spontaneous rhythm) was telemetrically obtained by a Medtronic 9790 device and acquired on a personal computer at implantation and 7, 30, and 180 days thereafter. The signal was studied both in the time domain and in the frequency domain by spectral analysis. The following parameters were calculated: amplitude (A): peak-to-peak value of the complex; slew rate (SR) peak negative first derivative; F0: frequency at which the power spectrum reaches its maximum value; and bandwidth (Bw): expressed as the distance between the -3 dB points and statistically analyzed by a two-way analysis of variance with factors "time" (four measurements) and "electrode" (Capsure SP and Z) and repeated measurements on the former. Ventricular sensing: no time or electrode effect (P > 0.1 in all comparisons) was found for F0, Bw, or SR, while a time effect (P < 0.04) not dependent on the type of electrode was found for the amplitude of the signal. In particular, a significant increase was found between the measurement at 6 months and that at implantation (P < 0.004). Atrial sensing: A, F0, and bandwidth were not affected by time or electrode (P > 0.09), while SR behaved differently over time (P < 0.05) in the two electrodes (the Capsure Z showed an increase at sixth month [P < 0.04] compared to implantation). In conclusion, the Medtronic Capsure SP and Z electrodes proved to be valid and substantially equivalent as far as concerns the measurement of the intracardiac potential despite the difference between their surface areas. Further studies should be devised to assess whether transitory decreases of atrial Bw in the first month of follow-up observed in a few patients for both electrodes could be responsible for clinical episodes of sensing deficit.

[His bundle block 2:1 during paroxysmal supraventricular tachycardia involving an occult accessory atrio-His pathway]. / Blocco intrahisiano 2:1 protratto durante tachicardia parossistica sopraventricolare coinvolgente una via accessoria atrio-hisiana occulta.

A high degree AV block during paroxysmal supraventricular tachycardia is an uncommon and short-lasting finding in patients with intranodal re-entry circuits. The AV block is the result of temporary inadequacy of the infranodal conduction system--which is not part of the circuit--to cope with the sudden increase in heart rate in terms of refractory periods and conduction velocity. In a patient with paroxysmal reciprocating tachycardia at a very high rate (230-250 bpm), 2:1 intra-hisian AV block was constantly observed after arrhythmia initiation by atrial extrastimuli. This persisted for 1-4 minutes and then progressively subsided passing through a period of 3:2 intra- infra-hisian AV block until it reached 1:1 conduction with transient left bundle branch block. The latter occasionally disappeared as result of retrograde activation of the area of functional anterograde block and of subsequent noncompensatory pause, following a premature ventricular depolarization. Tachycardia-dependent AV block was abolished by verapamil and flecainide, because of lengthening of the tachycardia cycle length. Functional and electropharmacological features of retrograde conduction were consistent with an extranodal concealed atrio-hisian accessory pathway acting as the retrograde limb of the re-entry circuit. Moreover, His bundle electrogram was prolonged and polyphasic even in sinus rhythm. Therefore, tachycardia-dependent advanced AV block can occur not only in truly intranodal re-entry but also in very fast atrio-hisian re-entry tachycardias with evidence of transient impairment of intra-hisian conduction, distal to the insertion of the accessory pathway. Localized morphofunctional pathological changes in the His bundle are probably involved in the mechanism of this uncommon pattern.

Indenolol pharmacokinetics and pharmacodynamics after single and repeated daily doses.

The relationship between indenolol (an investigational agent) plasma levels and the drug's effect on blood pressure and heart rate was investigated after single and repeated once daily administration at two dosage levels (60 mg and 120 mg) in two different groups of patients with first or second stage hypertension, according to the World Health Organization classification. The pharmacokinetic data were indicative of a first order absorption-elimination curve; time of maximum plasma levels was 1.5 to two hours, and elimination half-life was four hours. The drug did not accumulate in the central compartment after repeated administrations. A long-lasting decrease of both resting and isometric exercise systolic pressure values was recorded after acute indenolol administration. Diastolic pressure was affected only by repeated administrations. The lower dose (60 mg daily) of indenolol did not affect heart rate, whereas the higher dose (120 mg daily) decreased this parameter. A steady state of pressure values and heart rate was reached after 14 days of once daily treatment.

Zidometacin: pharmacokinetic study on oral absorption.

Zidometacin is a new nonsteroidal antiinflammatory agent structurally related to indomethacin. Pharmacological studies show its favourable activity/ulcerogenicity ratio in comparison to indomethacin. Preliminary clinical data indicate a good analgesic effect after a single dose and an improvement of functional conditions of the joint after short-term therapy. Pharmacokinetic parameters and bioavailability of the drug were evaluated in the present study after the administration of a single oral dose. Nine healthy volunteers without impairment of hepatic and renal function were selected. According to a 3 X 3 replicated latin square they received a 100 mg capsule, a 200 mg capsule and a 100 mg solution (sodium salt). After various time intervals, blood samples and urines were collected. Plasma and urine levels were evaluated by means of a specific high-performance liquid chromatography method. No difference between plasma levels of capsules (100 mg) and solution (100 mg) was observed. Capsules showed a dose/level relationship between 100 mg and 200 mg. Mean half-lives (+/- s.d.) of capsules (100 and 200 mg) and solution were respectively 3.5 +/- 2.33, 2.8 +/- 1.22, 4.4 +/- 2.96 h. The 0-48 h recovery of total zidometacin (free + conjugated) was 27.4% (100 mg capsule), 20.7% (200 mg capsule) and 24.6% (solution). Only a small amount of zidometacin was excreted unchanged. The drug is well absorbed and its bioavailability appears satisfactory.