Temporary epicardial left ventricular and biventricular pacing improves cardiac output after cardiopulmonary bypass.

BACKGROUND: To evaluate, with different pacing modes, acute changes in left ventricular systolic function, obtained by continuous cardiac output thermodilution in various subsets of patients undergoing cardiopulmonary bypass surgery. Increments of mean arterial pressure and cardiac output were considered the end point. METHODS: Fifty cases electively submitted to cardiac surgery were analyzed. Isolated valve surgery 62%, coronary revascularization 30% and 8% mixed disease. Left ventricular ejection fraction was preserved in 50%,36% had moderate depression,(EF 36%-50%) whereas 14% had severe depression (EF < 35%). Left bundle branch block occurred in 18%. Preoperatively 84% were in sinus rhythm and 16% in atrial fibrillation. The different subgroups were analyzed for comparisons. Right atrial-right ventricular and right atrial-left ventricular pacing were employed in sinus rhytm. Biventricular pacing was also used in atrial fibrillation. RESULTS: Right atrium-right ventricular pacing, decreased significantly mean arterial pressure and cardiac output (2.3%) in the overall population and in the subgroups studied. Right atrium-left ventricle, increased mean arterial pressure and cardiac output in 79% of patients and yielded cardiac output increments of 7.5% (0.40 l/m) in the low ejection fraction subgroup and 7.3% (0.43 l/m) in the left bundle branch block subset. In atrial fibrillation patients, left ventricular and biventricular pacing produced a significant increase in cardiac output 8.5% (0.39 l/min) and 11.6% (0.53 l/min) respectively. The dP/dt max increased significantly with both modes (p = 0.021,p = 0.028). CONCLUSION: Right atrial-right ventricular pacing generated adverse hemodynamic effects. Right atrium-left ventricular pacing produced significant CO improvement particularly in cases with depressed ventricular function and left bundle branch block. The greatest increments were observed with left ventricular or biventricular pacing in atrial fibrillation with depressed ejection fraction.

A simple technique to rule out occlusion of right coronary artery after aortic valve surgery.

Mechanical occlusion of the right coronary artery during aortic valve surgery is an infrequent but serious complication. Early recognition and expeditious management are important to reduce mortality. We developed a safe, quick, and easy technique to assess right coronary artery flow after aortic valve surgery. Direct intraoperative right coronary artery flow was measured by placing a transit-time flowmeter probe around the right coronary artery. We were able to promptly detect severe right coronary artery insufficiency in patients with acute unexpected right ventricular failure after aortic valve replacement.

Fracture of epicardial resynchronization lead caused by deceleration injury.

A 50-year-old man with heart failure, systolic dysfunction, and abnormal septal motion underwent ventricular resynchronization. Postoperative clinical and echocardiographic improvement was observed. Several months later, he complained of worsening functional class after a traffic accident. Pacing lead fracture was diagnosed. After replacing the lead, improvement of clinical condition and ventricular parameters was achieved. The role of seat belts in causing dysfunction of pacemakers and resynchronization devices after deceleration injury is discussed.

Biochemical markers of myocardial injury in the pericardial fluid of patients undergoing heart surgery.

The purpose of this study was to compare cardiac markers in the pericardial fluid and serum in order to evaluate preoperative myocardial injury. Thirty patients were divided into three groups. The first group (AVR; n=10) received an aortic valve replacement. The second group (SA; n=10) included patients with stable angina who underwent elective coronary artery bypass grafting (CABG). The third group (ACS; n=10) included patients with acute coronary syndrome who underwent urgent CABG. Pericardial fluid and venous samples were taken after opening the pericardium and 24 h postoperatively. Serum and pericardial concentration of troponin I (cTnI), creatine kinase (CK), its MB isoenzyme (CK-MB) and myoglobin were determined. Preoperative pericardial cTnI was significantly (P<0.01) higher than in serum in all groups. Preoperative pericardial CK, CK-MB and myoglobin were significantly (P<0.01) lower than in serum in groups AVR and SA. Preoperative pericardial and serum cTnI were significantly higher in the ACS than in AVR and SA groups (P<0.01). Postoperative pericardial concentration of all markers was significantly higher (P<0.01) than in serum in all groups. We conclude that preoperative pericardial accumulation of cTnI may reflect subclinical injury which may not be demonstrated by the usual laboratory tests.

Apical suction leads to severe ischemia of the ventricular apex.

OBJECTIVE: Apical suction devices allow displacement of the heart in off-pump coronary artery surgery. However, high vacuum pressure may injure the suctioned myocardium. It has been demonstrated that partial pressure of oxygen in the myocardium (ptiO(2)) is a sensitive and rapid indicator of myocardial ischemia. The purpose of this study is to evaluate the effect of apical suction on the ptiO(2) as an indirect measure of myocardial perfusion of the ventricular apex. METHODS: Twenty-six patients undergoing elective off-pump coronary surgery were studied. Intramyocardial ptiO(2) was continuously measured using a flexible catheter microprobe (Licox GMS mbH, Kiel, Germany). Patients were divided into two groups. In one group (Group A; n=14), the microprobe was intraoperatively inserted into the myocardium of the left ventricular apex. In the second group (Group B; n=12), the probe was inserted in the anterior wall of the left ventricle. Intramyocardial ptiO(2) monitoring was made with the heart in the resting position and after placing the apical suction device. RESULTS: In Group A, basal ptiO(2) was 15.3+/-7.4 mmHg. One minute after placing the apical suction device, the ptiO(2) significantly decreased to 2.3+/-1 mmHg (p<0.001). A progressive increase of ptiO(2) was observed immediately after the Xpose suction device was removed. ptiO(2) was 13.6+/-9.1 mmHg 5 min after releasing the suction cup and increased to 27.2+/-12.6 mmHg 20 min later. In Group B, basal ptiO(2) was 17+/-10.3 mmHg. No significant changes were observed in Group B after placing and removing the suction cup. CONCLUSIONS: Apical suction devices lead to severe ischemia of the suctioned myocardium. Collapse of coronary vessels due to vacuum pressure is a possible mechanism. Reperfusion occurs immediately after removing the suction cup and a significant reactive hyperemia is observed.

Respuesta: Implante epicárdico de sondas en la estimulación biventricular / No disponible

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Minimally invasive surgical implantation of left ventricular epicardial leads for ventricular resynchronization using video-assisted thoracoscopy.

BACKGROUND AND OBJECTIVES: Cardiac resynchronization via left ventricular or biventricular pacing is an option for selected patients with ventricular systolic dysfunction and widened QRS complex. Stimulation through a coronary vein is the technique of choice for left ventricular pacing, but this approach results in a failure rate of approximately 8%. We describe our initial experience with minimally invasive surgical implantation of left ventricular epicardial leads using video-assisted thoracoscopy. PATIENTS AND METHOD: A total of 14 patients with congestive heart failure, NYHA functional class 3.2 (0.6) and mean ejection fraction 22.9 (6.8)% were included in this study. Left bundle branch block, QRS complex >140 ms and abnormal septal motion were observed in all cases. Epicardial leads were implanted on the left ventricular free wall under general anesthesia using video-assisted thoracoscopic surgery. RESULTS: Lead implantation was successful in 13 patients. Conversion to a small thoracotomy was necessary in one patient. All patients were extubated in the operating room. None of the patients died during their hospital stay. Follow-up showed reversal of ventricular asynchrony and significant improvement in ejection fraction and functional class. CONCLUSIONS: Minimally invasive surgery for ventricular resynchronization using video-assisted thoracoscopy in selected patients is a safe procedure that makes it possible to choose the best site for lead implantation and provides adequate short- and medium-term stimulation.